| 摘要 |
<p>PROBLEM TO BE SOLVED: To provide manufacturing methods for parts excellent in delayed fracture resistance and screw parts by easy treatment without using expensive alloy elements or shot peening. SOLUTION: After a thread is preformed by applying pre-form rolling 14 to a stem part of a blank material 13 of the screw, quenching treatment 15 is applied thereto, and vanishing 16 is applied thereto by using a finish form rolling die and the thread is finished in a final shape, or after the quenching treatment 15 is applied, screw form rolling is applied to the stem part combining the vanishing 16. When the parts are a pin or a plate, slight pulling-out as the vanishing and light draft by roller are applied. Tensile stress is reduced by imparting compressive residual stress by vanishing, and the delayed fracture resistance is improved, because hydrogen introduced by high-density dislocation is captured and turned into inoxious non-diffensible hydrogen.</p> |
