Cold forging of Knife Steel - Performance Improvement?

[@patricknowak8292]

Cold forging has been around for well over 100 years. I have books of that vintage that describe the process but call it "edge packing" and in that application it was not done at room temperature but at a "black" heat. The principles are the same as what Larrin outlined in his video. The purpose in that application was refined grain and a corresponding increase in toughness. The particular example I"m thinking of was done with a chisel rather than a knife. From an historical perspective, none of the grain refining elements we commonly see in steel were in use back then so the only way to get grain refinement was through the correct balance of forging and subsequent temperature control during heat treatment. The relationship to forging temperature and grain size was documented in 1868 by a Russian named Demitri Tchernoff. His observations were made on cannon forgings rather than hand tools or knives, but the principles are the same. With most modern knife steels, grain size can be easily controlled during heat treatment so the cold forging or edge packing techniques are not adding much value. If you are working with bloomery steel, blister steel or other historical kinds of steels, and a heat treatment cycle that did NOT include a normalize as was common at that time, you would be able to show a more significant relationship between cold work and subsequent grain size.

[@FireCreekForge]

Since this has been something I've messed with a bit, I hope you don't mind if I throw in my two cents: One of the reasons cold forging helps grain refinement is because it mechanically creates dislocations (Dislocations are a normal aspect of steel structure; dislocations are not defects or damage; that's a whole other subject). The benefits of this are only realized upon austenitizing, as Dr. Larrin explained, when new grains are formed. Dislocations are one of several preferential nucleation sites for new grains, and therefore cold forging aids in grain refinement by helping create a higher number of grains. A couple things for those interested in trying cold forging: Traditional Japanese bladesmithing is an interesting study, and seems to be geared towards high efficiency. The processes provide for everything you need in a knife, and nothing you don't. But it's worth pointing out that these methods really don't seem to add anything to the end product other than time efficiency. Everything that is accomplished can be done with other methods, like normalizing and spheroidizing, or some other form of thermocycles. But the speed at which a traditional japanese bladesmithing turns out a high quality blade is impressive. I think it's imperative to point out that traditional Japanese bladesmithing uses very simple steels, such as the White paper steel. It is a high carbon steel, with basically no alloy components. The presence of alloys such as chromium is going to change the picture a bit, as in general this will slow and impede the steels ability to respond to processes like cold forging. Traditional techniques, such as cold forging, typically find application and relevance in materials closest to that which they were developed for. I've tried cold forging 52100, and I don't find it to be very helpful everything considered. I think for the steel to respond it would need a much more extensive annealing process than provided with traditional methods, which kind of defeats the purpose. (on the previous point, old methods come from old materials, and one thing the addition of chromium does for 52100 is help keep the grain size small, which could preclude methods like cold forging.) Aside from the obvious Japanese steels, 125Cr1 or 26C3 are in my opinion better candidates for cold forging. I've used cold forging with 125Cr1, and I've heat treated it without. I don't see a difference other than the interesting appeal of the traditional methods which I mentioned earlier. Another important thing to point out is that in every case I've seen cold forging used in traditional Japanese bladesmithing, it is with san mai or laminate steel, where the high carbon core is clad in low carbon steel. This plays into the process in various ways that I don't fully understand but it does cushion the core steel somewhat; and the total amount of high carbon steel is much less. Lastly, grain refinement in traditional Japanese bladesmithing does not start after forging is completed, but from the beginning. The goal is to forge at the same or successively lower heats as the blade nears the end of the forging operation. When the blade is annealed and then cold forged, it is more completing, instead of fully accomplishing, grain refinement. Thanks Dr. Larrin for another engaging video!

[@sevazinhogamer9521]

Good point, but my guess is when you mix japanese and traditional in the same phrase the result will allways be a harder and difficult way to do something easy.

[@FireCreekForge]

​@@sevazinhogamer9521 I suppose so, a lot of it's a time/effort trade off.

[@markbrown9138]

This is why guys like the aforementioned Murray Carter promote myths about steel, usually to promote white steel, which they claim all kinds of magical things about. I’ve always believed the reason they promote white steel is because it’s easier and cheaper for them, the blacksmiths/makers to work with. It saves them time and money. But they don’t admit that, instead they spread myths claiming that it actually benefits the end user or consumer. Which is obviously nonsense and even contraindicated by Hitachi steels own data sheets. The truth will set you free. I find it hard to believe that a knowledgeable guy like Murray Carter doesn’t actually know better so I have to conclude that they’re lying in self interest.

