UA110312C2 - Method of manufacturing bainite rail steel, rolling track pitch and device for implementation of it - Google Patents

Abstract

The invention relates to a rolling track, in particular rails for rail vehicles made of low-alloy steel, wherein the steel from which the rail head is made, on the section of the rolling track includes a ferrite fraction of 5-15% by volume, and a multiphase bainite structure consisting of upper and lower bainite particles.

Description

The invention relates to a running track, in particular a rail for rail vehicles, made of low-alloy steel.

In addition, the invention relates to a method of manufacturing a raceway from a hot-rolled section and a device for implementing the method.

Recently, the weight and speed of movement of goods transported by rail are constantly increasing in order to increase the efficiency of rail transport. Railway tracks are therefore subject to increased operating conditions and, as a result, must be of higher quality to withstand higher loads.

Certain problems associated with the use of concrete cause extensive wear, particularly of rails mounted on curved sections of track, and the appearance of material fatigue damage, which primarily occurs on the inner running face, which is the main point of contact between the rail and the wheels on the curved section of the track. As a result, a defect due to rolling fatigue (KSE) appears. Examples of surface defects due to rolling fatigue (CRF) are contact fatigue, delamination (split), subsidence (plastic deformation of the surface), inclined wave planes and corrugations. Such types of surface damage lead to a reduction in the life of the rail, an increase in noise and create operational obstacles. In addition, the increase in the occurrence of such defects will be accelerated by the ever-increasing loads from vehicles. A direct consequence of this development is the need to improve the quality of railway service. However, the growing need for quality maintenance comes into conflict with the ever-shrinking windows for maintenance. The higher the train density, the shorter the working time on the rails.

Although the above types of damage can be repaired in the early stages by grinding, for severe damage the rails must be replaced. Therefore, many attempts have recently been made to improve both the wear resistance of rails and their resistance to damage due to rolling fatigue, with the aim of increasing the life cycle (resource) of rails. Among other things, the problem was solved due to the introduction and use of bainitic rail steels.

Bainite is a structure that can be formed during heat treatment of carbon steel by isothermal transformation or continuous cooling. Bainite is formed at values of temperature and cooling rate in the range between those values, which are necessary for the formation of pearlite and martensite, respectively. In contrast to the above, in this case, with the formation of martensite flip - processes (overturning with a change in position) in the crystal lattice and diffusion processes are interconnected, providing at the same time different mechanisms of transformation. Due to its dependence on the cooling rate, carbon content, alloying elements and, therefore, due to the resulting temperature of formation, bainite acquires an uncharacteristic structure. Bainite, like pearlite, consists of ferrite and cementite (Rezs) phases, but it differs from pearlite in terms of shape, size and distribution. In principle, according to the shape, bainite is divided into two main structural groups, namely: upper bainite and lower bainite.

From the document AT-407057 B, a rail material is known, in which the structural transformation of austenite is clearly formed only in the range of lower bainite, giving the profiled mobile composition a hardness of at least 350 НВ, in particular, 450-600 НВ.

The main bainite structure can also be obtained due to a higher proportion of alloying components, for example, a higher chromium content, namely: from 2.2 to 3.0 95 by weight, as described in documents OE 1020060308915 A1 and OE 102006030816 A1. However, the presence of a high proportion of alloying components causes too high costs and the need to solve complex welding engineering problems. Document OE 202005009259 01 also describes the bainite high-strength part of the raceway made of high-alloy steel, containing, in particular, particles of high-alloy elements Mp, Zy and St. In such highly alloyed steels, the formation of bainite can be started in a simple way due to cooling at static parameters of atmospheric air. In contrast, low-alloy steels ensure the formation of bainite only during controlled cooling.

Accordingly, document OE-1533982, for example, describes a method of heat treatment of rails, in which the rail, which is still at rolling temperature, is lifted by a lifting device at the exit from the cage and immersed with the head of the rail down into a fluidized bed maintained at a constant temperature, where it is cooled, at thereby obtaining a crystalline bainite structure, moreover, the temperature in the fluidized bed is chosen in the range from 380 to 450 "C, and the rail is left in the fluidized bed for a period of time from 300 to 900 seconds, depending on the temperature of the latter.

