Experimental study of micromilling selective laser melted Inconel 718 superalloy

Abstract

This study investigated micromilling of Inconel 718 made by selective laser melting (SLM) additive manufacturing. Emphasis was placed on the effects of tool coating, milling parameter, and SLM scanning strategy on the surface roughness and resulting tool wear. Surface and volume defects such as pores and embedded slags between layers reduced the effectiveness of micromilling. Although uncoated WC tools did not performed satisfactorily, coated tools were promising but had to operate at lower cutting speeds compared to those for extruded/rolled materials. The AlTiN/Si3N4 PVD coating out-performed the AlTiN coating, and a surface finish of 1-2 µm Ra was achieved. Empirical models suggested that tool life not only affected by scanning strategy during SLM, but also influenced by cutting speed more than applied chip load. Hot isostatic pressing significantly shorten the tool life and worsened the surface finish.