Akademik Veri Yönetim Sistemi
Journal of Materials Research and Technology, cilt.42, ss.3702-3723, 2026 (SCI-Expanded, Scopus)
Reliable process window selection in laser powder bed fusion (LPBF) requires a metric that captures the complex interplay between laser parameters and material response without machine- or material-specific empirical recalibration. This work introduces and validates an absorptivity-calibrated normalized enthalpy NEη as a dimensionless framework for LPBF of IN625, enabling direct prediction of track geometry and defect formation across a wide parameter space. Absorptivity η∈[0.33,0.88] is determined in situ from the dimensionless penetration depth δ∗=D/(2ω), yielding consistent NEη assignments across 23 power–speed (P–v) pairs (150 W to 350 W; 288 mm s-1 to 4356 mm s-1). Single tracks are printed on top of a bulk specimen after deposition of 75 layers; their geometry is then comprehensively characterized and mapped against NEη: surface profilometry quantifies arithmetic mean roughness Ra; X-ray computed tomography (XCT) resolves pore size, morphology, and spatial distribution; and electron backscatter diffraction (EBSD) maps microstructural evolution. Four distinct processing regimes are identified with clear NEη thresholds: balling (NEη<5), conduction (5≤NEη<10), stable keyhole (10≤NEη≤13), and unstable keyhole (NEη≳13). Within the conduction-to-stable-keyhole range, Ra decreases monotonically with increasing NEη. Beyond the instability threshold, XCT reveals a transition from sparse, near-circular pores to larger, irregular defects (projected areas up to 1860 µm2) concentrated near the keyhole root, consistent with capillary-driven keyhole collapse. Kendall rank correlations confirm statistically significant trends with NEη: melt pool depth (τb=1.00, by construction of the calibration), width (τb=0.77), and surface roughness Ra (τb=−0.45). Crucially, the iso-NEη principle is experimentally validated: distinct P–v combinations sharing the same NEη reproduce equivalent track cross-sections and Ra values, confirming the framework’s predictive power. The calibrated thresholds, surface profilometry, and XCT metrics reported here provide immediately actionable guidance for process mapping and qualification of IN625, and the absorptivity-calibration methodology is transferable to other LPBF alloys.