针对基板预变形下304L不锈钢的激光立体成形(LSF),建立了3D参数化模型,对激光成形过程中瞬时应力场以及残余应力场和基板最终形状进行了瞬态热弹塑性有限元分析。通过模拟发现,基板预变形可以有效缓解激光立体成形过程中基板的变形,提高成形后基板的平整度,从而有效避免基板翘曲导致的成形件精度降低甚至成形失败等问题。对于多道单层的激光熔覆沉积,基板上表面的残余拉应力σX分布在激光熔覆的最后2-3道处,而残余压应力σX分布在先熔覆的2-3道处,中间为过渡区。经预变形,激光熔覆沉积后处于基板上表面初始应力区的残余应力σX比无预变形要大,而远离初始应力区的残余应力σX比无预变形要小。

A 3D parametric model was developed to perform the transient thermo-mechanical finite element method (FEM) simulation on the transient stress field as well as the residual stress field and the final shape of substrate for the laser solid forming (LSF) of 304L stainless steel with the pre-deformation substrate. The results showed that the pre-deformation of the substrate can effectively alleviate the warping of substrate during LSF,and improve the roughness of the substrate after LSF,which will be in favor of avoiding the decrease of the forming precision and even the processing failure which caused by the distortion of the substrate during LSF. For multi-pass single-layer laser deposition,it is found that the residual tensile stress σX lied in the final 2-3 passes,and the residual compressed stress σX lied in the first 2-3 passes. The residual stress σX which is in the initial stress zone on the top surface of pre-deformation substrate is higher than that of the substrate without pre-deformation after LSF,but the residual stress σX in the region far away from the initial stress zone on the top surface of pre-deformation substrate is low.