scholarly journals Development of the structure of differentially hardened 100 m rails during their long operation

2020 ◽  
Vol 63 (2) ◽  
pp. 108-115 ◽  
Author(s):  
V. E. Kormyshev ◽  
E. V. Polevoi ◽  
A. A. Yur’ev ◽  
V. E. Gromov ◽  
Yu. F. Ivanov
Keyword(s):  
Impact Strength ◽  
Strain Hardening ◽  
Cross Section ◽  
Materials Science ◽  
Structural Phase ◽  
Term Operation ◽  
Rail Head ◽  
Rolling Surface ◽  
Head Surface

Using methods of modern physical materials science, structural-phase states and mechanical properties of the rolling surface have been analyzed at distance of 0 to 22 mm along the central axis and along the fillet of differentially hardened 100 m rails of DT 350 category manufactured by JSC “EVRAZ – United West Siberian Metallurgical Plant” after their long-term operation (passed gross tonnage of 1.411 million tons) on experimental test ring. In terms of chemical composition, metal of the rails meets TU 0921-276-01124323 – 2012 requirements for E76KhF steel. Impact strength and hardness on head surface and along cross-section meet TU specifications. Microstructure of rails metal is represented by finely dispersed plate perlite of 1.5 points with inclusions of excessive ferrite along the grain boundaries (1.5 points by GOST 8233 scale No. 7). Interlamellar distance in the rail head varies between 0.10 and 0.15 microns. Long-term operation of rails is accompanied by development of gradient structure, manifested in regular change in hardness, microhardness, impact strength along cross-section of the rail head. Microhardness at 2 mm depth from the rolling surface is 1481 – 1486 MPa. At 10 mm depth microhardness decreases to 1210 – 1385 MPa, which is caused by an increase in interlamellar distance and decrease in the level of strain hardening of metal during long-term operation of rails. It has been suggested that this may be due to an increase in interlamellar distance and a decrease in level of strain hardening during long-term operation.

Analysis of crystallite size changes in a hematite and magnetite formed on steel used in the power idustry

2017 ◽  
Vol 1 (21) ◽  
pp. 65-73
Author(s):  
Monika Gwoździk
Keyword(s):  
Elevated Temperature ◽  
Oxide Layer ◽  
Cross Section ◽  
X Ray ◽  
Term Operation ◽  
Diffraction Line Profile ◽  
Crystallite Sizes ◽  
Scherrer Formula ◽  
Pipe Outlet

The paper presents results of studies on the crystallite sizes of oxide layer formed during a long-term operation on 10CrMo9-10 steel at an elevated temperature (T = 545° C, t = 200,000 h). This value was determined by a method based on analysis of the diffraction line profile, according to a Scherrer formula. The oxide layer was studied on a surface and a cross-section at the outer and inner site on the pipe outlet, at the fire and counter-fire wall of the tube. X-ray studies were carried out on the surface of a tube, then the layer’s surface was polished and the diffraction measurements repeated to reveal differences in the originated oxides layer.

scholarly journals Physical Nature of Strengthening Mechanisms During Extremely Long-Term Operation of Rails

2021 ◽  
pp. 33-39
Author(s):  
Yu.F. Ivanov ◽  
A.A. Yuriev ◽  
V.E. Kormyshev ◽  
X. Chen ◽  
V.B. Kosterev ◽  
...  
Keyword(s):  
Surface Layer ◽  
Relative Content ◽  
Formation Mechanisms ◽  
Strengthening Mechanisms ◽  
Near Surface ◽  
Term Operation ◽  
Rail Head ◽  
Metal Volume ◽  
Lamellar Pearlite

The quantitative estimation of strengthening mechanisms of rails’ surface layer is carried out on the basis of regularities and formation mechanisms of structure-phase states revealed by the methods of modern physical materials science. It is performed at different depths of the rail head along the central axis and fillet of differentially quenched 100-meter rails after the extremely long-term operation (gross passed tonnage of 1411 mln tons). A long-term operation of rails is accompanied by the formation of structural constituent gradient consisting of a regular change in the relative content of lamellar pearlite, fractured pearlite, the structure of ferrite-carbide mixture, scalar, and excess dislocation density along the cross-section of the rail head. As the distance to the rail fillet surface decreases, the relative content of metal volume with lamellar pearlite decreases. However, the relative content of metal volume with the presence of the fractured pearlite structure and ferrite-carbide mixture increases. The contributions caused by the matrix lattice friction, intraphase boundaries, dislocation substructure, presence of carbide particles, internal stress fields, solid-solution strengthening, pearlite component of steel structure are estimated. It is shown that the main mechanism of strengthening in the surface layer is due to the interaction of moving dislocations with low-angle boundaries of nanometer dimensional fragments and subgrains. The main dislocation strengthening mechanism in a near-surface layer at a depth of 2-10 mm is due to the interaction of moving dislocations with immobile ones.

