Process optimization of laser reflection-induced superimposition deep-penetration welding for titanium alloy sheet

A novel sheet metal laser deep-penetration welding method, namely laser reflection-induced superimposition welding, is presented to overcome the shortcomings of existing methods. Based on the orthogonal optimization experiment and single factor optimization experiment, the welding parameters of titanium alloy sheet reflection-induced superimposition welding is optimized with taking weld-morphological characteristics as evaluation indexes. The results show that welding speed has the greatest influence, followed by defocusing amount, and the influence of laser power is very small. With the decrease of welding speed, the cross-sectional morphologies of welds transformed from inverted V shape to near X shape, H shape, and Y shape. With the experiment conditions in this work, the optimized parameters of laser welding are 500 W laser power, 30 mm/s welding speed, -0.5 mm defocusing amount. The H-shaped weld whose weld width back to surface ratio almost equals to 1 can be obtained with the optimized parameters, and there is no pitting defect on the back of welds.