IN718合金增材制造温度场仿真及微观组织分析

针对微观组织的调控相关问题,构建了IN718材料激光选区熔化(selective laser melting,SLM)温度场仿真的三维有限元模型,研究了激光功率和扫描速度对熔池温度场和凝固机理的影响,进而预测增材制造材料的微观组织,为微观组织的调控提供理论依据。首先分析了激光功率和扫描速度对熔池尺寸的影响,分析了不同工艺参数下熔池温度场的变化;其次基于温度场的仿真结果,计算不同工艺参数下熔池固液界面处温度梯度和凝固速度的变化,分析凝固过程中柱状晶向等轴晶的转变条件,预测熔池不同深度上的微观组织。研究结果发现提高激光功率有利于等轴晶的形成,而扫描速度对等轴晶厚度占比影响不大,另外降低激光功率和提高扫描速度将促使形成的微观组织尺寸更细小。

Temperature Field Simulation and Microstructure Analysis of Additive Manufacturing Fabricated IN718

In this paper,a three-dimensional finite element model for the simulation of temperature field in selective laser melting(SLM)of IN718 material is established.The effects of laser power and scanning speed on the temperature field and solidification mechanism of molten pool are studied,and then the microstructure of additive manufacturing material is predicted,which provides a theoretical basis for the microstructure control.In this paper,the influence of laser power and scanning speed on the size of molten pool is analyzed,and the change of molten pool temperature field under different process parameters is analyzed.Then,based on the simulation results of temperature field,the changes of temperature gradient and solidification speed at the solid-liquid interface of molten pool under different process parameters were calculated,the transition conditions from columnar crystal to equiaxed crystal during solidification were analyzed,and the microstructure at different depths of molten pool was predicted.The result shows that increasing the laser power tend to form equiaxed crystal,while the scanning speed has little effect on the thickness ratio of equiaxed crystal.In addition,reducing the laser power and increasing the scan speed will result in a finer microstructure.