300M超高强度钢在模拟积水环境中的腐蚀行为

 针对飞机结构部件在服役过程中存在的缝隙积水导致结构材料腐蚀的问题,通过研究腐蚀产物、形貌、失重、腐蚀速率、腐蚀损伤度以及积水溶液与暴露金属的面容比、pH值等的变化,探讨了300M超高强度钢在模拟积水环境中的腐蚀行为。结果表明,300M钢在模拟积水中的腐蚀是从点蚀开始,然后点蚀坑扩展合并,逐渐发展为全面腐蚀,其腐蚀失重和腐蚀损伤度随腐蚀时间的增加而增大,腐蚀损伤度则呈现出幂函数变化趋势;随腐蚀时间的延长,模拟积水环境中的pH值从初期的4.2升到5.2再下降到4.8～5.0,平均腐蚀速率也从0.289 g/(m²·h)线性减小到0.120 g/(m²·h);电化学交流阻抗结果表明随腐蚀时间的延长,容抗弧半径逐渐增大,说明腐蚀产物对基体起到一定的保护作用,这与腐蚀速率变化规律一致;另外,不同的面容比(腐蚀介质体积与300M钢暴露面积之比)对腐蚀过程的影响是:随面容比的增加,腐蚀失重与腐蚀速率均增大。

Corrosion Behavior of 300M Ultra-high Strength Steel in Simulated Gap Water Environment

The gap water produced in an airplane's structural parts during its service usually leads to the corrosion of structure materials. In this paper, the corrosion behavior of 300M ultra-high strength steel in simulated gap water is studied by evaluating the corrosion products, their morphology, weight loss, corrosion rate, damage area, pH of the solution, and the ratio of the corrosion media volume to the exposed area of 300M steel, etc. The results show that the corrosion initiates with pitting, and gradually developes into general corrosion with the pits scaling out and merging. As corrosion time extends, both corrosion weight loss and damage area ratio increase, while the corrosion damage area ratio exhibits a trend of power function. The pH in the simulated gap water first increases from 4.2 to 5.2 and then decreases to 4.8-5.0. The average corrosion rate decreases linearly from 0.289 g/(m²·h) to 0.120 g/(m²·h). The results of electrochemical impedance spectroscopy indicate that the size of the capacitive reactance arc increases with the extension of corrosion time. It illustrates that the corrosion products formed in the surface of steel seem to protect the matrix, which agree with the regular pattern of corrosion rate. In addition, the increase in area-to-volume ratio, i.e., the ratio of corrosion media volume to the exposed area of 300M steel, results in an increase in corrosion weight loss and corrosion rate.