Summary
Corrosion by aqueous HCl solutions (hydrochloric acid) involves an electrochemical reaction. Water containing the acid and other dissolved ions serves as the electrolyte. Corrosion of carbon steel by an aqueous HCl solution commonly leads to relatively uniform thinning at a rate that is usually acceptable for pH > 5; carbon and low alloy steels are more susceptible but stainless steels by no means immune.