Modeling the strain hardening response of low SFE FCC alloys

A mathematical description has been proposed to capture the complex four-stage strain hardening behavior of low stacking fault energy (SFE) polycrystalline fee metallic alloys that deform plastically by both slip and twinning mechanisms. Tt has been demonstrated that the proposed model is capable of predicting fairly accurately the measurements reported previously on the strain-hardening responses of several fee alloys, including brasses (varying Zn content), stainless steels, and a Co-Ni superalloy, deformed to large strains in simple compression tests. For a set of alloys with a wide range of SFEs but with roughly the same initial average grain size, it was demonstrated that only one material parameter in the proposed model was influenced by the stacking fault energy of the alloy; all other parameters normalized by the shear modulus of the alloy maintained approximately the same value. The parameters that are strongly influenced by the grain size have been identified for these alloys. A physical interpretation has been provided for the various material parameters in the proposed strain-hardening model. (C) 1998 Elsevier Science Ltd.. All rights reserved.