Mechanism research on layered fracture of hot rolling Ti-bearing HSLA plates

The reason for layered fracture about hot rolling Ti-bearing HSLA plate was studied by optical microscopy, electron backscattering diffraction and transmission electron microscopy. The results show that MnS and large grained Ti(C, N) complex precipitation and aggregation are the main causes when the microstructure and effective grain size are normal. The tensile fracture shows a quasi-cleavage morphology with tearing edges and shallow dimples. During plastic deformation, the microcrack initiation is attributed to the crushing of Ti(C, N). The cracks are conducted along the thin-film-like MnS, eventually forming tearing edges at Mns and matrix interface. A large number of parallel-distributed MnS inclusions act together, leading to layered fracture morphology during stretching. By reducing the content of S and N, it can effectively reduce the number of two types of inclusions, eliminate the phenomenon of fracture stratification, and improve the plastic index.