Prediction of Flow Stress for Superplastic Tension Deformation

Abstract:

With the development of numerical calculation and precision forming, constitutive equations are required to possess high accuracy and good reliability, rather than simplicity of mathematical form. Due to simple algorithm and constant parameters, the conventional constitutive models can not be suited to describing superplastic flow behavior which represents complex responses with a large strain. In this study, through surface fitting on experimental data from tension tests performed over a wide range of strain rates, tensile velocities and loads, an empirical approach was proposed to establish constitutive equation for complex superplastic behavior of Zn-5%Al alloy at 340 °C. The empirical constitutive equation not only represents the strain dependence and the strain rate dependence of stress, but also reflects the coupling effects of strain and strain rate on stress, which can not be achieved by traditional models. A comparison between the predicted flow stresses and the experimental data verified that the empirical constitutive equation has high accuracy and good reliability on modeling superplastic flow behavior of Zn-5%Al alloy at 340 °C in a wide range of strains 0~2.5 and strain rates 7.0×10^-5~8.0×10^-2 s^-1.

• Periodical: Advanced Materials Research (Volumes 941-944)
• Pages: 1501-1504
• DOI: https://doi.org/10.4028/www.scientific.net/AMR.941-944.1501
• Online since: June 2014
• Authors: Zhi Ping Guan*, Ming Wen Ren, Pin Kui Ma, Po Zhao
• Keywords: Constitutive Equation, Flow Stress, Material Modeling, Material Parameter, Superplasticity

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