Improvement of laser welding quality of Ti6Al4V alloy via experimental and predictive numerical modeling with the introduction of interface gap

This presentation reports an experimental and numerical study involving examination of the effects of processing parameters and interfacial gap in the range of 0-0.3 mm on the weld strength and weld appearance of lap welds produced by laser welding. Ti-6Al-4V alloy joints were welded using an IPG YLR-1000 fiber laser by varying laser power and scanning speed. The resultant weld joint depth and width were characterized experimentally and by numerical modeling. In addition, lap welding was carried out with the introduction of interface gap to determine its effects on the weld joint strength. The weld joint strengths were mechanically tested by both tensile shear and T-peel testing. Simulation of the welding process by a multi-physics model predicted hardness and the resultant phase that matched the experimental results closely and provided a further insight into the effects of welding parameters and interface gap. The test results indicate that an adequate amount of interface gap significantly improves weld strength and surface appearance for Ti-6Al-4V alloy. In addition, it is shown that porosity formation in laser welding of Ti-6Al-4V alloy can be mitigated by adding an optimal interface gap.