温度对不同含水率土壤中碳钢腐蚀行为的影响

Effects of Temperature and Water Content on Corrosion of Carbon Steel in Soil

中原油田气举管网的土壤腐蚀十分严重。为此,采用极化曲线测试技术和电化学阻抗谱,研究了20碳钢在25,55,85℃的正常含水率(21%WHC)和高含水率(45%WHC)的中原油田土壤(较高盐含量)中的腐蚀行为。结果表明,在同一温度下,正常含水率的土壤中碳钢腐蚀速率均大于高含水率土壤时的腐蚀速率。温度对碳钢腐蚀的作用与土壤含水率有关,85℃时在正常含水率的土壤中碳钢的自腐蚀电流增大到68.42μA/cm2,而此时在高含水率的土壤中碳钢自腐蚀电流变化较小(13.06μA/cm2),这与阻抗结果相符。正常含水率的土壤中温度对土壤腐蚀的影响大于对高含水率时的影响。

With a view to the serious corrosion of the gas-conveyance pipelines buried in soils of Zhongyuan oil field, the corrosion behavior of AISI -1020 carbon steel in the soils with water contents of 21% and 45% at temperatures of 25℃, 55℃, and 85℃ was studied by means of polarization curve technique and electrochemical impedance spectroscopy (EIS). It was found that the corrosion rate of the carbon steels in the soils with a water content of 21 % was larger than that in the soils with a water content of 45%. Moreover, the effect of temperature on the corrosion of the carbon steel depended on water content in soils. Namely, the corrosion current of the carbon steel in the soils with a water content of 21% and at 85℃ increased to 68.42 μA/cm2, but it had little change (13.06μA/cm2) in the soils with a water content of 45%, which well conformed with the results obtained by FJS. In general, the carbon steel was more sensitive to temperature in the soils with normal water content of 21 % than in the soils with a high water content of 45% in terms of the corrosion.