Stress Corrosion Cracking of X80 Pipeline Steel in Near-Neutral pH Values Solutions

The stress corrosion cracking (SCC) behaviors of X80 pipeline steel in near-neutral pH solutions were studied using electrochemical potentiodynamic scanning,slow strain rate tension(SSRT) and scanning electron microscopy.Electrochemistry test results showed the polarization curves of X80 pipeline steel and welded joint in NS4 solutions have typical characteristics of active dissolution.SSRT result showed that with the negative increase of potential,the cracking time,reduction of area and dependent variable all decrease obviously,the sensitivity for SCC increases,and the cracking mode was transgranular with the feature of quasi-clea-vage.When the applied potentials of welded joint and base metal were the same,the welded joint was more sensitive than base metal in SCC.The results showed that all tensile test specimens crack in weld metal and heat affected zone(HAZ).