


卷 59, 编号 7-8 (2017)
- 年: 2017
- 文章: 25
- URL: https://journal-vniispk.ru/0026-0673/issue/view/14656
Transformations
Effect of Microalloying of Roll Steel 70Kh3G2VTB on the Kinetics of Phase Transformations and Fine Structure Under Crystallization and Heat Hardening
摘要
Decomposition of supercooled austenite in steel 70Kh3G2VTB under continuous cooling is investigated. The thermokinetic diagram of decomposition of austenite in the pilot steel is plotted. The temperature-time ranges of the structural transformations are obtained. The effect of the parameters of austenitizing on the processes of dissolution of the carbide phase under heating is described. The fine structure of the pilot steel is studied in different stages of heat hardening.



Inverse Martensitic α → γ Transformation in Nanostructured Maraging Steels
摘要
The critical temperature (As) of the start of heating-induced α → γ phase transformation has been determined in two nanostructured maraging steels. It is established that, irrespective of the method of nanostructure formation and dimensions of structure constituents within the range studied, the As value of the inverse martensitic transformation decreases so as to fall in the interval of aging temperatures. Special features of the development of α → γ phase transformation in the hardened matrix are determined. Factors favoring the decrease in As are analyzed and the results of investigations are generalized.



Article
Effect of Thermocycling on the Structure of Martensite and Kinetics of Martensitic Transformation in Alloy Fe – 30% Ni – 3% Pd
摘要
The methods of scanning electron microscopy, differential scanning calorimetry and x-ray diffraction are used to study the morphological and thermal characteristics of cooling-induced martensite in alloy Fe – 30% Ni – 3% Pd. It is shown that the kinetics of the martensitic transformation is athermal and the morphology is lamellar. The mean values of the parameters of the austenite and martensite lattices are 0.35704 and 0.28614 nm respectively. The thermocycling leaves the points As and Af invariable.



Inheritance of the Elastic Field of Martensite Nucleation Center by the Control Wave Process Initiating Deformations of Planes {110}c of Cubic Crystals
摘要
The possibility of inheritance of the elastic field in the zone of appearance of the initial excited state by the wave process controlling growth of the martensite crystal is shown. The case when the wave vectors of the control waves belong to plane {110}c of the original cubic phase is analyzed. Implementability of such inheritance is demonstrated with the use of elastic moduli for single-crystal bcc titanium, which advances the predictive capacity of the dynamic theory.



Effect of Neodymium and Zirconium on the Structure of Castable Magnesium Alloy ML10 (NZ30K)
摘要
Alloys of the Mg – Zn – Zr – Nd system with composition matching that of ML10 (NZ30K) and different contents of the main alloying components within the standardized range are studied. Four-component Mg – Zn –Zr – Nd phase diagrams are simulated, and the stages of crystallization of the alloys are considered. The structure of the alloys is determined in cast condition and after a T6 heat treatment. Fracture surfaces are analyzed. The distribution of the alloying elements in the structure is studied. The changes in the content of zirconium within the standardized range are shown to affect the grain size in the cast and heat treated states.



Effect of Extrusion-Sheer on the Microstructure and Mechanical Properties of Magnesium Alloy AZ31
摘要
The effect of extrusion combined with shear (ES) on the microstructure and mechanical properties of magnesium alloy AZ31 is studied. The additional die providing shear deformation of the extruded bars (two successive turns of the calibrating channel to equal opposite angles) provides refinement of grains. Growth of the deformation temperature causes grain growth. The intensity of the x-ray reflection from basal plane (0002) after the ES increases. After the deformation at 420°C fracture mainly develops by the transgrain mechanism. After the deformation at 450°C the maximum hardness corresponds to the largest grain size in the central part of the bar, and the fracture is chiefly determined by twinning.



Relaxation Resistance of Spring Strips from Austenitic-Ferritic Steel 03Kh13N10K5M2Yu2T
摘要
The mechanical and relaxation properties of corrosion-resistant aluminum-containing austenitic-ferritic steel 03Kh13N10K5M2Yu2T are considered as a function of the mode of preliminary thermoplastic treatment and its temperature-time conditions.



Effect of Low-Cycle Thermocycling Treatment on Corrosion and Mechanical Properties of Corrosion-Resistant Steel 12Kh18N10T Irradiated with Neutrons
摘要
The effect of thermocycling treatment on the susceptibility to local corrosion and mechanical characteristics of corrosion-resistant steel 12Kh18N10T in different states (after austenitizing, cold rolling, and neutron irradiation) is considered. The possibility of partial recovery of the corrosion and mechanical characteristics of irradiated reactor steel due to low-cycle thermocycling in a temperature range exceeding the irradiation temperature is demonstrated.



