Finite element simulation of the residual stress in butt-welded ferritic steel pipe considering the diffusional phase transformation effects

摘要

This work aims at developing a thermal-metallurgical-mechanical computational procedure based on ABAQUS code to predict welding residual stresses in multi-pass butt-welded 2.25Cr-1.6W steel pipes, considering the influence of the diffusional phase transformation. In the numerical simulations, the Johnson-Mehl-Avrami-Kolmogorov (J-M-A-K) equations are used to track the austenite-bainite transformation. Based on this model, a new numerical optimization method is developed to determine the parameters in the J-M-A-K equations. This methodology provides a more accurate global optimization to calculate the temperature dependence of austenite-bainite transformation volume fraction under various cooling rates, and sequentially to obtain the corresponding welding residual stresses in multi-pass butt-welded 2.25Cr-1.6W steel pipes. The simulation results reveal that the final welding residual stresses in 2.25Cr-1.6W steel pipes are significantly affected by both volumetric change and bainite transformation volume fraction. A comparison between experimental measurements and theoretical calculations is performed, and the results from those two methods agree well with each other. The effectiveness of the developed computational producer was confirmed.