"Knife Steel Talk" with Metallurgist: Edge Retention?
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- Опубликовано: 14 авг 2019
- Join us as we discuss wear resistance.
This is the article we are discussing
knifesteelnerds.com/2018/11/1...
We also give a preview near the end of part 2
knifesteelnerds.com/2018/11/2...
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I had NO intention of geeking out about knife steel metallurgy and performance a few years ago, when all I wanted was a knife with better than a 420C steel blade....Yet, here I am!
420HC is a good knife steel , just most have a crap heat treat! Have a read of Cliff Stamps website on stainless steels or Roman Landes.
@@thehopperhopes6365 My Gerber Prodigy with my own grind is freaking awesome. 420hc usa made heat treat works pretty dang good for general use.
@@thehopperhopes6365 it is useable, but 420hc is pretty much the lowest quality steel that can make a good knife and it absolutely needs a good heat treat. There are several steels that can outperform it in just about every metric relevant to knife usage.
With all the testing I've been doing my questions grow everyday. I really enjoy these videos, I appreciate you doing them.
Thanks Gerald
@@FearNoSteel you're welcome
My personal, limited experience is that with woodworking chisels (subject to impact), higher carbide steels tend to lose edge retention once I go below ~35 degrees or so. I definitely notice a difference between 25 and 35.
Thanks for info..! I guess the same goes for knives that are meant to be used for chopping (im getting one in a few days). I just googled angles for axe sharpening, and found 35 to 40 degrees to be recommended. I know samurai swords also needed a somewhat wide angle to cut through armor without chipping the edge.
Definitely some of the best knife content on RUclips! Keep up the great work!
This was a great discussion👌 thanks guys for taking the time, and I look forward to the next one.
Thanks for all the great info and insight you guys are bringing forward to us steel nerds.
Awesome video! When he broke out the spreadsheet and showed the performance gains of changing the blade angle over higher HRC... that was eye opening. Precise edge geometry just became my new focus.
This is a must watch video! Thanks for doing it.
Oh noes calculations! Thanks Shaun and Larrin for taking the time to go through the KSN articles.
I think the reason alot of us really want hardness and think hardness helps, isn't because of edge retention from wear per se. It seems more so because of blunting being our main cause of dulling. Thats why hardness seems to help so much in actual use.
Awesome work guys! That spreadsheet work is great!
Enjoy both of your insight and knowledge! Keep this rolling!
I really enjoyed this one. Great pairing of minds here. Rock on 🔥🤙
Thanks for sharing. I agree with the high carbide steels in that they loose their initial sharpness quick in relation to how long they can cut with a lower sharpness level.
Love these videos, learned a ton from you guys.
Bring on part 2!
WOOO!!! More steel talk!!
1 point of Rockwell = 5% increase in cutting
250 feet of cardboard 58 Rockwell
64 Rockwell = 1.30 x 250 = 325 feet of cardboard (other things equal)
Edge \ blade Geometry has an even larger impact 10 x : )
Great information... Thank you for the video.
The biggest thing is that when you get the steel up to that rockwell, and if you have the toughness, the keenness of the edge can also be improved. The hardness supports a finer edge and you get better retention for even the same bevel due to less deformation.
Great video!!
Thanks for sharing. 👍
Awesome stuff! I'm sharing this with a facebook group. Maybe they'll learn something too. A lot of this I kind of already suspected after years of experimenting with different steels, edge angles and geometries, but didn't have actual data to prove any of it.
Long time no see bro.
Great stuff! This discussion explains why Spyderco blades are very efficient. Maxamet manix 2 LW for example, with a very tall FFG, thin behind the edge, high tungsten carbide content. No other knife manufacturers go to this level.
That Tungsten isn't making the hard WC and W2C in the steel. In most steels like Maxamet, M4, T15 etc it is making W6C which is softer than some types of Chromium carbides.
