The article considers the problem of effective and high-quality restoration of road construction machines and equipment. Operational features of reliable and high-precision equipment for road and construction works require high costs for maintaining the operability of machines. Since mainly foreign-made equipment is used, replacing worn-out, especially functionally important parts is very costly. To ensure the requirements of reliable and safe operation of road construction machines, a systematic approach to solving these problems is required, which is decided by the authors through developing an original model of the optimal choice of energy efficient technology for the restoration of parts of road construction machines, with the goal being the highest quality of the part after restoration.

Introduction: During experimental studies of structural steels responsible for the reliability of metal structures used, for example, in hoisting and transporting machinery, we established a correlation between the magnetic parameter Hp and characteristic changes in the metal microstructure during thermal cycling. It is shown that the Нр parameter depends on the initial structural state of steel, the amount and mass fraction of alloying elements, and the number of heating/cooling cycles. Methods: We found that an increase in the number of heating/cooling cycles and the amount of alloying elements, as well as preliminary cold plastic deformation with stage-by-stage control of structural changes using passive magnetic flux leakage testing results in a finer-grained structure, which was confirmed by metallographic analysis. Results: The paper considers specifics of structural changes in steels with different initial structures during thermal cycling. It is shown that the final grain size depends on the number of treatment cycles, the amount of alloying elements, and the initial microstructure. It is the fine-grain structure that improves the most important performance characteristics of steels: strength, cyclic strength, and cold brittleness.

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The analysis and consideration of the influence of the main factors on the damage of welded metal structures during long-term operation. The relationship between the strength of the magnetic field of the Hр scattering and structural changes in structural steels that occur during cold plastic deformation to different degrees is established. It is shown that at small degrees of deformation, the change in the magnetic parameter Hр is large. As they increase, the HP value decreases and tends to the values of the Earth's magnetic field. The data of microstructural analysis of the metal of structural steels are in good agreement with the results of the passive ferrosonde method of control. A method for evaluating the effect of cold plastic deformation on the magnetic properties of metal in structural steels has been developed.

The analysis of the main factors affecting the reliability and safety of welded metal structures in long-term operation is carried out. The features of obtaining a fine-grained structure due to recrystallization annealing and the main factors affecting the degree of dispersion of the formed microstructure are considered. For low-carbon steel 08ps and low-alloy steel 09G2S, optimal recrystallization annealing regimes have been developed with the aim of obtaining final structures with a given degree of dispersion, typical for real building metal structures. It was found that the degree of dispersion of the obtained microstructures depends on the heating temperature, the initial structure, and the chemical composition of the steels.