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A constitutive model to describe high temperature flow behavior of AZ31B magnesium alloy processed by equal-channel angular pressing
Date Issued
29-04-2019
Author(s)
Arun, M. S.
Indian Institute of Technology, Madras
Abstract
Equal channel angular pressing (ECAP) is a well-known process for developing an ultrafine-grained microstructure in metals and alloys. In this study, the hot deformation behavior of an AZ31B Mg alloy has been evaluated as a function of ECAP passes and processing routes. Specimens were subjected to three passes of ECAP using a die angle of 120° using processing routes BC and C. Isothermal hot compression testing at strain rate ranging from 0.01 to 10 s−1 and temperatures ranging from 250 to 400 °C were conducted and flow curves generated. The flow curve data generated were fitted to standard constitutive equations used to describe hot working behavior and the activation energies were determined. It was observed that the activation energies for hot deformation decreased after ECAP and this can be related to the grain refinement due to the ECAP process. Activation energy decreased from 161.6 kJ/mol in the annealed condition (grain size: 29 μm) to 145.3 kJ/mol for route 3BC (grain size: 4.7 μm) and 132.3 kJ/mol for route 3C (grain size: 4.9 μm). Equations for predicting the peak flow stress for various ECAP passes has been generated using the Zener Hollomon parameter and these are in agreement with the experimentally observed values.
Volume
754