Patent ID: 9145594
Filing Date: 2015-09-29
Classification: B21D,C21D,C22C,C25D

Abstract:
1. A method for manufacturing an ultra high strength member comprising: heating a steel sheet at a first heating temperature within a temperature range of 700 to 1000° C.; forming the steel sheet into a shape of a member at the first heating temperature and simultaneously cooling the steel sheet; after completion of the cooling, shear punching the steel sheet into a desired shape to obtain an ultra high strength member; after the shear punching, subjecting the ultra high strength member to a first heat treatment including heating the ultra high strength member at a second heating temperature within a temperature range of 100° C. or higher and 150° C. or lower, and retaining the member at the second heating temperature for 1 second to 60 minutes; after the first heat treatment, cooling the ultra high strength member; and after the cooling, subjecting the ultra high strength member to a second heat treatment including reheating the ultra high strength member at a third heating temperature within a temperature range of 150° C. or higher, but lower than 300° C. and retaining the member at the third heating temperature for 1 second to 10 minutes, wherein the resulting ultra high strength member has a tensile strength of 1180 MPa or more.