No, you mentioned it at the very end and my ears picked up on it. You just didn't have it on your comparison layout paper. It's the same steel I'm working in right now while I can get it. The 1080 series seems to be one of those blends that is only around here and there like D2, W1, and W2 were when I first started forging blades.
What I learned from this experiment is that even if you are a professional knife maker who does a month long experiment there will always be a 16 year old Redditor in the comments claiming to have a more informed opinion.
ALWAYS! And they just can't seem to help themselves. I even had a guy tell me I was "using the wrong steel to make a straight razor and razors need to be made out of stainless" (I make razors out of 1095, W1, and W2) granted they then admitted they didn't know what W2 even was... I seriously wanted to slap someone through a computer screen. Just had to remind myself, their just an idiot... idiots happen... its part of the human condition.
Basically, this is what I have always heard. HRC goes to edge retention. Proper heat treatment (temperature and tempering) goes to the toughness of the blade and how well it can take impacts and lessens the chance of breaking or failing during usage. To me heat treatment is all important. So a 57 HRC might be my choice over a 62 HRC I can sharpen a knife with a pocket diamond stone or ceramic rod even in the field. What I can't do is replace one in the field that breaks.
Exactly! His statement: "When people talk about performance they are talking about edge retention" really frustrates me because it's too true, when it shouldn't be. People these days obsess over edge retention and they get overly brittle and impossible to sharpen knives.
@@mikeries8549 When a knife is sold as being made with 'surgical steel' without being any more specific, that almost invariably means that it's made of 420J2 stainless (or nearest Chinese or Japanese equivalent). 420J2 is about as soft as a steel can be and still make a useful knife. It's sold as 'surgical' because it's extremely corrosion resistant, and therefore ideal for surgical instruments. it's more likely that this 'unsharpenable' knife is made of what would be considered a 'tool steel'.
Yeah, this has always been my understanding, since my interests lie more towards swords and other weapons as opposed to knives meant as tools. For a weapon, you'll often even prioritize durability over sharpness - a slightly dull sword is better than a broken one - so proper heat treatment is very important. It never occurred to me that for tool knives the priority might be reversed, but I guess that makes sense.
Most thorough, most underrated, most professional “knife and steel reviewer” knife guy on the internet for actual testing. You and Larrin Thomas are doing God’s work. Thank you. Been watching for years and I go back to watch any that I missed.
The answer to the quandary is obvious. The badly treated knives lacked handles and were therefore cold. Which meant they were shivering at the same frequency as an oscillating tool which caused them to appear artificially sharp
The trouble with heat treatment from a consumer perspective is that it’s hard to quantify. Someone can tell me that Spyderco (for example) does an excellent job with heat treatment, but someone like me doesn’t really know what that means. Hardness, on the other hand, can be tested with a fancy machine like yours and listed in the specs. I’m no metallurgist, but if I’m choosing between two knives I’m at least smart enough to know that 61 is higher than 58. Most people wouldn’t put the effort into understanding the intricacies of heat treatment even if companies presented it as plainly as possible. In other words, while heat treatment is likely just as important, hardness numbers still make more sense for layman knife shoppers.
Bzzzt. White iron can be 65 Rockwell, but would be a rubbish blade. Relying on hardness alone is misguided. It's like only relying on the miles per gallon when buying a vehicle.
@@OllieVK exactly. Some steel at 58 HRC will be far superior to another steel at 63HRC for example. Also two steels with the same hardness will be entirely different in performance, toughness, edge retention etc. What matters is the specific steel being used as well as the heat treatment.
Well, I've always heard one of the best in the industry is Buck, the whole Boss Heat Treat thing, but I sent a 110 in under warranty because the tip broke off on me. Of course, I'm hoping I had a lemon and I'll never worry about that again. A month later another Buck 722 Spitfire I had broke, the internal mechanism snapped or something sent it in, haven't gotten them back yet, but totally rethinking Buck.
As a metallurgist, if someone tells me that one is 58 and the other is 61 I would assume both could have come off the same load. We don't heat treat to a single hardness. We heat treat to a range. Even a hardness test block has +/-.5 HRc uncertainty.
So glad to see you back on RUclips. Thanks for doing all of this frustrating work for all of us. You really do a great job of simplifying tests and explaining it to your audience.
This is just based on my experience and own personal research but likely the reason why all three of the knives had similar edge retention is because in reality what you're testing is abrasion resistance which with a more basic carbon steel like the 1084 that you were testing with, it pretty much just comes down to the hardness (and edge geometry, which was identical) of it which all of them were nearly identical. Toughness, strength, and apex/edge stability are much more open to variation depending on the other specifics that come along with heat treatment, which is exactly what your testing showed. Honestly, these results didn't surprise me at all, the results reconfirmed prior conclusions I've made. That's why HRC is just one indicator for a good heat treatment and isn't the only way that a person should be evaluating purchasing a knife. Videos of real world testing actually demonstrating the edge retention, toughness, strength, and edge stability are the best resource.
Yeppers. 1084 is a pretty simple steel. Going to A2 yields much greater abrasion resistance (edge holding) because of the wear-resistant complex carbides formed, but heat treating is a little trickier - you need to watch your austintizing temperature and temper to Rc58 to get a maximally tough blade. If you're going to put all of that work into a blade, use a good steel and have it properly heat treated.
I tend to buy knives with higher claimed HRC. The chipping issue is something the OEM's tend to discount as ____________ steel is difficult to work with and prone to chipping. Maxamet knives are a good example. I purchased two identical knives, one chipped like mad, the other ZERO issues. I sent the chipping knife back to the OEM and was told the Rockwell was "within spec" good luck with the knife... The chipping issue eventually sharpened out. The knife still has damage where the chips were too deep to completely remove. (waste of knife steel, only cosmetic issue.) Thanks for the video, excellent work! : )
Man, you seriously know science, especially after including the exceptions and disclaimers. I love your approach on steels and their properties, and your channel of course.
Dude you rock. So many people treat (no pun intended) this topic as yes/no when there are lots of maybes involved. To say nothing of whether the knives get used hard enough to discern a difference. Bravo
Thanks for an excellent video. An interesting test would be to take the knife with the poor heat treatment and re-treat that knife with the good heat treatment to see what effect you would get. The long and hot initial treatment would cause grain growth, but the quench might set up the microstructure to have a better grain size on a second heat treatment. The other possibility is that the prior austenite grain boundaries are already established as large grains and that you wouldn't fully recover the grain structure. Getting the steel back to where it should be might require annealing, rolling, and heat treating from the beginning. All of my classes in this area were too long ago for me to remember what the answer is.
You did a good job! Hardness determines edge retention and abrasion resistance. But grain size determines toughness, in choppers, axes, and swords heat treatment is key to the performance of the blade. I have had poorly heat treated blades snap, much sooner than a properly heat treated blade.
Another point is that you can get a thinner edge (more acute angle) with a tougher steel, without getting chipping. A thinner edge INCREASES edge retention. So the truly telling test would be to grind the 3 knives to an angle where they don't chip or roll on normal cutting tasks. Then see how the edge retention compares. (follow up video? *wink wink *)
You are 100% right . The problem with in the knife community is there is alot of people with only 25 to 30 % of the knowledge needed to have a opinion that is relevant. that being what they read on a data sheet that show what a steels maximum hrc is but they don't understand that data isn't realistic as even if you do a heat treat perfectly it doesn't mean that you are going to reach that hardness or that max hardness doesnt translate to optimal performance. And they don't understand that as a knife maker we are trying to not necessarily to reach optimal hardness but optimal balance for the steel we are using and for what the knife is going to be used for . And these same people if the steel wasn't marked they wouldn't know the difference between say s30v and 1095 . Same goes for alot of knife reviewer who drive buying preferences in the edc and knife communities.
I do think that for the vast majority of knives, hardness is still a top priority. But, for the vast majority of knife consumers, there still needs to be a toughness balance. Since knives are often abused, dropped, thrown around, etc. A full flat ground 1084 steel blade at 63rc and 0.010 behind the edge would make a great cutting blade but don't drop it or open a paint can. Most knife buyers aren't knife people and expect one knife to do everything. 🙂
@@OUTDOORS55 very . True what I'm seeing is people that watch a bunch knife reviewer content and then want to question why I'm not using 20cv or the like and how come I'm not shooting for 63-65 hrc . And then spend a hour trying to explain to them that yeah it's great steel but not in every application and that I'm trying to strike a balance of maximum toughness with still maintaining decent edge retention because sharpening is always cheaper and easier than a blade that breaks if you drop it or a tip comes off trying to remove a staple .
This was amazing. It confirmed a few suspicions I had too. Thank you so much for going through all this effort. It would've taken me years to get this amount of experience.
Hey there, great video! I wanted to add a little thought to the discussion that you didnt mention in your video. I believe it is wrong to reduce the knives performance to edge retention of the blade where harder means better. By following through with that thought, the best knive would be a knive that has not been annealed at all. Your findings do prove that there is a difference in quality that is independent of the hardness value, after all nonne wants a kitchen knife to break upon cutting into a bone. Wich could happen with a knife that is equally bad as the third one. But on the other hand i do not believe that it is possible or sensible to try and find a metric to measure the quality of the heat treatment, since the manufacturers of quality knives have figuered it out anyways and the manufacturers of bad knives (i.e. the 26$ damacus knive you teste) lie about their products anyways. I believe the current system, where we get an information about the hardness and assume that it has been heat treated correctly, is flawed but there is no realistic benefit for the average consumer to change anything about it. Btw i love that you try to test things, that are currently measured by feelings and subjective means, in a way that is as scientific as humanly possible. Keep up the good work man!
Unfortunately the relationship between toughness and hardness is not linear and quite steel specific. The poorly treated knife at 58 could be notably less tough than one at 61 with a good treatment.
@@oldeays5085 depends on how it got there. Pull out of the fire/oven and quench and you can get to 58 without even tempering if you mismatch the steel and the quench.
Great testing and discussion!! I fully agree, that’s why I don’t get excited about overly hard steels, unless they are also tough… pure edge retention only matters if you slice cardboard or rope all day in a controlled manner, but if you start using a knife in a realistic way, who needs a fragile blade that will be difficult to resharpen and strop? Favourite tool steels would be m4, k390, favourite stainless would be cpms30v… looking forward to trying out cruwear and magnacut, don’t care about 15v, s90v, m390 unless it’s heat treated to perfection, also don’t care about 110v or maxamet
Great video and great explanation. Thank you and congratulations. The main problem here is that, when you buy a knife, you will never know if the heat treatment was made well, good or bad... Only if you abuse your knife to the breaking point.
