Steel material for carburized bearing part

1. A steel material for a carburized bearing part, having a chemical composition consisting of, by mass %,

C: 0.25 to 0.45%,

Si: 0.15 to 0.45%,

Mn: 0.40 to 1.50%,

P: 0.015% or less,

S: 0.005% or less,

Cr: 0.60 to 2.00%,

Mo: 0.10 to 0.35%,

V: 0.20 to 0.40%,

Al: 0.005 to 0.100%,

Ca: 0.0002 to 0.0010%,

N: 0.0300% or less,

O: 0.0015% or less

Ni: 0 to 1.00%,

B: 0 to 0.0050%,

Nb: 0 to 0.100% and

Ti: 0 to 0.10%,

with the balance being Fe and impurities, and satisfying Formula (1) to Formula (3):

1.20<0.4Cr+0.4Mo+4.5V<2.75  (1)

A1/A2>0.50  (2)

2.7C+0.4Si+Mn+0.45Ni+0.8Cr+Mo+V>2.55  (3)

where, a content (mass %) of a corresponding element is substituted for each symbol of an element in Formula (1) and Formula (3); if a corresponding element is not contained, “0” is substituted for the symbol of the relevant element; in Formula (2), “A1” represents a gross area (μm 2 ) of sulfides containing Ca in an amount of 1 mol % or more and having an equivalent circular diameter of 1 μm or more in an observation region with a gross area of 4 mm 2 or more in a cross section that is parallel to a rolling direction; and “A2” represents a gross area (μm 2 ) of sulfides having an equivalent circular diameter of 1 μm or more in the observation region.

2. The steel material for a carburized bearing part according to claim 1 ,

wherein the chemical composition contains one or more types of element selected from a group consisting of:

Ni: 0.05 to 1.00%, and

B: 0.0003 to 0.0050%.

3. The steel material for a carburized bearing part according to claim 1 ,

wherein the chemical composition contains one or more types of element selected from a group consisting of:

Nb: 0.005 to 0.100%, and

Ti: 0.01 to 0.10%.

4. The steel material for a carburized bearing part according to claim 2 ,

wherein the chemical composition contains one or more types of element selected from a group consisting of:

Nb: 0.005 to 0.100%, and

Ti: 0.01 to 0.10%.