X70钢在模拟土壤溶液中点蚀敏感性影响因素交互作用研究

Relative Function of Influence Factors on Pitting Sensitivity of X70 Steel in a Simulated Soil Solution

通过正交试验法,采用动电位扫描技术研究了Cl-浓度、pH值和温度对X70钢在HCO3-＋Cl-介质中电化学行为的交互影响.结果表明：Cl-浓度、pH值、温度三因素对X70管线钢在模拟土壤溶液中腐蚀及钝化行为影响较大,三因素对其点蚀敏感性影响依次为：pH值〉Cl-浓度〉温度;在Cl-浓度为0.010 mol/L、温度35℃、pH值为8.2的模拟土壤溶液中X70钢的点蚀敏感性最大,钝化区间较窄（-0.257~0.204 V）,当电位超过0.204 V时已处于过钝化状态.

The orthogonal statistical analysis in three levels for three influence factors on pitting sensitivity of X70 steel in a simulated siol solution were conducted by means of measurement of polarization curves;The pitting sensitivity of X70 pipeline steel was discussed in terms of variation of pitting potentials.The experimential results showed that the influence of the three factors exhibits the following order：pH value has the gratest impact,then the Cl-concentration,and the temperature has the smallest impact;X70 pipeline steel has the greatest pitting sensitivity when the Cl-concentration is 0.015 mol/L,the temperature is 35℃ and the pH value is 8.2,and Passivation of X70 pipeline steel has a narrow range,which is between-0.52～0.32 V.When the potential is higher than 0.32 V,X70 pipeline steel has been in the state of passivation.