SURFACE TREATED STEEL SHEET HAVING EXCELLENT WORKABILITY AND CORROSION RESISTANCE OF WORKED PORTION, AND METHOD FOR MANUFACTURING THE SAME

摘要

PROBLEM TO BE SOLVED: To obtain excellent workability, corrosion resistance of worked portions and roll formability of a surface treated steel sheet consisting of an Al-Zn hot dip coated steel sheet of 20 to 95 mass% in Al content in a plating film as a substrate steel sheet. SOLUTION: The plating film is obtained by undergoing a heat history of at least the following (a). This steel sheet has a chemical conversion treated film containing prescribed amounts of Cr and a thermosetting organic resin obtained by subjecting the surface of the plating film described above the chromate treatment under specific conditions: (a) The heat history in which the plating metals subjected to hot dip plating is warmed up and heated to temperature T( deg.C) of the range from 130 to 300 deg.C after solidifying and thereafter the average cooling rate form the temperature T( deg.C) to 100 deg.C satisfies C( deg.C/hr) expressed by the following equation (1) or below and/or the heat history in which the average cooling rate from the temperature T( deg.C) of 130 to 300 deg.C after the solidification of the plating metals subjected to the hot dip plating to 100 deg.C satisfies C( deg./hr) expressed by the following equation (1) or below: C=(T-100)/2...(1).