Process parameter interactions and volumetric energy density Non-Uniqueness in LPBF-Processed CuCrZr alloy: Effects on defect evolution and densification

Purpose This study aims to investigate the densification behavior and defect evolution of CuCrZr alloy fabricated by laser powder bed fusion (LPBF), with emphasis on the effects of laser power (LP), scanning speed (SS), hatch distance (HD) and powder bed layer thickness (PBLT) on density, microstructure, defects and mechanical performance. The suitability of volumetric energy density (VED) for predicting densification and defect formation is also evaluated. Design/methodology/approach A statistically validated experimental framework based on a modified Taguchi method was used to optimize the LPBF process parameters. Eighty-one CuCrZr specimens were fabricated under different processing conditions. Density measurements, optical and scanning electron microscopy, defect characterization and mechanical testing were performed to establish process-structure-property relationships and evaluate the effects of post-heat treatment. Findings The optimized parameters of LP = 370 W, SS = 610 mm/s, HD = 0.10 mm and PBLT = 30 µm produced relative density above 99.6% with minimal defects. Lack-of-fusion defects, gas porosity and interlayer cracking were strongly influenced by melting pool behavior and process parameter interactions. Microstructural analysis revealed a transition from fine equiaxed grains to elongated columnar grains along the build direction. Direct aging produced the highest strength, with a yield strength of 435 MPa and ultimate tensile strength of 437 MPa, while solution treatment followed by aging increased elongation up to 13%. Originality/value The results demonstrate that VED alone is insufficient for predicting densification because different parameter combinations with similar VED values produced distinct density levels and defect morphologies. The modified Taguchi framework provides a systematic approach for optimizing LPBF parameters and establishing relationships between processing conditions, defects, microstructure and mechanical performance of CuCrZr alloy.