Very interesting results. Not entirely what I expected. Thanks for all that hard work! I'm sure it was a pain in the drain, but we're all more knowledgeable for it.
Interesting results, toughness definitely matters for chipping on the edge. I imagine the results for edge stability in super steels would be interesting.
Interesting demonstration, definitely food for thought. A lot of trust goes into the purchase of a knife. I'm very careful with my good (expensive) knives because I don't want to mess up the finish, even knowing the knife is suppose to be very tough. How a knife cuts and how often it must be sharpen is about the only way a consumer can get a sense of whether the knife is satisfactory. I suppose if a knife manufacturer did a poor job with their heat treatments it would eventually get out thanks to social media. They have to do a good job to protect their reputation id they want to stay in business long term.
I'm just learning about all of this, your work and demonstration made it clear and easy to understand. Encouragement and props on what you did and shared. Outstanding job!!!
Really well done video! It shouldn’t be much of a surprise that these all had the same edge retention. Regardless of crystal structure, HRC directly correlates to abrasion resistance, that’s effectively what it measures. Harder things will resist abrasion better than softer things. The grain size, which is the only variable here shouldn’t effect how the steel wears in a pure cutting application. Hacking through some boards would likely show more micro chipping and therefore faster wear on the poorly treated ones though.
For tool steels (slightly hypereutectoid alloy steel) 3rd critical point is somewhere arround 860 degrees centigrade. For quenching you want to bring it above critical point 1 where it starts austenitizing (around 790 degrees centigrade) but under 3rd critical point where grains start to overgrow from heat. Depending on the temperature you have to soak it for a different amount of time to fully austenitize - lower temps require longer soak, at higher temps grains recrystalize faster and actually can overgrow also if soaked too long despite being within ac1 to ac3 range. For 800C 10-20 minutes is very correct. 870C might be above ac3 already, so it's rather a no go zone, but you might get away if you just bring the piece to that temperature and quench without any soaking. 980C for 40min - I'm more than very supprised the blade didn't shatter into million pieces at quench. You can see after breaking how swollen the grains are from overheating. The moral of this experiment is for a given steel, hardness comes from crystalline structure while toughness comes from crystal grains size?
This was a great, down to the bones kind of video. I found it especially helpful since I'm currently using only 1084 and really trying to pin down how to get my best results with it. When I worked 1095 years ago out of an anthracite coal forge, all my blades failed because of grain growth. I just couldn't give it a steady soak without going too hot at some point and the grain looked like that moldable sand kids play with. Total disaster for me. I'm trying to focus now on maximizing durability. I'm getting ready to make a knife for my little nephew for when he goes out fishing or hunting with his dad, and if he's anything like I was as a boy, he'll need a blade that can hold up to um,...'rough' treatment 😉👍
if you're heat treating in a forge, you'll need to heat the steel and not the forge. The advice to try to make a forge perform like a furnace is bad advice for simple stuff. If you can have a hot spot at your burner or burners and the ability to move the blade in and out of it, you'll get no grain growth with 1084 and 1095 if you do a low temperature pre-quench, then do thermal cycles - pull the blade out of the forge and let it cool to black each time and then heat only to nonmagnet plus a little bit of a temperature overshot as much as you can get one in literally 10 seconds and then quench. You should end up with finer grain than you'll see pictures of anywhere else and nothing unusual in the structure of the steel. if you use 1084 and overshoot temp once after the thermal cycles "just to be sure it's hot enough" for 15 seconds, the grain growth will double in size. 1095 is a little more forgiving, but it doesn't have any real margin to give in toughness. You can practice the thermal cycles by overshooting temperature on a sample for 15 seconds and examining it vs. something annealed once and quenched just after nonmagnetic. The latter will double in size grain wise. Take magnified pictures of the grain, then do thermal cycles with the large grain sample and bring it back to grain smaller than the part that you intentionally didn't overheat. That gives you a very good idea of what you're seeing in forge by looks and by time and how much it affects grain. You'll want to take an offcut and do this with everything you'd like to use. 80crV2, for example, suffers no visual change after a 15 second high temperature overshot. That doesn't mean the intentional overshot past just a little is a good idea, it just lets you know what you're dealing with.
If you want even heat in a solid fuel forge, place a thick walled (thin walled works too) pipe in the coals and bring it to temperature, then place the blade inside and the radiant heat will heat it up very evenly.
Watch larrin's video on heat treating with a forge. Just only to magnetic from a normalized blade. If it's not magnetic it's hot enough, no matter the temperature, if starting from normalized steel. You don't get a huge range of hardness value this way, though, so you have to choose the steel for the task. 52100 will be hard as hell but not tough enough for a sword where 5160 would be a better choice.
Very educational. Most folks would focus on the hardness and not consider toughness. For knives that are used in the great outdoors and need to be dependable, toughness matters. Thanks for taking all the time to do this, and for sacrificing your arm hairs in pursuit of knowledge.
These results make perfect sense. Wear resistants as far as I know is a quality of the steel, and the hardness. Toughness is greatly enhanced by reducing retained austentite and when a steel is soaked at a higher temp longer it can increase that pesky brittle stuff. At the same hardness and wear resistance the knives should all slice the same. If your chopping however I bet chips would show up fast in the poor heat treat. Also I bet the crappy heat treats lead to less ability to flex when in a bending test. Great job showing how toughness and edge retention are manipulatable factors and how we can improve our outcomes
I've been watching your channel since the start and just wanted to tell you how much better your knives have gotten with all the experience you've gained. Just wanted to pass that along. I really enjoy your videos, keep it up my young friend.
My understanding is it's a matter of finding the balance between hardness and toughness. For annealed O1 Tool Steel which comes at RC 45 (how you normally buy it from a supplier) that amateur wood workers use for making chisel blades, plane irons, etc., one is supposed to first shape the blade while leaving the cutting edge about a 1/64" thick to ensure carbon retention, then heat the final ½" to ¾" or so of the working edge to 1,500º F then immediately plunge it quickly and completely into a container of enough oil (motor oil smokes, vegetable oil does not) so it doesn't catch fire, which gives it a hardness on the Rockwell scale of about +-75. Then it should be put in a 350º to 400º oven for 30 minutes to an hour to be annealed to an RC 60/62-58/60 respectively. Too hard is brittle, meaning it shatters when stressed; too soft and it won't hold an edge. The trick is in finding the balance between too soft and hard enough to take and hold an edge w/o shattering.
There is always a balance. O1 is a deep hardening steel, meaning it has a slow cooling curve for martensite formation to occur. Im not sure o1 is a great steel for home heat treatment unless you have a temperature controlled kiln, due to the carbon needing more time to dissolve at austenitizing temperature. 1084 would give more consistent results if using a forge. Thanks for the comment 👍
Interesting video! Perhaps they all performed the same in the edge retention test because your tests were focused on abrasion resistance type tests, or is that correct? Since there are several modes of sharpness loss that may be experienced during varied practical use, such as micro chipping, or deformation... 1084 being (basically) a eutectoid steel the austenitizing temp has no real bearing on carbide content in finished product, or potential retained austenite like it does in higher carbon steels, both of which would make a big difference in the abrasion resistance aspect of edge retention. In other words, if you tried this with a higher carbon steel you might see some additional significant differences between the samples. I like your point that RC hardness isn't really the best reference point for blade performance!
And this is why we have destruction testers for "hard use" outdoor knives. The big issue is how easily they break. People sometimes laugh at the destruction testers, but they bring an important service to us. For example, a good heat treat will yield a knife that cuts well and can also take body weight "step" loading. A TOPS knife may have a slightly low HRC and need sharpening more often, but is unlikely to break in the field. The extra insurance comes at a cost. We're usually wishing for the best compromise rather than the safest knife, such as you get from a careful heat treat and a good hardness. A bad heat treat such as on the many botched Asian Schrade outdoor knives may break in half from just a bad landing when throwing the knife into a tree. So it should come as no surprise that most throwing knives rarely get up to 55 HRC. A sushi/sashimi knife may be made pretty hard, with a very shallow angle, but it will not see any rough use by a competent sushi chef. It would fail these tests, but no one would notice or care. If the angle was extremely thin, then these toughness issues would become more important.
You're killing it boi ! ! ! Absolutely fantastic content . The way you test stuff in a kinda scientific real world use way is great . I don't know how else you could test knives any better . Sure all super scientific in a lab etc . But who uses knives like that? Or totally real world with no empirical data gathered whatsoever . Just gut feelings and personal anecdotal impressions . Keep it up . Those close ups are stellar BTW ! P.S. How's the house renovations coming along ? Fattrucker
Great vid really enjoying the content. I think HRC is a good indicator of what heat treaters are looking for when they know the process was done correctly. If your expecting say 61 HRC but you only get 55 you know something went wrong with the process or the problem could be the steel itself. For consumers when buying from a company they are hoping the HRC is a result from a good heat treat process as an indicator of steel performance during cutting. For the typical person who isn't into the depth of heat treat process it's another statistic that they can slap on a label and say "we did the steel correctly" and the consumer will go for it because a higher number is better right. Just my opinion though. Thanks for the great vid and keep making sharp things fun and enjoyable.
5:57 Dude. I'm looking at those images and my mind is blown. Like, you can see the scratch marks from the grinding. But look in between the scratch marks, towards the edge. That is really smooth. Wow! For some reason I was expecting scratch marks all the way down. So unexpected.
Well done. I think what you are highlighting the difference between edge retention and toughness in a very understandable way. High performance is really a combination of both.
Great video... so happy I came across it! I am not sure about HRC being equated to a "good heat treat" but I think HRC is meant to be indicative as to the other attributes of the steel. Depending on the heat treat (to my understanding) will help dictate the trade offs between stainlessness/corrosion resistance, toughness, and edge retention. Today, this has become a huge talking point I believe because it attempts to help people compare apples to apples. If I have two knife manufacturers and the same steel if the HRC is at least measurably the same... you have 1 point of true consistency for comparison not good or bad..... just something consistent to view the rest against. But as often said as of late.... geometry is more important than anything else pretty much... but without heat treat do you even have a knife?
Okay, we seem to have established that hardness determines edge retention. However, you also demonstrate that keeping that edge from breaking depends on quality of heat treatment. Great test.
