Investigation of mechanical property changes after mig welding of (7XXX) series aluminum alloys

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Tezin Türü: Yüksek Lisans

Tezin Yürütüldüğü Kurum: Orta Doğu Teknik Üniversitesi, Rektörlük, Rektörlük, Türkiye

Tezin Onay Tarihi: 2016

Öğrenci: SENA OKAY

Eş Danışman: CANER BATIGÜN, BİLGEHAN ÖGEL

Özet:

There is an increasing demand for aluminum alloys not only in aerospace industry but also in automotive industry due to its low density. Welding is the most effective and commonly used joining technique in those industries, therefore, aluminum welding plays an important role. 7039 aluminum alloy, is a high strength alloy and it is suitable for armor applications. Like other aluminum alloys, after MIG welding, remarkable decrease in strength is observed and therefore applications are restricted. The aim of this study is to investigate the mechanical property changes after welding for different weld groove shapes of 7039 alloy and to recover the strength in HAZ by performing post weld heat treatment. Different weld groove shapes affected the heat input since the area subjected to heat changed depending on the angle of the groove. EDX analyses were conducted in order to understand the changes in elemental distribution. By performing post weld heat treatments, hardness for each sample increased in HAZ. However UTS and yield strength in several samples were decreased after prolonged solutionizing heat treatments. vi On the other hand, welding defects such as lack of fusion affects the mechanical properties negatively. In 45° X shaped weld grooved sample, the most effective results were obtained. After post weld heat treatment the hardness values increased around 10%.