Determination of Critical Factors Affecting on Hydrogen Induced Cracking and Type I Sulfide Stress Cracking of High Strength Linepipe Steel

摘要

The metallurgical factors affecting HIC and SOHIC of high strength linepipe steel are investigated and the cracking resistance is correlated with diffusible hydrogen. Internal cracks were initiated at elongated MnS and TiNb(C,N) cluster regardless of the cracking mode. Increase in diffusible hydrogen content by cathodic charging or applying the external load makes the steel more susceptible to the cracking and it can imply that both of critical factors, inclusion clusters as well as diffusible hydrogen in the steel, should be carefully controlled to improve the cracking resistance.