S. I. Rokhlin, The Ohio State University, Columbus, OH; P. B. Nagy, University of Cincinniti, Cincinnati, OH; M. P. Blodgett, US Air Force Research Laboratory, Wright-Patterson AFB, OH

Summary:

Nondestructive evaluation of residual stresses and of residual stress relief in service conditions has great significance for reliability of turbine engine components. It is important to achieve better fundamental understanding of relations between nondestructive signature and material properties such as hardness, plasticity, cold-work and residual stress. In this work a nanoindentation technique is explored to determine the micromechanical properties and their relation to different levels of cold work in Ni based superalloys. Also the relations between inhomogeneities of electrical conductivity in nickel-base superalloys and microscale elasto-plastic properties have been investigated. Results of instrumented nanoindentation measurements of hardness and effective modulus in different Ni based superalloys are reported as it related to above stated applications. Also our resent progress on development of an approach to determine local mechanical properties (Young’s modulus E, yield stress σ_y and strain hardening exponent n) from nanoindentation tests as is done from uniaxial tensile/compression experiments is going to be reported. This is based on inversion of nanoindentation data and elasto-plastic properties reconstruction by utilizing finite element simulations and developed explicit scaling functions.