| 摘要 |
PROBLEM TO BE SOLVED: To provide a quenched and tempered steel strip provided with wear resistance and fatigue properties equal to those of parts obtainable by the conventional general process. SOLUTION: The quenched and tempered steel strip has a chemical composition comprising≥0.3 mass% C, and in which C equivalent is≥0.3% expressed by formula (1): C equivalent (%)=C+Si/24+Mn/6+Cr/5+B×5+V/14+Mo/4+Ni/40, and in which average hardness of the surface layer part 50μm is regulated to≥450 HV, by quenching and tempering treatment accompanied by rapid cooling from an austenite temperature region after a carburizing treatment and also, a difference between the carbon concentration C<SB>s</SB>(mass%) in the surface and the average carbon concentration C<SB>M</SB>(mass%) in the steel:ΔC=C<SB>S</SB>-C<SB>M</SB>is≥0.03 mass%. COPYRIGHT: (C)2011,JPO&INPIT |
