| Title |
Sulfide Stress Corrosion Behavior of X65 Line - Pipe Steels |
| Authors |
노광섭(Kwang Seop Ro),김병훈(Byoung Hun Kim),이창순(Chang Sun Lee),최용(Yong Choi) |
| Abstract |
Sulfide stress corrosion cracking (SSCC) behavior of X65 line-pipe steels was studied by a constant elongation rate test method to understand the sulfide stress corrosion mechanism. The SSCC test was carried out in aqueous acetic acid solution containing chloride ion in the strain rate range of 5×10^5∼5×10^7 sec^(-1). The corrosion potential and the corrosion rate in the aqueous solution were -580 mV_(SHI) and 4.2×10³ Acm^(-2), respectively. Degradation of the mechanical properties such as yield strength and ultimate tensile strength was observed during SSCC test. The SSCC resistance expressed by relative fracture energy ratio decreased from 55% to 13.5% at an open circuit potential of -580 mV_(SHI) as the strain rate decreased from 5×10^5 to 5×10^(-7)/sec. Anodic or cathodic polarization at about 100 mV resulted in reducing the SSCC resistance, which was explained by a model related to anodic dissolution and hydrogen embrittlement. The brittle fracture surface with intergranular and transgranular cracking was observed. The corrosion products on the failed surface were the mixture of iron oxide and sulfide. |