Study of the Corrosion Behavior of 304 Stainless Steel in HCl‐Based Etching Systems

ABSTRACT 304 stainless steel is often subjected to corrosion challenges from HCl and HCl‐H 2 O 2 . This study utilized electrochemical and surface characterization methods to investigate the corrosion process, mechanisms, and products of 304 stainless steel in both HCl and HCl‐H 2 O 2 solutions. In HCl solution, corrosion initiated from the penetration and destruction of the passivation film by Cl ‐ and the H + reduction reaction. As the concentration of HCl increased, the corrosion transitioned from pitting corrosion to intergranular corrosion, with chlorides identified as the corrosion products. In HCl‐H 2 O 2 solution, Fe 2+ reacted with H 2 O 2 via the Fenton reaction to generate ·OH, which facilitated the progression of both pitting and intergranular corrosion. Fe 3+ catalyzed the decomposition of H 2 O 2 , resulting in increased oxygen content and accelerated corrosion rates. At lower concentrations of H 2 O 2 , the corrosion products were primarily chlorides; at concentrations of 3 M or higher, the products shifted to basic chlorides.