焊接工艺参数对钢/铌激光焊接头性能的影响

采用正交试验法分析了焊接工艺参数对钢/铌激光焊接头抗拉强度的影响规律.结果表明，接头抗拉强度随着焊接速度的增大而降低；随着激光束从铌侧向钢侧偏移，接头强度逐渐升高；激光功率对接头强度的影响不大.在3个焊接工艺参数中，偏束距离对接头强度的影响最大，焊接速度次之，激光功率的影响最小.采用低焊接速度、向钢侧偏束的焊接方法可以提高焊接接头的抗拉强度.焊缝区主要包括铌侧的IMC区，焊缝中心的树枝晶区与钢侧的树枝晶区三个特征区.其组织由大量的γ奥氏体相与一定量的Fe₂Nb相及少量的δ铁素体相组成.铁-铌金属间化合物的生成是降低接头强度的主要原因.

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.