Edge retention without much side load is really just testing the steel and its hardness - slowly wearing the edge down to dull-ish. There would be very little rolling or chipping unless the steel is extremely weak. So you are testing the hardness, especially when they are the same steel alloy. You got that steel to 60-61 HRC on each knife, so short of extremely weak steel (e.g. walmart knife) they should perform in slow wear mode just about the same.
EDIT: You have gone above and beyond regarding the scientific method in this video. Hot damn, sir. Holy moly, from the first 20 seconds of this video I knew I'd like you as a craftsman if we met in person. I like to faff about and shave with a straight razor from time to time. Those are the only blades for which hardness is a primary concern for me because they're exposed to no strain. For my utility knives I like it if they keep an edge well, but they need to be able to do it while I'm striking them with an olive wood bastoni or clipping a bone in an animal I'm preparing to eat.
Personal experience, using a knife to pry or use the back for slot screws. Brittle blades break or chip. Flexible blades twist and bend. Sharpening and edge retention. Harder steels don't always retain their sharpness as you would expect but always seem more difficult to sharpen. Flexible steels seem to hold and retain their edge. Are more forgiving of abuse. That it is ill advised to use a knife to open cans, always use a screw driver. Preferably a slot head heavy duty. Never electrical screw drivers.
So how we sharpen knives is important. I have a Spear (AlexDrow) I would like to put an edge on. After some research it is 420 Stainless a common material for surgical instruments and kitchen knives as well. I have a dremel or I can use a knife sharpening wet stone (more forgiving and lower temperature.) Now if I use the Dremel tool and heat up the edge too much during the adding an edge process I will change the properties of the material. Then it may not hold an edge as long if I change the crystalline structure due to heat. It can also be more prone to rust in the area heated.
It would be interesting to see how they perform in processing a deer. From skinning, to parting and even boning. At least that is how I judge my knives. Hold a reasonable edge and not break. Keep up the good work.
Toughness and hardness are often displayed as opposite ends of a sliding scale. Hardness is a major factor in edge retention. Toughness is closely related to brittleness. A decent knife maker (both mass produced and artisan) carefully balances toughness and hardness while designing a final product. It is easy for the advertising departments to just push hardness as edge retention. That way consumers won't get confused by important information that might complicate a choice. Give one hardness number and say "hardness = good" and the masses will proudly nod in agreement. That's why pocket knives commonly range from $5 to $500. They are selling to crowds who want to be told they have the best, while not wanting to be confused by inconvenient information. It takes a "knife person" to care about the difference.
Having broken a few tips, I now grind my 'utility knife' edges to a point with a more robust angle. Still sharp where needed, but significantly less chance of nipping the tip off. The last 10% of the edge angle is increased by 30-50%. e.g. 22deg progresses to between 29 to 33deg.
I use 1084 vs 1095 because I have found out that the 1084 seems to be more forgiving in heat treatment vs 1095. The 1095 can get a bit more brittle if an error occurs, while the 1084 seems to withstand a bit better. I kind of wonder if it is due to the carbon content. Higher carbon= shorter crystalization making a harder blade, and during the tempering stage if you start with smaller crystals you reduce the ability to grow a proper lattice in the metal is you have gone outside the perimeters of the steel. Where as the 1084 has a slightly less carbon content which allows for longer crystal formation making it a little more forgiving in the tempering process. Hell, there are a multitude of arguments that can be made in this discussion, but my choice is a nice 6" blade full tang 1084 knife that I feel comfortable using and have less concerns when having a home blacksmith producing a blade I like.
I think this proved more than anything that1084 is as close to a dummy proof steel as there is! I appreciate how far you took the testing. I don't think you could have done anything different to make it better. With a different steel like 1095 it would have been much different.
I was one of the people complaining early on about the Rockwell testing -- because I just don't think it tells you very much about how a knife is going to perform. It's obviously a multivariate issue with hardness, heat treat, steel and grind interacting in complex ways. These days, I focus primarily on design and ergonomics and don't worry at all about the steel or edge retention. I prefer carbon steels that are easy to sharpen. Blade gets dull, I resharpen.
it would be interesting to see how the un-tempered knife at 65 hardness compared to the other three, in the same test categories. A fair assumption would be that edge retention was better than the others, due to the greater hardness, but toughness would be rubbish
Good video. As a maker, I get enraged by the use of the term "edge retention" testing when the test you are performing (slicing stuff like cardboard) is NOT EDGE RETENTION TESTING!!! For crying out loud. It is called "wear resistance". NOT "edge retention". Actual edge retention is the sum of all of the properties, toughness, hardness, wear resistance, apex stability, corrosion resistance (to some extent). And that is why you are getting similar results with all 3 knives in "wear resistance" testing. Those other factors, like toughness, apex stability, etc aren't going to have a noticeable affect when slicing stuff. Grain size plays very little role when slicing into stuff like cardboard, but grain size has a massive role in stuff like tip strength and apex stability.
My conclusions from this are that heat treatment details are more important to blade toughness than edge retention. HRC seems to single handedly determine edge retention (within the same type of steel). I'd definitely rather own knife 1 because it will last much longer.
The reason you got the results you got is that geometry is king when it comes to knife performance. Cliff Stamp cut a lot of cardboard with a mild steel tension bar he ground down and put a coarse edge on. There is a RUclips video or forum post about it somewhere.
Love your setup, _especially_ because you're doing "pro science in a garage"... The close-ups keep teaching us a bunch of interesting things. Given you were aiming for the same hrc and found the same "performance" on all 3, would you say the performance is most linked to the hrc, or to the steel type? (i.e. if it's the hrc, similar results from other steels at the exact same hrc would be expected; if it's the steel type, then similar results would appear at (slightly) different hrc in the same steel, and different results in different steel at the same hrc)
I'm a retired tool maker, and machinist, and have many factory made knives. All of them start out holding an edge, but the more the edge gets removed through sharpening, the softer the edge gets, to a point were they cut 2 or 3 times, then need resharpening. I've made knives from 01 tool steel, hardened and tempered to 65 rc, and can skin 3 or 4 moose, without needing to sharpen. I certainly would not cut nails with my moose knife, but I'll guarantee it will shave you after you've finished with the moose. If you expect a knife to shave you, AND cut framing nails in half, I recommend using an axe. I don't use screw drivers as prybars, and don't use wood chisels to scrape off paint. I also carry my camp knife that I eat with, cut kindling, rope, and moose tendons. The right tool for the job. In 40 years, I've skinned dozens of moose, deer, and bears, and my skinning knife gets the once over on a 1,000 and 1,200 diamond lap, at the beginning of hunting season, and it's good to go. I heat blue the spine of the blade back to 45-50 rc for ferro-rod striking. My moose skinner has a 3" rad. hollow grind, with 10 degree point,, wide radiused tip ending at 70 degrees to the centerline, micarta grips, and stainless guard, and butt plate. The leather sheath is dipped in melted wax, because 01 tool steel will rust. My camp knife and machete have straight grinds and the leather waxed sheaths, for the same reason. There will be people that disagree with me, but unless you've spent more time on a Rockwell hardness tester, heating and quenching every tool, and die steel available, I'll keep my knives the way they are. I have yet to see a better blade from any manufacturer, than mine. PS, my machete is made from an old, 1940s tree saw blade from a paper mill. I think it is 1/4" thick 4340 high carbon steel, from an 8 ft dia. blade. It cuts nails, and trees.
These results make a lot of sense. The number one factor of cutting performance is blade geometry, with these knives having identical geometry it make sense that they would perform the way they did. I’m not sure you would see cutting performance differences even in catra testing.
Untill further and extensive research, the results apply only to this one batch of steel. Knife performance is more that just edge retention as it is affected by size/weight/shape of the blade/handle, edge geometry, intended usage/purpose, and other factors. Steel performance is also more than edge retention, it includes hardness, toughness, corrosion resistance, and again other factors. Edge retention seems to be mostly related to hardness only regardless of everything else. Great great test! Good job!
I agree I think posting hardness values with the knife is important but also actual tested hardness values not what you were aiming from from data sheet. I don’t care that your target was 60 hrc what did you actually get. Hardness values let’s be determine what I can expect from the knife vs another knife in the same steel. If my option was 61 hrc and in a similar knife with the same steel the maker ran it at 58 I would go with the 61 hrc knife. Running knives softer usually tells me the edges are thicker and the maker might be trying to save time and money by running it soft so it’s easier to grind and finish. I just finished a large 4V camp knife that’s sitting at 63 hrc and I’ve had no edge issues in all of my testing with it.
Im wondering if there wasnt much of a difference in the sharpness testing because 1084 is such a simple steel that it doesnt have that much edge retention anyways. (I love 1084 fwiw) Hard to say. But this test was VERY well done, i am hugely impressed by the amount of effort you put into this. Bravo sir.
Finnish Marttiini knives are heat treated to hardness of 55-58 usually max 60hrc. They have used this same steel for a very long time. It seems that Marttini is saying by doing so, that its just more practical to make them tougher and not change the steel but to make sure they get all out of it with a correct and well controlled heat treatment system? Marttini puukkos can withstand - 25 Celsius degrees of cold and you can still baton wood with them without any risk of breaking the the blade. Its just basic 14% chromium stainless steel and its foolproof even in extreme cold conditions and field sharpenable. They have the much needed heat treatment experience with this steel to get it right with this steel everytime. It seems that getting the heat treatment right in the factory almoast all of the time is more important than people think. If the steel is lets say a supersteel like Magnacut but it would be difficult to heat treat right most of the time it requires more precition to get to job done and usually it then cost more. So is it fair to say that it is more practical to use steels that are hard to heattreat badly? I dont know exactly what was the problem with the DBK magnacut steel in the Bark River knife company knife they used but I remember that it had something to do with the heat treatment. Its not a surprise that in the beginning the companys dont get it right so well, but I wonder that are there too many knife steels that it would be possible to knife making companys master all of then at the same time? Less is more sometimes?
Seems like this makes sense. Hardness is more how it's holding it's shape, but doesn't factor in the "structure" of the molecules/grains (which heat treating properly helps address), so you're able to retain the shape in things that don't strain the internal structure as much...but once you start doing things that rely more in the internal structure, it starts falling apart. I'm imagining it to being like building a house with proper angles/load bearing/structural considerations vs one that doesn't...it'll get the job done just fine until something tests the structure, and it'll collapse or various parts of the frame that was under odd stress will pop out.
