Hearst Mining building (stone, left) with expansion (shot peened aluminum alloy, right).

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, glass or ceramic particles) with force sufficient to create plastic deformation. It is similar to sandblasting, except that it operates by the mechanism of plasticity 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. Image File history File links Download high resolution version (1600x1200, 599 KB)A shot the Hearst Memorial Mining Building that includes one of its expansions. ... Image File history File links Download high resolution version (1600x1200, 599 KB)A shot the Hearst Memorial Mining Building that includes one of its expansions. ... Illustration of a physical process: a geyser in action. Process (lat. ... This article is about metallic materials. ... Man sandblasting a stone wall Device used for adding sand to the compressed air (top of which is a sieve for adding the sand) Diesel powered compressor used as an air supply for sandbasting Sandblasting or bead blasting[1] is a generic term for the process of smoothing, shaping and... For other uses, see Plasticity. ... In materials science, wear is the erosion of material from a solid surface by the action of another solid. ... A 380 mm (15 in) ball-peen hammer. ...

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. Usually, peening can increase life-time of parts up to 15%. A 380 mm (15 in) ball-peen hammer. ... A rivetted buffer beam on a steam locomotive A rivet is a mechanical fastener consisting of a smooth cylindrical shaft with heads on either end, the second one formed in position. ...

Plastic deformation induces a residual compressive stress in a peened surface, along with tensile stress in the interior. Surface compressive stresses confer resistance to metal fatigue and to some forms of corrosion. The tensile stresses deep in the part are not as problematic as tensile stresses on the surface because cracks are less likely to start in the interior. In physics and materials science, plasticity is a property of a material to undergo a non-reversible change of shape in response to an applied force. ... Fatigue may refer to: Fatigue (physical) - tiredness in humans Fatigue (material) - failure by repeated stress in materials Fatigues (uniform) - military uniform (BDU or ACU) Chronic Fatigue Syndrome - a medical condition Battle fatigue - also known as Post-traumatic stress disorder Readers fatigue - a side-effect of parsing poorly formatted textual... For the hazard, see corrosive. ...

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. The reflection of a bridge in Indianapolis, Indianas Central Canal. ...

See also

• Almen strip
• Autofrettage, which produces compressive residual stresses in pressure vessels.
• Case hardening
• Differential hardening
• Peening

An Almen strip is a thin stip of steel used in the control of a shot peening process. ... Autofrettage is a metal fabrication technique in which the stock is momentarily subjected to enormous pressure. ... A replica Colt 1873 revolver, showing case hardening colors on the frame Case hardening or surface hardening is the process of hardening the surface of a metal, often a low carbon steel, by infusing elements into the materials surface, forming a thin layer of a harder alloy. ... A differential hardening is a method used in forging swords and knives to increase the hardness of the edge. ... A 380 mm (15 in) ball-peen hammer. ...

External links

• Cut Wire Shot - Shot Blasting Media/Abrasive
• Surface Treatment — Mechanical
• Metal Improvement Company Explanation and video on shot peening process and how it increases resistance of metal to fatigue.
• Shot Peening Universe FAQ
• Wheelabrator Wheelblast, Airblast and Peening Discussions Wheelabrator Airblast and Wheelblast Forum For Blasting Professionals
• Cut Wire Shot Images