I normalise my knife 3 times and I was WRONG!
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- Опубликовано: 6 июн 2024
- This video is probably the most controversial out of the whole series with the fact that Graham Clarke busts one of the biggest myths in knife making - normalising / normalising more than once! In this knife making video, Graham explains why normalising more than once is a redundant process and grain size only becomes fine when done once correctly. This video may save you time, hassle and bust a myth in the knife making industry. What are your thoughts? Share it with us below!
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Can you explain to me since you are a metallurgist why when i quenched and tempered my steel the grain stucture stayed the same as it was when i quenched and snapped a piece to look at the grain size?
Regarding estimating the temperature, a friend taught me this useful trick: use a magnet to see when you get up to 770°C/1,390°F, and then sprinkle some table salt over the steel. When it melts, that’s 800°C/1,475°F, the melting point of sodium chloride.
Thanks JHC C for the input.
@@UKBladeshow You are very welcome. I’m still trying to wrap my brain around how your statements In the video jibe with my prior understanding of how new grains start growing at the intersections of the boundaries of the old grains, but I’m getting there. UPDATE: Maxime Regamy's comment below is pointing me towards the difference between normalization and lower-temperature grain refinement cycles, as detailed in Larrin Thomas's "Knife Steel Nerds". I shall have to check that out.
That's awesome too ! Thankyou.
Oh my, I wish I had seen that salt trick sooner. I am new to this and just did my first normalize, heat treat and temper. I did the magnet thing and then guessed at the colors after that. It seems to have worked out as a file cannot work on my blade.
Can we arrange to have Graham Clarke declared a national treasure? Dude is an absolute legend!
I've only been blade making for 2 and a half years, forging for the past year and I've learnt more since watching this channel than anything else!
Hi Terry! I 100% agree - Graham is an absolute legend! We are lucky to have someone like him who is helping the community understand why these myths are debunked and hopefully help knife makers save time (and propane hahaha)!
@@UKBladeshow anything that saves on propane is good with me! My bank balance takes a hit every time I have to order a refill!
@@Bridgercraft cheers Terry! Speak again soon!
International treasure
Graham is an absolute sage who backs up what he says with anecdotal AND empirical evidence! Please feature more of him.
Hi Ivan thanks for the comment- he is savage as well with debunking these myths! Don’t forget to check out his other knife making tips HERE: Knife Making Pro Tips
ruclips.net/p/PLFssspwgISv-q8YPgoAg1XNZYw9YbMkJT
Normalize once eh? Seems this video is using normalizing as blanket term for all thermal cycling operations after forging and before hardening, normalizing is actually something specific, not a blanket term. Normalizing is not just about grain but also carbide dissolution ( above Acm.) So, "30 degrees Celsius above" a typical austenitizing temperature doesn't reach or exceed Acm in most hypereutectoid steels. The purpose of normalizing is not just for "normalizing grains" but most importantly carbides (dissolving and reprecipitating more uniform carbides.) Annealing is also an important step for further carbide refinement that has an massive effect on the austenitizing temperature and time used for hardening which has a huge affect on PAGB and carbon in solution which massively affect whether your high carbon steel blade will be a brittle at the edge or strong and stable even at the same HRC.
Normalizing: above Acm
Grain Refining: Between Ac1 and AcCm
Annealing: Above Ac1 with controlled cooling rate through Ar1 (fast or slow) for desired carbide structures (fine or coarse spheroidite or pearlite) to machine or harden from or use of isothermal holding etc.
These are some of the different types of thermal cycling operations that are done between forging and hardening. Normalizing is one of them, not all of them.
finally, someone who gets it. I normalize once, though if I do a lot of work on something I'll do a normalize cycle then continue and right before the quench I'll do another cycle and then quench.
Thanks Orion! I am no expert myself but listening to Graham just disproves one of the biggest myths in the industry and could help people save a lot of time, money and hassle!
You only need to do a normalization before the quench and tempering for knives. I would recommend a stress relieve cycle after a lot of work as it is only a 500 deg heating to allow stress to move about, instead of the 800+ temp of a normalization. If that hard work means heating to red hot and forging it then you are doing that stress relieve by default.
I am a fledgling blacksmith first and foremost so that's where I come from, the only time I do a thermal cycle more than once is if I work the steel hard and stress it too much, then I'll do a thermal cycle to stress relieve it and continue the work. Though most times one normalization cycle is all that is needed.
So far the best tutorial video's for knife makers / blade smiths. Your detail makes the difference. Thanks from South Africa - Eastern Cape.
Thanks again buddy Happy to hear you enjoyed the video!
- Vinz
Love these videos and all the great information that you are sharing
Thanks and please keep them coming
Cheers MarquesOtto!
That is so interesting! So people (like me) believed in the 3 stage system but the grain is small because the last heat up was the one that made it small. This is amazing thank you
Hey bud. Thanks for watching! And yes, hopefully this video will save you some propane! 🥳
@@UKBladeshow I believe it will
This is great! I’ve never bought into the “multiple normalising cycle” thing, for the same reasons discussed here - only the final one counts. Another great video, and very well explained, as ever! Brilliant!
Cheers Andrew! Nice to see you on the channel again! Speak again soon!
I always thought three cycles was for stock removal. Every time you do hot work you dissolve metal crystals, so I’ve only normalized before hardening quench too.
