The analytical capabilities of wavelength-dispersive X-ray fluorescence spectrometry (WDXRF) for determination of total sulfur content in corrosion deposits formed on oil refinery and petrochemical processing equipment are evaluated to prevent equipment failures. Deposit samples collected from diverse process equipment exposed to corrosive environments have been analyzed. The total sulfur content was determined using the standard-free method of fundamental parameters and calibration dependences plotted at the reference samples analysis using regression models. Samples of corrosion deposits of technological equipment containing iron sulfides and sulfates were taken as reference materials. The sulfur content in them was determined gravimetrically. A preliminary study was conducted to estimate the influence of other sample components on the results of sulfur determination. It was found that when plotting calibration dependences, it is necessary to take into account not only the concentration of Fe (matrix), but also the other significant elements such as Ca. For the correct sulfur determination its prevalent valence form should be also considered: sulfate form is confirmed by the satellite SKβ’ peak in XRF spectrum. The developed technique allows the express monitoring of equipment at oil and gas facilities predicting remaining service life, and evaluating operational risks.

The analytical characteristics of the atomic emission spectrometry (AES) technique with the powder sample introduction into a horizontal arc discharge (AD) by the spillage-injection method using an argon medium to determine various elements in silicon, including boron and phosphorus. It is shown that the use of argon medium in the upgraded electric arc setup of «Grand-Potok» spectrometer with the introduction of powder samples by the spillage-injection technique allowed the development of a new express technique for the industrial silicon analysis which has better metrological characteristics in the determination of boron and phosphorus than previously used methods of X-ray fluorescence analysis (XRF), atomic emission spectrometry with inductively coupled plasma (ICP AES) and arc discharge (AES-AD) with vaporation of the sample from the channel. The proposed technique provides to determine the impurities of Fe, Al, Ca, Cu, Ti, Mn, Ni and V: its metrological characteristics are comparable to those of XFF and ICP AES methods for Fe, Al, Ca, and Cu and are worse for Ti, Mn, Ni, and V determination. The technique is characterized by expressiveness (the time of a single measurement is about 20 sec), the absence of complex sample preparation (it is enough to grind the sample to a particle size of 200 mesh), representativeness (1200 mg per sample) and low detection limits of B and P — 2 × 10^–5 and 1 × 10^–4 %, respectively.

New metal-affinity sorbents based on lanthanide stearates have been developed, characterized and studied in the «laboratory on target» format. In the course of the Langmuir method, adapted to the hemispherical surface of the droplet, 13 new sorbents were formed on the surface of the target for matrix-activated laser desorption/ionization mass spectrometry (MALDI), representing collapsed thin films (monolayers) of cerium, praseodymium, neodymium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium and lutetium stearates. The methods of optical microscopy, scanning electron microscopy, and atomic force microscopy have shown that spots of a material with a developed surface are formed on the target. Using MALDI MS, it was determined that the main structural unit is a metal distearate with one labile valence. All structures exhibit specificity towards chlorine-containing adducts, which confirms their metal-affinity properties. When conducting metal-affinity extraction in the «laboratory on target» format, sorbents based on ytterbium, thulium, erbium, gadolinium, neodymium, and cerium stearates exhibit the most pronounced metal-affinity properties, a good level of specificity and selectivity. Gadolinium stearate-based structures can be attributed to universal metal-affinity sorbents that have great prospects in bioorganic analysis. Metal-affinity sorbents containing neodymium, praseodymium, gadolinium, dysprosium, holmium, thulium and lutetium have been investigated and described for the first time.

Martensitic steels of the Kh13 type, such as 20Kh13 and 40Kh13, are widely used, for example, in the production of medical instruments. This study presents the results of assessing the susceptibility to intergranular corrosion (IGC) of 20Kh13 and 40Kh13 steels in their initial state (after hot rolling) and after heat treatment (annealing to produce granular pearlite) using the AMUF accelerated test method. The microstructure was analyzed using scanning electron microscopy, along with the chemical composition and hardness of the investigated steels. It was found that after annealing, 20Kh13 steel exhibits a higher susceptibility to IGC compared to 40Kh13, despite their similar structural characteristics. This is attributed to differences in the morphology of the carbide phase — smaller and more uniformly distributed carbides in 40Kh13 provide better corrosion resistance. The obtained results can be used to improve the methodology for evaluating the susceptibility of martensitic steels to IGC, thereby enabling more reliable quality assessment of medical instruments and predicting their service life.

The paper presents the results of studying the influence of preliminary magnetic treatment on the thermoplastic effect in aluminum alloys with ferromagnetic inclusions. The samples were exposed to a constant magnetic field with subsequent creep tests under uniaxial tension. Scanning electron microscopy, energy-dispersive spectroscopy, and X-ray diffraction analysis were used to analyze the alloy morphology. Specific heat and work of plastic deformation were calculated based on thermomechanical data. It was revealed that there is a relationship between magnetostriction, mechanical stresses at the matrix-inclusion boundary, and energy dissipation during deformation. It was found that preliminary magnetic exposure of samples increases the specific heat by 5 times (from 0.05 to 0.26 J/m³) and the work of deformation by 44 % (from 0.72 to 1.04 J/m³). The increase in the Taylor coefficient (from 0.07 to 0.25) and latent energy (from 0.67 to 0.78 J/m³) is associated with the redistribution of stresses at the matrix-inclusion boundary due to magnetostriction. When assessing the mechanical stresses caused by magnetostriction, the obtained values exceed the yield strength of the matrix, which explains the increase in energy dissipation. The results obtained can be used in the development of «smart» materials with programmable properties due to variations in the composition, size and concentration of the magnetoactive filler in the non-magnetic matrix.

