Abstract

In many engineering applications the elastic-limit loads for members are increased by overloading the members until inelastic deformation occurs in regions of peak stresses. The extent of the inelastic deformation may be of the order of magnitude of the elastic-limit strain in such members as overstrained beams and autofrettaged thick-walled cylinders. An increase in the elastic-limit loads for these members is possible because of the beneficial macroscopic (measurable) residual stresses resulting from the inelastic deformation. However, the full theoretical beneficial effect of the residual stresses is never realized since they are reduced by the inelastic deformation caused by the Bauschinger effect which occurs when the member is unloaded. This investigation was undertaken to determine whether the full benefit of the macroscopic residual stresses could be retained by aging the member while loaded, and in this way eliminate the Bauschinger effect before its detrimental influence could occur. Tests were conducted on beams of rectangular cross section made from annealed mild (SAE 1020) and high-carbon (rail) steels. An aging treatment of 180 F for 20 hr was found to be sufficient to remove practically all of the Bauschinger effect in the mild steel but was not sufficient to remove all of the Bauschinger effect in the high-carbon steel.

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