Thank you for this info, this made what I've seen in my limited hobbyist workings make sense. I expect the quality of my work pieces to improve!
You’re very welcome! Thanks for watching!
Thanks for this lesson, this has helped me understand where I went wrong!
Hi Keith! Thanks for having an open mind but continue to watch other videos as well as learning from all angles can help you become a better maker overall!
I am the founder of H&W Profesional grade throwing knives. Now we do not make knives for using to cut with even though we could. We make knives for no spin and half spin knife throwing. One thing that sets us apart is we do not sent our knives out for heat treat them, i do all the heat treatment myself which I tested, and continued purposely snapping pieces of the 5160 and 80crv2 until i had the process to where I felt I have it to where they do not snap tips or bend. I normalize two times with those two steels we use. Particularly because our blanks we cut out on cnc plasma running off CAD. I have tested with 3 normalizing cycles and the results were not as good nor was the grain structure. Ive tested with one cycle and there was no noticeable difference from two times.
I have a Masters degree in Geology and learned a lot about phase diagrams, phase transitions, packing of atoms, the whole shananigan - so everything you say makes PERFECT sence! I have never forged anything, nor worked with metal, but I find blacksmithing and blade making very interesting. You give those 10 % more understanding of the processes, than any of the smiths online do. THANK YOU!
Hi 👋 thanks for sharing your feedback with us! Lovely to hear you enjoyed the video!
I find your videos as a breath of fresh air the concert we were talking about other ones that I was able to learn in my metallurgy courses and I try to teach some of the concepts to other people that are getting into bladesmithing and so forth. And a lot of what I've learned I've learned from people who knew what they were talking about thank you for putting out such great videos and I love the content
Thanks Little Bear!
@@UKBladeshow you're welcome keep up the great content
i realy wish you weren't so far away , ive started out on this blacksmithing/ knife making journey a few months ago and honestly the places ive been to learn are good but you seem to have so much information and knowledge about it i am glad your making these videos to educate us i think this sort of work is a dieing art that needs reviving, keep up the good videos and ill be following along :)
Thanks dritsy! Lovely to hear your journey in knife-making! Let us know if you have specific topics you are interested in! Thanks again!
- Vinz
I've only just recently discovered this channel, and my god I wish I discovered it a few years ago when I started working with steel, most everything I've learnt has been through making mistakes and trying to rectify them by applying logic, I'm sure you can realise that it's a slow process, however the things I've learnt just from watching a few of these videos is fantastic! I cant wait to try and apply the things that get spoken about. Thank you for sharing the knowledge!
Hi jed and thanks for the lovely comment! Happy to hear you are enjoying our content! Looking forward to seeing you in our other videos too!
Thankyou for defining something I have long suspected. Now I need a pyrometer...I dont make knives often but when I do I want it to work out right...Cheers
Cheers bud!
I have learned a lot since starting to watch your channel. I appreciate your time and knowledge. The one thing I had confused was normalizing and stress relief, I was thinking they were the same thing. Certainly not, since you bring your temperature too a much lower threshold to relieve stress, and higher temperature threshold than quenching for normalizing, two completely different things. Thank you for your knowledge again, to just straighten this out in this Maker's brain. Just my thoughts from a guy in Tucson
Hi Guy! Thanks for taking time to leave us some feedback! You’ll be pleased to know we have more Graham Clarke content coming real soon! I hope you’re enjoying the other knife making-related videos too! Cheers mate!
Seems to be a great resource. Thank you!
Thanks for the feedback Richard! If you enjoyed that, we made a playlist or library of other helpful vids for knife makers:
Knife Making Pro Tips
ruclips.net/p/PLFssspwgISv-q8YPgoAg1XNZYw9YbMkJT
Interesting video, good to have different opinions.
If be interested to hear Grahams thought on powder met stainless steels. I've always wanted to try forging it but never had the confidence to normalize afterwards.
Hi Duncan! Thanks for the feedback! Just in case you haven’t seen it, Graham did share his personal thoughts on powder mets in one of our previous videos: Why 98% of knife makers pick the wrong steel according to a metallurgist
ruclips.net/video/swkZgWWJ8yA/видео.html
Super interesting and informative as usual. One thing that stuck out though: "If your grain size is too fine, it won't harden up properly" I've not heard that before, why does that happen?
Good question mate. I am meeting Graham to film his twist Damascus and his copper San Mai (Cu Mai), I’ll definitely be interested to know the answer myself!
This was the biggest question for me as well
NMTP nucleate from the grain boundaries. More grain boundaries you have (small grain size), more NMTP you have. Aka less martensite
@@sortaja5314 I had to go look up NMTP (Non-Martensitic Transformation Products in case anyone's reading) and I'd not heard of those before. Thanks for the info, I have some reading to do :)
I'm a retired tool & die maker, and , over the years I have made the knives I use to skin moose. My favorite knife I made from 01 tool steel and I hardened and tempered it to 65 RC. I spoke about this on a knife-makers utube channel, and was told that I couldn't possibly have achieved 65 RC, because 65RC is as hard as 01 gets before tempering. I've watched forged in fire show on TV since the first episode, and I'm always amazed at the variety of "EXPERT" advice about heat-treating. I've always used the steel-makers recommended temps, and have relied on a rockwell hardness tester to verify my results. The experts out there make heat-treating sound like witchcraft, so I find it refreshing to hear you dispel some of the myths. Steel manufacturers have very good info on their products, and should be trusted as a source of accurate info. I don't understand why knife-makers don't use their info, but, it seems witchcraft is preferred. Keep up the good work.
