scholarly journals FORMATION OF NANOCRYSTAL STATE IN DETAILS OF CARBON STRUCURAL STEELS

2018 ◽  
pp. 113-118
Author(s):  
A. A. Andrushevich ◽  
G. I. Aniskovich ◽  
P L. Kantor ◽  
D. V. Kuchuk
Keyword(s):  
Experimental Data ◽  
Heat Treatment ◽  
Mechanical Characteristics ◽  
Structural Steels ◽  
Carbon Steels ◽  
Agricultural Machinery ◽  
Working Bodies

The conditions of formation of the nanocrystal state of the structure in carbon steels are considered in the article. The methods of research and experimental data on the microstructural structure of the strengthened parts of the working bodies of agricultural machinery made from carbon steels of the lowered hardenability are given. It is shown that pulsed quenching and low tempering provides of steel products with fragmented nanocrystal structure of the martensite. Fragmentation of martensite grains in carbon structural steels during heat treatment of parts significantly increases their mechanical characteristics.

Transition in iron and carbon steels at ~ 450 ºC

2021 ◽  
pp. 190-200
Author(s):  
К.Ю. Шахназаров ◽  
А.В. Михайлов ◽  
Д.В. Цуканов
Keyword(s):  
Experimental Data ◽  
Heat Treatment ◽  
Temperature Interval ◽  
Pure Iron ◽  
Carbon Steels ◽  
X Ray ◽  
Iron Platinum ◽  
Steel Properties

Вокруг интервала температур 400-500 °С сложилась любопытная ситуация. М.В. Белоус с соавторами в своей монографии «Превращение при отпуске стали» его просто не замечают в классификации четырех превращений при отпуске, хотя еще в 1925 г. П. Обергоффер, основываясь на минимуме при 400-500 °С термоЭДС пары железо-платина, писал: «Имеем ли мы здесь дело с дальнейшим превращениями в чистом железе, должны показать новые подробные исследования». В настоящей работе на основании анализа многочисленных литературных данных, а также собственных экспериментальных (металлографического исследования, рентгеноструктурного анализа, сопротивления «горячей» осадке на образцах из практически чистого железа (0,008% С)) сделана попытка обосновать превращение в железе при ~ 450 ºС. Признание превращения при данной температуре дает возможность прогнозирования аномалий свойств сталей (производного железа) на том или ином этапе термической обработки. There is a curious situation around the temperature interval of 400-500 °C. M.V. Belous and co-authors in their monograph «Transformation during tempering of steel» simply do not notice it in the classification of the four transformations during tempering, although back in 1925. P. Oberhoffer, based on a minimum at 400-500 °C of the thermo-EDC of iron-platinum pair, wrote: «Whether we are dealing here with further transformations in pure iron, should show new detailed research». In the present work based on the analysis of numerous literature data and our own experimental data (metallographic research, X-ray analysis, resistance of «hot» precipitation on practically pure iron samples (0.008% C)) we have made an attempt to prove the iron transformation at ~ 450 ºC. The recognition of transformation at this temperature makes it possible to predict anomalies of steel properties (iron derivatives) at a certain stage of heat treatment.

INCREASING THE WEAR RESISTANCE OF THE WORKING BODIES OF AGRICULTURAL MACHINES BY THE HDTV METHOD WITH ADDING POWDER OF THE EED METHOD

2020 ◽  
Vol 4 (141) ◽  
pp. 123-131
Author(s):  
IL’YA ROMANOV ◽  
Keyword(s):  
Wear Resistance ◽  
Abrasive Wear ◽  
High Frequency ◽  
Machine Building ◽  
Abrasive Wear Resistance ◽  
Research Purpose ◽  
Powder Materials ◽  
Agricultural Machinery ◽  
Resource Saving ◽  
Working Bodies

The development of energy and resource-saving methods and technologies for strengthening and restoring the working bodies of agricultural machinery will increase their abrasive wear resistance and durability by using materials from machine-building waste and reduce the cost by 10-30 percent without reducing operational characteristics. (Research purpose) The research purpose is in increasing the abrasive wear resistance and durability of cultivator legs by surfacing powder materials obtained by electroerosive dispersion from solid alloy waste by high-frequency currents. (Materials and methods) Authors obtained a powder for research on their own experimental installations of the CCP "Nano-Center" of electroerosive dispersion from waste of sintered hard alloys of the T15K6 brand. The microhardness of powders and coatings on microshifts was measured using the PMT-3 device, and the hardness of coatings with the KMT-1 microhardometer was measured using the Rockwell method according to GOST 9013-59. The microwave-40AV installation was used to assess the wear resistance of materials of working bodies of tillage machines. (Results and discussion) In the course of laboratory wear tests the relative wear resistance of samples hardened by high-frequency surfacing currents significantly exceeds the wear resistance of non-hardened samples made OF 65g steel, accepted as the reference standard. (Conclusions) Based on the results of experimental studies, the article proposes a new resource-saving technological process for strengthening the working bodies of agricultural machinery through the use of materials from machine-building waste, which allows increasing the abrasive wear resistance of working bodies by 1.5-2 times due to the use of tungsten-containing materials.

