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Shot peening is a cold working process used to increase the fatigue life of metal parts. Parts are bombarded with round steel, glass, or ceramic shot under controlled conditions to induce a stressed surface layer in compression. This surface layer inhibits the formation of tiny surface cracks which give way to fatigue failure. The compressive stresses are also beneficial in increasing resistance to corrosion fatigue and stress corrosion cracking. Shot peening can also be used to control porosity and for surface texturing.

What is Shot Peening?

Shot peening is primarily used to increase fatigue life by bombarding the surface of the part with small spheres of uniform media that induce compressive stresses. The Shotpeen Process is similar to repeatedly and evenly hammering a surface with a ball peen hammer.

Shot peening is used primarily to prevent fatigue failures that originate on the surface of a part. Small indentations or dimples form on the surface, and the metal immediately below those indentations tries to resist further compression, creating what’s known as residual compressive stress. Fatigue cracks generally will not initiate in a compressively stressed area, so part life is extended.

Residual Compressive Stress

Shot peening is a process of inducing RESIDUAL COMPRESSIVE STRESS on the surface layer of metal parts. As the stream of shot is propelled at the surface of the part an impression is created. These impressions create the Residual Compressive Stresses at and slightly beneath the surface. This process enhances fatigue life and/or stress corrosion that it may be exposed to once in service.

Some of the common applications that benefit from Shot peening include; springs, gears, shafts and connecting rods and various transmission components.


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