Influence of fiber laser cutting parameters on the subsequent laser welding of Ti6Al4V sheets

One approach to reduce the titanium alloy machining costs and extensive material usage is to join pieces obtained by Laser Beam Cutting (LBC) process. Cutting with fibre laser sources represents a promising tool in machining titanium alloy parts with subsequent welding requirements. Fibre lasers offer a great potential in improving the productivity of cutting phase with an acceptable edge quality, in particular when thin sheets are concerned. The paper investigates the effect of laser cutting parameters on the mechanical behavior of laser butt welded joints whose edges were obtained by laser cutting. In the first part of the experimental activity, investigation on the effect of cutting speed and assist gas pressure on Ti6Al4V 1mm thick sheets cut with fibre laser was carried out. At the same time laser welding process using a Nd:YAG laser was performed on sheets with cut edges generated by machining. Once the optimal welding condition was determined, the mechanical characterization of Ti6Al4V sheets cut with fibre laser and then laser joined was performed. Tensile tests revealed that the shear gas pressure is the main parameter affecting the ultimate tensile strength because it is directly correlated to the quality of the cutting edge.