Monotonic and cyclic behaviour of cast and cast-forged AZ80 Mg
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Date
2017-11
Authors
Gryguc, Andrew
Shaha, Sugrib K.
Behravesh, Seyed Behzad
Jahed, Hamid
Wells, Mary
Williams, Bruce W.
Su, X.
Advisor
Journal Title
Journal ISSN
Volume Title
Publisher
Elsevier
Abstract
Tensile and strain-controlled fatigue tests were performed to investigate the influence of forging on the performance of cast AZ80 magnesium alloy. The obtained microstructural analysis showed that the as-cast AZ80 magnesium alloy has dendritic α-Mg phase with eutectic Mg17Al12 morphology and a random texture. In contrast, the forged samples showed refined grains and a strong basal texture. During tensile testing, a maximum yield and ultimate tensile strength of 182 MPa and 312 MPa were obtained for the forged samples, representing increases of 121% and 33%, respectively, from the as-cast condition. At the same time, a significant improvement (73%) in ductility was obtained in forged samples. It was also observed that the forged samples achieved comparatively longer fatigue life under strain-controlled cyclic loading. Analysis of the fracture surfaces showed that a cleavage-type morphology was typical for the as-cast samples, while the occurrence of dimples and other evidence of plastic deformation were identified in the fracture surfaces of the forged specimens, indicating a more ductile response. Forging caused grain refinement and texture modification, both of which enhance alloy performance by improving strength and ductility, and leading to longer fatigue life. Strain and energy-based models were investigated for their suitability to predict the life of the forged material. Both the Smith-Watson Topper and the Jahed-Varvani energy-based models gave reliable life prediction.
Description
The final publication is available at Elsevier via https://doi.org/10.1016/j.ijfatigue.2017.06.038 © 2017. This manuscript version is made available under the CC-BY-NC-ND 4.0 license http://creativecommons.org/licenses/by-nc-nd/4.0/
Keywords
AZ80, Forging, Texture, Fatigue characterization, Fracture, Fatigue modeling