The Electrochemical Synthesis of Ferritic Stainless Steel Alloyed With Nb in H2SO4 Environment

Abstract

The current paper, the corrosion behaviors of three types stainless steel alloys with particular Nb element rates synthesized to determine the influence of Nb amount. Niobium is stabilizing element for steels. Besides niobium has higher affinity than chromium. So niobium prevents chromium depletion by making niobium carbide. Niobium microalloying is helpful procedure in order to control recrystallization of steel. Niobium microalloying is related on grain refinement. FSS samples were unalloyed and alloyed with 0.5 and 1% Nb samples. Unalloyed sample is referance sample. The specimens are casting and then forging products. Different heat treatments were applied to samples because of homogenization. The samples were exposed the sulphric acid solution. Ferritic stainless steel (FSS) electrodes were analyzed using electrochemical impedance spectroscopy (EIS). The experiments were performed using with three electrodes system at room temperature. The corrosion product morpholgy on the surface tests of specimens was investigated with SEM. SEM micrographs showed that the samples exposed the generalized pitting in the solution. Corrosion rate was accounted by Stearn-Geary equation. It was observed that both niobium alloying and heat treatment for 30 minutes is increased oxidation resistance of ferritic stainless steel to pitting corrosion. The results indicated that niobium reinforced the passif layer.