论文部分内容阅读
通过金相显微镜、扫描电镜对厚规格X70管线钢焊接接头进行中性盐雾试验(NSS试验)腐蚀产物形貌进行观察,采用EDS、XRD分别对腐蚀产物进行面扫描和物相分析。结果表明,盐雾腐蚀过程先发生点蚀,点蚀逐步发展成全面腐蚀。Cl-引起点蚀,点蚀导致裂纹的产生。腐蚀产物成分均匀,主要由铁的氧化物、氯化物和氢氧化物组成。腐蚀速率随着腐蚀时间的延长变缓慢,腐蚀过程中Cl-易穿过外层疏松的腐蚀产物与基体发生反应,而最内层致密的腐蚀产物膜对腐蚀介质的进一步扩散起到阻挡作用,减缓了反应速率提高了耐蚀性。
The morphology of the corrosion product was observed by metallographical microscope and scanning electron microscope. The corrosion products were observed by the neutral salt spray test (NSS test). The surface and phase analysis of the corrosion products were carried out by EDS and XRD respectively. The results show that pitting corrosion occurs first in salt spray and pitting corrosion develops gradually to complete corrosion. Cl- causes pitting and pitting causes cracks. The corrosion products are uniform in composition and consist mainly of iron oxides, chlorides and hydroxides. The corrosion rate becomes slower with the extension of the etching time. During the corrosion process, the corrosion product of Cl- easily reacts with the matrix and the dense innermost layer of the corrosion product film blocks the further diffusion of the corrosion medium. Slow down the reaction rate and improve the corrosion resistance.