Correlation Between the Resistance to Stress Corrosion Cracking of Steel Tubes of Gas Pipelines with Their Layerwise Texture Inhomogeneity

In the present work, the influence of the tubes texture layering on their resistance to stress-corrosion cracking (SCC) is demonstrated by the example of several main gas pipelines (MGP) constructed of X70 steel tubes of different manufactures and operated under various exploitation conditions. X-ray studies of crystallographic texture and structural characteristics were implemented for external and internal layers of various tubes sections, which were cut out from MGP zones with fixed SCC defects and without them. Correlation between the depth of corrosion cracks and the thickness of the surface layer with sharply differing texture parameters is established. The system data analysis also shows that the presence of the texture component {110} <001> in the tubes surface layers can increase their resistance to the SCC. Keywords: crystallographic texture, structure, texture layering, electron backscattered diffraction, stress corrosion cracking, main gas pipeline, hot rolling

Physio-mechanical Materials Testing Using Scanning Contact Potentiometry Method

To study the processes of forming and growing embryonic fatigue cracks in steel EI-847 when tested under a uniaxial tension at constant load; adapting the method of scanning contact potentiometry using the INSTRON-5982 machine. The embryo was detected on the sample surface- in the yield point- and stably tracked by theequipment indications at higher loads up to the fracture point. Keywords: scanning contact potentiometry, electrical non-destructive testing, tension testing, fatigue crack, time-frequency signal analysis

Surface Hardening Low Alloy Structural Steel By Laser Welding

The paper studied the degree of surface hardening of various low-alloy structural steels by laser weld overlays. Laser welding carried out on the ”Scanner” and «Huffman HC-205.” Studies have been conducted microstructure and elemental composition of built-up layers and the heat-affected zones on steel substratesselected by scanning electron microscopy and X-ray microanalysis. There were also measured the microhardness and built according to the changes in the thickness microhardness themselves claddings and heat-affected zones. As a result, the optimal modes of application of the laser weld overlays on the substrate, allowing to minimize the size of the heat-affected zones and differences in microhardness values, whichreduces the likelihood of cracks and discontinuities. Keywords: surface hardening, nickel alloy, laser claddin

Microstructural evolution in ODS-EUROFER steel caused by high-dose He ion implantations with systematic variation of implantation parameters

The paper presents a detailed analysis of helium (He) bubble development in ODS-EUROFER steel caused by helium ion implantation in different regimes, with a particular attention to the role of the oxide nanoparticles in promoting the growth of He bubbles, helium accumulation and gas-driven swelling. The Transmission Electron Microscopy (TEM) characterization of steel samples implanted applying systematic variation of experimental parameters has allowed clarifying the trends of the bubble microstructure evolution depending on the implantation dose, flux, and sample temperature. It was found that in all investigated implantation regimes He bubbles formed both in the grain bulk and on various structural defects (dislocations, grain boundaries, oxide particles and carbide precipitates), but the sizes and densities of bubbles in different bubble populations were sensitive to particular irradiation conditions. In the majority of cases the main traps for implanted helium and the main contributors to the estimated swelling were bubbles associated with grain boundaries, though in some cases (high implantation dose or lower temperature) the bubbles in the grain bulk were competitive with the grain boundary bubble population. Oxide particles in ODS-EUROFER were found to be excellent nucleation sites for He bubbles and practically each observed particle hosted a single relatively large bubble, sometimes as large as the particle itself. However, the contribution of oxide-associated bubbles to the estimated swelling and He inventory was found to be minor as compared to other bubble populations because of a relatively low number density of nano-oxides. Comparison of ODS-EUROFER and EUROFER 97 samples implanted with He ions in identical regimes has demonstrated lower efficiency of ODS-EUROFER for accumulating implanted helium in bubbles and noticeably higher share of helium atoms trapped in the vacancy defects invisible by TEM

Magnetic resonances in EuSn2_2As2_2 single crystal

In this work, we report the broad-band ferromagnetic resonance spectroscopy of EuSn$_2$As$_2$ single crystals at different temperatures in combination with magnetization measurements and structural characterization. We observe conventional collective acoustic resonance mode of the A-type antiferromagnetic spin-flop phase in the Eu sub-lattice, and its transition to the paramagnetic resonance above the ordering temperature. Furthermore, we observe reproducibly additional well-defined spectral line. The origin of the additional line remains unclear. However, its temperature dependence attributes it to magnetism in the Eu sub-lattice.Comment: 6 pages, 4 figures, 34 reference

AI is a viable alternative to high throughput screening: a 318-target study

: High throughput screening (HTS) is routinely used to identify bioactive small molecules. This requires physical compounds, which limits coverage of accessible chemical space. Computational approaches combined with vast on-demand chemical libraries can access far greater chemical space, provided that the predictive accuracy is sufficient to identify useful molecules. Through the largest and most diverse virtual HTS campaign reported to date, comprising 318 individual projects, we demonstrate that our AtomNet® convolutional neural network successfully finds novel hits across every major therapeutic area and protein class. We address historical limitations of computational screening by demonstrating success for target proteins without known binders, high-quality X-ray crystal structures, or manual cherry-picking of compounds. We show that the molecules selected by the AtomNet® model are novel drug-like scaffolds rather than minor modifications to known bioactive compounds. Our empirical results suggest that computational methods can substantially replace HTS as the first step of small-molecule drug discovery

Electrochemical dissolution of nickel-rheniumcontaining alloys

This work is devoted to the study of electrochemical dissolution of nickel-rhenium (10% wt.) alloy and nickel-rhenium (20% wt.) alloy. The study was carried out under pulsed current in acidic electrolytes (sulfuric, nitric and hydrochloric acids). It was established that the highest dissolution rate of alloys was achieved at the current pulse amplitude of 1.0-1.5 A, current pulse duration of 500 ms, pause between pulses 50 ms. It is difficult to know exactly which areas meet the electrochemical reaction, but at the expense of depolarization the polarization curve is divided into several sections, each of which correspond to electrochemical reactions. It was shown that both the galvanostatic and potentiostatic modes occur in the selective dissolution of nickel and rhenium. Moreover, the rate of dissolution of nickel and rhenium depends on the acidic electrolyte (sulfuric acid, nitric acid, hydrochloric acid), the ratio of the concentrations of components in the solution, and the content of nickel and rhenium on the surface of the alloy in the nickel-rhenium (10% wt.) and nickel-rhenium (20% wt.) alloys. It was revealed that the highest dissolution rate for the nickel-rhenium (10% wt.) alloy (10.76 g/A·h) is achieved by dissolving in nitric acid, which is less than the dissolution rate of the nickelrhenium (20% wt.) alloy (12.08 g/A·h) in nitric acid. In contrast, in sulfuric and hydrochloric acids the dissolution rate of nickel-rhenium (20% wt.) alloy is much higher compared to the nickel-rhenium (10% wt.) alloy