Experimental and numerical investigation of the mechanical behavior of materials with nanoindentation method

In this study, micro/nano mechanical properties of high-strength dual-phase steels used in automotive and armor steels were investigated by nanoindentation method and compared with the results obtained from conventional methods. In addition, the changes in mechanical properties of spherical copper powders by sintering after compression were investigated. Nanoindentation and X-ray diffraction (XRD) analyzes were performed on armor steels subjected to ballistic tests and automotive steels subjected to three-point bending test. Nanoindentation measurements were performed with a sharp triangular pyramid (Berkovich) tip. Force-displacement curves were used to calculate residual stresses with empirical relations, as well as the hardness and modulus of elasticity values obtained from nanoindentation measurements. These values were found to be in good agreement with the residual stress measurements obtained from the XRD - sin2ψ method. Microstructural analysis optical, scanning electron, atomic force microscope (AFM) were also performed on these materials. In doctoral thesis, it was also demonstrated that nanoindentation, XRD, residual stress are useful methods to evaluate the distribution of mechanical properties of undeformed - deformed regions after three-point bending test and ballistic tests.