RESIDUAL STRESS MEASUREMENT METHOD

An object of the present invention is to provide a method for measuring a residual stress, the method enabling measuring a residual stress of a fillet portion with high accuracy. In a method for measuring a residual stress according to one aspect of the present invention, in a case in which an angle of incidence of X-rays is denoted by Ψ [°], a fillet radius is denoted by R [mm], a fillet angle is denoted by θ [°], a vertical width of a housing of an X-ray stress measuring apparatus is denoted by W [mm], a width of a detection region of a two-dimensional detector is denoted by D [mm], a complementary angle of a Bragg angle is denoted by η [°], and an interval between a flange portion and an imaginary straight line which passes through a fillet center and is parallel to the flange portion is denoted by a [mm], the following formula 1 is satisfied; in a case in which Ψ ≥ 0, an irradiation distance L [mm] of the X-rays, the irradiation distance L being based on the two-dimensional detector in a calculating step, satisfies the following formula 2; and in a case in which Ψ < 0, the irradiation distance L satisfies the following formula 3. It is to be noted that with respect to an imaginary straight line which passes through a measurement site and the fillet center, the angle of incidence Ψ is positive in a case of tilting toward an axis portion, and is negative in a case of tilting toward the flange portion. D≦W−R1−cosθ+W2sinθ+ψcosθ+ψ≦L≦D2tanηRsinθ+W2cosθ+ψ−asinθ+ψ≦L≦D2tanη