Rapid process mapping via single-track defectology: A roadmap to a defect-free window for Hastelloy X additive manufacturing

This study introduces a systematic defectology framework for process optimization in selective laser melting of Hastelloy X through single-track evaluation. A four-tier defect classification system was developed, linking observable melt-pool morphologies to quantitative criteria including a depth-to-width ratio threshold of 1.5. Sixty single-track experiments spanning 120–360 W laser power and 500–3000 mm/s scan speed were evaluated using integrated top-view and cross-sectional analysis. The methodology identified a defect-free processing window at 210–360 W and 700–1300 mm/s with 40 μm layer thickness, simultaneously suppressing balling, keyholing, and lack-of-fusion defects. Cross-sectional metallography validated that surface indicators reliably predict subsurface melt-pool instabilities, thereby mitigating the primary sources of keyhole-induced porosity, and enabling real-time assessment without extensive post-processing. Framework transferability was demonstrated across different SLM platforms and powder batches through energy-input recalibration. A consolidated defect summary table provides guidance on defect types, detection methods, thresholds, and mitigation strategies. Future validation will extend to multilayer builds targeting >99.5 % densification and >230 HV hardness, with planned X-ray computed tomography integration. This defectology approach represents a significant advancement toward in-situ quality control and accelerated parameter optimization in additive manufacturing of high-performance superalloys.