含水率对X70钢在滨海土壤中腐蚀行为的影响

X70钢作为新型管线钢，目前正大量地应用于输气管道的建设。对X70钢的土壤腐蚀问题进行了实验研究，采用极化曲线、交流阻抗技术对相对含水率在38％-100％（WHC）的青岛滨海土壤中的腐蚀行为进行研究，分析了含水率对土壤腐蚀的影响。结果表明：X70钢在不同含水率土壤中的腐蚀受阴极极化控制。土壤的密实程度和可溶性盐的离子化程度导致不同含水率的土壤腐蚀规律如下：中高含水率对腐蚀速率影响显著，相对含水率小于等于45％时腐蚀速率较小且变化不明显，高于45％时腐蚀速率呈现先迅速升高后降低的趋势，在65％时达到最大；高含水率的土壤中有中间腐蚀产物膜形成。

Influences of Water Content on the Corrosion Behavior of X70 Steel in Coastal Soil

X70 steel is applied to the construction of gas pipeline massively as a new pipeline steel.Soil corrosion of X70 steel is investigated in this paper.The corrosion behavior of X70 steel in coastal soil with 38%~100% water holding capacity(WHC)is studied by polarization curve measurement and electrochemical impedance spectroscopy.The effect of WHC of soil corrosion is analyzed in detailed.The results of experiments show that X70 steel corrosion in soil of different humidities can be controlled by cathodic polarization.The compaction degree of soil and the soluble salt ionization degree lead to soil corrosion with different content of water.A high humidity has a significant effect on soil corrosion.When the WHC is less than or equal to 45%,the corrosion rate is low and changes slightly.But when it is higher than 45%,firstly the corrosion rate increases sharply,then reduces and reaches the maximum point when the water content is 65%.In a high humidity,there are middle corrosion products membrane formed on anticathodic surfaces.