scholarly journals REDISTRIBUTION OF CARBON ATOMS IN DIFFERENTIALLY CHARGED RAILS FOR LONG-TERM OPERATION

2018 ◽  
Vol 61 (6) ◽  
pp. 454-459 ◽  
Author(s):  
V. E. Gromov ◽  
A. A. Yur’ev ◽  
Yu. F. Ivanov ◽  
V. A. Grishunin ◽  
S. V. Konovalov
Keyword(s):  
Surface Layer ◽  
Phase Composition ◽  
Materials Science ◽  
Rail Steel ◽  
Ferrite Matrix ◽  
Crystalline Lattice ◽  
Initial State ◽  
Term Operation ◽  
Prolonged Operation ◽  
Rolling Surface

Using  transmission  electron  microscopy  methods  at  various  distances from the rolling surface along the central axis, changes in  structure, phase composition, and defective substructure of the head  of differentially hardened rails were studied after passed tonnage of  691.8  million tons of gross weight. It is confirmed that prolonged  operation of rails is accompanied by two simultaneous processes of  transformation of structure and phase composition of plate-pearlite  colonies: cutting of cementite plates and dissolution of cementite  plates. The first process is carried out by mechanism of cutting carbide  particles and removing their fragments, accompanied only by change  in their linear dimensions and morphology. The second process of  dest ruction of the cementite plates of perlite colonies is carried out by  leaving carbon atoms from crystalline lattice of cementite on dislocation, as a result of which phase transformation of rails metal is possible. This is due to a noticeable relaxation of mean energy of carbon  atom  s binding to dislocations (0.6  eV) and to iron atoms in cementite  lattice (0.4  eV). The stages of transformation of cementite plates are considered: enveloping the plates with sliding dislocations and then  splitting them into weakly oriented fragments; penetration of sliding  dislocations from ferrite lattice into lattice of cementite; dissolution of  cementite and formation of nanoscale particles. The presence of nanosized cementite particles in ferrite matrix is noted due to their removal  during dislocation slide. Using expressions of modern physical materials science and X-ray diffraction analysis, influence of content of  carbon atoms on structural elements of rail steel was estimated. It is  shown that prolonged operation of rails is accompanied by a significant  redistribution of carbon atoms in surface layer. In the initial state, the  main quantity of carbon atoms is concentrated in cementite particles,  and after a long operation of rails, along with cementite particles, carbon is located in defects of crystal structure of steel (dislocation, grain  boundaries and subgrains), and in the surface layer of steel atoms carbon is also found in crystal lattice based on α-iron.

scholarly journals Evaluation of high-temperature corrosion on 13CrMo4-5 steel operated in the power industry

2018 ◽  
Vol 4 (21) ◽  
pp. 335-343
Author(s):  
Monika Gwoździk
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Elevated Temperature ◽  
Oxide Layer ◽  
Cross Section ◽  
High Temperature Corrosion ◽  
X Ray ◽  
Term Operation ◽  
Scanning Electron

The paper presents results of studies of steel and the oxide layer formed during a long-term operation (t=130,000h) on 13CrMo4-5 steel at an elevated temperature (T=455°C). The oxide layer was studied on a surface and a cross-section at the inner site of the pipe (in the flowing medium – steam side). The paper contains results of studies such as: light microscopy, scanning electron microscopy, X-ray phase analysis.

scholarly journals Formation Structural Phase Gradients in Rail Steel During Long-Term Operation

2016 ◽  
Vol 112 ◽  
pp. 012038 ◽  
Author(s):  
Yu F Ivanov ◽  
K V Morozov ◽  
O Peregudov ◽  
V E Gromov ◽  
N A Popova ◽  
...  
Keyword(s):  
Rail Steel ◽  
Structural Phase ◽  
Term Operation

Structural phase states and properties of rails after long-term operation

2020 ◽  
Vol 268 ◽  
pp. 127499 ◽  
Author(s):  
V.E. Kormyshev ◽  
V.E. Gromov ◽  
Yu.F. Ivanov ◽  
A.M. Glezer ◽  
A.A. Yuriev ◽  
...  
Keyword(s):  
Structural Phase ◽  
Term Operation

Structure and Properties of Lengthy Rails after Extreme Long-Term Operation

2021 ◽  
Author(s):  
A.A. Yuriev ◽  
V.E. Gromov ◽  
Yu.F. Ivanov ◽  
Yu.A. Rubannikova ◽  
M.D. Starostenkov ◽  
...  
Keyword(s):  
Plastic Deformation ◽  
Structural Phase ◽  
Internal Stresses ◽  
Structure And Properties ◽  
Surface Layers ◽  
Nanoscale Structures ◽  
Term Operation ◽  
Methods And Techniques ◽  
And Behavior

The long-term operation of rails has been studied with focus on (1) the formation and behavior of structural-phase states and nanoscale structures, (2) the modelling of the processes occurring in the surface layers of rails under severe plastic deformation and (3) the methods and techniques for assessing the structural and phase states of rails, internal stresses, and their evolution during the life cycle. The book references 264 original resources and includes their direct web link for in-depth reading.

