In-situ Residual Stress Analysis during Thermal Cycle of a Dissimilar Weld Joint Using Neutron Diffraction and IEFEM

Abstract

Residual stress is one of important issues for optimizing the manufacturing process and ensuring the structural integrity of welded components. Many results on the issue have been reported, however, the residual stress relaxation mechanism of dissimilar weld joint by the thermal cycle is not yet enough clarified. In this study, the residual stress evolution process of a dissimilar weld joint during thermal cycle was investigated using in-situ neutron diffraction technique and the Idealized Explicit Finite Element Method (IEFEM). The base materials of the dissimilar weld specimen were a SUS316L stainless steel and a NCF600 nickel alloy. The obtained results clearly show that the residual stress especially in the NCF600 side decreased in the first thermal cycle due to yielding of the NCF600. This yielding was caused by an estimation that the total stress, which is the sum of the initial welding residual stress and the thermal stress, exceeded the yield strength of NCF600 during the heating process.