Evaluating residual stress behaviour in 316H stainless steel using neutron diffraction

In this study, the residual stress generation and relaxation in 316H stainless steel subject to systematically selected thermo-mechanical pre-treatments have been investigated by neutron diffraction. These pre-treatments were designed to reflect the thermo-mechanical history that parent material could be subject to during a welding cycle. The neutron diffraction measurements were made using neutron spallation sources at the Rutherford Appleton Laboratory and at the Paul Scherrer Institute. The underlying principle of neutron diffraction macro- and micro-stress measurement is briefly described. The derived lattice strain, residual stress and the rates of relaxation following thermal exposure at a temperature of 550°C are shown to be a function of microstructure. The results are discussed in terms of the role of microstructure on the magnitude of quenching introduced residual stress fields and creep deformation behavior encountered during stress relaxation at high temperature.