Utilization of friction stir processing to improve the mechanical properties of gas metal arc welded 5083 aluminum alloy plates

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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: 2016

Öğrenci: SHAHIN TAKHT FIROUZEH

Danışman: CEMİL HAKAN GÜR

Özet:

Fatigue failure of the welded structures is a major problem in engineering applications. It is known that the heat affected zone (HAZ) of the welded Al-alloys is prone to fail due to coarse microstructure and poor mechanical properties. Therefore, any improvement in HAZ may extend the service life of the welded component. The hypothesis of this study is that localized application of friction stir processing (FSP) before welding may improve the mechanical properties of HAZ, and thus, may reduce the fatigue crack growth rate. The 5083 Al-alloy plates were joined by following two different routes: application of gas metal arc welding in a conventional way, and application of gas metal arc welding after FSP of the bevel zones of the plates which are going to be affected by heat input. To investigate the improvements, hardness, tensile and fatigue crack propagation tests were performed, and microstructures and fracture surfaces were investigated by optical and electron microscopy.