| 摘要 |
<P>PROBLEM TO BE SOLVED: To prevent a bolt from loosening up even if vibration is applied in a base material part or a screw part. Ž<P>SOLUTION: A bushing 14 includes the screw part 150 formed as one unit with a metal plate as the base material. An internal screw 15 is provided at the screw part 150. The bushing 14 has metal structure different from that of the screw part 150 at a part between the screw part 150 and the base material part 114 constructing a metal plate, has lower hardness than the screw part 150, and includes a heat-affected zone 112 as a hardness inclination part in which hardness drops from the screw part 150 toward the base material part 114. The screw part 150 is composed of bainite as a major component, the base material part 114 is composed of cementite and ferrite as major components, and the heat-affected part 112 is composed of cementite and ferrite of which structure becomes finer as it gets closer to the base material part as major components. Ž<P>COPYRIGHT: (C)2010,JPO&INPIT Ž
|
