Preheat/ normalize

[Kevin McGovern]

When a heat treat procedure states to preheat to a lower than aus temp and normalize, then to ramp up to the aus temp and hold for a period, does this mean blades go in at the preheat temp and stay in until the soak is complete?

 

[Stacy E. Apelt - Bladesmith]

Yes. Once in the oven, they stay there until removed for the quench.

Usually, the term is "Pre-heat and equalize". Normalizing is slightly different, but I have seen then two terms used interchangeably.

 

[Jrmysell]

So do you put them in a cold oven get to the pre heat, equalize then ramp or do you heat the oven to preheat, put the blade in, bring back to temp, equalize and ramp?

 

[samuraistuart]

No, it's generally not a good idea for a knife to be placed in a cold kiln and then ramped up to temp, whether it's a pre-heat temp or austenitizing temp. Once the kiln is at the desired temp, then place blade in. Soak at pre-heat temp for the required time, then allow the program to ramp up to aus temp (with the blade in of course), soak at aus temp if required, quench.