Machining of high chromium hardfacing materials

Hardfacing materials with large chromium carbide are widely used in industry to increase the wear resistance of the component. Its manufacturing process is an important aspect of the overall economy of this technology. Inclusion of large chromium carbides in its microstructure makes these materials very difficult to machine. Development of PCBN tools has opened up the possibility to machine this type of engineering material by conventional turning process to increase the productivity. In this work, the deformation behaviour of the hardfacing material and the wear of PCBN tools are reported. The chip formation was studied by a quick-stop device, and the chip root and the chip were examined to investigate the deformation of the large chromium carbide in the cutting process. It was found that the machining process has involved fracture of large carbides ahead of the cutting edge and bending and cracking of the carbide underneath the transient surface. The main modes of tool wear were identified as edge chipping and flank wear, and mechanical loading and the abrasiveness of the carbide particle were the main cause.