D16 Aluminum Alloy Research Articles

Системный подход к проблеме поверхностного упрочения алюминиевых сплавов лазерной обработкой

The paper studies the matter of theoretical regularities of reactant transport mechanisms in laser surface alloyage of aluminum alloys. It is shown that, along with the traditional diffusion saturation a convective mechanism of reactant transport and the process of refractory particles introduction play a significant role for alloying components flow entering a molten pool in the alloyed zone. An increase in wear resistance was found if alloying aluminum alloy D16 with chromium, nickel and niobium disilicide.

Superhydrophobic coatings of phosphonic acids, formed on surface of D16 aluminum alloy for its protection against atmospheric corrosion

Новые технологии, Химическая промышленность, Химическая технология, Научные журналы, Защита от коррозии, Технология металлов, Свойства материалов, Технические журналы, Наука и технологии, Справочная литература, Научные разработки

Development and experimental testing of the technology for producing deformed bars of D16(T) alloy from continuously cast billets of small diameter with low elongation ratios

The article describes the development and pilot-scale testing of the technology for producing bars of the D16(T) aluminum alloy by radial-shear rolling from continuously cast billets with a diameter of 72 mm in several passes. The actual dimensions of rolled bars were within the ±0.16 mm tolerance for all bar diameters, which significantly surpasses the GOST 21488-97 requirements. According to the results of tensile tests, the values of ultimate strength, conventional yield strength, relative elongation and relative reduction were determined. Ultimate strength and relative elongation requirements specified by regulatory documents for the D16(T) alloy were met with a total elongation ratio of more than 4.2. In terms of plastic properties, the obtained bars surpass the GOST requirements by 2.1–2.5 times in the entire range of elongation ratios investigated starting from 2.07. At the same time, there is an increase in the relative elongation by 5.7–6.8 times in comparison with the initial cast state. The microstructure and morphology analysis conducted for secondary phases showed that with a decrease in the bar diameter (with an increase in the total elongation ratio), the average particle size of the α(AlFeMnSi) phase insoluble in the aluminum matrix decreases, which is a consequence of deformation processes developed during rolling. Additional grinding of inclusions during deformation processing can significantly reduce the possible negative effect of the insoluble phase on the mechanical properties of resulting bars, in particular on the plasticity properties. The microstructure analysis showed that bars after rolling and heat treatment are free from cracks, looseness, delamination, and other defects and meet the requirements of GOST 21488-97.

Improvement of the comprehensive automation control system for dynamic processes of hot deformation processing on thermoelastic presses

The researches results of the automated control system improvement for a thermoelastic press in the implementation of the processes of isothermal deformation and metallic materials stamping in a state of superplasticity are considered. It is established that the deviation from the optimal temperature-speed deformation regimes leads to the defect formation in the article body in the form of sinks, clamps, oxide films drawn into the article from the surface of the semi-finished product. These defects are stress concentrators that can lead to the destruction of loaded parts. The main problem that prevents the active industrial use of automated control systems for considered equipment is determined — their inertia. Measures to eliminate the inertia of the automated control system for thermocompression plants are proposed. It is shown that the main and most effective method for solving this problem is the use of digital extropolation algorithms for short-term prediction of the measuring and control system behavior. The improved automated control system has been successfully tested at stamping of finned aircraft panels and shells made from aluminum alloys D16, V95, V96ts, 01420. The system provided control of the temperature and speed parameters for metal materials stamping in the state of superplasticity and under isothermal stamping conditions with a heating accuracy of 2... 4 °С and the accuracy of the speed parameter compliance (deformation rate) up to 0.1 mm/s. Keywords isothermal forging, thermal compression, thermal expansion, defects, automated control system, system inertia

Study of microarc oxidation coatings friction and wearing under base oils greasing conditions

The presented paper is considered the issues of coatings wear resistance formed by the microarc oxidation method (MAO-coatings) on aluminum alloys. To form coatings, the aluminum alloys D16 (2024) and V95 (7075) in base weakly alkaline electrolyte and its modification by the way introduction into it such components like sodium aluminate, suspension of fluoroplastic and their combination with carbon nanoparticles were used. Tribotests of the friction couple "MAO-coating — steel ShKh15" by the scheme "Ring—Ring" under greasing condition performed an improvement of MAO-coatings tribological characteristics in the electrolyte modified by the fluoroplastic suspension.

