The dual nature of Cu content on the corrosion resistance of low alloy steels in sulfuric acid: A time-dependent reversal of corrosion resistance

The corrosion performance of low alloy steels with varying Cu contents (ranging from 0 to 1.2 wt.%) was evaluated in a 10 wt.% H2SO4 solution at room temperature. By incorporating Cu, the active dissolution of the bare steel is effectively suppressed, leading to enhance corrosion resistance as the Cu content increases. However, during immersion, the corrosion product film transitions from CuO and Cu(OH)2 dominance to Cu2O dominance. Simultaneously, hydrogen reduction induces cracks in the film, causing an uneven Cu distribution and gradual corrosion resistance degradation with higher Cu content and longer immersion duration.