[@joeyho5134]

Working on projects with your father is super cool, Dr. Larrin Thomas. And thank you so much for sharing your knowledge.

[@S.Vallieres]

Thank you so much Larrin for this another great study and video. Thumbs up!

[@ChateauBeaufort]

Happy Saint Nick's dear Larrin❣️Best of the Season to you & yours. Thank you for these Metallurgical insights... Love your fun input😎

[@JohanLarssonKiruna]

I have no practical use for this information, but I find it very interesting, and I will store it in one of the corners in my brain that deals with metallurgy.

[@JayCWhiteCloud]

04:16 I looked up from working and spit coffee all over my desk...That was wonderful subtle humor...Well done, and thanks for a great informative video that I can now send to folks that tell me "I'm nuts" for working metal cold...

[@njo9966]

Is this the same as “friction forging?” The guys at Knives of Alaska are making some *wild* claims about their D2 steel being “10x better edge retention” than regular D2.

[@KnifeSteelNerds]

Not the same

[@SAKAYA22]

Friction Forge is austenitizing by using high speed friction.

[@KnifeSteelNerds]

I have an article on friction forging already: knifesteelnerds.com/2020/02/03/friction-forged-knives-diamondblade-friction-stir-processing/

[@harrytgough9101]

The 10x claim has to be BS unless by regular they mean annealed 😂

[@LawrenceNelson-t9b]

No doubt all advantages are achieved by higher rc

[@VPLKnifeCo]

I’ve tried this and I have seen (what I thought) improvements in grain refinement at the edge. Easier to sharpen, smaller burr size, etc. The one thing I’ve noticed is a tendency to roll in such a way that I can’t strop it back. I’m not sure if that means lower or higher toughness? But I’ve done it prior to heat and treat and then was very careful not to go above the austenizing temp. Also I did two heat treatments to keep prevent retained austenite. And for this I used 8670, which I think may have been better for this sort of process. Any thoughts?

[@samdahlandsonsforge]

Hey Doc, Is there some science you could ever provide behind the new trend of Carbide tipped hammers? I will be honest I have purchased some Carbide hammers for fixing warps, and I want to keep competitive in producing Damascus without having to throw out a hardened knife. Just wanted to check in with someone on your caliber and I was going to shoot some videos on showing the reactions between hammering on the top of a parabola warp as opposed to the bottom parabola warp. Also I love your content and love the drawback you listed of sleeplessness and divorce, hahaha

[@KnifeSteelNerds]

It’s on the list but it takes time to get to these things

[@samdahlandsonsforge]

@ oh trust me Doc, I understand and can respect that. Thank you for what you do!

[@kevinAuman1]

​@@KnifeSteelNerds Hey Dr Thomas so this is great information on cold rolling/forging but I have always wondered what your opinion was on the company Diamondblade and their "friction-forging" process and the claimed 69 HRC with standard D2 steel yet still claiming no brittleness and easy sharpening? Lol just does not seem to line up with what we know of D2 so me being the curious cat I bought one and let me just tell you as an avid sharpener I am unable to get any kind of an edge more than a simple toothy working edge no matter the technique/sharpening platform used... I've all but surrendered sending it in for a factory edge however I cannot seem to allow it to defeat me so the knife has just sat in a drawer for years now wearing an unimpressive lackluster edge... 😂

[@KnifeSteelNerds]

knifesteelnerds.com/2020/02/03/friction-forged-knives-diamondblade-friction-stir-processing/

[@StephenMcGregor1986]

many military rifles use cold hammer forged (CHF) barrels

[@maseratidyce3587]

Gun barrel steels like 4140 are cold forged cuz they aren’t quench austenitized- they’re never taken up to the point of recrysrallization. Only the inside of a gun barrel needs to be hard. The rest needs to be very tough and dimensionally stable. These steels are work-hardened cuz there’s no other hardening process used in its place. Quenching increases internal stresses, warps the steel, it becomes very brittle. Tempering alone won’t straighten a barrel. Much easier to just thru drill some 4140, hammer forge it around a mandrel, then rifle it or add a rifled sleeve made of something much harder. M240 barrels, for example, have a pure molybdenum sleeve that contains all the rifling. Many other guns and cannons have chromium lining, like Yugoslavian SKS rifles.

