How To Heat treat again?

[Larrin]

Thank you, Larrin. I will change my heating advice from now on. I edited the previous posts.

Any thoughts on forge HT for higher carbon steels like 1095, W2, Hitachi White/Blue, 26C3, etc.

The forge heat treating article I previously posted has results for forge heat treatments I performed with 1095, O1, and 52100.

 

[Stacy E. Apelt - Bladesmith]

Thanks, I'll go back and read it.

 

[Natlek]

Many famous Japanese Knifemakers use coal forge to HT their knives .Lot of them are big kitchen knives ? It's hard for me to believe that they don't know what they're doing . . . . .

 

[Way-Barney]

Many famous Japanese Knifemakers use coal forge to HT their knives .Lot of them are big kitchen knives ? It's hard for me to believe that they don't know what they're doing . . . . .

It's interesting to consider the reasons why the Japanese sword makers felt the necessity to introduce clay to their swords, perhaps they quickly identified an inadequacy in the finished product (possible overheating of the steel?) and then came up with a solution, claying the back to soften the sword thus alleviating the inherent problems due to lack of temperature control, the term I use in these scenarios are manufacturing solutions to engineering problems.

If I had no option other than HT in forge, I think I would clay everything.

 

[DevinT]

There are a lot of poorly heat treated Japanese knives.

Hoss

 

[DanF]

There’s a difference in knowing what you are doing and HT’ing with the best,most accurate method. I love going “old school” and heating and beating and doing the heat treat as I was taught over 25 yrs ago, but, I accept that a kiln is better at temp control than the human eye. A forge is a good/great place to start if that’s what you have and aren’t ready to go all-in with this knifemaking thing.

 

[Stacy E. Apelt - Bladesmith]

I will add some history to Dan's comments:

What is a "Poor HT" to a modern metallurgist was perhaps the "Best HT in the world" up until around 60 years ago.
Until modern SEM machines, metallurgical scopes, and modern testing equipment allowed structures to be easily examined, there was no way to know what the internal structure was to the degree that Larrin and others have today. Temperature control and measurements were not the same as today. I'd bet that in 1950, 25° plus or minus was considered a very close measurement at 1500°.

HT was done by eye in a simple charcoal forge for several thousand years.
High-tech became a Johnson natural gas forge around 120 years ago.
Watson created the Evenheat electric kiln around 1950.
Knifemaking kilns came out around the 1970's, maybe later.

Charpy created his testing machine around 1900. Rockwell came along 20 years later. Both of those tests were not available to anyone but a lab.
The Curie point was discovered around 1900. I doubt it was used for knifemaking until quite recently.
The "advanced" studies on Troosite (now an obsolete term) were only about 20 years old when I was born. In 1930 they couldn't image the actual structure optically.
Today a hobbyist can get a Rockwell tester ... if you can afford one ... but advanced tests like Charpy and structural micrography are still for labs.

There were no programmable HT ovens when I was learning to forge.
There was no hobby level equipment at all. It was a used farriers forge, an industrial gas forge the size of a washing machine, or something you built at home from old auto parts and junk.
I don't recall anyone with a belt grinder as a lad - just grinding wheels, files, and stones.
There were no knifemaking books or metallurgical references like Larrin and Verhoeven have produced. (Yeah, for those guys!)
Knife Steel was what you found in the junk pile or behind the barn on old equipment. There was no readily available steel supply for knifemaking. You had no idea what the carbon content was beyond anecdotal references like "all car springs are 5160, all files are W2, etc..
Knifemaking supply companies did not exist at all.
When I was 20, I bet there were not 1000 hobby knifemakers in America. The "famous makers", Like Moran and Sagel had no training or technical skills, and no modern equipment. They just did what worked to make a knife. I am sure the knives would be considered "poor" by today's standards.

Most equipment now considered necessary to make a knife, like belt grinders, HT ovens, commercial quench oils, and machine shop tools ... and known steel ... were beyond the reach of me for 40 years. They are still not affordable for most hobby makers.