Viability of turbine blade material with a long service life

2019 ◽  
pp. 28-35
Author(s):  
O. B. Berdnik ◽  
I. N. Tsareva ◽  
M. K. Chegurov
Keyword(s):  
Heat Treatment ◽  
Service Life ◽  
Yield Strength ◽  
Mechanical Characteristics ◽  
Operating Time ◽  
Structural Features ◽  
Operating Conditions ◽  
Standard Methods ◽  
Experimental Values ◽  
Plasticity Coefficient

This article deals with structural features and characteristic changes that affect the mechanical characteristics after different service life in real conditions using the example of the blades of the 4th stage of turbine GTE-45-3 with an operating time of 13,000 to 100,000 hours. To study the change in the state of the material under different operating conditions, determine the degree of influence of heat treatment on the regeneration of the microstructure, and restore the mechanical characteristics of the alloy after different periods of operation, non-standard methods were used: relaxation tests on miniature samples to determine the physical yield strength and microplasticity limit and quantitative evaluation of the plasticity coefficient of the material from experimental values of hardness, which allow us to identify the changes occurring in the microvolumes of the material and predict the performance of the product as a whole.

Development of Heat Treatment Mode with Quenching in Different Quenching Environments for the Casing Pipe in Order to Obtain the Required Mechanical Properties

2020 ◽  
Vol 836 ◽  
pp. 41-45
Author(s):  
S.N. Dzhabbarov ◽  
E.I. Pryakhin
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Mechanical Characteristics ◽  
Oil And Gas ◽  
Oil And Gas Industry ◽  
Treatment Mode ◽  
Gas Industry ◽  
Heat Treatment Mode ◽  
Optimal Technology ◽  
Casing Pipe

Development of an optimal technology of heat treatment for blanks of the casing pipe made of steel 40H (GOST 4543) is used in the oil and gas industry for casing. It is accompanied by quenching in various environments to ensure guaranteed obtainment of the required mechanical characteristics. These characteristics are specified in GOST 632-80 and met in order to improve the properties of the 40H steel.

Diffusion Coefficients of Interest for the Simulation of Heat Treatment in Rare-Earth Transition Metal Magnets

2012 ◽  
Vol 727-728 ◽  
pp. 163-168 ◽  
Author(s):  
Marcos Flavio de Campos
Keyword(s):  
Experimental Data ◽  
Heat Treatment ◽  
Activation Energy ◽  
Rare Earth ◽  
Transition Metal ◽  
Impurity Atom ◽  
Diffusion Coefficients ◽  
Arrhenius Equation ◽  
Atom Diffusion ◽  
Essential Input

In the case of the modeling of sintering and heat treatments, the diffusion coefficients are an essential input. However, experimental data in the literature about diffusion coefficients for rare-earth transition metal intermetallics is scarce. In this study, the available data concerning diffusion coefficients relevant for rare-earth transition metal magnets are reviewed and commented. Some empirical rules are discussed, for example the activation energy is affected by the size of the diffusing impurity atom. Diffusion coefficients for Dy, Nd and Fe into Nd2Fe14B are given according an Arrhenius equation D=D0exp (-Q/RT). For Dy diffusion into Nd2Fe14B, Q 315 kJ/mol and D08 . 10-4m2/s.

scholarly journals High temperatures during microsporogenesis fatally shorten pollen lifespan

2021 ◽  
Author(s):  
Maurizio Iovane ◽  
Giovanna Aronne
Keyword(s):  
Experimental Data ◽  
Heat Treatment ◽  
Heat Stress ◽  
High Temperature ◽  
Male Gametophyte ◽  
Crop Productivity ◽  
Anther Dehiscence ◽  
Optimal Temperature ◽  
Drastic Reduction ◽  
Crop Species

AbstractMany crop species are cultivated to produce seeds and/or fruits and therefore need reproductive success to occur. Previous studies proved that high temperature on mature pollen at anther dehiscence reduce viability and germinability therefore decreasing crop productivity. We hypothesized that high temperature might affect pollen functionality even if the heat treatment is exerted only during the microsporogenesis. Experimental data on Solanum lycopersicum ‘Micro-Tom’ confirmed our hypothesis. Microsporogenesis successfully occurred at both high (30 °C) and optimal (22 °C) temperature. After the anthesis, viability and germinability of the pollen developed at optimal temperature gradually decreased and the reduction was slightly higher when pollen was incubated at 30 °C. Conversely, temperature effect was eagerly enhanced in pollen developed at high temperature. In this case, a drastic reduction of viability and a drop-off to zero of germinability occurred not only when pollen was incubated at 30 °C but also at 22 °C. Further ontogenetic analyses disclosed that high temperature significantly speeded-up the microsporogenesis and the early microgametogenesis (from vacuolated stage to bi-cellular pollen); therefore, gametophytes result already senescent at flower anthesis. Our work contributes to unravel the effects of heat stress on pollen revealing that high temperature conditions during microsporogenesis prime a fatal shortening of the male gametophyte lifespan.

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