强激光直接辐照铝靶诱导残余应力的分布特性

Distribution Characteristic of Residual Stress in Aluminum Target Irradiated Directly by High Power Laser

为研究强激光直接辐照靶材诱导残余应力的分布特性,利用Nd∶YAG型激光器对7075铝合金试样在无吸收层和有吸收层的条件下分别进行了激光辐照试验,并对试验结果进行了对比。结果表明,激光直接辐照后的试样表面产生了重熔层和激光烧蚀斑点,试样表面分布的最大残余拉应力(TRS)为116.2 MPa,试样深度方向分布的残余应力为"拉应力-压应力(CRS)-拉应力",且深度方向最大残余压应力为153.6 MPa,显微硬度在深度方向的最大值为174.5 HV。有吸收层时,吸收层激光辐照处存在近似光斑大小的圆形烧蚀区域,去除吸收层后试样表面存在光滑的凹坑;试样表面分布的最大残余压应力为264.7 MPa,试样深度方向分布的残余应力为"压应力-拉应力",深度方向的最大残余压应力为258.3 MPa,显微硬度在深度方向的最大值为193.6 HV。

In order to investigate the distribution characteristic of residual stress in targets directly irradiated by high power laser, the experiments of laser irradiation on 7075 aluminum alloy samples under the condition with or without absorbing layers are respectively conducted by means of Nd： YAG laser, and the experimental results are compared. The results show that there are remelting layers and ablation spots on the sample surface after direct laser irradiation. The maximum tensile residual stress （TRS） distributed on the surface of samples reaches 116.2 MPa, the residual stress distrihution in the depth direction of the sample is TRS-compressive residual stress （CRS）-TRS, the maximum CRS in the depth direction is 153.6 MPa, and the maximum micro-hardness in the depth direction is 174.5 HV. When the absorbing layer is included, there is a circular ablation zone on the surface of the absorbing layer, and the smooth dent appears on the sample surface after the removal of the remaining absorbing layer. The maximum CRS distributed on the surface of samples is 264.7 MPa, the residual stress distribution in the depth direction of the sample is CRS-TRS, the maximum CRS in the depth direction is 258.3 MPa, and the maximum micro-hardness in the depth direction is 193.6 HV.