D16 Aluminum Alloy Research Articles

Structure of the aluminum alloy Al-Cu-Mg cryorolled to different strains

Methods of optical metallography, X-ray diffraction, and transmission and scanning electron microscopy were used to study changes in the structure of the aluminum alloy D16 (2024) caused by isothermal rolling at a temperature of liquid nitrogen. It has been established that the basic structural changes that take place in the material upon deformations to e ∼ 2.0 are due to the formation and evolution of the dislocation structure, which contains cells of nanometer size. With further straining to e ∼ 3.5, the processes of recovery and recrystallization become activated, which lead to the formation of a mixed grain-subgrain nanosized structure.

New Technologies of Anodizing Components of Oil and Gas Industry Equipment Made of Aluminum Alloys

The injection of ozone into the air mixture for a barbotage of electrolyte at anodization of an aluminum alloy D16 in 5 % aqueous solution of sulfuric acid increases final thickness of oxide coating by 45 - 53 %, and simultaneous ultrasonic affecting and bubbling of electrolyte by the ozone-aerial mixture - only on 30 - 35 %, however in the latter case microhardness and wear resistance of coating increase. The additional applying of vibration decreases thickness, microhardness and wear resistance of an oxide layer.

Preparation of Aluminum Oxide Ceramic Precursors by Dispersion of Aluminum Alloy D16

A chemical method with reaction of aluminum alloy D16 and aqueous sodium hydroxide solution is used to prepare very fine aluminum hydroxide powder. It is established by x-ray phase analysis that the powder obtained consists of three aluminum oxide modifications: gibbsite, boehmite, and bayerite. It is shown by laser diffraction that within an aluminum oxide suspension there is extensive bimodal distribution of particle size distribution (0.4 – 190 μm). The powder obtained is a precursor for preparing aluminum oxide ceramic.

Acoustic Emission at the Kinetic and Development of the Structural Defects under Deformation of Aluminum Alloy

The paper presents the results of studies the deformation behavior of aluminium alloy D16 by acoustic emission (AE) method. The purpose of this study was to establish the deformation stages and deformation mechanisms at each stage. Studies were carried out on the samples of aluminum alloy D16 (analog 7075). This paper contains a method for the separation of AE signals. The method of AE sources identification based on the the two-parameter distribution analysis (frequency parameter Kfvs energy of AE signals). The frequency parameter Kf is based on wavelet transform of AE signals. Two-parameter distribution allows one to separate the AE signals emitted by dislocations from the signals of micro cracks. The investigation results allowed the various deformation stages to establish by the different types of AE signals. By the AE analysis shows the dislocation mechanism of hardening the aluminum alloyD16. The paper presents the results that characterize the influences of heat treatment and structural condition of aluminum alloy on the AE parameters.

Effect of radial-shear rolling on structure of aluminum alloy D16 (Al-4.4Cu-1.6Mg)

The modes of radial-shear rolling (RSR) of hot-pressed rods of aluminum alloy D16 providing for production of high-quality long-length semifinished items are experimentally studied. Investigations of the microstructure of alloy D16 reveal that the rolling modes provide its homogeneous refinement. The average distance between high-angle grain boundaries in longitudinal cross section decreases from 10 to 6.5 μm, whereas the average size of subgrains in the surface layer and central part amounts to 0.9 μm.

Diagnosis of Metal Plates with Defects Using Laser Vibrometer

The method of nonlinear laser scanning vibrometry is used for diagnostics of thin cylindrical resonators of polycrystalline aluminum alloy D16 with latent defects and residual stresses. Flexural Lamb waves are used for diagnosis. The dependence of the frequency of the resonator eigenmode on the amplitude of the flexural Lamb waves in it is detected (the effect of the fast dynamics); it indicates the presence of defects in the material of the resonator. Coordinates of defects were identified by vibromodulation technique in the resonator.

Low-Temperature and Corrosion Fatigue Crack-Growth Resistance of D16ATNV and V95T1 Aluminum Alloys after Long-Term Operation

The cyclic crack resistance of D16ATNV (2024-T3 type) and V95T1 (7075-T6 type) degraded aluminum alloys is investigated. The specimens are cut out from different zones of the wing skin of an AN-12 aircraft after 40 yr of its operation along (L-specimens) and across (T-specimens) the direction of rolling of skin sheets. The tests were carried in air at temperatures of 20 and – 60°C and in a corrosive medium (3.5% NaCl solution). It is shown that the effects of low temperature and corrosive medium on the fatigue threshold ΔK th and cyclic fracture toughness ΔK fc for D16ATNV alloy are qualitatively similar to the effects observed for D16 and V95 aluminum alloys in the as-received state. At the same time, the indicated effects are absolutely different for V95T1 alloy.

