COMPARATIVE ANALYSIS OF THE INFLUENCE OF THE COMPOSITION OF THE ALLOYING COVERING ON THE CHANGE IN THE STRUCTURE AND MICROHARDNESS OF STAINLESS STEEL 12KH18N10T

The article is devoted to the experimental analysis of the influence of the process of laser pulsed alloying in a layer of alloying mixture on the qualitative and physical and mechanical characteristics of the modified surface of stainless chromium-nickel steel of the austenitic class 12Cr18Ni10T. It was found that the use of graphite paste as an alloying compound leads to a significant increase in microhardness, a change in micromorphology, and the formation of a heat hardening zone in the near-surface layer of steel. The smoothing of the boundaries of structural changes is revealed and the effect of surface hardening is determined when a finely dispersed powder of titanium dioxide (anatase) is added to the alloying coating. According to the data obtained, a comparative analysis of the dependence of the microhardness of the modified surface on the voltage of the pump lamp and the diameter of the laser pulse spot is carried out. The maximum microhardness value, equal to 9,56 GPa, was achieved as a result of laser processing of a series of samples, where graphite paste was applied as a preliminary surface preparation. Rational technological modes of laser modification of the surface of 12Cr18Ni10T steel that have previously undergone abrasive blasting, modes of laser pulsed alloying in a layer of graphite coating and laser pulsed alloying of steel in a layer of coating consisting of graphite paste and anatase powder in a ratio of 4:1, respectively, are recommended.

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STUDY OF CHANGE IN WEAR RESISTANCE OF STAINLESS STEEL SURFACE OBTAINED BY LASER PULSE ALLOYING IN THE COATING LAYER

IZVESTIA VOLGOGRAD STATE TECHNICAL UNIVERSITY ◽

10.35211/1990-5297-2021-6-253-61-65 ◽

2021 ◽

pp. 61-65

Author(s):

V. I. Proskuryakov ◽

I. V. Rodionov

Keyword(s):

Wear Resistance ◽

Resistance Index ◽

Laser Pulses ◽

Stainless Steel Surface ◽

Gravimetric Analysis ◽

Nickel Steel ◽

Stainless Chromium ◽

Austenitic Class ◽

Modification Of The Surface ◽

Comprehensive Study

The paper describes an experimental study of laser pulsed modification of the surface of stainless chromium-nickel steel of the austenitic class 12Cr18Ni10T with a graphite coating previously applied to it. The microhardness of the treated surface and its dependence on the modes of laser radiation were determined. The abrasion method was used to study the change in the wear resistance of the modified layer and the possibility of its increase. For a quantitative assessment of the surface resistance to wear, a gravimetric analysis of samples subjected to ball abrasion was carried out, the results of which are fully consistent with the calculation of the dimensionless wear resistance index. It was found that the value of the microhardness is largely influenced by the voltage of the pulses. Thus, the highest microhardness indicators were observed during processing by laser pulses in the voltage ranges of 250-280 V and 340-440 V and take values of 5-6 GPa and 4-5 GPa, respectively. A comprehensive study of abrasion resistance, including the calculation of a dimensionless wear resistance index and an analysis of the weight loss of steel samples as a result of the test, showed that, to the greatest extent, the surface hardening effect is characteristic of samples subjected to treatment with laser pulses focused into a spot 1 mm in diameter at a pulse voltage of range 300-400 V.

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SANDVIK 8R40

Alloy Digest ◽

10.31399/asm.ad.ss0590 ◽

1995 ◽

Vol 44 (4) ◽

Keyword(s):

Corrosion Resistance ◽

High Temperature ◽

Physical Properties ◽

Tensile Properties ◽

Heat Treating ◽

Nickel Steel ◽

Temperature Performance ◽

Stainless Chromium

Abstract SANDVIK 8R40 is an austenitic, columbium stabilized stainless chromium-nickel steel for use at temperatures up to 850 C (1560 F). This datasheet provides information on composition, physical properties, hardness, elasticity, and tensile properties as well as creep. It also includes information on high temperature performance and corrosion resistance as well as forming, heat treating, and joining. Filing Code: SS-590. Producer or source: Sandvik.

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Corrosion of Stainless Chromium-Nickel Steel in Molten Lithium

High-Purity Metals and Alloys ◽

10.1007/978-1-4899-4728-4_20 ◽

1967 ◽

pp. 131-137 ◽

Cited By ~ 1

Author(s):

N. M. Beskorovainyi ◽

V. K. Ivanov ◽

V. V. Petrashko

Keyword(s):

Nickel Steel ◽

Molten Lithium ◽

Stainless Chromium

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Changes in Protein Structural Motifs upon Post-Translational Modification in Kidney Cancer

Diagnostics ◽

10.3390/diagnostics11101836 ◽

2021 ◽

Vol 11 (10) ◽

pp. 1836

Author(s):

Dmitry Tikhonov ◽

Liudmila Kulikova ◽

Vladimir Rudnev ◽

Arthur T. Kopylov ◽

Amir Taldaev ◽

...

