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This study investigates the influence of various microalloying systems (Nb–V–Ti, V–Nb–Ti, V‒N, V–Ti–N, V–Ti) of low-carbon pipe steels on the formation of the microstructure, fine structure, and deposition of dispersive particles in rolled items produced under conditions of endless strip production (ESP) at Vyksa Steel Works in accordance with a combined procedure of melting, casting into thin slab (with the thickness of 90 mm), direct rolling with subsequent accelerated cooling, and coiling into a roll. It has been demonstrated that addition of titanium into steel leads to the formation of particles in austenite region. These particles are coarser in steels with titanium and niobium. In steels with higher nitrogen content fine interphase particles are formed, which are not observed in systems with Nb, V, and Ti. In steels of the Nb–V–Ti, and V‒Nb–Ti microalloying systems no particles with vanadium are observed.

The research results of the nitrogen and vanadium influence on the microstructure, fine structure formation and mechanical properties of low-carbon steel pipe are considered. It is shown that it is possible to obtain cold-resistant mill products with strength classes from K48 to K60 with high (26–29%) percentage of elongation by dispersion hardening due to the precipitation of vanadium particles together with hardening of a manganese solid solution in the conditions of the Vyksa Metallurgical Plant casting and rolling complex.

The microstructure, fine structure, and mechanical properties of high-strength low-alloy steel with boron are studied after two different rolling technologies: (1) high-temperature hot rolling; (2) two-stage controlled rolling with accelerated cooling and subsequent quenching with tempering. The tempering temperature corresponding to irreversible tempering brittleness of the first kind is established. The reasons for embrittlement at that temperature are analyzed.

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.