Abstract:The superplasticity of Ti-6Al-4V butt-welded plates by laser beam welding (LBW) was studied in virtue of hot tensile tests and superplastic bulging tests. Furthermore, microstructural evolution of weld metal upon superplastic forming was systematically analyzed via metallographical tests and scanning electron microscope (SEM). The relation between the microstructure of weld metal and its superplastic ability was discussed. The experimental results show that Ti-6Al-4V butt-welded plates by LBW possess superplasticity. The maximum elongation is up to 154% and the maximum bulge height can be up to 1.81 times the internal radius of the female die. There is an optimum value of the bulge height for bulging gas pressure.

Key words: superplastic forming; Ti-6Al-4V; laser beam welding