Steel material

Abstract

A steel material according to the present disclosure consists of, by mass %, C: 0.30 to 0.50%, Si: 0.01 to 0.30%, Mn: 0.10 to 1.50%, P: 0.030% or less, S: 0.030% or less, Cr: 0.01 to 0.80%, Mo: 0.70 to less than 1.50%, V: 0.01 to 0.50%, Al: 0.005 to 0.100%, and N: 0.0010 to 0.0300%, with the balance being Fe and impurities. The area fraction of hard structure is 90% or more and the Vickers hardness is 220 to 400 HV. The number density of cementite particles in the hard structure is 4.0 pieces/μm 2 or more. The number ratio of cementite particles having an area of 0.0005 to 0.0100 μm 2 among a plurality of the cementite particles in the hard structure is 50.0% or more. The sample standard deviation of the areas of a plurality of the cementite particles in the hard structure is 0.070 μm 2 or less.

1 . A steel material consisting of, by mass %,
 C: 0.30 to 0.50%,   Si: 0.01 to 0.30%,   Mn: 0.10 to 1.50%,   P: 0.030% or less,   S: 0.030% or less,   Cr: 0.01 to 0.80%,   Mo: 0.70 to less than 1.50%,   V: 0.01 to 0.50%,   Al: 0.005 to 0.100%,   N: 0.0010 to 0.0300%,   Cu: 0 to 0.40%,   Ni: 0 to 0.40%,   B: 0 to 0.0100%,   Zr: 0 to 0.300%,   Hf: 0 to 0.100%,   Ta: 0 to 0.100%,   W: 0 to 0.200%,   Ti: 0 to 0.100%,   Nb: 0 to 0.100%,   Ca: 0 to 0.0050%,   Mg: 0 to 0.0050%,   Bi: 0 to 0.020%, and,   Te: 0 to 0.010%,   with the balance being Fe and impurities,   wherein:   an area fraction of hard structure is 90% or more and a Vickers hardness is 220 to 400 HV; and   a number density of cementite particles having an area of 0.0005 μm 2  or more in the hard structure is 4.0 pieces/μm 2  or more, a number ratio of the cementite particles having an area of 0.0005 to 0.0100 μm 2  among a plurality of the cementite particles in the hard structure is 50.0% or more, and a sample standard deviation of areas of a plurality of the cementite particles in the hard structure is 0.070 μm 2  or less.   
     
     
         2 . The steel material according to  claim 1 , comprising one or more elements selected from a group consisting of:
 Cu: 0.01 to 0.40%,   Ni: 0.01 to 0.40%,   B: 0.0001 to 0.0100%,   Zr: 0.001 to 0.300%,   Hf: 0.001 to 0.100%,   Ta: 0.001 to 0.100%,   W: 0.001 to 0.200%,   Ti: 0.001 to 0.100%,   Nb: 0.001 to 0.100%,   Ca: 0.0001 to 0.0050%,   Mg: 0.0001 to 0.0050%,   Bi: 0.001 to 0.020%, and   Te: 0.001 to 0.010%.