Research on the constitutive relation of different material zones of weathering steel Q355GNHB

To research the mechanical properties and low cycle fatigue performance of Q355B structural steel and Q355GNHB weathering steel, this study performs monotonic and cyclic tests on the base metal, welded metal and heat-affected zone (HAZ) of Q355GNHB welded connections and Q355B. The monotone and cyclic constitutive model parameters are calibrated using the true stress-strain relationship and the Chaboche hybrid strengthening model, and their accuracy is verified by ABAQUS. To streamline the calibration process, a simplified calibration method is established for the Chaboche combined hardening model. Compared to the traditional calibration method, the proposed method uses the stress-strain data obtained from the monotonic tests. The applicability of the calibrated model is verified by simulating the tests via ABAQUS. The research results show that both Q355B structural steel and Q355GNHB weathering steel have excellent bearing capacity and plastic deformation capacity. The Q355GNHB weathering steel has better ductility, while the Q355B structural steel has higher bearing capacity and stronger strength reserve capacity. The strength of Q355GNHB varies according to different zones: the yield strength of the base metal material is the lowest, while the tensile strength and the plastic deformation capacity of the welded metal material is the lowest. Besides, the Chaboche combined hardening model and simplified combined hardening model can capture the cyclic fatigue performance of Q355B and Q355GNHB steel. The research results provide effective data support for the in-depth study of the constitutive relations and mechanical properties of weathering steel materials and the accurate simulation of the properties of weathering steel structures.