Heat Treating - Can someone help me understand what Murray Carter is doing?

[stezann]

Practice and a controlled work environment. Light and room temperature for example. My forge and kiln behaved very differently from season to season before I acquired climate control.

I agree and i came to remeber athmosphere moisture differences having a profound influence on decarburation and scaling dynamics

 

[Carcara]

Here is a good place to ask as any, although Murray does not do this, some Japanese smiths heat treating by eye will quench on a falling heat. They will take their blade above their quenching temp let it air cool to where they want it and then quench. Seems to me that might be a way they get their hypereutectic carbon into solution? With sufficient grain refinement before hand, any grain growth might be compensated for?

 

[Rick Marchand]

I don't think it has anything to do with bringing more carbon into solution but rather purposefully growing the grain for a more aesthetic effect in the hamon. They probably let the heat fall back down as to lessen the chance of cracking. I am totally formulating this hypothesis based on the little I do know about metallurgy. I may be dead wrong but it makes the most sense to me. They probably knew this and willingly sacrificed structural toughness for beauty.

 

[Carcara]

I was talking about laminated kitchen knife makers, not swordsmiths manipulating hamon.