基于激光重熔的SLM成形316L不锈钢温度场仿真及工艺优化

Temperature Field Simulation and Process Optimization of SLM Forming of 316L Stainless Steel Based on Laser Remelting

SLM成形过程中激光重熔可改善冶金质量和提高性能,但是目前激光重熔对温度场的影响尚不清楚。本工作利用有限元方法建立316L不锈钢模型,对比未重熔与激光重熔的温度场特征,分析不同重熔工艺参数下的温度结果和不同重熔工艺参数下所制备样品的致密度和孔隙尺寸。结果表明,激光重熔有较好的预热效果,单层成形最低温度提高了约69%,多层成形因热量扩散影响预热效果仅将温度提高10%。激光重熔工艺对激光第一次扫描的最高温度没有影响,但可提高第二次扫描的温度。重熔激光能量密度从29 J/m升至117 J/m,最高温度上升了36.40%,最低温度上升了12%。致密度的改善不明显,但孔隙尺寸有明显的减小。当激光重熔能量密度为50 J/m时,致密度高达99.95%,孔隙的深度和宽度下降了64.9%和35.2%。

Laser remelting during SLM forming can improve metallurgical quality and performance,but the effect of laser remelting on the temperature field is still unclear.In this work,we use the finite element method to establish a model of 316L stainless steel,compare the temperature field characteristics of unremelted and remelted,and analyse the temperature results under different remelting process parameters;using prepared samples to analyse the density and pore size under different remelting process parameters.The results show that laser remelting has a good preheating effect,with a minimum temperature increase of approximately 69%for single-layer forming and only a 10%increase for multi-layer forming due to the effect of heat diffusion.The laser remelting process has no effect on the maximum temperature of the first laser scan,but can increase the temperature of the second scan.The remelting laser energy density increase from 29 to 117 J/m,with a maximum temperature increase of 36.40%and a minimum temperature increase of 12%.The improvement in density is not significant,but there is a significant reduction in pore size.When the laser remelting energy density is 50 J/m,the density is as high as 99.95%and the depth and width of the pores decreased by 64.9%and 35.2%.