Normalizing and heat treating in sub zero tempratures

B

Brad Lilly

Moderator and Awards Boss
I'm out yesterday trying to heat treat a 5160 blade. My normal procedure is to normalize the blade three times then heat to 1500 and quench. Between the normalizing cycles I hold the blade because everything in my unheated shop is below zero degrees. The blade cools off really quickly. Would the blade be getting slightly hard during the normalizing cycles?

Another thought crossed my mind. I want to harden some D2 but I don't have any quench plates. Instead of quench plated would setting the D2 blade on my anvil that is zero degrees do the same thing. I have another block of mild steel 16"x4"x3" to set on top if needed.

I know that zero degrees is not a huge drop from room temperature when dealing with 1500 degrees but my quench oil works better when heated to room temperature. Just a few thoughts for you guys to hash over.
 
D2 is air hardening so you dont "need" quench plates. I would not put it on a cold anvil for fear of warping more than anything else. I would say the reason for your oil working better when warmed is an increase in viscosity more so than actual temp effect during the quench. I have no idea about the 5160.
 
5160 is one of my demons, so I'll just recommend sending it to Ed Caffrey for HT. :)

As for the D2, I think your anvil / heavy bar solution should work as well as quench plates. Remember to leave it in the envelope till cool. This makes it cleaner and also minimizes one sided cooling while waiting to get the second plate on top..
 
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