Reliability analysis of thermal cycle method on the prediction of residual stresses in arc-welded ultra-high strength steels

Abstract

The large amount of calculation time is one of the major obstacles to the industrial application of numerical welding simulation. The thermal cycle method is a newly developed approach, which can significantly reduce the computational time. The present work aims to systematically analyze the reliability of the thermal cycle method in the prediction of residual stresses in the arc-welded ultra-high strength steels (UHSS). Both numerical simulation and experiments have been performed for estimating and validating its feasibility in this study. The increasingly used ultra-high strength structural steel S960 in industrial sectors was selected for investigation here. The results indicate that the calculated longitudinal residual stress applying the moving heat source and thermal cycle method is almost the same in and near the weld, while that is quite different mainly in the base metal directly under the weld area for UHSS. The predicted transverse residual stress using the thermal cycle method and moving heat source is significantly different, especially for the transforming UHSS. Although the thermal cycle method can obviously reduce the computing time, the moving heat source gives much better agreement with experimental results than the thermal cycle method in the assessment of welding residual stresses (WRS) overall in UHSS thick plates. Thus, the thermal cycle method is not reliable to predict WRS in thick structures made of UHSS. Furthermore, it is not recommended to use the thermal cycle method in numerical welding simulation for UHSS thin-walled structures.