Effect of Water Environment on Fatigue Behavior in X80 High Strength Steel CO2 Arc Welding Welded Joint

Fatigue life tests and fatigue crack growth rate (FCGR) in the air water environment were conducted on X80 pipeline steel welded joints (welded by CO2 arc welding). Scanning electron microscope (SEM) backscatter diffraction (EBSD) utilized to investigate internal influential mechanisms of during initiation propagation stages, respectively. Results show that a great many oxide particles induced gradually formed site decreased joints. Meanwhile, preferred grain orientation <001>//ND CSL boundaries Σ3, Σ11, Σ13c, Σ17b, Σ25a, Σ25b are both prone when loading environment. In addition, coalescence stress intensity factor (SIF) range accelerated FCGR motivating secondary slip systems {112}<111> {123}<111> bcc crystalline structures.