Heat Treat Results Today

[CDHumiston]

I heat treated 8 blades today. I do not have the ability to Cryo anything. I was told this could be detrimental, but I like my results.

1st 3 were D2. Preheat 1200° hold 15 minutes. Ramp to 1850° soak for 30 minutes. After one 2-hour temper at 350° blades are 61, 61 and 62.

2nd 3 were 440C. Preheat 1425° hold 15 minutes. Ramp to 1875° soak for 30 minutes. After one 2-hour temper at 300° blades are 61, 60 and 61.5.

3rd 2 were AEB-L. Preheat 1500° hold 15 minutes. Ramp to 1950° soak for 15 minutes. After one 2-hour temper at 350° blades are 60 and 62.

All blades were plate quenched in aluminum in their foil pouches then removed and put in the freezer for an hour. It's all I had.

I am now curious if I need the second 2-hour cycle in the temper oven.

 

[Daniel Carraher]

Yes you need the second temper

 

[Stacy E. Apelt - Bladesmith]

During the first temper some of the retained austenite converted to brittle martensite. It is that brittle martensite that gets tempered in the second cycle. Itvalso relaxes the martensite from the first temper a little more.

 

[Keith Nix]

More than one study has shown that a third temper benefits many high alloy steels.

I'd be very concerned about my blades being in an oven with the coils blazing for an extra 30 minutes. Consider eliminating the preheats.