Production manner null of the superficial charring boron steel which prevents the abnormal grain growth of the crystal grain

摘要

PROBLEM TO BE SOLVED: To provide a method for manufacturing a case-hardened boron steel superior in cold workability, impact resistance, carburization properties, and preventing properties for abnormal grain growth during carburization. ;SOLUTION: The method for manufacturing the case-hardened boron steel while preventing the abnormal growth of the crystal grains, comprises heating the case-hardened boron steel containing 0.0010 to (0.042(N-0.29Ti)+0.0029) wt.% B in the case of ((N-0.0012)/0.29 wt.% or less Ti and (N-0.29Ti)≥0.0042, and 0.0010 to (0.69(N-0.29Ti)+0.0002) wt.% B in the case of (N-0.29Ti)0.0042, to 1,150°C or higher; hot working it; and then heat-treating it at 600-1,000°C for 30 minutes to 10 hours at least one time.;COPYRIGHT: (C)2004,JPO