A Method to Characterize Residual Stresses Induced by Machining

The modeling of residual stresses induced by drilling remains an issue. Indeed, even if some models are under development, their validation is limited by the absence of universal characterization method of residual stresses inside the hole. This paper aims at presenting a procedure to characterize the residual stress profile induced by drilling. The principle is based on the preparation of a reference sample that has been pre-heat treated in order to remove bulk residual stresses without modifying the microstructure. Then the sample is instrumented with strain gauges before being cut in two parts. This enables on one hand to estimate the elastic recovery after the cut and on the other hand to provide an easy access to the investigated surface. Finally a standard X-Ray diffractometer and an electropolishing technique are combined to estimate residual stresses profiles in two directions (circumferential and axial directions). Some numerical analyses are also performed to estimate stress relaxation during thermal treatment and during sample cutting to give a better interpretation of measurements.