纳秒脉冲激光去除铝合金表面氧化膜数值模拟与试验研究
Numerical Simulation and Experimental Study of Nanosecond Pulsed Laser Removal of Oxide Film on Aluminum Alloy Surface

采用纳秒脉冲激光开展了7075铝合金表面5 μm厚氧化层的清洗研究。通过仿真模拟软件建立三维移动纳秒脉冲激光清洗7075铝合金表面氧化层的有限元模型，分析不同激光参数对氧化层表面的温度场分布的影响。分析了激光清洗试样表面的微观形貌，探讨了不同激光参数下的除氧化层效果以及基材表面的损伤情况。试验结果表明：当激光功率为34 W，试样表面的氧化层被完全去除，且粗糙度最低，基材表面未发生熔化；在该参数下清洗后试样表面氧元素最低，说明此参数为清洗阈值；去除量随功率增加而增加，与模拟结果相符；在激光功率为34 W的激光参数下除氧化层后，基材表面的硬度为432 HL，大于基材硬度，说明发生了激光表面硬化。
A nanosecond pulsed laser was used to carry out a study on the cleaning of a 5 μm thick oxide layer on the surface of 7075 aluminum alloy. A finite element model of the oxide layer on the surface of 7075 aluminum alloy cleaned by a three-dimensional moving nanosecond pulsed laser was established by simulation software to analyze the influence of different laser parameters on the temperature field distribution on the surface of the oxide layer. The microscopic morphology of the laser-cleaned specimen surface was analyzed, and the effect of removing the oxide layer and the damage to the substrate surface under different laser parameters were discussed. The test results show that: when the laser power is 34 W, the oxide layer on the surface of the specimen is completely removed, the roughness is the lowest, and the surface of the substrate is not melted; the oxygen element on the surface of the specimen is the lowest after the cleaning under this parameter, which indicates that this parameter is the threshold of the cleaning; the amount of the removal increases with the increase of the power, which is by the simulation results; the hardness on the surface of the substrate after removing the oxide layer under the laser parameter of the laser power is 34 W, which is 432 HL, greater than that of the substrate. 432 HL, which is greater than the hardness of the substrate, indicating that laser surface hardening has occurred.