440c How to Harden???

[Aziz Günsel]

hi. I have 440c stainless and what ever I do I cannot make it over 50hrc and a even hardness anyone know how??... thank you

 

[kdnolin]

Do you have experience heat treating stainless?

 

[Stacy E. Apelt - Bladesmith]

https://www.crucible.com/eselector/prodbyapp/stainless/cru440cs.html

 

[Kevin McGovern]

hi. I have 440c stainless and what ever I do I cannot make it over 50hrc and a even hardness anyone know how??... thank you

If you are trying to harden it in a forge, that won't work.

 

[MBB]

Curious as to how much cryo helps the HRC with this steel. 59 HRC at quench sounds like a crap ton of retained austenite.

 

[Stacy E. Apelt - Bladesmith]

IIRC, it pops up about 2 points with cryo. 440C isn't a high hardness steel. I think the last 440C I did was around Rc60 after temper.

Now that I am home, here is my HT regime:
The blade must be enclosed in a stainless foil packet to keep all oxygen away from the blade.
Pre-heat at 1400F ( 760C) and hold for 10 minutes.
Raise temperature to austenitize at 1900F (1040C) and hold for 30 minutes.
Air cool or use aluminum quench plates. ( quench plates are best to prevent warp)
Cool in water to room temperature.
Immediately chill to at least -95F (-70C) for 30 minutes. Cryo will gain a little extra hardness.
Allow to warm to room temperature.
Temper at 375F (190C) to 400F/205C for two hours, cool in water to room temperature, and repeat the temper for a second two hours.

 

[MBB]

Thanks, Stacy! That was exactly what I wanted to know.

 

[Ian Fifelski]

hi. I have 440c stainless and what ever I do I cannot make it over 50hrc and a even hardness anyone know how??... thank you

Tell us a bit about your heat treat method.