Исследование формирования многослойного функционального композиционного материала с градиентной структурой “нитрид титана – титан – основа”

Composite materials based on aluminum alloy D16 and titanium alloy Ti – 10 Nb – 3 Mo with surface layers of titanium, titanium nitride and a multilayer composition consisting of alternating layers of titanium and titanium nitride for biomedical and tribological purposes by high-vacuum magnetron sputtering at direct current in inert and reactive media were obtained. The structure and phase composition were studied using SEM, AES, X-ray diffractometry and probe microscopy. The rate of formation of a surface layer of pure titanium on a substrate made of alloy D16 was 185 nm/min, and the rate of synthesis of a surface layer of titanium in a reactive medium was significantly slowed down and was no more than 70 nm/min due to nitrogen poisoning of the target. The transition layer formed as a result of the synthesis of a titanium layer on an aluminum alloy substrate had a thickness of about 600 nm, which is significantly greater than the thickness of the transition layer when titanium is obtained on a titanium alloy substrate. During the formation of titanium nitride on a titanium sublayer, a greater concentration of nitrogen was observed than during the formation of nitride on a substrate with the same deposition parameters. The intensity of the TiN phase reflexes in the X-ray diffractometry diagrams were weakly expressed in all variants of the applied ratios of working gases Ar/N2 during spraying. The speed of the titanium sublayer makes it possible to form a greater thickness of the titanium nitride layer than without the sublayer, as well as a more nitrogen–saturated surface layer - up to 38% by weight.

Influence of fast dynamics effects on resonant ultrasonic vibrations of polycrystalline metal rods

A theoretical model for the formation of ultrasonic signals in metallic microcrystalline rods taking into account the metastable behavior of their defective states is proposed. The influence of metastable states of the defective structure of samples on the features of changes in their resonant frequencies in ultrasonic experiments of fast dynamics is analyzed. The decrease in Young's modulus in such processes is explained. The correspondence between theoretical and experimental data is demonstrated for the example of resonant acoustic vibrations of rods made of aluminum alloy D16. Keywords: nonlinear resonant ultrasonic spectroscopy, defect structure, mechanical stresses, effects of fast and slow dynamics.

Влияние эффектов быстрой динамики на резонансные ультразвуковые колебания стержней из поликристаллических металлов

A theoretical model for the formation of ultrasonic signals in metallic microcrystalline rods taking into account the metastable behavior of their defective states is proposed. The influence of metastable states of the defective structure of samples on the features of changes in their resonant frequencies in ultrasonic experiments of fast dynamics is analyzed. The decrease in Young's modulus in such processes is explained. The correspondence between theoretical and experimental data is demonstrated for the example of resonant acoustic vibrations of rods made of aluminum alloy D16.

Ускоренная оценка влияния технологических факторов на прочностные характеристики Ti-6Al-4V И Al-Cu-Mg

Introduction. The strength of construction materials when used under cyclic loads is of great importance in design engineering. A significant number of factors that affect the fatigue resistance have predetermined the creation of numerous methods that consider such influence. Nondestructive methods that are based on the connection of the physical degradation of material with strain properties enable evaluating experimentally the fatigue properties of materials. Purpose of study: the analysis of the processes of energy dissipation and strain accumulation during the inelastic cyclic strain of samples, using the VT6 (Ti-6Al-4V) titanium alloy and the D16 (Al-Cu-Mg) aluminum alloy before and after the technological impact. The work experimentally investigates the physical processes of degradation of the VT6 and D16 alloy samples that accompany the process of fatigue failure in materials with homogeneous and inhomogeneous stress-strain states in the concentrator (in the form of a hole and a weld). Typical modes are used to reach the fatigue testing that determine the critical stress in a material sample – the stress at which physical properties (temperature, strain) change without reaching the fatigue failure of samples. Critical stress amplitudes in the cycle, based on the data obtained during the experiment and the results of mathematical simulation, are compared. The effect of stress concentrators on critical loads that a detail can withstand after a unit operation is estimated by the finite-element method (FEM). As a result, the effect of the operational and technological factors on critical stress determined by strain and temperature is estimated. Comparative tests of the VT6 and D16 alloy samples with and without stress concentrators showed that the amplitudes of critical stress decrease by more than 30% in comparison with the ones that are without stress concentrators. The low-cycle fatigue tests of the D16 alloy samples are carried out. Mathematical simulation of the cyclic strain of the samples is carried out using MSC.Marc package. The results of the cyclic loading tests, which show that the characteristics of the technological process reduce the amplitudes of the critical stress of the VT6 and D16 alloys and affect the fatigue properties of the D16 aluminum alloy, are discussed. Mathematical simulation corresponded positively to the experimental data. Such correspondence indicates the possibility of conducting qualitative numerical assessments of the beginning of the inelastic strain accumulation process in structures with stress concentrators under the cyclic stress and the increasing stress amplitude, using the typical sample made of hardening elastoplastic material.

