Triple Quench 0-1?

Phillip, much of "control of carbide size" starts when the steel is made .Compare for example, 154CM and CPM154 .154CM is conventionally made with larger carbides ,and CPM154 made with the CPM method with smaller more uniformly distributed carbides. In the higher carbon steels you never dissolve all the carbide originally there. You may move it around and create serious problems [continuous grain boundary carbide] but it's still there. Proper HT dissolves carbides until the matrix is saturated with carbon .That matrix is turned to martensite and on tempering produces very fine carbides .Some of those carbides will have coherency with the matrix for even more strength and the carbides give wear resistance too. Those are the "many very tiny little chromium carbides"
 
mete said:
Phillip, much of "control of carbide size" starts when the steel is made .Compare for example, 154CM and CPM154 .154CM is conventionally made with larger carbides ,and CPM154 made with the CPM method with smaller more uniformly distributed carbides. In the higher carbon steels you never dissolve all the carbide originally there. You may move it around and create serious problems [continuous grain boundary carbide] but it's still there. Proper HT dissolves carbides until the matrix is saturated with carbon .That matrix is turned to martensite and on tempering produces very fine carbides .Some of those carbides will have coherency with the matrix for even more strength and the carbides give wear resistance too. Those are the "many very tiny little chromium carbides"
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Ah, that makes sense. Thanks for finally answering my question. :D
 
This seems like a good place to ask about triple tempering for steels such as 1095, O1, and such. Many knifemakers recommend multiple tempering cycles, 3 cycles for 2 hours or something similar. For the simpler steels, only single tempers are recommended in the literature I've read, Verhoevens book, Smiths Engineering Alloys, some manufacturer's data, and an occasional trip through ASM's Metals Handbook. The times given are also shorter, typically 1hour, unless the piece is to be EDM machined, in which case 4-6 hours is typically recommended. Is one hour enough, or are the multiple cycles needed?
 
01 does need more soak time than simple steels. However, you can do a good job on 01 with a simple solid fuel set up. I've been using a muffle furnace for about ten years now. It's basically a thick walled steel pipe that is suspended over the coals. It's capped on the back end and has a ceramic thermal blanket over the top. I put a wooden splint or fuse in the back to create a reducing atmosphere inside. The pipe soaks and muffles the heat evenly. It's also fairly easy to see into.

You can use the same idea inside an electric furnace. I used a controlled electric furnace for about ten years before I switched over to solid fuels. You can put some wood chips or charcoal directly into the chamber to help control the atmosphere, but setting up a muffle inside the furnace for a contained reduction atmosphere works even better. You can cap the back end and put a loose fitting plug in the front, and pull it out when you are ready to quench. This way you don't have to worry about scale and decarb.

The muffle concept can also be adapted to gas forges.
 
Simple steel -- simple temper. Plain carbon steels a single temper for one hour is fine. For a S30V I'd do a 2+2+2 temper.......EDM - make sure you ALWAYS temper after EDM [not before] !! I spent a lot of time in the early days of EDM explaining why their EDM dies cracked ! EDM vaporizes steel and the remaining surface has been heated high enough to produce Austenite and untempered martensite !!
 
mete said:
Simple steel -- simple temper. Plain carbon steels a single temper for one hour is fine. For a S30V I'd do a 2+2+2 temper.......EDM - make sure you ALWAYS temper after EDM [not before] !! I spent a lot of time in the early days of EDM explaining why their EDM dies cracked ! EDM vaporizes steel and the remaining surface has been heated high enough to produce Austenite and untempered martensite !!
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Dies and knife blades are two different specializations.

I think it's true that multiple tempering will make the alloy steels tougher, but based strictly on my experience, it also makes the edge a bit harder to sharpen to a high degree and makes it less aggressive in terms of cutting. There's always those kinds of trade offs to consider.

"For every action there is an equal and opposite reaction."

It's like Kevin suggested, performance is subjective,... and shouldn't always be reduced down to black or white. It just depends on what your preferences are and what you are after in the finished product.

Metallurgy can be helpful if it is kept in it's proper perspective.
 
Chris Meyer said:
For those of you with the time and interest, John D. Veerhoeven PhD has written, and generously posted (in .pdf format) for free, a book entitled Metallurgy of Steel for Bladesmiths & Others who Heat Treat and Forge Steel. I am in the process of reading this book, which is written for Bladesmiths and Blacksmiths, and it's quite fascinating. I strongly recommend it to everyone in the forums.
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Anyone know if this PDF is still available online somewhere? i just tried to look at it, and the file no longer exists on that server :(

Thanks,
-Page
 
sunshadow said:
Anyone know if this PDF is still available online somewhere? i just tried to look at it, and the file no longer exists on that server :(

Thanks,
-Page
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It is now under copyright and available for purchase through ASM. There is at least one place on the internet that still has the free version, but I don't know if posting a link to that would be proper now that it is copyrighted.
 
Maybe the question should be, "what properties should any given knife blade or tool have,... hardness, toughness etc...?"

For sure, it should have the properties to do what it was intended to do, and then some,… just for good measure. After that, who knows?

We have knives and dies going, lets throw in files. Files are also cutting tools, commonly made from fairly simple high carbon steels with minimal tempering, or no tempering at all, except on the tangs. Most of them are not even normalized before hardening, and the entire thermal processing is very minimal. However, I have never had a file fracture or break on me during normal or even extremely hard use.
 
Mete, I haven't had the funds to upgrade to paid member status, hopefully I'll be able to upgrade sometime in the next couple weeks, but right now I can't do PMs


Thanks,
-Page
 
sunshadow said:
Anyone know if this PDF is still available online somewhere? i just tried to look at it, and the file no longer exists on that server :(

Thanks,
-Page
Click to expand...

I just googled it and the first result was a link from which I was able to download it, no problem :o
 
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