| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a pinion which has excellent wear resistance, further has excellent machinability and is easy to be produced, and to provide an inexpensive rack and pinion type steering device having a long service life. <P>SOLUTION: The pinion 22 of the rack and pinion type sheering device is composed of a steel in which the content of carbon is 0.38 to 0.75 mass%, the content of silicon is 0.11 to 0.83 mass%, the content of manganese is 0.5 to 2.03 mass%, the content of chromium is 0.8 to 1.5 mass% and the content of molybdenum is ≤0.5 mass%, and also satisfying an equation value of ≥5.9. Further, it is hardened by induction hardening process, and in which the hardness of a tooth face is ≥600 Hv. Further, the amount of carbides in each depth position from a depth position at the inside by 1.0 mm of the tooth face to the tooth face is 0.51 to 2.97% by area ratio. Further, the structure of an un-hardened part is a tempered structure or a normalized structure. <P>COPYRIGHT: (C)2013,JPO&INPIT |
