The effect of multi-pass welding on residual stresses in fillet welded built-up steel box sections

One of the main challenges in welding structural sections is selecting the optimal welding sequences to minimize residual stresses and distortions. In welded structural sections, such as built-up steel box sections, residual stresses and distortions can lead to failures due to the non-uniform expansion and contraction of the weld and surrounding materials. This study investigates the impacts of two different multi-pass welding sequences on residual stress and distortion in fillet welded built-up steel box sections, aiming to identify the most effective solution for minimizing residual stresses and distortions in these structural sections. To achieve this, both thermal and mechanical analyses were conducted using the finite element method, implemented in Abaqus software and programmed in Fortran programming language. The numerical study was validated against existing experimental tests documented in the literature, demonstrating good agreement. The analysis revealed that the sequance of welding operations can affect peak residual stresses; with some sequences resulting in lower stresses and distortions. Consequently, an optimal multi-pass welding sequence is proposed to minimize distortion and residual stresses in fillet welded built-up steel box sections.