METALLURGICAL, MECHANICAL AND ELECTROCHEMICAL BEHAVIOR STUDY OF THE LAMELLAR GRAY CAST IRON TREATED WITH NIOBIUM

摘要

This study relates to the material science field research and development, opening for industrial applications especially in the development area of materials by molding. The purpose of this study was to determine the influence of niobium on micrographic, mechanical and electrochemical properties of gray cast iron with lamellar graphite EN-FGL250. We investigated the effect of the addition, during the casting of the metal in the mold, such as niobium in powder form and a particle size of 0.5 mm and at a weight ratio of 1%, 3% and 5% on structural and mechanical properties of gray cast iron with lamellar graphite EN-FGL250. The source of these additions being ferroalloys; the originality of this work is that the addition will be made in the last step of cooling the melt cast iron, compared to what is traditionally done (the addition of the element in the melt). These additions will have a significant impact on the phenomenon of solidification as the metal powder deposited in the sand molds creates new centers of germination and absorbs a lot of heat so it cools faster. As result of this study we can say that the cooling rate directly affects the structural, mechanical and electrochemical behavior; this is confirmed by the different techniques used. Namely, a slight decrease in the elasticity of the test pieces, with a reduction of the maximum resistance Rm, the addition of niobium has the effect of reducing considerably the corrosion current.