Study on Stress Corrosion Characteristics of Different Grade H Sucker Rods

摘要

In order to obtain the stress corrosion resistance of the different grade H ultra-high-strength sucker rods in high water-bearing fluids and their adaptability to typical well fluids, this paper takes orthogonal stress corrosion test method to research the stress corrosion cracking properties of 30Ni2CrMnMoVA and 30CrMoA under different corrosion conditions including Cl-, HCO3-, Ca2+ and Cl--HCO3- based on the corresponding provisions of NACE TM 0177 and GB/T15970.1. In this paper, the stress corrosion susceptibility of 30Ni2CrMnMoVA and 30CrMoA materials in different corrosion conditions were investigated and the typical working conditions of different grade H sucker rods are clarified that provide the basis for selection and string design of grade H sucker rods. The results showed that the stress corrosion cracking susceptibility of 30Ni2CrMnMoVA and 30CrMoA sucker rods to Cl- and Ca2+ were all β (Cl-)& β (Ca2+). When HCO3- and Ca2+, Cl- coexist, a certain concentration of HCO3– inhibited the stress corrosion of two materials to Cl- and Ca2+. When the concentration of HCO3- is more than 300mg/L, the stress corrosion inhibition of 30Ni2CrMnMoVA to Cl- is obvious and its stress corrosion susceptibility increased but the effect to 30CrMoA is not very obvious with the increase of Cl- concentration. 30Ni2CrMnMoVA sucker rod is not suitable for high Cl- concentration of the well conditions, more suitable for alkaline environment containing HCO3-. However, 30CrMoA is not suitable for the environments with high concentration of HCO3-. 30CrMoA has better resistance to stress corrosion in most experimental corrosion conditions better than 30Ni2CrMnMoVA. This provides a reference for the selection and use of high strength sucker rod.