METHOD FOR HEAT-TREATING STRUCTURAL MATERIAL AND HEAT-TREATED STRUCTURAL MATERIAL

摘要

A heat treatment method of a structural material which includes a bent portion that extends in one direction of the structural material and has a bend in a direction perpendicular to the one direction, includes: determining an effective width of the bent portion e; in a case where an area which includes the bent portion and of which a distance in the direction perpendicular to the one direction from the bent portion is within the effective width e is defined as an effective width area and a ratio of an area in the effective width area which is hardened by a heat treatment is defined as a hardening ratio f M , determining a range of the hardening ratio f M on the basis of a rate of change in a yield stress à Y with respect to the hardening ratio f M ; and performing the heat treatment on the effective width area of the structural material to satisfy the range of the hardening ratio f M .