Stress Corrosion Behaviors of 4330 and 17-4PH Steels in HCl Solution

A comparative study of 4330 and 17-4PH steels for oil fracturing valve box was conducted to reveal their stress corrosion behaviors in 20% (mass fraction) HCl solution by Cring load stress corrosion test. The stress distribution of the C-ring samples was simulated by Abaqus finite element analysis method. The simulated results affirmed that the highest stress was obtained on the central area of the C-ring by constant displacement loading. The results show that the 4330 and 17-4PH steels display the high resistance on stress corrosion in the environment of 20% HCl solution and 120 MPa loading stress, which can meet the work requirements of no stress corrosion crack in 300 h. The stress corrosion behaviors of the two kinds of steels are general corrosion, the low content of C and high content of Cr, Ni, and Cu are the key factors for the improved stress corrosion resistance of 17-4PH steel, compared with 4330 steel. When the corrosion stress is increased to 400 MPa, the 17-4PH steel also exhibites good resistance to prefabricated crack propagation.