3-Dimensional heat transfer modeling for laser powder-bed fusion additive manufacturing with volumetric heat sources based on varied thermal conductivity and absorptivity

In this article, a 3-dimensional heat-transfer finite element model for Laser Powder-Bed Fusion (LPBF) was developed for accurately predicting melt pool dimensions and surface features. The sole deployment of trial-anderror experiments for arriving at optimal process parameters is very costly and time-consuming, thus the developed model can be used to reduce the process/material development costs. A literature review of heat source models was presented. Eight commonly used heat source models are evaluated and compared. All of their simulated depths are smaller than the experimental result, which may be due to the melt pool convection and inconstant laser absorptivity in the reality during the experiment. In order to enable the numerical model to predict melt pool dimensions for different combinations of process parameters, a novel model including expressions of varied anisotropically enhanced thermal conductivity and varied laser absorptivity is proposed and verified by both the melt pool dimensions and track surface morphology. It is found that the heat source expressions can be linear while causing the simulation results to be in better agreement with both experimental melt pool dimensions and track surface morphology.

在本文中，建立了一个用于激光粉末床熔融（LPBF）的三维传热有限元模型，以准确预测熔池尺寸和表面特征。仅仅通过反复试验来确定最佳工艺参数是非常昂贵且耗时的，因此所建立的模型可用于降低工艺/材料开发成本。对热源模型进行了文献综述。对八种常用的热源模型进行了评估和比较。它们模拟的深度都小于实验结果，这可能是由于实验过程中实际存在的熔池对流和激光吸收率不稳定。为了使数值模型能够预测不同工艺参数组合下的熔池尺寸，提出了一种包含各向异性增强热导率变化和激光吸收率变化表达式的新模型，并通过熔池尺寸和熔道表面形貌进行了验证。研究发现，热源表达式可以是线性的，同时使模拟结果与实验熔池尺寸和熔道表面形貌更好地吻合。