通过控制CO2连续激光器的有关工艺参数,对LY12CZ铝合金进行了激光表面重熔,并对重熔后的试样进行了疲劳实验、疲劳断口分析、金相分析及显微硬度测试。研究结果表明,LY12CZ铝合金经过激光重熔后,疲劳寿命与未经激光处理试样相比无显著差异,疲劳断口显示疲劳裂纹源区出现在重熔区的表层,疲劳裂纹沿着柱状晶的晶界扩展,在基材处瞬断。激光重熔后表层金相组织明显细化,使得材料表层的显微硬度比基体硬度提高了40%。

Through controlling the related processing parameters of continuous wave CO2 laser, LY12CZ surface was remelted by laser and after remelting the fatigue test, fatigue fracture, microstructure and micro-hardness were analyzed. The result showed that there was no obvious difference between the fatigue life of specimen with and without laser remelting. The fatigue fracture indicated that the fatigue crack resource was at the surface of remelting region, and the crack extended along the grain boundary of the columnar crystal and broke suddenly in the substrate. After remelting, the grains at the surface were obviously fined, and the micro-hardness of the surface was improved by 40% in contrast to substrate.