Effect of Temperature and Concentration on the Corrosion Behavior of 42CrMoE Low Alloy Steel in Boric Acid Solution

This study investigated the corrosion behavior and mechanism of 42CrMoE LAS in boric acid solutions with varying concentrations (2500-37000 mg/l) and temperatures (25-97.5 °C) using electrochemical measurement and weight loss immersion experiment. Results revealed that at a low boric acid concentration, the corrosion rate initially increased and subsequently decreased with increasing temperature. While at higher concentrations, the corrosion rate exhibited a monotonic increase with increasing temperature. Additionally, the steel displayed pitting corrosion, which intensified with increasing boric acid concentrations. However, at high temperature, pits corrosion transformed toward uniform corrosion. The interrelated effects of temperature and boric acid concentration primarily modulated the pH and dissolved oxygen content, consequently impacting the corrosion behavior. With escalating temperature and concentration, corrosion products transformed from protective Fe₂O₃ and Fe₃O₄ to inadequately protective FeOOH, ultimately resulting in an increased corrosion rate of 42CrMoE LAS.