Study of the Impact Toughness Values Scattering Mechanisms of Hot-Rolled Low-Carbon Low-Alloy Steel Based on the Results of Multiple Charpy Impact Tests

To determine the nature of the impact toughness values scattering during multiple Charpy impact tests, fractographic and microstructural studies of the fracture mechanisms of low-carbon, low-alloy hot-rolled steel samples were conducted. It was found that the factor determining the fracture mechanisms is the formation of martensite-bainite interlayers in the Mn, Si, and P axial segregation region. On one hand, these interlayers initiated transcrystalline cleavage, and on the other hand, they served as sites for grain-boundary splitting occurrence.