激光冲击强化对AZ31镁合金力学性能和组织结构的影响

Effect of Laser Shock Processing on Mechanical Properties and Mesostructures of AZ31 Magnesium Alloy

为了研究激光冲击强化(LSP)对镁合金力学性能的影响,采用电子万能高温拉伸机和钕玻璃脉冲激光(波长1064 nm,脉冲宽度20 ns)研究AZ31镁合金薄板室温和300℃时拉伸应力-应变曲线和力学性能。结果表明,LSP提高了AZ31镁合金室温和高温抗拉强度,而冲击试样的最大热流变应力明显高于未冲击的试样,双面单次LSP导致室温力学性能降低,在激光冲击试样断口发现了沿次表层扩展的层裂现象。讨论和分析了残余压应力、细微结构、表面形貌和粗糙度对激光冲击镁合金力学性能的影响。

In order to study the effect of laser shock processing（LSP） on mechanical properties of magnesium alloy, the room and thermal（300 ℃） tensile stress-strain curves of AZ31 alloy sheets are investigated by using electronic universal high temperature tensile machine and Nd： glass laser with wavelength of 1064 nm and pulse width of 20 ns. The results show that the room and thermal tensile strength of AZ31 alloy are improved by LSP. The maximum thermal flow stress of laser shocked specimens is obviously higher than that of untreated. However, the double- sided single LSP results in the reduction of mechanical properties at room temperature. And the spallation phenomenon which extends along subsurface occurs on fracture of the shocked samples. Effect of the residual compressive stress, mesostructures, surface morphologies and roughness on mechanical properties of magnesium alloy by LSP are discussed and analyzed.