Iranian Journal of Materials Science and Engineering

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Hot deformation behavior of a medium Cr/Mn Al6061 aluminum alloy was studied by isothermal compression test at temperatures range of 320 to 480 °C and strain rates range of 0.001 to 0.1 s −1. The true stresstrue strain curves were analyzed to characterize the flow stress of Al6061. Plastic behavior, as a function of both temperature and strain rate for Al6061, was also modeled using a hyperbolic sinusoidal type equation. For different values of material constant α in the range of 0.001 to 0.4, values of A, n and Q were calculated based on mathematical relationships. The best data fit with minimum error was applied to define constitutive equation for the alloy. The predicted results of the proposed model were found to be in reasonable agreement with the experimental results, which could be used to predict the required deformation forces in hot deformation processes

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Till now, different constitutive models have been applied to model the hot deformation flow curves of different materials. In this research, the hot deformation flow stress of API X65 pipeline steel was modeled using the power law equation with strain dependent constants. The results was compared with the results of the other previously examined constitutive equations including the Arrhenius equation, the equation with the peak stress, peak strain and four constants and the equation developed based on a power function of Zener-Hollomon parameter and a third order polynomial function of strain power a constant number. Root mean square error (RMSE) criterion was used to assess the performance of the understudied models. It was observed that the power law equation with strain dependent constants has a better performance (lower RMSE) than that of the other understudied constitutive equations except for the equation with the peak stress, peak strain and four constants. The overall results can be used for the mathematical simulation of hot deformation processes