I know this pisses people off in the 1095 fanboy club, but 1095 isn't super tough. Most companies under harden and over temper that steel and would probably have MORE toughness with simlair edge holding in a lower carbon steel like in the .60-.80 range 5160, 8670, 15n70, 1060, 1070, 1075, 1077, 1080, 1084, 80crv2. You won't see a good sword or axes in 1095 for a reason. The extra carbon makes the steel less malleable and flexible. Even with the extra tempering compared to a lower carbon steel at similar hardness. People really like 1095 though, and those companies can do a mass production in house heat treatment and the wear on tooling and abrasive cost is lower then even if they changed to 52100 at the volume they produce at. It sells, people like it, people know it, why change l guess. There are also more alloyed, low carbon steels that can make some of the most durable almost unbreakable knives and tools like A8MOD, INFI and 1V to name a few.
One thing which is repeated by many sources is sharpness depends on: edge angle, steel, proper heat treatment. Instead of what I’ve seen on this video I would preferred to see measurement of apex width (hopefully giving some sense of sharpness) and Edge-on-up-tester numbers for blades. To be honest pictures of edge were not obvious self explanatory as said (and forgive my ignorance if I say something which makes no sense. Not an expert). For me knife 1 looked as it had compacted instead of rolled apex (perhaps optical illusion and/or lack of understanding, anyway that is why I mention measurement of width of apex), while 2 and 3 slightly rolled. For me also, edge retention is important but definitely not the most important parameter. The most important is simply sharpness. Only then, once knife is sharp, the question comes how well it can hold this sharpness. If it say it will hold it well for very long time, than well, let maybe make it sharper and see how long than it will hold. If it looses sharpness immediately, well then let’s make it maybe less sharp and see can it hold sharpness in some time which makes it practical and feasible to use (where exact number of this time will very on person, knife, use and need of course). Point I try to make, providing edge retention information, without providing sharpness information is meaningless. So what if some edge will keep its retention if it was perhaps dull (or duller than it could be) in the first place, or width of apex of all three knives possibly identical, just disfigured differently (no wonder all three would have than same edge retention- right?). What it says about holding edge would it be made sharper? Would it still be the same or different? Let say edge 2μm (or whatever) wide with average sharpness of 78g on edge tester holds 30 cuts on rolled towel, after which it decreases to such and such values (or even better, how much it exactly decreases after each cut). Sharper the better as long however as sharpness is retained in reasonable time. What a point of comparing three different heat treatment if each reached same HRC? Is it not a point of “proper heat treatment” to reach higher HRC (within reasonably decreased thoughness and brittleness), so edge can be made to more acute angle it will be able to hold? Again, please forgive me if I have some misconceptions, misunderstanding or other lacks. Not pretending to be an expert. Really relaying information (or misinformation) I absorbed (well or not so well) from watching probably well over 100 RUclips videos now, plus various forums. Question which bug my mind is: how to identify proper heat treatment in knife which is to be purchased? How exactly (numbers) Kasumitogi or Honyaki affects parameters of knives. ONLY measured values provide sound information. What “better” say edge retention really means? 10, 50, 250% better? Better for acutely sharpen, average or dull edge? If acute, how acute? And so forth…
Somewhat surprised how they all dulled at the same time regurdless of the heat treat. Excellent job on keeping all of the other factors so even for each knife as the tests progressed. Think I have a better understanding of some of the aspects of heat treat and how the edges react to those tests.
Very practical testing. Every time I watch your videos, I can't help but chuckle at your quote "...Is this even wood..." Thanks for helping me as I'm lying in my recliner at home after having "unexpected" open heart surgery. Maybe by the time things cool down here in NC, I can start swanging my hammer again.👍
If you still have some kind of uncertainty or doubts, I'd suggest seeing if you can do a collab with Project Farm on testing the different blades. He's pretty through and open about his evaluation process and documenting it for everyone to see. Maybe his approach could answer some questions, in either confirming things or making any differences more apparent. Maybe make it a blind study on his end, so all he knows is getting blades A, B, and C - and then do a reveal after the results come in.
Absolutely good stuff. It would probably be the best if the knife manufacturer stated steel and hardening and tempering protocols. As well as the hardness. Would give a better if not absolute gauge of the temper of the blade. Probably the most important part of the knife is the heat treatment. Everything else can be corrected with abrasives and effort. Thanks for your time and knowledge!!!
after being in the "discussion" in the other video and seeing all the work in this one I had to drop a comment for the algorithm at least. great content and video presentation as usual, top notch. was interesting to see real world example and comparison with very low carbide forming steel.
I dunno, maybe it's because my interests lie more towards swords and daggers rather than knives, but this all seems to make sense to me. Blades of equal hardness have comparable sharpness and edge retention, but a good heat treatment makes the blade over-all stronger and more resilient. This is important for edged weapons that need to hold up well to impacts and mechanical stress, and often durability is prioritized over sharpness rather than the other way around, which seems to be the case for tool knives.
The broken knife is Martensitic with the classic tetragonal crystalline structure. The RC point of when it changes is real close to 60. Once your over 1500 degrees it starts to decarbonize making it brittle.
When I clicked on this, I was expecting something to surprise me. The only surprise was that it turned out exactly how I thought it would. The problem amongst the community these days is that HRC is seen as THE go-to metric for all things "quality". That is not to say that it shouldn't be looked at, but it is somehow the soul focus for most people. Also, there are many people who buy sprints of the same knife in different steels and consider only one or two aspects of testing and start proclaiming their findings as definitive results. Social media absolutely helps perpetuate the falsity as well. In reality, most people couldn't take the Pepsi challenge with identical blades and tell the difference between high carbon steels and super steels. They simply do not use and test them extensively enough. It is the equivalent of taking one shot from a firearm, getting a lucky shot in the 10 ring and calling it accurate. The ideA that we live in a time where the availability of so many different steels that perform extremely well is like living in a dream world. Imagine time traveling to pioneer times where something like 1080 was the predominant steel and showing our ancestors a knife like they use in well done 3v... It would seem like witch craft! At the end of the day, it is a deep rabbit hole and it is always fluid in its complexity. The best we can do is try to consider the basics of what is known and keep testing. That may seem like the goal posts are always going to be moving, but along the journey you find your favorite.
Hardness isn't everything as can be seen in your tests or on say Spyderco VG10 at about 60hrc and Japanese chefs knives or Mcusta folders in VG10 at about 60hrc as well but have up to twice as much wear resistance. But then we see knives from Cultrotech in m390 do 2-3 times better(depending on "regular" vs custom heat treatment and hardness) than Spyderco or Benchmade. A big part is because Denis Frolov/yanhook is a master at heat treatment but that better heat treatment also results in higher hardness, 63.5 hrc for the "regular" and about 64.5hrc for the custom heat treatment. Those knives don't just perform better because they're harder. They have a better heat treatment protocol which results in harder blades. Hardness isn't the end all be all but it can give you a hint on performance. M390 at 58hrc isn't going to perform that well because to have it that low there's some off with your heat treatment. Either no cryo, too low of a soaking temperature, too long of a soak, poor quench, too high of a temper temperature, too much retained austenite as a result and you get a steel that performs worse than it should. Great video. Thank you for taking all this time and effort to make an interesting and educational video.
@@OUTDOORS55 true. Though I think it's those steels(m390 class especially)that a lot of people just concentrate on the hardness number and nothing else. It was really surprising to see that the wear resistance was the same while you could clearly see the difference in toughness and edge stability. Just shows to show that steels can behave really weird sometimes and not at all to our expectations.
At the beginning it is said “this video relates to previous video addressing relation of hardness and performance”. Would it not be helpful linking it (if not in video then at least description)? It cannot be found with RUclips search neither by name nor date (as RUclips don’t give precise dates, just “1 year ago”).
Over heating and over soaking will cause grain enlargement weakening the metal bonds. The blade will get hard but be prone to edge chipping and breakage. The condition is visible to the naked eye. Break the blades. The bad ones will be less flexible and the grain will look course and chunky where it broke. A well hardened and tempered blade will show the appearance of fine grey velvet and be considerably more difficult to break.
Sorry one detail I forgot to mention was the steel is 1084. I knew I was forgetting something 😂
you didnt, you actually mentioned it around 14:52, great vid tho!
Actually you did at exactly 14:00 and 14:55 even though you didn’t explicitly say earlier that’s what these knives were made from.
1084(AISI) - Simple carbon steel, low wear resistance, decent shock resistance.
Manufacturing Technology - Ingot
Country - United States USA
No, you mentioned it at the very end and my ears picked up on it. You just didn't have it on your comparison layout paper. It's the same steel I'm working in right now while I can get it. The 1080 series seems to be one of those blends that is only around here and there like D2, W1, and W2 were when I first started forging blades.
Ha! I meant to mention at the beginning..oh well glad its in there somewhere though 👍
What I learned from this experiment is that even if you are a professional knife maker who does a month long experiment there will always be a 16 year old Redditor in the comments claiming to have a more informed opinion.
ALWAYS! And they just can't seem to help themselves.
I even had a guy tell me I was "using the wrong steel to make a straight razor and razors need to be made out of stainless" (I make razors out of 1095, W1, and W2) granted they then admitted they didn't know what W2 even was...
I seriously wanted to slap someone through a computer screen.
Just had to remind myself, their just an idiot... idiots happen... its part of the human condition.
As a 16 year old redditor, I'm jealous of his forearm muscles.
@@LostLargeCats Yea I've only got about 20 minutes of sanding/grinding/polishing in me before I'm done for the day. XD
Basically, this is what I have always heard. HRC goes to edge retention. Proper heat treatment (temperature and tempering) goes to the toughness of the blade and how well it can take impacts and lessens the chance of breaking or failing during usage. To me heat treatment is all important. So a 57 HRC might be my choice over a 62 HRC I can sharpen a knife with a pocket diamond stone or ceramic rod even in the field. What I can't do is replace one in the field that breaks.
Exactly! His statement: "When people talk about performance they are talking about edge retention" really frustrates me because it's too true, when it shouldn't be. People these days obsess over edge retention and they get overly brittle and impossible to sharpen knives.
@@christopherrowley7506 Bought a chefs knife once that was so hard i could not sharpen it in a normal way. It ended up being used in the garden :D
@@baadtaste1337 surgical steel
@@mikeries8549 When a knife is sold as being made with 'surgical steel' without being any more specific, that almost invariably means that it's made of 420J2 stainless (or nearest Chinese or Japanese equivalent). 420J2 is about as soft as a steel can be and still make a useful knife. It's sold as 'surgical' because it's extremely corrosion resistant, and therefore ideal for surgical instruments. it's more likely that this 'unsharpenable' knife is made of what would be considered a 'tool steel'.
