THE THRESHOLD STRESS FOR HYDSOGEN-INDUCED CRACKING OF C90 TUBULAR STEELS

During dynamically charging four kinds of C90 tubular steels with hydrogen,the concentration of divisible hydrogen c0 is directly proportional to cathodic current i, and thenormalized threshold stress σc.(H)/σt decreases linearly with hi c0, i.e., σc(H)/σt=A-B ln c0.The concentrations of diffusible hydrogen in the steels during immersing in the H2S saturationsolution, c0*, have been measured. The values of σc(H)/σt during dynamically charging withic corresponding to c0* for the four steels are consistent with the threshold stress σc(H2S)/ctduring SCC in H2S solution. The result shows that the threshold stress during charging with asuitable current density ic can substitute for the threshold stress during SCC in H2S solution.