Heat Treat advice for 440C 3/32" stock

G

Greg Garner

Joined
Sep 15, 2005
Messages
11
Hello all,

I am a new member of the Forum and would like to introduce myself. I started making knives in 1988 and continued making them as a hobby until 1997. I made about 60 fixed blade knives during that time but never performed my own heat treating. Work and family has kept me away since '97 but I am getting back into it and want to finish some folders I started back in '97.

I have purchased a SugarCreek heat treat oven with the computer control unit and have the tool wrap. I need to heat treat blades, locking bars, and spring holders made from 440C precision ground 3/32" stock. I have checked the web for heat treat information and have some conflicting information. What I have found is:

For 3/16" stock (twice as thick as my stock) I see that I harden at 1880 F degrees for 15 minutes. Air cool to quench down to about 125 F degrees. Then temper at 225 F degrees for 2 hours. Temper only once.

The other information says to harden at 1850 F degrees for 20-25 minutes and then air quench. Then it says to temper at 220 F degrees for 2 hours but to do the temper process twice.

Any advice as to which is "more" correct? Also, do you use a special measuring device to check for when the parts are cooled to 125 F degrees other than a standard thermometer?

Thanks for any help you could provide.

Greg
 
I would ,for your stock, use 1850 F for 15 min. I would also temper twice ,2 hours each. But where did you get 220 for the temper ??? Is that C or F?you won't get any tempering at 220F . But at 220C [428F] that would be fine.
 
Can't offer any advice here, but I will say.......Welcome to the Forums..........

Great place for info and meeting new friends.

Robert
 
I should have added - A good source for HT info is www.crucibleservice.com They recommend 400-800F depending on desired hardness. 440C is ,in that thickness , air hardening, so either air or oil quench. Now that you have a furnace you will be able to HT complex alloys like the stainless steels properly. This is a good place to ask questions .Welcome to the forum.
 
From Admiral Steel

440C Stainless
Typical Analysis
C 1.03 Mn .44 P.025 S.001 Si .65 Ni .30 Cr 16.68 Mo .50 Cu .16
Hardness
R/B 92-95

Heat Treating Information
Initial Quench Temperature - 1850°F-1950°F max
Hold for 5 minutes
Quench in warm oil or air cool
Do not overheat (too much time or too high temperature)

Hardening & Tempering Information
300°F - 1 hour - R/C 60
500°F - 1 hour - R/C 57
800°F - 1 hour - R/C 56

-----------------

added by me - plate quenching strongly recommended. Also good to cryo and double temper.

Rob!


 
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