Mechanical properties of Q345 structural steel after pre-fatigue loading

This study investigates the residual mechanical properties of Q345 structural steel previously damaged by pre-fatigue loading. Fatigue damage is induced by subjecting Q345 structural specimens to various loading cycles without causing fracture under three pre-fatigue loading stress levels, which is referred to herein as pre-fatigue damage. Subsequently, tensile tests are performed on these specimens to obtain the stress–strain curves and associated parameters, including yield strength, ultimate strength, elastic modulus, and ductility. Based on the test results, the effect of pre-fatigue loading on the mechanical properties of Q345 structural steel is comprehensively discussed and analyzed. Significant differences are observed in the fracture positions and morphological features of the Q345 steel structure after pre-fatigue loading. Additionally, pre-fatigue loading significantly affects the residual strength and ductility of Q345 structural steel. In particular, the residual ductility of Q345 structural steel reduced significantly after being subjected to different cyclic loadings. However, the effect of pre-fatigue loading on the elastic modulus of Q345 structural steel is almost negligible.