Investigation on the effect of heat input and clamping positions on residual stress and distortion of the 316L steel butt-welded joint by numerical simulation

Welding residual stress and distortion are one of the important quality criteria of the welded joint; they need to be controlled to a minimum to ensure the workability and aesthetics of the welded structure. The stress and distortion of the welded joint are affected not only by the properties of the material but also by the heat input and the clamping conditions of the workpiece, so studying the influence of heat input as well as clamping types and positions on the stress and distortion of welding joint to find the right heat input and the right clamping positions for the particular welding joint is very important. In practice, the determination of residual stress in welded joints by experiment is very expensive and limited because residual stress can only be measured at the surface of the workpiece but not deep inside, even when using modern measurement methods such as X-ray or neutron diffraction. This paper presents a method to determine residual stress and distortion in welded joints by numerical simulation using the professional software SYSWELD. The calculation results show that the heat input q₁ = 600 J/mm for the root pass and the heat input q₂ = 950 J/mm for the cap pass are the most suitable for the butt welding joint of the 316L steel plate 8 mm thickness. Based on the calculation of residual stress and deformation in all clamping types, it was also found the clamping positions which have the smallest residual stress and deformation for the butt-welded joints.