Keyword(s):

Immune Response ◽

Comparative Analysis ◽

Kidney Cancer ◽

Conformational Changes ◽

Structural Changes ◽

Biological Function ◽

The Body ◽

Post Translational Modification ◽

Blood Samples ◽

Software Packages

Post-translational modification (PTM) leads to conformational changes in protein structure, modulates the biological function of proteins, and, consequently, changes the signature of metabolic transformations and the immune response in the body. Common PTMs are reversible and serve as a mechanism for modulating metabolic trans-formations in cells. It is likely that dysregulation of post-translational cellular signaling leads to abnormal proliferation and oncogenesis. We examined protein PTMs in the blood samples from patients with kidney cancer. Conformational changes in proteins after modification were analyzed. The proteins were analyzed using ultra-high resolution HPLC-MS/MS and structural analysis was performed with the AMBER and GROMACS software packages. Fifteen proteins containing PTMs were identified in blood samples from patients with kidney cancer. For proteins with PDB structures, a comparative analysis of the structural changes accompanying the modifications was performed. Results revealed that PTMs are localized in stable and compact space protein globule motifs that are exposed to a solvent. The phenomenon of modification is accompanied, as a rule, by an increase in the area available for the solvent of the modified amino acid residue and its active environment.

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Kinetic equations of creep and damage for description of materials with non-monotonic dependence of fracture strain on stress

Metal Working and Material Science ◽

10.17212/1994-6309-2021-23.3-139-154 ◽

2021 ◽

Vol 23 (3) ◽

pp. 139-154

Author(s):

Inna Banshchikova ◽

Keyword(s):

Experimental Data ◽

Comparative Analysis ◽

Damage Accumulation ◽

Elevated Temperatures ◽

Fracture Strain ◽

Least Squares Method ◽

Kinetic Equations ◽

Steel 12Kh18n10t ◽

Static Mode ◽

Creep Curves

Introduction. Reducing the level of damage accumulation during pressure treatment of materials at elevated temperatures in creep and close to superplasticity modes in the manufacture of parts can significantly increase its service life in the cold state. Finding temperature and power conditions leading to a reduction in damage of material during the production process and operation is an important task. The purposes of the work: 1) to show the possibility of using the Sosnin-Gorev creep and damage model for alloys with a non-monotonic dependence of strain at fracture on diagrams with creep curves; 2) to carry out comparative analysis of damage accumulation under conditions of uniaxial tension at constant stress and at constant strain rates for alloy with such a dependence. Research methods. Used scalar damage parameter is equated to the normalized deformation, i.e. to the ratio of the current strain to the fracture strain. To find the coefficients of relations creep and damage, the similarity of the creep curves in the normalized values “normalized strain – normalized time”, i.e. the presence of single normalized curve of damage accumulation is checked. The least squares method is used to approximate the experimental data. Numerical integration methods are used for comparative analysis of deformation modes. Results and discussion. Determination of the parameters of the creep and damage equations by the method of a single normalized curve is carried out on the example of experimental data for steel 12Kh18N10T (12Cr18Ni10Ti) at 850 °C, which has a minimum of fracture strain in diagrams with creep curves. Analysis of the static and kinematic modes of deformation for studied material showed that damage accumulation in both cases is practically the same for stresses close to the stress at which this minimum is reached. If the stresses are lower, then the lower level of damage accumulation will be in the kinematic mode; if the stresses above the minimum value, then the static mode will lead to a lower level of damage accumulation. Application. The obtained results can be useful when choosing rational modes of forming structural elements from alloys with a non-monotonic dependence of the fracture strain on stress, as well as in evaluating it for long-term strength during operation.

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Analysis of Material and Heat Treatment of the High-Pressure Fracturing Pump Valves

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.339.502 ◽

2011 ◽

Vol 339 ◽

pp. 502-505

Author(s):

Qi Ming Yang ◽

Li Jie Yang

Keyword(s):

Heat Treatment ◽

Wear Resistance ◽

Working Life ◽

Nickel Steel ◽

Treatment Technology ◽

The Core ◽

Heat Treatment Technology ◽

Heat Hardening ◽

Wear And Tear ◽

Core Hardness

Fracturing pump valve's failure, except wear and tear factors, and also decided by the scope of it's contact stress, material and heat treatment in technology. Through the analysis of these, some conclusions had been found: The content of remnant austenite would be affected the performance of wear resistance, and the core hardness would be directly affected the working life of it. If the choice of the material and heat treatment technology was not been suitable, and the core intensity was not enough, it could loss the capability of sealing. According to the failure mechanism, used low chrome(nickel) steel, and the heat treatment of carburize+heat hardening+low-temperature tempering was reasonable.

