CPM-S30V heatreat variations

balibalistic

balibalistic

Joined
Jul 14, 2004
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Hey Guy's, i have done alot of searching and read many different opinions regarding heatreat for this steel. i am now more confused then when i started :jerkit: I'm hoping i can get your procudure for s30v and hardness you obtained. i'm not able to do cryo at this point but do have a digital oven.
soak temp, tempering temp and length are what i really need.

thanks fella's, any help is much appreciated :thumbup:
 
1650° for 20 minutes then 1950° for 20 minutes. Take it out and plate quench. I left it untempered at around 62HRc. Had I tempered, it would have been at 450 for two hours twice, quenching in dry ice cooled mineral oil after each temper.
 
ALWAYS TEMPER hardened steel !! You have a choice of high temperature temper [~900 F] or low temp [ ~400-500 F ]
 
OK, why? I can't get anyone to answer and everything I read just says "then temper at. . ." I would rather have the blade at 62HRc instead of 59HRc. Is there something else that happens during the tempering?
 
untempered hardened steel is brittle. By tempering, you make it tougher. the trick is to get a good balance of toughness and hardness.
 
Zaph,
In a side by side use test, you probably couldn't tell a Rc59 blade from a Rc62 blade.
However, you could easily tell the broken or chipped blade from the one that wasn't.

A lot happens durring the temper cycles.
 
ok, blades are hardened. i'd like to end up with around 60rc. so would 450 sound about right for tempering?
 
balibalistic said:
ok, blades are hardened. i'd like to end up with around 60rc. so would 450 sound about right for tempering?
Click to expand...

What temperature and duration did you use to harden? While waiting, they should at least get into a flash temper fairly quickly - maybe 350 or so. Then you can choose the actual temper treatment depending on the results you want. If you used 1950, without cryo, 450 would give you something around RHC57. Nothing wrong with that, since S30V gets its edge retention more from carbides than from steel hardness.

S30V is one steel that really benefits from cryo.

Rob!
 
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zaph1 said:
OK, why? I can't get anyone to answer and everything I read just says "then temper at. . ." I would rather have the blade at 62HRc instead of 59HRc. Is there something else that happens during the tempering?
Click to expand...

There is a lot more to hardness than just hardness. There are the structures involved. That hardness number is just the depth a diamond penetrator.

Your blade, untempered and HRC 62 will be a mixed structure of full hard martensite (perhaps only 60% of the matrix), dead soft retained austenite (perhaps 10%), large amounts of free chromium (~10%), and carbides (perhaps 20%) and probably some other stuff. It will be a much different animal from a simple steel that approached 100% martensite and was tempered down to 62.

At somewhere at around 400F the tetragonal martensite takes a cubic form which (can be) both harder and tougher. Also, not all martensite is equally strained. A very low temperature temper leaks the most carbon out of the crystals that are most highly stressed (and perhaps about to fracture).

Mete can explain this much better than I.

Alas... all steels have a sweet spot, and S30V probably ain't at 62...
 
KnifeMaker.ca said:
What temperature and duration did you use to harden? While waiting, they should at least get into a flash temper fairly quickly - maybe 350 or so. Then you can choose the actual temper treatment depending on the results you want. If you used 1950, without cryo, 450 would give you something around RHC57. Nothing wrong with that, since S30V gets its edge retention more from carbides than from steel hardness.

S30V is one steel that really benefits from cryo.

Rob!
Click to expand...

Yes, i used 1950. i'll try it at 450 and see how it goes. thanks Rob :thumbup:
 
Alright, anneal and re-harden or just temper at 750 w/ cryo as is? Second, and this may be helpful to the OP, allow to cool before cryo or quench with cryo?

Sorry for the hijack.
 
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