Shot peening
From Wikipedia, the free encyclopedia
Shot peening is a process used to produce a compressive residual stress layer and modify mechanical properties of metals. It entails impacting a surface with shot (round metallic or ceramic particles) with force sufficient to create plastic deformation. It is similar to sandblasting, except that it operates by the mechanism of plasticity (physics) rather than abrasion: each particle functions as a ball-peen hammer. In practice, this means that less material is removed by the process, and less dust created.
Peening a surface spreads it plastically in the manner of a rivet, causing changes in the mechanical properties of the surface. Shot peening is often called for in aircraft repairs to relieve tensile stresses built up in the grinding process and replace them with beneficial compressive stresses. See the article on peening for more on this effect.
Shot peening may be used for cosmetic effect. The surface roughness resulting from the overlapping dimples causes light to scatter upon reflection. Because peening typically produces larger surface features than sand-blasting, the resulting effect is more pronounced. Shot-peened aluminium sheet, for example, resembles white stone, and was used in the expansion of the Hearst Memorial Mining Building at the University of California, Berkeley.
[edit] See also
- Almen strip
- Autofrettage, which produces compressive residual stresses in pressure vessels.
- Case hardening
- Differential hardening
- Peening
[edit] External links
- www.rosler.com Shot peening-process and equipment
- Surface Treatment — Mechanical
- Metal Improvement Company homepage — information on shot peening and how it strengthens metal
- Shot Peening Universe FAQ
