Effect of salt corrosion on the fracture toughness of high-performance steels

This study investigated the change in fracture toughness of two high-performance steels, Q420qDNH weathering steel and Q690 high-strength steel, after pre-corrosion treatment in chloride salt environments. The impact toughness of both steels after exposure to corrosion for varying durations was measured using the Charpy pendulum impact test, and the fracture toughness was calculated based on established empirical formulas. The experimental results indicated that steel corrosion initially progressed rapidly, followed by a gradual decrease in the corrosion rate. The impact energy of the specimens decreased with prolonged corrosion time, and when the corrosion reached a certain threshold, the impact energy fell below the specified requirements, suggesting material embrittlement. Both steels exhibited similar trends in impact toughness degradation over time, with the Q690 high-strength steel demonstrating superior fracture toughness after corrosion. In conclusion, long-term exposure to chloride salt environments significantly affected the impact toughness of both Q420qDNH weathering steel and Q690 high-strength steel.