Steel for machine and structural use having excellent machinability

Abstract

The present invention provides a steel for machine and structural use which sustains mechanical properties such as strength by reducing S content, and exerts excellent machinability (in particular, tool life) in both of intermittent cutting with HSS tools and continuous cutting with carbide tools. The invention relates to a steel for machine and structural use which contains an oxide inclusion containing, wherein a total mass of an average composition of the oxide inclusions is 100%: CaO: 10 to 55 mass %; SiO2: 20 to 70 mass %; Al2O3: more than 0 and 35 mass % or less; MgO: more than 0 and 20 mass % or less; MnO: more than 0 and 5 mass % or less; and one or more members selected from the group consisting of Li2O, Na2O, K2O, BaO, SrO and TiO2: 0.5 to 20 mass % in total.

Dependencies are inferred from the claim text.