The Development of Nanocrystalline CBN for Enhanced Superalloy Grinding Performance

Abstract

CBN grinding wheels are increasingly used on a wide range of engineering materials. This paper compares the grinding performance of monocrystalline (M-CBN) and polycrystalline (P-CBN) abrasives with a newly developed nanocrystalline (N-CBN) abrasive, when grinding nickel-based superalloys. The N-CBN grits possess average crystal grain diameters less than 1 μm compared to average primary grain diameters of 2.3 μm for P-CBN. It was found that the nanocrystalline CBN grits possess higher fracture strength which give reduced wear rates and yield an order of magnitude increase in grinding wheel life. Analysis of the cutting edge distribution shows that the reduced wear rate of N-CBN is due to the predominance of a micro-fracturing mode of abrasive wear. The size of this micro-fracturing is considerably smaller in N-CBN than in P-CBN.