Microstructure and tensile properties of laser welded dissimilar Ti-22Al-27Nb and TA15 joints

The laser weldability of dissimilar Ti-22Al-27Nb and TA15 joints was investigated. Some layered textures in the fusion zone were characterized. The heat-affected zone of TA15 was divided into two regions based on the phase compositions: β + α′, β + α′ + α, with increasing distance to the fusion line. Similarly, three different regions in the heat-affected zone of Ti-22Al-27Nb were identified: B2, B2 + α2, and B2 + α2 + O. The fusion zone was composed of B2 + α′ dual phases, resulting from the chemical compositions of the fusion zone and rapid cooling rate of the laser welding process. Following tensile tests, the failure occurred in the weld at room temperature, while in the TA15 alloy at 650 °C. The fracture surface was examined, revealing features of quasi-cleavage fracture at room temperature and ductile fracture at 650 °C.