Cl~-浓度对双相钢和镍基合金腐蚀速率的影响

针对H2S、CO2、Cl-同时存在的高温、高压腐蚀环境,选择22Cr、25Cr双相不锈钢和028铁-镍基合金、G3镍基合金进行对比试验,在其它条件相同的情况下(H2S/CO2分压、温度、液体流动等条件一致,仅Cl-浓度变化),分析Cl-含量对各种耐蚀合金管材发生均匀腐蚀与点蚀的腐蚀速率的影响。结果表明,在温度为160℃,CO2分压为4.13MPa,H2S分压为2.66MPa,流速为3m/s的条件下,随着Cl-浓度增加(25g/L、100g/L、120g/L、250g/L),UNS S32205和UNS S32750两种双相不锈钢的均匀腐蚀速率和局部腐蚀速率增加;028和G3两种镍基合金的均匀腐蚀速率变化不大,且无局部腐蚀发生。UNS S32205、UNS S32750双相不锈钢试样表面钝化膜的主要成分为Cr2O3和/或Cr(OH)3;028和G3镍基合金试样表面钝化膜的主要成分为NiO、Cr2O3和/或Cr(OH)3。

Influence of Cl~- Concentration on Corrosion Rates of Duples Stainless Steels and Ni-based Alloys

Aimed high temperature high pressure at HTHP corrosive environments with simultaneous existence of H2S/CO2/Cl-,22Cr/25Cr duplex stainless steels,i.e.,(DSS) and 028 Fe-Ni-based alloy/G3 Ni-based alloy were selected to conduct comparative tests.Under the same conditions other than Cl-concentration,i.e.,(H2S/CO2 partial pressure,temperature and liguid flow were the same,only Cl-concentration was different,the influence of Cl-concentration on corrosion rates of general corrosion and pitting corrosion of corrosion resistant alloys was analyzed.The experimenal results show that under the corrosive conditions of temperature 160 ℃,CO2 partial pressure 4.13 MPa,H2S partial pressure 2.66 MPa and flow rate 3 m/s,with the increase of Cl-concentration(25 g/L,100 g/L,120 g/L,250 g/L),the general corrosion rates and localized corrosion rates of two kinds of duplex stainless steels(UNS S32205 and UNS S32750) increased.The general corrosion rates of 028 and G3 Ni-based alloys had a little change and localized corrosion did not happen.The main compostion of passivation film on the surface of DSS specimen(UNS S32205/UNS S32750) was Cr2O3 and/or Cr(OH)3.The main compostion of passivation film on the surface of Ni-based alloy specimen(028/G3) was NiO/Cr2O3 and/or Cr(OH)3.