Identification, using nanoindentation tests, of mechanical behaviour of a 2C22 steel presenting a residual stress state

AbstractThis work investigates, using nanoindentation tests, mechanical behavior (stress-strain curve and residual stress state) of a 2C22 steel sample in which a residual stress state has been introduced. A cylindrical sample has been especially developed in order to introduce a controlled residual stress state at the center of the specimen. The size of the sample allows us to perform nanoindentation tests in the different zones using two indenters (Berkovich and Cube Corner) without any additional preparation. Nanoindentation tests have been performed on samples with and without residual stresses. Analysis of experimental load – displacement curves obtained on the virgin sample, coupled with 2D and 3D numerical simulations of indentation, allows, using inverse models, the determination of the stress – strain curve of the virgin material. Analysis of experimental tests conducted on the strained sample, using stress effect removal models and the virgin sample properties, allows the identification of the magnitude of residual stresses introduced. These results are validated by measurements using X-ray diffraction and a finite element modeling of the prepared sample