Today, in less than 10 seconds I can look up those dates above and find the transformation diagram of any steel I want. I can also read Larrin's articles and reports on Knife Steel Nerds the day after he writes them.
The ASM HTer's Guide is several hundred dollars. Verhoeven's Steel Metallurgy and Landes' Messerklingen und Stahl are about the same. Other texts can run up to over $1000. Larrin's book is $50, and you can read most of it for free online. He answers questions and posts links to his articles and testing for us here in Shop Talk. I am positive I could never have had any access to ask a question to Verhoeven and others. We are so blessed by Larrin and his friends.

The point is that the world of knifemaking is expanding rapidly due largely to modern internet communications and technology. It is becoming what I call "Metallurgical Knifemaking". This is a good thing.
But, as with any fast change it takes much longer for those changes to disseminate down to those who have been doing it "the old way". What has worked well for a long time is still quite acceptable to many of us. It is also fine with most of our customers, too.

 

[aareeyesee]

I will add some history to Dan's comments:

What is a "Poor HT" to a modern metallurgist was perhaps the "Best HT in the world" up until around 60 years ago.
Until modern SEM machines, metallurgical scopes, and modern testing equipment allowed structures to be easily examined, there was no way to know what the internal structure was to the degree that Larrin and others have today. Temperature control and measurements were not the same as today. I'd bet that in 1950, 25° plus or minus was considered a very close measurement at 1500°.

HT was done by eye in a simple charcoal forge for several thousand years.
High-tech became a Johnson natural gas forge around 120 years ago.
Watson created the Evenheat electric kiln around 1950.
Knifemaking kilns came out around the 1970's, maybe later.

Charpy created his testing machine around 1900. Rockwell came along 20 years later. Both of those tests were not available to anyone but a lab.
The Curie point was discovered around 1900. I doubt it was used for knifemaking until quite recently.
The "advanced" studies on Troosite (now an obsolete term) were only about 20 years old when I was born. In 1930 they couldn't image the actual structure optically.
Today a hobbyist can get a Rockwell tester ... if you can afford one ... but advanced tests like Charpy and structural micrography are still for labs.

There were no programmable HT ovens when I was learning to forge.
There was no hobby level equipment at all. It was a used farriers forge, an industrial gas forge the size of a washing machine, or something you built at home from old auto parts and junk.
I don't recall anyone with a belt grinder as a lad - just grinding wheels, files, and stones.
There were no knifemaking books or metallurgical references like Larrin and Verhoeven have produced. (Yeah, for those guys!)
Knife Steel was what you found in the junk pile or behind the barn on old equipment. There was no readily available steel supply for knifemaking. You had no idea what the carbon content was beyond anecdotal references like "all car springs are 5160, all files are W2, etc..
Knifemaking supply companies did not exist at all.
When I was 20, I bet there were not 1000 hobby knifemakers in America. The "famous makers", Like Moran and Sagel had no training or technical skills, and no modern equipment. They just did what worked to make a knife. I am sure the knives would be considered "poor" by today's standards.

Most equipment now considered necessary to make a knife, like belt grinders, HT ovens, commercial quench oils, and machine shop tools ... and known steel ... were beyond the reach of me for 40 years. They are still not affordable for most hobby makers.

Today, in less than 10 seconds I can look up those dates above and find the transformation diagram of any steel I want. I can also read Larrin's articles and reports on Knife Steel Nerds the day after he writes them.
The ASM HTer's Guide is several hundred dollars. Verhoeven's Steel Metallurgy and Landes' Messerklingen und Stahl are about the same. Other texts can run up to over $1000. Larrin's book is $50, and you can read most of it for free online. He answers questions and posts links to his articles and testing for us here in Shop Talk. I am positive I could never have had any access to ask a question to Verhoeven and others. We are so blessed by Larrin and his friends.

The point is that the world of knifemaking is expanding rapidly due largely to modern internet communications and technology. It is becoming what I call "Metallurgical Knifemaking". This is a good thing.
But, as with any fast change it takes much longer for those changes to disseminate down to those who have been doing it "the old way". What has worked well for a long time is still quite acceptable to many of us. It is also fine with most of our customers, too.

I would like to thank everyone in this thread for posting such valuable and interesting information. There are a lot of badass knife makers, and incredibly intelligent people on this forum. Having just started messing with knives in August I read every post whether or not I think it applies to me because of posts like the one above or when there may be a Hoss or Larrin sighting dropping all sorts of knowledge.

Seriously, Thanks to all of you that spend time helping dummies like me.