The method of spectral analysis of the envelope of high-frequency vibration signal components is used to identify defects and assess the condition of rolling bearings. The disadvantage of this approach is the high loss of useful signal as the vibration transducer moves away from the product being diagnosed. The paper presents the results of the diagnosis of rolling bearing defects using the analysis of the envelope spectrum of the acoustic pressure signal obtained using measuring microphones. The vibration and acoustic radiation of a serviceable support bearing and a bearing with a defect artificially applied to its inner race were analyzed. It is shown that the identification of rolling bearing defects by acoustic pressure signals has limitations due to the fact that sound reflection, background noise and interference can mask useful signals. The presence of random spatial noise leads to a low signal-to-noise ratio, however, microphones located close to the damaged bearing make it possible to determine the presence of a defect and its type. The obtained results can be used to improve the methods of diagnostics and monitoring of the technical condition of rolling bearings.

A test procedure for models of transport packaging sets (TPSs) for spent nuclear fuel for external shock effects (falling on a pin, falling on dampers, impact of a falling aircraft) is presented, taking into account large-scale effects and the presence of technological defects in the TPS body. The main idea of the technique is that artificial crack-like defects are created in the body of the model in the area of maximum tensile stresses. Their dimensions are determined by the technological defects of forgings, castings, welds, the scale of the layouts, and the dispersion of the fracture toughness characteristics of the body material. The conservativeness of the simulation test results is ensured by the fact that the probability of destruction of a mock-up with artificial defects exceeds the probability of destruction of a full-scale TPS. The results of calculations of the stress-strain state and strength of mock-ups of transport packaging sets (TPSs) for the BREST-OD-300 during throwing tests and impact tests of a falling aircraft are presented. Using the concept of a master curve, the probabilities of destruction of full-scale TPS and reduced layouts were estimated depending on the test temperature. It is shown that the steel 09N2MFBA-A used for the manufacture of TPS housings has high dynamic fracture toughness, ensuring the integrity of the TPS at temperatures lowered to –60°C.

The article presents the results of methodological developments aimed at studying the distribution of residual stresses across the thickness of thin-sheet rolled materials. The specimens subject to direct testing are narrow strips cut from the workpiece along and across the rolling direction. The determination of stresses in the specimen is performed by the method of gradually deepening transverse slit. As a registered response, it is proposed to consider the angle of the arising mutual rotation of the end parts of the sample. For its reliable registration, the most optimal non-contact optical methods should be considered: electronic speckle pattern interferometry or digital image correlation. The choice of a specific one is determined by the test conditions. The procedure for interpreting primary experimental information in terms of residual stresses is formulated as an inverse problem of solid mechanics. Two possible mathematical approaches to data processing are considered, taking into account the incorrectness of the problem statement. Stabilization of the solution is achieved, among other things, through the use of a regularization algorithm. The efficiency of the performed developments is demonstrated by the study’s example of stress distributions in specimens of thin-sheet rolled steel — products of the Novolipetsk Metallurgical Plant. It is shown that different approaches to mathematical processing give practically identical results.

The purpose of this work is to evaluate the mechanical anisotropy of structures additively manufactured from heat-resistant steels under conditions where the dimensions of the workpiece do not allow cutting samples in three mutually perpendicular directions. The material for this research was cylindrical specimens from SS 316L alloy plates prepared through direct laser deposition with process parameters, providing mechanical properties of large-scale structures. The quasi-static isothermal tension tests up to fracture under room temperature and elevated temperatures carried out on specimens extracted along two possible orientations (namely: the build direction and the print direction) shown the similarity of the flow curves in these directions, which might be associated with the small degree of mechanical anisotropy of the workpiece. In contrast, the cross-section of the round bar specimen after tension becomes elliptical — both in the necking part of the specimen and in the part of uniform elongation, which demonstrates the persistence of anisotropy in the workpieces related with the difference of mechanical properties in the third, unstudied direction. On the basis of numerical simulation of the specimen’s deformation via finite element method in the ANSYS package a mathematical description of the material was constructed, providing coincidence of the simulated behavior with the experimental one — both in the load-elongation curve and in the cross-section ellipticity of the specimen. Typical for additive manufacturing method thermally stressed structure was numerically simulated to estimate the influence of the material anisotropy on structural strength. It is shown that taking into account anisotropy reduces the assessed cyclic durability by approximately two times. The performed work gives a reason for a more complete study of anisotropy, despite the methodological difficulties, such as manufacturing of sufficiently large 3D-printed workpieces, and additional amount of experimental work.

The standard method of dynamic mechanical analysis used for determining the viscoelastic properties of highly elastic materials. The method involves testing bulk samples of a certain shape and size. We present the results of a study of the viscoelastic properties of nitrile butadiene rubbers using the dynamic mechanical analysis (nanoDMA) method. A new experimental installation for nanodynamic testing of frost-resistant rubbers in the temperature range from –60 to 60°C was used. The applied technique included studying samples in a local near-surface region. For testing by the nanoDMA method, the required parameters were set in the software of the indenting module: load, frequency and amplitude of indenter oscillations, test duration. The module allows to install an indenter of different geometry and material. It was found that at low temperatures close to the glass transition temperature, a sharp change in the properties of rubbers occurs. Temperature dependences of the elastic modulus at frequencies of 0.1, 0.2, 0.5, 1, 6, and 30 Hz showed a significant change in the properties of samples at temperatures of about –40°C. The proposed experimental installation can be used for quality control of products, for example, in the form of rings intended for tribological testing.