ArcelorMittal S.A.
METHOD FOR FORMING A COLD ROLLED, COATED AND POST BATCH ANNEALED STEEL SHEET

Abstract:

A method for forming a cold rolled, coated and post batch annealed steel sheet is provided. The method includes cold rolling a steel sheet; coating the cold rolled steel sheet with a zinc or zinc alloy coating, the cold rolled, coated steel sheet having an initial hole expansion and an initial yield strength and post batch annealing the cold rolled, coated steel sheet at a tempering temperature in a range from 150 to 650.degree. C., the post batch annealed steel sheet having a final hole expansion and a final yield strength. The steel sheet includes (in wt. %) C--0.1-0.3%, Mn--1-3%, Si--0.5-3.5%, Al--0.05-1.5% and Mo+Cr being between 0-1.0%. The final hole expansion is at least 80% greater than the initial hole expansion and the final yield strength is at least 30% greater than the initial yield strength.