Heat Treating - Can someone help me understand what Murray Carter is doing?

HSC /// said:
Stezann, the process annealing (slow cooling annealing) that Murray uses does work,
I use it myself on all laminated steels. I'm not aware of what harm it does,

spheroidize heat treat has its place but I would say it's not required with the high carbon laminated steels

regards
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The steel will be soft, but softness it's not the whole story.
If you take a full solution and cool it giving it enough time (slow cooling in ashes and the like) the proeutectoid carbon will have the time to precipitate at the grain boundaries, creating a brittle frame encasing the matrix...Chances are that if you don't have the right equipment to provide a real good soak, you won't dissolve all this cementite and will have leftovers at the grain boundaries in the final austenitization. There's more to slow cooling hypereutectoids: when all the proeutectoid carbon has precipitated you start forming coarse pearlite inside the grains. The thick cementite plates of the coarse pearlite will dull your drill bits faster than the spheroidal cementite and it will require a lot of time to be soaked to be put back in solution for the final hardening.
Air cooling, followed by subcritical cycling provides a better steel to drill and a better situation from which hardening in the end of the day (it could be the same day too!), it will go back in solution very quickly, since they will not be big spheroids.
I hope i used the right words to explain it and to be of help.
 
You can create large or small spheres , and fine or coarse pearlite . The soak is to dissolve and diffuse carbon to get maximum strength of the matrix.

Stefano , you've been learning more and more !!
 
I think HSC was talking about slow cooling in ash from a sub-critical temperature.
 
Rick Marchand said:
I think HSC was talking about slow cooling in ash from a sub-critical temperature.
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Exactly. Thanks for pointing this out Rick. I had written a whole reply about why it's a bad idea to slow cool hypereutectoids,......from critical or above. Almost word for word with Stefano. When I realized that the anneal being discussed here was from a SUB critical temp, I deleted my comment. Regardless, if you want to anneal a hypereutectoid, the "best" way to do this is by spheroidization. A lamellar anneal will grind OK, but not drill/file as well as spheroidized cementite. Lamellar anneals are like a bunch of layers, some soft, some hard. Those "hard" "layers" are hell on CNC tooling/drill bits. A spheroidized structure is much much easier on tooling.
 
In the past, I have jokingly said that it is a testament to the skill of the traditional Japanese smith that he can produce such fine blades in SPITE of the techniques that he uses. Am I the only one who cringes when they see a smith "cold forging" a blade? :eek:iMr. Carter and other Japanese and Japanese trained smiths do what they do because that is the way that it has been done in Japan for centuries. And if you are good enough, it works quite well. But think about this. Where else in the world is ANY forged welded blade considered to not only be inferior, but easier to make than a monosteel blade? ;)
 
Jdm61... I cringe as well and used to be more vocal about it. I'm tytpically a black and white type of guy... this is right, this is wrong. The more I learn about metallurgy, the more I realize how little I know. I believe there is a place for most techniques developed by bladesmiths throughout the ages... especially ones that have stood the test of time. Maybe not the entire method, but certain aspects. I can't help but think that if "controlled" cold forging didn't impart something to the steel, it would not be used, today.

That is not to say that cold forging is doing anything magical or not achievable by other means. It could be as simple as creating dislocations where new nucleation points can form upon recrystalization. Or perhaps, because Mr. Carter is mostly using a high carbon core wrapped in a low carbon jacket, that the cold forging is actually intended for the mild steel(which would be more forgiving.) This would be useful in tuning(straightening) and stiffening the blade, post-heat treat. I see where there is potential. It is just another way, not the only way.
 
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I have a good friend who is an old school bladesmith..He heat treats 52100 in a forge and uses some of 'those" methods for it but not all of them. Kind of a hybrid between old and new. He quenches in the transformer oil that goes in electrical transformers..Hes done the same thing, the same way for years with the same steel. He can make his knives within a measured RC point of were he wants them every time heat treating in a coal forge. they all come out 59-60rc..he hollow grinds freehand on an old wilton square wheel(running wide open at about ten million rpms) down to a super thin edge that flexs like a razor blade but that's the way he wants them and that's the way the deer hunters like them..
His way is certainly not my way but Id be amiss if I didn't give the credit he deserves. He makes a damn fine knife that anyone would feel good to use.
 
Not related to the HT specifically, but I wonder how he just drops those two hot bars to heat the water in what seems to be a plastic 5 gallon bucket without burning through it.
 
Tenebr0s said:
HSC, I'm curious to hear your experience; around what temperature would you say Murray annealed his blades at? (I know the manufacturer specs for shirogami steel say 740-770 C for annealing, but it's not clear to me whether they are actually recommending a rice ash anneal at these temps). Would you say the blades were sub-critical when going into the ashes or was the temp similar to what he quenches at?

