IMPROVING MACHINABILITY OF HIGH CHROMIUM WEAR-RESISTANT MATERIALS VIA LASERASSISTED MACHINING

The machinability of high chromium wear resistant materials is poor due to their high hardness with a large amount of hard chromium carbides. This study is focused on improving the machinability of high chromium wear resistant materials with different microstructures and hardness levels via laser-assisted machining (LAM). A laser pre-scan process is designed to preheat the workpiece before LAM to overcome the laser power constraint. A transient, three-dimensional LAM thermal model is expanded to include the laser pre-scan process, and is validated through experiments using an infrared camera. The machinability of highly alloyed wear resistant materials of 27% and 35% chromium content is evaluated in terms of tool wear, cutting forces, and surface integrity through LAM experiments using cubic boron nitride (CBN) tools. With increasing material removal temperature from room temperature to 400 degrees C, the benefit of LAM is demonstrated by 28% decrease in specific cutting energy, 50% improvement in surface roughness and a 100% increase in CBN tool life over conventional machining.