Effects of Temperature and Applied Potential on the Stress Corrosion Cracking of X80 Steel in a Xinzhou Simulated Soil Solution.

Abstract

In this research, the stress corrosion cracking (SCC) behavior of X80 pipeline steel in a Xinzhou soil environment at different temperatures and applied potentials was studied with a slow strain rate test (SSRT), potentiodynamic polarization curve measurements, and scanning electron microscopy (SEM). When a higher anodic potential was applied, anodic dissolution occurred at the crack tip and on the crack wall. The cracking mechanism of X80 steel in Xinzhou soil solution is anodic dissolution (AD). At positive cathodic potentials, X80 steel is under an anodic polarization state at the crack tip and under a cathodic polarization state at the crack wall. The SCC of X80 steel is affected by the combined effects of anodic dissolution (AD) and hydrogen embrittlement (HE). At more negative cathodic potentials, both crack tips and crack walls are under cathodic polarization. The SCC of X80 steel is dominated by hydrogen embrittlement (HE). SCC susceptibility has the same variation trend with potentials at different temperatures. The susceptibility to SCC increases notably as the temperature increases at weak cathodic potentials and open circuit potential due to the effect of temperature on the corrosion potential and the diffusion of atoms.