H₂S stress corrosion invertigation of pipeline steel welded joints

The H₂S stress corrosion tests were conducted for the welded joints of X56 steel and X65 steel under various welding processes in order to investigate the susceptibility of weld metal and heat-affected zone(HAZ) to H₂S stress corrosion cracking(SCC),and the wedge-opening loading(WOL) specimens were used in the tests.The test results showed that small crack growth occurred in all specimens,and the crack stopped to grow when the stress intensity factor K reached the critical value(threshold stress intensity factor).In this paper,the H₂S stress corrosion resistance of HAZ was better than that of weld metal for the welded joints of X56 and X65 steel.In addition,the corrosion resistance of HAZ and weld metal were worse than that of base metal inferred to literature,which was caused by grain growth coarsening,welding residual stress of HAZ and weld metal,weld strength overmatching and welding defects.