Fe基高Cr激光熔覆涂层CO2腐蚀行为研究

采用电化学工作站测试了激光熔覆Fe-20Cr、Fe-30Cr、Fe-40Cr涂层在含CO2饱和地层水中的腐蚀行为,研究了温度和Cl-浓度对其腐蚀的影响规律,并与P110套管钢进行了对比。通过对涂层进行X射线衍射(XRD)分析,解释了涂层Cr含量不同时耐蚀性的差异。结果表明:随温度升高,涂层钝化区间变窄,耐蚀性随温度升高而降低;当温度为85℃时,涂层具有比P110钢更低的腐蚀倾向和更优异的抗点蚀性;Cl-浓度与耐蚀性存在一临界值,当Cl-浓度达1 mol/L时,腐蚀性最强。低Cr含量的Fe-20Cr涂层具有较高的耐蚀性,随着Cr含量的增加,Cr23C6、Cr7C3等碳化物在晶界处析出,产生晶体贫铬区,进而降低了高Cr含量涂层的耐蚀性。

Carbon dioxide corrosion behavior of Fe-based high chromium laser cladding coating

The electrochemical corrosion behavior of laser cladding Fe-20Cr,Fe-30Cr and Fe-40Cr coatings and P110 steel was tested in simulated saturation formation water under the condition of injection of CO2.The effects of temperature and concentration of Cl-were also studied.The corrosion mechanism was developed on the basis of phase analysis results of X ray diffraction(XRD).The results show that the passivation region decreases with temperature,which reflects the decreasing of corrosion resistance.There exists a critical value of concentration of Cl-(1 mol/L) and corrosion resistance.At the temperature of 85 ℃,the coating shows the excellent pitting corrosion resistance and lower corrosion tendency.The corrosion resistance of low Cr content of Fe-20Cr coating is higher,Cr7C3 and Cr23C6 are formed in grain boundary.These excess carbides are generated around the chromium depleted zone,resulting in corrosion resistance greatly reduces.