Recommendation? Preheat kiln necessary for high alloy steels?

Michael.Drinkwine

Michael.Drinkwine

Joined
Apr 17, 2015
Messages
91
I am expanding into higher alloy steels for my kitchen knives and am trying to determine if purchasing a 2nd kiln for preheating is needed or just nice to have. I currently have an Evenheat KO-22.5 and Rockwell tester, and have just purchased a dewar for LN2 (was using dry ice previously.) The steels I am looking at heat treating primarily are: A2, AEB-L and CTS-XHP. Possibly some Cpm-M4 if I'm feeling really masochistic. :)

I have read here that Devin Thomas and others are using a 2nd kiln for preheating, but I have also read (often from the same makers) that preheat on knife blades is not really necessary, and that going straight into a well soaked Aus-temp furnace is adequate.

I am passionate about doing the absolute best job I can on heat treatment, BUT I also don't want to be chasing theoretical/minimal returns on quality that have no real world impact.

Any help from the myriad talented makers on here would be most welcome!

Michael
 
I rarely do preheating, I frequently do a prequench on certain steels. My second furnace is used to do the prequench. The prequench is used to refine the grain on some steels.

A preheat is used on complicated shapes to prevent cracking during the quench because of uneven heating causing stress.

You can do a prequench then a full quench with only one furnace. Many makers do a preheat then raise to full heat in the same furnace also.

Hoss
 
DevinT said:
I rarely do preheating, I frequently do a prequench on certain steels. My second furnace is used to do the prequench. The prequench is used to refine the grain on some steels.

A preheat is used on complicated shapes to prevent cracking during the quench because of uneven heating causing stress.

You can do a prequench then a full quench with only one furnace. Many makers do a preheat then raise to full heat in the same furnace also.

Hoss
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Thank you. I have been asking the same question lately.
 
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