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Ti6Al4V合金在毫秒激光打孔过程中,沿孔壁会形成严重影响成品性能的重铸层。考虑熔体受到的热学和力学等方面的影响,基于修改的流体力学方程和改进的水平集法,建立了激光打孔的固/液/气三相二维数值计算模型,在单脉冲能量为3J的条件下,对不同脉宽参数的激光打孔进行数值研究。运用后处理技术提取了打孔过程中重铸层的温度场、流场和厚度分布情况。结果表明,蒸发和喷溅是熔体排除的主要方式,重铸层是在热-力耦合作用下形成的。重铸层的厚度随激光脉宽的增大而增加,并呈现从孔口到孔底逐渐变薄的特征。
Ti6Al4V alloy in the millisecond laser drilling process along the hole wall will form a serious impact on the performance of the recast layer. Considering the influence of the thermal and mechanical properties of the melt, a two-dimensional numerical model of solid / liquid / gas three-phase laser drilling was established based on the modified hydrodynamics equation and the improved level set method. 3J under the conditions of different pulse width parameters of laser drilling numerical study. The post-processing technique was used to extract the temperature field, flow field and thickness distribution of recast layer during drilling. The results show that evaporation and splashing are the main ways to eliminate the melt, and the recast layer is formed under thermo-mechanical coupling. The thickness of recast layer increases with the increase of laser pulse width, and shows the feature of thinning gradually from the orifice to the bottom of the hole.