Fracture mechanism of polycrystalline cubic boron nitride abrasive grains during single-grain grinding of Ti-6Al-4V titanium alloy

Abstract

In this article, high-speed grinding experiments were carried out on Ti-6Al-4V titanium alloy material to investigate the fracture mechanism of polycrystalline cubic boron nitride abrasive grains. The experiments were based on single-grain grinding operation to compare the fracture behavior of polycrystalline cubic boron nitride abrasive grains and monocrystalline counterparts. Considering that the fracture behavior of abrasive grains was influenced by load; moreover, the load was related to grinding depth, and more experiments were conducted to study the effects of grinding depth on the fracture behavior of abrasive grains. In order to observe the fracture behavior, photographs were grasped with 3D optical video microscope and the 3D profile of grain topography was reconstructed. The results obtained indicate that polycrystalline cubic boron nitride abrasive grains are generally more suitable to manufacture the brazed grinding wheels. Due to the particular microstructure, polycrystalline cubic boron nitride abrasive grains are more prone to micro fracture and attritious wear instead of large fracture. Furthermore, the polycrystalline cubic boron nitride abrasive grains usually get worn more seriously with a larger grinding depth.