Simulation and Validation of Welding Residual Stresses Based on Non‐Linear Mixed Hardening Model

Abstract

This study contributes to Phase 2 of the Task Group 1 round robin in the NeT European Network. To obtain better prediction results, in the thermal analysis, two significant changes are used. The welding efficiency, η, is fixed at 75%, and the weld bead fusion boundary profiles are based upon macrographs taken from welded specimens, which have been destructively examined. In the subsequent mechanical simulation, a non‐linear kinematic or mixed isotropic–kinematic hardening model should be employed, and a progressive annealing scheme or explicit consideration of visco‐plastic or creep effects should be implemented to handle high‐temperature inelastic strains and reduce stress discontinuities. In this study, an uncoupled 3D thermal and mechanical analysis was carried out using the software code SYSWELD. In the thermal simulation, a two‐offset‐double‐ellipsoid heat source model was developed, and the parameters were fitted using the heat source fitting tool. Power intensity was applied to simulate 1‐s dwelling time at the weld start end. Offset distances between two double ellipsoids were adjusted to obtain the weld bead transverse fusion boundary profiles at different positions. Predicted temperatures were compared with the measured data by thermocouples on the test pieces. In the mechanical analysis, a new material constitutive model, non‐linear mixed hardening model, was developed. Tension–compression cyclic tests were simulated at different temperatures using three different material hardening models (isotropic hardening model, kinematic hardening model and non‐linear mixed isotropic–kinematic hardening model), and the predicted cyclic stress–strain curves were compared with the measured data. Effects of three different hardening models on the welding residual stresses were studied. Compared with the measured data, the optimum material hardening model was confirmed.

Thermomechanical Modeling of Welding and Galvanizing a Steel Beam Connection Detail to Examine Susceptibility to Cracking

“…Linear kinematic hardening was utilized to capture material behavior during welding [12]. The selection of a hardening model is an important choice for this type of analysis, and it has been discussed extensively in the literature [13][14][15][16][17][18][19]. Although the use of a combined model of kinematic and isotropic hardening would be preferable, obtaining the experimental data to calibrate it is extremely difficult because of the effects that temperature has on the mechanical properties of the steel.…”

Finite element simulation of butt welded 2·25Cr–1·6W steel pipe incorporating bainite phase transformation

“…Therefore, the heat transfer in the liquid pool was dominated by the transverse conduction. 27 The thermal effects due to solidification are modelled by considering the latent heat for fusion. The value of the latent heat is 270 J g 21 .…”

“…It meant that it was a rapidly travelling heat source. Therefore, the heat transfer in the liquid pool was dominated by the transverse conduction 27…”

Accurate Prediction of Welding Stress Evolution by Considering Improved Phase Transformation Model

“…In the simulation, a mixed hardening model based on Armstrong-Frederick hardening model 12) was used to describe the strain hardening of Weldox960. The mixed parameter, which defines the proportion of isotropic hardening model, is set at 30% and the stress-strain curves at room temperature obtained by the experiment and simulation are shown in Fig.…”