Challenges and Progress in Residual Stress Evaluation and Analysis at the Nanoscale

Abstract

Residual Stresses are an aspect of material state that is complex in many different respects. As any stress quantity, it has multi-component tensor nature, so that at each point up to 6 components need to be determined. Moreover, in contrast with ‘live’ stresses, residual stresses (RS) cannot always be determined by tracking their evolution from an initial state. Furthermore, RS are scale-dependent, so that if the resolution (gauge volume) of the measurement is changed, so does the perceived stress state. In the context of RS ‘measurement’, conventional classification into Type I, II and III (macro-, micro- and nano-scale stresses) is often used, but the intricate relationship between these quantities remains insufficiently well understood. Finally, the interaction of RS with material processing and service behaviour introduces further associated complexities, and deserves additional discussion.