Influence of Heat Treatment on Structure and Durometric Properties of Coatings Obtained by Surfacing with CSR-04СR27NI7MO3CU2Т Cast Rods

The effect of heat treatment modes on the structure and durometric properties of coatings obtained by surfacing with CSR-04СR27NI7MO3CU2Т cast rods, is considered. It is found that the temperature of 800°С and soaking time of 5 hours are optimal to increase the deposited metal hardness. It is shown that such a phenomenon results from the formation of the austenitic structure hardened by the precipitates of the σ-phase (FeCr), chromium carbides (Cr3C2) and titanium carbides (TiC). The heat treatment modes proposed can be applied in the wear-resistant surfacing technology of chemical equipment parts.

Microstructure and Properties of the 308LSi Austenitic Steel Produced by Plasma-MIG Deposition Welding with Layer-by-Layer Peening

This paper investigates the effect of cold working via layer-by-layer peening on the microstructure and properties of a 308LSi steel workpiece produced by the wire deposition welding with a consumable electrode following the principle of 3D printing. The microstructure, phase composition and mechanical properties of the metal are studied before and after the workpiece synthesis. In the microstructure of the workpieces produced by peening, there is, in addition to austenite, a small quantity of fine-dispersed carbides and residual δ-ferrite in the interdendritic spaces. It is demonstrated that the use of layer-by-layer cold working in the process of deposition welding enables eliminating transcrystallization of the deposited metal, promotes an increase in the microstructure’s degree of dispersion and a more uniform distribution of fine-dispersed carbides in the volume of the dendrites. It is found that these structural features of the deposited metal in the additive manufacturing of a workpiece with layer-by-layer peening lead to an enhancement of the strength characteristics as compared to the material produced by the conventional wire deposition welding. Meanwhile, the level of the ductility characteristics remains high.

Features of design, construction and technology of manufacturing galvanoplastic jewellery

The features of design, construction and manufacturing technology of electroplated jewellery are considered. The classification of jewellery made by the method of electroforming, based on their areas of application, is presented. The technological features of the formation of the surface of products with a “posi-tive” and “negative” build-up of the deposited metal, ways of reducing the roughness of the deposited coat-ings with an increase in their thickness are considered. Methods of creating suspension and fastening ele-ments of the product structure are described. The main modern trends in the development of technology and design of products made by the method of electroforming are considered: the use of 3D technologies in the development and creation of models, the use of conductive polymer compositions for the manufacture of models, computerization of the technological process of forming metal deposits of precious alloys of a cer-tain carat and colour. Modern technological methods allow raising the level of electroplated jewellery de-sign to a new level.

PREDICTION OF ULTRALOW CYCLE FATIGUE DAMAGE OF THIN-WALLED STEEL BRIDGE PIERS

Ultralow cycle fatigue (ULCF) failure was first observed on steel bridge piers in the Kobe earthquake, and the ultimate strength and ductility evaluation formulas of thin-walled steel bridge piers were established. In this study, parametric analysis of steel piers was carried out to study the influence of the structural parameters on the ULCF damage evolution. The evolution of the ULCF damage of the base metal, the deposited metal, and the heat-affected zones was studied based on two types of steel piers with hollow box and pipe sections. Then, practical formulas to predict the ULCF damage level of steel piers under cyclic loading were proposed. Finally, the proposed formulas were validated by comparisons with the experimental results. The results show that the heat-affected zone is more vulnerable to ULCF failure than the base metal and the deposited metal. Moreover, the practical formulas to predict the ULCF damage index of the steel piers under cyclic loading were proposed, and the formulas effectively predicted the ULCF crack of the steel piers.

The influence of the surface density of oriented nickel networks on the conducting electrode’s optical transparency

This study is part of the work on the creation of a transparent conductive coating based on oriented nanonetwork and submicron nickel fibres. It is devoted to finding the optimal values of electrical conductivity and optical transparency of the developed coating. In this work, we study the transmission spectra of oriented nickel networks on a glass substrate in the UV, visible and near-IR regions at different amounts of deposited metal. An exciting feature of the coating was discovered: in the range of 950 nm and above, there is a "bend" of the transmission spectrum downward. This bend (increased absorption of radiation in the near-IR region) is observed only in the presence of nickel nanonetwork and is not typical for a pure submicron network.

Transmission spectra of transparent electrodes based on oriented platinum nanowires at various concentrations of the metal used

The paper investigates the optical transparency dependence of a coating based on an oriented network of platinum nanowires on the amount of metal used. Oriented platinum nanowires on a glass surface are produced by chemical deposition from an aqueous hexachloroplatinic acid solution. The topography of the deposited metal layer on glass is visualized using atomic force microscopy. Optical transparency was investigated with a spectrophotometer. In almost the entire region of optical radiation, the transparency is approximately 98%. The absorption spectrum shows that the absorption coefficient increases sharply in the near UV region.

Research on Microstructure Evolution of Deposited Metal of Low Nickel High Nitrogen Austenitic Stainless Steel

In this paper, in situ observation of the cooling process of the deposited metal of low nickel high nitrogen austenitic stainless steel obtained by laser-arc hybrid surfacing welding with shielding gas containing only Ar and only N2, respectively, is carried out using the ultra-high-temperature confocal laser scanning microscope (CLSM). An in-depth analysis of the microstructural changes is conducted with SEM, EDS, and EBSD. The results showed that the surface substructure is refined during crystallization with shielding gas Ar. However, grains are seriously coarsened in the δ phase area. Widmanstatten γ and intragranular γ are formed as a result of δ ⟶ γ phase transition through the shear-diffusion mechanism. In the cooling process with shielding gas N2, the temperature range of each phase area narrowed obviously. Blocky γ began to appear because of the δ ⟶ γ phase transition through the diffusion mechanism. Generally, Ar and N2 have a strong effect only on the very shallow range from the surface. The area with a larger local misorientation with shielding gas Ar is at lath γ on the surface. With shielding gas N2, the large local misorientation area is the last contact position of γ during the δ ⟶ γ phase transition on the surface and cross section.

Formation of catalytic and corrosion protective layers with use of ion beam assisted deposition of metals from vacuum arc discharge plasma

This paper presents a brief overview of our studies on the modification of materials using ion beam assisted deposition (IBAD) of metals from vacuum arc discharge plasma in order to form catalytically active and corrosion-resistant layers on the surface. Deposition of metals on different materials with simultaneous mixing of the deposited layer with the substrate surface by accelerated ions of the deposited metal was carried out in an experimental setup with a pulsed electric arc ion source. Catalytic and corrosion properties of the materials with the obtained layers were studied using electrochemical voltammetric measurements. The microstructure and composition of the resulting layers were studied using the SEM, EDX, WD-XRF, XPS, EBSD, and RBS methods.