Though not a metalurgist, I coincidentally own a full set of Metals Handbook from the American Society for Metals. How I came by them is a long story. Anyway, reading on annealing (copyright prevents my posting the actual page):
"Annealling is primarily a function of metal temperature and time at temperature. Except for alpha-beta alloys and certain precipitation-hardening alloys, the rates of heating and cooling are relatively unimportant. Source and application of heat, furnace design, furnace atmosphere, and shape of workpiece are important, because they affect the uniformity of results obtained, finish and cost of annealing."
The annealing process causes grain growth in the metal. I suppose this results in softness due to less total grain surface to combat when moving grains against oneanother. Anyway, the annealing temperature for low phosphorous copper (I'm guessing that might be what we get) is 600F-1200F. At the lower temperature considerable time would be required (for formal work, the book says, like, 40 minutes) and, then, you still don't end up with the softest part, as higher temperatures are capable of generating greater final grain size, regardless of how much longer you keep it at the lower temperature. At least, this is how I am reading the charts and data in front of me. By the way, my attempt at annealing consisted of getting a dot of glow to move all over the gasket. While there was an obvious change in hardness, this was clearly inadequate according to the book.
My interpretation of the reason that fast cooling is not so important is that the grains have already grown and the shrinkage (don't be alarmed) would be a small percentage compared to growth due to recrystalization. OK, already, enough!
Back to my origianl question: do others sand or lap their head gaskets due to burrs from the stamping die?
Richard L.
