STEEL FOR MACHINE STRUCTURES

• Main Authors: IWAHASHI TAKANORI, EGASHIRA MAKOTO, TOUDOU SHOUJI, HASHIMURA MASAYUKI
• Format: Patent
• Language: Chinese; English
• Published: 19.03.2019
• Subjects: ALLOYS; CASTING; CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES; CHEMISTRY; FERROUS OR NON-FERROUS ALLOYS; METALLURGY; METALLURGY OF IRON; PERFORMING OPERATIONS; POWDER METALLURGY; PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OFWROUGHT-IRON OR STEEL; TRANSPORTING; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS

A steel for machine structures is provided which has excellent machinability, rusting characteristics and hot rolling properties and from which carburized components with excellent rolling fatigue characteristics can be obtained. This steel for machine structures has a chemical composition which satisfies expression (1) and contains, in mass%, C: 0.15 to less than 0.30%, Si: 0.01-0.80%, Mn: 0.20-2.00%, P: 0.030 or less, S: 0.010-0.100%, Pb: 0.010-0.100%, Al: 0.010-0.050%, N: 0.015% or less, O: 0.0005-0.0030% and Cr: 0.50%-2.00%, the remainder being Fe and impurities. The total number of specific inclusions included in the steel that are MnS inclusions, Pb inclusions, or composite inclusions containing MnS and Pb and that have a circle equivalent diameter of greater than or equal to 5 mu mis greater than or equal to 40 inclusions/mm2. Mn/S >= 8.0 (1) Here, each element in formula (1) is substituted with the amount contained (mass%) of the corresponding element. 提供能得到切削性、生锈特性和热延性优异、滚动疲劳特性优异的渗碳部件的机械结构用钢。本实施方式的机械