Going to heat treat cpm 3v.

M

M Wadel

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Sep 11, 2005
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I've rough profiled a quite large chopper/survivalknife and now its time to deciede what heat treatment I should give it. I still have the option of plate quenching it since the sides of the blade are not ground yet.

Would you guys recommend plate quenching instead of air? I see in the pdf http://crucibleservice.com/datash/ds3Vv5b.pdf?CFID=147779&CFTOKEN=71526630
they also suggest intrerupted oil quench (down to 1000F in oil then let cool in air), is this better than plate/air?

The pdf is pretty much a joke infowise, no Ms temp, no TTT-diagrams, no brittle tempering range etc, no nothing. Anyone know if I can get this info from crucible?

Ok lets talk austenitizing temperature. the higher the temperature the more retained austenite right? Do I want a lot or little? I know this doesnt really matter when tempering in the 1000F range, but what if I dont want as much carbides? Can I temper it below 1000? What temps should be avoided because of brittleness?

What hardness would you suggest for a large 10 inch chopper? I want hard but no chipping, I want tough but no edges bent/dented.

I would like to harden at the temp that gets me most toughness, quench as aggressive as the material permits, cryo it, then temper somewhere that gets me 60-61 hrc if possible, I dont really care about how much carbides I get, well I do but its not the most important thing for me.

Is it really necessary to temper it 3 times?
 
CPM 3V is very tough and very wear resistant. Grinding after HT will be VERY difficult .
The information is all there .For max toughness - 1875 F with temper 1000 F. Plate quench will work well.
 
Says best response is salt quench. That probably means it benefits from a fairly rapid quench. Plate quench is faster than air, that might be a good thing.
 
mete said:
CPM 3V is very tough and very wear resistant. Grinding after HT will be VERY difficult .
Click to expand...

Yeah I had a feeling it was going to be that.

Do you think there is anything to gain with cryo when tempering at 1000F?

Will a plate quench give a higher hardness than that oil-air thing, or molten salt?

I wonder if a plate quench give higher or lower "as quenched" hardness than whats in their pdf for each temperature.
 
Hi - for what it's worth, I just looked up 3V in my crucible book to see if there is any additional useful info. Since you're planning to do a chopper, I thought you might like to know that hardening at 1875 and tempering at 950F for a hardness of 58RC gave the highest impact toughness in the steel vs 60RC@1950 and 62RC@2050. I don't know if this was strictly because of the hardness difference or if there is a significant change when austentitizing at the low end.
 
Since they make no mention of cryo for 3V it's obviously not useful ! The lower austenitizing temperature dissolves less carbides so the martensitic matrix is tougher.
You'll be hardening in foil because of the high temperatures so plate quench is fast and convenient. Don't worry about hardness too much as there's is usually done on 1" thick samples and you should get a bit harder.
 
i do it all wrong so far as the books say
2050 f plate quench LN2 over night then temper at 400 on most the stuff 1000 on big choppers just in case
i like 3v at 61-62 and at 60-61 i have never had it be chippy on me
might be in part how low the carbon is in it and the fact that even more of it gets pulled to make V carbides
but hey im just guessing
 
When plate quenching I dont need to remove the blade out of its foil? Do I need to make special plates that have the inverse shape of the blade or will regular flat plates work just as good? I've been thinking about flat plates not having full contact but then again it might suck the heat out fast enough anyway, I dont know, it was several years ago I read about plate quenching.
 
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