Vol 58, No 5-6 (2016)

Features of deformation regimes and mechanisms of microstructure formation in low-carbon steel 20 are studied using high-speed and multicycle hot plastic deformation methods in a Gleeble 3500 unit. Energy-force and temperature-speed regimes are established providing preparation of an ultrafine-grained structure with grain size of 150 – 1250 nm, similar to that achieved with higher degrees of cold plastic deformation. Specimen microhardness is determined.

Carbides in annealed steel H13 without magnesium and with a micro-addition of magnesium (0.0010%) are studied. Trace amounts of magnesium strengthen carbide segregation and reduce their size. Carbides phases M₇C₃, M₆ C, and M(C, N) are detected in steel H13, and this agrees with results of thermodynamic calculations.

Results are given for metallographic and x-ray diffraction analysis of the structure, degree of recrystallization, and preferred crystallographic orientations, and also mechanical and corrosion properties through the thickness of 100 mm thick rolled plates of high-strength aluminum alloy 1933, considered in this study as an alternative to forgings.

Wear resistance, corrosion properties and structure of reinforced layers deposited on steel AISI 321 with carbonitriding by the quench-polish-quench (QPQ) Tennifer® process with subsequent oxidation are studied. The structure of the layers is investigated by scanning electron microscopy with energy dispersive local analysis and x-ray diffractometry. Steel wear resistance is determined by a pin-on disk test, and oxide layer adhesion is determined by a scratch method. Pitting corrosion resistance is determined by plotting cyclic polarization curves.

The structure and fracture behavior of a layer of maraging alloy deposited by laser surfacing on steel 3Kh3M3F is studied in the initial condition and after precipitation hardening at 550 and 600°C. Microhardness is measured in layer cross sections, and fractures after surfacing and aging are analyzed in an electron microscope.

The properties of aluminum alloy AA6061-T6 after aging at 220°C for 0.5 – 8 h are studied by the methods of light and scanning electron microscopy and fractography. The mechanical characteristics of the alloy are determined by tensile tests.

On the basis of metallographic monitoring of semimanufactured steel pieces and automobile parts, it is shown that prediction of the properties of articles on the basis of the criterion of microhardness of individual structural constituents and the difference in the values of the criterion represents an effective approach.

Some features are provide for the change in structure and properties of commercial purity titanium during hydrogenation and their effect on formation of the final structure of semifinished products and objects after vacuum annealing. It is established that titanium hydrogenation kinetics by a thermal diffusion method and specimen structure formation are mainly determined by the temperature for introducing hydrogen.

The microstructure and mechanical properties of thick-walled joints of Al – Mg – Sc alloy 1570S, prepared by friction stir welding are studied. Joint microstructural and mechanical inhomogeneity are revealed.

The effect of cooling medium on the microstructure and mechanical properties of steel 30CrMnSi is studied after different heat treatment. Microstructure is studied by scanning electron microscopy, energy dispersion analysis, and fractography. Impact strength, shear punch stress, friction coefficient, and wear resistance in pin-on-disk tests are determined. Phase transformations with tempering are studied by dilatometry. A heat treatment regime providing an optimum set of steel properties is proposed.

A study is made of complexly alloyed steel 8Kh4V9F2-Sh, which is used for fabricating parts of engineering bearings operating under extreme conditions. Vacuum processes are shown to be preferable to gas carburizing for hardening the races of precision bearings. Vacuum carburizing is shown to be an effective technique for forming quality diffusion layers.

Causes for the failure of pig iron press molds that are parts of a glass mold are described. Criteria for differentiating the structure of pig iron are established. Ways of obtaining a differentiated structure of a casting product are outlined. A heat treatment regime for the billets is determined.

The historical aspect is provided for research into the effect of a magnetic field and a number of other actions on martensitic transformation in steels and alloys.

Chromium-nickel and high-manganese steels are studied. The specific magnetic susceptibility χ₀ of paramagnetic austenite is shown by experiment to depend on nickel content in chromium-nickel steels and on manganese in manganese steels subjected to compressive deformation. It is shown that with an increase in nickel content, apart from structural stabilization of austenite, there is an increase in χ₀. The effect of manganese on parameter χ₀ in manganese steels is the opposite. Localized distribution of Cr and Ni elements and presence of regions of a ferromagnetic phase at austenite grain boundaries in chromium-nickel steels is revealed.