储罐用12MnNiVR钢在海水中的腐蚀行为

Corrosion Behavior of 12MnNiVR Steel in Seawater Environment

以日照油库工程为背景,研究国产12MnNiVR钢在海水中的腐蚀行为。采用静态浸泡方法测定钢在海水的腐蚀速率,并研究施加牺牲阳极对钢的保护效果。采用扫描电镜和X衍射方法检查腐蚀形貌及鉴定腐蚀产物的组成。结果表明:罐底部的腐蚀速率要大于其顶部的腐蚀速率、施加阴极保护试片的腐蚀速率明显小于未加阴极保护者;采用合理的牺牲阳极保护后,罐底、罐顶及管壁处只会发生轻微的均匀腐蚀,腐蚀产物致密,无明显的腐蚀坑,腐蚀程度在设计允许的范围内;未加阴极保护的金属表面腐蚀程度不均匀,腐蚀产物疏松多孔,呈现局部腐蚀特征。

There are many large oil tanks constructed in coastal area for its good natural conditions. During hydraulic inspection of which, seawater is often employed for saving cost. The paper investigated the corrosion performance of 12MnNiVR steel in seawaters aiming to simulate the corrosion occurred on the bottom, wall and roof of the oil tank. A comparison study was performed to investigate the effectiveness of sacrificial anode for the steel. The corrosion morphology and products were examined by SEM and XRD techniques. The results show that corrosion rate of the tank bottom is greater than that of the tank roof. The corrosion rate of 12MnNiVR steel decreases obviously when the protection with sacrificial anode is applied to the test specimens, i.e. only a slight uniform corrosion occurs for the specimens on the bottom, roof and wall of the tank; the corrosion product is compact and there is no obvious corrosion pits on the surface; in that case the corrosion degree is within the allowable range of the design specification. In the case of no cathodic protection, the metal surface becocmes rough with porous corrosion product, presenting the feature of local corrosion.