激光冲击次数对TA15微观组织和硬度的影响

采用脉冲能量20 J的调Q掺钕玻璃激光对钛合金TA15进行不同次数的激光冲击强化.结果表明，激光冲击强化使材料表面产生微塑性变形，形成致密的微凹坑，导致晶粒细化，并且随冲击次数的增加，其微凹坑的深度增加；但当冲击次数超过2次后，深度便不再增加.所以试验中的最高冲击次数为2次，而且在冲击次数为2次以内，材料位错密度也随冲击次数的增加而增加，并发生塞积、增殖、缠结等现象.表征在硬度方面，由于上述微观组织的变化，材料的硬度提高.随着冲击次数增加，材料的硬度增加并且激光冲击强化的影响层深度也随之增加.

Influence of laser shock peening times on microstructure and hardness of TA15 titanium alloy

Q-switched Nd glass laser with 20 J energy was used to shock TA15 titanium alloy in different times. Results show that laser shock peening (LSP) can produce micro plastic deformation, form dense micro pits and refine the grain size. When the number of impact times increases, the depth of the micro pits increases, but after the impact times is more than twice, the depth of the pits will stop increasing, so the highest impact times is twice in this experiment. Under the impact times of twice, the dislocation density is increasing with the increase of impact times. In the process, the dislocation will pile up, snarl, and proliferate. The hardness of the material increases because of the variation of microstructure above. The surface hardness and the depth of affected layers increase due to the increase of the shock times.