Effect of ultrasonic vibration assisted dry grinding on hysteresis loop characteristics of AISI D2 tool steel

As a cold working tool steel, AISI D2 tool steel is widely adopted in the tooling and automotive industries because of its excellent thermo-mechanical properties. However, the mechanism of chip removal is more intricate by conventional machining owing to its work straining phenomena. Besides, this material can be effectively machined and finished by advanced grinding such as brittle fracturing mechanism. Hence, the present experimental study attempts to compare the surface integrity characterization of AISI D2 tool steel upon conventional dry grinding (CDG), and ultrasonic vibration assisted dry grinding (UVADG) using non-destructive magnetic technique, i.e., hysteresis loop (HL). The surface integrity of ground sample was evaluated in terms of surface roughness, 2-D surface profile, microstructure, and microhardness. These surface integrity outcomes were compared with HL outcomes such as average permeability, remanence, coercivity, and core loss. The experimental results revealed that minimum phase transformation and microhardness variation were observed in the ground surface under UVADG compared to CDG mode due to intermittent shearing action of abrasive grits over work material, which restricts excessive heat penetration. The lower surface roughness was found under UVADG mode, which is Ra: 0.118 µm and Rz: 0.671 µm, respectively. Furthermore, excellent correlation was observed in magnetic response, i.e., significant changes in HL profile and better HL outcomes, and it was associating well with the microstructure and variations in microhardness, resulting from UVADG of ground sample.