Steel material for steel piston

Abstract

A steel material has a chemical composition which consists of, in mass %, C: 0.15 to 0.30%, Si: 0.02 to 1.00%, Mn: 0.20 to 0.80%, P: 0.020% or less, S: 0.028% or less, Cr: 0.80 to 1.50%, Mo: 0.08 to 0.40%, V: 0.10 to 0.40%, Al: 0.005 to 0.060%, N: 0.0150% or less, O: 0.0030% or less, and the balance: Fe and impurities, and satisfies Formulae (1) and (2), in which, at a cross section parallel to the axial direction of the steel material for a steel piston, the number of Mn sulfides is 100.0 per mmor less, the number of coarse Mn sulfides having an equivalent circular diameter of 3.0 μm or more is in a range of 1.0 to 10.0 per mm, and the number of oxides is 15.0 per mmor less.0.42≤Mo+3V≤1.50  (1)V/Mo≥0.50  (2)