An improved 3 D heat and mass transfer model was developed to study the effects of interface conditions during modelling of laser dissimilar welding. In detail, the interface conditions consist of the physical processes at gas/liquid surface (e.g. free surface deformation and optical absorptance), substrate interface (e.g. mixture properties in liquid phase and thermal contact condition) and solid/liquid interface (e.g. fusion line). Their effects on heat and mass transfer are numerically and experimentally analyzed, which are all non-negligible in the welding modelling. In conclusion, free surface deformation influences convection flow and should be considered in the situation of micro-welding and high energy-input welding. Besides, the energy transfer between laser and substrate is more reasonably described by the optical absorptance expressed in polynomial function. The mass transfer induced variation of mixture properties is well described by the method based on time-dependent mixture fraction. Thermal resistance between clamp and substrate should be considered in the modelling of temperature field on macroscale. The joint conductance at substrate interface could be neglected when modelling heat and mass transfer inside the melt pool, while it should be calculated in the simulation of temperature distribution based on the mechanism of heat conduction. The obtained results in this paper provide a vital insight into the interface conditions in laser dissimilar welding process.

开发了一种改进的 3D 传热和传质模型，以研究在激光异种焊接建模过程中界面条件的影响。详细地说，界面条件包括气/液表面的物理过程（如自由表面变形和光吸收率）、基体界面（如液相中的混合物性质和热接触条件）和固/液界面（如熔合线） . 它们对传热和传质的影响进行了数值和实验分析，这些在焊接建模中都是不可忽略的。综上所述，自由表面变形影响对流流动，在微焊接和高能量输入焊接的情况下应予以考虑。除了，用多项式函数表示的光吸收率可以更合理地描述激光和衬底之间的能量转移。基于时间相关混合物分数的方法很好地描述了传质引起的混合物性质的变化。在宏观温度场建模中应考虑夹具和基板之间的热阻。在模拟熔池内部的传热传质时，基体界面处的联合电导可以忽略，而在基于热传导机制的温度分布模拟中应计算。本文获得的结果提供了对激光异种焊接过程中界面条件的重要洞察。基于时间相关混合物分数的方法很好地描述了传质引起的混合物性质的变化。在宏观温度场建模中应考虑夹具和基板之间的热阻。在模拟熔池内部的传热传质时，基体界面处的联合电导可以忽略，而在基于热传导机制的温度分布模拟中应计算。本文获得的结果提供了对激光异种焊接过程中界面条件的重要洞察。基于时间相关混合物分数的方法很好地描述了传质引起的混合物性质的变化。在宏观温度场建模中应考虑夹具和基板之间的热阻。在模拟熔池内部的传热传质时，基体界面处的联合电导可以忽略，而在基于热传导机制的温度分布模拟中应计算。本文获得的结果提供了对激光异种焊接过程中界面条件的重要洞察。在模拟熔池内部的传热传质时，基体界面处的联合电导可以忽略，而在基于热传导机制的温度分布模拟中应计算。本文获得的结果提供了对激光异种焊接过程中界面条件的重要洞察。在模拟熔池内部的传热传质时，基体界面处的联合电导可以忽略，而在基于热传导机制的温度分布模拟中应计算。本文获得的结果提供了对激光异种焊接过程中界面条件的重要洞察。