Comparative Corrosion Behaviour of Mild Steel and Stainless Steel in Hydrochloric and Nitric Acid Environments: Implications for Sustainable Material Use

Corrosion Behaviour: Mild Steel and Stainless Steel

Abstract

Corrosion of structural metals in acidic environments remains a critical concern for both industrial efficiency and environmental sustainability. This study comparatively investigates the corrosion behaviour of mild steel and stainless steel in hydrochloric acid (HCl) and nitric acid (HNO₃) media at varying concentrations and immersion periods. Weight loss measurements were used to evaluate corrosion rates, supported by comparative analysis over a five-day exposure. The results revealed that corrosion rates increased with acid concentration and exposure time where HNO₃ showing stronger corrosive aggressiveness than HCl due to its oxidizing properties. Mild steel experienced significantly higher mass loss than stainless steel due to the absence of a stable passive oxide layer. A gradual reduction in corrosion rate after prolonged exposure indicated the formation of protective corrosion products that limit further dissolution. Overall, stainless steel demonstrated superior corrosion resistance under all conditions. These findings are vital for material selection in chemical and process industries, particularly where equipment is exposed to acidic effluents. Minimizing corrosion-related failures not only extends the service life of metallic components but also reduces environmental contamination and conserves metallic bioresources through more sustainable industrial practices.