scholarly journals Operation influence on structural and phase condition of 0.12C-1Cr-1Mo-1V-Fe steel

2020 ◽  
pp. 57-62
Author(s):  
N.A. Popova ◽  
◽  
E.L. Nikonenko ◽  
N.V. Ababkov ◽  
A.N. Smirnov ◽  
...  
Keyword(s):  
Phase Composition ◽  
Term Operation ◽  
Prolonged Operation ◽  
Transmission Electron ◽  
Phase Condition ◽  
Elastic Distortion ◽  
Diffraction Microscopy ◽  
Carbide Component ◽  
Electron Diffraction Microscopy

By the method of transmission electron diffraction microscopy the study of 0.12C-1Cr-1Mo-1V-Fe steel samples subjected to various long-term operation was conducted: 1) on the unfinished sample, 2) after prolonged operation without sample destruction, and 3) after prolonged operation brought to sample destruction. For each sample the phase composition was determined and the change in morphology of the structure was studied. It is established that operation of steel leads, firstly, to the destruction of plate pearlite and intensive ferrite fragmentation, secondly, to the redistribution of carbide component and, thirdly, to elastic distortion of the crystal lattice.

Physical Nature of Structure and Properties Degradation of Rail Surface after Long Term Operation

2018 ◽  
Vol 30 ◽  
pp. 39-45
Author(s):  
Victor E. Gromov ◽  
Anton A. Yuriev ◽  
Oleg A. Peregudov ◽  
Sergey V. Konovalov ◽  
Yurii F. Ivanov ◽  
...  
Keyword(s):  
Physical Nature ◽  
Surface Layers ◽  
Term Operation ◽  
Optical Scanning ◽  
Transmission Electron ◽  
Dynamical Recrystallization ◽  
Parameters Measurement ◽  
Diffraction Microscopy ◽  
Electron Diffraction Microscopy

By methods of optical, scanning and transmission electron diffraction microscopy and microhardness and tribology parameters measurement the changes regularities of structure-phase states, defect substructure of rails surface after the long term operation (passed tonnage of gross weight 500 and 1000 mln. tons) were established. It is shown that the wear rate increases in 3 and 3.4 times after passed tonnage of gross weight 500 and 1000 mln. tons, accordingly, and the friction coefficient decreases in 1.4 and 1.1 times. The cementite plates are destroying absolutely and cementite particles of around form with the sizes 10-50 nm are forming after passed tonnage 500 mln tons. The appearance of dynamical recrystallization initial stages is marked after the passed tonnage 1000 mln tons. It is shown that the operation of steel rails is accompanied by full fractures in surface layers with lamellar pearlite grains and the formation of ferrite–carbide mixtures with nanosized particles. The deformation of steel increases the densities of scalar and excess dislocations, the curvature–torsion values of the crystal lattice, and the amplitudes of internal stress fields. The possible mechanisms of established regularities are discussed. It is noted that two competitive processes can take place during rails long term operation: 1. Process of cutting of cementite particles followed by their carrying out into the volume of ferrite grains or plates (in the structure of pearlite). 2. Process of cutting, the subsequent dissolution of cementite particles, transition of carbon atoms to dislocations (into Cottrell atmospheres), transition of carbon atoms by dislocations into volume of ferrite grains or plates followed by repeat formation of nanosize cementite particles.

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.

Characteristic of Crystallite Sizes and Lattice Deformations Changes in the Oxide Layer Formed on Steel Operated for a Long Time at an Elevated Temperature

2013 ◽  
Vol 203-204 ◽  
pp. 204-207 ◽  
Author(s):  
Monika Gwoździk
Keyword(s):  
Phase Composition ◽  
Elevated Temperature ◽  
Oxide Layer ◽  
Flue Gas ◽  
Phase Identification ◽  
X Ray ◽  
Term Operation ◽  
Long Time ◽  
Crystallite Sizes

