Investigation of the microstructural and mechanical properties ofDP500 and DP700 quality steels welded with different heat inputs


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Tezin Türü: Yüksek Lisans

Tezin Yürütüldüğü Kurum: Orta Doğu Teknik Üniversitesi, Fen Bilimleri Enstitüsü, Fen Bilimleri Enstitüsü, Türkiye

Tezin Onay Tarihi: 2023

Tezin Dili: İngilizce

Öğrenci: KARDELEN YILMAZ

Asıl Danışman (Eş Danışmanlı Tezler İçin): Bilgehan Ögel

Eş Danışman: Caner Batıgün

Özet:

783973 NOLU TEZ

The purpose of this study is to compare the different welding heat input effects on microstructural and mechanical properties of Dual Phase (DP) DP500 and DP700 steels. The welding operations were carried out manually by using Tungsten Inert Gas Welding (TIG), MAG (Metal Active Gas) Pulse Arc Welding and MAG Cold Metal Transfer (CMT) arc methods with keeping different heat inputs. The specimens welded under specified conditions were inspected initially by metallographic methods. In addition, destructive tests such as tensile testing and bending testing were also applied. Results obtained indicate that different heat input and cooling rate conditions cause formation of different phase distributions especially in the Heat Affected Zone (HAZ). The study concludes that Heat Affected Zone (HAZ) 3 region is the weakest location of welded specimens due to martensite tempering. Bainite formation gives the best results in elongation and strength for welding methods of CMT method under Medium Heat Input (MHI) conditions. MAG Pulse Method under Medium Heat Input circumstances is perfect for ductility consideration of DP500 and DP700. Heat input causes hardness changes across the welded specimens.