Yeah, this has always been my understanding, since my interests lie more towards swords and other weapons as opposed to knives meant as tools. For a weapon, you'll often even prioritize durability over sharpness - a slightly dull sword is better than a broken one - so proper heat treatment is very important. It never occurred to me that for tool knives the priority might be reversed, but I guess that makes sense.
Most thorough, most underrated, most professional “knife and steel reviewer” knife guy on the internet for actual testing. You and Larrin Thomas are doing God’s work. Thank you. Been watching for years and I go back to watch any that I missed.
The answer to the quandary is obvious. The badly treated knives lacked handles and were therefore cold. Which meant they were shivering at the same frequency as an oscillating tool which caused them to appear artificially sharp
Clever! Love it.
Uma...
The poor knives exposed out in the cold 😔
Brilliant deduction, is your real name Watson by any chance 😂
Poor-mans' vibro-dag.
The trouble with heat treatment from a consumer perspective is that it’s hard to quantify. Someone can tell me that Spyderco (for example) does an excellent job with heat treatment, but someone like me doesn’t really know what that means. Hardness, on the other hand, can be tested with a fancy machine like yours and listed in the specs.
I’m no metallurgist, but if I’m choosing between two knives I’m at least smart enough to know that 61 is higher than 58. Most people wouldn’t put the effort into understanding the intricacies of heat treatment even if companies presented it as plainly as possible.
In other words, while heat treatment is likely just as important, hardness numbers still make more sense for layman knife shoppers.
Bzzzt. White iron can be 65 Rockwell, but would be a rubbish blade. Relying on hardness alone is misguided. It's like only relying on the miles per gallon when buying a vehicle.
@@OllieVK exactly. Some steel at 58 HRC will be far superior to another steel at 63HRC for example. Also two steels with the same hardness will be entirely different in performance, toughness, edge retention etc. What matters is the specific steel being used as well as the heat treatment.
Well, I've always heard one of the best in the industry is Buck, the whole Boss Heat Treat thing, but I sent a 110 in under warranty because the tip broke off on me. Of course, I'm hoping I had a lemon and I'll never worry about that again. A month later another Buck 722 Spitfire I had broke, the internal mechanism snapped or something sent it in, haven't gotten them back yet, but totally rethinking Buck.
@@geico1975 probably something you did.
As a metallurgist, if someone tells me that one is 58 and the other is 61 I would assume both could have come off the same load. We don't heat treat to a single hardness. We heat treat to a range. Even a hardness test block has +/-.5 HRc uncertainty.
So glad to see you back on RUclips. Thanks for doing all of this frustrating work for all of us. You really do a great job of simplifying tests and explaining it to your audience.
This is just based on my experience and own personal research but likely the reason why all three of the knives had similar edge retention is because in reality what you're testing is abrasion resistance which with a more basic carbon steel like the 1084 that you were testing with, it pretty much just comes down to the hardness (and edge geometry, which was identical) of it which all of them were nearly identical. Toughness, strength, and apex/edge stability are much more open to variation depending on the other specifics that come along with heat treatment, which is exactly what your testing showed. Honestly, these results didn't surprise me at all, the results reconfirmed prior conclusions I've made. That's why HRC is just one indicator for a good heat treatment and isn't the only way that a person should be evaluating purchasing a knife. Videos of real world testing actually demonstrating the edge retention, toughness, strength, and edge stability are the best resource.
Yeppers. 1084 is a pretty simple steel. Going to A2 yields much greater abrasion resistance (edge holding) because of the wear-resistant complex carbides formed, but heat treating is a little trickier - you need to watch your austintizing temperature and temper to Rc58 to get a maximally tough blade. If you're going to put all of that work into a blade, use a good steel and have it properly heat treated.
This was extremely well done. Interesting to say the least. I’d love to see more vids like this bud
Can you harden a knife by magnetizing it for along period of time ?
@@Enes-wj5xq no .
@@Enes-wj5xqi dont think so, but it probably becames magnetized itself.
I tend to buy knives with higher claimed HRC. The chipping issue is something the OEM's tend to discount as ____________ steel is difficult to work with and prone to chipping.
Maxamet knives are a good example. I purchased two identical knives, one chipped like mad, the other ZERO issues. I sent the chipping knife back to the OEM and was told the Rockwell was "within spec" good luck with the knife... The chipping issue eventually sharpened out. The knife still has damage where the chips were too deep to completely remove. (waste of knife steel, only cosmetic issue.) Thanks for the video, excellent work! : )
Man, you seriously know science, especially after including the exceptions and disclaimers. I love your approach on steels and their properties, and your channel of course.
Great experiment. So, Edge retention and toughness are somewhat independent of each other. That is very valuable information. Thank you for posting!
Yes exactly👍👍 two different things 🙂
I have Absolutely NO IDEA WHY, but You are one of my Most Favorite Channels!!! Keep up whatever Magic you do in your videos :)
Dude you rock. So many people treat (no pun intended) this topic as yes/no when there are lots of maybes involved. To say nothing of whether the knives get used hard enough to discern a difference. Bravo
Thanks for an excellent video.
An interesting test would be to take the knife with the poor heat treatment and re-treat that knife with the good heat treatment to see what effect you would get. The long and hot initial treatment would cause grain growth, but the quench might set up the microstructure to have a better grain size on a second heat treatment. The other possibility is that the prior austenite grain boundaries are already established as large grains and that you wouldn't fully recover the grain structure. Getting the steel back to where it should be might require annealing, rolling, and heat treating from the beginning. All of my classes in this area were too long ago for me to remember what the answer is.
You did a good job! Hardness determines edge retention and abrasion resistance. But grain size determines toughness, in choppers, axes, and swords heat treatment is key to the performance of the blade. I have had poorly heat treated blades snap, much sooner than a properly heat treated blade.
Another point is that you can get a thinner edge (more acute angle) with a tougher steel, without getting chipping. A thinner edge INCREASES edge retention. So the truly telling test would be to grind the 3 knives to an angle where they don't chip or roll on normal cutting tasks. Then see how the edge retention compares. (follow up video? *wink wink *)
You are 100% right . The problem with in the knife community is there is alot of people with only 25 to 30 % of the knowledge needed to have a opinion that is relevant. that being what they read on a data sheet that show what a steels maximum hrc is but they don't understand that data isn't realistic as even if you do a heat treat perfectly it doesn't mean that you are going to reach that hardness or that max hardness doesnt translate to optimal performance. And they don't understand that as a knife maker we are trying to not necessarily to reach optimal hardness but optimal balance for the steel we are using and for what the knife is going to be used for . And these same people if the steel wasn't marked they wouldn't know the difference between say s30v and 1095 . Same goes for alot of knife reviewer who drive buying preferences in the edc and knife communities.
Great Insight!
I do think that for the vast majority of knives, hardness is still a top priority. But, for the vast majority of knife consumers, there still needs to be a toughness balance. Since knives are often abused, dropped, thrown around, etc. A full flat ground 1084 steel blade at 63rc and 0.010 behind the edge would make a great cutting blade but don't drop it or open a paint can. Most knife buyers aren't knife people and expect one knife to do everything. 🙂
@@OUTDOORS55 very . True what I'm seeing is people that watch a bunch knife reviewer content and then want to question why I'm not using 20cv or the like and how come I'm not shooting for 63-65 hrc . And then spend a hour trying to explain to them that yeah it's great steel but not in every application and that I'm trying to strike a balance of maximum toughness with still maintaining decent edge retention because sharpening is always cheaper and easier than a blade that breaks if you drop it or a tip comes off trying to remove a staple .
A thoughtful video with more evidence and detail than most. Keep feeding through useful stuff like this please. Appreciate your channel
This was amazing. It confirmed a few suspicions I had too. Thank you so much for going through all this effort. It would've taken me years to get this amount of experience.
Super glad you did this video. A few of my first knives were quenched way too hot and I've been really trying to get my heat treatment sorted
Shit I’ve had a string of good ones and really shitty ones. I don’t know what’s going on
Hey there, great video!
I wanted to add a little thought to the discussion that you didnt mention in your video. I believe it is wrong to reduce the knives performance to edge retention of the blade where harder means better. By following through with that thought, the best knive would be a knive that has not been annealed at all.
Your findings do prove that there is a difference in quality that is independent of the hardness value, after all nonne wants a kitchen knife to break upon cutting into a bone. Wich could happen with a knife that is equally bad as the third one.
But on the other hand i do not believe that it is possible or sensible to try and find a metric to measure the quality of the heat treatment, since the manufacturers of quality knives have figuered it out anyways and the manufacturers of bad knives (i.e. the 26$ damacus knive you teste) lie about their products anyways.
I believe the current system, where we get an information about the hardness and assume that it has been heat treated correctly, is flawed but there is no realistic benefit for the average consumer to change anything about it.
Btw i love that you try to test things, that are currently measured by feelings and subjective means, in a way that is as scientific as humanly possible. Keep up the good work man!
Great video! It would be interesting to compare toughness of a well heat treated knife at 61 HRC with poorly heat treated knife at 58 HRC.
Or vice versa.
Unfortunately the relationship between toughness and hardness is not linear and quite steel specific. The poorly treated knife at 58 could be notably less tough than one at 61 with a good treatment.
58 HRC is not poorly heat treatment at all!! 😂
@@oldeays5085 depends on how it got there. Pull out of the fire/oven and quench and you can get to 58 without even tempering if you mismatch the steel and the quench.
Toughness will always be worse in the poorly heat treated knife regardless of the HRC.
Very impressive. So thorough. Full comprehension of theory while taking practical to maximum. The edge retention testing done here is supreme.
Great testing and discussion!! I fully agree, that’s why I don’t get excited about overly hard steels, unless they are also tough… pure edge retention only matters if you slice cardboard or rope all day in a controlled manner, but if you start using a knife in a realistic way, who needs a fragile blade that will be difficult to resharpen and strop? Favourite tool steels would be m4, k390, favourite stainless would be cpms30v… looking forward to trying out cruwear and magnacut, don’t care about 15v, s90v, m390 unless it’s heat treated to perfection, also don’t care about 110v or maxamet
Great video and great explanation. Thank you and congratulations.
