Effect of corrosion on the fatigue crack propagation properties of butt weld with G20Mn5QT cast steel and Q355D steel in 3.5‐wt% NaCl solution.

The corrosion fatigue crack propagation (FCP) of the butt weld with G20Mn5QT cast steel and Q355D steel in 3.5‐wt% NaCl solution was investigated experimentally. Considering the influences of stress ratio and loading frequency, the corrosion FCP rate curve was obtained. The results indicated that the corrosion FCP rate in the corrosion environment is three times that in air. Increasing the stress ratio or decreasing the loading frequency will increase the corrosion FCP rate. The fracture morphology of the specimens in the corrosion environment had more corrosion pits and intergranular characteristics due to anodic dissolution than that in air. Anodic dissolution and hydrogen embrittlement jointly promoted the corrosion FCP of butt weld in simulated seawater. The corrosion FCP rate model was established considering the effects of stress ratio and loading frequency. Highlights: Corrosion accelerated corrosion fatigue crack propagation (FCP) significantly.The corrosion FCP rate increases with the increase of R and the decrease of f.The mathematical model of corrosion FCP rate of butt weld is proposed. [ABSTRACT FROM AUTHOR]