This work reports on soft part turning of carburizing steels using cemented carbide (CC) cutting tools. The emphasis is on the influence of the cleanliness and micro hardness on the machinability of carburizing steel grades. A reference steel grade is included in this study together with a clean steel and an ultra-clean steel. Machining tests are conducted to examine the cutting tool life, the balance between the excessive flank or crater wear and the chip formation. The wear mechanisms are examined by using a scanning electron microscope (SEM) equipped with a back-scatter (BS) detector. It is possible to differentiate between the machinability of the clean steel grades, having only a minor difference in the sulfur and oxygen contents. Furthermore, the longest tool life is obtained when machining the reference steel. The superior machinability of the reference steel R is linked to its high content of sulfur. It is believed that MnS inclusions act as stress raisers in the primary shear zone. Hence, this will improve the chip formation process. The focus of this paper is on the effect of steels cleanliness and micro hardness on the cutting tool life, chip breakability, and resistance to abrasive wear of similar carburizing steel grades in soft part turning.