| 摘要 |
A process of cold working followed by rapid recrystallization imparts a localized fine grain morphology in and around surfaces of fastener holes and edges in aluminum materials. A peening tool that may be employed for surface cold working includes a hollow housing with openings for retaining a plurality of ball peens that may be driven by rotating cams or an oscillating tapered piston operating within the housing to force the ball peens to impact the surfaces of an edge, cavity, or fastener hole to which the tool is applied. The tool may be shaped to accommodate straight bored, counter bored, countersunk, and/or edge surfaces and may be applied manually or automatically for cold working over substantially the entire surface area of the edge or cavity. The peening tool effects localized cold working to a predetermined and controlled depth to break up the existing large pancake-shaped grain structure in the surface of the aluminum alloy. After the surfaces have been cold worked, rapid heating recrystallizes the cold worked surfaces to attain a localized fine grain corrosion and fatigue resistant microstructure. The process provides the benefits of exfoliation corrosion resistance and improved fatigue life by using microstructural control rather than chemical coatings that may be harmful to the environment. The process produces a stable microstructure that allows subsequent use of other treatments to act in parallel as multiple barriers to corrosion.
|
