A New Method for Nondestructive Evaluation of Mechanical Properties Using Instrumented Indentation Technique

The development of the instrumented indentation test (IIT), which gives accurate measurements of the continuous variation in indentation load as a function of depth, has paved the way to assessing tensile properties and residual stress in addition to hardness by analyzing the indentation load-depth curve. In this study, analytic models and procedures are presented for evaluating tensile flow properties and residual stress states using IIT. Tensile properties were obtained by defining representative stress and strain beneath the spherical indenter. The evaluation of residual stress is based on the concepts that the deviatoric stress part of the residual stress affects the indentation load-depth curve, and that analyzing the difference between the residual stress-induced indentation curve and the residual stress-free curve permits evaluation of the quantitative residual stress in a target region.