Influence of Radial-Shear Rolling Conditions on the Metal Consumption Rate and Properties of D16 Aluminum Alloy Rods

Influence of Radial-Shear Rolling Conditions on the Metal Consumption Rate and Properties of D16 Aluminum Alloy Rods

Антикоррозионные и гидрофобные свойства пленок карбоновых кислот на поверхности алюминиевого сплава Д16

The production possibility of protective films of higher carboxylic (lauric, stearic (SA), oleic and linolenic) acids on a laser-textured surface of an aluminum alloy D16 is discussed. It is shown that such a modification leads to superhydrophobization (SHP) of the alloy surface. The most optimal type of laser processing has been determined: laser power is 12 W and the pass speed is 1000 mm / s. Profilometric measurements determined the average size of surface irregularities which is 6,47 microns. The degradation results of the SHP state in an aqueous solution of 0,05 M NaCl indicate greater stability of films formed from SA solutions. The protective ability of the coatings was evaluated by polarization measurements and corrosion tests in a salt chamber. It was found that films formed from an SA solution had the best anticorrosive properties. According to polarization measurements, an increase in ΔEpt = 220 mV, and the time of the first corrosion damage appears τcor = 384 h.

Numerical and experimental verification of a method of identification of localized damages in a rod by natural frequencies of longitudinal vibration

A method for identification of multiple transverse cracks and other localized defects in a rod by means of two spectra of longitudinal vibrations that correspond to free–free and fixed–free end conditions is presented. A numerical algorithm is developed that implements the method. The algorithm was tested on experimental data obtained on a cylindrical sample of aluminum alloy D16 with the created localized damages. The experiments were carried out on a rod with free ends. The created damages were ring grooves symmetrically located relative to the middle of the rod. With the help of such experiments, natural frequencies were obtained that correspond to two types of boundary conditions for a half-length rod. The experimental data were processed using the developed algorithm. The results showed that the model on which the developed algorithm is based describes well the longitudinal vibrations of the rod with localized damages in a fairly wide frequency range, and the algorithm enables to reconstruct multiple damages accurately enough.

Modeling the Stress-Strain Curve of Elastic-Plastic Materials

The work is devoted to the formulation of mathematical models of plastic materials without hardening. A functional is proposed, the requirement of stationarity of which made it possible to formulate the differential equation of stress as a function of deformation. On the linear deformation section, a second-order functional is proposed; on the non-linear deformation section, a fourth-order functional is proposed. A range of boundary value problems is formulated, that ensure the continuity of the function at the boundary of the linear and non-linear sections of the deformation curve. The theoretical strain curve was compared with the samples of experimental points for materials: St3sp steel, steel 35, steel 20HGR, steel 08Kh18N10, titanium alloy VT6, aluminum alloy D16, steel 30KhGSN2A, steel 40Kh2N2MA, and showed a good agreement with the experiment. Thus, a variational model is constructed, that allows one to construct curve deformations of various physically non-linear materials, which will allow one to construct further mathematical models of the resource of such materials.

Strength analysis of composite plates with auxetic honeycomb at static bending by the finite element method

In this paper, three-layer composite plates with continuous outer layers and an auxetic honeycomb interlayer of the chiral type based on rotating circles with tangentially attached rods are modeled. The physical and mechanical properties of the D16 aluminum alloy were chosen as the material properties of the layers of the composite plates. In the course of modeling, the discretization and volume of honeycomb structures in composites were varied at a constant thickness of the layers. Under the conditions of static bending of composite plates, load values were determined, at which maximum stresses in composites were equated to the conditional yield strength. The problem was solved using the finite element method in the framework of the theory of elasticity. The aim of this work is to study the influence of the discretization parameter and volume of the auxetic honeycomb interlayer on the magnitudes of load at yield strength stresses for the proposed composite plates.

