Excellent steel to rolling fatigue life

A content of oxygen in the steel, as well as regulating the sulfur content and Al content, weight% ratio of the average composition of MgO-Al The A surface hardness of steel for use in machine parts to be more 58 HRC, 8 ppm or less oxygen content in the steel at a mass ratio, the sulfur content of 0.008 wt% or less, the Al content 0.011 a 0.030 wt%, the weight% ratio of the average composition of MgO-Al .BACKGROUND