Effect of aging temperature on the microstructure and tribological behavior of an 18Ni maraging steel manufactured by laser powder bed fusion (LPBF)

Vollständiger Abstract

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Abstract This study addresses the critical knowledge gap regarding the influence of kinetically controlled austenite reversion on the tribological stability of Laser Powder Bed Fusion (LPBF) 18Ni-300 maraging steel. While conventional aging focuses on peak hardness (450–550 °C), this research investigates the high-temperature aging regime (610 °C and 650 °C) to elucidate the correlation between phase meta-stability and the evolution of protective tribo-layers. Samples were characterized using LOM, SEM, and XRD, with wear performance evaluated via pin-on-disk testing. A significant novelty of this work is the identification of a trevorite-rich oxide layer (Ni 0.86 Fe 2+ 0.12 Co 0.01 )Fe 3+ 2 O 4 whose formation is directly promoted by the presence of reverted austenite. In contrast, hematite was found to form predominantly on the martensitic substrate. Results show that prolonging aging at 610 °C from 10 to 30 min reduced hardness from 540 HV 0.2 to 511 HV 0.2 due to precipitate coarsening and increased austenite reversion. Although high-temperature aging enhances wear resistance compared to the as-built state, the higher austenite content at 610 °C facilitated oxide layer detachment, increasing the coefficient of friction (CoF) to 0.58, compared to 0.44 observed at 650 °C. These findings provide a technical basis for optimizing 3D-printed components, shifting the focus from maximum hardness to the engineering of phase-stabilized tribological surfaces.