Residual stress is known to be redistributed as a result of crack extension. The neutron diffraction method was used to evaluate this residual stress redistribution, using a specimen consisting of a butt-weld-jointed pipe made of type-304 austenitic stainless steel (inner diameter φ=97. 1mm, thickness t=8. 9mm) . Half-elliptical cracks were introduced by an electrical discharge machining at the inner surface of a heat-affected zone. The ratios of a⁄t, for crack depth a and specimen thickness t, were 0. 25 and 0. 5, with aspect ratios a⁄c, for crack half-length c, of 0. 1 and 0. 5. Comparing the residual stress distribution before and after the crack introduction showed that although the residual stress distribution along the line of the ligament at the deepest point of the crack changed slightly in front of the crack tip, it did not change throughout the ligament. This result shows that residual stress redistributes throughout in the whole crack tip region, including the width of the crack.
