Beynitik ve beynitik-martensitik yapılı düşük alaşımlı çeliklerin mekanik davranışları.


Tezin Türü: Yüksek Lisans

Tezin Yürütüldüğü Kurum: Orta Doğu Teknik Üniversitesi, Mühendislik Fakültesi, Metalurji ve Malzeme Mühendisliği Bölümü, Türkiye

Tezin Onay Tarihi: 2019

Öğrenci: Başak Tezgör

Danışman: BİLGEHAN ÖGEL

Özet:

This study aims to investigate the mechanical behavior of bainitic structures and bainitic-martensitic mixed structures in low alloyed steels. In this study, 51CrV4 and 60SiMn5 steels were used with different heat treatment cycles to get bainitic and bainitic-martensitic mixed structures. The specimens were austenitized at 880°C for 51CrV4 and at 950°C for 60SiMn5. It is followed by quenching in salt bath and isothermal holding at various temperatures above and below Ms temperature. Hardness, tensile and charpy impact testing were carried out. Both in 51CrV4 and 60SiMn5 steels, the specimens with bainite-martensite mixed structures show higher UTS values than 100% bainitic ones. The %elongation of 51CrV4 steel specimens were higher than that of 60SiMn5 specimens. The charpy impact toughnesses of 51CrV4 steel specimens varied in the range 12-25 J whereas that of 60SiMn5 speci- mens were below 10 J.