Experimental study on surface quality in micro-grinding FeCoNiCr high-entropy alloy prepared by selective laser melting

Selective laser melting (SLM) high-entropy alloy (HEA)-formed parts have certain gaps in dimensional accuracy and surface finish compared with traditional subtractive molding parts, which is the main problem of selective laser melting high-entropy alloy (SLM-HEA) at present. Three different HEAs were prepared using SLM technology, and micro-grinding experiments were carried out to explore the effects of different grinding parameters, processing methods, powder types, and elemental types on the surface roughness, surface morphology, and sub-surface microstructure of SLM-HEAs. The experimental results show that with the increase of grinding speed, the decrease of grinding depth and feed rate, the surface roughness Ra and Rz decrease, and the surface quality improves; under the same processing parameters, the Ra of up-grinding is 37.04% lower than that of down-grinding, the Ra of prealloyed powder HEA is 10.11% lower than that of the mixed powder HEA, and the degree of surface tearing is light. The Ra of FeCoNiCrTi0.5 is 12.52% lower than that of FeCoNiCrAl0.5, and the micro-crushing caused by surface tearing is reduced. The thickness of the grinding metamorphic layer increases with the increase of grinding speed and grinding depth, under the same grinding parameters, the thickness of the grinding metamorphic layer of FeCoNiCrTi0.5 is smaller than that of FeCoNiCrAl0.5. This work provides theoretical guidance and data support for the efficient machining of HEA, which is helpful to the design and manufacture of SLM-HEA parts.