Pore evolution and porosity mitigation in laser powder bed fusion of Ni-Cr-Fe based superalloy

作者：Dong Liu, Yue Pan, Hua Hou, Yuhong Zhao · 发表于：International Journal of Heat and Mass Transfer · 年份：2025 · DOI：10.1016/j.ijheatmasstransfer.2025.127781 · 被引用次数：6 · 研究领域：Additive Manufacturing Materials and Processes、High Entropy Alloys Studies、Additive Manufacturing and 3D Printing Technologies

Porosity defects generated during laser powder bed fusion (LPBF) pose critical challenges to the mechanical integrity of fabricated components, potentially limiting the industrial adoption of metal additive manufacturing technologies. While Ni-Cr-Fe-based superalloys are widely employed in high-temperature applications, systematic investigations into pore formation dynamics during LPBF processing remain insufficient. This study establishes a high-fidelity three-dimensional multiphase numerical model incorporating fluid-solid coupling and vaporization effects to elucidate pore evolution mechanisms. Through parametric analysis of laser power, scanning speed, and spot diameter, we quantitatively characterize the interdependent relationships between process parameters, keyhole stability, and porosity formation. The model reveals three processes of pore evolution: 1) gas cavity entrapment through keyhole collapse, 2) bubble coalescence and growth, and 3) vapor-phase escape dynamics. Quantitative analysis revealed that penetration depth ( R 2 = 0.96 ) exhibited high sensitivity to energy density, while penetration depth demonstrated a correlation with porosity ( R 2 = 0.91 ). A novel criterion based on keyhole aspect ratio ( A R k ≤ 1.82 ) is proposed to ensure melt pool stability, supported by an optimized processing window in the P-v space. These findings provide critical insights for defect mitigation strategies in high-performance alloy additive manufacturing.