Cheers Robin! I appreciate you taking time to share your input!
In another vid I'm pretty sure you said 68 HR C, if you are the same guy of the moose skinner tale ... which I asked for some explanation... make your mind, oh you stranger of the void and new channel
Another great video
Many thanks vince & Graham
Regards
Davy
Hey Davy good evening and thanks for watching!
Fantastic... Struggling a little with 01 at the moment. I can only assume I did not normalize it properly. When I etched the steel I got odd black streaks, like Damascus. Knives are brittle ... Crystals to big?
Brilliant video! Is there an optimal cooling rate for normalization, or is the temperature the only factor? I work in a shop without any climate controls in the American Midwest. There are days when the temperature is below freezing in the shop and days when it’s 90F(32C). Will the difference in air temperature change my normalization process?
For a plain carbon steel it shouldn't make a difference. High alloy steels might need furnace cooling through the critical temperature to avoid hardening.
Are you using a specific steel?
Loving those Graham series of films and his no nonsense approach.
Hi Bernard! Thanks for sharing your input! And yes, Graham is one of those guys that will just lay it out there if he doesn’t feel it’s right! With the intention to help others obviously! Thanks again!
Thank you for this. Great stuff. I could learn all day, and more from this man.🍻
Hi Jackson! Graham is an absolute legend! Thanks again for watching!
No problem. Novice here, but I'm coming up on my first year as a full time Smith. I lean towards a mix of traditional and modern mix. I love the entire craft. I'm growing fast and need all the knowledge I can get. I one day would like to do "the heratic" level stuff lol. Swords got me into it, but my big passion is tool building. It may sound cliché, but blacksmithing is saving me. Great channel, and hope to see more from you guys. Look for more banter from me 😆
@@JacksonDunnoKnows cheers man! Speak to you again soon!
Finally debunking the myth! I tried to understand the mechanical/chemical reasons for normalizing three times and I just couldnt see why three times would be better. I think it might be because people do not soak long enough per cycle, then you only get uniform grain size on the third cycle. Love this series!
Hi Pim! Nice to see you again today mate! And yes, I am so happy that Graham is sharing his knowledge with all of us - helps us improve the way we work and also saves us some propane 🥳🥳🥳
Hi Graham . You well? I met you in Edenvale a long time ago and bought quench oil from you. My question if I may. How long do I need to soak the steel at the recommended temps? Carbon and Stainless. Thank you, sir.
Very helpful video. Thank you.
You’re welcome! Thanks for watching again!
I have been on one of Graham’s weekend knife making course and this man is a god at making knives
Hi Clive! Excellent! Thanks for watching and hope you’re enjoying the series and our other videos!
I agree with Graham Clark. Steel should only need to be normalized once. So many others on you tube say do it 3 times at lowering temperatures but that makes no sense. I was hoping to find a video where you talk about tempering. How many temper cycles do you recommend ??
Good question! You’ll be pleased to know I will be seeing Graham in a couple of weeks so I’ll ask the question for you!
@@UKBladeshow I finished my knife and got good hardness (file test). I tempered 2x at 400F for 1.5 hours each. I'm about to sharpen it so we shall see how it takes an edge.
The completely accurate but not very helpful answer is: “it depends”.
The idea of tempering is the relieve some of the stresses caused by the transformation to martensite and restore some toughness (with the balancing act of how much you trade toughness for hardness).
A plain carbon steel is fairly simple - if the quench has gone right you’ll have a fully martensitic structure. Pick you temperature to get the hardness you want and leave it in for the right about if time (30 min + 30min per inch of thickness is the general rule of thumb). Since it’s a fully martensitic it’ll all be tempered so a single temper will do the job.
High alloys steels are a bit more complicated. As alloy content goes up, you’ll still have pockets of untransormed austenite (retained austenite). Retained austenite isn’t very stable, it just needs a little bit of energy to finish transforming into martensite - energy it can get from tempering. So first temper will temper the original martensite and transform the retained austenite into untempered martensite. The knife or part will then need a second temper (and possibly even a third if there was still retained austenite left that transformed in the second temper).
There are more exotic steels that need multiple specific tempering cycles to get the best out of them like precipitation hardening steel but as far as I know they’re not common knife materials.
A way of cutting down the required number of cycles is doing a cold treatment right after quenching. Putting highish alloy steel into the freezer for an hour or so should help all the retained austenite to transform so you’re dealing with a completely martensitic structure like a plain carbon steel.
Does that help at all?
Is there such a thing as differential wear resistance? Like a katana has differential hardening, or how case hardening creates a carbon gradient that is differentially hard, is there a way to have one side of a steel wear faster than the other?
Wear is complicated in the detail but it’s almost universally true that the harder a material the better its abrasive* wear resistance will be. And you gave two good examples of differential wear resistance - the hardened edge of a katana will have better wear resistance than the softer back and a carburised surface will do better than an un-carburised core.
There are other ways you can improve wear resistance on some areas but not others - shot peening, flame, induction or laser hardening, selective nitriding or boronising, various types of coating. It depends on material and application.
