Novel Cu-bearing high-strength pipeline steels with excellent resistance to hydrogen-induced cracking

摘要

There is a great challenge to simultaneously improve strength and resistance to hydrogen-induced cracking (HIC) for pipeline steels. In this study, through copper (Cu) alloying, a novel type of pipeline steel was developed to meet the requirement for both high strength and excellent resistance to HIC The HIC tests of the tentative pipeline steels and the comparison steel were conducted in a hydrogen sulfide (H_2S) saturated solution according to NACE standard. The results showed that an aticular ferrite microstructure with uniformly distributed fine Cu-rich precipitates was obtained by aging at 500 ℃ for 1 h. Nano-scale Cu-rich precipitates in the new steels were speculated to play a significant role in making precipitation strengthening and providing beneficial hydrogen traps. The Cu-bearing pipeline steel has achieved a high strength grade of API X 120 with excellent resistance to HIC.