Relationship between strength and uniform elongation of metals based on an exponential hardening law

Abstract

An exponential strain-hardening (ESH) model for single phase metals was established and well verified by systematic experiments on Cu-Al alloys in an earlier study. In this report, several additional significant revelations will be documented for the tensile behaviors of several typical metals. Firstly, a unified interpretation of the well-known five strain-hardening stages is developed by correlating the characteristics of each stage with the parameter n that relates to the dislocation annihilation behavior. Secondly, quantitative relationships among the yield strength (YS), ultimate tensile strength (UTS) and uniform elongation (UE) are established and verified using the tensile experimental results for Cu-Al alloys. Thirdly, the two general principles of the synchronous improvement of strength and uniform elongation (SISUE) effect, such as the composition adjustment and microstructure optimization, are quantitatively revealed by the composition parameter n and a microstructure type parameter η. Two typical trends of the true UTS-UE curves and two kinds of characteristic strengths are quantitatively revealed and confirmed by the relevant experimental data. Finally, a prediction model of tensile properties is proposed and a corresponding procedure is displayed, which is further verified by the tensile experimental results for Cu-Al alloys. These applications further support the validity and significance of the ESH model.