温度对718镍基合金在高酸性环境下耐腐蚀性能的影响

718镍基合金是高酸性油气井中常用的金属材料,但目前对其腐蚀机理和影响因素的研究较少。利用高温高压反应釜进行腐蚀模拟,采用失重法、扫描电镜(SEM)等手段研究了温度对718镍基合金在高含H_2S/CO_2环境下腐蚀行为的影响。结果表明:在CO_2分压3.5 MPa、H_2S分压3.5 MPa、Cl~-含量150 000 mg/L的模拟环境下,718镍基合金在150,175,205℃下均呈现全面腐蚀,未出现点蚀和局部腐蚀。但随温度升高,镍基合金718的均匀腐蚀速率逐渐增加,材料表面钝化膜出现硫化,并逐渐向腐蚀产物膜转变,质地由致密变得疏松。

Effect of Temperature on Corrosion Behavior of Inconel 718 Alloy in Highly Acidic Environment

Nickel-based alloy 718 is a kind of metal materials which is used commonly in high acidic oil and gas wells.However,the corrosion mechanism and influencing factors are researched less.In this work,high temperature and high pressure corrosion environments were stimulated,and the effect of temperature on corrosion of Inconel 718 alloy was discussed by SEM and weight loss methods.Result showed that on the surface of Inconel 718 alloy,the general corrosion occurred and the pitting and local corrosion did not happen at 150,175,205 ℃ in high acidic environment of 3.5 MPa CO2,3.5 MPa H2S partial pressure,150 000 mg/L C1-content.However,the corrosion rate was gradually increased with the increase of temperature.Surface passivation film began to vulcanize and gradually transformed into the corrosion product film.Besides,the dense texture became loose.