


Vol 58, No 3-4 (2016)
- Year: 2016
- Articles: 22
- URL: https://journals.rcsi.science/0026-0673/issue/view/14634
Structural Steels
Effect of Dendritic Segregation on the Structure and Mechanical Properties of Hot-Deformed Pipes from Steel 38KhN3MFA
Abstract
The effect of dendritic segregation on mechanical properties of specimens cut from templates of two different batches of hot-deformed pipes from steel 38KhN3MFAis investigated. Comparative analysis of the results of mechanical tests and metallographic and x-ray spectrum studies of specimens with satisfactory and unsatisfactory macrostructures are performed, and the results are used to estimate the influence of intracrystalline inhomogeneity on the mechanical properties of ready articles from steel 38KhN3MFA.



Article
A Study of the Microstructure and Mechanical Properties of Medium-Carbon Steel 40KhGNM After Warm Swaging
Abstract
The effect of the temperature and degree of deformation during warm swaging on the evolution of the microstructure and mechanical properties of preliminarily quenched medium-carbon steel 40KhGNM is studied. It is shown that the deformation produces an ultrafine-grained structure with ferrite grains elongated over the longitudinal direction and fine distributed nanocarbides.



Effect of Microstructure and Segregation of Elements on the Impact Toughness of High-Strength Low-Carbon Bainitic Steel
Abstract
The impact toughness, microstructure and distribution of elements over the thickness of a plate from high-strength low-carbon bainitic steel are studied with the use of the methods of EPMA and EBSD. The causes of low impact toughness of the high-strength steel are analyzed.



Estimation of the Quality of Gas Laser Sawing of Sheets of Aluminum Alloys
Abstract
The effect of gas laser sawing on the properties of the cut edges of aluminum alloys is studied. Recommendations on application of gas laser sawing are developed. The main criteria for estimating the optimum speed of gas laser sawing of aluminum alloys are determined.



3-D Simulation of the Structural State of Single-Phase Solid Solutions of α-Titanium Alloys
Abstract
A 3-D model of an equilibrium polyhedral structure of a homogeneous solid solution is presented for α-titanium alloys. The variety of shapes and sizes of polygons is considered and arbitrary sections of a plane mapping of the spatial model are constructed. An analytical dependence relating the specified size of a crystallite to the mean diameter of its plane mapping is obtained. Relations between the specific surface, specific volume and the size of a crystallite at the micro-, submicro- and nanostructural (0.01 – 100 μm) levels are derived.



New Approach to Electron Beam Synthesis of Powder and Composite Materials. Part 2. Practical Results for Alloy VT6
Abstract
The prospects of industrial application of the process of electron beam synthesis for fabricating powder and composite materials for the production of critical parts are proved experimentally. The new process is tested on titanium and titanium-molybdenum alloys and is shown to provide materials with homogeneous structure and high operating properties.



Structural Changes on the Surface of Alloy Ti6Al7Nb Under Gas Nitriding
Abstract
The structure of titanium alloy Ti6Al7Nb (the surface nitride layer, the intermediate layer and the diffusion layer) is studied after nitriding at 950, 1120 and 1250°C for 12 h at atmospheric nitrogen pressure. The thickness of the nitride and diffusion layers is shown to increase with increase in the nitriding temperature. The growth of the nitride layer is accompanied by segregation of aluminum in the intermediate layer.



Effect of Aging on the Microstructure and Mechanical Properties of Magnesium Alloy AZ31
Abstract
The structure and mechanical properties of magnesium alloy AZ31 are studied after conventional and deformation aging under conditions corresponding to the thermal cycle of polymerization in paint coating of cars. The aging is conducted after 3-h solution treatment at 400°C, water quenching, and aging at 180°C for from 10 min to 6 h. Some of the specimens are deformed by 0.5% right after the solution treatment and then aged by the same regime.



End-Quenching Test as a Means for Assessing the Hardenability of Cast Iron
Abstract
A method of assessment of cooling rates in quenching of iron, which involves a standard end-quenching test, is applied to castings of VCh50 iron. The approach is shown to be effective for quenching of cast iron with pearlitic metallic matrix, for solving various technological problems and developing chemical compositions of ductile irons.



Effect of Modes of Homogenization of Ingots on the Microstructure, Phase Composition and Mechanical Properties of Alloy 01570 at Elevated Temperatures
Abstract
The effect of heat treatment of aluminum alloy 01570 on the microstructure, phase composition and mechanical properties of an ingot at elevated temperatures is studied. An optimum mode of heat treatment raising the strength properties of alloy 01570 at good ductility in the range of elevated temperatures is suggested.






Effect of the Aging Temperature of Steel on the Parameters of Fatigue Resistance and Microstrain
Abstract
The interrelation of the parameters of microplastic strain, the slope of the left-hand branch of the fatigue curve, and the fatigue limit of a maraging steel is studied. The growth in the microplastic strain is shown to match the growth in the fatigue limit and the decrease in the slope of the left-hand branch of the fatigue curve. The strength of the steel decreases with decrease in the temperature of post-quenching aging.



Chrome Aluminized Layers with Participation of Titanium Nitride on Steel 12Kh18N10T
Abstract
The possibility of deposition of multilayer coatings with regions of titanium nitride on the surface of steel 12Kh18N10T by physical precipitation from a gas phase followed by diffusion chrome aluminizing is shown. The phase and chemical compositions, the thickness, and the microhardness of the coatings are determined. The TiN nitride is shown to exhibit barrier properties and to lower the diffusion penetration of chromium and aluminum into the matrix and of iron and titanium into the coating under subsequent chrome aluminizing.



