Electronics Incorporated - The Shot Peener - Shot Peening Library
Title: Residual Stresses in Shot Peened Components
Author:
Source: TSP, Vol 18/Issue 4 Winter 2004
Publication year 2004
Document number: 2004003
Number of pages: 8
Abstract:
Shot peening of components produces a ‘magic skin’ containing compressive residual macrostress.
This skin has a thickness that is largely determined by the size of the shot particles that
have been used. The level of compressive residual stress in the skin is a large fraction of the
yield strength of the as-peened surface material. Residual and applied stresses superimpose
themselves, so that compressive surface residual stresses offset tensile applied surface stresses.
It is that lowering of net surface stress that improves the service performance of shot peened
components.
Residual stresses are produced whenever inhomogeneous plastic deformation is applied to a
component. Shot peening is a prime example of inhomogeneous plastic deformation. Peening
involves tensile plastic deformation of a surface layer - produced as the sum of numerous
indentation expansions. Compressive residual stresses are generated at the surface because of
this tensile deformation. Peening can impose huge amounts of deformation without cracking
because of the hydrostatic compression that is involved. Gold has a tensile ductility of 40% but
can be hammered until it is almost transparent. The imposed stored energy is so great, however,
that gold leaf (normal M.Pt. 10640C) will melt in one’s hand.
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This page last revised: 04/24/2008