*most people think about abrasive wear when they think of it. There are other types (adhesive, tribo-chemical, rolling contact fatigue etc) that need other properties to mitigate against.
Great video. I get quite good results on my grain structure by normalizing 3 times, could you do a video making 1 , 2 and 3 normalizing cycles, quench and temper and breake the bars ? If you ttalk about grain size without showing what size to expect from this process its not very clear or useful.
Hi Jose. Thanks for the comment. Graham explains why your third normalisation is the only thing that matters in this video. Sorry if we didn't have a microscope to show you the results but Graham does heat treatment as a profession for several decades now. I hope that helps.
sawe this somewhere else recently and tried it out, it does indeed work exactly as described
Cheers Andy! Happy to hear you second Graham’s comments!
What about differential heat treating/ edge quenching vs full quench?
Not covered in this video. Maybe they'll make another about that.
You'd not go wrong looking up 'jominy end quench' testing. There are quite a few websites and no doubt a few videos that'll get you started. If you know what steel you have you'll be able to predict how much of the blade will harden.
Again really interesting. I’ve had the opportunity to get lots of advice from lots of different people. There really is two camps when it comes to the heat treat. Normalise once or repeat three times decreasing temperatures. In my experience I’ve done both. I prefer doing it once myself. It really boils down to experimenting, getting a few bad pieces and a few good pieces. Then figuring out what you’ve done and what works for you.
It boils down to what works for the steel. Your 1095 is no different to mine. Science.
Thanks ThreeCat! You are right, to each their own but I hope Graham’s knowledge will allow people to have the understanding to choose whether they would still want to do more than one normalising cycle without understanding it’s purpose and how it works - may save a lot of time and hassle for others!
Where I live there is no such thing as 1095 or 80crv2 from the steel suppliers that I can find. There is buckets of O1, D1 and D2. So I read the specifications, more out of frustration and hello there is the Vanadium content as a percentage. And there is the normalizing temp ranges and the hardening temp ranges. Even specifies the quench oil and temperature of the quench oil. HRC range etc etc amazing them specs takes all the guess work right out of it.
One thing I never understand is why the quenching temperature is described as "cherry red". isn't that far too cold? Another way to check if its at the right temperature is to see if a magnet sticks to it. But when I try that, the piece is magnetic until the steel is orangish in color, definitely not describable as "cherry red". So which is right? Sometimes I wonder if I am heating too much before quenching...
Also, if the crystals grow over time as you heat your piece up (prior to quenching), then does it mean that heating a piece as quickly as possible and quenching will result in small grain sizes? So something like an induction furnace that gets steel hot in seconds would be ideal if you want smaller grains right?
The hardening temperature will depend on the steel, I'm afraid to say.
Cherry red (about 700C or so isn't it?) does sound a bit low especially for a high alloy steel. If the steel is still magnetic then it's definitely too low.
If you really want to get into the weeds, you could look up Time Temperature Austinisation charts (if you can find them for the steel you're interested in). That'll tell you how long you need to hold a steel at a certain temperature for complete transformation to austenite (the higher the temp the shorter the time - also thickness dependsnt).
And yes holding at a high temp will cause grain growth and the higher the temp the quicker that'll happen. The ideal is for full transformation then quench as soon as you can.
The color of the steel is dependent on not just the temp but also the surrounding light. A yellow glow in a poorly lit shop may look a dull orange outside in direct sunlight. You can still use color. You just have to know what your steel looks like in your shop.
Yes! Great video and glad Graham mentioned stainless steel aswell.
My question to Graham if he reads these comments is; would you still recommend a normalising cycle if you're doing stock removal from annealed materials? Thanks 👌
Following, I'd like to know this answer too!
Brilliant question love to know the answer myself
I would say no, as your not changing the internal structure of the material and it’s already annealed. If you wanted to change the grain size then yes. I’m just a welder though could be wrong lol
He does another video on this very question and he does recommend it even for stock removal
Larrin Thomas did good work on this, especially for finnicky steels like 52100. Yes ! Normalized microstructure is much easier to dissolve than deeply annealed material from the mill. So especially if you forge heat treat the normalize helps a lot because it drastically reduces the needed soak time before quench without the threat of grain growth.
Well I’ll tell you what I will say that this gentleman is just about the roughest toughest routinist tootinist and shootinist metallurgist I’ve ever known and if I ever want to heat treat a piece of steel the right way I know who to go to !!!thank you sir for your time
🥳 thank you for watching Kenneth and glad you enjoyed Graham’s video! Hope you’ll enjoy the others too!
Mr Google gets it wrong lots very informative and well explained old fella
Cheers Kyle!
Can you lose carbon when forging?
This man is spot on and an absolute metal working genius. To have his knowledge at hand should be any blade makers aspiration. Einstein of Metallurgy. Thanks RUclips!
So if once is fine for normalizing.
Is three times necessary for tempering ?
For instance 01 tool steel for knife hardening needs to be tempered 3 times for a half hour at perhaps 200C for a Rockwell of 60 to 61. (So I've heard).
OR is that perhaps once too ?
It depends on the steel, I’m afraid. There are very good reasons for double or even triple tempering high alloy steels. I had a look at O! and a single temper will do the job.
With 8760, does it come from the mill with a lager grain size and should be normalized, if I'm not forging it? Also, how slow do you want it to cool during normalization?
