Experimental study on mechanical properties and toughness of Q460C high-strength steel and its butt welded joint at low temperature

Compared with the conventional steel structure, the high-strength steel structures are at more risk of brittle fracture, especially in cold regions. In the present study, a series of tests (such as uniaxial tensile test, Charpy impact test and three-point bending test) were carried out at low temperature to investigate the mechanical properties and toughness of Q460C steel and its butt welded joint, fracture micro-mechanisms were analyzed as well. The ductility indices and the toughness indices all decrease with temperature decreases, the heat affected zone (HAZ) in welded joint is more critical to fracture than the base material. The fracture toughness of high-strength steel Q460C is relatively lower than the other three conventional steels (i.e. Q235, Q345 and Q390). In this study, rich experimental data were collected so as to provide reference for the fracture resistant design of high-strength steel structures in cold regions.