Kyono Yasuda

Effect of Cu Addition in Pipeline Steels on Prevention of Hydrogen Permeation in Mildly Sour Environments

In this study, the influence of Cu addition on hydrogen entry behavior was investigated with the aim of preventing hydrogen-induced cracking (HIC) in mildly sour environments in which the solution ...

Effect of Cu on Hydrogen Permeation for the Low Carbon Steel under Mildly Sour Environments

Hydrogen Induced Cracking (HIC) and Sulfide Stress Cracking (SSC) are the major issue for low carbon alloyed steels applied to sour line pipes at oil and natural gas fileds. It is caused by the presence of hydrogen sulfide, which enhances hydrogen entry into steels and causes the environmental cracking. It is well known that Cu is effective element for preventing HIC in mildly sour environments in which the solution pH is more than 5.0[1]. However, the mechanism of Cu rolls on HIC prevention has not been fully clarified. It was found that Cu addition remarkably decreased hydrogen entry into steel[2] and Cu was enriched in the corrosion product based on EPMA micron order analysis [3]. In present paper, corrosion test under H2S environments are carried out with measuring the amount of hydrogen permeation. Microstructural morphologies of corrosion products, especially Cu distribution and morphologies are investigated through FIB/SEM and STEM analysis for understanding its rolls on preventing the corrosions.