Heat and surface treatments- Terms
AGING – The process of holding metals at room temperature or at a predetermined temperature for the purpose of increasing their hardness or strength by precipitation. Aging is also used to increase dimensional stability in metals such as castings. AGE HARDENING – Change in the physical properties, e.g. , hardness and strength, that occurs in certain light metals after heat treatment. ALLOYING OF METAL – The addition of varying proportions of other elements to a basic metal in order to produce an alloy having specific properties. ANODIC TREATMENT – Formation of a protective layer of oxide on the surface of aluminium and its alloys by electrolytic action, in order to resist corrosion. ANNEALING – A heat treatment in which metals are heated and then cooled very slowly for the purpose of decreasing hardness. Annealing is used to improve machinability and to remove stresses from weldments, forgings and castings. Also used to remove stres...