[quote=Rocketman]Mark, at least in theory, annealing is a reset to "original" properties of hardness for the alloy used.
DDA
....It is possible/probable that the case will get higher in carbon and deeper with repeat cycles. However, if the anneal is done properly there should be no reason for the case to become brittle....
....DDA
I appreciate the clarifying, as I was thinking it would be unlikely to back the carbon out of a part. I understand that is not what you're saying. Regardless of the care taken in annealing, likely brittleness would come on quenching, as the original thought was to create colors/hardness? But, could a thicker case result in more, for example, tang cracks at screw holes, or warping due to the higher stress an increased percentage of high carbon steel can put on a part when it's hardened?
A curiousity is that gun part annealing, thought to be critically important, is regularly said to be done in a charcoal pack.
