Experimental study of corrosion behavior between the material-type and process-type super-high sucker rod steels in a near neutral high sulfide environment

Corrosion behavior of material-type (HL) and process-type (HY) super-strength sucker rod steels 11Mn2SiCrMoA (BZ-11H) and 30CrMoA in a high sulfide-containing solution is investigated by electrochemical measurement, weight loss method, electron probe micro analysis (EPMA), energy dispersive X-ray (EDX) and X-ray diffraction (BZ-11H) analysis, respectively. The results show that BZ-11H steel has a higher corrosion resistance than 30CrMoA in the near neutral high sulfide environment. EDX and XRD analysis results indicate that the corrosion processes of these two materials are mainly controlled by the small amount of alloy elements they contain, which also determine the contents of corrosion product deposits and the difference in corrosion rates . The interactions between Fe, SO 4 2− , CO 2 and O 2 lead to the formation of FeS, FeCO 3 and Fe 2 O 3 , and consequently cause the difference in corrosion rate or corrosion resistance .