Comparative study on mechanical and corrosion fatigue properties of high-strength bridge steels produced by TMCP and intercritical quenching & tempering process

The mechanical and corrosion fatigue properties of Q690 bridge steels produced by two different process were comparatively investigated. The steel produced by thermal-mechanical controlled processing (TMCP) and tempering had a slightly superior corrosion fatigue property to that produced by intercritical quenching & tempering (IQT). However, the TMCP + T prepared steel had a poor ductility and corrosion fatigue microcracks were prone to initiate due to high density of dislocations and M/A constituents. On the contrary, the steel produced by IQT had a good combination of mechanical and corrosion fatigue property. The corrosion fatigue initiation and propagation mechanism for both steels was proposed.