Machining behavior of additively manufactured and cast-wrought nickel-based superalloy (IN 625)

Abstract

Additively manufactured (AM) and cast-wrought (CW) nickel-based superalloy (IN 625) with known processing history and quasi-static properties have been investigated for their relative machinability, in terms of tool temperature and wear, as well as machining force and chip morphology. Transparent cutting tools were used to cut tubular specimens of both materials. Visible and near infrared radiation emitted by the chip-tool interface was measured through the transparent tool using an image intensified CCD camera. A calibration procedure was used to convert this into apparent blackbody temperature from which the true temperature was inferred using literature values of emissivity of polished IN 625. Machining forces along the cutting and thrust force directions were measured using a dynamometer. Tool wear and chip morphology were characterized by measurement of tool volume loss and by scanning the chip upper side, using a 3D profilometer. It was found that during machining, AM IN 625 behaves differently from CW IN 625 of similar chemical composition. Significant differences in tool temperature, tool wear, and chip formation mechanisms were observed.