模拟地面集输环境下温度对2205双相钢均匀腐蚀及点蚀行为的影响

Effect of Temperature on Uniform Corrosion and Pitting Behavior of 2205 Duplex Stainless Steel in Simulated Ground Gathering and Transportation Environment

针对油气集输管线在CO2和含高浓度的Cl-地层水环境中易发生腐蚀失效的问题,通过腐蚀失重试验和电化学测试分析,研究了2205双相不锈钢在高分压CO2+高矿化度+高浓度Cl-地层水集输管线环境中的腐蚀行为。结果表明:在模拟油田集输管线环境中,升温引起的2205双相不锈钢的均匀腐蚀速率基本不变,整体表现为轻度腐蚀,但由于Cl-的存在,2205双相钢在50℃和70℃时出现明显的点蚀坑形貌;2205双相钢在3种测试温度下的阳极极化曲线存在明显的钝化区,随着温度的升高,2205双相钢的点蚀电位先升高、再下降,在30~50℃,存在一个临界点蚀温度CPT;交流阻抗图谱在50℃和70℃分别表现出了点蚀诱导期和点蚀发展期的特征。

In view of the problem that oil and gas gathering and transportation pipeline is prone to corrosion failure in CO2 and the high-concentration Cl-formation water environment,the corrosion behavior of 2205 duplex stainless steel in the high-pressure CO2+high-salinity+high-concentration Cl-formation water gathering and transportation pipeline environment was studied through the corrosion weight loss test and the electrochemical test analysis.The results show that the uniform corrosion rate of 2205 duplex stainless steel caused by the temperature rise is basically unchanged,and the overall corrosion showed is mild corrosion.However,due to the presence of Cl-,the 2205 duplex steel shows obvious pitting pit morphology at 50℃and 70℃.The anode polarization curve of 2205 duplex steel showed the obvious passivation zone under three test temperatures.With the increase of the temperature,the pitting potential of 2205 increased firstly,and then decreased,and there was a critical pitting temperature CPT between 30℃and 50℃.At 50℃and 70℃,AC impedance spectrum showed the characteristics of the pitting induction period and the pitting development period respectively.