Big Brown Bear interesting. What is the type of carbide present in Maxamet? CTS lists 22% carbide volume. I was reading on carpenters website " Cobalt improves both the room temperature and hot hardness. Tungsten is included to provide secondary hardness, wear resistance and hot hardness. Vanadium is added for temper resistance, secondary hardening response and increased wear resistance. "
Also, it seems the 13% tungsten is uncommon in most knife steels. What would explain carpenters' reasoning behind it?
Great vids BBB! Keep them coming.
@@BurnDuration it is 13% weight tungsten. Tungsten is heavier so there aren't as many atoms per percentage weight. You can see this in the zknives application when selecting between Mass, Molar and Atoms. The Vanadium is for undissolved primary Carbides, which are the most significant for wear resistance, and some solid solution Strength.(~13.5% predicted volume MC type) The cobalt hangs out in solution and is for keeping the martensite from shrinking when tempering and making more sites for temper Carbides to grow from. The tungsten that is not dissolved stays as M6C /W6C(~3% predicted) The dissolved tungsten hangs out in solution until tempered at high temps which allows the carbon from decomposed martensite and iron Carbides(M3C) to coarsen back to larger M6C (W6C) Carbides bringing the total volume back up to 22%. These temper Carbides help Strengthen the matrix by being the right size( not too small, not too big) to prevent dislocations from moving like the martensite does which causes the "bump" in hardness when tempering +900f°. So it's a complex balance between tempered martensite matrix, primary carbides and temper carbides at the right size.
@@BurnDuration tungsten isn't as sexy in the presence of other Metallic elements, carbon in the metal doesn't have as much affinity to make Carbides with it in the presence of other Metallic elements like Niobium, Vanadium, Chromium and even Molybdenum. That is why tungsten carbide blades are not made of steel. They synthesize the W separately and put it at great volume in a matrix of Cobalt to act as a binder. This way you can get a crazy hard carbide (WC, W2C) that normal doesn't happen in steel due to being a weak ass carbide former. Its weak at making Carbides due to chemistry, Basically the details about election shells between elements. When carbon has a choice amongst other carbide formers tungsten is at the bottom.
My teen challenged me to find a use for his Geometry class info … 😂
Interesting on the 154cm and cm154 having almost no differences.
I noticed that reprofiling my Ontario SK5 Blackbird in 154cm is almost identical to S30V .. It responds the same way to stones and is very good with ceramic rods. I have had to do literally no sharpening since adding own edge . 154cm is excellent steel but ya just gotta have patience with it.
They have the same edge retention, but CPM154 is tougher.
What's your favorite steel at the moment?
I’m totally about the low allow steels now. 80crv2, 5160, V-Toku 2...
It’s counter-intuitive to me to use ultra-hard carbide-rich steel to use for a tool that needs to be abraded at some point.
Had he only the tools. There is a new generation of bonded abrasives trickling in that will left the handicaps.
Hi
In terms of edge retention, What steel at what HRC would you recommend for a kitchen knife (not abused in bones and frozen stuff)?
Could I have your opinion for best stainless and then best carbon knife?
I really don't have time to sharpen them so I would try the extreme:
ZDP189 as stainless
CPM rex 121 as carbon
Is that silly?
Thank you
Those who use their knives know geometry is HUGE. I have always been a bit anti powder steel and just now bought my first premium steel knife.
The Benchmade bushcrafter in S30v has impressed me but not enough to justify the price. I had to reprofile the edge cause it sucks BIG TIME out of box..A pocket knife edge on a Bushcraft knife is a total fail in my book.
That said I fixed it and dang it's crazy tough steel and once you have that edge DANG it holds it nice and keen.
Still with the right geometry esp with wood work it truly doesn't really matter ...BUT that knife is killer looking , I wear it on my hip with a smile . The handle design is awesome once I used the thing for many hours I've learned it just works.
Still 1095hc if cooked right , can float my bushcraft boat just fine.