Without knowing the supplier or the specs it was sold under I don't think anyone can answer that, I'm afraid. You'll have to ask the people you got it from.
I couldn't find a data sheet for 8760 but found its composition. Based on that I'd have thought air cooling from normalisation would be fine.
Well a very renowned blacksmith, Jerome Truchard, teacher in an apprentice university, told me that he did his normalization during his forging. When he's done with the overall shape, he heats up the steel to a normalizing temperature, and hammers the finishing touches. Apparently it breaks down physically the grains, refines them, and is way waaayy quicker than letting your piece cool off and re heat it up from cold. Then he can quench it right away.
And ive tested it myself, ive taken a piece of spring steel, forged it to yellow hot, quenched, broke it, the grain was like sand.
Then i forged it yellow hot, re put it in the fire, only heated it up to cherry red, hammered it for the finishing touches, quenched, broke it and the grain wasn't really visible.
So i'd say it works from what I've experimented, and quenching from orange heat doesn't seem to affect the grain size that much if the normalization was done well before. (i suppose the grains don't have the time to grow too much if you don't let the orange heat soak up too much?)
Hi Jean thanks for sharing your knowledge and experience. Your explanation also does make sense so I appreciate you taking time to share this with all of us!
Never done it more than once per blade myself. Never seen it done three times or even twice. Watched a damned lot of knife making videos here too. Who does it three times?
Subbed, very good info and video!!!!
Hi Dave. Thanks for the comment! I have seen and spoken to a lot of people who did it more than once, again, I think because people thought you'd get the finer grain size by doing so but as Graham explains, you only need to do it once at the right temperature and you'll get the best grain size for your blade then. Cheers!
What is the difference between thermal cycling and normalizing and should you do both?
Hi again Steve! Thermal cycling purely means heating then cooling your blade.
Normalising, as Graham says, is putting your steel back to its “normal state”. I hope that makes sense.
- Vinz
I love the science. There are so many myths about blacksmithing but I studied metallurgy for two years before I built my first forge. Then I snapped things off to see what grain structures looked like. The scientific method wins out every time!
Good content, nice video,and lastly I can hear you plenty now.Thanks👍
Hi Greg! We listened to your feedback and now the video overall is better so thank you for your input previously!
6:58 what is a top temperature ? Thank you ..
The data sheet for a particular steel will give a range that a hardening cycle should be done at e.g. 800-815C for 1080. Graham’s recommendation for normalising is to take the top temperature of that range heat to that temperature +30C. So for the 1080 example the normalising temperature should be 845C (815+30).
[Source: theworldmaterial.com
SAE AISI 1080 Steel Properties Heat Treatment Composition Rockwell Hardness]
This is gonna sound dumb but here goes. Do you have to heat the anvil or hammer when working the steel? Curious if the tool temps were a variable
Hi Thomas thanks for the question. I personally do not see the advantage (or have not witnessed) anyone doing such practice so I am unsure whether this extra process would add any benefit, but I highly doubt it.
Generally it would be a bad idea to heat hammer and anvil up.
Strength generally goes down as temperature increases so if the anvil was hot then it’d be easier to start deforming it. You’d waste energy damaging your tools instead of shaping the work piece.
(I used ‘generally’ a lot since there is pretty much invariably an obscure exception to rules like that. I can’t think of one in this case but I’d not be surprised if one existed)
We learn from our mistakes faster, doing things on our own.
Very true. Thanks for taking time to comment!
This makes soo much more sense, okay. I wish I knew this earlier.
Hi phaledax thanks for taking time to comment! Speak again soon!
Why is there no edge quenching stainless steel?
Obviously it will break, but why?
I would agree that normalising only once makes total sense ( i would roughly define normalising as " dissolving carbides and distributing them evenly, and creating an even structure within the steel" ). i would not of considered the following grain refining cycles as normalising. I would also of thought that with some heavily forged steels that a higher temperature would be needed to properly brake down larger carbides, than would produce an optimum structure for hardening, hence the grain refinement afterwards . i am not disputing what Graham clark is saying ( no way I'm getting into a pissing contest with a dude who's metallurgical micky is way bigger than mine) just saying its interesting to hear this opinion. but either way surely this is all fairly easy to prove through testing. i am just an amateur with limited understanding of the subject so i stand to be corrected on any of the above points.
With refrence to the large carbides. Carbide creation and carbide disolving depend on the diffusion rate of the carbon in the steel. Above the carbide formation temperature, it is more stable for the carbon to be dissolved into the austenite matrix than to remain in carbides. But, the carbon cannot instantly move through the steel so that it is evenly distributed. The speed that the carbon will diffuse through the steel is based on the difference in carbon concentration near the carbides vs the austenite and the temperature of the steel. So, with lager carbides you can spend more time above the carbide formation temperature or go to a higher temperature to speed up the process. As you raise temperature you also increase the rate of grain growth. When we see some unacceptable carbides we will go up in temperature for a short time to fully dissolve everything and redistribute the carbon as best as we can. We would then follow up with another quench from a lower temeprature. I'm heat treated carburized steel parts and not knives, but the metallurgical pricipals remain. Everything in steelmaking is about balance.
For normalizing yeah only once. For some thermal cycling sometimes twice I've heard for some steels 3 times. But that's for really complex stuff and refining them at a specific rate. And for like the last couple percent of "performance" which isn't where you need the performance in the heat treatment.
