AZ91镁合金激光冲击强化力学性能研究

Effects of laser shock processing on mechanical properties of AZ91 magnesium alloy

为了研究激光冲击强化对镁合金力学性能的影响以及不同激光冲击模式的效果,采用双束无叠加钕玻璃脉冲激光对AZ91镁合金进行冲击处理;冲击后在试样表面得到椭圆冲击斑,对光斑形貌和形状进行了观测分析,并与传统单点叠加冲击模式的结果对比。采用Triboindenter纳米压痕仪测试了冲击和未冲击区域的纳米硬度,得到测量值分别为1.59GPa和1.47GPa;采用X2350A型X射线应力衍射仪测试冲击区域残余应力分布情况,并用有限元软件ABAQUS对残余应力进行了数值模拟,得到实验测量和模拟结果在加载区域都有高达-120MPa左右的残余应力分布,且模拟结果与实验结果一致。结果表明,采用双束无叠加冲击模式可以提高冲击效率;激光冲击处理提高了镁合金的纳米硬度和力学性能,增强了其抗外物冲击损伤和抗疲劳性能。

In order to study the influence of laser shock processing （LSP） and different laser shock model on the mechanical properties of magnesium alloy, an AZ91 magnesium alloy specimen was processed with two beams of nonsuperimposed Nd：glass laser pulses. The surface morphology, with an oval spot distribution, was observed and analyzed after shock, and then the model was compared with the traditional model of single-point-superposition. The nano-hardness of the shocked and non-shocked region was measured with a triboindenter nano-indentation instrument, and the measured value was 1.59GPa and 1.47GPa respectively. The residual stress in the shocked region was measured with a X2350A X-ray strain instrument, and the stress was simulated by means of the finite element software ABAQUS. Both experimental and simulation results were in good agreement, and showed that there was high residual stress distribution, about - 120MPa in the shocked region. The results show that the non-superposition of dual-beam mode can improve the shock efficiency. The LSP can improve the nano-hardness and mechanical properties of magnesium alloy and enhance its resistance to foreign objects damages and antifatigue properties.