STEEL FOR MACHINE STRUCTURE EXCELLENT IN ROLLING FATIGUE LIFE AND ITS PRODUCTION

摘要

PROBLEM TO BE SOLVED: To produce steel for machine structure which can exhibit excellent rolling fatigue life of >=108 repeating number without necessitating a large facility investment and by an actual production scale and a realizable method, and to provide a useful method for manufacturing the steel for machine struc ture. SOLUTION: The steel for machine structure which contains >=10 wt.% CaO and <=5 of number of inclusion of >=5μm major axis within 320 mm2 area to be inspected, is obtained by stirring molten steel after refining for >=40 minutes at 5.0 to 20.0 l/minute gas flow rate per 1 ton of molten steel by using a circulating degassing system vacuum refining processing device.