Reason Analysis on Hydrogen Induced Crack and Hydrogen Induced Blister in Steel for Sour Service

The optical and electrical microscopy observation has been done on the sample of steel pipeline for sour service, after the HIC test according to NACE TM0284-2003 standard. It was found that the shape of hydrogen induced crack was diversity, including stepwise, single, Y shape, etc. And it was found that the hydrogen induced blister on sample surface was hydrogen induce crack actually, but no matter hydrogen induced crack or blister, crack all originated on the banding, inclusion or coarse grain boundary. By well control of technology, banding and inclusion reduced to a proper level, and the hydrogen induced crack eliminated finally.