Abstract: Decarburization, inclusions, segregation and brittle fracture of hot rolled 60Si2Mn steel strip were analyzed by means of optical microscope, scanning electron microscope and electronic tensile testing machine. Microstructure and mechanical properties of the specimens near the brittle fracture and away from the fracture were characterized, and the brittle fracture characteristics and fracture behavior of hot rolled 60Si2Mn steel strip were investigated. The results show that there is no obvious decarburization, inclusion and segregation at the brittle fracture, and the fracture presents brittle fracture. The content of proeutectoid ferrite in the specimens near the brittle fracture and away from the fracture is 12.45% and 0.66%, respectively, and the pearlite lamellar spacing is 578 nm and 236 nm, respectively. The main cause of brittle fracture of hot rolled 60Si2Mn steel strip is that the content of proeutectoid ferrite in the brittle fracture is higher than that in the position away from the fracture, and the pearlite lamellar spacing is larger, which leads to poor resistance to deformation and is prone to uneven deformation during the rolling process. Additionally, the stress difference between the coarse ferrite and cementite layers can easily lead to brittle fracture, and the cracks propagate along the two-phase interface. However, the plastic deformation of fine pearlite is relatively uniform, and cracks propagate through the layers of pearlite.

Key words: hot rolled 60Si2Mn steel, brittle fracture, pearlite lamellar spacing, mechanical properties, crack propagation