| 摘要 |
PROBLEM TO BE SOLVED: To provide a method for greatly improving relaxation resistance in a steel bolt by adopting a relatively simple means. SOLUTION: The steel bolt 1 having a bolt head 4 is prepared at one end of a screw shaft 3 having an external thread section 2 that is screwed into an internal thread hole 12 in a member 13. The external thread section 3 is screwed into a retention hole 10 having an internal thread in a bolt retaining tool 7 at least by a screwing length L<SB>2</SB>or more in clamping while being screwed into the internal thread hole 12 in the member 13 in use. Then, a tensile stress in the direction of an axis exceeding the elastic limitation of a part 11 is applied to the axial section 11 between a screwing end terminal (a) in the external thread section 2 and the bolt head 4 in the screw shaft 3, and the axial section 11 is set to be a region A<SB>1</SB>where stress is applied. After that, heat treatment is made to a region A<SB>1</SB>where stress is applied, where a heating temperature T is 200°C≤T≤300°C, and the region A1 is set to be a region A<SB>2</SB>that is loaded with stress and is heated. COPYRIGHT: (C)2004,JPO
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