Neutron diffraction measurements of stress in an austenitic butt weld

Abstract

In this study, the residual stress distribution in a double-V butt weld plate of 304-type austenitic stainless steel was measured using the neutron diffraction technique with the diffractometer for residual stress analysis (RESA) located in the JRR-3 (Japan research reactor number 3) at the Japan Atomic Energy Agency. Coupon samples were cut from the weld plate in order to follow the changes in chemical and microstructure or effects from type-2 intergranular strains. The residual stresses were measured using the {111}, {002}, and {220} reflections. The residual stress derived from {002} reflection is sensitive to intergranular effects, so that when the analysis ignored intergranular effects, the stress variation for the {002} reflection was different from the stresses derived from the other reflections. However, the stress distributions evaluated from the lattice strains for all the reflections were in good agreement, within the error bar of ± 35 MPa, after correcting the measured strains by subtracting the intergranular strains derived from the coupon measurements. The consideration of intergranular effects thus improves the accuracy of neutron stress measurements of weldments.