Study on surface morphology and roughness variation of NiCr alloy curved surface manufactured by selective laser melting

Abstract

In order to directly fabricate customized metallic parts with complicated surface, the surface quality of curved surface feature manufactured by selective laser melting (SLM) technology should be ensured. The parameters of NiCr alloy are optimized by orthogonal experiment and two kinds of cylinders are fabricated with X-Y inter-layer staggered scan strategy. The surface morphologies of curved surfaces of the parts are studied using three dimensional super depth digital microscope and scanning electron microscope, and the corresponding surface roughness is measured. The results show that when fabricating the parts with curved surface placed in different spatial positions, contour error in layer and stair effect among layers stacked lead to the staircase-shaped profile and anastomosing morphology on curved surfaces, and even the worm-like or granular morphology on overhanging curved surfaces when the tilt angle is larger than 60°. Variation of the value of Ra is consistent with surface morphology. The results provide important guidance to improve surface quality of the parts with curved surface fabricated by SLM.