All Russian Scientific Research Institute of Aviation Materials

Studies of structural and phase transformations in a cast structural alloy based on the Ni3Al compound depending on the alloying balance, heat treatment, use of a heat-resistant coating, and performance of high-temperature static tests are presented. It is shown that the intermetallic alloy VIN4M and the composite coating calculated taking into account the alloying balance retain thermal stability after heat treatment including hot isostatic pressing and after long-term static tests.

We have developed a specimen configuration with a tailored through-thickness residual stress distribution with the aim of working out conditions for assessing residual stresses by both mechanical and physical methods. The procedure for producing such a specimen is based on nonuniform plastic deformation of an aluminum beam with a rectangular cross section in pure bending. During the loading process, the deformed state was monitored on the end face of the specimen by measuring the normal strain field with a digital image correlation system. The depth of the plastically deformed layer was determined to be 1.3 mm. We obtained a stress state of opposite sign, symmetric with respect to the neutral axis. A theoretical distribution of residual stresses after unloading the plastically deformed specimen was evaluated by numerical finite element calculations with allowance for physicomechanical characteristics, elastoplastic hardening, and the stress–strain curve in true coordinates for uniaxial tension of elementary specimens. Residual stresses nonuniform in the thickness direction have been studied by the hole drilling method in accordance with the ASTM E837 standard on two opposite sides of the specimen: in the tension region during deformation and in the compression region. The strain response during drilling was monitored using three-axis strain gage rosettes. The measured longitudinal residual stress component was compared to its theoretical distribution obtained numerically. In particular, the root mean square error of residual stress measurements relative to the theoretical distribution for an aluminum alloy specimen has been shown to reach 18.7 MPa. It is worth noting that larger measurement errors were obtained at small depths, characterized by relatively low strain, comparable to shot noise.

This article presents the results of a study of the influence of cooling modes during quenching on the structure and corrosion resistance in NaCl aqueous solutions of a high-tech deformable corrosion-resistant alloy V-1341 in a state after artificial aging. The structure and corrosion resistance of this alloy in the annealed state were also studied. Studies were carried out using the potentiodynamic method, electrochemical impedance spectroscopy, and transmission electron microscopy. The results obtained can be used when choosing the quenching cooling modes for products made of alloy V-1341 and predicting their corrosion resistance.

The influence of the crystallographic texture and phase composition of 1441, V-1461, and V-1469 alloy sheets of the Al–Cu–Li system on the anisotropy of Young’s modulus is studied. The {110} $$\left\langle {112} \right\rangle $$ brass-type texture is shown to form in the sheets and to cause the same anisotropy of the elastic modulus of the alloys: the maximum value in the direction transverse to the rolling direction and the minimum value in the direction at an angle of 45°. This corresponds to the peculiarities of elastic anisotropy of aluminum. The quantitative ratios of the δ' (Al3Li) and T1 (Al2CuLi) phases are determined using a unique procedure of phase analysis, and their elastic moduli are estimated. Young’s modulus averaged over three chosen directions (along and across the rolling direction and at an angle of 45°) is found to be proportional to the total content of intermetallic compounds.

A method is proposed to determine uncontrolled areas of aircraft engine parts in penetrant testing, taking into account the specifics of applying developers of different types (all forms according to ISO 3452-3). The main technological factors affecting the testability of surfaces of parts of complex geometry are presented. A method has been experimentally tested, which makes it possible to determine the uncontrolled zones of engine parts in penetrant testing, due to the specifics of applying different forms of developers. It has been established that when carrying out penetrant testing of parts, especially with complex configurations/geometry, the existing technologies for applying developers may not ensure its high-quality application to all controlled surfaces of parts, as was previously assumed based on the results of an expert assessment. It has been experimentally proven that such structural elements of parts as holes are controlled to a depth much less than the diameter.

The microstructure, the microhardness of the near-surface layer, and the contact fatigue of austenitic–martensitic VNS9-Sh TRIP steel are studied after tribotechnical tests at loads corresponding to maximum normal stresses σZmax = 2500–4000 MPa. An increase n the stresses in the contact zone from 2500 to 4000 MPa is found to increase the thickness of the near-surface layer with a hardness more 290 HV, which underwent martensitic transformation. As the contact stresses in VNS9-Sh steel decrease from 4000 to 2500 MPa, the contact life of this steel increases by a factor of more than 63, and the surface endurance limit of the quenched VNS9-Sh steel with a hardness of 220 HV is 2300 MPa, which is higher than that of bearing 95Kh18-Sh steel with a hardness of 650 HV by 15%.

The possibility of estimating the defect sizes during the preparation of samples with artificial defects using eddy current testing is considered. The designs of orthogonal and absolute eddy current probes are compared, and it is recommended to use absolute eddy current probes for materials with a high electrical conductivity. An analysis of the obtained experimental results shows that the sensitivity and accuracy of the eddy current method can be significantly increased during static loading of samples (creation of tensile strains in the defect zone). This finding will allow us to prepare samples with defects the sizes of which are significantly smaller than those detected by standard control systems.

Combustibility requirements for aircraft materials are shown. Data are presented about the main methods of making adhesives less combustible by adding fire retardants, such as halogenous and phosphoric compounds, as well as mineral fillers that release carbon dioxide and water vapor upon heating. Properties and purposes of low-combustibility adhesives, as well as adhesive-combustibility testing methods, are presented.