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Quasti-Static and Dynamic Response, and Texture Evolution of Two Overaged Al 7056 Alloy Plates in T761 and T721 Tempers: Experiments and Modeling

Published

Author(s)

Angela Y. Ku, Akhtar S. Khan, Thomas H. Gnaupel-Herold

Abstract

The thermo-mechanical behavior and texture evolution of two overaged Al 7056 alloy plates, in near peak strength (T761) and near peak aged (T721) tempers, are measured over a wide range of strain rates (10-4 – 3 x 103 s-1) and temperatures (22 – 300°C) under uniaxial tension and compression along the thickness direction, i.e. normal to the plate surface. A detailed study of the initial microstructure reveals an increase in grain size and decrease in density of precipitates, as the alloy is aged from the T761 to T721 temper; which in turn affects the flow stress and strain hardening behavior. Differences in flow strength and strain hardening rate, as well as tension-compression asymmetry in the two tempers, are apparent at the lower temperatures (22°C & 100°C) and decrease significantly at the higher temperatures (200°C & 300°C). Furthermore, initial texture measurements show a strong texture gradient along the normal direction (ND) of the plate. This texture gradient affects the ultimate stress insignificantly. However, it does have a considerable effect on the failure strains of specimens taken from different locations through the thickness. A transition from shear fracture at and below 200°C to cup and cone fracture mode above 200°C is observed in tension. Both tempers exhibit a positive strain rate sensitivity (SRS) that is dependent on temperature and strain rate. A sharp decrease in flow stress is found at 300°C. The Khan-Liu (KL) model is modified to correlate with the measured thermo-mechanical responses of the two tempers over the studied, wide range of strain rates and temperatures. There is a close correlation between simulated and observed results.
Citation
International Journal of Plasticity
Volume
130

Keywords

7XXX series aluminum alloys, Precipitation hardening, Strain rate sensitivity, Texture evolution, Constitutive modeling

Citation

Ku, A. , Khan, A. and Gnaupel-Herold, T. (2020), Quasti-Static and Dynamic Response, and Texture Evolution of Two Overaged Al 7056 Alloy Plates in T761 and T721 Tempers: Experiments and Modeling, International Journal of Plasticity, [online], https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=928826 (Accessed July 2, 2022)
Created December 31, 2019, Updated October 12, 2021