| 摘要 |
A steal gear wheel (1) comprises an outer circumferential ring (2) having a tooth profile (10) formed on an outer circumferential surface (20a), and a flange (3) that extends inward from an inner circumferential surface (20b). The outer circumferential ring (2) is provided with a first protruding section (21) that protrudes on one side in the axial direction, and a second protruding section (22) that protrudes on the other side in the axial direction, beyond the part (L) where the outer circumferential ring (2) is linked with the flange (3). The lengths of the first protruding section (21) and the second protruding section (22) in the axial direction are substantially the same. A carburized layer (4) formed on the surface layer of the tooth profile (10), and a thermal history layer (5) are formed on the outer circumferential ring (2). The thermal history layer (5) contains the carburized layer (4), is a deep region having an inward depth from the outer circumferential surface (20a) deeper than that of the carburized layer (4), and has a history of being heated by high-frequency induction heating until becoming austenite. The inward depth (T) of the thermal history layer (5) from the tooth bottom (104) is deeper with regard to the first protruding section (21) and the second protruding section (22) than the part (L) where the outer circumferential ring (2) is linked with the flange (3), and is substantially the same in the first protruding section (21) and the second protruding section (22). |
