The applicability of using low transformation temperature welding wire to minimize unwanted residual stresses and distortions

Fusion welding of steel pressure vessels provides one of the most economic methods for creating such structures. However, the highly localised heat distribution, at the fused region gives rise to non-uniform heating / expansion and cooling / contraction of the weld and the surrounding base material, consequently giving rise to residual stresses and distortion. Several techniques are available to minimize welding distortions and residual stresses [1]. One feasible and efficient mitigation technique, that alters the inherent residual stresses developed during welding, includes the use of low transformation start
temperature welding wire [2e4]. By altering the filler material and metallurgical transformations developed at the fusion zone and heat affected zone, wielded regions at the weld line can give rise to compressive residual stresses [2]. Consequently by establishing the appropriate chemical composition of the welding wire, a significant reduction in welding distortions can be achieved. This study focuses on establishing the merits of using different filler materials to minimize welding residual stresses and distortion through a thermal-metallurgical-elasto-plastic numerical parametric study. Numerical
modelling of butt welded structures using three different filler materials is considered and the applicability of using low transformation temperature welding wire is investigated. The predicted residual stresses and distortions give a significant advance in understanding and control of welding distortion in
welded fabrications. The chemical composition of the filler material and ultimately fused zone composition, leading to reductions in residual stresses and distortions is identified.