Working on heat treating some 440C. My question is do I need to unwrap the blades from the foil before quench? Or can I put the whole thing foil and all into the oil?
Thank you
No oil at all. I plate quench mine between two 1" thick plates of aluminum still in the packet. I don't miss the oil from heat treating high carb steels at all.
That's an approach I hadn't heard, but I can definitely see the advantages. If you don't mind me asking what temps and times do you use? What hardness could I expect?
Preheat and go to 1425 deg, hold for 10 minutes and go up to 1900 deg and hold for 20 minutes. Quench between thick plates under clamps with compresses air cooling till I can hold by hand. I am working with 1/8" and under. So far they are coming out at RC60. Temper them back with two one hour cycles at 250deg and hit at RC 59. I just started trying a deep freeze in dry ice and alcohol but too early to tell if it's work the trouble.
Heres Alpha knifes and Crusable's stuff on 440c, it gave me a starting point to work from.
here's a "sticky" Darren Sanders put up on 440:
(Why not try for air-quenching and leave the wrap on. I think for oil you most assuredly would need to take it off.)