Influence of organic corrosion inhibitors on pickling corrosion behaviour of sinter-forged C45 steel and 2% Cu alloyed C45 steel

Abstract

Good mechanical and metallurgical properties of powder metallurgy (P/M) materials made them to have limitless applications. In order to minimize corrosion rate during pickling or acid cleaning process corrosion inhibitors are used. In this research work, an attempt is made to investigate the influence of some organic inhibitors with various concentrations on acid pickling corrosion behaviour of sintered & densified C45 steel and 2% Copper addition to C45 steel with both sintered & densified conditions. Organic corrosion inhibitors Thiourea, Glycine and Sodium Benzoate were used. The specimens were subjected to acid pickling with and without organic corrosion inhibitors for 25 hours with 250 ml of 18% hydrochloric acid (HCl) as pickling medium. The weights of the specimen before and after immersion were measured using shimadzu electronic digital weighing balance. The corrosion tests were performed according to the standards. The corrosion behaviour have been analyzed with increase in pH values due to increase in concentrations of inhibitors in the acid solution. The test results were related with the SEM/optical morphology of the corroded surfaces. The corrosion resistance of the C45 steel is increased with the addition of copper. Among the inhibitors taken for investigation, Thiourea reduces the corrosion rate to maximum extent for all the compositions because of the presence of sulphides and nitrides.