Non-heat treated steel bar

A non-heat treated steel bar comprising a chemical composition consisting of, in mass percent:

• C:
• 0.39 to 0.55%;
• Si:
• 0.10 to 1.00%;
• Mn:
• 0.50 to 1.50%;
• P:
• 0.010 to 0.100%;
• S:
• 0.040 to 0.130%;
• Cr:
• 0.05 to 0.50%;
• V:
• 0.05 to 0.40%;
• Ti:
• 0.10% to 0.25%;
• Al:
• 0.003 to 0.100%;
• N:
• 0.020% or less;
• Cu:
• 0 to 0.40%;
• Ni:
• 0 to less than 0.20%;
• Mo:
• 0 to 0.10%;
• Pb:
• 0 to 0.30%;
• Te:
• 0 to 0.3000%;
• Ca:
• 0 to 0.0100%;
• and
• Bi:
• 0 to 0.3000%, with the balance being Fe and impurities including oxygen, the chemical composition satisfying Formula (1), wherein
• in the steel bar, a number density of Al2O3-based inclusions in each of which Al2O3is contained at 70.0% or more in mass percent and √AREA is not less than 3 μm is 0.05 to 1.00/mm2:
• 0.60≤C+0.2Mn+0.25Cr+0.75V+0.81Mo≤1.00 (1)
• where symbols of elements in Formula (1) are to be substituted by contents of corresponding elements (in mass percent).