From the document EP-612852 VI, another method of manufacturing high-strength rails from low-alloy steels having a bainite structure is known, which ensures the achievement of increased resistance to damage due to contact fatigue. The head of the rail is subjected to accelerated cooling from the austenite region (diagram) at a rate of 1-10 "C/s until the cooling interruption temperature of 500-300 "C is reached. After such rapid cooling, the rail head is further cooled to near room temperature using natural cooling with heat recovery or forced cooling at a rate of 1-40 °C/min.

Although, due to the above measures, the formation and spread of cracking on the rail head can be slowed down, they cannot be prevented.

Thus, the present invention is aimed at improving the section of the running track, in particular the rail, which must be made of low-alloy steel for reasons of cost and welding technique, and also at achieving a positive effect, which is that even with increased wheel loads, there should be no destruction, as a result of rolling contact fatigue, in particular, there is no cracking both on the inner edge of the rolling surface and on the running surface. In addition, wear resistance must be increased to ensure the product's service life, more than 30 years. At the same time, the section of the running track should be well welded and also exhibit other properties of materials similar to the properties of steels, which have already been successfully confirmed by the experience of railway construction, for example, similar electrical conductivity and a similar coefficient of thermal expansion.

In addition, this invention is aimed at creating a simple method of production, which is characterized by a reduction in the duration of the process (due to the cancellation of normalization phases), high reproducibility (repeatability) and high efficiency. The method should be suitable for the manufacture of long rails, having, for example, a length of more than 100 m, while the constant properties of the material should be ensured along the entire length of the rail.

In order to solve the technical problem, the invention, according to the first clause of the formula, provides a section of the raceway of the above type, which is improved in such a way that the steel of the rail head in the section of the raceway includes a ferrite fraction, which is 5-15 95 per volume and a multiphase bainite structure consisting of upper and lower bainite particles. Thanks to the combination of the ferrite structure with the bainite structure, it is ensured that excellent properties of elasticity (viscosity) and a fairly high

From strength. The ferrite structural component determines plasticity and prevents the possible formation of cracking in the form of cuts due to expansion in the material. The ferrite grain gives the overall structure a continuous network with intercalated (inserted) bainite. In this context, one should bear in mind the percolation threshold that must be reached to ensure such formation of adjacent regions (clusters). Preferably, the ferrite is acicular ferrite. Unlike the non-needle structure and unlike the pearlite structure, the needle structure is characterized by higher tensile strength and wear resistance. Acicular ferrite has a microstructure characterized by needle-shaped crystallites or grains, while these crystallites are unevenly oriented or present in a completely disoriented state, which positively affects the viscosity (elasticity) of steel. The disorientated arrangement of grains leads to mutual blocking of individual grains, which, in combination with multiphase bainite, effectively prevents the formation and propagation of cracking.

In particular, in this way it is ensured that the possible cracking formed on the surface in the form of cuts will not spread to a certain depth of the material, as it happens, for example, in the case of a pearlite structure. Thus, the section of the running track will only be subjected to wear and tear, so its service life can be accurately determined, and any additional observation regarding the formation of cracking can be avoided.

In addition, the presence of multiphase bainite, which includes upper and lower bainite particles, is essential. Upper bainite is formed in the upper temperature range of bainite formation and has a needle-like structure similar to the structure of martensite. At the indicated upper temperature range of bainite formation, favorable conditions for diffusion are formed, which allows carbon to diffuse to the grain boundaries of ferrite needles. Therefore, irregularly distributed and interrupted cementite crystals are formed. Due to the irregularity of the distribution, the structure often takes on the appearance of granules, so the upper bainite is sometimes also called granulated bainite. Lower bainite is formed during isothermal and continuous cooling in the lower temperature range of bainite formation. Due to the formation of ferrite, austenite is enriched with carbon, and during the subsequent cooling of the region, the austenite areas are transformed into ferrite, cementite, acicular bainite and martensite. Bainitization reduces internal stresses and increases product strength.

