<Original Papers>Evaluation of Residual Stress in Laser-peened High-strength Steel by X-ray Diffraction Methods

[Synopsis] Laser peening can introduce compressive residual stress to the surface and, therefore, is effective in enhancing the fatigue strength. This study used laser-peened high-strength structural steel to compare the residual stress near the toe of the welded zone measured by two type of X-ray diffraction methods, "Sin^2Ψ method" and "Cosα method". The Cosα method is recently developed method, whereas the Sin^2Ψ method is conventional method. It is concluded that the Cosα method can apply to residual stress measurements in the toe of the welded zone, because surface and depth distributions of residual stress measured by two type of methods were agree rather well. Moreover, effect of laser peening conditions on surface residual stress on high-strength structural steel is investigated by using the Cosα method