【摘要】 超快激光加工金属过程中，金属表面相变引发的熔体流动对加工质量具有显著影响。研究采用双温度模型耦合流体动力学的方法，模拟研究了皮秒激光作用下不锈钢表面的温度场、熔体流动特性及形貌演变，并分析了激光能量、激光移动速度等工艺参数对烧蚀效应的影响。结果表明：熔体流动显著影响烧蚀效应。相比于不考虑熔体流动的传统模型，考虑熔体流动的模拟结果与实验数据吻合良好，平均相对误差仅为7.5%，预测精度得到了显著提升。熔体流动主要受反冲压力与热毛细力的作用，并决定了最终的熔池形貌。在移动激光多脉冲作用下，熔体流动会导致中间凸起结构的形成。此外，随激光能量从1J/cm~2增至5J/cm~2，烧蚀坑深度由8.2nm增至34.6nm；激光移动速度从0.15μm/ps提升至0.25μm/ps时，热影响区宽度增加了约30%。研究结果为优化激光加工参数和提升微纳结构加工质量提供了理论依据。更多还原

【Abstract】 Ultrafast laser processing of metals induces surface phase change and melt flow, significantly impacting processing quality. A numerical model coupling the two-temperature model with fluid dynamics was developed to investigate the transient temperature field, melt flow, and morphology evolution of stainless steel under picosecond laser irradiation. The influence of laser fluence and moving speed on ablation characteristics was systematically evaluated. The results indicate that melt flow is critical to the ablation effect. Compared with traditional models neglecting hydrodynamics, the simulation results considering melt flow show good agreement with experimental data, with an average relative error of only 7.5%, indicating a significant improvement in prediction accuracy. The melt flow is primarily driven by recoil pressure and thermocapillary forces, which predominantly determine the final melt pool morphology. For moving multi-pulse processing, the melt flow leads to a central peak. Additionally, as the laser fluence increases from 1 J/cm~2 to 5 J/cm~2, the ablation depth grows from 8.2 nm to 34.6 nm. Increasing the moving speed from 0.15 μm/ps to 0.25 μm/ps causes an approximately 30% expansion in the width of the heat-affected zone. These findings provide valuable insights for optimizing ultrafast laser processing parameters and improving micro/nano-scale surface fabrication quality.更多还原