Effect of hydrogen-induced plasticity on the stress corrosion cracking of X70 pipeline steel in simulated soil environments

Abstract The susceptibility to stress corrosion cracking (SCC) of X70 pipeline steel under cathodic protection in near-neutral pH and acidic solutions was investigated by slow-strain-rate tensile test, circumferential-notch tensile (CNT) test, and three-point-bending (TPB) test. Results confirmed the existence of a hydrogen-induced plasticity (HIP) effect within a particular range of cathodic potentials. HIP effect lowered the SCC risk of X70 steel by releasing stress concentration at crack-initiation spots and then decreasing the stress intensity. Crack-growth behavior examined by CNT and TPB tests proved the existence of an HIP effect.