[@FluxApex]

Something ive wondered working with firearms. Why do they not use cold hammer forging on knives? We see 2x to 4x the barrel life vs other barrels. I would think this would translate to longer edge retention in knives.

[@F0XD1E]

Could be that toughness isn't as big an issue with barrels since it's not a knife edge and nothing is going to chip the inside of a barrel.

[@jeremymcadam7400]

Barrels generally aren't quench hardened, so work hardening will make a noticeable difference

[@Skinflaps_Meatslapper]

@@jeremymcadam7400 I think this is spot on. They don't necessarily want a hard and brittle barrel, so they don't quench it. The work hardening of a cold forged barrel likely strikes the right balance between hardness and toughness for that application. In addition, the lack of warping and dimensional changes common in quench hardened items would be another reason not to quench, as the cold forging process already brings the barrel to the right dimensions. So in that application, cold forging is the most efficient way to make a quality barrel. Instead of hot forging, quenching, tempering at a really high heat to get rid of most of that brittleness, and then a lot of machining to get where you need to be, you simply take a steel rod and cold forge it to shape and machine whatever bits you can't cold forge.

[@manchagojohnsonmanchago6367]

Because barrels are very very soft. 32 Rockwell or so for a rifle barrel that is cold forged

[@bunker_1284]

Interesting re lower energy required during heat treatment, I have just made a knife out of vtoku 2 with a pretty heavy dimpled finish which was done cold. I found it has some pretty coarse carbide banding following the areas around the dimples where the most dedormed areas are nice and homogeneous! Ive been scratching my head over this phenomenon but it makes sense now!

[@ivanrheeder5158]

Sincerely appreciate the information🙏going to study metallurgy myself and you gave a lot more information then I would ever expect,I would like to ask about the possibility of hardening the edge of a blade by cold forging it in a annealed state,peace be with you ✌️

[@legbreaker5376]

Wanted to know your take I was going to make a rounding hammer out of S7. Would you suggest that or do you think it would work well or better than the average hammer?

[@cledisonrafael4804]

Muito interessante. Não tinha ideia que forjamento a frio estava sendo feito na fabricação de facas. E muito menos que esse processo ainda tem a capacidade de adicionar alguma dureza durante o tratamento térmico. Muito grato pelos experimentos e por compartilhar conosco.

[@nahte123]

Is this comparable to Ed Fowler's process of aus-forging (where he heats below austinitizing, but warm enough to be squishy) from a large diameter for increased percent reduction? He claims to have studies showing 15+ grain size while standard 52100 is around 10...any idea what your samples are?

[@TheBoomsmith]

What about forging hot, but below austenizing temp?

[@accountcontrol]

Ch 11 can be very messy. Any plans to move Magnacut production to another steel mill?

[@KnifeSteelNerds]

www.bladeforums.com/threads/crucible-industries-update.2017101/

[@MaliMeho-v5m]

I frequently forge 80crv2 down to black heat. Tried the same with 52100 and it cracked. Forged another blade from 52100 but made sure not to forge below cherry red and it did not crack. Seems that 52100 needs to be forged very hot? Makes me wonder how does it withstand cold forging without cracking?

[@roberthowell7814]

Not a knife maker, just KNIFE lover, and I had a question after watching this video. Do you think cold rolling could lower production costs for KNIFE makers because it allows them to reach the same hardness at lower temperatures, or did I misunderstand the information. Thank you for your time.

[@KnifeSteelNerds]

The costs of the cold forging or rolling would likely vastly exceed any potential savings from slightly lower temperature.

