Iranian Journal of Manufacturing Engineering

Iranian Journal of Manufacturing Engineering

Effect of aging treatment on the work hardening behavior of AA6061 alloy

Document Type : Original Article

Author
Mehdi Shaban Ghazani
Department of Materials Science Engineering, University of Bonab, Bonab, Iran
10.22034/ijme.2025.514910.2069
Abstract
Aluminum alloy 6061 is widely used in engineering applications due to its favorable mechanical properties and heat treatability. In this study, the effect of natural and artificial aging on the work hardening behavior of this alloy was investigated. For this purpose, the samples were first solution annealed at 520°C and then rapidly quenched in water. The artificially aged samples were kept at 160°C for 2 to 20 hours and the natural aged samples were kept at room temperature for 1 to 10 days. Tensile testing was performed according to ASTM E8 standard and the work hardening behavior was analyzed using Holloman and Crussard-Jaoul (CJ) relationships. The results showed that with increasing artificial and natural aging time, tensile strength increases from 193 and 163 MPa to 283 and 217 MPa, respectively, while the elongation at break decreases from 21% and 34% to 12% and 14.4%, respectively. The average work hardening exponent also decreased from 0.14 to 0.09 with increasing artificial aging time. CJ analysis showed that the work hardening behavior of the alloy occurs in three distinct stages: the first stage with high work hardening rate, the second stage with a significant decrease in strain hardening, and the third stage with a negative value (n < 0) resulting from the recovery of the dislocation structure. These results indicate that although the aging process leads to an increase in strength, the work hardening and ductility of the alloy are significantly reduced due to the saturation of dislocation density and coarsening of precipitates. It was also found that natural aging maintains higher work-hardening capacity compared to artificial aging, which is due to the formation of finer and more effective precipitates in inhibiting dislocation movement.
Keywords
AA6061 Alloy
Tensile Test
Work Hardening Exponent
Natural Aging
Artificial Aging
CJ Analysis
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