EFFECT OF THERMO-MECHANICHAL TREATMENTS ON THE MECHANICAL BEHAVIOUR OF AL-Cu AND AL-Mg-Si ALLOYS

Document Type : Original Article

Authors

1 Assistant Lecturer, dep. of materials science and technology, MTC.

2 Dr. materials science and technology dpt., MTC.

3 Prof. materials science and technology dpt., MTC.

Abstract

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%.

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