Early corrosion stage of welded carbon steel joints in CO2-saturated oilfield water

Abstract The early corrosion stage of carbon steel welded joints in water occurring in a CO 2 -saturated oilfield was investigated. Electron backscatter diffraction (EBSD) and energy dispersive X-ray spectrometry (EDS) were used to characterize the microstructure and chemical composition distribution of the different zones in the welded joint. Atomic force microscopy (AFM) and a VEECO optical profiler were used to observe the sample surface corrosion morphology at different immersion times. The results show that the early stage corrosion characteristics of each zone in the welded joint are related to grain orientation and not related to grain size, grain boundary type, or to the second phase. Additionally, it was found that chemical composition distribution is the primary reason for the differences in the early stage corrosion characteristics observed for each zone in the welded joints.