Hey BBB, what you were saying that lower carbide steels feel sharper in the kitchen longer than higher carbide steels is true likely due to smaller carbides suffering less from carbide pullout. Ive noticed that too. My 20cv knives will stay sharp for longer, but don't have razor sharpness for very long, even as long as my AEB-L kitchen knife. The AEB-L will likely need to be completely resharpened sooner, though, all other things being equal.
Idk, carbide tear out is the first conclusion folks make but I feel it is a deeper subject for another video.
@@FearNoSteel Oooo sweet! I look forward to it.
I think The Science of Sharp has concluded that it's more due to the carbides fracturing in the apex from bending and that causes the apex to chip off early and expose the raw carbides. He was looking at 15v and other very high carbide steels. AEB-L at high hardness can support a razor edge for longer because it's only down to steel abrasion instead of a less tough edge fracturing at the tiny edge.@@FearNoSteel
He said his 15V held the front end sharpness longer than other knives he experienced if you read the comments. He said his article wasn't a conclusive test. Todd said he was simply looking at the failure mechanism of high carbide vs low hardness low carbon stainless. You mentioned AEB-L, I also worked on the HT for the AEB-L mule for Spyderco, it's still for sale on the Spyderco website, doesn't seem like you AEB-L fans support AEB-L unfortunately.
All of us watching this are definite knifeaholics….welcome:)
Do dendritic cobalt Larrin! Thank you for these vids. I wish this came out months ago 😂. Your a legend sir
"knife STEEL nerds" xD nah that stuff is overrated. Hyped up material from the 1990s before they had really cool steels and better treatment knowledge. It's a soft cobalt matrix with huge structures. So it lacks Strength and tougheness and just hold a brittle saw blade edge. Nothing exciting.
Big Brown Bear you have tried it I guess? I want the terrain 365 invictus
I don't use it, nuff said.
I have a tough time telling a difference in real world use. Whether I bring my 1095 knife or my s30v, I still have to sharpen when I get home, 1095 is just easier honestly
I'm a bit confused how he came up with those coefficients, did he just use a system of linear equations from various sample means?
there was a fat stack of ~15 years Catra data from a undisclosed source. The data lined was lined up with the carbide types
from the studies i've researched edge angle on a specific steel is a 40x greater factor at edge retention than steel hardness or steel type.
The problem though is if you have a steel that is extremely soft you can't really push those low angles because it will deform really easy with basic use, it's also difficult to get a very crisp Apex because it will tend to form a stubborn burr due to the increased ductility.
@@FearNoSteel basically anything less than spring steel
@@FearNoSteeljust need to find the Goldilocks hard and tough combo steel to support that thin edge. Carbides are a bonus if they get a free lunch
Don't they have a standard for the sharpening?
Of course
so what angle stands up the best on the test
The lowest, however, 15dps was chosen to represent the best compromise between testing and real world use
Im new to this subject, so please correct me if im wrong - but to me, all this hype about harder steels and edge retention seem a bit "flawed"... To the best of my understanding, the amount of work a steel can do before it needs to be sharpened, reflects how much time you will have to spend sharpening it... So if i use a soft steel knife for an hour, and the same with a hard steel knife, then this wear will require me to do a similar amount of work sharpening it... A "high quality" steel is of course nice to have, but the biggest "benefit" i see from it is that it gives me that sexy feeling of owning a high quality knife (im a sucker for that type of stuff), LOL! From what i hear, even 420HC steel will hold its edge for a reasonable amount of time; so unless i want a knife that i can take on a longer camping trip without having to sharpen it, i dont actually need that premium steel... Corrosion resistance actually seems like a much more useful property (for most people) than having the hardest edge... Of course, if you only use the knife for light tasks, then you may never have to sharpen it... This also means that a higher quality steel can cut tougher materials without ever needing to be sharpened... Do anyone have an idea of what type of work you can expect to do with something like M390 without ever having to sharpen it?
You can buy a car with less gas mileage you just have to fill it up more often.
