低能量激光冲击强化马氏体不锈钢的有限元模拟研究

The Finite Element Method Simulation on the Low-Energy Laser Shock Peening in Martensitic Stainless Steel

由于可用光纤远程传输的特性,低能量激光冲击强化工艺在大型零部件的在线冲击强化及延寿领域拥有潜在的应用空间。以汽轮机低压缸叶片AISI 420马氏体不锈钢为研究对象,通过有限元模拟低能量激光冲击强化过程及计算残余压应力场。采用Abaqus显式动力学分析,模拟激光冲击过程中能量和von Mises应力随时间的变化;基于Johnson-Cook金属材料塑性流变本构模型,计算残余应力场,并对比分析了脉冲时间、冲击次数及脉冲峰值压力对残余压应力分布和塑性变形表层深度的影响。结果显示,低能量激光冲击强化可获得与高能量参数近似大小的残余压应力,并与试验结果保持较好一致性。

Due to the feature of remote transmission by optical fiber,laser shocking peening with low pulse energy has a wide potential application in the field of on-site strengthening and life extension for large-sized mechanical components.In this work,finite element method was employed for the simulation of the laser shocking dynamic procedure and for the analysis of the static residual stress field in AISI 420 martensitic stainless steel,a typical material for the last-stage of steam turbine blades.Using Abaqus/Explicit dynamics,temporal distribution of the laser shock energy and von Mises stress were analyzed.Based on the Johnson-Cook plastic flow constitutive model,the residual stress and plastically-affected depth were comprehensively analyzed with parameters of pulse time,shot times,and peak pressure.The results indicated that laser shocking with low pulse energy has similar effect in terms of residual stress distribution with that obtained from high pulse energy.This trend also complied wellwithpublished experimental data.