STUDIES ON THE CORROSION BEHAVIOUR OF DUCTILE CAST IRON IN SOME AQUEOUS SOLUTIONS

Abstract

Studies of the corrosion behaviour of metals and alloys are very important fields for scientific and industrial work. The present work includes detailed studies on the corrosion behaviour of ductile cast iron in some aqueous solutions. Cast iron is widely used to make cast components of machinery such as cylinder block, pistons, rings and many other components which are not subjected to high mechanical loads specially dynamic loads. The present work is divided into two main parts: the first part includes the effect of heat treatment on the microstructure, hardness and tensile strength of the as received cast iron. The second part includes the effect of heat treatment and other variables on the corrosion behaviour of as received cast iron in aqueous solutions. This part is divided into four sections. A. Corrosion behaviour of cast iron in H2S04 solutions The effect of heat treatment on corrosion behaviour of cast iron in H2S04 solutions was investigated potentiodynamically under different conditions .of acid concentration, scan rate, temperature, and cyclic voltammetry. It is found that the anodic polarization curves exhibit an active to passive transition. In the active region, the anodic dissolution current density increases with the applied potential. The active region is characterized by a narrow limiting region accompanied by current oscillation prior to the passivation region.