The main problem here is that, when you buy a knife, you will never know if the heat treatment was made well, good or bad... Only if you abuse your knife to the breaking point.
Very interesting results. Not entirely what I expected. Thanks for all that hard work! I'm sure it was a pain in the drain, but we're all more knowledgeable for it.
Interesting results, toughness definitely matters for chipping on the edge. I imagine the results for edge stability in super steels would be interesting.
Very fun, practical testing to show the differences created from bad heat treating.
What’s poppin larrin
Bah gawd that's Larrin's music!
Came looking for the Larrin stamp lol
I bet that nerd that made magnacut would find this interesting too.
Interesting demonstration, definitely food for thought. A lot of trust goes into the purchase of a knife. I'm very careful with my good (expensive) knives because I don't want to mess up the finish, even knowing the knife is suppose to be very tough. How a knife cuts and how often it must be sharpen is about the only way a consumer can get a sense of whether the knife is satisfactory.
I suppose if a knife manufacturer did a poor job with their heat treatments it would eventually get out thanks to social media. They have to do a good job to protect their reputation id they want to stay in business long term.
I'm just learning about all of this, your work and demonstration made it clear and easy to understand.
Encouragement and props on what you did and shared.
Outstanding job!!!
Really well done video!
It shouldn’t be much of a surprise that these all had the same edge retention. Regardless of crystal structure, HRC directly correlates to abrasion resistance, that’s effectively what it measures. Harder things will resist abrasion better than softer things. The grain size, which is the only variable here shouldn’t effect how the steel wears in a pure cutting application.
Hacking through some boards would likely show more micro chipping and therefore faster wear on the poorly treated ones though.
For tool steels (slightly hypereutectoid alloy steel) 3rd critical point is somewhere arround 860 degrees centigrade. For quenching you want to bring it above critical point 1 where it starts austenitizing (around 790 degrees centigrade) but under 3rd critical point where grains start to overgrow from heat. Depending on the temperature you have to soak it for a different amount of time to fully austenitize - lower temps require longer soak, at higher temps grains recrystalize faster and actually can overgrow also if soaked too long despite being within ac1 to ac3 range.
For 800C 10-20 minutes is very correct.
870C might be above ac3 already, so it's rather a no go zone, but you might get away if you just bring the piece to that temperature and quench without any soaking.
980C for 40min - I'm more than very supprised the blade didn't shatter into million pieces at quench. You can see after breaking how swollen the grains are from overheating.
The moral of this experiment is for a given steel, hardness comes from crystalline structure while toughness comes from crystal grains size?
This was a great, down to the bones kind of video. I found it especially helpful since I'm currently using only 1084 and really trying to pin down how to get my best results with it. When I worked 1095 years ago out of an anthracite coal forge, all my blades failed because of grain growth. I just couldn't give it a steady soak without going too hot at some point and the grain looked like that moldable sand kids play with. Total disaster for me. I'm trying to focus now on maximizing durability. I'm getting ready to make a knife for my little nephew for when he goes out fishing or hunting with his dad, and if he's anything like I was as a boy, he'll need a blade that can hold up to um,...'rough' treatment 😉👍
if you're heat treating in a forge, you'll need to heat the steel and not the forge. The advice to try to make a forge perform like a furnace is bad advice for simple stuff. If you can have a hot spot at your burner or burners and the ability to move the blade in and out of it, you'll get no grain growth with 1084 and 1095 if you do a low temperature pre-quench, then do thermal cycles - pull the blade out of the forge and let it cool to black each time and then heat only to nonmagnet plus a little bit of a temperature overshot as much as you can get one in literally 10 seconds and then quench.
You should end up with finer grain than you'll see pictures of anywhere else and nothing unusual in the structure of the steel.
if you use 1084 and overshoot temp once after the thermal cycles "just to be sure it's hot enough" for 15 seconds, the grain growth will double in size. 1095 is a little more forgiving, but it doesn't have any real margin to give in toughness.
You can practice the thermal cycles by overshooting temperature on a sample for 15 seconds and examining it vs. something annealed once and quenched just after nonmagnetic. The latter will double in size grain wise. Take magnified pictures of the grain, then do thermal cycles with the large grain sample and bring it back to grain smaller than the part that you intentionally didn't overheat. That gives you a very good idea of what you're seeing in forge by looks and by time and how much it affects grain.
You'll want to take an offcut and do this with everything you'd like to use. 80crV2, for example, suffers no visual change after a 15 second high temperature overshot. That doesn't mean the intentional overshot past just a little is a good idea, it just lets you know what you're dealing with.
If you want even heat in a solid fuel forge, place a thick walled (thin walled works too) pipe in the coals and bring it to temperature, then place the blade inside and the radiant heat will heat it up very evenly.
Watch larrin's video on heat treating with a forge. Just only to magnetic from a normalized blade. If it's not magnetic it's hot enough, no matter the temperature, if starting from normalized steel. You don't get a huge range of hardness value this way, though, so you have to choose the steel for the task. 52100 will be hard as hell but not tough enough for a sword where 5160 would be a better choice.
Great video. I think this kind of stuff is extremely interesting. Thanks for sharing, always looking forward to more of your content.
Glad to see you posting again
Upset I wasn’t notified for 7 months,
but glad I’ve got a bunch of stuff to watch now
Interesting results - thanks for taking the time to film and share.
Very educational. Most folks would focus on the hardness and not consider toughness. For knives that are used in the great outdoors and need to be dependable, toughness matters. Thanks for taking all the time to do this, and for sacrificing your arm hairs in pursuit of knowledge.
These results make perfect sense.
Wear resistants as far as I know is a quality of the steel, and the hardness.
Toughness is greatly enhanced by reducing retained austentite and when a steel is soaked at a higher temp longer it can increase that pesky brittle stuff. At the same hardness and wear resistance the knives should all slice the same. If your chopping however I bet chips would show up fast in the poor heat treat. Also I bet the crappy heat treats lead to less ability to flex when in a bending test. Great job showing how toughness and edge retention are manipulatable factors and how we can improve our outcomes
I've been watching your channel since the start and just wanted to tell you how much better your knives have gotten with all the experience you've gained. Just wanted to pass that along. I really enjoy your videos, keep it up my young friend.
My understanding is it's a matter of finding the balance between hardness and toughness. For annealed O1 Tool Steel which comes at RC 45 (how you normally buy it from a supplier) that amateur wood workers use for making chisel blades, plane irons, etc., one is supposed to first shape the blade while leaving the cutting edge about a 1/64" thick to ensure carbon retention, then heat the final ½" to ¾" or so of the working edge to 1,500º F then immediately plunge it quickly and completely into a container of enough oil (motor oil smokes, vegetable oil does not) so it doesn't catch fire, which gives it a hardness on the Rockwell scale of about +-75. Then it should be put in a 350º to 400º oven for 30 minutes to an hour to be annealed to an RC 60/62-58/60 respectively. Too hard is brittle, meaning it shatters when stressed; too soft and it won't hold an edge. The trick is in finding the balance between too soft and hard enough to take and hold an edge w/o shattering.
There is always a balance. O1 is a deep hardening steel, meaning it has a slow cooling curve for martensite formation to occur. Im not sure o1 is a great steel for home heat treatment unless you have a temperature controlled kiln, due to the carbon needing more time to dissolve at austenitizing temperature. 1084 would give more consistent results if using a forge. Thanks for the comment 👍
I am not into knives, per se, but I find your videos to be very informative and enjoyable. Nice mix of facts and reality.
Interesting video!
Perhaps they all performed the same in the edge retention test because your tests were focused on abrasion resistance type tests, or is that correct?
Since there are several modes of sharpness loss that may be experienced during varied practical use, such as micro chipping, or deformation...
1084 being (basically) a eutectoid steel the austenitizing temp has no real bearing on carbide content in finished product, or potential retained austenite like it does in higher carbon steels, both of which would make a big difference in the abrasion resistance aspect of edge retention. In other words, if you tried this with a higher carbon steel you might see some additional significant differences between the samples.
I like your point that RC hardness isn't really the best reference point for blade performance!
And this is why we have destruction testers for "hard use" outdoor knives. The big issue is how easily they break.
People sometimes laugh at the destruction testers, but they bring an important service to us.
For example, a good heat treat will yield a knife that cuts well and can also take body weight "step" loading.
A TOPS knife may have a slightly low HRC and need sharpening more often, but is unlikely to break in the field. The extra insurance comes at a cost. We're usually wishing for the best compromise rather than the safest knife, such as you get from a careful heat treat and a good hardness.
A bad heat treat such as on the many botched Asian Schrade outdoor knives may break in half from just a bad landing when throwing the knife into a tree. So it should come as no surprise that most throwing knives rarely get up to 55 HRC.
A sushi/sashimi knife may be made pretty hard, with a very shallow angle, but it will not see any rough use by a competent sushi chef. It would fail these tests, but no one would notice or care. If the angle was extremely thin, then these toughness issues would become more important.
You're killing it boi ! ! !
Absolutely fantastic content . The way you test stuff in a kinda scientific real world use way is great .
I don't know how else you could test knives any better . Sure all super scientific in a lab etc . But who uses knives like that?
Or totally real world with no empirical data gathered whatsoever . Just gut feelings and personal anecdotal impressions .
Keep it up . Those close ups are stellar BTW !
P.S. How's the house renovations coming along ?
Fattrucker
Great vid really enjoying the content. I think HRC is a good indicator of what heat treaters are looking for when they know the process was done correctly. If your expecting say 61 HRC but you only get 55 you know something went wrong with the process or the problem could be the steel itself. For consumers when buying from a company they are hoping the HRC is a result from a good heat treat process as an indicator of steel performance during cutting. For the typical person who isn't into the depth of heat treat process it's another statistic that they can slap on a label and say "we did the steel correctly" and the consumer will go for it because a higher number is better right. Just my opinion though. Thanks for the great vid and keep making sharp things fun and enjoyable.
5:57 Dude. I'm looking at those images and my mind is blown. Like, you can see the scratch marks from the grinding. But look in between the scratch marks, towards the edge. That is really smooth. Wow! For some reason I was expecting scratch marks all the way down. So unexpected.
That was counterintuitive! Thanks for carrying out the experiment for us all.
This is extremely fascinating!!! Thank you for the time and effort that went into this! 🙌🏻🤙🏻
Another great test and video...appreciate all the work you put into these!
Most of this was above my head, but still enjoyed watching and learning 🙂 Kudos for all the work you put into this. Thanks for sharing!
