Influence of Inclusions on Hydrogen Induced Cracking of Oil Well Pipe Steel

Hydrogen induced cracking(HIC) tests in pH 2.0 corrosion solutions and inclusion analysis of oil well pipe steels were carried out. The mechanism of inclusion influence was discussed. The results showed that HIC sensitivity of the sample with more inclusions was the biggest in strong acidic solution. The inclusions which induced HIC were MnS inclusion, Al2O3 inclusion and SiO2-Al2O3 inclusion. Among the three kinds of inclusions, the strip-shaped MnS inclusion had the greatest harmfulness. The initial patter of HIC caused by inclusions was cavities around inclusions, and then cavities developed into cracks.