International Scientific Journals
of Scientific Technical Union of Mechanical Engineering "Industry 4.0"

The structure and mechanical properties of the oxide films formed on zirconium alloys Zr – 1% Nb, Zr – 2,5% Nb upon autoclave tests at a temperature of 360^oC and pressure of 18,6 MPa for 600 days were studied. Basic methodological approaches to the study of the structure and properties of thin oxide films were shown. The 10-15 µm thick oxide films of different structural types were shown to be formed on the specimens: the structures with predominately elongated grains and the layered structures. The structure of the oxide films subjected to loading determines both the crack formation stress and the character of fracture.

Analysis of material condition of side frames of freight trucks before and after thermal hardening was performed by combined analysis of Acoustic Emission (AE) and strain diagrams during tests of samples cut from the frames. The kinetic of damage accumulation during loading to failure in the material after normalizing or volume-surface hardening was analyzed. Changes in ductility and toughness resource of the metal was evaluated.

Testing method for static crack resistance has been developed and applied for thin sheet (sample thickness ~ 1mm) samples of zirconium alloy Zr-2.5%Nb. Linear parameter of fracture mechanics – stress intensity factor Kc has been determined. Alloy Zr-2.5%Nb after ECAP was tested for corrosion resistance in the physiological Ringer’s solution for two years.

The complex technique for study of the structure in Nb₃Sn-based composite superconductors is developed. Technique is based on scanning and transmission electron microscopy on different scale levels. The possibility of using the method of focused ion beam for TEM sample preparation is confirmed.

A new class of die steels for hot deformation, namely, steels with regulated austenitic transformation realized during exploitation (RATE) have been developed in Russia. These steels are characterized by the technological advantages typical of traditional α-solid solution-based steels and, when working in the austenite state, assure the enhanced tool life. The structure, phase composition and hardening of RATE steel have been analyzed by an example of steel containing 0.41 % C, 1.04 % Si, 3.59 % Mn, 2.41 % Cr, 5.07 % Ni, 2.40 % Mo, 0.69 % V, 0.51 % Ti, 0.25 % Co subjected to thermomechanical treatment, which includes the austenization and multiple plastic deformation. The nanophase hardening occurs in RATE steels being in the austenitic state, during multiple plastic deformation at temperatures of 450-750 °C. The precipitation of nano-sized heat-resistant excess phases ensures the inhibition of recrystallization processes at operating temperatures, inhibits the grain growth, and increases the stability of the austenite.