HIGH-STRENGTH ALLOYED ALUMINUM-SYSTEM PLATED STEEL SHEET AND HIGH-STRENGTH AUTOMOTIVE PART EXCELLENT IN HEAT RESISTANCE AND AFTER-PAINTING CORROSION RESISTANCE

摘要

The present invention provides a hot press method used for producing a high-strength member for an automobile and, in particular, a part which requires high-strength, such as an undercarriage component of an automobile. More specifically, the present invention provides an aluminum plated steel sheet or an aluminum-zinc plated steel sheet suitable for high temperature forming (hot forming) wherein high strength is obtained after high temperature forming, and a method of producing the same. Also, the present invention provides a hot dip aluminum plated steel sheet which suppresses the alloying reaction of a plated layer during press forming and has beautiful appearance, and an aluminum-system plated steel sheet for hot press having excellent after-painting corrosion resistance. Concretely, the present invention is a high-strength aluminum-system plated steel sheet excellent in heat resistance and after-painting corrosion resistance, characterized by having an Fe-Al-system coating containing, in mass, Mn and Cr of more than 0.1% in total on the surface of the steel containing, in mass, C: 0.05 to 0.7%, Si: 0.05 to 1%, Mn: 0.5 to 3%, P: not more than 0.1%, S: not more than 0.1% and Al: not more than 0.2%, and, in addition, one or more element(s) selected from among Ti: 0.01 to 0.8%, Cr: not more than 3% and Mo: not more than 1%, so as to satisfy the following expression (1): Ti + 0.5xMn + Cr + 0.5xMo > 0.4 ... 1