ERİŞİR Ersoy University of Kocaeli

Spoluautoři BILIR Oğuz Gürkan

In this study, the suitability for producing dual phase steel from hot rolled medium carbon steel for mining industry and the effect of annealing temperature on hardness and microstructure has been investigated. The critical equilibrium temperatures and phase diagram were calculated using Thermo-Calc software for %0.37C-%0.87Mn steel. In experimental studies using dilatometer, microstructures containing ferrite and martensite were produced by intermediate quenching method with annealing at different temperatures followed by water quenching. Before the intermediate quenching, the specimens were first quenched to form martensite from austenitizing temperature of 1200 °C. Fully martensitic samples were then annealed respectively at 725, 730, 740, 750 °C for 15 min and quenched. During the annealing, the austenite nucleates and grows at former boundaries of the martensite plates resulting fibrous microstructure of martensite and ferrite. Microstructural investigations were carried out using light microscope and scanning electron microscope to investigate the effect of the increasing annealing temperature on the microstructure. Vickers test was applied to specimens. The calculations and experimental results show that hot rolled medium carbon steels are suitable to produce a dual phase microstructure. It was observed that increasing annealing temperature increases the amount of martensite and hardness because martensite is the main phase controls the hardness value of steel. It is observed that the A1 and A3 temperatures are very close and the percentage of austenite is much more than conventionally produced dual phase steels. It is related to including more carbon content than conventionally produced dual phase steel.

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