The mixing ratio between the lower and upper bainite can in principle vary widely depending on the respective requirements. The choice of mixing ratio will, in particular, determine the strength of the steel. In the context of this invention, it is preferred when the proportion of upper bainite is 5-75 95 by volume, in particular 20-60 95 by volume, and the proportion of lower bainite is 15-90 95 by volume, in particular 40-85 95 by volume.

The ferrite fraction is mainly 8-13 95 by volume.

The formation of carbide from austenite is a prerequisite for the complete transformation of bainite. Since carbides include a large amount of carbon, they are carbon absorbers when carbon is released from austenite. If the formation of carbide is prevented or slowed down, for example, by using silicon as an alloying element, the bulk of the austenite will escape the transformation process. Therefore, they will be either partially or completely present in the form of residual austenite after quenching to room temperature. The amount of residual austenite depends on how much the initial martensite temperature has decreased in the residual austenite. In the context of this invention, it is preferred that the fractions of austenite and/or martensite remain as low as possible. In this regard, the invention thus preferably provides a technical solution in accordance with which the steel of the rail head in the section of the raceway contains a proportion of residual martensite / austenite of less than 2 95 by volume.

As already mentioned above, low-alloy steels, according to the invention, are used in order to minimize costs and improve weldability. In general, low-alloy steel in the context of this invention mainly contains silicon, manganese and chromium, as well as the possible use of vanadium, molybdenum, phosphorus, sulfur and / or nickel as alloying components.

Steel, in the context of this invention, should be low-alloyed steel, if the proportion of any of the alloying components present in it does not exceed 1.5 95 by mass.

Especially good results can be achieved for low-alloy steel having the following reference composition, wt.9o: 0.4-0.55 (9; 0.3-0.6 with 0.9-1.4 My 0.3- 0.6 Si 0.1-0.3 M 0.05-0.20 Mo 0-0.02 P 0-0.02 Z 0-0.15 Mi

A particularly high suitability for highly loaded sections of the running track can preferably be ensured if the section of the running track has a tensile strength Kt higher than 1150 N / mm" in the area of the rail head. At the same time, the section of the running track has a hardness of

From above 340 NE in the area of the rail head.

According to the second independent clause of the formula, the invention provides a method of manufacturing the section of the rolling track described above, in which the section of the rolling track is made from a hot-rolled section, while the rail head from graded rolled steel is subjected to controlled cooling immediately upon exiting the cage in a state heated during rolling, at the same time, the above-mentioned regulated cooling process in the first stage includes accelerated cooling until the first temperature value is reached, which ensures the formation of ferrite, in the second stage, maintenance of the above-mentioned first temperature is ensured for the implementation of the ferrite formation process, in the third stage, further cooling is carried out within the temperature range, which ensures the formation of multiphase bainite until the second temperature value is reached, and in the fourth stage, the second value of the above temperature is maintained. Such adjustable cooling is carried out, preferably, by immersing at least the head of the rail in the cooling liquid, which is known in itself from the state of the art.

The first stage preferably starts at a temperature of 740-850 C, in particular, about 790 C, and preferably ends at a temperature of 450-525 "C. The cooling carried out in the first stage should be controlled in such a way as to achieve the provision of ferrite zones, then bainite, the formation of a "time-temperature-transformation" dependence graph, in which, in particular, there is no transformation at the pearlite stage. For this purpose, accelerated cooling at the first stage is preferably carried out at a cooling rate of 2-5 "C/b. Achieving the indicated cooling rate is preferably carried out in such a way that the section of the rolling track is completely immersed in the cooling liquid in the first stage.

At the second stage, the temperature is mainly maintained at 450-525"C, while the fraction of ferrite, in particular, the fraction of acicular ferrite, which is very important for consumer properties, is formed in the volume fraction of 5-15 95, in particular, 8-13 95, in particular, approximately 10 95. Temperature maintenance is preferably achieved by maintaining the section of the raceway in a position removed from the coolant in the second stage.