[@melgross]

It seems as though any improvements are small enough to be within the range of the differences in the alloys sold by different steel manufacturers. People don’t realize how much leeway is allowed in any alloy. Two companies may claim the same alloy, but the composition is sufficiently different that how you work it can result in different results. I don’t make knives, but in my work I’ve found that different suppliers can result in surprisingly different metals. So, I imagine that the testing being done will, to at least some small effect, be dependent on the specifics company’s material. At any rate, I don’t see the amount of differences being of any practical importance. The difference in hardness is minuscule, and while the difference in toughness is somewhat greater, unless you use your knife as a pry bar, it won’t matter either. However, in my area, a single Rockwell point may make the difference between cutting and dulling.

[@krystofmraz]

I Always wondered if manganese steels could be used for knives when work-hardened.

[@SnoPro440]

My high end katana’s that I forge are high manganese steels I have 2 customers in Europe that insist I use the steel for their katana I know the hardness is mid 60s and I get them extremely sharp. They test high 20s on sharpness tester.

[@maseratidyce3587]

@@SnoPro440my understanding of the manganese in manganese steels is that any sulfur impurities that would form iron disulfide instead form manganese disulfide when manganese is present, which causes substantially less structural weakening of the steel’s internal structure. We say it improves toughness and perhaps hardness but only indirectly by bonding with the small amounts of sulfur that are in when the cleanest steel alloys. Manganese steel was the toughest type of steel at the turn of the 19th/20th century and was used for everything from bicycles to the belt armor of dreadnoughts. I’ll be expecting my CruClad 15V on S7XL katana in the mail by the new year. I’ve got holiday plans

[@SnoPro440]

@@maseratidyce3587 my personal katanas I use M390 and for the cutting edge I use tantalum it’s the absolute hardest of all steals and does not break chip or shatter. It’s the most amazing steel known to man And I’m thinking it’s the most expensive too. It’s why I only use it for my cutting edge. Otherwise the katana would cost a half million dollars.😂 you are totally on point about the manganese I’ve been forging Japanese long blades for 30 years now and spent 7 years in Japan spent most of the time learning from the best the secrets of the quench i ended up with a dozen customers that have bought 4 to 7 blades from me and a cpl of those guys are very direct on what types of steels are used I give them what they want when they are paying $5000 to $10,000 for a Katana I have slowly made a name for myself with no advertising, it’s just word-of-mouth from the high-end collectors my most favorite katana I have ever forged I just let go for $20,000

[@MatchGrade08]

I got a steel question T10 is an upgrade to 1095 I know its tougher but am not sure if its edge is harder but its moh hardness seems to be too hard to use with an arkansas stone. Its used often in some swords. It seems to be a tool steel 1095 CRO van is also an upgrade to 1095 and has a few extra elements. I know its used in a few knifes. Which steel is better. Do you think the Tungsten or Chrome Vanadium is the real winner. Knife steel vs Sword steel? Also are there any sword super steels out there (way tougher than most steels but keeping its edge). Would t10 be close to a sword super steel?

[@mike-carrigan]

So if I don't have a power hammer but I do have a hydraulic forge press, could I still press the material? Would it be like cold rolling?

[@KnifeSteelNerds]

It would be a form of cold work, yes.

[@verdigrissirgidrev4152]

5:53 I'm not sure calling a 50% (!) to 25% improvement in the 58-62 HRC range 'very small' is warranted. but this study is probably worthless since they didn't control for grain size re 12:02. 6:38 / 10:06 so cold working could potentially allow for lower aust temp, at least in low alloy hypereutectoid steels w short holding temp? 7:55 what about CW+cryo? 13:30 why use 5160 instead of 52100?

[@KnifeSteelNerds]

I showed 5160 because it shows more the effect of grain size alone, which was my point about underaustenitizing for grain refinement. The 52100 data is affected by extra carbide where the lower austenitizing temperatures show lower toughness.

[@NMiller_]

Do you think that given historical materials and methods of forging there was any advantage to cold forging, and that perhaps our technology and techniques provide better results now? Curious if you think this could have ever been game changer, or was just another case "it works for us so we keep doing it" ?

[@KnifeSteelNerds]

Probably they did it for other reasons like controlling the final shape and removing scale.

[@me2bfc]

Might be left over from when copper and bronze were hammer hardened

[@maseratidyce3587]

@@me2bfcthinking a bit too far back. We were aware gradual cold rolling at elevated, up to cherry red and down to room temp, produced tougher steels for armor in ww2

[@me2bfc]

@@maseratidyce3587 industrially yes, that is probably true. However, knife makers will find some notes scribbled on a napkin outside a blacksmith shop preserved in Pompey and they’ll try it and swear it works better than anything ever.