The paper presents results of studies on the phase composition, crystallite sizes and lattice deformations of oxide layers formed during a long-term operation on X10CrMoVNb9-1 steel. Test specimens were taken from a live steam pipeline operated at 535°C for 70,000 hours. X-ray studies were carried out on the tube outside surface (on the flue gas side), then the layer’s surface was polished and the diffraction measurements repeated to reveal differences in the originated oxides layer. X-ray phase analysis was performed using a SEIFFERT 3003 T/T X-ray diffractometer, with a cobalt tube of λCo= 0.17902nm wavelength. crystallographic database were used for the phase identification.

scholarly journals Changes In Properties and Microstructure of High-Chromium 9-12%Cr Steels Due to Long-Term Exposure at Elevated Temperature

2016 ◽  
Vol 61 (2) ◽  
pp. 957-964 ◽  
Author(s):  
A. Zieliński ◽  
J. Dobrzański ◽  
H. Purzyńska ◽  
G. Golański
Keyword(s):  
Electron Microscopy ◽  
Mechanical Properties ◽  
Transmission Electron Microscopy ◽  
Phase Composition ◽  
High Chromium ◽  
X Ray ◽  
Supercritical Steam Parameters ◽  
Transmission Electron ◽  
Steam Parameters

AbstractThis paper presents the characteristics of the performance of P91 (X10CrMoVNb9-1), P92 (X10CrWMoVNb9-2) and VM12 (X12CrCoWVNb12-2-2) steels used for condition assessment of the pressure components of boilers with supercritical steam parameters. Studies on the mechanical properties, microstructure tests using scanning and transmission electron microscopy, and X-ray analysis of the phase composition of precipitates were performed for selected steels in the as-received condition and after long-term annealing. These steel characteristics are used for the evaluation of the microstructural changes and mechanical properties of the material of components after long-term service. The result of this study is the database of material characteristics representing the mechanical properties related to the microstructure analysis and it can be used for diagnosis of the components of pressure parts of power boilers.

Structural Analysis of В4С Bimodal Powder Mixture

2015 ◽  
Vol 1085 ◽  
pp. 197-200
Author(s):  
Мaria S. Petukevich ◽  
Yuri F. Ivanov ◽  
Oleg L. Khasanov ◽  
Edgar S. Dvilis ◽  
Alexandra A. Panina
Keyword(s):  
Carbide Powder ◽  
X Ray Diffraction ◽  
Nanosized Powder ◽  
Powder Mixtures ◽  
X Ray ◽  
Transmission Electron ◽  
Composition And Structure ◽  
Powder Particles ◽  
Diffraction Microscopy ◽  
Electron Diffraction Microscopy

Phase composition and structure of boron carbide powder with dispersion of particles varying from 30 nanometers to 0.8 micrometers were investigated by the methods of X-ray diffraction, scanning and transmission electron diffraction microscopy. It was obtained bimodal powder mixtures with relatively quasi-uniform distribution of nanosized powder particles.

scholarly journals On the long-term aging of S-phase in aluminum alloy 2618A

2021 ◽  
Vol 56 (14) ◽  
pp. 8704-8716
Author(s):  
Christian Rockenhäuser ◽  
Christian Rowolt ◽  
Benjamin Milkereit ◽  
Reza Darvishi Kamachali ◽  
Olaf Kessler ◽  
...  
Keyword(s):  
Aluminum Alloy ◽  
Elevated Temperatures ◽  
Prediction Models ◽  
S Phase ◽  
Scanning Calorimetry ◽  
Term Operation ◽  
Transmission Electron ◽  
Long Time ◽  
Engine Components

AbstractThe aluminum alloy 2618A is applied for engine components such as radial compressor wheels which operate for long time at elevated temperatures. This results in coarsening of the hardening precipitates and degradation in mechanical properties during the long-term operation, which is not taken into account in the current lifetime prediction models due to the lack of quantitative microstructural and mechanical data. To address this issue, a quantitative investigation on the evolution of precipitates during long-term aging at 190 °C for up to 25,000 h was conducted. Detailed transmission electron microscopy (TEM) was combined with Brinell hardness measurements and thorough differential scanning calorimetry (DSC) experiments. The results show that GPB zones and S-phase Al2CuMg grow up to < 1,000 h during which the GPB zones dissolve and S-phase precipitates form. For longer aging times, only S-phase precipitates coarsen, which can be well described using the Lifshitz–Slyozov–Wagner theory of ripening. A thorough understanding of the underlying microstructural processes is a prerequisite to enable the integration of aging behavior into the established lifetime models for components manufactured from alloy 2618A.

