Machinability of bainitic steels

Abstract

The heavy-vehicle industry's drive to reduce manufacturing energy has ignited an interest in bainitic steels. These steels can attain their required properties through controlled cooling and thereby avoid energy intensive heat treatments. However, their machining behaviour remains less understood than their mechanical performance. This work investigates the machinability of a bainitic steel intended for trucks and compares it with a quenched and tempered (Q&T) steel currently in use. Both workpiece materials were characterized in terms of microstructure, non-metallic inclusion population and hardness profiles, after which face turning tests were conducted for both materials under identical cutting conditions. The forces were measured during the cutting process with the use of a dynamometer, while the tool wear response was characterized using scanning electron microscopy and energy-dispersive X-ray spectroscopy. In general, the bainitic steel exhibited worse machinability, exhibiting higher flank wear across all investigated cutting conditions. The difference in machinability was then discussed in light of the microstructural differences between both materials.