If you are sick of hearing about annealing and quenching and so forth, and you can't imagine how anyone would waste his time on such poppycock, this would be a good time to avert your eyes, turn you head and click on Solitaire (I almost said "cough".)
As previously threatened, I have attempted annealing an old head gasket using my home fireplace. I did try using my wife's hair dryer as a bellows and got a smoke-filled room and ash all over the place. It did, however, create a very hot fire, though it was not necessary for getting the gasket to glow. Just leaving it buried in a bed of well-going coals seems to have been enough.
I did two cycles of heating, the first quenched in water and the second allowed to air dry. On quenching, some, but not all of the scale flaked off, maybe because the gasket could not go directly from glowing to the quench (I had to carry it to the kitchen, a slight miscalculation). For the air-dried sample, there was more scale on the part, but what was left took no more sanding to remove for a given area than that left after quenching.
After each cycle I did a crude deflection force test, as pictured. I tried to see what force would be necessary to deflect a portion of the gasket 1". After the first cycle, the force required was 700-750 gms. After the second cycle the force required was 525-575 gms. Keep in mind that this was a really informal test with me trying to read the scale calibration and deflection at the same time. Also, the gasket did not stay in the coals the same amount of time each time. At minimum, this test should have, of course, started with two unannealed gaskets cooked in the same fire for the same amount of time. After those shortcomings, good science continued to be butchered. Nevertheless, the force differences were enough to identify a true difference in the extent of annealing.
As conclusions, I
do not believe it was air cooling that made the second test softer. I am fairly certain it was getting cooked a second, and probably longer, time. The amount of scale that formed was a bit troubling, as it takes some aggressive sanding to remove. I tried a steel wire wheel but it was eating away at the thickness of the gasket.
Below are some pictures from the effort and a link to a very short video meant to embarrass myself.
Just in case it is not obvious, it is really cold in Chicago, and the prospect of meaningful riding any time within the next three months is looking slim. Therefore, I am significantly distracting myself.
Richard L.
http://www.youtube.com/watch?v=cOul-aIO_lg[/img]