At the third stage, further controlled cooling is carried out for a specified limit of the fraction of ferrite, thereby causing the formation of a mixture of upper and lower bainite structures (multiphase bainite). The temperature range in which the formation of bainite takes place is mainly between 450-525 "C and 280-350 "C, that is, the head of the rail of the raceway section is cooled from 450-525 "7C to 280-350 "C in the phase of bainite formation. The specified third stage is preferably carried out within 550-100 s, in particular, approximately 70 s. In the phase of bainite formation, it is preferable to immerse the section of the raceway in the cooling liquid only with the head of the rail.

With further maintenance of the temperature in the raceway section, preferably in the range from 280-350 "С, in the fourth stage, the hardness of the raceway section is finally fixed as a function of the temperature state, at which it is necessary to avoid dropping the temperature below the temperature of the beginning of martensite formation (usually, about 280 С ), because too many martensitic brittle structural components must be formed in this temperature range. In the fourth stage, temperature maintenance is mainly ensured by cyclic immersion of the head, i.e. a section of the raceway is cyclically immersed in the coolant and removed from the coolant.

Since the temperature range of the formation of the bainite phase and the temperature of the beginning of martensite formation depend on the content of alloying elements in the corresponding steel and their respective percentages, the value of the first temperature and the value of the second temperature for the corresponding steel must be precisely determined in advance. During regulated cooling, the temperature of the rail is continuously measured, with the cooling and temperature maintenance operations starting and stopping, respectively, when the corresponding temperature thresholds are reached.

Considering the fact that the temperature of the rail surface can vary along the entire length of the track section, cooling is carried out evenly over the entire track section

From rolling, it mainly proceeds in such a way that the temperature indicators are determined at many measurement points distributed along the length of the section of the rolling track, and form the average temperature value, which is used to control the specified controlled cooling.

In the phase of bainite formation, austenite is most completely transformed into bainite. This happens at temperatures below the formation of pearlite until the temperature of the beginning of martensite formation is reached, both isothermally and during continuous cooling.

Due to the slow overturning of austenite, retreating from grain boundaries or crystal defects, highly carbon-saturated ferrite crystals with a cubic volume-centered crystal lattice are formed. Due to the high intensity of diffusion in the cubic volume-centered crystal lattice, carbon is deposited in the form of spherical or ellipsoidal cementite crystals within the ferrite grain. Carbon can also diffuse into the austenitic region and form carbide.

In the context of this invention, the cooling and temperature maintenance during the third and fourth stages are carried out in such a way as to form multiphase bainite. In the first sub-step, continuous cooling is carried out at a lower cooling rate than in the second sub-step, when the temperature is sharply reduced until the second temperature value is reached. In the first substage, first of all, the upper bainite is formed. After sharp cooling, the second temperature value is maintained in the fourth stage, during which lower bainite is formed. The length of time of maintaining the second temperature value in the fourth stage determines the level of formation of the lower bainite.

Upper bainite consists of acicular ferrite located in packets. Between individual ferrite needles, there are more or less continuous films of carbides extending parallel to the axis of the needle. The lower bainite, unlike the upper bainite, consists of ferrite plates, within which carbides are formed, located at an angle of 60" in relation to the axis of the needle.

During controlled cooling with a liquid coolant, the coolant goes through three phases of the quenching procedure. In the first phase, that is, the phase of the vapor film, the temperature on the surface of the rail head is so high that the temperature of the coolant quickly evaporates during the formation of a thin insulating vapor film (Leidenfrost effect (I eidepito5). This phase of the vapor film, in particular, largely depends on from the heat of vaporization of the coolant, the nature of the surface of the raceway area, such as scale, or the chemical composition and configuration of the cooling tank.In the second phase, i.e. the boiling phase, the coolant comes into direct contact with the hot surface of the rail head and immediately begins to boil, resulting in a higher cooling rate. The third phase, the convection phase, begins as soon as the surface temperature of the raceway area drops to the boiling point of the coolant. At this stage, the cooling rate essentially depends on the coolant flow rate.

