Effect of S addition on mechanical and machinability properties in austenitic Fe-Mn-Al-C lightweight steels

In this study, the machinability of austenitic LWS and the effect of MnS formation on the mechanical and machinability properties were investigated. For this purpose, S was added over a wide range from 0.0048 to 0.0713 wt% to control MnS inclusions. As the S content increased, the number and area fraction of the MnS inclusions increased linearly, whereas the inclusion size first rapidly increased, and then its slope decreased. The tensile properties hardly changed regardless of the S content, whereas the Charpy impact energy deteriorated linearly with increasing S content. Furthermore, the machinability of LWS was considerably improved by the formation of MnS inclusions, which play a role in the site of mechanical stress concentration and thermal cavity and pore generation during machining.

Automated summary

This study investigates the machinability of austenitic LWS and the impact of MnS formation on its mechanical and machinability properties. The research finds that the number and area fraction of MnS inclusions increase linearly with the increase of S content, while the size of inclusions first increases rapidly and then slows down. The tensile properties remain unchanged regardless of the S content, but the impact energy deteriorates linearly with the increase of S content. Additionally, the formation of MnS inclusions significantly improves the machinability of LWS by acting as sites of mechanical stress concentration and generating thermal cavity and pores during machining.