Comparative study on weldability of Ti-containing TWIP and AISI 304L austenitic steels through the autogenous-GTAW process

In this study, a pair of welds was made in austenitic stainless steel AISI 304L and the novel twinning-induced plasticity (TWIP) steel microalloyed with titanium. Microstructural characterization and mechanical assessment were conducted with the aim to compare the weldability of both materials. The weld joints were performed in two passes by means of the autogenous gas tungsten arc welding (GTAW) process. The operating parameters were defined with the aid of penetration depth predictions carried out by a finite element (FE) numerical model. The results indicated that the weldability of TWIP-Ti steel compared to that of the AISI 304L steel had some advantages as the lower extension of the heat affected zone (HAZ) and a lower mechanical properties loss with respect to the base material. The ferritic solidification mode towards the outer of the FZ in the AISI 304L steel avoided hot cracking in the HAZ. Conversely, the HAZ of TWIP-Ti steel did not present hot cracking despite the austenitic solidification mode. The higher thermal diffusivity of the TWIP-Ti steel had a positive effect in the HAZ conditions improvement, which in turn was correlated with the welding cooling rates and microstructural aspects through the FEM model.