Fracture and fatigue crack growth characterization of conventional and head hardened railway rail steels

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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: 2014

Öğrenci: ALI MOTAMENI TABATABAEI

Danışman: RIZA GÜRBÜZ

Özet:

Fatigue crack growth behaviors of rail R260 and rail R350 HT in head, web and foot region of the rail have been investigated. Crack propagation at these three regions were compared. Furthermore, Fracture toughness (KIC) values in the three region of the rail R260 and R350 HT were calculated. Compact shear specimens were machined from the web of the rail in the longitudinal direction to conduct KIIC fracture toughness of the rail R260. A special loading frame manufactured for KIIC testing. Fractographic analysis on the fracture surfaces of both mode I and mode II fracture toughness test specimens and mode I fatigue crack growth test specimens were done. KIIC values were measured 1.5 times the KIC values for this steel in the web of the rail R260 grade in the longitudinal direction. As for mode I fatigue crack growth rates, head of both the rails in transvers direction shows the highest mode I fatigue crack growth resistance