Patent ID: 7387691

Claim:
A hot forged non-heat treated steel for induction hardening, which comprises by mass percent, C: 0.35 to 0.45%, Si: 0.20 to 0.60%, Mn: 0.40 to 0.80%, S: 0.040 to 0.070%, Cr: 0.10 to 0.40%, Ti: 0.030 to 0.100%, Ca: 0.0005 to 0.0050%, B: 0.0005 to 0.0030%, O (oxygen): 0.0015 to 0.0050%, Mo: 0 to 0.05%, P: 0.025% or less, V: 0.03% or less, Al: 0.009% or less and N: 0.0100% or less, with the balance being Fe and impurities, in which the value of Fn1 represented by the following equation (1) is 0.63 or less, the value of Fn2 represented by the following equation (2) is 1.0 or less, and the value of Fn3 represented by the following equation (3) is 5.7 or more: Fn 1=C+(Si/10)+(Mn/5)+(5Cr/22)+1.65V−(5/7S)+1.51×(Ti−3.4N), Equation (1) Fn 2=Ca/O, Equation (2) Fn 3=25.9× Fn 1+27.5×(Ti−3.4N)−7.9. Equation (3).