The effect of non-equilibrium solid state phase transformation on numerical simulation of welding temperature field is researched during keyhole mode laser welding of Ti6Al4V alloy. The simulation of the welding temperature field considering equilibrium phase transformation is obtained by means of the model of the heat transfer and fluid flow after the keyhole presetting. Based on the simulation considering equilibrium phase transformation, the simulation considering non-equilibrium phase transformation is modified, in terms of partitioning the regions and endowing the physical parameters considering non-equilibrium phase transformation. Compared with those considering equilibrium phase transformation in the horizontal planes, the temperature contours greater than or equal to 1300 K considering non-equilibrium phase transformation are elongated, while the temperature contours between 1100 K and 1300 K considering non-equilibrium phase transformation are shortened. The difference of the welding temperature fields considering equilibrium and non-equilibrium phase transformations basically emerges in the cooling stage. The temperature fields considering non-equilibrium phase transformation after modifying once and twice are almost the same, signifying that the simulation considering non-equilibrium phase transformation after modifying once is sufficient. The computational results considering non-equilibrium phase transformation agree well with the experimental ones in contrast with those considering equilibrium phase transformation, showing that the simulation considering non-equilibrium phase transformation after modifying once is reliable and satisfactory.

研究了Ti6Al4V合金小孔模式激光焊接过程中非平衡固态相变对焊接温度场数值模拟的影响。通过小孔预置后的传热和流体流动模型，得到了考虑平衡相变的焊接温度场模拟。在考虑平衡相变的模拟的基础上，对考虑非平衡相变的模拟进行了修改，在区域划分和赋予考虑非平衡相变的物理参数方面进行了修改。与考虑水平面平衡相变的那些相比，考虑非平衡相变的大于或等于1300 K的温度等值线被拉长，而考虑到非平衡相变的 1100 K 和 1300 K 之间的温度等值线被缩短。考虑平衡相变和非平衡相变的焊接温度场的差异基本上出现在冷却阶段。一次和两次改性后考虑非平衡相变的温度场几乎相同，说明考虑一次改性后非平衡相变的模拟就足够了。考虑非平衡相变的计算结果与考虑平衡相变的计算结果与实验结果吻合较好，表明考虑非平衡相变一次修正后的模拟是可靠且令人满意的。