H/T cpm3v

[SBuzek]

I am about to H/T my first 3v blades and was checking crucibles site and they recomend 3 tempers of 1000 deg F or can it be done at a lower temp.
If tempering at 1000 deg should I leave them wrapped in foil to protect them from decarb.
Thanks for any help
Stan

 

[gixxer]

That is an interesting question. I cannot wait to hear from somebody who works with the stuff to find out.

 

[fitzo]

ButcherBlock has experimented with lower-range tempering. If he doesn't see this, make sure and PM him to ask.

If you end up going with the higher range, definitely wrap in foil. The first time I did 3V I tempered out of the foil and the oxidation was heavy.

 

[SBuzek]

Thanks fitzo.
Stan

 

[mete]

You shouldn't get decarb at 1000 F. Above the critical temperature is where significant decarb starts.
Fitzo, describe the oxidation . I would expect heavy temper color but not significant oxide layer.

 

[butcher_block]

3v being a tool/die steel the higher temper temp. is from what i an tell to keep RA to min
i cryo and then temper at 400f

i still do 6 hours of temper time on it
in a nut shell 2025f 20 min soak , plate quench cryo over night and temper in morning
i get 61-62 Rc and still tough enough that i can beat on it in smaller knives (sub6" blade)
big choppers i liek to temper hotter and get about 60RC out of them

 

[fitzo]

You shouldn't get decarb at 1000 F. Above the critical temperature is where significant decarb starts.
Fitzo, describe the oxidation . I would expect heavy temper color but not significant oxide layer.

I certainly wouldn't describe it as looking like it was scaled or decarbed. The blade turned mostly black, with shades of grey and a little deep blue in there. It was definitely significantly thicker than normal tempering and opaque, and a thicker layer than what I get taking 1084 through an extended annealing cycle. It was ugly.

Definitely not worth tolerating to avoid re-wrapping after cryo.