Novel approaches to determine residual stresses by ultramicroindentation techniques: application to sand blasted austenitic stainless steel

Abstract

This research addresses the determination of residual stresses in sandblasted austenitic steel by ultramicroindentation techniques using a sharp indenter, whose sensitivity to residual stress effects is said to be inferior to that for spherical ones. We propose the introduction of an angular correction in the model of Wang et al. that relates variations in the maximum load to the presence of residual stresses. Likewise, the contribution to hardness of grain size refinement and work hardening, developed as a consequence of the severe plastic deformation during blasting, is determined to avoid overestimation of the residual stresses. Measurements were performed on polished cross sections along a length of several microns, thus obtaining a profile of the residual stresses. Results show a good agreement with those obtained by synchrotron radiation on the same specimens, which validates the method and demonstrates that microindentation using sharp indenters may be sensitive to the residual stress effect.