Structural Anisotropy Parameters' Effect on the Low-Temperature Impact Strength of Alloy Steels in Rolled Products

The present work is devoted to the study of the influence of the parameters of the structural anisotropy of rolled products on the low-temperature impact strength of alloyed steels. A quantitative metallographic analysis of the microstructure of rolled steel samples obtained after testing for low-temperature toughness was carried out. It was established that the main reason for the decrease in the low-temperature impact strength of rolled steel samples is a highly developed segregation band enriched with carbon films formed at the stage of steelmaking conversion in violation of the technology of continuous casting of steel. The microstructural analysis of rolled stock samples was used in the work, and studies of the fracture surface of rolled stock samples were carried out with a scanning electron microscope using X-ray microanalysis methods. The studies carried out showed that the metallurgical quality of sheets of one heat, as well as individual samples within one sheet, varied over a wide range, from satisfactory to unacceptably low. It was established that the main reason for the decreasing low-temperature impact strength of rolled products was a highly developed segregation band enriched with carbon films, formed at the stage of steelmaking in case of violation of the continuous casting of steel technology. The multivariate statistical analysis carried out showed that only the size of the segregation band has an effect on the low-temperature impact strength of 10 mm thick rolled coil samples.