An experimental study on the corrosion behaviors and mechanical properties of Q345qD steel in neutral salt spray environment considering stress state

This paper investigates the corrosion behavior and mechanical property degradation of Q345qD steel in the marine atmosphere through force-holding neutral salt spray corrosion experiments. A digital microscope is utilized to obtain the surface morphology of corroded specimens. Mass losses and equivalent corrosion depths for different corrosion times and stress levels are quantitatively determined. Statistical laws of pitting corrosion are formulated based on digital microscope observations. Typical mechanical properties of corroded steel are also obtained through tensile tests. Results show that stress accelerates the pitting process but has little impact on the mass losses of general corrosion. The relationship between equivalent corrosion depth and corrosion time can be well described by a linear function. Corrosion can decrease the apparent strengths of Q345qD steel and trigger a transition from ductile fracture to brittle fracture. To ensure the safety and durability of engineering structures, a maximum mass loss ratio of 10% is suggested.