放射光高エネルギーＸ線を用いた入射角一定法による表面下深部の残留応力分布の非破壊評価

Abstract

A new method is proposed to estimate nondestructively the distribution of the equibiaxial residual stress beneath the surface by using an Eulerian cradle type goniometer. By maintaining a constant value of the X-ray incident angle, the probing depth of X-rays is kept nearly constant, even though sin2ψ is changed. From the slope of the linear relation between the diffraction angle and sin2ψ, the stress value is calculated for a given probing depth. This new method is applied to estimate the residual stress of a shot-peened steel sample, whose compressive zone extended about 150μm below the surface. High energy X-rays of 72keV from synchrotron radiation source, SPring-8, was used for stress measurements. The residual stress distribution estimated by the new method agreed well with that determined by the conventional sin2ψ method with Cr-Kα radiation combined with the method of the successive removal of the surface layer by electropolishing.