Selective laser melting

Inconel 625

Metallurgy

Materials science

Surface finish

Equiaxed crystals

Inconel

Surface roughness

Physics

Alloy

Optics

Lattice constant

Microstructure

Optical microscope

Composite material

Tribology

Scanning electron microscope

Diffraction

Journal of Materials Processing Technology

To study the effect of the building directions on surface macro- / micro- structure and tribological properties of Inconel 625 samples manufactured by selective laser melting (SLM) technology, parts were fabricated in three different building directions (0°, 45°, 90°). The microstructure of SLM samples was characterized using optical microscope (OM) and scanning electron microscopy (SEM). Only the γ-Ni phase was detected in the X-ray diffraction (XRD) patterns of the SLM samples. The lattice constant of the γ-Ni phase in the SLM 45°sample was the lowest among these SLM samples. The value of the surface roughness of the SLM 45° specimen was the highest than other parts, while, the value of the surface roughness of the SLM 0° sample was the lowest. The surface microstructure of the SLM samples was primarily composed of columnar dendrites and equiaxed grains. Among these samples, the finest equiaxed grains (about 0.38−0.63 μm) was evenly distributed in the SLM 0° sample, while, the roughest equiaxed grains (approximately 0.73–1.26 μm) was formed in the SLM 45° sample. Furthermore, the SLM 0° specimen showed the highest microhardness value (332 HV0.2) and the best tribological performances, such as the lowest average coefficient of friction (COF = 0.31) and the wear rate (57.2 × 10−6 mm3 / (Nm)).

Effect of building directions on the surface roughness, microstructure, and tribological properties of selective laser melted Inconel 625