In this paper, a novel hybrid heat source model is developed considering the different absorption mechanisms for porous and dense state materials, and an effective absorptivity is adapted to the proposed model to analyze the melting mode transition. The proposed model can predict the melt pool characteristics including the melt pool dimensions and the melting modes in the selective laser melting (SLM) process. The problem is formulated using the heat transfer equation considering the phase transition and the degree of consolidation based on the phase-field approach. The single-track scans of 316 L stainless steel for both the non-powder case and the powder case are simulated to validate the model and the obtained results are in good agreement with the experimentally measured melt pool dimensions (mean error within 6%). Furthermore, the melting modes (conduction and keyhole) can be distinguished based on the predicted melt pool morphology and the degree of vaporization with the proposed model, which provides insight to define the optimized process boundary. It is also found that the keyhole mode melting is more sensitive to the change of the process parameter than the conduction mode melting.

在本文中，考虑了多孔和致密状态材料的不同吸收机理，开发了一种新型的混合热源模型，并将有效吸收率与所提出的模型相适应，以分析熔融模式的转变。所提出的模型可以预测熔池特征，包括选择性激光熔化（SLM）过程中的熔池尺寸和熔化模式。该问题是根据相场方法，使用考虑了相变和固结度的传热方程来提出的。模拟了非粉末和粉末情况下316 L不锈钢的单道扫描，以验证模型，并且所得结果与实验测量的熔池尺寸非常吻合（平均误差在6％以内）。此外，可以根据预测的熔池形态和汽化程度来区分熔融模式（传导和锁孔），从而为定义最佳工艺边界提供见识。还发现，钥匙孔模式熔化比传导模式熔化对工艺参数的变化更敏感。