Aluminum Alloys
Effect of Rolling on High-Cycle Fatigue and Fracture of an Al – Mg – Sc Alloy
Abstract
The tensile strength and fatigue properties of alloy 1575 of the Al – Mg – Sc system are studied after hot deformation (at 360°C) and subsequent cold rolling with different reduction ratios. The effect of the deformed structure on the properties and mechanisms of fracture of the alloy under cyclic tests is determined.



Theoretical and Experimental Study of the Al – Cu – Si – Sn Phase Diagram in the Range of Aluminum Alloys
Abstract
Phase compositions of aluminum alloys of the Al – Cu – Si – Sn system are studied by computational and experimental methods. The computations are performed with the use of the Thermo-Calc software; the experimental part is implemented with the use of light and scanning electron microscopy, microscopic x-ray spectrum and thermal analyses. According to the computation, the quaternary system may exhibit layering of liquid and occurrence of monotectic transformations including a five-phase nonvariant one. The solidus temperature of the quaternary alloys depends little on the presence of copper and silicon and virtually coincides with the melting temperature of pure tin. The solubility of tin in the aluminum solid solution and in the (Si) and Al2Cu phases is negligibly low. Heating at 500°C changes substantially the morphology of the tin phase.



Titanium Alloys
Quantitative Analysis of the Phase Composition of the Ti – Al – Mo – V – Zr System as Applied to Castable Titanium Alloy VT20L
Abstract
Quantitative analysis of the phase composition of the Ti – Al – Mo – V – Zr system is performed as applied to a standard titanium alloy VT20L. Polythermal and isothermal sections of the phase diagram are plotted, the solidus and liquidus temperatures and the temperature of transition to the β-range under heating (Tpt) are determined. The methods of light and scanning electron microscopy are used to study the effect of heat treatment on the structure of alloy VT20L.



Magnesium Alloys
Effect of Plastic Deformation on the Structure and Properties of Alloy IMV7-1 of the Mg – Y – Gd – Zr System
Abstract
The microstructure and strength properties of hot-pressed alloy IMV7-1 of the Mg – Y – Gd – Zr system are studied after additional cold and hot rolling deformation. It is shown that the strength properties of the pressed alloy can be elevated by cold deformation at an admissible level of ductility.



Cast Irons
Effect of Admixtures of Surface-Active Elements in Fe – C – Si Alloys Under Rapid Solidification of Melt on the Quality of Structural Articles
Abstract
Computer and experimental studies of the effect of admixtures of Te and H2 surface-active elements (s.a.e.) on the kinetics of nucleation of crystallization centers and phase growth under accelerated crystallization of eutectic cast iron are performed. It is shown that under quenching cooling with decelerated diffusion processes the admixtures of s.a.e. in the melt play the role of initiators of diffusion redistribution of elements in formation and growth of new phase fragments affecting the structure and properties of the formed material.



Composite Materials
Possibilities of Scanning and Transmission Electron Microscopy for Comparative Analysis of the Microstructure of In-Situ Nanocomposite High-Strength Conductors Based on a Copper Matrix and BCC-Metals
Abstract
A method of preparation of samples and quantitative analysis of the structure of in-situ nanocomposite conductors is developed. The microstructure of specimens of in-situ nanocomposites of the Cu – Fe and Cu – V systems with diameter 0.44 – 0.80 mm is analyzed by the methods of transmission and scanning electron microscopyΩ. Both specimens are shown to have a grain-subgrain structure with grain size about 200 nm and precipitates of second phase (Fe/V fibers) with a length of 100 – 400 nm and a thickness of 10 – 80 nm (in cross section).



Heat Treatment
Effect of Annealing on the Microstructure of Rapidly Solidified Foils of Alloy Bi50Sn35In15
Abstract
The effect of annealing on the microstructure of foils of alloy Bi50Sn35In15 is studied. It is shown that prolongation of the annealing time is accompanied by coarsening of the structure, which reduces the specific surface of the interfaces virtually without changing the volume fractions of the phases.



Surface Engineering
Tribotechnical and Energy Assessment of Parts of Working Members of Cultivating Machines After Carburizing and Laser Hardening
Abstract
Results of experimental studies of low-carbon steel 20 and high-carbon steels of types 70 and 65G after carburizing, heat treatment and laser hardening are presented. The variation of the microhardness of the surface layers of the steels and of their wear resistance due to different variants of hardening is determined. Optimum modes of treatment aimed at raising the strength and wear resistance are suggested for the steels used for working members of cultivating machines.



Simulation
Simulation of the Elastoplastic Behavior of Grade-4 Ti in the ECAP-C Process
Abstract
Amodel of the elastoplastic behavior of commercial titanium is developed with allowance for the evolution of the microstructure of Ti Grade-4 Ti under equal channel angular pressing with application of the Conform process. The evolution of the mean dislocation density, of the dislocation density in the body and on the boundaries of grains, and of the density of mobile dislocations is studied. The concentrations of strain-induced vacancies, the speeds of gliding dislocations, and the angles of off-orientation between neighbor grains are determined, which widens substantially the understanding of the mechanisms of the elastoplastic behavior of Ti Grade-4 under severe plastic deformation.


