Describe TWO methods of how a non-ferrous metal can be heat treated. – NABTEB QUESTION

(i) A non-ferrous metal (aluminum) can be heat treated by annealing after cold working which increases hardness. This can be done by heating with blow pipe and smeared with soap or match stick rubbed on the metal. When soap turns black, it means the annealing temperature is reached and then allowed to cool to room temperature.

(ii) Cropper can be heat treated after welding. The joint is heated to about 6000c and then quenched with water or allowed to cool at room temperature