[@edisonfrisbee6345]

Does anyone recall the name of a knifemaker from the ~60s who supposedly had a secret cold forging process that he took to the grave?

[@aHippieWithKnives]

awesome

[@nairolf8144]

I may sound like an idiot but wasnt the claim that the edge retention was better when cold forged at the last stage on the edge ? Not that I have an opinion either way, but as an armchair specialist, I feel like the tests didnt really answer that specific claim?

[@KnifeSteelNerds]

The claims I was addressing were grain refinement which leads to potential toughness improvement. I’m sure someone out there would claim improved edge retention but grain refinement doesn’t do that unless doing a cutting test that leads to chipping where toughness would help. If the edge retention improvement was just from the slight increase in hardness you could achieve that in other ways like tempering. I tested where potential improvement could be seen.

[@nairolf8144]

@@KnifeSteelNerds I see, thank you for your answer, for some reason i felt like the claim was that the "flattened scales" pattern of the grain on the edge after hammering would slow the rate of shredding of the final edge somehow. Again, thank you for answering !

[@KnifeSteelNerds]

The flattened grains would go away after it is austenitized. I wouldn’t recommend cold forging the hardened steel. Or skipping the heat treating. I wouldn’t anticipate flattened grains to benefit edge retention either way.

[@nairolf8144]

@@KnifeSteelNerds Oh yeah, the posts I saw were about cold forging the edge after the quench and the temper, which did seem very risky. And good to hear you wouldnt expect an improvement, one less thing to mess with for me ! Thank you Larrin.

[@filepz629]

❤️‍🔥

[@importantname]

Sounds like in short: cold forge is different to hot forge. Both minor improvements and reductions. But nothing significant to claim it is much better ?

[@tylerh6054]

If cold forging can cause divorce im headed out to the shop RIGHT NOW!!!! 😂🎉😂🎉😂🎉

[@ThisIsToolman]

Cold rolled stock is only cold formed near the surface. Also, trash is crushed into the surface with the cold rolling.

[@kurtbilinski1723]

"... positive studies tend to get published more than negative studies..." Separating human nature from facts is one of humans' biggest challenges!

[@rogervogel5075]

Frank Richtig supposedly did this

[@KnifeSteelNerds]

Richtig didn’t forge at all

[@rogervogel5075]

@KnifeSteelNerds clarksonhistory.wordpress.com/2013/05/06/secrets-of-the-dead-the-richtig-knife/

[@rogervogel5075]

@KnifeSteelNerds he sure did forge because he was a blacksmith but his knives weren't forged he used stock removal and he supposedly austemperd his knives his knives where famous for being able to do what they did years before austempering was invented by metalurgists

[@rogervogel5075]

@KnifeSteelNerds clarksonhistory.wordpress.com/2013/05/06/secrets-of-the-dead-the-richtig-knife/

[@songman0]

This is a way how a scythe be good to cuta grasss.

[@jasonscott7803]

👍✌️⚒️

[@pistole2004]

And i though that Cold forging is only for by passing the damage reduction of Fey.

[@candyshop84106]

Juat a FYI to Larrin Thomas, I also am a Thomas.😁... I have been on a quest to push away all the B.S. of some sword makers, looking for truth. Have learned a lot, from many different sources. AT THE END OF THE RAINBOW, IS LARRIN THOMAS. There is Noone that can lie or spin things past Lorrin. I am similar that way and can male people angry even though they were wrong. (Humans amd Theor Fragile Egos) LORRIN IS AWESOME. Lorrin is whats So great about internet. Knowledge at ones fingers..With that, the most money made is Porn.😃.. 😊

[@markbrown9138]

Alrighty then. Thank you for that.

[@monkey6430]

A classically trained japanese bladesmith - born in canada🤣

[@alextopfer1068]

It's almost like people can travel and study overseas

[@shaolinfox30]

Your ignorance is massive! Murray Carter is a world renowned Bladesmith. he absolutely did study in Japan for years. As a matter of fact, he trained and had a shop in Japan for over 18 years, smart a$$