Hot Deformation Behaviour and Processing Maps of an as-Cast Mg-6.8Y-2.5Zn-0.4Zr Alloy

Abstract:

Deformation behavior of an as-cast Mg-6.8Y-2.5Zn-0.4Zr alloy during plane strain compression was characterized in present work by high-temperature testing. Based on the experimental data, the values of strain rate sensitivity, efficiency of power dissipation and the instability parameter under the condition of various hot working parameters were investigated. Processing maps were established by superimposing the instability map over the power dissipation map, this being connected with microstructural evolution analysis in the hot deformation processes. Accompanied microstructure characterization of the binary α-Mg/ Long Period Stacking Ordered (LPSO) microstructure reveals that the flow behavior is related to the deformation mechanisms. At lower temperatures (350 – 400 °C) formation of kink bands is observed, which normally occur when deformation twinning is inhibited and other slip systems are strongly hindered by the complex LPSO structures. Dynamic recrystallization (DRX) was initiated at higher temperatures above 400 °C, influencing the softening behavior of the material significantly. DRX was the main softening mechanism when deformation takes place at 500 °C and the kink band deformation decreased.

• Periodical: Materials Science Forum (Volume 949)
• Pages: 57-65
• DOI: https://doi.org/10.4028/www.scientific.net/MSF.949.57
• Online since: March 2019
• Authors: Madlen Ullmann*, Matthias Schmidtchen, Kristina Kittner, Thorsten Henseler, Rudolf Kawalla, Ulrich Prahl
• Keywords: Dynamic Recrystallization, Flow Curve, LPSO Phase, Processing Map

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