Hi folks,
I'm still hunting for the 4340 hardening details. I have some annealed stock that I want to make a press form with.
Waveicle
4340 recipe
!
Never mind, found it. 
"Heat to 830 oC - 860 oC, hold until temperature is uniform throughout the section, soak for 10 - 15 minutes per 25 mm section, and quench in oil, water, or polymer as required.
*Temper immediately while still hand warm."
Here:
http://www.interlloy.com.au/
"Heat to 830 oC - 860 oC, hold until temperature is uniform throughout the section, soak for 10 - 15 minutes per 25 mm section, and quench in oil, water, or polymer as required.
*Temper immediately while still hand warm."
Here:
http://www.interlloy.com.au/