Metallic layered composite materials produced by explosion welding: Structure, properties, and structure of the transition zone

The structure, morphology, and microhardness of the transition zone in multilayer metallic composite joints are studied, and the cohesion strength of the plates to be joined, the mechanical properties of the formed composite materials, and fracture surfaces are analyzed. The materials to be joined are plates (0.1–1 mm thick) made of D16 aluminum alloy, high-strength maraging ZI90-VI (03Kh12N9K4M2YuT) steel, BrB2 beryllium bronze, and OT4-1 titanium alloy. Composite materials made of different materials are shown to be produced by explosion welding. The dependence of the interface shape (smooth or wavelike) on the physicomechanical properties of the materials to be joined is found. The formation of a wavelike interface is shown to result in the formation of intense-mixing regions in transition zones. Possible mechanisms of layer adhesion are discussed.

Multi-scale model of steady-wave shock in medium with relaxation

The propagation of a steady wavefront in a medium with three levels of plastic deformation is considered: (a) dislocation, (b) meso-scale and (c) macro-scale. To take into account collective mechanisms of microplasticity, a relaxation term describing the momentum exchange between meso- and macro scales is incorporated into a dislocation-based constitutive law. This leads to a nonlinear second-order differential equation. Analytical and numerical analyses of the equation are performed. Using as example D16 aluminum alloy, we determine the parameters that provide a satisfactory correspondence between calculated and experimental profiles of particle velocity.

Oxide coatings modified with transition and rare-earth metals on aluminum and their activity in CO oxidation

Oxide catalysts, which, in addition to Al2O3 + SiO2, contain from one (Ni) to four oxides or compounds of transition metals (Ni, Cu, Mn, and Co) and oxides or compounds of rare-earth elements (Ce, La), are produced on D16 aluminum alloy by plasma electrolytic oxidation combined with impregnation and subsequent annealing. The composites formed begin to catalyze the CO oxidation in a temperature range of from 100 to 300°C. The catalysts used can be arranged in the following series of decreasing catalytic activity: Ni-Cu-Mn-Co-Ce > Ni-Cu-Mn-Co-Ce-La ≈ Ni-Cu-Mn-Co > Ni-Cu-Mn > Ni-Cu > Ni. Oxygen compounds of Cu+, Cu2+, Mn4+, Co3+, Ce3+, and Ce4+, which seem to determine the catalytic properties of the oxide systems studied, are found on the surface and in the subsurface layer with a total thickness of ∼6 nm of the most active Ni-Cu-Mn-Co-Ce catalyst.

Obtaining composite oxidic coatings on the surface of aluminum and alloys thereof

We have obtained and investigated manganese-containing oxide-ceramic coatings on the surface of D16 aluminum alloy. It is shown that such coatings are promising as electrode materials in electrolytic systems and when the protective properties of the substrate are enhanced.

Експериментальне визначення ефекту Баушингера і пошкоджуваності матеріалу

Present paper is devoted to an experimental determination of the Bauschinger effect and material damage which occur at elastic-plastic deformation. The series of cyclic tension-compression tests of flat samples made from aluminum alloy D16 were conducted. Given a phenomenon of buckling at compres-sion stage the flat samples were cut according to both ATSM standard and preliminarily conduction of the buckling analysis. Based on the experimental data a mathematical model of plasticity is developed in the way of improvement of the nonlinear kinematic hardening model by introducing of an additional function of previously accumulated plastic strain. For better correlation with experimental results the Mises plasticity criterion written in the form of the Baltov and Sawczuk’s model was modified by intro-ducing of a function which is intended to describe decrease of the yield stress during plastic deforma-tion. In order to model a reduction of the young’s module at unloading stage of the cyclic tension-compression test a material damage parameter was introduced according to the effective stress concep-tion. Numerical simulation of the cyclic tension-compression testing which accompanied experimental investigation has shown good coincidence with experiment results.

