Shen Hongyao, Yan Jinwen, Niu Xiaomiao
The State Key Laboratory of Fluid Power and Mechatronic Systems, College of Mechanical Engineering, Zhejiang University, Hangzhou 310027, China.
Key Laboratory of 3D Printing Process and Equipment of Zhejiang Province, College of Mechanical Engineering, Zhejiang University, Hangzhou 310027, China.
Materials (Basel). 2020 Sep 18;13(18):4157. doi: 10.3390/ma13184157.
A three dimensional finite element model (FEM) was established to simulate the temperature distribution, flow activity, and deformation of the melt pool of selective laser melting (SLM) AZ91D magnesium alloy powder. The latent heat in phase transition, Marangoni effect, and the movement of laser beam power with a Gaussian energy distribution were taken into account. The influence of the applied linear laser power on temperature distribution, flow field, and the melt-pool dimensions and shape, as well as resultant densification activity, was investigated and is discussed in this paper. Large temperature gradients and high cooling rates were observed during the process. A violent flow occurred in the melt pool, and the divergent flow makes the melt pool wider and longer but shallower. With the increase of laser power, the melt pool's size increases, but the shape becomes longer and narrower. The width of the melt pool in single-scan experiment is acquired, which is in good agreement with the results predicted by the simulation (with error of 1.49%). This FE model provides an intuitive understanding of the complex physical phenomena that occur during SLM process of AZ91D magnesium alloy. It can help to select the optimal parameters to improve the quality of final parts and reduce the cost of experimental research.
建立了三维有限元模型（FEM），以模拟选择性激光熔化（SLM）AZ91D镁合金粉末熔池的温度分布、流动活性和变形。考虑了相变潜热、马兰戈尼效应以及具有高斯能量分布的激光束功率的移动。本文研究并讨论了施加的线性激光功率对温度分布、流场、熔池尺寸和形状以及由此产生的致密化活性的影响。在此过程中观察到较大的温度梯度和高冷却速率。熔池中发生剧烈流动，发散流使熔池更宽更长但更浅。随着激光功率的增加，熔池尺寸增大，但形状变得更长更窄。获得了单扫描实验中熔池的宽度，与模拟预测结果吻合良好（误差为1.49%）。该有限元模型为AZ91D镁合金SLM过程中发生的复杂物理现象提供了直观的理解。它有助于选择最佳参数以提高最终零件的质量并降低实验研究成本。
