选择性激光熔化成形温度场模拟与分析

Finite element simulation and analysis of the temperature field in selective laser melting process

在316L不锈钢的选择性激光熔化(SLM)三维成形过程模拟中,针对目前普遍采用单层热源加载进行模拟的局限性,采用ABAQUS软件建立了一个三维多层有限元模型来解决此问题。主要研究了在成形过程中,激光功率和扫描速率对粉床热行为的影响,在软件子程序中考虑了材料的粉末-液态-实体状态变化、相变潜热的影响,同时实现多层铺粉以及多层热源的加载。模拟结果表明:多层扫描中,随着扫描时间的增加,单层熔池的温度越来越高,熔池三维尺寸也逐渐增加,第二层比第一层粉床中心位置处的温度增加0.04%,熔池的宽和高分别增加1.33%、29%,第三层比第二层粉床中心位置处的温度增加0.02%,熔池宽和高分别增加1.35%、25.8%;成形过程中,熔池前端的温度梯度较大,随着线性能量密度(LED)的增加,熔池的温度和三维尺寸也逐渐增加。功率比扫描速率对粉床热行为的影响大,能量密度的范围在1.5~2.5 J/cm时,成形件的质量较好。

In this paper,in view of the limitation of simulations using single-layer heat source,a three-dimensional multi-layer finite element model by ABAQUS is established to solve this problem in the selective laser melting（ SLM） three-dimensional forming progress simulation of 316 L stainless steel powder.This research mainly study the effect of laser power and scan speed on the thermal behavior in the forming process,at the same time,the influence of powder-liquid-solid state change and the latent heat of phase change is considered into the simulation and spreading the powder layer by layer and loading the multilayer heat source using subroutine.The simulation results show that the temperature and dimensions of the singer-layer molten pool are increasing gradually with the increase of the scan time in the multi-layer scanning.The temperature at the center of the second layer is 0.04%,higher than the first layer,and the width and height of the pool increases by 1.33% and 29% respectively.Compared to the center of the second layer,the temperature of the third layer increased by 0.02% and width and height of the pool increases by 1.35% and 25.8% respectively.As the line energy density（ LED） increases,the temperature gradient of the front molten pool is bigger than the back end during forming progress,and the temperature and the dimensions of the molten pool is increasing.The power has a greater effect on the thermal behavior of the powder bed than the scanning rate,and when the energy density is in the range of1.5 ~ 2.5 J/cm,the quality of the forming part is better.