Chip morphology of normalized steel when machining in different atmospheres with ceramic composite tool

Dry cutting tests in air and nitrogen atmospheres with a ceramic cutting tool were carried out on normalized AISI 1045 steel. SEM and EDX techniques are employed to observe the chip morphology and tribological mechanisms are simultaneously discussed. The finite element model of chip formation was created to determine the effective stress and strain distributions in the chip and workpiece. Compared in nitrogen, the friction coefficient in air was reduced when the cutting speed is at 160 m/min and the feed rate is 0.1 mm/r. Experimental data and observation revealed the formation of a lubricating film at the tool-chip interface, which related to the difference chip morphology in air and nitrogen.