I believe a sub-critical rice ash anneal would be fine for hypereutectoids, since this isn't going to lead to carbide precipitating in the grain boundaries.
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look at 10:20 https://www.youtube.com/watch?v=HrasEQhVOLo
 
Thanks again Rick ;) I didn't get the rice ashes were used at subcritical...that's spheroidizing!! Slow cooling from subcritical you get bigger spheroids and softer steel than through just cycling at subcritical.

The cold forging reminds me of the method of correcting the bends/kinks and tensioning the teeth of the hand saws. Aside very brittle structures, tempered steel (possibly at tempering heat) can take a bit of it without much harm if it is necessary.
 
Cold forging is useful for a lot of things. It's done here in Japan to straighten blades, smooth the texture of the knife after forging, and even for forming the hollow (urasuki) on the back of single-bevel knives. There is also the claim that it can lead to grain refinement (I'm not saying this is the best way to do this). On laminated knives, using very pure steel, it doesn't appear to have a negative impact.

People are often quick to write off Japanese techniques as just the blind-following of tradition, or to argue that it's all just hype. I do take everything I learn here with a grain of salt. I study metallurgy the best I can and use a digitally-controlled kiln in my heat-treating. But Japanese knives are not all hype by any means. Hype might sell knives to weekend warrior pocket knife fanboys, but it's not going to get you very far in the world of chef knives, where Japanese cutlery excels. Chefs would have little patience with anything that didn't perform very well. Just my $.02
 
Most of what you say I more or less agree with ( when applied to laminated blades). The grain refinement issue of cold forging is a myth, though. In many other metals, deformation induces nucleation and grain refinement will be possible .... but not on high carbon steel. The chance of grain separation ( shearing along grain boundaries) is much more likely, which would be very bad.

As far as Japanese chefs preferring a Japanese blade over others being proof of the Japanese blade's superiority, I was under the impression that there were rather strict laws about importing most any Japanese style knife into Japan. I have had Japanese collectors tell me that they could not buy a Japanese sword of mine because they could not take it to japan. I have hear that this was also true of Japanese kitchen cutlery. On fellow put it in simple terms - "You can send me a Bowie knife, because we don't make bowie knives. You can't send me a wakizashi, because we make wakizashi, and want to protect the guild."
Is this still the rules?

In the US and Europe, I believe many Japanese chefs are quite happy with knives made by non-Japanese makers. I personally have supplied blades to the chefs at Japanese restaurants who say mine are equal to or better than what they bought from Japan ( for much higher prices).


Since you are a Japanese maker, and may have insight into the steel trade in Japan, can you give an explanation of why the purest grades of white paper steels can not be shipped to the USA? ( with very rare exception like Murray Carter).
Many of us have tried repeatedly, and been either ignored or told it was not allowed. A group of us tried to but $20,000 ( ¥2,076,450) worth of Hitachi #1 white paper steel a while back and were still refused.
 
Stacy E. Apelt - Bladesmith said:
Since you are a Japanese maker, and may have insight into the steel trade in Japan, can you give an explanation of why the purest grades of white paper steels can not be shipped to the USA? ( with very rare exception like Murray Carter).
Many of us have tried repeatedly, and been either ignored or told it was not allowed. A group of us tried to but $20,000 ( ¥2,076,450) worth of Hitachi #1 white paper steel a while back and were still refused.
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I can't answer from a Japanese perspective, but I can try to infer some insight.
As a student of Murray's, I can buy his steel. In fact he just rec'd a large shipment.
Carter indicated in his recent newsletter that he's given his commitment to only release the steel to graduates.
Because graduates have learned the Japanese bladesmithing techniques he teaches for this Hitachi laminated steel.
These techniques bring out the best performance in the steel. So it's a control issue and making sure the value of the Hitachi steel name is upheld.

O1 or W2 in the hands of a novice knifemaker may not perform the same as that from an accomplished knifemaker who has worked hard to perfect that steel's capabilities.
Thus the same would hold true for Hitachi steel. The Japanese seek to make sure that sub-standard blades made from the hands of an "untrained" bladesmith don't damage the reputation of the Hitachi product. It dilutes the value of the product.

A specific case in point. A newer maker recently contacted me because his laminated steel was splitting right down the middle at quench.
After discussion I advised him to stick to the procedure and steps I outlined in my HT sticky. He was doing a different anneal and some other cycling that is not part of the known and proven process. Laminated steel splitting down the middle is an extreme case of course.

Even recently I gifted a test blade and it turns out that I might have blown out the grain due to overheating. Or it was too hard, I don't know yet.
This is my first blade failure that got released.

I'm a personal fan of this steel for several reasons.
1) stainless cladding with a high carbon core is the best overall compromise for a steel in my opinion
2) it's "simple" to HT myself, which saves me time and money.
3) I like high carbon edges, gets very sharp and easy to sharpen. User customers love the edge and they buy again.
 
