STEEL EXCELLENT IN ROLLING FATIGUE LIFE

摘要

PROBLEM TO BE SOLVED: To provide steel excellent in a rolling fatigue life used in machine components and devices by restricting an oxygen content and a sulfur content in the steel, and by detecting nonmetallic inclusions in the steel at a large volume by the ultrasonic flaw detection method to limit the number thereof.SOLUTION: The steel excellent in a rolling fatigue life is steel having surface hardness of 58 HRC or higher and used for machine components and devices, wherein: an oxygen content in the steel is 8 ppm or less by a mass ratio; a sulfur content is 0.008 mass% or less; the number of non-metallic inclusions having a diameter of 20 μm or larger and less than 100 μm detected per a volume of 1,000 mmof the steel by the ultrasonic flaw detection method is 3.5 pieces or less; and the number of non-metallic inclusions having a diameter of 100 μm or larger detected per a weight of 2.5 kg of the steel by the ultrasonic flaw detection method is 1.5 pieces or less.