Microstructure in low-carbon low-alloy high-strength pipe steel

The microstructure of a broad range of low-carbon low-alloy high-strength pipe steels produced by thermomechanical treatment is studied by transmission electron microscopy. Such steels consist of a mixture of various types of ferrite matrix with high-carbon phases and structural components. The classification of the structures is refined, with separate consideration of the components forming the low-carbon ferrite matrix and the high-carbon components that appear as isolated regions and also as layers and inclusions in bainitic ferrite. A deformational dilatometer is used to determine the temperatures ranges in which the various phases and structural components are formed.