A numerical approach for determination of flow curve and evaluation of frictional behavior of AZ61 magnesium alloy under elevated temperature forming conditions

• Ring test can determine friction factors of AZ61 Mg alloy for all forming conditions.
• Friction factor variations with the strain rate and temperature are linear.
• The present material model can predict flow behavior of AZ61 alloy very well.
• At high friction, temperature and strain rate have more effects on sigmoid curves.

The ring compression test can be used for evaluation of both the interfacial friction and the flow curve of a material at the same time. Hence, this test is employed in the paper to simultaneously determination of the flow stress and the friction factor for AZ61 alloy. This alloy can be utilized for manufacturing extruded parts with a higher production rate, compared with other magnesium alloys. Using an iterative procedure and by means of the numerical sigmoid and calibration curves, the flow curve and interfacial friction factor of the magnesium alloy are determined. This was carried out for various temperatures and strain rates. In addition, the flow behavior of as-cast AZ61 is modeled employing an exponential function. It was found that the predictions of the mathematical model were encouragingly very good. Moreover, the influences of the temperature on the interfacial friction condition and numerical sigmoid curves were greater than those of the strain rate.