During the controlled cooling presented in the claimed invention, the cooling liquid in the first stage exists mainly in the vapor film phase. Further, the process preferably proceeds in such a way that the cooling in the third stage is regulated in such a way as to force the coolant to first form a vapor film on the surface of the rail head, and then to ensure the boiling process on the indicated surface. Therefore, there is a transition from the vapor film phase to the boiling phase. The vapor film phase propagates along the entire length during the above-mentioned first sub-stage, in which the upper bainite is formed primarily. After reaching the boiling phase, the temperature drops sharply to the second temperature value, that is, mainly to 280-35076.

The transition from the vapor film phase to the boiling phase is usually relatively uncontrolled and spontaneous. Since the temperature of the rail is subject to certain production-related deviations along the entire length of the raceway section, a problem arises, the essence of which is that the transition from the vapor film phase to the boiling phase occurs at different times in the sections of the raceway of different lengths. This can lead to the formation of an uneven crystal structure and, therefore, to the formation of heterogeneous material properties along the entire length of the track section. In order to match the transition time from the vapor film phase to the boiling phase along the entire length of the rail, the preferred mode of implementation of the method provides that in the third stage, a gaseous medium to break the film, such as nitrogen, under pressure, is supplied to the head of the rail along the entire length of the rail. the length of the raceway section to break the vapor film along the entire length of the raceway section and cause the boiling phase.

This can, in particular, be done so that the condition of the coolant in the third stage is monitored along the entire length of the raceway section, and the gaseous medium having

To tear the film, it was applied under pressure to the head of the rail at the first appearance of signs of the boiling phase in the length zone of the section of the rolling track.

The gaseous medium, which should break the film, under pressure, is preferably supplied to the head of the rail in about 20-100 s, in particular, about 50 s, after the start of the third stage.

According to another independent clause of the formula of this invention, a device for carrying out the method described above is claimed, which contains a cooling tank corresponding to the length of the section of the running track and suitable for filling with a cooling liquid, a device for raising and lowering the section of the running track, in order to immerse the section of the running track in cooling tank and its removal from it, a device for measuring the temperature in the section of the running track, a means for generating a medium under pressure for injecting a medium under pressure into the cooling liquid, a means for regulating the temperature of the cooling liquid and a control device to which the resulting temperature measurement signals from a device for measuring temperature and which interacts with a device for raising and lowering, in order to control the operations of raising and lowering, with a means for regulating the temperature of the coolant, depending on the results of temperature measurements, and, in addition , with means for generating a pressurized environment.

In the preferred embodiment of the invention, sensors are provided for detecting the process of boiling of the cooling liquid on the surface of the rail head, the results of which measurements are fed to the control device for activating the means of generating the medium under pressure, depending on the sensor measurements. In particular, many sensors can be provided to detect the process of boiling of the cooling liquid on the surface of the rail head, and these sensors are distributed along the entire length of the cooling tank.

In a preferred embodiment of the invention, the measurement results of a plurality of sensors are sent to the control device, while the specified control device activates the means for generating a medium under pressure as soon as at least one sensor detects signs of boiling of the cooling liquid on the surface of the rail head.

The control device is preferably configured to provide the ability to perform controlled cooling, which includes at the first stage the acceleration of cooling until reaching the first temperature value that ensures the formation of ferrite, at the second stage - maintaining the above-mentioned value of the first temperature, which ensures the formation of ferrite, at the third stage stage - further cooling in the temperature range that ensures the formation of multiphase bainite, until reaching the second temperature value, and in the fourth stage - maintenance of the specified second temperature value.

The control device can, in particular, be set (configured) to reduce the temperature of the rail head in the first stage to the first temperature value of 450-525 7C at a cooling rate of 2-5" / s to maintain the temperature of the rail head in the second stage at the first temperature value, and reduce the temperature of the rail head in the third stage to the second temperature value of 280-350 "С, preferably within 50-100 s, in particular, about 70 s.

The control device is preferably set (configured) for the possibility of activating the means of generating the medium under pressure in the third stage.

In the following, the invention is described in more detail with the help of examples.

