Quantitative assessment of structural inhomogeneity in cold-resistant low-alloy steel sheets for interpretation of technological features of their manufacturing

Microstructural inhomogeneity comparative automated complex analysis of plate low-alloy cold-resistant steels for Arctic application with a thickness of 25, 50 and 70 mm, produced by thermomechanical processing technology with various temperaturedeformation parameters, has been performed. The inhomogeneity of the microstructure over the plates thickness was estimated by the volume fraction of coarse packet-block regions of lath bainite and regions of bainite that does not have a developed internal subgrain structure (conventionally called “non-granular” bainite), as well as anisotropy of the microstructure at different dimensional levels: short and long distance neighborhoods. The obtained results of microstructural heterogeneity quantitative assessment over the plates thickness were used for its detailed interpretation, taking into account the metallurgical inheritance of the slab and special features of two-stage thermomechanical processing with accelerated cooling.