High ductile fracture of a low-yield-strength steel with a part-through curve crack

Abstract

Low-yield-strength (LYS) steels possess ultra-high ductility and low yield ratio which indicates a wide prospect of the application for energy absorption. When a LYS steel-based damper or buffer is activated by a seismic wave or a crash impact, the structural integrity usually has a high risk of failure. Hence, the fracture resistance of LYS steels should be a key parameter for their structural design and integrity assessment. Here, we report both an experimental and a numerical investigation on the fracture behavior of an LYS steel with the yield stress of 100 MPa (LYS100), where a part-through corner or surface crack is machined in specimens and the critical loading capacities of the specimens are determined by our experiments. The suitable material parameters of the extended finite element method for LYS100 are determined based on our experimental results, which can be used to describe the fracture behavior of LYS100. Our results show that the fracture toughness of LYS100 can be up to around 1019 N/mm, which is almost twice as high as that of Q235 and one order bigger than that of gray cast iron. These findings will be a great help toward understanding the fracture properties of LYS steels and designing high-performance damping structures.