Experimental and FEM study of Ti-containing TWIP steel weldability

The mechanical and microstructural effects induced by high and low heat input of autogenous Gas Tungsten Arc Welding (GTAW) process in Fe-22Mn-1.8Al-1.2Si-0.57C TWIP steel microalloyed with titanium (TWIP-Ti) were evaluated through weld experiments. Different butt joints preparations in TWIP-Ti steel 5.8 mm thickness plates were used. A Finite Element (FE) model was applied to evaluate the deformation during welding process. The peak temperatures estimated numerically by the FE model were correlated with microhardness measurements carried out in high and low heat input welds. The lack of segregation of Mn and C at the melting zone interface contributed to avoid the hot-cracking in the welded joints at high and low heat input. The heterogeneous grain size microstructure in the welded specimens was affected by the heat input, which was correlated with the heat affected zone hardness measurements. An increase in both yield strength and ultimate tensile strength was measured in the low heat input weld as a result of the lack of hot cracking in the FZ-HAZ interface and the heterogeneous grain size distribution.