The influence of copper content on corrosion behavior of ductile iron and austempered ductile iron

oai:repozitorij.simet.unizg.hr:simet_232The effect of copper content on corrosion behavior of ductile iron and austempered ductile iron was investigated in 0.5 mol dm-3 NaCl solution at T = 20°C by open circuit potential measurements, linear and potentiodynamic polarisation methods. Ductile iron specimens used in this paper had: 0.031 wt.% Cu and 0.91 wt.% Cu. Specimens were austenitised at 850°C for 60 min and then austempered at 420°C for 60 min in 50% NaNO3 and 50% KNO3 salt bath. The mechanism of the corrosion attack developed on the material surface was analysed by light microscopy, scanning electron microscopy (SEM) and energy dispersive X-ray analysis (EDX).The results of the electrochemical investigations indicated that corrosion rate generally decrease with the increase in copper content in alloy. Also, higher corrosion resistance showed austempered ductile iron samples compared to ductile iron samples with the same chemical composition