Low-alloy steel having the following reference composition was subjected to hot rolling to form a running rail with a standard rail profile, wt. 9o: 0.49 (9; 0.36 from 111 Mp 0.53 St 0.136 U 0.0085 Mo 0.02 P 0.02 Z 01 Mi

Immediately after leaving the cage, the rail, heated during rolling, was subjected to controlled cooling. The specified controlled cooling will be analyzed in detail below with reference to the graph of the dependence of the conversion process on the "time-temperature" relationship, presented in Fig. 1, while the line indicated by position 1 indicates the development of the cooling process. The cooling procedure was started at a temperature of 790 "С. At the first stage, the rail was immersed in a cooling bath with water along its entire length and across its entire cross-section, while the cooling rate was adjusted to 4 "C/s. After approximately 75 seconds, the temperature measuring device recorded a temperature of 490 "C on the surface of the rail head, and after reaching point 2, the rail was removed from the cooling bath to maintain the temperature for approximately 30 seconds, in order to ensure the conditions for the formation of acicular ferrite .When point 3 was reached, the rail was re-immersed in the cooling bath and cooled to point 4. At point 4, a nucleation of the beginning of cooling water boiling was detected on the surface of the rail head, and compressed air was applied to the rail head to break the vapor film covering the head. rail, and initiate the boiling phase along the entire length of the rail. The initiation of the boiling phase caused a sharp decrease in the temperature of the rail head. Such cooling was stopped when reaching

From a temperature of 315"C (point 5). Using cyclic immersion of the head, the indicated temperature was maintained for a certain time. The duration of the maintenance time is determined by the composition of the multiphase structure of bainite, which will become obvious from the following examples.

Example 1

In the first typical example of the implementation of the invention, low-alloy steel having the following reference composition was subjected to hot rolling to form a running rail with a standard rail profile: 0.49 (9; 0.36 z 111 Mp 0.53 St 0.136 U 0.0085 Mo 0.02 P 0.02 Z 01 Mi

Thanks to the controlled cooling described above, the following fine structure was obtained in the head of the rail: about 10 95 by volume of acicular ferrite, about 74 95 by volume of upper bainite, about 16 95 by volume of lower bainite, "1 95 by volume volume of martensite - residual austenite.

The thin structure is shown in fig. 2.

Due to the higher proportion of upper bainite, a lower hardness of the rail head was achieved than in the subsequent, second characteristic example of the implementation of the invention. The following material properties were measured.

Hardness: 347 HB

Tensile strength limit: 1162 MPa 0.2 95 yield point (plasticity): 977 MPa

Relative elongation at break: 14.4 95

Impact test with notch:

Test at 207 C: 110 J / sm

Test at -20"C: 95 J/cm

Crack growth: yes/aM (crack length increase in one fatigue cycle).

Test at DK-10 MPahmi: 8.9 (t/ssi

Test at DK-13.5 | MPahmi: 15.8 (t/Ssi,

Where (t/sos)| - m / gigacycle.

Durability:

Amsler's test (AM5IGG EK): 10 95 sliding (sliding), normal force 1200 N

Material wear: 1.72 mg/m?

Comparison of P260 with wear: 1.79 mg/m?

Crack resistance: 39 MPahm

Example 2

In the second typical implementation example, the same low-alloy steel as in example 1 was used to form a running rail with a standard rail profile by hot rolling. Controlled cooling was carried out similarly to that described in example 1, but the temperature in the fourth stage was maintained for a longer period of time than in example 1. The following fine structure was obtained in the head of the rail: about 10 95 by volume of acicular ferrite, about 15 95 by volume of upper bainite,

Co) about 75 95 by volume of lower bainite, "1 95 by volume of martensite - residual austenite.

The thin structure is shown in fig. 3.

The following material properties were measured.

Hardness: 405 HB

Tensile strength limit: 1387 MPa 0.2 95 yield strength (plasticity): 1144 MPa

Relative elongation at break: 12.6 95

Impact test with notch:

Test at -- 207 C: 100 J/cm-

Test at -20? C: 75 J / cm-

Crack growth: yes/aM (crack length increase in one fatigue cycle).