The problem with knives is that every time you sharpen you take a little bit of that knife away so over the course of 5 to 10 years how much life do you have left if you're always having to stop and sharpen it?
How do cutting edge grinds/angles relate to volume of steel worn away in CATRA testing (per-hundred cards) ?
TCC (mm) = -157+15.8* Hardness (HRC)-17.8*Edge Angle (included angle degrees) + (carbide type/volume) +11.2*CrC(%) + 14.6*CrVC(%) + 26.2*MC(%) + 9.5*M6C(%) + 20.9*MN(%) + 19.4*CrN(%)
knifesteelnerds.com/2018/11/19/steel-edge-retention/
@@FearNoSteel Thanks for the link . . . . Can I assume the image of the worn cutting edge in figure 3-23 is the result of a CATRA endurance test ? Looks to be approximately 0.008" diameter radius, in line with what I would expect for ~1000 gram BESS Score.
Kitchen - cutting board knives I generally sharpen when 20% apex damage reaching 0.001 into the cutting edge. Make my own knives... run 0.005 to 0.006 behind the cutting edge. Always looking for better knife steels but personally believe knife handle designs leave a lot to be desired in terms of ergonomics.
BESS is grams needed to cut BESS test media, it doesn't translate directly to size or what the edge looks like, there can be ragged features that score lower than you would think. Like I said, the edge radius after CATRA will depend on the steel if other variables are accounted for. Rex 121 will not be the same size as AEB-L after 60 cycles at the edge. The CATRA test runs fixed number of cuts, not a pure endurance test.
@@FearNoSteel Understood . . . Looks like I will be building a unique test rig to measure edge stability for the kitchen knives I build. It also will not be perfect, but I am looking to define the combination of down pressure & lateral forces humans use to destroy cutting edges with. I analyze cutting edges under a microscope to understand how humans destroy them. That's far more interesting to me than creating the absolute finest apex which most will destroy in the first couple of passes across the cutting board. My thought at this point is a combination close to 15º bevel with a 30º micro bevel about 0.0005" wide to make a bit more difficult for them to roll the apex.
What is the Apex diameter when the knife stops cutting on the CATRA tester ?
That's different for every steel since the test does not continue until the knife stops cutting. CATRA runs a fixed number of cutting cycles. The knife that cut the most cards after the fixed number of cutting cycles is the winner. BESS sharpness is ~1000g after testing, this certainly dull and not anywhere close to where it started.
@@FearNoSteelVery interesting . . . thank you for sharing your insights. After watching the CATRA video, it looks to be a well thought out design; limiting side pressure & heat build up at the cutting edge. Thinking abrasive qualities of the steel as they wear becomes a real factor in these tests. This test set-up seems to push apex wear well beyond what you or I would find acceptable for kitchen knives.
True, but if you look at pg 81 in "Knife Engineering" you'll see that between AEB-L, S30V and Rex 121 under 10 cycles they cut about the same after 10 cycles they was clear separation. The harder steel with higher volume of harder carbides cuts more cards hence sharper, dulls less and does more work.. It was thought by some folks that steels like AEB-L would show more cards cut initially meaning better front end sharpness, however thats not what happened in testing and that's not what happens in reality if they are all sharpened to the same level. The biggest problem is that you will have people who refuse to use the proper abrasive for steels at higher hardness with harder carbides and then complain about the front end sharpness, also combine that with difficulties and processing those steels and poor heat treatment and you see the systemic issue with low performance edges on super steel.
@@FearNoSteel Yes, I have seen the blame game throughout my life in several professions. My best guess is most either lack the focus to educate themselves or are just plain incapable of learning. I have built custom tools throughout my life to push what many believe to be cutting edge technology to new levels. I am 2 years into the process with what I call Kitchen/Cutting board knives. Set aside my sharpening stones for diamond plates quickly, basically unwilling to chase burs from one side of the apex to another. Grew up in a machine shop sharpening tools for particular tasks.
