Improved thermal FE numerical model/DoE based on the Taguchi method to estimate weld penetration/energy and non-metallic inclusions: a case study in Ti-containing TWIP steel butt joints

Abstract

In this research work, a finite element (FE) numerical analysis was conducted to study the welding thermal field. The finite element model (FEM) was improved by means of the optimal mesh element size using statistical analysis of a design of experiment (DoE) based on the Taguchi method. Through the improved FEM, numerical model were carried out estimations of the penetration depth, heat dissipation phenomenon, and thermal energy input. Then, FE numerical results were linked to Matlab®. The FEM-Matlab® approach proposed the application of thermal energy predictions to estimate welding critical zones extensions and their possible non-metallic inclusions. The FEM-MATLAB® approach was applied to a case study: twinning-induced plasticity steel microalloyed with titanium (TWIP-Ti) weldments. Welding experiments were performed with the autogenous Gas Tungsten Arc Welding (GTAW) process in 6.3-mm thickness plates. The weld samples were analyzed metallographically to measure welding critical regions extensions. Both austenitic grain size and non-metallic inclusions were in good agreement with numerical results. The weld bead obtained by means of the optimal process parameters estimated by the FEM-Matlab® approach achieved full penetration and showed better microstructural characteristics according to the numerical estimation.