2205双相不锈钢在不同Cl^-含量的饱和H_2S/CO_2溶液中的腐蚀行为

Corrosion behavior of 2205 duplex stainless steel in saturated H_2S/CO_2 solution containing different Cl-concentration

采用全面腐蚀实验及SEM,EDS等表面分析技术研究了2205双相不锈钢在不同Cl-含量的饱和H2S/CO2溶液中腐蚀速率、腐蚀形态以及腐蚀表面膜层成分,并建立腐蚀过程机制模型。结果表明:随着温度与Cl-浓度的变化,腐蚀速率发生变化的转折点在Cl-浓度为(57-100)×10-6时,p H=4时,Cl-为170×10-6,温度50℃时的腐蚀速率最大,p H=6时,Cl-为170×10-6,温度80℃时的腐蚀速率最大,其最大腐蚀速率不超过0.004 mm/a;腐蚀表面形成较为致密的钝化膜,随着温度与氯离子浓度的升高,表面出现3~5μm的不稳定点蚀核。

The corrosion rate, corrosion morphology and corrosion products of 2205 duplex stainless steel in saturated H2S/CO2 solution containing different Cl-concentration were investigated. The morphology and characteristics of corrosion scale on the steel surface were analyzed by SEM and EDS. The corrosion process model was set up on the basis of analyzing the corrosion process and composition of corrosion film for the duplex stainless steel. The results show that the corrosion rate changes with the increasing temperature and C1- concentration, and the turning point of corrosion rate occurs when the Cl-concentration is in the range of （57 -100） × 10-6. The corrosion rate reaches the maximum value when Cl-concentration is 170 × 10-6 and temperature is 50 ℃ for the solution with pH of 4. The maximum corrosion rate is observed when Cl-eoncentration is 170 × 10 6 and temperature is 80 ℃ for the solution with pH of 6. The maximum value of corrosion rate is lower than 0. 004 mm/a. A relatively dense passivating film forms on the surface of 2205 duplex stainless steel by general corrosion. The unstable pitting nuclei with a diameter of 3-5 μm form on the surface of the steel with the increasing temperature and Cl-concentration.