For heavily worked billets and stuff with lots of cold working. Maybe. Depending on steel.
I think half the time there's issues with people understanding this stuff is the nomenclature being used incorrectly. People get all caught up in these processes that often get labelled incorrectly as normalising, annealing, grain reduction cycles and sort of end up off in the weeds with a whole range of temps (if they're lucky) and not a real solid grasp of what they're doing.
Basically- when in doubt hit up your engineering sheets, then cross-ref if you have to and see if that process is the one you want to achieve
Hi Kris thanks for your input!
Respect to this bloke....no bullshit....just the facts!
Graham is a fountain of knowledge for knife makers. We are very fortunate to have him in our community. Thanks for the comment Wade!
Loooove this information, thank you sir. But can the video editor calm down a bit… it’s cut up like we don’t have an attention span, and some of the B roll just doesn’t seem relevant.
Hi Shaun good morning and thanks for taking time to comment! I appreciate your feedback on the way I’ve cut it but that was done deliberately because believe it or not, most audiences do have a very short attention span but obviously I do take your feedback seriously so I will review my future edits for sure. One question though, have you seen the rest of the other videos we do? What do you think of the edits?
@@UKBladeshow Wow, thanks for taking in my feedback. This video was the first I watched from your channel, what a wealth of information, I’ve since watched several more from you. They’re very well made videos, and I totally understand what you’re doing. I just feel (only speaking for myself) the pace can be a little more relaxed. If you’re watching a video on metallurgy chances are you’re interested in the subject. I realize my first comment might have come across harsh, not my intention. I just felt like his breaths between each sentence were removed and it made it all just to fast for the info to sink in like it would in a normally paced delivery.
Thank you. A new subscriber for sure 🥳
@@shauntheknifeguy hello again Shaun - no need to apologise - I take our audience's feedback seriously! You are right with every feedback you had, but was done on purpose but at the same time, you are also correct - people that would have clicked on the thumbnail/title would have interest in the topic already so perhaps I was overthinking that the audience may lose interest if it was at a normal pace. Thanks again for your input mate! Speak to you again in one of our other videos!
- Vinz
multumesc !
I won't argue with a metallurgist. Awesome advice.
Happy to hear your input! I hope you enjoyed it!
What if the reason for multiple normalizing cycles is not so much the grain size of the steel, but (an attempt at) stress relief? It can be pretty traumatizing to see that blade go ***doioing*** to the side, people get superstitious when they try to avoid a thing that they are not sure how or why happened.
Hi! You might be right that people go mental when their bladder bends like a banana o
@@UKBladeshow a bent bladder sounds painful...
Look for a datasheet/CCT/TTT that has an "Ac1s" which is the highest pearlitic dissolution temp - that'll be the technical name for normalizing non simple steels. Drop it 75°C from that 👍
I normalized in charcoal and the spine is not heated properly only the edge, is that okay
you just invented differencial normalization hehehe
@@hankatmaggies8819 yup but its kinda same, wat do you mean, you need to invent to progress yourself
@@ernestobarrameda1087 Oh, sorry, its a joke, and I expected you to reply accordingly. Looks like your not heating your piece throughout enough. I usually put the spine face down on the flame gust as it has more surface area to heat up than to overheat the edge of the blank. I use charcoal as well and it works perfect everytime. Hope it helps.
Just great fireside chats.
Thanks Marc! We appreciate the feedback!
Silly question... you are talking Celsius?
Hi Sam! Yes we are 🤩
Well how should i soak it in a propane forge?
Turn the heat down. Lower pressure on your propane means less fuel and lower temps. Get a high temp thermocouple and reader (can be had for $50 on Amazon). Controlling the temp on my forge has given me dramatically better heat treatments. You can get a heat treatment that's just as good as using a kiln. Most steel vendors can give you a data sheet that has heat treating protocols on it. Read and follow them.
@@danbance5799 I use a temprature gun to check the blades as i mostly use simple steels like 1075.
@@gundanium3126 You can still turn the forge temp down so it behaves like a kiln. I've tried a temperature gun, and haven't found it to be particularly accurate at high temps, but mine is pretty cheap, yours might be better. Anyway, if your goal is to soak at 1475 or 1500 for 10 minutes or whatever, controlling the forge temp is the way to go. It's much easier to hit your target temp without going substantially over.
What is your take on Heat treating from the annealed state with no normalizing process?
Edit: I had a nice long answer to a question you didn't ask >.<
Yes, you can harden from the annealled state without normalising. However if you've done a lot of stock removale or similar first you could get lots of distortion. A normalising cycle or at least a stress relieve cycle is recommended first.
Also your carbide distribution won’t be ideal if you harden straight from the annealed state. But not ideal might well be good enough for what you want.
The weeds get rather thick if you want to get into them but you’ll mostly be tinkering around the edges optimising the microstructure at the cost of time and energy.
@@GemAppleTom Thankyou for the information Tom. The distribution was what I was wandering about. If I were to forge to shape, fully anneal a blade, clean up the bevels with files, then edge quench heat treat. Would the distribution be the same as. If I would normalize after filling. Also this is on 1095 with a edge quench heating on a coal or charcoal fire. Trying to keep the same color at the edge for up to 1 full minute. I have been doing this for a few decades now. And have gotten good at it. But if I can improve my steel. I am all for it. Thanks again. Tom B. In U.S.A.
