Wear mechanism of aggregated cBN grains during single-grain ultrasonic vibration-assisted grinding of γ-TiAl alloys

Abstract

In this study, the wear mechanism of single aggregated cubic boron nitride (AcBN) grain during ultrasonic vibration-assisted grinding is investigated. The single AcBN grinding experiment are conducted under conventional grinding and ultrasonic vibration-assisted grinding on gamma titanium-aluminum intermetallic compounds, and the grain wear mechanism is comprehensively revealed by observing the radial wear height, normal force, average volume pile-up ratio, and morphology evolution of the grains with different maximum undeformed chip thicknesses, grinding speeds, and ultrasonic amplitudes. The experimental results show that the introduction of ultrasonic vibration produces periodic vibration of the workpiece in the tangential direction, which can produce intermittent dissociative behavior and effectively reduce normal force and average volume pile-up ratio of single AcBN grains when grinding, but also makes the instantaneous maximum undeformed chip thickness increase and introduces the periodic impact force, which accelerates the radial wear height of the AcBN grains. In addition, the ultrasonic vibration can effectively reduce the material adhesion in the AcBN grains surface and cause it to continuously undergo micro-fracture has better self-sharpening ability. In addition, excessive ultrasonic amplitude will lead to AcBN grains to occur macro-fracture and the expansion of bond cracks lead to abrasive grains pulling out, losing partial grinding ability.