METHOD FOR MANUFACTURING BLANK TO BE COLD-PRESS-FORMED OF ALUMINUM ALLOY SHEET, COLD PRESS-FORMING METHOD BY USING THE SAME, AND FORMED ARTICLE

摘要

PROBLEM TO BE SOLVED: To ensure the high formability of a blank to be cold-press-formed of an aluminum alloy sheet, which is mainly used for an automotive body sheet, and simultaneously enhance paint baking hardenability.SOLUTION: This method for manufacturing the blank includes: subjecting the rolled sheet of the Al-Mg-Si-based aluminum alloy to solution heat treatment, rapidly cooling the sheet, and then subjecting the sheet to preliminary aging treatment at a temperature of 60°C or higher but lower than 120°C for 5 minutes or longer to produce the blank; and subjecting a region determined as a region to be heat-hardened out of the blank to partial heat treatment, with which a punch shoulder is brought into contact mainly during a cold press-forming operation. Thereby, the strength in the region is enhanced, and the strength difference is imparted in the plane of the blank. Alternatively, the method includes: determining a region to be heat-softened separately from a region to be heat-hardened; and heating the region to be partially heat-softened on a different condition from the condition for heating the region to be heat-hardened as the partial heat treatment to soften the region.