Novel implementations of relaxation methods for measuring residual stresses at the micron scale

The advent of dual-beam focused ion beam - field emission gun scanning electron microscope (FIB-SEM) imaging and milling systems in combination with digital image correlation (DIC) analysis has made it possible to make very fine excisions and to record the resulting displacements with nanometre precision. This has led to novel implementations of macroscale residual stress measurement methods to the microscale, for example, micro-slotting, micro-hole drilling and so on. This review article outlines the different methods for residual stress mapping at the micron scale highlighting their relative merits and limitations with the aim of guiding the user towards the most appropriate techniques for a given application. These open new possibilities for residual stress measurement not just at the continuum scale but even for mapping stresses within grains. In addition, recent advances in milling throughput promised by new dual-beam plasma focused ion beam systems promise to help bridge the gap between the conventional macroscale methods and their micron-scale counterparts.