Grain wear of brazed polycrystalline CBN abrasive tools during constant-force grinding Ti–6Al–4V alloy

摘要

Constant-force grinding experiments of titanium alloy Ti–6Al–4V were carried out with brazed polycrystalline cubic boron nitride (PCBN) abrasive wheel heads. Stock removal and tool wear of PCBN abrasive tools were evaluated by comparison with that of monocrystalline CBN counterparts. Grain wear of the brazed PCBN abrasive tools were examined using optical microscopy and scanning electron microscopy. Fracture mechanism of the PCBN abrasive grains was discussed. The results show that the brazed abrasive tools with PCBN grains give larger stock removal by 25% and the longer service life by 30% than the tools with CBN grains. PCBN abrasive grains have the capability to maintain sharp cutting edges by means of the fracture behavior of microcrystalline CBN particles. In case of strong fixing of the PCBN grains in the Ag–Cu–Ti filler layer, the crack of PCBN abrasive grains are mainly dominated in the intergranular mode dependent upon the joining effects of AlN binder material among the adjacent microcrystalline CBN particles.