Effect of Bainite Crystallographic Texture on Failure of Pipe Steel Sheets Made by Controlled Thermomechanical Treatment

The method of orientation microscopy (EBSD) is used to study the texture of low-carbon, low-alloy pipe steel sheets with a bainitic structure made by controlled thermomechanical processing. The specimens analyzed are inclined or not inclined towards forming separations (secondary cracks) in a fracture during mechanical testing. Formation of separations during failure of steel with a bainitic structure is connected with the presence in the material of regions with uniform orientation (001) extended in the cold rolling direction. Formation of the regions is a consequence of features of γ→α shear transformation that commences at special boundaries between deformed austenite grains.