scholarly journals INFLUENCE OF ELECTROLYTIC PLASMA CARBONITRIDING ON STRUCTURAL PHASE STATE OF FERRITIC-PEARLITIC STEELS

2019 ◽  
Vol 62 (10) ◽  
pp. 782-789 ◽  
Author(s):  
N. A. Popova ◽  
E. L. Nikonenko ◽  
A. V. Nikonenko ◽  
V. E. Gromov ◽  
O. A. Peregudov
Keyword(s):  
Surface Area ◽  
Phase State ◽  
Lath Martensite ◽  
Structural Phase ◽  
Central Area ◽  
Original State ◽  
Volume Fractions ◽  
Thin Foils ◽  
Before And After ◽  
Modified Layer

The change in phase composition and fine texture occurring in the  ferritic-pearlitic 0.18C – 1Cr – 3Ni – 1Mo – Fe, 0.3C – 1Cr – 1Mn – 1Si – Fe  and 0.34C – 1Cr – 1Ni – 1Mo – Fe steels under electrolytic plasma carbonitriding  was  investigated  by  transmission  electron  microscopy  (TEM) method conducted on thin foils. Carbonitriding was implemented by surface saturation with nitrogen and carbon in aqueous  solution under the temperature of 800  –  860  °C during 5  minutes. All  steels were investigated before and after carbonitriding. It was ascertained that in the original state steel is given as a mixture of grains  of pearlite and ferrite. Carbonitriding has led to creation of modified  layers: the bigger was the amount of pearlite before the beginning of  carbonitriding, the thicker was modified layer. Carbonitriding resulted  in significant qualitative changes in phase state and structure of steel.  It was revealed that in the surface area of modified layer along the  matrix, there were also particles of other phases: carbides, nitrides and  carbonitrides. In the course of removing from the surface of carbonitrided sample, their complete set and volume fractions decrease and at  the end of modified layer only one carbide phase is present in all steels,  i.e. cementite. It was found that matrix of all steels after carbonitriding is tempered packet (lath) and lamellar martensite. In the surface  area of carbonitrided layer the volume fractions of lath and lamellar  martensite depend on the original state of steel – the bigger was the  amount of pearlite in steel the less lath martensite and the more lamellar martensite was formed. Such a dependency cannot be observed in  the central area, and at the end of carbonitrided layer volume fractions  of martensite packets and plates are commensurate.

scholarly journals Influence of electrolytic plasma nitriding mode on structural phase state of pearlitic steel

2018 ◽  
Vol 143 ◽  
pp. 03004
Author(s):  
Natalya Popova ◽  
Lyudmila Erygina ◽  
Elena Nikonenko ◽  
Mazhin Skakov
Keyword(s):  
Phase State ◽  
Plasma Nitriding ◽  
Water Solution ◽  
Lath Martensite ◽  
Structural Phase ◽  
Pearlitic Steel ◽  
Parallel Plates ◽  
Structural Phase State ◽  
Original State ◽  
Α Phase

The paper describes results of studies of phase transitions in structural phase state occurring in the type 0.34C-1Cr-1Ni-1Mo-Fe steel under electrolytic plasma nitriding in nitrogen-containing water solution. The nitriding voltages considered in the given study were 550 and 600 V. The research was conducted by means of X-ray diffraction electron microscopy. The specimens were studied in two states : 1) before modification (original state) and 2) after nitriding in the surface layer of the specimen. The study was conducted on thin foils. It was found that nitriding lead to significant changes in the structure of steel, namely in its phase composition and in the number of existing phases. In the original state the structure of steel was given as lamellar pearlite, ferritic carbide mix and fragmented ferrite. After 550 V nitriding it was lath martensite, plates of α-phase, with colonies of thin parallel plates of γ-phase and coarse grains of α-phase, containing γ-phase grains which were different in size and shape and were various-directional. Increase in nitriding voltage up to 600 V lead to change in the structure given as a lamellar non-fragmented pearlite and fragmented ferrite. The original state was marked by presence of particles of M3C cementite, after nitriding irrespective of the voltage it had the particles of M3C alloyed cementite, Fe3Mo3N nitride and Cr2C0.61N0.39 carbonitride. The sizes, volume fractions and locations of particles were dependent on nitriding voltage.

scholarly journals Structural-phase transformations in 0.34C–1CRr–1Ni–1Mo–Fe steel during plasma electrolytic hardening

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
B.K. Rakhadilov ◽  
R.S. Kozhanova ◽  
N.A. Popova ◽  
A.B. Nugumanova ◽  
A.B. Kassymov
Keyword(s):  
Phase Transformations ◽  
Surface Hardening ◽  
Structural Phase ◽  
Heat Removal ◽  
Internal Stresses ◽  
Material Surface ◽  
Thin Foils ◽  
Before And After ◽  
Plasma Electrolytic ◽  
Structural Phase Transformations

