Numerical evaluation of the effects of a mitigation treatment on the residual stresses of a tubular dissimilar metal weld

Dissimilar metal welds (DMW) between ferritic steel pipes and austenitic steel nuclear components are located in the primary coolant circuit of pressurized water reactors. Those tubular joints, made using an Inconel weld filler metal which is known to be susceptible to stress corrosion cracking, showed in the past some weaknesses, as encountered in particular in the USA and Japan, where stress corrosion cracks have been observed. In this context, the goal of this work is to optimize the manufacturing of these dissimilar joints in order to decrease the negative effects of welding residual stresses regarding these integrity defects. We present in this paper a numerical evaluation of the residual stresses of a specific tubular dissimilar weld, and the numerical setup and evaluation of a mitigation treatment which allows redistributing more favorably the residual stresses. The present work focuses on identifying mitigation process key parameters affecting the residual stresses field. The feasibility of this mitigation treatment is quite encouraging for the studied geometry and materials which could justify an experimental evaluation in the future.