STEEL MATERIAL

摘要

This steel material comprises, in mass%, C: greater than 0.05% to 0.18%, Mn:1-3%, Si: greater than 0.5% to 1.8%, Al: 0.01%-0.5%, N: 0.001%-0.015%, V and/or Ti: total 0.01%-0.3%, Cr:0%-0.25%, Mo:0%-0.35%, and the remainder: Fe and impurities. In area%, this steel material comprises 80% or more of bainite, and a total of 5% or more of one or more of ferrite, martensite and austenite. The average block size of the bainite is less than 2.0mum, the average particle diameter of the aforementioned ferrite, martensite and austenite together is less than 1.0mum, the average nanohardness of the bainite is 4.0-5.0GPa, and the average spacing between MX-type carbides having a circle equivalent diameter of 10nm or greater is 300nm or less.