@@tombrown879 You might get away with normalising after forging instead of annealing and that should give you better carbide distribution (using the definition of the terms as I understand them) but you might have to remedy more distortion which the annealing would have helped with. If distortion is a big problem then you might have to sacrifice ideal carbide distribution so’s not to make sharp bananas.
Caveat: I’m confident with industrial contract heat treatment and ferrous metallurgy but I don’t have practical experience with blacksmithing or knife making (Ii’s a hobby I’d love to take up at some point). Understanding how things work isn’t the same as being able to do it. If what you’re doing works don’t let me tell you how to do your job.
@@GemAppleTom rarely have any problems with warping doing it this way. And I almost always check for Edge deflection over a brass Rod after tempering and sharpening. It seems to be working okay. But I don't know a lot about the industrial standards just have a lot of trial-and-error through the years. I normally temper at around four hundred and twelve degrees Fahrenheit. This will allow to be able to sharpen reasonably well on a stone and I'm able to whittle on mild steel and still have a good Edge afterwards. Seems to hold up fairly decent but not as good as some other steels I work with such as 52100 or 01.
I think Dr thomas' Knife steel Nerds book wraps the problem well: people tend to get confused between normalisation(performed once and once only) and grain refinement cycles (1 or 2, performed not in descending temperatures but at the right one, that is well below). Both are very different and have their own utility, but to me it boils down to blacksmiths using a treatment that works well but not for the reasons they think. We can save time and effort using science👍
Very interesting. I will have to take a good look at that.
Dr Larin does talk about the grain refining but prefers none, using the Annealing stage to refine the grain. Normalize, anneal, austenize, quench.
Annealing can give more control over the final HRC and toughness, the temp range for tempering isn't huge.
For forging heat treats, using nonmagnetic after normalized/refined helps but you're stuck with max hardness pretty much.@@the_sharp_carpenter
I had to learn the hard way . Color charts data sheets and an inordinate amount of trial and error. I would make a blade ,paying close attention to what I did, then break it to see how flexible it was and to get a look at the grain structure at the break.
Trying to eyeball a thirty degree temperature increase is about impossible. Testing and timing worked , but it’s a long road. Dramatically over grown grain is visibly coarse to the naked eye. Grain that looked like fine flat grey velvet was o k.
The temperature guns weren’t available then. (at least not to me). Temperatures were measured by the melting point of salt, lead, tin, borax, the way water danced on a hot surface or how the surface scorched a piece of wood. After that was fluorescence at working temperatures.
Color charts are great. But color is in the eye of the beholder and it depends on the ambient light in the work area. What works in the shop you normally work in could be off by hundreds of degrees in a work space that is lit differently. Those heat guns are the best thing since tongs were invented.
Thanks so much for sharing the expertise you’ve earned over your life’s experience as a full blown professional metallurgist. 👍
Well said that man!
Cheers 🍻
Ay this guys fucking awesome please keep it up.
Hey dude thanks for taking time to comment!
Thanks for the informative video.. got to admit I've been doing three normalising cycles for years.. never had a problem with the result.. but if I can get away with one I'll definitely save a lot of money on propane 😁🔥all the best Lincoln 👍🤙
Hi Harwood blades! Thanks for sharing your feedback and don’t feel bad that you were doing multiple normalising cycles as many people do, which is why Graham shared his knowledge on this topic and I hope it made sense why!
@@UKBladeshow it made sense and saved money..winner winner chicken dinner..tell Graham thanks for sharing the info.. cheers Lincoln 👍🤙
@@harwoodblades3633 cheers Lincoln! Speak again soon!
I'm loving this
Cheers Kameel!
Pure Gold
Cheers Joan
Normalizing more than once is necessary in industry, but for big parts. But that normalizing is not 3 times the same process of heat it up+ cool it down to room temp, but rather heat it up to +30 from austenitic transisiton temp then cool it down below austenitic maybe -30, then heat it back up to +30 and so on for a few passes then cool down. That is to ensure that your treatment goes into some thick depth of a big plate or round bar above 60mm. For knives, yeah one pass is quite enough.
Not sure I see the point of repeating an identical process even for thick parts…
@@GemAppleTom It is not identical when going in depth. The temperature difference is wavy and such if you try to heat a big a piece to 800 you need to let it soak for hours or risk not affecting the core at all. Also varying the temperature is not felt as well in the middle of a thick piece, as a 60 degree temp difference on the outside might be only a 20 degree diff deeper on the inside. Therefore in it's infinite wisdom the industry added multiple steps (ex. 20-830-770-830-770-830-20) to normalization for THICC parts, checked and tested and found it as much better then 1 pass.
@@dragoscoco2173Cheers for the response.
It sounds like a spec that doesn't understand how thermal conductivity or ferrous metallurgy works...
Pulsing the temperature up and down isn't going to heat the core any quicker. They'd be better getting the core to temperature in a single step - not worrying about the surface being at temp for too long. Then cool below the critical temp and heat again but to a higher temp for a shorter time to get the surface right.
So the process would look like (with added made up numbers)
820C - 180min
Cool to 770C
840C - 30 mins
Cool to RT
Maybe even invest in a time-temperature-austenisation chart...
