Effect of ecap and subsequent heat treatments on microstructure and mechanical properties of 2024 aluminum alloy

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Tezin Türü: Yüksek Lisans

Tezin Yürütüldüğü Kurum: Orta Doğu Teknik Üniversitesi, Mühendislik Fakültesi, Metalurji ve Malzeme Mühendisliği Bölümü, Türkiye

Tezin Onay Tarihi: 2008

Öğrenci: EBRU SARALOĞLU

Danışman: TAYFUR ÖZTÜRK

Özet:

Severe plastic deformation (SPD) results in ultra-fine grain sizes in metals and alloys. Equal channel angular pressing (ECAP) is one of the special SPD methods aiming to introduce high plastic strains into the bulk materials without changing their cross section. ECAP results in improvement in hardness and strength while still satisfying acceptable ductility level. The combined effects of ECAP and subsequent heat treatments, i.e. post-aging and post-annealing, on the microstructure and hardness of the 2024 aluminum alloy were investigated. An ECAP die with 120˚ channel angle was constructed. Subgrain formation, increase in dislocation density and dislocation tangling were observed after ECAP, and subgrain growth was detected after post annealing. The specimens revealed higher hardness values after ECAP at room temperature, and further increase in hardness was observed following post-aging at 80˚C, 100˚C and 190˚C. Effect of the aging temperature on the deformed specimens was investigated, and the aging behaviors of the severely deformed and undeformed samples at 190˚C were compared.