Peening - Residual Stress

Residual Stress

Plastic deformation from peening induces a residual compressive stress in a peened surface, along with tensile stress in the interior. This stress state resembles the one seen in toughened glass, and is useful for similar reasons.

Surface compressive stresses confer resistance to metal fatigue and to some forms of corrosion, since cracks will not grow in a compressive environment. The benefit comes at the expense of higher tensile stresses deeper in the part. However, the fatigue properties of the part will be improved, since the stresses are normally significantly higher at the surface in part due to surface imperfections and damage.