Yield locus of 70/30 brass sheet metals

Abstract

Yield stresses in uniaxial tension, biaxial tension and close to plane-strain tension tests were determined in a 70/30 brass sheet metal. These results were compared to those obtained by Wagoner [ Metall. Trans. A13, 1491 (1982)] and by Vial et al. [ Int. J. Mech. Sci. 25, 899 (1983)]. Biaxial tension yield stress was greater than uniaxial tension yield stress, and it could be predicted with exponents 1.66–1.75 of Hill's (1979) yield criterion. Close to plane-strain tension tests produced lower strain hardening than uniaxial tension tests; both yield stresses became very close at true strains greater than 0.1. This effect required an increase of the exponent of Hill's (1979) yield criterion, to values greater than 2.0. The set of results obtained by the present research could not be adequately described by the simplified form (Case 4) of Hill's (1979) yield criterion. A study of the evolution of crystallographic textures with strain, along different loading paths, should be performed in order to gain a better understanding of the change in shape of the yield locus of 70/30 brass sheet metals.