Stress corrosion cracking of X-70 pipeline steels by eletropulsing treatment in near-neutral pH solution

Slow strain rate tests (SSRT) and environmental scanning electron microscopy (ESEM) were utilized to investigate stress corrosion cracking (SCC) behavior of electropulsed POSCO and Bao Steel X-70 pipeline steels specimens in XJ solution purged with 5% CO2 + 95% N2 at the strain rate of 2E-6/s. The results showed that the ultimate tensile strengths (UTS) were raised considerably for the electropulsed specimens. The UTS for electropulsed POSCO X-70 pipeline steel was enhanced much more compared to electropulsed Bao Steel X-70 pipeline steel. In addition, the relationship among UTS, the original grain size and high voltage in electropulsing treatment was revealed. SCC sensitivity increased with the decreasing electrochemical potential, especially at high cathodic potential.