Well done. I think what you are highlighting the difference between edge retention and toughness in a very understandable way. High performance is really a combination of both.
Thanks for your thorough testing and not just making up wild statements out of thin air!
Great video... so happy I came across it! I am not sure about HRC being equated to a "good heat treat" but I think HRC is meant to be indicative as to the other attributes of the steel. Depending on the heat treat (to my understanding) will help dictate the trade offs between stainlessness/corrosion resistance, toughness, and edge retention. Today, this has become a huge talking point I believe because it attempts to help people compare apples to apples. If I have two knife manufacturers and the same steel if the HRC is at least measurably the same... you have 1 point of true consistency for comparison not good or bad..... just something consistent to view the rest against. But as often said as of late.... geometry is more important than anything else pretty much... but without heat treat do you even have a knife?
Okay, we seem to have established that hardness determines edge retention. However, you also demonstrate that keeping that edge from breaking depends on quality of heat treatment. Great test.
Edge retention without much side load is really just testing the steel and its hardness - slowly wearing the edge down to dull-ish. There would be very little rolling or chipping unless the steel is extremely weak. So you are testing the hardness, especially when they are the same steel alloy.
You got that steel to 60-61 HRC on each knife, so short of extremely weak steel (e.g. walmart knife) they should perform in slow wear mode just about the same.
I did do side load testing. Its in the video
EDIT: You have gone above and beyond regarding the scientific method in this video. Hot damn, sir.
Holy moly, from the first 20 seconds of this video I knew I'd like you as a craftsman if we met in person.
I like to faff about and shave with a straight razor from time to time. Those are the only blades for which hardness is a primary concern for me because they're exposed to no strain. For my utility knives I like it if they keep an edge well, but they need to be able to do it while I'm striking them with an olive wood bastoni or clipping a bone in an animal I'm preparing to eat.
Personal experience, using a knife to pry or use the back for slot screws. Brittle blades break or chip. Flexible blades twist and bend. Sharpening and edge retention. Harder steels don't always retain their sharpness as you would expect but always seem more difficult to sharpen. Flexible steels seem to hold and retain their edge. Are more forgiving of abuse. That it is ill advised to use a knife to open cans, always use a screw driver. Preferably a slot head heavy duty. Never electrical screw drivers.
This video is a piece of GOLD!
So how we sharpen knives is important. I have a Spear (AlexDrow) I would like to put an edge on. After some research it is 420 Stainless a common material for surgical instruments and kitchen knives as well. I have a dremel or I can use a knife sharpening wet stone (more forgiving and lower temperature.) Now if I use the Dremel tool and heat up the edge too much during the adding an edge process I will change the properties of the material. Then it may not hold an edge as long if I change the crystalline structure due to heat. It can also be more prone to rust in the area heated.
It would be interesting to see how they perform in processing a deer. From skinning, to parting and even boning. At least that is how I judge my knives. Hold a reasonable edge and not break. Keep up the good work.
Glad to see you making videos again.
Toughness and hardness are often displayed as opposite ends of a sliding scale. Hardness is a major factor in edge retention. Toughness is closely related to brittleness. A decent knife maker (both mass produced and artisan) carefully balances toughness and hardness while designing a final product. It is easy for the advertising departments to just push hardness as edge retention. That way consumers won't get confused by important information that might complicate a choice. Give one hardness number and say "hardness = good" and the masses will proudly nod in agreement. That's why pocket knives commonly range from $5 to $500. They are selling to crowds who want to be told they have the best, while not wanting to be confused by inconvenient information. It takes a "knife person" to care about the difference.
Having broken a few tips, I now grind my 'utility knife' edges to a point with a more robust angle. Still sharp where needed, but significantly less chance of nipping the tip off. The last 10% of the edge angle is increased by 30-50%. e.g. 22deg progresses to between 29 to 33deg.
I use 1084 vs 1095 because I have found out that the 1084 seems to be more forgiving in heat treatment vs 1095. The 1095 can get a bit more brittle if an error occurs, while the 1084 seems to withstand a bit better.
I kind of wonder if it is due to the carbon content. Higher carbon= shorter crystalization making a harder blade, and during the tempering stage if you start with smaller crystals you reduce the ability to grow a proper lattice in the metal is you have gone outside the perimeters of the steel. Where as the 1084 has a slightly less carbon content which allows for longer crystal formation making it a little more forgiving in the tempering process.
Hell, there are a multitude of arguments that can be made in this discussion, but my choice is a nice 6" blade full tang 1084 knife that I feel comfortable using and have less concerns when having a home blacksmith producing a blade I like.
I think this proved more than anything that1084 is as close to a dummy proof steel as there is! I appreciate how far you took the testing. I don't think you could have done anything different to make it better. With a different steel like 1095 it would have been much different.
I was one of the people complaining early on about the Rockwell testing -- because I just don't think it tells you very much about how a knife is going to perform. It's obviously a multivariate issue with hardness, heat treat, steel and grind interacting in complex ways. These days, I focus primarily on design and ergonomics and don't worry at all about the steel or edge retention. I prefer carbon steels that are easy to sharpen. Blade gets dull, I resharpen.
it would be interesting to see how the un-tempered knife at 65 hardness compared to the other three, in the same test categories. A fair assumption would be that edge retention was better than the others, due to the greater hardness, but toughness would be rubbish
Un tempered blade will snap at once, is like a glass very hard but very weak on elasticity
it would break instantly.. possibly even from just setting it down too hard
@@ThisNameWasTooLon
People think steel is way more brittle than it is.. files are untempered.
Good video. As a maker, I get enraged by the use of the term "edge retention" testing when the test you are performing (slicing stuff like cardboard) is NOT EDGE RETENTION TESTING!!! For crying out loud. It is called "wear resistance". NOT "edge retention". Actual edge retention is the sum of all of the properties, toughness, hardness, wear resistance, apex stability, corrosion resistance (to some extent). And that is why you are getting similar results with all 3 knives in "wear resistance" testing. Those other factors, like toughness, apex stability, etc aren't going to have a noticeable affect when slicing stuff. Grain size plays very little role when slicing into stuff like cardboard, but grain size has a massive role in stuff like tip strength and apex stability.
My conclusions from this are that heat treatment details are more important to blade toughness than edge retention. HRC seems to single handedly determine edge retention (within the same type of steel). I'd definitely rather own knife 1 because it will last much longer.
The reason you got the results you got is that geometry is king when it comes to knife performance. Cliff Stamp cut a lot of cardboard with a mild steel tension bar he ground down and put a coarse edge on. There is a RUclips video or forum post about it somewhere.
You put so much work into these videos. Thank you for all the information!
Love your setup, _especially_ because you're doing "pro science in a garage"... The close-ups keep teaching us a bunch of interesting things.
Given you were aiming for the same hrc and found the same "performance" on all 3, would you say the performance is most linked to the hrc, or to the steel type?
(i.e. if it's the hrc, similar results from other steels at the exact same hrc would be expected; if it's the steel type, then similar results would appear at (slightly) different hrc in the same steel, and different results in different steel at the same hrc)
“Bro science”, not pro.
I'm a retired tool maker, and machinist, and have many factory made knives. All of them start out holding an edge, but the more the edge gets removed through sharpening, the softer the edge gets, to a point were they cut 2 or 3 times, then need resharpening. I've made knives from 01 tool steel, hardened and tempered to 65 rc, and can skin 3 or 4 moose, without needing to sharpen. I certainly would not cut nails with my moose knife, but I'll guarantee it will shave you after you've finished with the moose. If you expect a knife to shave you, AND cut framing nails in half, I recommend using an axe. I don't use screw drivers as prybars, and don't use wood chisels to scrape off paint. I also carry my camp knife that I eat with, cut kindling, rope, and moose tendons. The right tool for the job. In 40 years, I've skinned dozens of moose, deer, and bears, and my skinning knife gets the once over on a 1,000 and 1,200 diamond lap, at the beginning of hunting season, and it's good to go. I heat blue the spine of the blade back to 45-50 rc for ferro-rod striking. My moose skinner has a 3" rad. hollow grind, with 10 degree point,, wide radiused tip ending at 70 degrees to the centerline, micarta grips, and stainless guard, and butt plate. The leather sheath is dipped in melted wax, because 01 tool steel will rust. My camp knife and machete have straight grinds and the leather waxed sheaths, for the same reason. There will be people that disagree with me, but unless you've spent more time on a Rockwell hardness tester, heating and quenching every tool, and die steel available, I'll keep my knives the way they are. I have yet to see a better blade from any manufacturer, than mine. PS, my machete is made from an old, 1940s tree saw blade from a paper mill. I think it is 1/4" thick 4340 high carbon steel, from an 8 ft dia. blade. It cuts nails, and trees.
These results make a lot of sense. The number one factor of cutting performance is blade geometry, with these knives having identical geometry it make sense that they would perform the way they did. I’m not sure you would see cutting performance differences even in catra testing.
Untill further and extensive research, the results apply only to this one batch of steel. Knife performance is more that just edge retention as it is affected by size/weight/shape of the blade/handle, edge geometry, intended usage/purpose, and other factors. Steel performance is also more than edge retention, it includes hardness, toughness, corrosion resistance, and again other factors. Edge retention seems to be mostly related to hardness only regardless of everything else. Great great test! Good job!
Yes the exact results are only for this steel, however the principal remains the same, even with other steels.👍🙂
I agree I think posting hardness values with the knife is important but also actual tested hardness values not what you were aiming from from data sheet. I don’t care that your target was 60 hrc what did you actually get. Hardness values let’s be determine what I can expect from the knife vs another knife in the same steel. If my option was 61 hrc and in a similar knife with the same steel the maker ran it at 58 I would go with the 61 hrc knife. Running knives softer usually tells me the edges are thicker and the maker might be trying to save time and money by running it soft so it’s easier to grind and finish. I just finished a large 4V camp knife that’s sitting at 63 hrc and I’ve had no edge issues in all of my testing with it.
Im wondering if there wasnt much of a difference in the sharpness testing because 1084 is such a simple steel that it doesnt have that much edge retention anyways. (I love 1084 fwiw)
Hard to say.
But this test was VERY well done, i am hugely impressed by the amount of effort you put into this.
Bravo sir.
Finnish Marttiini knives are heat treated to hardness of 55-58 usually max 60hrc. They have used this same steel for a very long time.
It seems that Marttini is saying by doing so, that its just more practical to make them tougher and not change the steel but to make sure they get all out of it with a correct and well controlled heat treatment system?
