交流干扰下不同组织X80钢在碱性土壤环境中的腐蚀行为

Corrosion behavior of X80 pipeline steel with different microstructure under AC interference in alkaline soil environment

采用极化曲线、Mott-Schottky曲线和浸泡腐蚀实验研究了交流干扰下不同组织X80钢在CO_3^(2-)/HCO_3^-溶液中的腐蚀行为,并探讨了交流电和温度的协同作用。结果表明:随交流电流密度的增加,不同组织钢的钝性下降,维钝电流密度增加,临界点蚀电位负移,钝化膜内的点缺陷数量增加;交流干扰可阻碍钝化膜的形成,降低膜的稳定性,增加膜破裂的可能性,减薄膜的厚度;交流电的作用对不同组织钢的钝化膜的破坏是不同的,正火组织钢钝化膜的稳定性最好;交流干扰下不同组织钢的腐蚀形态均为局部腐蚀,正火组织钢的耐蚀性最好,其次为热轧组织,退火组织的耐蚀性最差。X80钢的交流腐蚀行为与其组织结构密切相关,交流干扰和温度的升高可产生协同作用,明显降低钝化膜的稳定性,加剧腐蚀的发生。

The corrosion behavior of X80 pipeline steel with different microstructure under AC interference in CO32-/HCO3- solution was investigated by means of polarization curves, Mott-Schottky curve and immersion corrosion test, and the synergistic effect of AC interference and temperature was also analyzed. The results show that with the increase of AC current density, the passivity of the X80 steel with different microstructure reduces, the passive current density increases, the critical pitting potential shifts negatively and the amount of point defects in the passive film increases. The AC interference can inhibit the formation of passive film, reduce the stability of the film, enhance the breakdown possibility of the film and decrease the film thickness. The effect of AC on the damage of passive film of the steel with different microstructure is different, compared with other microstructure, the stability of the passive film formed on the steel with normalized microstructure under AC interference is the best. The corrosion morphology of the steel with different microstructure under AC interference is local corrosion, and the corrosion resistance of the steel with normalized microstructure is the best, followed by hot-rolled microstructure, and the corrosion resistance of annealed microstructure is the worst. The AC corrosion behavior of the X80 steel in the solution is closely related to its microstructure, and the AC interference and the increase of temperature can produce synergistic effect, which can obviously reduce the stability of passive film and aggravate the occurrence of corrosion.