Influence of the parameters of welding procedure on mechanical properties of laser welded SS/Nb joint

The influence law of the parameters of welding procedure on the tensile strength of laser welded stainless steel/niobium joint was studied by the orthogonal experiment. The results show that the tensile strength of joint decreased with the increase of welding speed, the strength of joint gradually rose with the laser beam moving from niobium to steel, and the influence of laser power on the strength of joint is very little. Among the three parameters of welding procedure, the influence of welding speed on the strength of joint is the largest, subsequently followed by the beam offset, and the influence of laser power on the strength of joint is minimum. The welding method of low welding speed and beam-offset to steel can improve the tensile strength of welded joint. The weld zone mainly consists of the IMC zone on the niobium side, the dendrite zone at the weld center and the dendrite zone on the steel side. The microstructure of joint mainly consists of plenty of γ austenite phase and a certain amount of Fe₂Nb with little δ ferrite phase. The forming of Fe-Nb intermetallic compounds is the main reason for reducing the strength of joint.