Study of heat deformation influence in surface strain hardening of steel by thermofriction processing

Volkov, Оleg

doi:10.15587/1729-4061.2016.65458

Cited by 8 publications

(10 citation statements)

References 5 publications

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“…Structural changes that occur when the samples are heated after their TFH showed that there is a relative stability of the white surface layer. In all samples, after heating, three characteristic zones are preserved (hardening, thermаl softening, base metal, which were considered in previous studies, with the initial microhardness of the white surface layer 18.0 GPa [12].…”

Section: Resultsmentioning

confidence: 99%

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Investigation of the Transformation of the Structure and Properties of Heredity of Thermofrictional Hardening of Steel Under Conditions of Elevated Temperatures

Volkov

Pogrebnoy

Subbotinа

et al. 2021

METAL 2021 Conference Proeedings

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Thermofriction hardening of steels is a modern technology for extended use in the production of various parts, the surfaces of which require increased wear resistance. The presented research continues the work of the authors on the study of the transformation and properties of metal structures that have received frictional processing; identification of physical mechanisms of steel hardening and the formation of ideas about residual manifestations and support of the strength heredity of intense frictional contact in the subsequent life cycle of the part at the final operations of its shaping and operation under conditions of thermophysical loading similar to tempering. This study examines the behavior of surfaces hardened by thermofrictional treatment under conditions of subsequent operational thermal loading, which is simulated by heating to elevated temperatures (up to 600 °C) and holding steel at these temperatures for up to one and a half hours. Metallographic and durametric studies have been carried out on cross-sectional sections of 65G steel samples. The microhardness in the near-surface layer decreases the more, the higher the heating and the time of testing with an elevated temperature. At the same time, the surface of steel that has previously undergone thermofrictional hardening is much harder than its base in the entire range of experimental conditions. This indicates the prospects of thermofriction hardening for steel products operating under conditions of increased thermal loads, and stimulates further research in this direction.

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Section: Resultsmentioning

confidence: 99%

“…This can contribute to an increase in the economic effect, both in production and in the use of various products. In this regard [12], the use of thermo-friction hardening (TFH) is economically attractive in obtaining steel products with high hardness and, accordingly, the expected wear resistance of the surface.…”

Section: Introductionmentioning

confidence: 99%

Investigation of the Transformation of the Structure and Properties of Heredity of Thermofrictional Hardening of Steel Under Conditions of Elevated Temperatures

Volkov

Pogrebnoy

Subbotinа

et al. 2021

METAL 2021 Conference Proeedings

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“…Такий підхід може бути реалізований через використання різноманітних методів впливу на структурний стан поверхні виробів. Застосування, наприклад, технології ТФЗ [1,2] або інших методів зміцнення поверхні цілком можливе для вирішення подібних завдань. Однак доцільність застосування методів оброблення визначається можливістю досягнення необхідних властивостей одночасно з мінімізацією витрат та дотриманням вимог щодо кожного конкретного об'єкта зміцнення.…”

Section: вступunclassified

“…This is more profitable economically and can be realized by using different methods of influencing the structural condition of the products' surface. The use of, for example, TFH technology [1,2] or other methods of surface strengthening is possible to solve such problems. Goal.…”

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confidence: 99%

Developing a technological complex for restoring the properties of rolled rolls reduced in the process of grinding

Volkov¹

2022

Bulletin of KhNAHU

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Problem. The problem of increasing the resource of equipment for rolling production is on time. Rolling mills are a piece of equipment for rolling objects made of metals and alloys. They work in difficult operating conditions: at considerable loading, friction and the raised temperatures. As a result, there is a rapid wear of their work surfaces, which leads to defects. Due to the predominantly high cost of rolled rolls, it is better to restore them than to replace with new ones. This is more profitable economically and can be realized by using different methods of influencing the structural condition of the products’ surface. The use of, for example, TFH technology [1,2] or other methods of surface strengthening is possible to solve such problems. Goal. The purpose of the work is to develop a technological complex to restore the properties of rolled rolls, which were reduced in the process of grinding. The subject of the research are the samples in the form of rolled rolls, which are made of 40X steel. To achieve this goal, heat treatment of natural samples was carried out in different modes. Metallographic analysis and measurement of hardness of natural samples after their heat treatment in different modes was made. The optimal mode was selected, which provided the necessary properties. Heat treatment of rolled rolls in need of restoration was carried out according to this mode. Methodology. Two heat treatment modes were used to restore the required hardness of the rolling rolls hardening with heating to 860ºC and cooling in water; hardening with heating to 860ºC and cooling in 10% aqueous NaCl salt solution. Results. The cooling properties of the saline solution are higher than those of water. This ensured greater completeness of the martensitic transformation and the formation of a fine-needle martensitic structure with a small amount of Cr carbides. Therefore, a technological complex for restoring the properties of rolled rolls, which were reduced during grinding, was proposed. It consists of quenching from a temperature of 860°C with cooling in 10% aqueous solution of NaCl salt. After hardening it is necessary to carry out low-temperature release at a temperature of 180ºC for 2 hours with accelerated cooling.

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“…Accordingly, it can be considered as one of the main factors in the implementation of a number of processes that involve the use of friction. For example, technologies such as thermofriction cutting (TFC), thermofriction machining (TFM) [1], thermofriction strengthening (TFS) [2], additional thermofriction strengthening (ATFS) [3], or thermofriction welding (TFW) are seemingly dissimilar, but have an important common component -friction. In this case, friction is the driving force that creates the conditions for obtaining the expected result for each specific technological process.…”

Section: Introductionmentioning

confidence: 99%

Selection and Application of the Optimal Surface Engineering Method to Restore the Properties of Rolling Equipment Elements that Have Been Reduced Due to Violations of Surface Grinding Technology

Volkov,

Subbotina,

Kraevska

et al. 2023

SSP

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The methods of influence on the material using different energy sources are considered. The role of friction in several technological processes is emphasized. The technological process of heat treatment is proposed, which allowed to restore the properties of rolled rolls that were lost due to incorrect grinding conditions. Application of the proposed technological process has shown that: 40X steel can be hardened to martensite in oil, water, and in a 10 % aqueous solution of NaCI salt, but with different results (i); the most effective hardening mode for 40X steel rolls is quenching with cooling in a 10 % aqueous solution of NaCI salt and subsequent high-temperature tempering, which is necessary to remove dangerous residual stresses (ii); the structure of the surface working layer of 40X steel rolls, after the selected optimal heat treatment regime, consists of fine-needle martensite and a small amount of Cr carbides (iii); closer to the core of the rolls, in addition to martensite, there are areas of troostite-bainite structure (iv); the resulting structure of the rolled rolls is capable of ensuring their efficient and long-term operation, but under optimal conditions, when the rolls' heating temperatures do not exceed 200 °C, and the proposed temperature conditions are recommended for both operation and routine maintenance associated with periodic restorative grinding of the working surfaces of the rolled rolls (v).

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Study of heat deformation influence in surface strain hardening of steel by thermofriction processing

Cited by 8 publications

References 5 publications

Investigation of the Transformation of the Structure and Properties of Heredity of Thermofrictional Hardening of Steel Under Conditions of Elevated Temperatures

Investigation of the Transformation of the Structure and Properties of Heredity of Thermofrictional Hardening of Steel Under Conditions of Elevated Temperatures

Developing a technological complex for restoring the properties of rolled rolls reduced in the process of grinding

Selection and Application of the Optimal Surface Engineering Method to Restore the Properties of Rolling Equipment Elements that Have Been Reduced Due to Violations of Surface Grinding Technology

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