Patent ID: 6660105
Filing Date: 2003-12-09
Classification: C21D,C22C

Abstract:
A hot rolled case hardening steel in its final hot rolled condition, having good grain coarsening prevention properties during carburization, characterized in that said steel comprises, by mass,0.1 to 0.4% C, 0.02 to 1.3% Si, 0.3 to 1.8% Mn, 0.001 to 0.15% S, 0.030 to 0.04% Al, 0.022 to 0.04% Nb, 0.006 to 0.0186% N, one, two or more selected from0.4 to 1.8% Cr, 0.02 to 1.0% Mo, 0.1 to 3.5% Ni, 0.03 to 0.5% V, and in whichP is limited to not more than 0.025%, Ti is limited to not more than 0.010%, and O is limited to not more than 0.0025%, with the balance being iron and unavoidable impurities, the steel having a Nb(CN) precipitation amount of not less than 0.005% and an AlN precipitation amount that is limited to not more than 0.005%.