Hydrogen Sulfide Stress Cracking in a Q345R Welded Joint

In this paper the failure reason of Q345R Welded Joint was studied through macroscopic observation, chemical properties, metallurgical analysis, scanning electron microscope (SEM) and EDS test method. The results showed that there were a large number of micro-cracks in the fracture surface. The reason of cracking is severe banded structure in base metal microstructure, which provided opportunity for hydrogen atoms to enter into the internal of steel when contact with wet hydrogen sulfide environment. The existence of tensile stress promotes the entry of hydrogen atoms and the propagation of cracks. The welding products of this procedure are not suitable for use under sour conditions.