The effects of chemical composition, melting process (open-hearth, electric arc furnace), melting unit operation volume (2 × 10 2 kg, 3 × 10 4 kg, 25 × 10 4 kg), deformation process (band, wheel) and heat treatment process on the properties of carbon steels have been investigated. The results of determining the inclination of steels no. 30, 50, and У7 to brittle fracture as well as the results of bending fatigue, impact fatigue and thermal fatigue tests have shown the advantage of steel no. 50, which is characterized by minimum solubility of hydrogen. It was found that periodically there were some low values of impact toughness at 293 K for open-hearth processed steel with carbon content above 0.6%. Structure and properties of high-carbon steel after heating below A I have been investigated. The application of micro-structural analysis allowed to explain the reduction in KCU value by the internal pressure of molecular hydrogen and methane in steel.