Test at DK-10 MPahmi: 9.5 |(t/СсI

Test at DK-13.5 | MPahmi: 16.5 (t/ssi,

Where (t/ss)| - m / gigacycle.

Durability:

Amsler's test (AM5IGG EK): 10 95 sliding (sliding), normal force 1200 N

Wear of material: 1.55 mg/m2

Comparison of K260 with wear: 1.79 mg/me

Crack resistance: 36 MPaum

Claims (29)

FORMULA OF THE INVENTION 1. The raceway section, in particular the rail for rail transport, is made of low-alloy steel, characterized in that the steel of the rail head in the raceway section includes a ferrite fraction of 5-15 95 by volume and a multiphase bainite structure that consists of upper and lower bainite particles. 2. The section of the raceway according to claim 1, which differs in that the fraction of the upper bainite is 5-75 95 by volume, in particular 20-60 95 by volume, and the fraction of the lower bainite is 15-90 95 by volume , in particular 40-85 95 by volume. 3. The section of the rolling track according to claim 1 or 2, which differs in that the fraction of ferrite is 8-13 95 by volume. 4. The section of the raceway according to any of claims 1-3, which is characterized by the fact that the ferrite is acicular ferrite. 5. The section of the raceway according to claim 4, which is characterized by the fact that multiphase bainite is intercalated in the structure of acicular ferrite. 6. The raceway section according to any one of claims 1-5, characterized in that the steel of the rail head of the raceway section contains a residual fraction of martensite/austenite that is 2 Cho by volume. 7. A raceway section according to any one of claims 1-6, characterized in that the low-alloy steel contains silicon, manganese and chromium, and optionally vanadium, molybdenum, phosphorus, sulfur and/or nickel as alloying components. 8. The section of the rolling track according to claim 7, which is characterized by the fact that the proportion of none of the alloying components present does not exceed 1.5 95 by mass. 9. The section of the rolling track according to any of claims 1-8, which is characterized by the fact that low-alloy steel is used, having the following reference composition, wt. 90: 0.4-0.55 C, 0.3-0.6 51, 0.9-1.4 Mp, 0.3-0.6 Sg, 01-03 M, 0.05-0.20 Mo, 0-0.02 P, 0-0.02 5, 0-0.15 Mi. 10. A track section according to any of claims 1-9, which is characterized by the fact that the specified section of the track has a tensile strength Kt higher than 1150 N/mm: in the area of the rail head. 11. The section of the rolling track according to any of claims 1-10, which is characterized by the fact that the specified section of the rolling track has a hardness higher than 340 HB in the area of the rail head. 12. The method of manufacturing a track section according to any of claims 1-11, from a hot-rolled section, which is characterized by the fact that the rail head made of graded rolled steel is subjected to controlled cooling immediately upon exiting the cage in a state heated during rolling, while the specified above, the controlled cooling process at the first stage includes accelerated cooling at a cooling rate of 2-5 "C/s, starting from a temperature of 740-850 C, in particular about 790 "C, until reaching the first temperature value of 450-525 C, which ensures the formation of ferrite, on in the second stage, the above-mentioned first temperature is maintained for the process of ferrite formation, in the third stage, further cooling is carried out within the temperature range, which ensures the formation of multiphase bainite until the second temperature value of 280-350 "C is reached, while cooling is continued for a period of time of 50- 100 s, in particular 70 s, and at the fourth stage they support the second value of the specified higher temperature. 13. The method according to claim 12, which is characterized by the fact that the temperature indicators are determined at many measurement points distributed along the length of the raceway section, and form the average temperature value, which is used to control the specified controlled cooling. 14. The method according to claim 12 or 13, which is characterized by the fact that the controlled cooling is carried out by immersing at least the head of the rail in a cooling liquid. 15. The method according to any one of claims 12-14, characterized in that the cooling in the third stage is controlled in such a way as to force the cooling liquid to first form a film of vapor on the surface of the rail head and then to boil on said surface. 16. The method according to claim 15, which is characterized by the fact that in the third stage, a gaseous medium that should break the film, such as nitrogen, is supplied under pressure to the head of the rail along the entire length of the raceway section to break the vapor film along the entire length of the raceway section and cause the boiling phase. 