Study on Mechanical Behaviours and Microstructure Features of Q690 Steel Weldments with Various Electrochemical Hydrogen Charging Conditions

Regarding the application of high-strength steel welded components to large marine equipment, prolonged exposure to marine environments results in the infiltration of hydrogen, leading to a significant decline in mechanical performance. In this study, the electrochemical hydrogenation characteristics of Q690 high-strength steel welded components at room temperature are examined under various conditions to investigate their mechanical properties. The welded specimens initially undergo electrochemical hydrogenation and, subsequently, uniaxial tensile testing to explore the influences of hydrogenation methods on their mechanical properties such as tensile strength, yield strength, and elongation after fracture. X-ray diffraction (XRD) and scanning electron microscopy (SEM) are utilized to observe changes in the microstructure features in heat-affected zones (HAZs) and highlight the mechanisms affecting material mechanical properties. The results indicate that the tensile strength, yield strength, and elongation after fracture of the material decrease with increasing hydrogenation time, solution concentration, and current density. Moreover, the fracture modes of Q690 high-strength steel welded components shift from ductile fracture to brittle fracture with increasing hydrogen atom penetration.