Abstract Structural-phase transformations in 0.34C–1Cr–1Ni–1Mo–Fe steel during plasma electrolytic hardening were investigated. Electrolytic-plasma hardening of steel samples was carried out by surface quenching with rapid concentrated heating of the surface by plasma action and subsequent rapid cooling by heat removal from the depth of the sample by electrolyte jet. Plasma electrolytic hardening was carried out in the cathode mode in an electrolyte made from an aqueous solution containing 20 % sodium carbonate and 10 % carbamide. To study the structural-phase states of the modified layer, we used the method of transmission diffraction electron microscopy on thin foils. The study of steel samples was carried out before and after the plasma electrolytic hardening. Initially, the steel was a mixture of pearlite and ferrite grains. Surface hardening of 0.34C–1Cr–1Ni–1Mo–Fe ferrite-pearlite steel led to a change in the structural-phase state and the formation of a packet-lamellar martensite structure. It was found that PEH leads to distortion of the crystal lattice and the formation of long-range internal stresses, as well as to the release of small particles of cementite and carbide of M23C6 type, uniformly distributed throughout the volume of the material. Surface hardening led to the increase in all quantitative parameters of the fine structure (ρ, ρ ±, χ, σL, σd).

Structural-Phase State of UFG-Titanium Implanted with Aluminum Ions

2020 ◽  
Vol 303 ◽  
pp. 161-168
Author(s):  
Alisa V. Nikonenko ◽  
Natalya A. Popova ◽  
E.L. Nikonenko ◽  
M.P. Kalashnikov ◽  
I.A. Kurzina
Keyword(s):  
Grain Size ◽  
Yield Stress ◽  
Phase State ◽  
Structural Phase ◽  
Ion Source ◽  
Anisotropy Factor ◽  
Structural Phase State ◽  
Aluminum Ions ◽  
Average Grain Size ◽  
Before And After

Transmission electron microscopy investigations were carried out to study the structural-phase state of ultra-fine grain (UFG) titanium with the average grain size of ~0.2 μm, implanted with aluminum ions. Implantation was carried out on MEVVA-V.RU ion source at room temperature, exposure time of 5.25 h and ion implantation dosage of 1⋅1018 ion/cm2. UFG-titanium was obtained by a combined multiple uniaxial compaction with rolling in grooved rolls and further annealing at 573 К for 1h. The specimens were investigated before and after implantation at a distance of 70-100 nm from the specimen surface. Concentration profile of aluminum implanted with α-Ti was obtained. It was revealed that the thickness of implanted layer was 200 nm, while maximum aluminum concentration was 70 at.%. Implantation of aluminum into titanium has resulted in formation of the whole number of phases having various crystal lattices, like β-Ti, TiAl3, Ti3Al, TiC and TiO2. The areas of their localization, the sizes, distribution density and volume fractions were determined. Grain distribution functions by their sizes were built, and the average grain size was defined. The paper investigates the influence of implantation on the grain anisotropy factor. It was revealed that implantation leads to the decrease in the average transverse and longitudinal grain size of α-Ti and decrease in the anisotropy factor by three times. The yield stress and contributions of separate strengthening mechanisms before and after implantation were calculated. The implantation has resulted in increase in the yield stress by two times.

The Influence of Welding Mode on the Structural-Phase State of Steel 0.12С-18Cr-10Ni-1Ti-Fe at Welding by Modulated Current

2020 ◽  
Vol 303 ◽  
pp. 118-127
Author(s):  
A.N. Smirnov ◽  
Natalya A. Popova ◽  
E.L. Nikonenko ◽  
N.V. Ababkov ◽  
K.V. Knyazkov ◽  
...  
Keyword(s):  
Martensitic Transformation ◽  
Base Metal ◽  
Heat Affected Zone ◽  
Phase State ◽  
Dislocation Substructure ◽  
Structural Phase ◽  
Droplet Transfer ◽  
Structural Phase State ◽  
Fine Droplet ◽  
Thin Foils

Investigations conducted by transmission electron microscopy on thin foils were aimed at studying the structural-phase state of heat-affected zone of the welding joint performed by modulated current at two welding modes: coarse-droplet and fine-droplet transfer. Welding was conducted on the austenitic steel 0.12С-18Cr-10Ni-1Ti-Fe using the facility UDI-203. Welding modes were: Ii = 175 А (coarse-droplet transfer) and 140 А (fine-droplet transfer). Welding was performed on thin foils sized 200 × 15 × 4 mm3. Investigations were focused on heat-affected zone at the distance of 1 mm from the weld line towards the base metal – the base metal zone and at the distance of 0.5 mm towards the welded metal – the welded metal zone. The studies showed that in the state before welding the steel matrix presents γ-phase (austenite), which has face-centered cubic (fcc) crystal lattice. Morphologically the steel structure is given as grains where defect structure is presented by only network dislocation substructure, and grains where along with the dislocation substructure there are mechanical (or deformation) microtwins in the form of packages of one, two and three systems. It was established that welding of steel 0.12С-18Cr-10Ni-1Ti-Fe by modulated current with coarse-droplet transfer leads to martensitic transformation γ → ε only in the welded metal zone. At fine-droplet transfer welding leads to martensitic transformation γ → ε both in the base metal zone and in the welded metal zone. In the welded metal zone phase transformation γ → ε occurs more intensively. It was revealed that crystal lattice distortion in the whole heat-affected zone at welding by modulated current has only plastic nature, irrespective of the welding mode. Welding by modulated current with fine-droplet transfer leads to lower internal stresses in the whole heat-affected zone.