Marttini puukkos can withstand - 25 Celsius degrees of cold and you can still baton wood with them without any risk of breaking the the blade.
Its just basic 14% chromium stainless steel and its foolproof even in extreme cold conditions and field sharpenable.
They have the much needed heat treatment experience with this steel to get it right with this steel everytime.
It seems that getting the heat treatment right in the factory almoast all of the time is more important than people think.
If the steel is lets say a supersteel like Magnacut but it would be difficult to heat treat right most of the time it requires more precition to get to job done and usually it then cost more. So is it fair to say that it is more practical to use steels that are hard to heattreat badly?
I dont know exactly what was the problem with the DBK magnacut steel in the Bark River knife company knife they used but I remember that it had something to do with the heat treatment.
Its not a surprise that in the beginning the companys dont get it right so well, but I wonder that are there too many knife steels that it would be possible to knife making companys master all of then at the same time?
Less is more sometimes?
Thanks for conducting this experiment. I just learned not to worry about the heat treatment of light duty knives.
I would love to see a video on different sharpening angles and the edge retention and edge toughness for the different angles!
All depends of sharpening angle, if is more open it will last more, if is more close like, 10-15 degree, it will last shorter time
Seems like this makes sense. Hardness is more how it's holding it's shape, but doesn't factor in the "structure" of the molecules/grains (which heat treating properly helps address), so you're able to retain the shape in things that don't strain the internal structure as much...but once you start doing things that rely more in the internal structure, it starts falling apart.
I'm imagining it to being like building a house with proper angles/load bearing/structural considerations vs one that doesn't...it'll get the job done just fine until something tests the structure, and it'll collapse or various parts of the frame that was under odd stress will pop out.
This is good stuff man. Thanks for sticking with it for the duration of your test... im sure it was beyond monotonous at points.
I know this pisses people off in the 1095 fanboy club, but 1095 isn't super tough.
Most companies under harden and over temper that steel and would probably have MORE toughness with simlair edge holding in a lower carbon steel like in the .60-.80 range 5160, 8670, 15n70, 1060, 1070, 1075, 1077, 1080, 1084, 80crv2.
You won't see a good sword or axes in 1095 for a reason.
The extra carbon makes the steel less malleable and flexible. Even with the extra tempering compared to a lower carbon steel at similar hardness.
People really like 1095 though, and those companies can do a mass production in house heat treatment and the wear on tooling and abrasive cost is lower then even if they changed to 52100 at the volume they produce at. It sells, people like it, people know it, why change l guess.
There are also more alloyed, low carbon steels that can make some of the most durable almost unbreakable knives and tools like A8MOD, INFI and 1V to name a few.
One thing which is repeated by many sources is sharpness depends on: edge angle, steel, proper heat treatment. Instead of what I’ve seen on this video I would preferred to see measurement of apex width (hopefully giving some sense of sharpness) and Edge-on-up-tester numbers for blades. To be honest pictures of edge were not obvious self explanatory as said (and forgive my ignorance if I say something which makes no sense. Not an expert). For me knife 1 looked as it had compacted instead of rolled apex (perhaps optical illusion and/or lack of understanding, anyway that is why I mention measurement of width of apex), while 2 and 3 slightly rolled. For me also, edge retention is important but definitely not the most important parameter. The most important is simply sharpness. Only then, once knife is sharp, the question comes how well it can hold this sharpness. If it say it will hold it well for very long time, than well, let maybe make it sharper and see how long than it will hold. If it looses sharpness immediately, well then let’s make it maybe less sharp and see can it hold sharpness in some time which makes it practical and feasible to use (where exact number of this time will very on person, knife, use and need of course). Point I try to make, providing edge retention information, without providing sharpness information is meaningless. So what if some edge will keep its retention if it was perhaps dull (or duller than it could be) in the first place, or width of apex of all three knives possibly identical, just disfigured differently (no wonder all three would have than same edge retention- right?). What it says about holding edge would it be made sharper? Would it still be the same or different? Let say edge 2μm (or whatever) wide with average sharpness of 78g on edge tester holds 30 cuts on rolled towel, after which it decreases to such and such values (or even better, how much it exactly decreases after each cut). Sharper the better as long however as sharpness is retained in reasonable time. What a point of comparing three different heat treatment if each reached same HRC? Is it not a point of “proper heat treatment” to reach higher HRC (within reasonably decreased thoughness and brittleness), so edge can be made to more acute angle it will be able to hold? Again, please forgive me if I have some misconceptions, misunderstanding or other lacks. Not pretending to be an expert. Really relaying information (or misinformation) I absorbed (well or not so well) from watching probably well over 100 RUclips videos now, plus various forums.
Question which bug my mind is: how to identify proper heat treatment in knife which is to be purchased? How exactly (numbers) Kasumitogi or Honyaki affects parameters of knives. ONLY measured values provide sound information. What “better” say edge retention really means? 10, 50, 250% better? Better for acutely sharpen, average or dull edge? If acute, how acute? And so forth…
Somewhat surprised how they all dulled at the same time regurdless of the heat treat. Excellent job on keeping all of the other factors so even for each knife as the tests progressed. Think I have a better understanding of some of the aspects of heat treat and how the edges react to those tests.
Always great watching ur vids. learning something new that makes us wonder and wanna try during lazy winter day. God speed
This gives me hope as a hobby knife maker just starting that my knives have a chance of being somewhat decent 😅
By far my favorite knife marker on youtube. Can't wait to get my workshop set up.
Very practical testing. Every time I watch your videos, I can't help but chuckle at your quote "...Is this even wood..." Thanks for helping me as I'm lying in my recliner at home after having "unexpected" open heart surgery. Maybe by the time things cool down here in NC, I can start swanging my hammer again.👍
If you still have some kind of uncertainty or doubts, I'd suggest seeing if you can do a collab with Project Farm on testing the different blades. He's pretty through and open about his evaluation process and documenting it for everyone to see. Maybe his approach could answer some questions, in either confirming things or making any differences more apparent. Maybe make it a blind study on his end, so all he knows is getting blades A, B, and C - and then do a reveal after the results come in.
Three knives, one with a handle, two without. If you want to be fair and impartial, be fair and impartial. Great video and testing
Absolutely good stuff. It would probably be the best if the knife manufacturer stated steel and hardening and tempering protocols. As well as the hardness. Would give a better if not absolute gauge of the temper of the blade. Probably the most important part of the knife is the heat treatment. Everything else can be corrected with abrasives and effort. Thanks for your time and knowledge!!!
I agree 👍
after being in the "discussion" in the other video and seeing all the work in this one I had to drop a comment for the algorithm at least. great content and video presentation as usual, top notch. was interesting to see real world example and comparison with very low carbide forming steel.
I dunno, maybe it's because my interests lie more towards swords and daggers rather than knives, but this all seems to make sense to me. Blades of equal hardness have comparable sharpness and edge retention, but a good heat treatment makes the blade over-all stronger and more resilient. This is important for edged weapons that need to hold up well to impacts and mechanical stress, and often durability is prioritized over sharpness rather than the other way around, which seems to be the case for tool knives.
The broken knife is Martensitic with the classic tetragonal crystalline structure. The RC point of when it changes is real close to 60. Once your over 1500 degrees it starts to decarbonize making it brittle.
When I clicked on this, I was expecting something to surprise me. The only surprise was that it turned out exactly how I thought it would.
The problem amongst the community these days is that HRC is seen as THE go-to metric for all things "quality". That is not to say that it shouldn't be looked at, but it is somehow the soul focus for most people.
Also, there are many people who buy sprints of the same knife in different steels and consider only one or two aspects of testing and start proclaiming their findings as definitive results. Social media absolutely helps perpetuate the falsity as well. In reality, most people couldn't take the Pepsi challenge with identical blades and tell the difference between high carbon steels and super steels. They simply do not use and test them extensively enough. It is the equivalent of taking one shot from a firearm, getting a lucky shot in the 10 ring and calling it accurate. The ideA that we live in a time where the availability of so many different steels that perform extremely well is like living in a dream world. Imagine time traveling to pioneer times where something like 1080 was the predominant steel and showing our ancestors a knife like they use in well done 3v... It would seem like witch craft!
At the end of the day, it is a deep rabbit hole and it is always fluid in its complexity. The best we can do is try to consider the basics of what is known and keep testing. That may seem like the goal posts are always going to be moving, but along the journey you find your favorite.
Hardness isn't everything as can be seen in your tests or on say Spyderco VG10 at about 60hrc and Japanese chefs knives or Mcusta folders in VG10 at about 60hrc as well but have up to twice as much wear resistance.
But then we see knives from Cultrotech in m390 do 2-3 times better(depending on "regular" vs custom heat treatment and hardness) than Spyderco or Benchmade. A big part is because Denis Frolov/yanhook is a master at heat treatment but that better heat treatment also results in higher hardness, 63.5 hrc for the "regular" and about 64.5hrc for the custom heat treatment.
Those knives don't just perform better because they're harder. They have a better heat treatment protocol which results in harder blades.
Hardness isn't the end all be all but it can give you a hint on performance. M390 at 58hrc isn't going to perform that well because to have it that low there's some off with your heat treatment. Either no cryo, too low of a soaking temperature, too long of a soak, poor quench, too high of a temper temperature, too much retained austenite as a result and you get a steel that performs worse than it should.
Great video. Thank you for taking all this time and effort to make an interesting and educational video.
High carbide forming steels and high alloy steels are another story altogether. 🙂
@@OUTDOORS55 true. Though I think it's those steels(m390 class especially)that a lot of people just concentrate on the hardness number and nothing else.
It was really surprising to see that the wear resistance was the same while you could clearly see the difference in toughness and edge stability. Just shows to show that steels can behave really weird sometimes and not at all to our expectations.
At the beginning it is said “this video relates to previous video addressing relation of hardness and performance”. Would it not be helpful linking it (if not in video then at least description)? It cannot be found with RUclips search neither by name nor date (as RUclips don’t give precise dates, just “1 year ago”).
That blew my mind. I would never have predicted your results, thanks
Over heating and over soaking will cause grain enlargement weakening the metal bonds. The blade will get hard but be prone to edge chipping and breakage.
The condition is visible to the naked eye. Break the blades. The bad ones will be less flexible and the grain will look course and chunky where it broke.
A well hardened and tempered blade will show the appearance of fine grey velvet and be considerably more difficult to break.