The Production of New Structures from Graphitized Hypereutectoid Steel

Abstract
Graphitization process in steels is done during the dissociation of the cementite phase to ferrite and graphite. Since cementite is a metastable phase and graphite is more stable than it, graphitizing transformation occurs during a longer period of time. The presence of alloying elements such as chrome and manganese in common commercial steels results in the necessity of graphitization to be passed at a longer period of time which is not appreciated from the economical viewpoint. However, improving wear resistance and machinability is accounted as one of the main advantages for this process in steels. The final structure obtained after graphitization has been reported mainly as a mixture of ferrite, graphite and a few amounts of cementite. Prolonged annealing time for producing graphitized structure creates a little hardness because of the existence of the ferritic matrix. Therefore matrix has been changed by selecting various heat treatment cycles from ferritic to other types of phases besides new structures that also consist of graphite. Finally their hardness have been measured and compared as a criterion for determining mechanical properties and wear resistance.