17. The method according to claim 16, which differs in that the state of the coolant in the third stage is monitored along the entire length of the section of the rolling track, and the gaseous medium, which should break the film, is fed under pressure to the head of the rail at the first appearance of signs of the boiling phase in the extension zone taxiway sections. 18. The method according to claim 16 or 17, which is characterized by the fact that the gaseous medium, which should break the film, is supplied under pressure to the head of the rail for almost 20-100 s, in particular about 50 s, after the start of the third stage. 19. The method according to any one of claims 12-18, which is characterized by the fact that the section of the rolling track is completely immersed in the cooling liquid in the first stage. 20. The method according to any one of claims 12-19, which is characterized in that the section of the rolling track is kept in a state of removal from the cooling liquid in the second stage. 21. The method according to any one of claims 12-20, which is characterized by the fact that the section of the raceway is simply immersed in the cooling liquid with the head of the rail in the third stage. 22. The method according to any one of claims 12-21, which is characterized in that the section of the raceway is cyclically immersed in the cooling liquid and removed from the cooling liquid in the fourth stage. 23. A device for carrying out the method according to any of claims 12-22, containing a cooling tank corresponding to the length of the running track section and suitable for filling with a cooling liquid, a device for raising and lowering the running track section for immersing the running track section in the cooling tank and removing it from it, a device for measuring the temperature of the running track area, a means for generating a medium under pressure for injecting a medium under pressure into the cooling liquid, a means for regulating the temperature of the cooling liquid and a control device to which the resulting temperature measurement signals from the temperature measuring device are received and which interacts with the lifting and lowering device to control the lifting and lowering operations, with the means for adjusting the temperature of the coolant, depending on the results of the temperature measurements, and, in addition, with the means for generating the pressurized medium. 24. The device according to claim 23, which is characterized by the fact that sensors are provided for detecting the process of boiling of the cooling liquid on the surface of the rail head, the results of which measurements are fed to the control device for activating the means of generating the medium under pressure, depending on the results of the sensor measurements. 25. The device according to claim 24, which is characterized by the fact that a number of sensors are provided for detecting the process of boiling of the cooling liquid on the surface of the rail head, and the indicated sensors Zo are distributed along the entire length of the cooling tank. 26. The device according to any one of claims 23-25, characterized in that the measurement results of a plurality of sensors are fed to a control device, while said control device activates the means for generating a medium under pressure as soon as at least one sensor detects signs of boiling of the coolant on the surface of the rail head. 27. The device according to any one of claims 23-26, characterized in that the control device is configured to provide the ability to perform controlled cooling, which includes, in the first stage, accelerated cooling until reaching a first temperature value that ensures the formation of ferrite, in the second stage - maintenance of the above-mentioned first temperature value, which ensures the formation of ferrite, in the third stage - further cooling in the temperature range that ensures the formation of multiphase bainite, until the second temperature value is reached, and in the fourth stage - maintenance of the specified second temperature value. 28. The device according to claim 27, which is characterized in that the control device is configured to reduce the temperature of the rail head in the first stage to the first temperature value of 450-525 "C at a cooling rate of 2-5 "C/s, to maintain the temperature of the rail head at in the second stage at the first temperature value, as well as to reduce the temperature of the rail head in the third stage to the second temperature value of 280-350 "С, preferably within 50-100 s, in particular about 70 s. 29. The device according to claim 27 or 28, characterized in that the control device is configured to activate the means for generating the pressurized environment in the third stage. ж B Ж х Я Ko і Z KZ KU х Ж і х U dos y -e Mena "5 ki stva dok sk ms х ZU y U "Z ; ke Za X SCHE j I as i sny E z ; KU KE, y odhutryuyuyuutnesttoteotnnnnntynya not z NI VN v z o vymy iz U y I Ben s Ten J zh KZ E m kov h Z h as sodi y rya - y y 3 Z zhk as Her still their ss - Z s gu du reni h x y. 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