scholarly journals Model of nanostructural layers formation at long-term operation of rails

2020 ◽  
Vol 63 (9) ◽  
pp. 699-706
Author(s):  
V. D. Sarychev ◽  
S. A. Nevskii ◽  
V. E. Kormyshev ◽  
A. A. Yur’ev ◽  
V. E. Gromov
Keyword(s):  
Growth Rate ◽  
Graphical Representation ◽  
Stokes Equations ◽  
Rail Steel ◽  
Structural Phase ◽  
Wave Number ◽  
Fluid Viscosity ◽  
Plastic Deformations ◽  
Term Operation

A mathematical model was developed and a mechanism was proposed for the formation of nanoscale structural-phase states on the example of rail steel at long-term operation. It was believed that during intense plastic deformations, the material behaves like a viscous incompressible fluid. In order to take into account the sliding of the wheel relative to the rail, a two-layer fluid model was proposed, the top layer of which slides at a certain speed relative to the first. In this case, the Kelvin-Helmholtz instability develops. For each layer, we have written the Navier-Stokes equations and kinematic and dynamic boundary conditions. Solution of the obtained system in the form of normal perturbation modes was carried out on the basis of assumption of the viscous-potential material flow. In this approximation, it was believed that viscosity effects occur only at the layer interface. A dispersion equation was derived, which was analyzed using a graphical representation of the functions included in the analytical solution. A range of characteristics of the material and parameters of the external influence (the velocity of the layer) was established, at which two peaks are observed in dependence of disturbances growth rate on the wave number. The first (hydrodynamic) maximum is due to the motion of the layers relative to each other; the second is associated with the effects of fluid viscosity. Approximate formulas were obtained for dependence of the growth rate of perturbations on the wave number. Conditions for realization of only one maximum were found. The viscously determined maximum at slip velocities of the order of 1 m/s can be in the nanoscale wavelength range. Assuming that the white layer in the rails during long-term operation is formed mainly due to the action of intense plastic deformations, we believe that the obtained results detail the mechanism of white layers formation in the rails in this case.

Hardening mechanisms for rails metal during long-term operation

2020 ◽  
pp. 17-28
Author(s):  
Yu. F. Ivanov ◽  
V. E. Kormyshev ◽  
V. E. Gromov ◽  
A. A. Yuriev ◽  
A. M. Glezer ◽  
...  
Keyword(s):  
Materials Science ◽  
Steel Structure ◽  
Solid Solution Hardening ◽  
Initial State ◽  
Term Operation ◽  
The Matrix ◽  
Interphase Boundaries ◽  
Matrix Lattice ◽  
Different Depths

A quantitative comparative analysis of the mechanisms of hardening of the surface layers of differentially hardened 100-m rails is carried out. It was based on structure formation, phase composition, defect substructure regularities revealed by the methods of modern physical materials science. The studies were carried out at different depths of up to 10 mm in the rail head along the central axis and along the axis of symmetry of the fillet in the initial state and after various periods of extremely long-term operation (passed tonnage of 691.8 and 1411 mln. tons brutto). The contributions due to the friction of the matrix lattice, interphase boundaries, dislocation substructure, presence of carbide particles, internal stress fields, solid-solution hardening of the pearlite component of the steel structure are estimated.

Texturing of Magnetite Forming during Long-Term Operation of a Pipeline of 10CrMo9-10 Steel

2013 ◽  
Vol 203-204 ◽  
pp. 121-124 ◽  
Author(s):  
Monika Gwoździk ◽  
Zygmunt Nitkiewicz
Keyword(s):  
Cross Section ◽  
Oxide Surface ◽  
Initial State ◽  
Radiation Beam ◽  
X Ray ◽  
Term Operation ◽  
Magnetite Layer ◽  
Anode Tube

The paper presents results of X-ray measurements of the texture of a magnetite (Fe3O4) layer formed on 10CrMo9-10 steel during 100,000 hours operation at the temperature of 575°C (in a flowing medium environment). The formed oxide layer was ≈140µm thick. Measurements of texturing were performed on the oxide surface and also at the depth of ≈50µm from the surface (1st polishing) and ≈100µm (2nd polishing). X-ray studies were carried out using the radiation of a cobalt anode tube, λCo=0.17902nm, for (311) and (400) Fe3O4 reflections, using a radiation beam collimated to φ=2mm. The study was aimed at determination of correlation between the texturing and the structure on the magnetite layer cross-section. A clear texturing of {111} and {111} type for the magnetite in the initial state and after the second polishing was found. Instead, after the first polishing there was a substantial texturing of {034} and {015} type. A different nature of the texture may result from a diversified morphology of magnetite at various depths (caused inter alia by a differentiated temperature on the tube wall cross-section during the material operation), which is related among other things to the crystallites size. The magnetite structure and texture changes can affect the magnetite porosity and cleavage.

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