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激光偏束焊对铌/钢接头组织及性能的影响

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

  • 摘要: 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.

     

    Abstract: 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.

     

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