Experimental Investigation on Mechanical Degradation of Q235B Steel Under the Coupling Action of Axial Tension and Local Cyclic Corrosion

This study aimed to elucidate the degradation mechanism of the mechanical properties of Q235B steel under the coupling action of axial tension and local cyclic corrosion. A custom stress corrosion testing apparatus was designed and fabricated for this purpose. Accelerated tests were conducted with varying corrosion durations (1, 3, and 5.5 days) and stress ratios (0.4, 0.6, and 0.8). The corroded steel plates underwent three-dimensional scanning and static ultimate tensile testing. The study revealed that steel plates with a corrosion rate exceeding 30% displayed characteristic necking, and their cross-sectional integrity was significantly diminished. There was a significant positive correlation between the corrosion rate of steel plates and stress ratios, and the mean cross-sectional loss rate in the corroded areas corresponded to the level of stress corrosion. Additionally, the decline in the nominal mechanical properties parameters (f_yⁿ, f_uⁿ) of the corroded steel plates was directly proportional to their corrosion rate. Two models predicting the corrosion-induced degradation of steel’s mechanical properties, incorporating stress ratio variables, were developed using multivariate linear regression analysis.