An Analytical Model for Fatigue Crack Propagation Prediction with Overload Effect

In this paper a theoretical model was developed to predict the fatigue crack growth behavior under the constant amplitude loading with single overload. In the proposed model, crack growth retardation was accounted for by using crack closure and plastic zone. The virtual crack annealing model modified by Bauschinger effect was used to calculate the crack closure level in the outside of retardation effect region. And the Dugdale plastic zone model was employed to estimate the size of retardation effect region. A sophisticated equation was developed to calculate the crack closure variation during the retardation area. Model validation was performed in D16 aluminum alloy and 350WT steel specimens subjected to constant amplitude load with single or multiple overloads. The predictions of the proposed model were contrasted with experimental data, and fairly good agreements were observed.

Specifics Deformation Aluminium Alloy D16 in Conditions Additional Load Impulse

The technique of recording the changes in the dynamic deformation field of non-equilibrium processes in the alloys of aluminum. It was established experimentally that the structural changes are implemented in the propagation of elastic waves in the material deformation. Qualitatively be characterized distribution of high plasticity surface of the specimen and determined its size after realization of dynamic non-equilibrium processes.

Structural Stability and Variation of Properties of Aluminum Alloys D16 and 1953 in Production and Operation of Drill Pipes

The effect of the temperature and time parameters of production and service of drill pipes from aluminum alloys D16T and 1953T1 on their structure and mechanical properties is studied. The structural changes in the alloys due to production and operation heatings are determined.

Formation of micro-arc coatings on the surface of D16 aluminum alloy

Results of a study of how optically black coatings are formed by micro-arc oxidation on the surface of D16 aluminum alloy are reported. Coatings with high optical properties were obtained on this alloy in the pulsed anodic-cathodic mode of treatment in the electrolyte composition developed in the study.

Investigation of deformation and fracture by acoustic emission data, correlation of digital images, and strain measurements

To analyze the deformation of solid bodies, it was proposed to use simultaneously three in situ methods of data registration, including loading diagram (macroscale level), correlation of digital images (mesoscale level), and acoustic emission (microscale level). The complex for multiscale in situ investigation of deformation and fracture processes, the operating principle of which is based on interconnection of duration of the characteristic stages of change in the informative parameters and their ratios with the leading scale level, was implemented. By the example of stretching of the samples of aluminum alloy D16 with cut of different depth, the characteristic stages of change in the derivative of the load applied, AE activity, and intensity of shear deformation on the degree of deformation were revealed. It was shown that the characteristic stages marked on graphs of changes in all informative parameters on time agree well between each other and refer to elastic deformation, parabolic strengthening, and crack propagation.

Межкристаллитная коррозия алюминиевого сплава Д16 после криопрокатки и старения

The effects of cryorolling with a strain of e~2 at liquid nitrogen temperature and further natural and/or artificial aging on the resistance to intergranular corrosion (IGC) of preliminary quenched D16 aluminum alloy have been investigated. It is shown that cryorolling increases IGC depth and intensity for both T4 and T6 conventionally aged alloy conditions. Structure and phase factors of the alloy IGC after processing with and without cryodeformation are discussed in detail.

Impact failure of metallic rings by a magnetic pulse technique

Metallic rings made of D16 aluminum alloy are studied upon the application of a distributed radial load by a magnetic pulse technique. Two approaches making it possible to decrease the period of the sin-wave load by seven and fifty times are developed. In addition, they allow one to determine the instant of rupture of the ring from a flash arising at rupture with the help of a photodetector. Simultaneously, the load pulse and a signal from the photodetector are displayed with a digital oscilloscope. It is shown that, when the load pulse shortens, the ductile component of fracture declines and the samples fail in a more brittle manner.

Hydrogen redistribution in aluminum alloy D16 and AK4-1 rods induced by internal stresses

Near-surface hydrogen segregation with a concentration that is at least three times higher than that in the internal layers is detected in D16 and AK4-1 alloy rods subjected to standard hardening heat treatment. When AK4-1 alloy rods are stored, hydrogen from the segregation region propagates into the metal volume via two dissolved hydrogen waves moving toward the volume and surface of a rod rather than via a classic diffusion way. The segregation region with an initially high hydrogen content eventually becomes almost free of hydrogen. Both the directions and anomalously high velocities of low-temperature uphill (against the concentration gradient) hydrogen flows in the rods are explained by the effect of internal stresses in the alloys.