Document Type : Original Article
Assistant Lecturer, dep. of materials science and technology, MTC.
Dr. materials science and technology dpt., MTC.
Prof. materials science and technology dpt., MTC.
This investigation was carried out on two heat treatable aluminum alloys type-2014 (Al-Cu) and type-6082 (Al-Mg-Si) in order to evaluate their mechanical response against cold plastic strain either prior to or between the stages of aging. Standard flat specimens of the first alloy having a thickness of 3 mm were solution treated at 500°C for 1 hr followed by quenching in water then immediately subjected to different percentages of cold plastic strain either prior to, or/and between the stages of a double aging cycle. The first aging stage was carried out at 140°C for 55 hrs while the second one at 170°C for 5 hrs. The specimens of the second alloy having the same thickness were also solution treated at a higher temperature of 535°C for 1 hr and was also subjected to the same type of thermo-mechanical cycles, where aging of the first stage was done at 100°C for 15 hrs and at 180°C for 5 hrs in the second stage. The obtained results showed that, the application of 10% plastic strain prior to aging conjointly with 12% plastic working between the stages of double aging provide the utmost hardening effect to the Al-Cu alloy type-2014 by nearly doubling its strength. Moreover, the Al-alloy type-6082 showed a lower response to hardening compared with the Al-alloy type-2014. The application of 10% cold plastic strain prior to aging conjointly with 5% cold plastic strain between the stages of double aging increases the proof strength by 80% and decreases the ductility only by about 27%.