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Low cycle fatigue behavior of AZ31B extrusion at elevated temperatures

•Asymmetric hysteresis loop at room temperature changed to a symmetric one at 200 °C.•Hysteresis loops at 200 °C exhibit no inflection point.•Twinning-detwinning mechanisms do not govern the plastic deformation at 200 °C.•Mean stress diminishes and cyclic softening occurs at the elevated temperature...

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Bibliographic Details
Published in:International journal of fatigue 2020-10, Vol.139, p.105803-14, Article 105803
Main Authors: Jabbari, A.H., Sedighi, M., Jahed, H., Sommitsch, C.
Format: Article
Language:English
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Summary:•Asymmetric hysteresis loop at room temperature changed to a symmetric one at 200 °C.•Hysteresis loops at 200 °C exhibit no inflection point.•Twinning-detwinning mechanisms do not govern the plastic deformation at 200 °C.•Mean stress diminishes and cyclic softening occurs at the elevated temperatures.•Jahed-Varvani model offers the most promising predictions at all the temperatures. Fully-reversed strain-controlled tests have been performed on AZ31B magnesium alloy extrusion at room temperature, 100 °C, and 200 °C. Different fatigue life prediction models including Coffin-Manson-Basquin, Smith-Watson-Topper, and Jahed-Varvani were applied to predict the fatigue life. According to the shape of the hysteresis loops at half-life, by increasing the test temperature to 200 °C, the asymmetric behavior of the magnesium changed to a symmetric shape. No inflection point can be observed in the loops at 200 °C, the mean stress decreases dramatically, and the cyclic softening occurs. Among different models, Jahed-Varvani as an energy-based approach offers the most promising predictions at all the temperatures.
ISSN:0142-1123
1879-3452
DOI:10.1016/j.ijfatigue.2020.105803