Influence of Residual Tensile Stress on Stress Corrosion Behavior of the Base Metal of X80 Pipe
The influence of residual stress on stress corrosion behavior was studied by way of SSRT test on the base metal of X80 pipe with different residual tensile stress in the simulating soil environment aqueous solution; and the electrochemical test techniques were adopted to test the effect of the residual stress on electrochemical polarization behavior and AC impedance characteristics of the base metal. It is shown that the base metal specimens without introducing the residual stress of X80 UOE pipe and X80 SAWH pipe have different stress corrosion sensitivity in this solution. The base metal specimens with different residual stress of X80 pipe only occurs the anodic metal dissolution reaction on the material surface in this kind of solution without forming the passive film. The residual tensile stress leads to the increase of the electrochemical activity and the reduction of impedance of the base metal surface of X80 pipe, and it accelerates the nucleation and early propagation of the stress corrosion crack, which promotes the SCC sensitivity of the base metal.