Stress Relaxation Kinetics and Post-Deformation Microstructural Features in Aged Aluminum Alloy AA6061
DOI:
https://doi.org/10.71146/kjmr884Keywords:
Aging Heat Treatment, XRF, Stress Relaxation, Activation Energy, SEM, Microsturcture Fractograph AnalysisAbstract
The Stress relaxation behavior of Aluminum 6061 alloy artificially aged at 200°C for different time intervals was examined using Tensile Testing Machine at a constant strain rate.The Stress Relaxation rates was determined at strain intervals of about 0.5% until fracture.It was found that stress relaxation curves were logarithmic, except at large ’t’ when they flattened .The stress relaxation rate was found to increase with initial stress levels and aging time upto 6hr, while the 8hr- aged sample exhibited a decline in stress relaxation rate.Similarly activation energy for stress relaxation increased from 0.85eV to 1.46eV upto 6hr of aging and decreased from 1.46eV to 1.29eV in the overaged specimen.A progressive increase in activation energy correlates with fractograph analysis using SEM.The Variations in stress relaxation rates and activation energy in the case of aged and overaged specimens were due to changes in slip processes responsible for work hardening. SEM fractographs showed a transition from ductile dimple fracture in unaged samples to a brittle fracture mode in over-aged specimens. These results highlight the critical role of microstructural evolution in dictating the stress relaxation behavior of AA6061 alloy, providing valuable insights into optimizing its performance in applicatons where long term mechanical stability is required.
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Copyright (c) 2026 S. Tabinda Munib , Hafsa Iftikhar , Faiza Yousaf (Author)
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