Patent ID: 8920582

Claim:
A steel material which has a chemical composition comprising, in mass percent, C: 0.05-0.35%, Si: at most 0.5%, Mn: 0.5-2.5%, P: at most 0.03%, S: at most 0.01%, sol. Al: at most 0.1%, N: at most 0.01%, B: 0-0.005%, Ti: 0-0.1%, Cr: 0-0.5%, Nb: 0-0.1%, Ni: 0-1.0%, and Mo: 0-0.5%, and which has a steel structure containing carbides, with the spheroidization ratio of the carbides being 0.60-0.90, a number density of the carbides being at least 0.50 carbides per μm 2 , and the proportion of the number of coarse carbides having a particle diameter of at least 0.5 μm in the carbides is at most 0.15.