CPM D2 heat treat

R

rincan

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Aug 20, 2014
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I am wondering if anyone has some information about heat treating CPM D2. How is it done best? Also ive heard talk of freezing the blade or cryo treatment, is this beneficial to the blade? If so how is it done best?
Any tips for better treatment of the steel would be appreciated!
 
If you don't have full HT equipment, then sending it out is needed. It requires a programmable oven, Stainless HT wrap, and either a sub-zero dry ice bath or cryo in liquid nitrogen.

Because you haven't filled out your profile with the necessary info ( age, location, interest and hobbies, occupation, etc. ) I don't know which HTer to suggest you sending it out to. Filling it out is a good idea for other reasons, too.

Cryo is done by lowering the blade to below -300F. Sub-zero treatment is lowering the blade to around -100F. In either case, the goal is to complete the martensitic transformation from the austenite. It is actually the bottom of the quench cooling part of HT. Full cryo in LN also does some things to the carbides. A blade that receives either treatment as the end of the quench cooling ( before normal tempering) will be slightly harder and a bit tougher than one just cooled to room temperature in the quench phase of HT.
 
Ok thats good to know! Not sure if I should start a new thread or just ask on this one, you can let me know if i should start a new thread. But my second question would we with regards to steel choice for fixed blade knives. Ive heard, and correct me if im wrong, CPM D2 is really good at making a sharp edge but is kind of brittle because of this ability. I also like that it is "semi-stainless" so it wount rust like crazy. I would like a blade with some more toughness though, something that could stand up to some beatings and not break on me. Do you have any recommendations?
 
For stainless blades, the choices are many. Nothing wrong with "old reliable" 440C. D2 is also a good steel. However, if "good" isn't good enough, there are improved steels for knifemaking.

The CPM steels offer finer grain and are a real improvement over the non-CPM versions. This is because the CPM process makes the steel up in little granules of perfectly alloyed steel. The distribution of the alloy ingredients and small grain size makes for a very reliable edge.

My favorite, and a real great steel, is CPM-S35VN. It offers a improvement in toughness over S30V, and has better edge retention than 440C or D2. Crucible claims a 15-20% improvement in toughness over S30V. Properly heat treated it is a superb knife steel.

What makes some steels better than others is the type of carbides they form. Chromium carbides are hard, but are more brittle and larger than the tougher and smaller vanadium and niobium carbides.
 
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