激光熔覆Fe基高Cr涂层组织及抗CO_2腐蚀性能研究

采用激光熔覆方法制备了Fe-20Cr、Fe-30Cr、Fe-40Cr共3种不同Cr含量的Fe基涂层。用扫描电镜(SEM)和X射线衍射(XRD)分析了涂层的微观组织和物相,借助电化学工作站测试了涂层在含CO2饱和地层水中的腐蚀行为,并与P110套管钢进行了对比。结果表明:激光熔覆Fe基含Cr涂层皆为冶金结合,熔覆层质量良好。在地层水中通入CO2后3种涂层腐蚀趋势变大,但由于表面疏松CaCO3和MgCO3产物的形成,抑制了涂层的腐蚀。低Cr含量的Fe-20Cr涂层具有较高的耐蚀性。Cr含量增加时,由于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,但碳化物析出提高了涂层的硬度。

Study on Fe-based Laser Cladding High Cr Coating Microstructure and Its CO2 Corrosion Resistance

The laser cladding method was employed to prepare Fe-20Cr,Fe-30Cr and Fe-40Cr coatings,and their microstructure and phase were analyzed with the scanning electron microscopy(SEM) and X-ray diffraction(XRD) methods,including the testing of their electrochemical corrosion in formation water and their comparison with P110 casing steel.The results show that three cladding layers are metallurgical combination with good quality.The corrosion velocity can rise while injecting CO2 into formation water,and the CaCO3 and MgCO3 formation can restrain the coating corrosion.The Fe-20Cr coating with low Cr content has high corrosion resistance.With the increase of Cr content,the precipitation of Cr7C3 and Cr23C6 in grain boundary can produce chromium depleted zone and can result in the decrease of corrosion resistance,but these carbides can improve the hardness of cladding layer.