ANNEALING METALS

Annealing is a heat process whereby a metal is heated to a specific temperature /colour and then allowed to cool slowly. This softens the metal which means it can be cut and shaped more easily. Mild steel, is heated to a red heat and allowed to cool slowly. However, metals such as aluminium will melt if heated for too long.

Aluminium can be annealed but care must be taken whilst heating. The flame should be held at a distance to the aluminium so that it gives a generalised heating to the metal.
A ‘trick of the trade’ is to rub soap on to the surface of the aluminium and then heat it on the brazing hearth. It takes only a short time for the soap to turn black. The brazing torch should be turned off immediately and the aluminium allowed to cool slowly. It is now annealed and should be very soft and malleable.

Note:
The annealing is done on metals to reduce their brittleness and to reduce the stresses in metals after the heat treatment process. In annealing the metal is heated and cooled in furnce slowly