Formation of Fe2Si Wetting Coating on Si(001) 2×1 and Growth of a Stable Fe Nanolayer: AES and EELS Study

2020 ◽  
Vol 312 ◽  
pp. 9-14
Author(s):  
Nikolay I. Plusnin ◽  
Andrey M. Maslov ◽  
Vladimir M. Il’yashenko
Keyword(s):  
Electron Spectroscopy ◽  
Phase State ◽  
Structural Phase ◽  
Energy Losses ◽  
Two Dimensional ◽  
Auger Electrons ◽  
Structural Phase State ◽  
Before And After ◽  
The One

The structural-phase state of two-dimensional (d = 1 - 3 ML) coatings before and after annealing and that of Fe nanolayers (d = 4 - 10 ML) were investigated on Si (001)2×1 by electron spectroscopy methods of Auger-electrons and energy losses. The room (30 °С) and lowed (≤ 1250 °С) temperatures of the Si (001) substrate and Fe vapor, respectively, were used during Fe deposition. This study showed the following. An ordered two-dimensional 1×1 phase of Fe stable up to 600 °C and then a Fe2Si wetting coating stable at 250 °C form near the thickness 1 ML and 3 ML, respectively. Fe deposition on this Fe2Si coating leads to the one-after-another formation of the Fe3Si, the Si-in-Fe solution, and then a stable up to 250 °C Fe nanofilm with segregated Si.

Influence of composition on the structural-phase state, electrophysical and magnetotransport properties of alloy thin films based on Co and Cu

Vacuum ◽  
2021 ◽  
Vol 187 ◽  
pp. 110141
Author(s):  
I.O. Shpetnyi ◽  
I.Yu Protsenko ◽  
S.I. Vorobiov ◽  
V.I. Grebinaha ◽  
L. Satrapinskyy ◽  
...  
Keyword(s):  
Thin Films ◽  
Phase State ◽  
Structural Phase ◽  
Structural Phase State

scholarly journals Analysis of the Morpho-Geometrical Changes of the Root Canal System Produced by TF Adaptive vs. BioRace: A Micro-Computed Tomography Study

Materials ◽  
2021 ◽  
Vol 14 (3) ◽  
pp. 531
Author(s):  
Loai Alsofi ◽  
Muhannad Al Harbi ◽  
Martin Stauber ◽  
Khaled Balto
Keyword(s):  
Surface Area ◽  
Root Canal ◽  
Type I ◽  
Structure Model ◽  
Canal Surface ◽  
Canal System ◽  
Structure Model Index ◽  
Continuous Rotation ◽  
Before And After ◽  
Root Canal System

We aimed to analyze the morpho-geometric changes of the root canal system created by two rotary systems (TF Adaptive and BioRace) using micro-CT technology. Two concepts of rotary file system kinematics, continuous rotation and adaptive kinematics, were used in root canal preparation. Twenty mandibular molars (n = 20) were selected with the following criteria: the teeth have mesial roots with a single and continuous isthmus connecting the mesiobuccal and mesiolingual canals (Vertucci’s Type I configuration) and distal roots with independent canals. Teeth were scanned at a resolution of 14 μm. Canals were divided equally into two groups and then enlarged sequentially using the BioRace system and TF Adaptive system according to manufacturer protocol. Co-registered images, before and after preparation, were evaluated for morphometric measurements of canal surface area, volume, structure model index, thickness, straightening, and un-instrumented surface area. Before and after preparation, data were statistically analyzed using a paired sample t-test. After preparation, data were analyzed using an unpaired sample test. The preparation by both systems significantly changed canal surface area, volume, structure model index, and thickness in both systems. There were no significant differences between instrument types with respect to these parameters (p > 0.05). TF Adaptive was associated with less straightening (8% compared with 17% for BioRace in the mesial canal, p > 0.05). Both instrumentation systems produced canal preparations with adequate geometrical changes. BioRace straightened the mesial canals more than TF Adaptive.

Influence of ball milling duration on the morphology, features of the structural-phase state and microhardness of 3Ni-Al powder mixture

2021 ◽  
Author(s):  
Ivan A. Ditenberg ◽  
Denis A. Osipov ◽  
Michail A. Korchagin ◽  
Ivan V. Smirnov ◽  
Konstantin V. Grinyaev ◽  
...  
Keyword(s):  
Ball Milling ◽  
Powder Mixture ◽  
Phase State ◽  
Structural Phase ◽  
Structural Phase State ◽  
Milling Duration ◽  
Al Powder
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