THE ROLE OF CHROMIUM OR COBALT ALLOYING OF PLAIN STEELS (LOW RESIDUAL) ON THEIR CORROSION BEHAVIOR IN HYDROCHLORIC ACIDS

An electrochemical corrosion study is conducted on the effect of chrom ium or cobalt alloying of low residual plain carbon steels on its corr osion resistance in different concentrations of hydrochloric acid solu tions. The study was carried partly due to insufficient experimental d ata available in the literature on the effects of alloying elements on the corrosion resistance of these steels. It is found that alloying c arbon steels with 2% chromium will lead to a lower corrosion rate at h igh acid concentration. A similar behavior is observed when cobalt (e. g. 2 wt.%) is the alloying element. The corrosion reaction of the plai n steels and chromium alloyed are under mixed control. The corrosion r eaction of the cobalt alloyed steels was found to be anodically contro lled at low carbon content and under mixed control at high carbon cont ent. The previously reported anomalous behavior in the corrosion tende ncy in the presence of cobalt or chromium alloying was also observed i n this investigation.