Study on mechanical properties in the laser spot center of Fe-Ni elastic alloy induced by laser shock processing
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摘要: 为了研究激光冲击金属材料后,光斑中心区域材料力学性能异化现象,采用钕玻璃脉冲激光器产生的高能脉冲激光冲击强化型Fe-Ni恒弹合金(Ni42CrTiAl)材料。冲击后采用X射线应力仪对恒弹合金试样冲击区域表面进行了X射线衍射分析,测试了冲击区域残余应力分布情况。结果表明,在试样冲击区域产生了很高的残余压应力,且在光斑中心区域,残余应力值要略小于中心周围区域,出现了力学性能反弹现象。采用有限元模拟软件对冲击试验进行有限元模拟,进一步研究冲击诱导的残余应力分布情况;得到冲击区域有很高的残余压应力分布,且光斑中心区域的残余应力值小于其周围区域,模拟结果与测量结果一致。从冲击波运动、反射与逆向作用角度,探索了冲击区域中心出现的材料力学性能反弹现象的形成机理。这一结果对优化激光冲击强化过程和激光参量的选择是有帮助的。Abstract: In order to study the rebound phenomenon of mechanical properties in the spot center of metallic material induced by laser shock processing,Ni42CrTiAl,a Fe-Ni elastic alloy material,was processed by high-energy neodymium glass pulse laser.Then the distribution of the residual stress on the elastic alloy surface was tested with an X-ray strain gauge.The results showed that there was a high distribution of residual compressive stress in the shocked region and there was a rebound phenomenon of mechanical properties in the spot center region where the residual stress values slightly less than its surrounding area.And then for the purpose of further studying the distribution of the residual stress induced by laser shock processing,the finite elementsimulation software was introduced to simulate the shocking experiment.The simulation results showed that there was also a high distribution of residual compressive stress in the shocked region and a rebound phenomenon of mechanical properties in the spot center region.The simulation results are in good agreement with the measurement.Finally the formation mechanism of rebound phenomenon of the material mechanical properties in the center region was explored from the angle of the movement,the reflection and the reverse effect of the shock wave.This study result is benefit to optimize the process of the laser shock processing and laser parameter selection.
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