激光偏束焊对铌/钢接头组织及性能的影响

文中对铌/钢进行了激光焊接，当激光束直接作用于铌/钢接触面时，由于Nb-Fe金属间化合物Fe₂Nb的生成呈现连续分布的特点会使焊后接头发生断裂.针对该问题，采用激光偏束焊对铌/钢进行焊接，通过激光束偏钢侧来抑制铌的熔化量，进而减少接头中Fe₂Nb的生成.结果表明，通过采用激光偏束焊的方式可以较好地抑制接头开裂的问题.组织分析表明，焊后接头组织主要由γ奥氏体相与一定量的Fe₂Nb相及少量的δ铁素体组成.力学性能结果显示，断裂发生在接头Fe₂Nb金属间化合物层处，其抗拉强度为221 MPa，最高硬度出现在Fe₂Nb金属间化合物层约为1 143 HV.

Effects of beam-offset on microstructure and properties of laser welded Nb/304 SS joint

In this work, the Nb/304 SS joint was welded by laser welding. The joint fractured immediately due to continuously distributed Fe₂Nb intermetallic compounds when the laser was directed to the Nb/steel interface. In order to solve the problem, the laser beam-offset welding procedure was proposed. The amount of melted niobium was reduced by the laser offset effect. Finally, the formation of Fe₂Nb intermetallic compounds was controlled. The results showed that laser beam-offset welding was an ideal way to control the joint crack which occurred in laser centered welding condition. The joint microstructure was mainly consisted of γ austenite phase and a certain amount of Fe₂Nb intermetallic compounds with little δ ferrite phase. The tensile strength of the joint was 221 MPa, the fracture occurred in the Fe2Nb intermetallic compounds layer. The highest microhardness existed in Fe₂Nb intermetallic compounds layer with a value of 1 143 HV.