(My back ground is metallurgy and specifically steel heat treatment. I've seen... how shall I put it... 'less than ideal' solutions in industrial specs before)
@@GemAppleTom I was just giving examples of temp variation, not real world values. But yes that double step would be required in a thicker part to enable a faster cooling of the core (thus normalizing vs, annealing) and afterwards still normalizing the outer shell. Now I am not saying this is the only reason this is done. But cooling rates of big parts by depth comes with a lot of problems of grain size , homogeneity etc. It is rare to use only specs for these operations unless it is some generic steel and generally for specialized parts with complex shapes and welds (cause why not) the thermal cycle is custom made with great inspiration from steel spec, past work but most of all lots of probing and testing.
@@dragoscoco2173 I completely agree that big parts do need a lot more thought put into them. Physics doesn’t care if we’d like everything to heat up at the same time, alas.
A lot of the mad solutions I’ve seen have been caused by people saying “I’ve used this steel and this heat treatment for 40 years! I know what I’m doing!” When the parts are 3 times bigger and under much more stress it’s time to rethink not tinker with an old, familiar process.
I had no idea the magnet was not reliable
Hi Taters. Thanks for the comment. It does work, but not accurate.
@@UKBladeshow Thank you.for.putting out solid information. I.just fired my blade a few hours after your video. We made a forge in the ground with an old 1" pipe, drilled holes in it and put wood and then coal gathered from by the train tracks in there and made several good forgings of rough blades. We used a leaf blower as a bellows and had good success! Now I have the benefit of your knowledge. It's a great service you're doing! Please keep.it.up!
@@tatersdomergue6463 again - really appreciate your feedback thanks!
What about just annealing a blade? Too old to forge nowadays but I used to anneal them in ash that I warmed up with a hot bar of iron first, then put my hot blade in until the next day, sorry to say in the 80s, I’d never heard the word normalize but I’m sure there’s still a bunch of my knives sitting in old mens sock drawers lol. Wish I knew all this info back then
Normalising and annealling are quite similar but have slightly different purposes. Annealling is used to get the steel as soft as possible for later cold working and normalising is there to 'reset' the microstructure. Annealling is done at a slightly higher temperature for a longer time than normalising.
Both need slow cooling and your nice trick with the heated ash (not heard that one before) would do a good job for both.
@@GemAppleTom so the blades I annealed were probably normalized as well? Or at least the grain structure realigned? I learned the annealing from Bill Moran, (still a few of his blades sitting around as well lol)
@@shanek6582 How much detail would you like? There are many, many deep rabbit holes this could go down… I’m a metallurgist who has spent my working life in heat treatment and surface engineering so I can talk about this stuff as empires rise and fall around me.
You can look at annealing as overcooked normalising - if grain refinement is your goal then annealing will give you larger grains (generally a bad thing) and a less than ideal carbide distribution (for the purposes of later hardening and tempering). You could ‘undo’ the annealing by a later normalisation treatment, though.
That’s not to say ‘normalising good, annealing bad’. If you want to remove every last scrap of residual stress and have an ideal carbide distribution for later machining or other cold working then you can consider normalising as undercooked annealing.
But unless you have very specific properties in mind, both will likely do the job just fine. Most industrial specification could be met by either process.
@@shanek6582 I may have missed your question now I reread it…
Normalising and annealing aren’t defined by the cooling speed - both are slow cooled (with annealing sometimes very slowly cooled) but by the time and temperature the piece is held at. Both will cause the piece to transform to austenite when it’s hot and both will transform back it into ferrite/iron carbide when cooled. The main difference is how completely they dissolve carbides and the distribution of them you get when cooled.
Good job bud
I've been telling other smiths about this and getting a bit of flack for it... People get stuck in their ways and refuse to be open to new ideas... Oh well, I'll keep trying to share this gospel truth...
Hi Kevin thanks for the comment! I hope we can help other makers save time by sharing this video! Thanks!
This is gonna save me a lot of propane. Thank you!
Hi Cody! Happy to save you some propane 🥳🥳🥳 hope to see you in our other vids!
Great
Cheers John!
Well that just makes sense..
Cheers Michael!
Maybe a little note from a foreign speaker... I really wanted to follow what Mr Clarke has to say but I had the feeling that you cut away all the natural breathing pauses, wich made it really hard for me to follow. Especially since the topics discussed are rather dense... Great video though, really lets you understand what you are actually doing in the forge! Keep it up!
Hi wild_world, apologies if it was too quick. If I may suggest, you should be able to change the speed of the video to suit your needs if that helps?
You can add the automated subtitles they are not 100% correct but they can help you out a bit.
man i would love to work for u. sad that i live in germany...=D
Maybe one day haha! Thanks ao_analogue
Graham should go on the Joe Rogan podcast lol
That would be fun to see for sure hahaha!
BINGO…
Hey bud thanks for the comment again!
"I'm not going to bore you with the technical details."
NO!!! Bore us. I mean, that's why we are here....🙄
The crap channels tell us nothing. 😥
I've been having this discussion for a long time, everything is in the datasheet, stop trying weird things, there are a lot of research made by the steel makers, and their laboratories, that made a lot of research with a lot of specialized equipment, there are no need for alchemist experiments
Hi Wally! Thanks for your input and I hope you enjoyed the video!
@@UKBladeshow thank you for all the knowledge you share freely!