Steel Material

Abstract: The present invention provides a steel material which has excellent fusion cracking resistance, excellent resistance to cracking during hot working and excellent machinability, and which enables a component for machine structures to achieve a high fatigue strength in cases where the component is formed of this steel material. A steel material according to the present disclosure has a chemical composition that is set forth in the description, while having an Fn of 0.45-1.05, the Fn being defined by formula (1). With respect to this steel material, the number density of fine Bi particles that have a circle-equivalent diameter of 0.1-1.0 µm is 15.00 per mm2 or more and the number density of coarse Bi particles that have a circle-equivalent diameter of 10.0 µm or more is 0.25 per mm2 or less at a depth of 0.08R (R represents the radius) from the surface of the steel material; and the number density of the fine Bi particles is less than 15.00 per mm2 and the number density of the coarse Bi particles is more than 0.25 per mm2 at a depth of 0.65R from the surface of the steel material.

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