THERMALLY TREATED METALLIC COATED FERROUS BASE PRODUCT HAVING IMPROVED DUCTILITY AND METHOD OF MAKING PRODUCT

摘要

This invention relates to an aluminum-zinc alloy coated ferrous product whose coating is highly ductile, and to the method whereby such improved coating ductility may be realized. The process is characterized by the steps of thermally treating the aluminum-zinc alloy coated product by heating to a temperature between about 200 DEG F. (93 DEG C.) and 800 DEG F. (427 DEG C.) and holding for a period of time to effect metallurgical structure changes, among them being the precipitation of a second phase incoherent with the matrix, followed by slow cooling to at least 400 DEG F. (205 DEG C.). The resulting product is characterized by an aluminum-zinc alloy coating with a hardness no greater than about 115 VHN, and preferably no greater than about 110 VHN.