Effect of Microstructure on Hydrogen Induced Cracking Behavior of a High Deformability Pipeline Steel

The hydrogen induced cracking (HIC) behavior of a high deformability pipeline steel was investigated with three different dual-phase microstructures, ferrite and bainite (F+B), ferrite and martensite/austenite islands (F+M/A) and ferrite and martensite (F+M), respectively. The HIC test was conducted in hydrogen sulfide (H2S)-saturated solution. The results showed that the steels with F+B and F+M/A dual-phase microstructures had both higher deformability and better HIC resistance, whereas the harder martensite phase in F+M microstructure was responsible for the worst HIC resistance. The band-like hard phase in dual-phase microstructure was believed to lead to increasing susceptibility to HIC.