Performance of Protective Coatings for Aluminum Alloys in the Operating Conditions of Oil Production Equipment

The paper investigates wear resistance and corrosion resistance of protective coatings of D16 aluminum alloy under conditions that simulate operation of drill pipes. The paper also presents microstructure of coatings, electrochemical potential and corrosion rate of D16 aluminum alloy with various coatings. We evaluated adhesion and wear resistance of these coatings. D16 alloy with a tungsten carbide coating has the widest range of service properties and can be used to effectively protect the surface of aluminum drill pipes during operation operation.

Corrosion Protection of Aluminum Alloys AMg3 and D16 with Chromate-Free Conversion Coatings in a Tropical Marine Climate

Abstract—In this paper, chromate-free conversion coatings on aluminum alloys D16 and AMg3 are studied in a tropical marine climate. It has been shown that the conversion coating IFKhANAL-3 independently provides corrosion protection for aluminum alloy AMg3 for 9 months, and for alloy D16, for 6 months. Additional treatment with acrylate or PTFE varnishes makes it possible to increase this to 12 months or more.

Laser Alloying of the Surface Layers of Aluminum Alloys for Improving Their Wear Resistance

The possibility of increasing the wear resistance of components made from AL25 and D16 aluminum alloys via surface alloying of the functional surfaces of the components is considered theoretically and experimentally. The mass transfer within the surface laser alloying (SLA) zone is a complex process due to the following three simultaneously occurring phenomena: the diffusion, thermocapillary convection, and incorporation of coating particle conglomerates into the melt zone during the fast evaporation of their surface layers in the field of power laser radiation. Various experimental schemes are selected using a theoretical analysis. Qualitative, quantitative, and physical studies of the process are performed. Recommendations for the selection of laser treatment conditions are given. The role of the alloying powder particle size is analyzed.

Plasma Electrolytic Oxidation of Titanium Alloys To Protect Adjacent Aluminum Alloys Element from Contact Corrosion

The plasma electrolytic oxidation of the titanium alloy OT4 was studied; the characteristics of the resulting coatings were determined–thickness, breakdown potential, corrosion current density, and X-ray phase; micro-X-ray spectral analysis was performed, and the morphology of the coatings was studied by scanning electron microscopy. We studied the effect of plasma electrolytic oxidation of OT4 and additional treatment of PEO coatings on the corrosion resistance of the aluminum alloy D16 (An.Ox.nchr, anodic treatment in chromate solutions) in contact with the titanium alloy in structurally similar samples.

Protection of D16 Alloy against Corrosion in Neutral Aqueous Solutions and in an Aggressive Atmosphere Using Organic Inhibitors

The possibilities of protecting the aluminum alloy D16 with organic corrosion inhibitors are considered. The protective ability of the obtained nanoscale layers was evaluated by an express method (drop test), tests in a heat and moisture chamber, salt spraying, and electrochemical impedance spectroscopy. The efficiency of treating D16 in aqueous solutions of organic inhibitors is correlated with the protective ability of chromate films.

New atmospheric corrosion inhibitor of aluminum alloy D16

The application of mixed corrosion inhibitor (CI), which is an equimolar composition of oleoyl sarcosinate (SOS) and sodium flufenamate (SFF), for protection of D16 aluminum alloy from atmospheric corrosion has been studied. The polarization measurements used to assess the effectiveness of preliminary passivation of the alloy with solutions of SOS, SFF and their composition showed significant advantages of mixed CI. The XPS method was used to study features of CI adsorption on the surface of D16 alloy. It has been established that upon adsorption of SOS and SFF separately a monolayer is formed, firmly bonded to the alloy surface, thickness of which is not exceeding 2.6—3.2 nm. After the joint adsorption of these CI, the layer thickness reaches 12—20 nm. The composition of this layer includes a considerable amount of Al3+ ions (~20%) related to their compounds with SFF and SOS, as well as to aluminum hydroxides. A possible mechanism for the formation of such a protective layer is proposed. The results of corrosion tests in a humid atmosphere with daily water condensation on samples of D16 alloy confirmed the high protective ability of the mixed CI film.