利用激光作为热源可对发生热应力变形的板材进行矫形, 对于发生热变形的中厚板材, 其内部不可避免的会存在初始残余应力。为研究初始残余应力对板材激光热矫形过程中应力场的影响, 基于ANSYS有限元分析平台对板厚为8 mm的高强钢Q345板材热变形的激光热矫形应力应变场进行了数值模拟分析。分析结果表明, 上表面初始残余拉应力较大时, 在加热过程中加热区域会首先发生一定程度的拉应变。相同变形及矫形工艺条件下, 初始残余应力存在情况下的矫形量小于不考虑初始残余应力情况下的矫形量, 下表面残余拉应力对板材变形过程具有阻碍作用。对矫形前后板材表面应力分布变化进行分析, 认为上表面激光扫描区域的初始残余应力对最终残余应力水平影响较小, 而下表面的初始残余应力水平会影响其最终应力的分布情况。

Laser beam can be employed as heat source to correct the thermal stress deformation of sheet metal. For medium thickness sheet metal which deformed under the thermal stress, there will be inevitable initial residual stress. In order to research the effect of initial residual stress on the stress field of laser thermal correction process, stress-strain field during the laser thermal correction of high strength steel Q345 plate with 8 mm thickness was simulated based on the finite element analysis platform of ANSYS. The analysis results show that tensile strain appears at the beginning of heating process when high residual tensile stress exists on the upper surface. And under the same deformation and process parameters, correction of deformation with initial residual stress is less than that without initial residual stress. The residual tensile stress on the lower surface has an impediment to the deformation process of the sheet metal. Comparison of stress distribution before and after correction was analyzed. It is considered that the initial residual stress of the upper surface laser scanning area has little effect on the final stress level, and the initial residual stress of the lower surface affects the final stress distribution.