钛合金带热沉钨极氩弧焊中热沉作用

采用数值模拟和实验相结合的方法研究了钛合金TC4薄板常规及带热沉的钨极氩弧焊焊接过程中温度及应力应变的分布,考察了热沉对温度场和应力应变场的影响规律,探讨了使用该技术实现应力和变形控制的机理.结果表明:带热沉的钨极氩弧焊焊接过程中,紧随热源之后热沉急冷作用使得试件形成马鞍形温度场,而热沉作用部位温度最低.热沉作用部位的急冷收缩对周围金属产生拉伸作用,使得焊缝及近缝区金属升温过程中产生的压缩塑性应变减小,冷却过程中产生的拉伸塑性应变增大,接头中不协调应变减小,残余应力降低.实验测量与有限元模拟结果吻合良好,证实了采用热沉控制应力与变形的有效性和有限元模型的正确性.

Role of heat sink in gas tungsten arc welding with trailing spot heat sink for titanium alloy

The distribution of temperature, stress and strain of titanium alloy Ti-6Al-4V thin sheet were studied with numerical simulation and experiment during conventional gas tungsten arc welding and gas tungsten arc welding with trailing spot heat sink behind welding arc, also named dynamically controlled low stress no-distortion gas tungsten arc welding, the influences of heat sink on temperature, stress and strain fields were investigated, the stress and distortion controlling mechanism of dynamically controlled low stress no-distortion technique was discussed. The results show that, during dynamically controlled low stress no-distortion gas tungsten arc welding, the saddle shape temperature field is formed due to the intense cool effects of heat sink, there exists the lowest temperature in the heat sink applied region. High tensile action of metals is generated by sharp cooling of the heat sink applied region, which decreases the compressive plastic strains in heating process and increases the tensile plastic strains in cooling process within and near the weld. The incompatible strains in the joint decrease and the residual stresses reduce. The simulation results are in good agreement with the experimental results, which proves the effectiveness of DC-LSND technique and the validity of the finite element model.