THE EFFECT OF MOLYBDENUM ON THE MICROSTRUCTURE OF NODULAR IRON

Abstract

This paper is aimed at studying the effect of molybdenum on the microstructure and mechanical properties of nodular iron, especially under casting conditions. In this investigation, five nodular irons were separately manufactured in an induction furnace using different amounts of molybdenum in ladder-type molds. The number of nodules per square millimeter and the percent of nodularity were not significantly affected by this variation in molybdenum content. In the matrix, the nodules and the ferrite phase were analyzed using a scanning electron microscope, which is able to detect only the molybdenum in the matrix. The mechanical properties, such as hardness, micro-hardness, tensile strength, and yield strength limit, showed an increase with the increasing content of molybdenum. Likewise, the ferrite and perlite phases presented a variation in percentage with the increasing content of the alloying element. This in turn had a very marked effect on the inter-lamellar spacing of the pearlite. Based on the results of the study, it was concluded that in these quantities, Moferrite solid solution precipitates during solidification, which improves the mechanical properties of the material.