GR wrote:
HI Mickmini
To soften the copper you have to drop it in water after you bring it to red hot. Having made a few solid copper head gaskets for grey motor holden's mg's and 68mm small bore Minis I can tell you they will not seal as they are too hard. You have to quench it in water after heating it, get a strip of copper and try it.
Graham Russell
A:In annealing of copper, the heating is the important part. The rate of
cooling is immaterial.
Whether you allow it to cool naturally or drop it into water makes no
difference to the final softness.
.
Traditionally, we drop it into water because that's what we were told, but
it is not necessary. It's only a matter of convenience
The copper will maintain it's soft crystal structure after annealing at any realistic cooling rate (from very slow like letting fire die down to fast like throwing it in a bucket of water). Generally, I would suggest water cooling to prevent excessive oxidation of the surface. Steel (iron + carbon) on the other hand will change it's properties dramatically upon rapid cooling . However, it is possible to cool copper fast enough to make it into a brittle material. This normally involves cooling rates of greater than 10 million degrees C per second which can only be obtained by spraying a very thin film on to a very cold surface (this equipment is very expensive).
Try it both ways and see for yourself.
Dave
