The Influence of Microstructure and Non-Metallic Inclusions on the Machinability of Clean Steels

Abstract

This study focuses on the evaluation of the machinability of different carburizing steel grades by using a cemented carbide cutting tool during semi-finishing of steel. The effect of the steel composition, microstructure, and inclusion characteristics on the cutting tool wear in the soft part turning is evaluated for a reference steel R (0.028% S, 0.0009% O), a clean C steel (0.003% S, 0.0005% O), and an UC ultra-clean steel (0.002% S, 0.0004% O). An improved cutting tool life of about 10–25% is obtained when machining the reference steel R. The favorable machining performance of this steel is attributed to its higher content of non-metallic inclusions, larger grain size, and lower micro hardness than that of the clean steels.