Residual stress is stress present after the external loading that produced it has been removed. Different regions can acquire incompatible preferred shapes through nonuniform plastic deformation or thermal expansion. Because the regions must still fit together, elastic deformation balances those mismatches and leaves an internal stress field.
A free specimen can therefore have zero resultant external force while containing regions in tension and compression. For example, cooling different parts at different rates can leave different permanent strains, even after their temperatures become equal. Cutting the specimen releases some constraints, and the resulting shape change can reveal the stored stress. In a simple traction-free static body with no body force, the residual stress must satisfy internal force balance and zero surface traction. It affects later loading because the applied stress adds to a pre-existing field rather than starting from zero everywhere.
Residual stress refers to the internal stresses that remain in a material even after the original cause of the stresses has been removed. These stresses can arise during manufacturing processes, such as welding, casting, machining, or upon solidification of a material. They can also develop over time due to various factors, including phase transformations, thermal cycles, and mechanical loading. Residual stresses can significantly affect the performance of materials and components, influencing their mechanical properties such as fatigue resistance, fracture toughness, and dimensional stability.
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