Patent ID: 9115415
Filing Date: 2015-08-25
Classification: B22D,C21D,C22C

Abstract:
1. A case hardened steel comprising, in mass %: C: 0.05 to 0.3%, Si: 0.01 to 0.6%, Mn: 0.20 to 1.0%, S: 0.001 to 0.025%, Cr: 1 to 2.5%, Al: 0.01 to 0.10%, Ti: 0.01 to 0.10%, Nb: 0.01 to 0.10%, B: 0.0005 to 0.005%, N: 0.002 to 0.02%, and iron, wherein: a number density of precipitates that comprise Ti, Nb, or both and have a size of not less than 20 μm a number density of precipitates that comprise Mn, S, and at least one of Ti and Nb and have a size of more than 5 μm a ferrite fraction is more than 77% by area.