Reducing grain size in pattern welded damascus steel

I wanted to jump in here quick to say something to you guys, but Mr Straub stole my thunder!!! I had skimmed over this thread originally, because I don't forge and don't really care for damascus or pattern layered steels, but the discussion has been awesome. Learning quite a bit from you guys. I did just get through reading some of Mr Cashen's notes on his site, some of it discussing the reduction of grain size with a hammer vs heat. Hammer blows indeed cause new nucleation points (I did not know that at all), and so does heating and cooling. The idea being that when the steel is structurally transformed by heating to austenitizing temps and then air cooloed, it is affected uniformly throughout, whereas hammer blows are random and not as uniform. Thanks for all the great discussion!
 
Induction heating might be as fast or faster than salt with less danger. I have not worked with it, but its been around a while. There is a smith that does his forging with an induction heater. I can't remember his name though.
 
Well induction heats things up from the inside to the outside :) It is indeed very fast. I wonder how temperature is controlled and how accurate it can be. And... induction heaters are very expensive... Especially when you need big one's...
 
Well, I didn't say there weren't down sides :). I think the outside-in heating would be a non-issue for knife blades. I've seen chisels heated that way on a conveyor belt passing through an induction coil, then water or oil quenched a few feet later, still on the conveyor. I won't say it was optimal, but it worked. The variables are voltage, frequency, amperage, and coil shape. Maybe more. I have never done it, but it is fairly common in industry. One of my class mates went to work for an axle maker, and they induction hardened the outside.
 
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