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本文在分析和实验的基础上,系统地阐述了在激光合金化过程中的一些基本特征。这包括激光合金化的传质和传热特征,激光作用下的合金熔池内的熔化时间的分布特征,激光合金化过程中的熔池表面特征及其凝固表面特征。研究结果表明,在激光加热作用过程中,合金熔池的传质和传热主要受由表面张力梯度引起的对流作用控制,而在激光加热作用停止之后,在熔池真空凝固开始之前,在合金熔池的边缘区域的传质和传热却主要由温度梯度引起的扩散作用所控制。另一方面,在激光合金化熔池内,各处的熔化时间是不一致的。在熔池表面(XOY 平面)的中心处,其熔化时间最长,其余各处的熔化时间较短,在熔池的边缘附近,其熔化时间最短,几乎为零值。最后,指出了凝固表面特征由材质的热物性,表面张力、润湿特性和激光合金化参数综合决定。
Based on the analysis and experiment, this paper systematically expounds some basic characteristics in laser alloying process. This includes the mass transfer and heat transfer characteristics of laser alloying, the distribution of melting time in the molten pool under laser action, the surface characteristics of the molten pool during laser alloying and the surface characteristics of the solidified surface. The results show that during laser heating, mass transfer and heat transfer of the alloy weld pool are mainly controlled by convection caused by the surface tension gradient. After the laser heating is stopped, before the vacuum solidification in the weld pool begins, The mass transfer and heat transfer in the edge of the pool are mainly controlled by the diffusion caused by the temperature gradient. On the other hand, in the laser alloyed molten pool, melting time is inconsistent everywhere. At the center of the pool surface (XOY plane), the melting time is the longest and the melting time is short everywhere, with the shortest melting time near the edge of the bath, which is almost zero. Finally, it is pointed out that the characteristics of the solidified surface are determined by the thermal physical properties, surface tension, wetting properties and laser alloying parameters of the material.