Residual Stress (Forming)

Definition

Residual stress is the stress field inside a material that has been subjected to permanent deformation beyond its limit of plasticity or remaining elastic stresses in a workpiece, e.g., due to nonuniform plastic deformation and/or significant temperature gradients.

Theory and Application

Introduction

If the plastic deformation is uniaxial, such as that induced in a tensile test, and the material is isotropic without the initial stress field, the stress of a permanently strained material can recover to its initial state without residual stress. The stress–strain curve in Fig. 1explains elastic recovery in such a case. The material after uniaxial tensile deformation can fully recover after unloading the imposed external force, because its stress is uniform without a gradient, and it can deform freely in the opposite direction to that of loading. However, in general, every point in a material after loading or forming has a stress gradient and cannot deform freely during...