Experimental and Theoretical Analysis for Hypoeutectic Cast Iron Oxidation Behaviors

Abstract

The anodic dissolution of hypoeutectic cast iron consisting of pearlite and ledeburite was studied in a sulfuric acid solution by electrochemical methods. The oxidation activities of ferrite and cementite, which are two phases in cast iron, are evaluated by their structural and electronic properties according to the first-principles calculations. The results show that the anodic dissolution of ferrite occurs at the more negative potential compared with cementite. With comparison of ledeburite, the microstructure of pearlite is more easily crumbled during anodic dissolution because more of the ferrite dissolves from the framework of pearlite. The first principle calculations demonstrate that the Fe 3d-band center of iron is closer to Fermi level than that of cementite, indicating that Fe atoms in ferrite are more active and prone to suffering electrophilic attack. This is the intrinsic reason that cementite is more stable than ferrite under anodic polarization in the sulfuric acid solution.