Flat plate member with a gear portion and a process for making the same

摘要

A flat plate member with gear portion is formed to a predetermined shape by pressing a flat steel raw material having a composition comprising, by weight, 0.10-0.18% C, less than 0.03% Si, 0.60-1.50% Mn, less than 0.020% P, less than 0.013% S, 0.001-0.004% B and the balance Fe with inevitable impurities, wherein quenching is performed on only the gear portion.