Quantitative Study on the Threshold Stress of Hydrogen-induced Cracking for X80 Pipeline Steel

The threshold stress and fracture stress of hydrogen-induced cracking of X80 pipeline steel are studied by constant load test and slow stain rate test. The experimental results show that during dynamically charging X80 pipeline steel with hydrogen, the concentration of diffusible hydrogen C₀ is directly proportional to cathodic current \sqrti . Fracture stress during dynamically charging with hydrogen decrease with hydrogen concentration in slow stain rate tests. The threshold stress decreases linearly with the logarithm of hydrogen concentration for the samples in constant load tests, i. e, σ_HIC = 669-24 ln C₀.