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Stacy E. Apelt - Bladesmith said:
As far as Japanese chefs preferring a Japanese blade over others being proof of the Japanese blade's superiority, I was under the impression that there were rather strict laws about importing most any Japanese style knife into Japan. I have had Japanese collectors tell me that they could not buy a Japanese sword of mine because they could not take it to japan. I have hear that this was also true of Japanese kitchen cutlery. On fellow put it in simple terms - "You can send me a Bowie knife, because we don't make bowie knives. You can't send me a wakizashi, because we make wakizashi, and want to protect the guild."
Is this still the rules?

In the US and Europe, I believe many Japanese chefs are quite happy with knives made by non-Japanese makers. I personally have supplied blades to the chefs at Japanese restaurants who say mine are equal to or better than what they bought from Japan ( for much higher prices).　
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I didn't mean to imply that Japanese knives were superior in any way to well-made American ones. My point was just that Japanese knives are extremely popular with US and European chefs, and if Japanese production methods produced inferior blades, chefs would notice. I sometimes feel like people are quick to explain away the popularity of Japanese knives to hype, but I don't think hype would last very long in the professional kitchen, where performance is everything. That doesn't mean that knives by American makers can't perform as well or better.

As for the shipping of Hitachi steel, the knife making scene here tends to be insular and guild-like. Hitachi sells steel to groups of knife makers who form cooperatives in order to do group buys. I don't know why Hitachi doesn't sell directly overseas. Perhaps they are trying to protect the knife making industry here, I'm not sure.

EDIT: just to clarify, I'm not Japanese. I'm from the USA, but have lived in Kyoto for about 7 years now : )
 
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I am a new maker (about to order my first 2x72!!) and I use 52100 because I like carbon edges.
Now for my point, as a career I am a sous chef at a fine dining restaurant in America. I primarily use Japanese knives with my favorite at the time being those made by Yu Kurosaki and Gihei knives, they tend to use Aogami Super steel, Blue #2, and some exotics like R2/super gold 2 and HAP40. I believe all of those steels are Hitachi. I love White steel edges, they are almost "sticky" when I take them off the stones, they want to grab onto and cut everything. White steel gives me the best feeling edge and I prefer it on all my knives that make very little cutting board contact(yanagi/honesuki/sujihiki). Now the AS and Blue steel edges feel almost the same, they can take the same degree of refinement. After a strop on a 6k stone and a 1 micron loaded balsa strop my Gihei blue#2 knife will cut free hanging hairs all day and hold the edge while I chop an 8 hour prep shift away. I like these for my gyutos.
That said, I've used American steels that take amazing edges and are heat treated amazingly and are just awesome. I use japanese knives because of the grinds primarily, I have only used kitchen knives from a few local makers here but all their knives are just flat ground. All the japanese knives I use are flat ground on the left side with a slight convex on the right and this subtle difference makes them out perform any American knives that I have used. I am working to become a knife maker because I want to make good performing knives with nice grinds that are affordable for the low paid line dogs that I've watched work their behinds off for years. When choosing knives now I do not look at the steel as much as I used too, I look at the grind. Steel comes second.
Also I'm only comparing the USA made knives that I have used from local makers, not saying all USA/European blades are just plain flat ground. As a matter of fact I know many of you convex some or do S grinds I just have not had a chance to use them.
 
comet_sharp said:
they tend to use Aogami Super steel, Blue #2, and some exotics like R2/super gold 2 and HAP40. I believe all of those steels are Hitachi.
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The Hitachi steels aren't magic: Aogami ("Blue") Super is Hitachi's version of AISI O7 tool steel. Hitachi White #1 is unique in that it's very clean plain carbon steel with 1.3% carbon, but White #3 is essentially identical to very clean 1095.
 
"These techniques bring out the best performance in the steel. So it's a control issue and making sure the value of the Hitachi steel name is upheld."

Not at all directed at you, Harbeer, please don't misunderstand my mini rant here....not aimed at you. I also receive the MC newsletter email. I was slightly miffed when I saw the new batch of Shiro he got, and the statement that Hitachi will only sell their steel to Japanese smiths because they don't want the HT done improperly by someone else, and then giving the steel a bad name.

What CRAP. Does this not rub anyone else raw? AFAIK, no other steel company holds to this ridiculous policy. First of all, a few techniques the Japanese smiths do to their steels are questionable at best. And does Hitachi really believe that only the minimal temp forging, edge packing, wood ash anneal, HT in a coal forge, water quench, single minimal temper is the way to do it???? I say "screw em". It's not like Shiro and Ao steels are superior to others anyway. Just a mystique that is trying to be built around them.
 
Lots of common steels are better than white or blue steel. These alloys are made for easy heat treating. They are adequate for most cutlery applications, but not superior. I don't understand all the hype.

Hoss
 
...ecc...

From the video, aust & temper temperatures judged by MC's eyes must be varying within acceptable range. Otherwise, outcome would be poor, right? Aust temp & very-short soak are critical. It could be (my wild guess) how steel was annealed+cold-hammered along with clean material (um... I take what being marketed & repeated by others)... well temperature & steel attributes can easily be tested BUT it's more fun to guess ...
 
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