M300-C18150 bimetal 3D printing by laser powder bed fusion: effect of process parameters on single track and layer development

Powder Bed Fusion of metals using laser beam (PBF-LB/M) relies on stable single-track and single-layer deposition to produce dense, and defect-free components, a requirement that is particularly challenging in bimetallic systems with dissimilar thermophysical properties. This study investigated the effects of PBF-LB/M process parameters on single-track and single-layer deposition in a bimetallic system comprising M300 maraging steel and C18150 copper alloy. An SLM 280 2.0 2MA PBF-LB/M machine equipped with twin 700 W IPG Ytterbium fiber lasers was used to print the bimetal samples. Laser scan velocities (500–1100 mm/s), laser powers (300–550 W), and hatch spacings (0.08–0.14 mm) were systematically varied for deposition of M300 on C18150 substrates and vice versa. Surface integrity was quantified using surface roughness parameters (Ra and Sa), while melt pool geometry and interfacial characteristics were analysed using optical and scanning electron microscopy. For single tracks of M300 deposited on C18150, increasing scan velocity led to higher surface roughness and reduced melt pool width and depth, whereas higher laser power increased melt pool dimensions. In contrast, single tracks of C18150 deposited on M300 exhibited discontinuous tracks, high variability in melt pool geometry, and unstable deposition behaviour. Single-layer results revealed smoother surfaces for M300 on C18150 under low scan velocity, 500–700 mm/s, small hatch spacing, 0.08–0.1 mm and high laser power, 400–450 W. The reverse configuration, C18150 on M300, however, rendered better surface quality at the same velocity and hatch space ranges but at higher power, 500–550 W. The lowest surface roughness (Ra = 15.7 ± 1.9 μm; Sa = 19.9 ± 0.4 μm ) was for M300 on C18150 configuration and for C18150 on M300 (Ra = 14.9 ± 7.1 μm; Sa = 48 ± 16 μm). Interfacial analysis showed material intermixing in both configurations, with more pronounced defect formation when depositing C18150 on M300. Overall, the results of this study provide critical insights into the process–structure relationships governing bimetallic PBF-LB/M fabrication and contribute to the advancement of parameter optimisation strategies for the production of structurally sound bimetallic components.