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Abstract

A steel material contains, in mass %, C: 0.30 to 0.50%, Si: 0.40% or less, Mn: 0.10 to 0.60%, P: 0.030% or less, S: 0.030% or less, Cr: 0.90 to 1.80%, Mo: 0.30 to 1.00%, Al: 0.005 to 0.100%, and N: 0.003 to 0.030%, with the balance comprising Fe and impurities. When a Cr concentration in an extraction residue obtained by electrolyzing and removing a region from a surface of the steel material to a depth position of 100±20 μm by performing a preliminary constant current electrolysis and thereafter further electrolyzing a region from a surface of the steel material to a depth position of 100±20 μm by performing a main constant current electrolysis is defined as “[Cr]” (mass %), and a Mo concentration in the extraction residue is defined as “[Mo]” (mass %), the steel material satisfies Formula (1).

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