The Influence of Electron Beam Treatment on Al-Si Alloy Structure Destroyed at High-Cycle Fatigue

2016 ◽  
Vol 675-676 ◽  
pp. 655-659 ◽  
Author(s):  
Sergey V. Konovalov ◽  
Krestina Aksenova ◽  
Victor Gromov ◽  
Yurii F. Ivanov ◽  
Olga Semina
Keyword(s):  
Electron Beam ◽  
Electron Beam Irradiation ◽  
High Cycle Fatigue ◽  
Fatigue Loading ◽  
Electron Beam Treatment ◽  
Electron Beam Processing ◽  
Transmission Electron ◽  
Microscopy Method ◽  
Diffraction Microscopy ◽  
Electron Diffraction Microscopy

By scanning and transmission electron diffraction microscopy method the analysis of structure-phase states and defect substructure of silumin subjected to high-intensity electron beam irradiation in various regimes and subsequent fatigue loading up to failure was carried out. It is revealed that the sources of fatigue microcracks are silicon plates of micron and submicron sizes that are not soluble in electron beam processing. The possible reasons of the silumin fatigue life increase under electron-beam treatment are discussed.

EELS characterization of “Smut” layer films on steel surface prepared for chrome plating by anodic etching

1995 ◽  
Vol 53 ◽  
pp. 538-539
Author(s):  
E Y. Wang ◽  
J. T. Cherian ◽  
A. Madsen ◽  
R. M. Fisher
Keyword(s):  
Steel Surface ◽  
Surface Preparation ◽  
Treatment Method ◽  
Chrome Plating ◽  
Transmission Electron ◽  
Alloy Steels ◽  
Pre Treatment ◽  
Hard Chrome ◽  
Electron Energy Loss

Many steel parts are electro-plated with chromium to protect them against corrosion and to improve their wear-resistance. Good adhesion of the chrome plate to the steel surface, which is essential for long term durability of the part, is extremely dependent on surface preparation prior to plating. Recently, McDonnell Douglas developed a new pre-treatment method for chrome plating in which the steel is anodically etched in a sulfuric acid and hydrofluoric acid solution. On carbon steel surfaces, this anodic pre-treatment produces a dark, loosely adhering material that is commonly called the “smut” layer. On stainless steels and nickel alloys, the surface is only darkened by the anodic pre-treatment and little residue is produced. Anodic pre-treatment prior to hard chrome plating results in much better adherence to both carbon and alloy steels.We have characterized the anodic pre-treated steel surface and the resulting “smut” layer using various techniques including electron spectroscopy for chemical analysis (ESCA) on bulk samples and transmission electron microscopy (TEM) and electron energy-loss spectroscopy (EELS) on stripped films.

Ultrastructural observations of the aorta of calves implanted with a mechanical left ventricular assist device

1990 ◽  
Vol 48 (3) ◽  
pp. 834-835
Author(s):  
J P Cassella ◽  
V Salih ◽  
T R Graham
Keyword(s):  
Left Ventricular Assist Device ◽  
Ventricular Assist Device ◽  
Left Ventricular ◽  
Aortic Tissue ◽  
Assist Device ◽  
Ventricular Assist ◽  
Transmission Electron ◽  
Left Ventricular Assist ◽  
Preliminary Study

Left ventricular assist systems are being developed for eventual long term or permanent implantation as an alternative to heart transplantation in patients unsuitable for or denied the transplant option. Evaluation of the effects of these devices upon normal physiology is required. A preliminary study was conducted to evaluate the morphology of aortic tissue from calves implanted with a pneumatic Left Ventricular Assist device-LVAD. Two 3 month old heifer calves (calf 1 and calf 2) were electively explanted after 128 days and 47 days respectively. Descending thoracic aortic tissue from both animals was removed immediately post mortem and placed into karnovsky’s fixative. The tissue was subsequently processed for transmission electron microscopy (TEM). Some aortic tissue was fixed in neutral buffered formalin and processed for routine light microscopy.

Sign in / Sign up

Export Citation Format

Share Document