Characterization of microscopic residual stresses: A review

•An overview focusing on the characterization of micro-residual stress is presented.•Advances in testing techniques including non-destructive and micro-destructive methods are summarized.•Challenges in practice and perspectives concerning the further improvement of characterization are proposed. Residual stresses are important factors affecting the performance and lifespan of components, among which the influence of micro-residual stress on crack propagation and fatigue property is no less than that of macro-residual stress, so it cannot be underestimated in materials design, forming and processing, life prediction as well as failure analysis. However, the accurate characterization of micro-residual stress is still facing many challenges, and the interaction between micro-residual stress and microstructures has yet been clearly understood. In view of this, the latest progress in the characterization methods such as electron backscattered diffraction, focused ion beam-digital image correlation, nanoindentation, among others, in mapping the micro-residual stress is summarized, including the testing principle, scope of application, measurement accuracy, along with the corresponding limitations. In addition, the trends for techniques in probing micro-residual stress are also proposed with the aim of extending extra vision for further improving the measurement accuracy and systematic research on residual stresses on microscopic scale.