No cryo on 3v data sheet?

[Dave Hill Earthcrack]

Long time lurker, first time posting. Blade forum threads have been instrumental in my knifemaking/blade smithing path. Many thanks to the BF community!
To my main question. I am interested in working 3V in the future. Many makers put 3V (and other steels) through a cryo cycle to reduce RA (if I'm getting it). If a Cryo cycle has a significant effect to the end product, why no mention in 3V's data sheet.
Have objective and repeatable tests been done? If so where can I see the results? Just curious. Thanks!

Dave
Earthcrack Knives

 

[Cobalt]

I could be wrong about this, but cryo is not a spec in any steel for any industry, yet. There are many in different industries who still do not believe cryo offers positive benefits. That may be part of the reason.

 

[Steel130]

I could be wrong about this, but cryo is not a spec in any steel for any industry, yet. There are many in different industries who still do not believe cryo offers positive benefits. That may be part of the reason.

Actually Bohler recommends cryo on quite a few of their stainless steels, M390 for example being one. They recommend it for improving the corrosion resistance.

 

[Dave Hill Earthcrack]

Thanks for the replies. Both responses are helpful. After thinking about it, knives probably account for a small percentage of industrial output of 3v, and would be impractical to include every possible way to heat treat.

 

[shqxk]

There are two major method to get rid of RA in high alloy steel beside the austenitizing temperature and cooling rate.

First is the freeze treatment, by convert retained ausenite to martensite as it put the steel to below the Mf point.
Long time cryogenic also allow the precipitation of very fine ETA carbides on tempering, result as the more percentage of martensite and more wear resistance.

Second is to tempering at 1000-1050F which also known as secondary hardening tempering. At this temp most RA will be dissolve thus higher carbon to the matrix that will lead to precipitation of secondary carbides (higher wear resistance and lower corrosion resistance).

For most high speed steel with higher C, V, Mo, W like CPM-M4, RA amount will be too much to be handle by freeze treatment alone, you need SH tempering to do it.

For CPM-3V, if you plan to use 1050F tempering (secondary hardening range) you can skip cryo because at that temperature most RA will be dissolved.

But keep in mind that SH range tempering are invent for tool-stuff which need to be tough, wear resistance and high hot hardness in thick cross section.
For knives application, the stronger matrix and higher edge stability are vastly prefer over above.

So for CPM-3V I will suggest you to apply combination of faster quench and as-quench cold treatment then you can use the 400F tempering for stronger martensite structure, higher edge stability in thin cross section with out concern on RA.

 

[Matthew Gregory]

I could be wrong about this, but cryo is not a spec in any steel for any industry, yet. There are many in different industries who still do not believe cryo offers positive benefits. That may be part of the reason.

They may not specifically state 'cryo', but instead may say "freeze" or even offer specific temps (-95° F for AEB-L, for example).