Effect of heat treatment on microstructural and mechanical properties of molybdenum based pm ferrous alloys

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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: RAMONA DAVOUDNEZHAD

Danışman: BİLGEHAN ÖGEL

Özet:

In this study, the effect of different heat treatment processes on microstructural and mechanical properties of Distaloy-DH and Astaloy Mo (Fe-2Cu-1.5Mo) powders are investigated. Powder samples are sintered at 1120°C for 45 minutes in a sintering furnace under reducing atmosphere of: 10% H2 + 90% N2. After sintering, secondary heat treatments are performed on samples. Microstructural characterization of samples is done with optical and electron microscopy. Selective etching is utilized for determining the amount of bainite and martensite in samples. The Distaloy-DH samples yield approximately 1.9% less porosity than Astaloy Mo samples. In all specimens, pearlite, bainite and/or mixture of martensite and bainite phases are obtained based on the isothermal holding temperature or cooling rate from the austenite region. The study revealed that the specimens with martensitic and lower bainitic microstructure yield high TRS values with respect to either pearlitic or upper bainitic microstructures. Moreover, the lower bainitic structures yield similar or higher TRS values with respect to martensitic structures even at lower hardness values.