Method of manufacturing a compound steel material of a high corrosion

Abstract

A compound steel material of high corrosion resistance is manufactured by alloying a carrier material of deep-drawing grade with a carbide and nitride forming substance, compounding the alloyed carrier material with a chromium steel material of normal carbon content, followed by annealing the compound steel material at a temperature and for a time period sufficient for the carbon content of the ferritic chromium steel coating layer to be reduced to between 0.001 and 0.003% so as to increase the corrosion resistace of the chromium steel material to that of a superferritic material. Prior to annealing, the compound steel material may be rolled to a fine sheet. The carrier material used in the method of the invention is a deep-drawing steel of at most 0.12% of carbon, while the ferritic chromium steel material has at most 0.1% of carbon prior to the annealing. The carbide and nitride forming substance may be titanium whose content in the alloyed carrier material is preferably between 0.5 and 2%. The thickness of the ferritic chromium steel coating layer is between 50 and 500 .mu.m, the annealing temperature between 650 and 900.degree. C., and the annealing time period between 8 and 72 hours.