温度、HCO_3^-和pH值对X70钢在成都土壤模拟溶液中腐蚀行为的影响

Effects of Temperature,HCO_3^- and pH Value on Corrosion Behavior of X70 Steel in Chengdu Simulated Soil Solution

为了探究高强度管线钢在不同环境因素下的腐蚀行为,采用极化曲线和电化学阻抗技术,结合腐蚀形貌观察研究了X70钢在成都土壤模拟溶液中的电化学腐蚀行为。结果表明:温度、HCO_3^-和pH值都对X70管线钢在成都土壤模拟溶液中的腐蚀电流密度影响较大;在30~80℃过程中,随着温度增加,X70钢腐蚀电流密度呈现先增大后减小的趋势,在温度达到70℃时,极化电阻RP出现临界值,此时X70钢腐蚀速率达到最大值。在不同质量分数HCO_3^-的成都土壤模拟溶液中,X70钢的极化曲线表现为典型的活化溶解特征,随着HCO_3^-质量分数的增大,腐蚀速率规律不明显,呈现先增大后减小再增大再减小的趋势,且在HCO_3^-质量分数为1.0%时,腐蚀现象最严重。在不同pH值条件下,腐蚀速率随着pH值的增大呈现逐渐降低的趋势,腐蚀现象逐渐减弱。

In order to explore the effects of different environmental factors on the corrosion behaviors of high strength steels, the corrosion be- haviors of X70 pipeline steel in simulated solution of Chengdu soil were investigated by potentiodynamic polarization, electrochemical imped- ance spectroscopy （EIS） and scanning electron microscopy （SEM）. Results showed that the corrosion current density of X70 steel was influ- enced significantly by temperature, HCO-3 concentration and pH value in Chengdu soil simulated solution. The corrosion rate of X70 steel was increased and then decreased with the increase of temperature. When the temperature was 70 ℃, there was a critical value of polarization re- sistance, and the corrosion of X70 steel was the most serious at this temperature. Moreover, the polarization curves of X70 pipeline steel had typical characteristics of active dissolution in Chengdu soil simulated solutions with different HCO-3 mass fractions. With the increase of HCO-3 mass fraction, the corrosion rate of X70 steel changed irregularly. When the HCO-3 mass fraction was 1.0%, the corrosion of X70 steel was the most serious. In addition, the corrosion rate of X70 steel was decreased with the increase of pH value.