High strength member, method for manufacturing high strength member, and method for manufacturing steel sheet for high strength member

A high strength member comprising a bending ridge line portion formed from a steel sheet, the member having

• a tensile strength of 1470 MPa or higher,
• a residual stress of 300 MPa or lower in an end surface of the bending ridge line portion, and
• a Vickers hardness (HV) of 200 or higher and 450 or lower in the end surface of the bending ridge line portion.

A method for manufacturing a high strength member, the method comprising

• a bending work process of cutting a steel sheet having a tensile strength of 1470 MPa or higher and performing bending work on the cut steel sheet and
• an end surface treatment process of heating an end surface, which has been formed by cutting, at a temperature of 400° C. or higher and 900° C. or lower for more than 0 seconds and 10 seconds or less after the bending work process.

A method for manufacturing a high strength member, the method comprising

• an end surface treatment process of cutting a steel sheet having a tensile strength of 1470 MPa or higher and heating an end surface, which has been formed by cutting, at a temperature of 400° C. or higher and 900° C. or lower for more than 0 seconds and 10 seconds or less and
• a bending work process of performing bending work on the steel sheet, which has been subjected to the end surface treatment process.