Determination of Phase Equilibria in High Alloy White Cast Irons
AbstractWhite cast irons are hypoeutectic alloys in which the carbon remains dissolved in the iron carbide phase, called cementite, without decomposing into graphite during solidification. Because of the hard cementite phase, they preferred in high abrasion resistance required applications. In order to improve further the wear resistance they are alloyed with strong carbide forming elements (W, Mn, Mo, S, Cr, V, Mg, etc.). There is a strong relationship between the mechanical properties of alloys and the internal structure they possess. In order to reveal the effect of the internal structure, the diagrams showing the phase equilibria of the material should be known. Today, various software programs are used to make thermodynamic calculations relevant to phase equilibria. In this study, using the Materials Calculator software program, it is aimed to simulate the pseudo binary phase diagrams (i.e. isoplethal maps) where the molar fractions of alloying elements other than carbon are fixed. In order to check the accuracy of the constructed diagrams, the casted samples with determined compositions will be analyzed by differential scanning calorimetry (DSC) and the theoretical and experimental data will be compared. The diagrams for changing the type and amount of the alloying addition will be examined and the effects of changing the amount and distribution of carbides with increasing carbon content and temperature will be discussed to improve the wear resistance.