Fabrication of Intermetallic Titanium Alloy Based on Ti2AlNb by Rapid Quenching of Melt
摘要
The possibility of fabrication of rapidly quenched fibers from alloy Ti – 22Al – 27Nb by extracting a hanging melt drop is studied. The special features of the production of electrodes for spraying the fibers by sintering mechanically alloyed powdered components of the alloy, i.e., titanium hydride, niobium, and aluminum dust, are studied. The rapidly quenched fibers with homogeneous phase composition and fine-grained structure produced from alloy Ti – 22Al – 27Nb are suitable for manufacturing compact semiproducts by hot pressing.



Martensitic Transformation in Low-Carbon Steels
摘要
Isothermal and thermokinetic martensitic transformations in low-carbon martensitic steels have been studied. Amodel is proposed that relates the mechanical state of the austenite, as dependent on the parameters of thermal treatment and the law of the grain size distribution, to the volume fraction of transformed martensite. Physical constants of the transformation are determined.



Transformations of Supercooled Austenite in a Promising High-Strength Steel Grade Under Continuous Cooling Conditions
摘要
Special features of the transformations of supercooled austenite occurring under continuous cooling of a promising high-strength steel grade not standardized in the Russian Federation are determined. A method for evaluating the volume fractions of structure constituents formed in the steel as a result of cooling from 925°C at various constant rates within 0.025 – 75 K/sec is proposed and tested. The results are generalized in the form of a thermokinetic diagram of transformations of supercooled austenite.



Crack Resistance of an Alloy of the Al – Cu – Mg – Ag System
摘要
Cyclic crack resistance of an aluminum alloy of the Al – Cu – Mg – Ag system with a high content of doping elements is studied. It is shown that the alloy possesses a high threshold value of the stress intensity factor for nucleation of fatigue cracks. However, the nonuniform distribution of second-phase particles in the material reduces the crack resistance. Special features and main differences of the relief of fatigue fracture surfaces of the alloy in various regions of the kinetic diagram are considered. Coefficients of the Paris’ equation for the region of linear fatigue-crack growth are determined.



Softening and Hardening of Alloys of the Al – Zn System Under Plastic Deformation
摘要
The proportion of hardening and softening under plastic deformation at room temperature in metals and alloys of the Al – Zn system has been studied as dependent on the regime of preliminary heat treatment. The influence of the strain rate on the dependence of alloy hardness on the degree of plastic deformation is estimated.



Effect of Zircon Particle Size on Age Hardening Behavior of A356 Alloy Based Composites
摘要
Melt stirring was used to introduce various amounts of zircon (ZrSiO4) particles of various sizes into aluminum alloy A356 of the Al – Si system. The effect of zircon particle sizes on age hardening behavior of stir-cast A356 alloy/zircon reinforced composites was studied by measuring microhardness after solution treatment and aging for various times. The structure of composites was studied by methods of optical microscopy, x-ray diffraction, scanning electron microscopy combined with energy dispersive x-ray spectroscopy, and high-resolution transmission electron microscopy. The addition of zircon was found to accelerate age hardening of the matrix alloy. It is established that the maximum hardness increases and the time of attaining this maximum decreases with growing content of zircon particles and with reduction in their average size.



Special Features of the Structure of Laser-Welded Joints of Dissimilar Alloys Based on Titanium and Aluminum
摘要
The structure of laser-welded joints of parts having different thicknesses fabricated from alloys based on aluminum and titanium has been studied. Results of transmission and scanning electron microscopy measurements and x-ray diffraction analysis show that the diffusion interaction of microvolumes of two alloys in the weld leads to the formation of two interlayers: (i) a continuous intermetallic TiAl layer with thickness below 1 μm adjacent to the titanium alloy and (ii) a layer consisting of TiAl3 intermetallic dendrites with thickness of 2 – 6 μm adjacent to the TiAl layer. The average microhardness of the intermetallic layer is about 490 HV.



Mechanical Properties of Steel P92 Welded Joints Obtained By TIG Technology
摘要
Mechanical properties of P92 steel welded joints obtained using the TIG (141) technology have been studied upon post-welding heat treatment (PWHT). The microhardness, tensile strength, and impact toughness of metal in the weld and heat-affected zone are determined. The PWHT is shown to be obligatory.



Magnesium Alloys
Effect of REE on the Phase Composition and Properties of a New Refractory Magnesium Alloy of the Mg – Zn – Zr – REE System
摘要
A novel high-strength refractory alloy VMD16 of the Mg – Zn – Zr – REE system is described. The advantages of the alloy with respect to the counterparts are considered. The processes of formation of phase composition and of structural evolution are studied. A fine dispersed subgrain structure is shown to exist in the deformable magnesium alloy. The combination of the specific morphology and topology of the intermetallic phases with their thermal stability provides a high level of strength properties at room and elevated (300 – 350°C) temperatures at a low anisotropy.



