Finite Element Analysis of Thermal-Induced Stresses in Submerged Arc Welded Chromium-Molybdenum Steel and Their Mitigation through Heat Treatment

Abstract

The current study comprises thermal-induced stress distribution in submerged arc welded chromium-molybdenum (Cr-Mo) steel plate and its mitigation through pre- and post-weld heat treatment. Single-sided single-pass square butt weld joints were investigated for three different cases of welding, post-weld heat treatment (PWHT) and preheating and PWHT. Deep hole drilling (DHD) was employed to estimate the residual stresses across the plate thickness in the two most thermally instigated sections, i.e., FZ and HAZ of the welded joint. Finite element modeling was also carried out for welding and heat treatments. The volumetric double ellipsoidal heat source, element birth and death technique, solid-state phase transformation and creep phenomenon were incorporated in FE modeling. Post-weld heat treatment was found efficient in controlling residual stresses in both FZ and HAZ. However, post-weld heat treatment on preheated weld efficiently mitigated the residual stresses for much lower tensile values in FZ. Preheating also improved the uniformity of the residual stress distribution across the weld thickness in the post-weld heat-treated weld. The fair agreement was achieved in predicted and measured residual stresses results. It was also discovered that holding time does not affect the degree of stress relaxation in PWHT.