Outstanding knife steels seem to be available; it's just a matter of picking the best steel for real world use case scenarios. Always confident in my ability make a knife blade, I look to you and Larin for a better understanding of steel appropriate to create thin flexible
& durable knives for kitchen use. Realistically they will need to be easy to sharpen as consumers often have extremely low skill levels when it comes to sharpening anything.
I have thousands of hours in: R&D of knife handle design, creating custom tools to produce them with consistency, accuracy & a level of finish to my standards. The "experts" often provide little to no help, insisting that what you are doing will not work. Just ignore them & push forward with your testing & tool development.
hi i have question about steel its s35vn i have the recon 1 in tanto shape and behind the edge its 0,024 inch and 13 degrees per side and the hrc should be betwean 59-60
i am worried about chiping or bigger chips
how much strong should it be with thet geometry and hardnes ? thenks
That bevel would be HUGE. You sure it's 13dps, they are closer to 17dps from the factory. If your worried, increase the angle. It's a trade off.
@@FearNoSteel i measure it again and the bevel is 0,047 in long but this is after i sharpend it i put my measured number into this www.hackmath.net/cz/kalkulacka/vypocet-trojuhelniku?what=sss&a=0%2C047&b=0%2C047&c=0%2C024&submit=Vy%C5%99e%C5%A1 and it gave me thet the angel is 29 inclusive = 14,5 dps but if the cold steel make the heatreat right it should be relativly strong and stabel should it ?
@@sebastianfaix
I don't feel that is a reliable way to measure the angle. I use an angle cube to reference. "Is the cold steel HT stable enough" idk I don't make them. The answer is "is your user use able to handle that Geometry" if your using the knife like cold chisel than no, beef it up the angle. If used judiciously than the lower the better within reason.
Pretty straight forward, just use it and find out.
@@FearNoSteel thank you very much for communication I appreciate it very much
i utmost chope some wood the hollow grind is kind the same as the CRK so could it bend in the hollow grind while working with the wood ?
@@sebastianfaix no, the crk may have a hollow but it is plenty thick enough to hold up to anything within reason. I don't consider a crk to be a great cutter. The hollow grind by itself is not a measurement of how thick or thin the Geometry is. You need to just use your knives and see what happens and make corrections as you see fit.
The 88th Thumb Up!! Haha how did that Happen :-))
If the abrading media is larger than the size of the carbides, would it cause tear Out? Would something like d2 show better edge retention on something with course or large abrasive particles in it?
Wear is best when they are matched in size. Bigger abrasive grains can "scoop" better. That's why some can sharpen high wear steels with a 325 SiC stone even though the abrasive is softer than the carbides. However shaping to a sub micron high performance edge at 10um can be problematic if the abrasive Doo Doo soft
DR. THOMAS OS THE BEST!! Period...
Someone send this video to apostle P aka Coward !
That dude SUUUCKS
I once had an inox steel knife ,,,,,,,that was impossible to sharpen. After 30 minutes of sharpening, the edge was still round and harmless, not sharp at all. What steel was this?
I have run into this kind of thing a few times! In knives and also in a laboratory situation. The first expensive Japanese knife I ever bought was impossible to sharpen with whatever I had at the time, I eventually threw it away! Later in life I did some metallography work in different labs, and found that solid chromium and a chromium intermetallic (Chromium/Niobium) seemed almost infinitely resistant to abrasion... the little diamond saw everyone uses for metallography would never get through it! The diamond saw will cut up a carborundum stone as if it was made out of candy. I don't think my new friends were harder than diamond!!! But they somehow resisted abrasion. Conversely I've had a chance to sharpen regular Japanese knives that were not stainless, and it was a great experience! The stones cut them easily, left a nice finish, it was over in no time! Unfortunately rust is a big problem here in sweaty FLorida... when someone says a fancy Japanese Stainless acts like Carbon Steel in sharpening, I"M LISTENING!
