Development of thermo conductive analysis simulation in order to aid laser welding of dissimilar metals

在这项研究中，钢和铝合金被选为异种金属的组合。编制了边界元分析程序。通过分析，假设界面处发生固/液反应，得到了激光焊接条件。在边界元分析预测的条件下，对钢与铝合金的焊接接头进行了试验研究。接头界面处形成了Fe和Al之间的金属间化合物相。接头的强度由该金属间相控制，因为该相具有差的机械性能。即使在界面处存在脆性反应层的情况下，增加结合面积也可以提高接头的破坏载荷。根据边界元分析，改变接头形状和/或在焊接区设置接触垫可以控制界面温度分布，增加结合面积。在这种情况下，也通过边界元分析预测焊接条件。通过拉伸试验和界面处的横截面观察，确认了接头和粘结区的破坏载荷的增加。边界元模拟与界面状态的假设如上所述，也预测了结合区的大小。总之，本研究建立了异种金属激光焊接的计算机辅助方法，并证明了其有效性。

Steel and aluminum alloy were chosen as a combination of dissimilar metals in this study. Boundary element analysis program was developed. Laser welding condition was obtained by the analysis, assuming of solid state / liquid state reaction at the interface. A joint between steel and aluminum alloy was welded under the condition predicted by BEM analysis. Intermetallic phase between Fe and Al was formed at the interface of the joint. Strength of the joint was controlled by this intermetallic phase, because this phase has poor mechanical properties. Even if brittle reaction layer exists at the interface, increase of bonded area could be a way to improve failure load of the joint. According to BEM analysis, change of shape of joint part and/or applying contact pad at welding zone can control temperature distribution at the interface and increase bonded area. In this case also, the welding condition was predicted by BEM analysis. Increase of failure load of joint and bonded area was recognized by tensile test and cross-sectional observation at the interface. The BEM simulation with assumption of interface state as mentioned above also predicted the size of bonded area. In conclusion, the computer aiding method for dissimilar metals laser welding was developed and its availability was shown in this study.