Abstract
The hydrogen cracking susceptibility of mild steel was studied to determine the overprotection potential in soil and acetic acid solution by slow strain rate test (SSRT), constant load test and hydrogen permeation test.
The following results were obtained:
(1) The elongation was tend to decrease and the tensile strength was tend to increase in the overprotection environment compared with air environment.
(2) The reduction of area did not decreased in 20% water content soil under overprotection conditions.
(3) The reduction of area decreased in 30% water content soil with shifting less noble potential, and also SEM photograph indicated quasi-cleavage fracture surface.
(4) Mild steel exhibited hydrogen cracking susceptibility when hydrogen content was more than 10 ppb. The cathodic potentials, which cause hydrogen cracking susceptibility, were -1.4V (vs. Cu/CuSO4) in 30% water content marine clay and -1.2V in 14% water content sand, respectively.