@@leonardpearlman4017 Chrom-vanadium steels are not good for sharpening.
Seems like he wasn’t to excited to do the interview
Great discussion, but metallurgist guy reminded me of goodfellas quote "he's content to be a jerk")))
Wat?
@@FearNoSteel i dont know Shawn, he's a bit high and mighty lol
@@don0giorgio nah man, he is solid. Larrin is a good friend on mine.
@@FearNoSteel will trust you on that one, havent talked to the dude after all)) Lots of luck man, video was very interesting to watch. Its a shame how little views this kind of valuable content gets. I mean just look at the top 10 trending youtube videos - straight up garbage))
Yes old news. Why are people sending knives overseas to proves something that has been known for 2000 years 😂
This should be prerequisite viewing for anyone in the knife community who leaves a comment to a video.
Lopsided information/passion ratios fuel misinformative posts. Aka the 1st stage of Truth - denial.
Rant begins in 3, 2, 1...
This video is the antidote to steel misinformation propagation by $5,000 knife collection g.e.n.i.u.s.e.s. (grinds edges noticeably imperfect uninformed steel education surely). That's not a dis of knife community channel author. Im describing people who buy knives as habit but don't use knives in practice. Their experience is subjective to the knife's value. If any information appears not in keeping with their expectations - denial while spewing info reestablishing the legitimacy of their purchase.
I had a Super Steel Steve moment when "the science is in keeping with the knife channel tests" reveal happened.
The science was always going to corroborate the rope cut and cardboard tests because they're being performed unbiased and with integrity. The misinformation starts when someones knife underperforms (truth) and the denial of the result is substantiated by lack of scientific blah blah. The science will confirm THE RESULTS. Lol How couldn't they? If they didnt match then the test wasnt fairly conducted and I sense all the knife channels are fair and love the knowledge regardless of the winner.
The elephant in the room is there is NO INDUSTRY validating the creation of these knifes. I was looking at Benchmade Gold class knives and couldn't stop laughing. Beautiful, high quality material, fit finish, opulent treasures. The opposite of EDC. Knives that may never cut lol. That's not even custom. But that's not even the problem. The problem is I'm thinking 92% of EDC has nothing to CUT as an industry practice. Name a job besides carpet installation where you use any EDC knife. Rofl. Ok military, emergency responders, drop ship shipping receiving clerk AND band roadie. I think that's IT. EDC ain't CUTTING EVERY DAY. 93% of PM2 users cut letters open 71% of their knife life and that's 100% accurate to what I guess based on just a feeling I'm likely wrong about but not by double digits, right? See technically I'm not right but I'm scarily near the truth possibly. I may be a statistically inclined savant, wait I'm not autistic. My best knife is a Kershaw Blur though so yeah. My credential.
"yeah, they didn't know what they were doing back then" - I sincerely hope you were being sarcastic. The idea that previous generations were less intelligent /able is rampant in the world today because of the massive technological improvements in the last 100 years. Given the metallurgy and the sharpening technology available to our ancestors, they were extremely clever to make knives preform as well as they did. I would go so far as to say that they got more performance from the steels they had than we do. Starting in the latter part of the last century the average length of time that a steel is considered to be the "best" has gotten shorter and shorter. 1095, 440c, and O1 were top of the heap for a much longer time than say S30V or S110V. I realize that some of these steels have been around for a while but it seems like no sooner does a "super steel" becomes widely used in knives, a new "more super steel" is released. Very few people have an opportunity to master sharpening a steel before it becomes "outdated" in the view of "knife nerds". I love to sharpen steels that take a good edge, are easy to grind, but still hold up to use and impact reasonably well. It seems to me that using a high quality non-super steel and sharpening it often is the best way to always be using a very sharp knife. Most people who insist on top level sharpness ie sushi chefs go this route. Another benefit of this strategy is that by sharpening really often you will learn how to get the most out of your knife.
I think it may have been tongue in cheek. His father was a knife maker, after all.