Method for improving the formability of steel blanks
AssigneeArcelorMittal
InventorSadok GAIED
Life of this patent
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Abstract
A method to improve the formability of steel blanks, for steels containing at least 5% martensite, and possibly some ferrite, bainite and residual austenite and having an ultimate tensile strength of at least 500 MPa and possibly having a metallic coating layer on at least one side, wherein the steel blank is heat-treated on at least part of its peripheral thickness using at least one heat source, which heats the steel in a heat-treated zone to a temperature between 400° C. and 1500° C. without melting the steel in any points of the heat-treated zone.
Claims18
1-15. (canceled)
A method to improve the formability of a steel blank, the steel blank having a microstructure containing at least 5% martensite in area percentage, and optionally ferrite, bainite and residual austenite, the steel blank having an ultimate tensile strength of at least 500 MPa and having a zinc based metallic coating on at least a portion of an upper face or a lower face, the method comprising the steps of:
- performing wherein a heat-treatment operation is performed on the steel blank by directing a thermal energy Q provided by at least one heat source on at least part of a peripheral thickness of the steel blank to form a peripheral heated portion and a heat-treated volume, the temperature of the heat-treated volume being within the range of 400° C. to 1500° C., wherein an entire volume of the steel blank stays solid during the heat-treatment operation, and wherein a thickness of the metallic coating after heat treatment in the area covering the heat-treated volume decreases by less than 30% as compared to a thickness of the metallic coating in areas not covering the heat-treated volume.
Dependencies are inferred from the claim text.