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

• The printing process of NiCrFe-based superalloy powder was systematically investigated through coupled Discrete Element Method and Computational Fluid Dynamics (DEM-CFD). • Parametric studies were conducted to elucidate pore evolution mechanisms during melting-solidification transitions. • Three critical process parameters were statistically analyzed for their impacts on melt pool stability and pore defect formation. • A porosity mitigation criterion was developed based on keyhole aspect ratio characterization through multi-physics modeling. • A practical quality control chart was established with process windows optimized for industrial LPBF applications. 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.