Yield Locus of a Cold Rolled and Solution Treated Nimonic-263 Alloy Sheet, Determined Using Asymmetrical Knoop Micro Hardness Indenter

Abstract

The Von Mises or perhaps the Tresca criterion is adequate for predicting the onset of yielding under combined stress loading for isotropic materials. However, this prediction is not so straight forward for anisotropic materials in which the magnitude of tensile and compressive yield stresses are different along the different orientations. Such directionality in yield behavior of anisotropic materials may strongly depend on the nature and degree of crystallographic texture. Texture driven yield surfaces are the representatives of the states of plane stress (tension–tension, tension–compression and compression–compression) in thin wall tube by externally applied forces and internal pressure. The applications of yield surfaces are far too wide and particularly have direct relevance to the metal forming, such as cold rolling. A simple procedure based on Knoop microhardness measurements has been proposed in the literature for determining the plane stress yield surface of the sheet materials. In the present study, an attempt has been made to describe this technique and the procedure to determine the yield locus using Knoop microhardness indenter and compare the yield surface anisotropy determined with the experimentally observed tensile properties in the in-plane directions and thus establish the usefulness of this technique in case of a cold rolled and solution treated Nimonic-263 alloy sheet of 1.0 mm thickness in solution treated condition.