Abstract: Additions of small but effective amounts of one or more of bismuth, indium, lead and/or tin to an aluminum casting alloy markedly improved the dry machinability of a casting made from the modified alloy. The added elements, which are softer and lower melting than the matrix alloy form as small globules dispersed in the microstructure of the aluminum casting. These globules do not adversely affect the strength or hardness of the casting but enable the casting to be machined without the use of a cooling and lubricating machining fluid.

Abstract: A method of surface treating heat treated members to remove oxide scale. The heat treated members are subjected to a staged series of discrete chemical and physical cleaning steps yielding a substantially scale-free surface readily adaptable for subsequent application of protective coatings.

Abstract: Additions of small but effective amounts of one or more of bismuth, indium, lead and/or tin to an aluminum casting alloy markedly improved the dry machinability of a casting made from the modified alloy. The added elements, which are softer and lower melting than the matrix alloy form as small globules in the microstructure of the aluminum casting. These globules do not adversely affect the strength or hardness of the casting but enable surfaces of the casting to be machined without the use of a cooling and lubricating machining fluid.