Corrosion-Resistant Steels
Effect of Thermal Fields on the Structure of Corrosion-Resistant Steels Under Different Modes of Laser Treatment
摘要
The influence of temperature fields on the structure and properties of corrosion-resistant chromium steels under different modes of laser treatment is investigated. A model of heat transfer under laser impact on target is used to plot thermal fields and cycles and cooling rates. It is shown that the model used for computing thermal fields gives tentative geometric sizes of the fusion zones under laser treatment and selective laser fusion. The cooling rate is shown to have decisive influence on the structure of corrosion-resistant steels after laser treatment with surface fusion in devices for pulsed, continuous, and selective laser melting.



Aluminum and Titanium Alloys
Mechanical and Life Properties of Sheets from Alloys of the Al – Mg – Sc System
摘要
The characteristics of strength, static crack resistance, rate of growth of fatigue cracks and cyclic endurance of annealed sheets from weldable alloys of the Al – Mg – Sc system are studied as compared to annealed sheets from alloy AMg6. The compositions of aluminum alloys with scandium (01545 and 1570S) with characteristics substantially superior to those of AMg6 and level of properties comparable to that of the base aircraft not weldable alloy 1163 in state T6 are determined.



Technical Information
Effect of the Fractional Composition of Filler Powder and Parameters of Laser Coaxial Surfacing on Formation of Beads
摘要
An experimental study of the morphology of particles of a filler powder and of the characteristics of beads produced by laser gas-powder surfacing is performed. The main laws of formation of bead in the course of laser surfacing are determined. The optimum modes of deposition onto a substrate from steel 09G2S are suggested.



Aluminum Alloys
Effect of Homogenizing Heat Treatment of Liquid Aluminum–Copper Alloys on the Structure of Rapidly Crystallized Specimens
摘要
Centrifugal casting into a massive slot chill mold was used to prepare two series of specimens of alloys of the Al – Cu system, containing from 10 to 32.2 at.% Cu. The first series was fabricated without a homogenizing heat treatment of the melt, while the second series was fabricated with heating of the melt to 1400°C. Both kinds of specimens were cast at the same temperature in order to provide for the same cooling rate of about 104 K/sec. The structures, phase compositions and microhardnesses of the structural components are compared. It is established that the homogenizing heat treatment changes the kinetics of crystallization and, hence, the proportion of phases in the alloy structure and the copper content in them.



Refractory and Magnesium Alloys
Formation of the Structure of a Eutectic Alloy of the Nb – Si System During Directed Crystallization with Liquid-Metal Coolant
摘要
Peculiarities of the structure of a refractory eutectic alloy of the Nb – Si system, formed by the method of directed crystallization with liquid-metal coolant, have been studied. Characteristic zones of microstructure of the ingot obtained upon directed crystallization are considered, the alloy composition is analyzed, and volume fractions of phases in the Nb – Si composite are determined.



Formation of High-Coercivity State in Fe2NiAl Alloy During Decomposition of Solid Solution Under Quenching from Liquid State and Subsequent Annealing
摘要
The methods of transmission electron microscopy, atomic force microscopy, x-ray diffraction, and magnetic measurements were used to study the laws of formation of the microstructure and magnetic properties in Fe2NiAl (alni) alloy after quenching from liquid state and subsequent annealing at 500 – 780°C. The microstructure of rapidly hardened flakes is characterized by the presence of inhomogeneities less than 10 nm in size and boundaries of anti-phase domains. Annealing of the flakes is accompanied by their discontinuous decomposition, which causes growth of the colonies comprising alternating plates of β′ and\( {\upbeta}_2^{\prime } \) phases on grain boundaries.



Thermochemical Treatment
The Influence of High-Pressure Gas Nitriding on the Properties of Martensitic Steels
摘要
The influence of high-pressure gas nitriding on the structure and properties of martensitic steels VKS-5, VKS-7, 20Kh3N3MFB, and 25Kh5M is investigated. It is shown that the high-pressure nitriding increases the thickness of the diffusion zone at substantial reduction of the process time as compared to the traditional gas-phase nitriding. Increase of the post-treatment cooling rate above 30 K/min favors the formation of diffusion layers with greater hardness.



Welded Joints
A Study of the Structure of Steel – Titanium Joints Formed by Diffusion Welding with the Use of Ultrafine Nickel Powder
摘要
The structure and phase composition of welded joints of austenitic steel 08Kh17N10T and titanium alloy PT-3V formed by diffusion welding with an intermediate layer of ultrafine nickel powder have been studied. The microstructure of joints welded in various regimes was studied using metallographic and energy-dispersive x-ray microanalysis techniques. Good prospects of the application of ultrafine dispersed media for diffusion welding of steels and titanium alloys are shown.