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ON WHEEL–RAIL CONTACT SURFACE PHENOMENA WITH STRUCTURAL CHANGES AND ‘WHITE ETCHING LAYERS’ GENERATION

Transport ◽

10.3846/16484142.2012.696214 ◽

2012 ◽

Vol 27 (2) ◽

pp. 196-205 ◽

Cited By ~ 5

Author(s):

Libor Beneš

Keyword(s):

Structural Changes ◽

Surface Region ◽

Rolling Contact ◽

Contact Friction ◽

Surface Phenomena ◽

Wheel Surface ◽

Near Surface ◽

High Microhardness ◽

Stress Formation ◽

Surface Changes

The main aim of this work was a study of the microstructure transformations with the residual stress formation that is induced by rolling contact friction and adhesive wore in the wheel–rail system. Several small railsurface samples, we term them as the ‘chips’, and a piece of wheel sample were chosen for the analyses of the surface changes on the wheel–rail surface. A multitude of different experiments were carried out in order to analyse the microstructure changes at the surface and the near-surface region of the material samples and, thus, to contribute to the understanding of the complex wheel–rail rolling contact phenomena – and its degradation mechanisms. The formation of nano-structured martensite and carbides on the rail and wheel surface causes the extremely high microhardness valuees and the strong corrosion resistance of the so called White Etching Layers (WEL).

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Comparative Analysis of Bacteriophytochrome Agp2 and Its Engineered Photoactivatable NIR Fluorescent Proteins PAiRFP1 and PAiRFP2

Biomolecules ◽

10.3390/biom10091286 ◽

2020 ◽

Vol 10 (9) ◽

pp. 1286 ◽

Cited By ~ 1

Author(s):

Faez Iqbal Khan ◽

Fakhrul Hassan ◽

Razique Anwer ◽

Feng Juan ◽

Dakun Lai

Keyword(s):

Comparative Analysis ◽

Structural Changes ◽

Near Infrared ◽

Fluorescent Proteins ◽

Irradiation Time ◽

Fluorescence Emission ◽

Emission Spectra ◽

Md Simulations ◽

Fluorescence Emission Spectra ◽

Molecular Stability

Two photoactivatable near infrared fluorescent proteins (NIR FPs) named “PAiRFP1” and “PAiRFP2” are formed by directed molecular evolution from Agp2, a bathy bacteriophytochrome of Agrobacterium tumefaciens C58. There are 15 and 24 amino acid substitutions in the structure of PAiRFP1 and PAiRFP2, respectively. A comprehensive molecular exploration of these bacteriophytochrome photoreceptors (BphPs) are required to understand the structure dynamics. In this study, the NIR fluorescence emission spectra for PAiRFP1 were recorded upon repeated excitation and the fluorescence intensity of PAiRFP1 tends to increase as the irradiation time was prolonged. We also predicted that mutations Q168L, V244F, and A480V in Agp2 will enhance the molecular stability and flexibility. During molecular dynamics (MD) simulations, the average root mean square deviations of Agp2, PAiRFP1, and PAiRFP2 were found to be 0.40, 0.49, and 0.48 nm, respectively. The structure of PAiRFP1 and PAiRFP2 were more deviated than Agp2 from its native conformation and the hydrophobic regions that were buried in PAiRFP1 and PAiRFP2 core exposed to solvent molecules. The eigenvalues and the trace of covariance matrix were found to be high for PAiRFP1 (597.90 nm2) and PAiRFP2 (726.74 nm2) when compared with Agp2 (535.79 nm2). It was also found that PAiRFP1 has more sharp Gibbs free energy global minima than Agp2 and PAiRFP2. This comparative analysis will help to gain deeper understanding on the structural changes during the evolution of photoactivatable NIR FPs. Further work can be carried out by combining PCR-based directed mutagenesis and spectroscopic methods to provide strategies for the rational designing of these PAiRFPs.

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Analyzing Near-Surface Regions of Hydrophobic and Long-Term Weathered Natural Stones at Microscopic Scale

Heritage ◽

10.3390/heritage3020027 ◽

2020 ◽

Vol 3 (2) ◽

pp. 457-473

Author(s):

Franziska Braun ◽

Jeanette Orlowsky ◽

Stefan Brüggerhoff

Keyword(s):

Structural Changes ◽

Color Difference ◽

Outdoor Exposure ◽

Material Surface ◽

Building Structures ◽

Near Surface ◽

Visual Appearance ◽

Microscopic Scale ◽

Surface Damages

The visual appearance of building structures is an important attribute which reflects the character and identity of a region. Due to the influence of weathering, the surfaces of building stones alter, leading to aesthetic changes of the material surface such as discoloration or darkening. In this study, near-surface regions of weathered Baumberger (BST), Schleeriether (SST), and Obernkirchener Sandstones (OKS) have been analyzed at the microscopic scale in order to investigate the intensity and the extent of visual as well as structural changes and how both can be affected due to the presence of surface treatments with hydrophobing agents. It could be detected that aesthetic changes appeared already after 2 years of outdoor exposure, with the slightest variations on BST surfaces, followed by SST and OKS. The use of hydrophobing agents leads to a reduction in surface darkening in the short term. After long-term weathering, no significant changes are visible, as similar values in total color difference (ΔE*) were measured. Biogenic growth and the formation of black weathering crusts are the main reasons for color alterations in the case of the examined stones. The surface damages occur especially on calcareous (BST) followed by clayey (SST) and quartzitic (OKS) stone surfaces.

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