Formation characteristics of nickel-based diamond abrasive segment by selective laser melting

Abstract

Selective Laser Melting (SLM) technique provides an alternative to fabricating a metal bond grinding wheel with a high porosity ratio and controllably complex geometries. In this paper, SLM is applied to making nickel-based diamond abrasive segments based on single-tracks SLM tests. The characteristics of the SLMed wheel segments are investigated through analyses on morphology, porosity, cracks, and diamond grains. Balling phenomenon of the Ni-Cr alloys, which leads to the rough surface and porosities, is observed through the surface and cross-sectional observations. The porosity ratio of the as-built abrasive segment ranges from 22.6% to 27.3%. Two types of diamond spatters, entrainment-driven and vapor-driven diamond spatters, are formed in the SLM process based on the observation by a high-speed video camera. Diamond spatters are considered the main cause of the balling phenomenon. Based on microstructure and hardness measurements, the eutectic structure and granular crystallites result in high hardness and increase the cracking susceptibility of the Ni-Cr alloys. This paper reveals the formation characteristics of the SLMed nickel-based wheel segments and the mechanism of porosity formation in the SLM process.