JP2000219939A - Pearlitic rail with excellent wear resistance and surface damage resistance - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a high strength rail improved in wear resistance and surface damaging resistance required for heavy load railways by allowing it to have a compsn. contg. specified amounts of C, Si, Mn or the like and allowing at least a part thereof to have a pearlitic structure in which the value of 0.2% proof stress and total elongation is controlled to the specified one. SOLUTION: This steel rail is the one having a compsn. contg., by weight, >0.85 to 1.20% C, preferably contg. 0.10 to 1.00% Si and 0.10 to 1.50% Mn, moreover contg., at need, one or more kinds among 0.05 to 1.00% Cr, 0.01 to 0.20% Mo, 0.05 to 0.50% Cu, 0.05 to 1.00% Ni, 0.01 to 0.50% V, 0.002 to 0.050% Nb, 0.0001 to 0.0050% B, 0.0050 to 0.0300% Ti, 0.0010 to 0.0100% Mg, 0.0010 to 0.0150% Ca and 0.10 to 2.00% Co, and the balance iron with inevitable impurities, in which at least a part shows a pearlitic structure. In this pearlitic structure, 0.2% proof stress is controlled to 600 to 1200 MPa, and total elongation value is controlled to 7 to 12%.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pearlitic rail having improved abrasion resistance and surface damage resistance required for rails of heavy load railways.

[0002]

2. Description of the Related Art Overseas heavy-load railways have been designed to increase the speed of trains and increase the weight of trains as means for increasing the efficiency of rail transportation. Such an increase in the efficiency of rail transportation implies a severer use environment for rails, and further improvements in rail materials have been required. Specifically, wear on the GC (gauge corner) and head sides of the rails laid in the curved section sharply increases, and this has become a problem in terms of the service life of the rails. Was.

However, with the recent progress in heat treatment technology for increasing the strength, a high-strength (high-hardness) rail having a fine pearlite structure using eutectoid carbon steel as shown below has been invented. The rail life of the section has been dramatically improved. Heat treatment rail for ultra-high load with sorbite head or fine pearlite head (Japanese Patent Publication No. 54-2549)
No. 0). After the end of rolling or after reheating the rail head from the austenitic zone temperature to 850-500 ° C, 1-4 ° C / sec.
Method for manufacturing high-strength rails of 130 kgf / mm ² or more, accelerated by cooling (Patent No. 1597914). The features of these rails are high-strength rails exhibiting a fine pearlite structure by eutectoid carbon-containing steel (carbon content: 0.7 to 0.8%),
The purpose was to reduce the lamellar spacing in the pearlite structure and improve the wear resistance.

[0004] However, in recent years, heavy load railways overseas have been strongly promoting the loading of cargo in order to further increase the efficiency of rail transportation, and particularly in the case of sharply curved rails, using the rails developed above. However, the wear resistance of the GC section and the head side cannot be sufficiently ensured, and the reduction of the rail life due to the wear has become a problem. Against this background, the development of rails having wear resistance higher than that of the current high-strength eutectoid carbon steel rails has been required.

[0005] In order to solve these problems, the present inventors have developed the following rails. Using hypereutectoid steel (C: more than 0.85 to 1.20%),
A rail with excellent wear resistance in which the density of cementite in the lamella in the pearlite structure is increased (Japanese Patent Laid-Open No. 8-14406)
No. 1) Using hypereutectoid steel (C: more than 0.85 to 1.20%),
Rails with increased cementite density in lamellae in the pearlite structure, and at the same time, with controlled hardness and excellent wear resistance (JP-A-8-246100)

The features of these rails are that the carbon content of the steel is increased, the density of the highly wear-resistant semetite phase in the pearlite lamella is increased, and the hardness of the pearlite structure is controlled by controlling the hardness. Was to improve the properties. However, although rails with a pearlite structure using these hypereutectoid steels can improve wear resistance, rails laid in curved sections are subject to repeated contact with wheels, resulting in lower contact surface pressure and tangential force. Large rail head G.
Occurrence of surface damage such as creaking and flaking has been seen in the C. part and the head side part, and measures for these damages have been required.

Accordingly, the present inventors have studied a method for improving the wear resistance of rail steel and at the same time, preventing such surface damage. First, the present inventors elucidated the mechanism of these surface damages occurring in hypereutectoid pearlite steel. As a result, the G.I. C. It was found that a large plastic deformation zone was formed immediately below the rolling surface in the part and the head side part, and that cracks occurred along the plastic deformation zone (metal flow). Therefore, the present inventors investigated the relationship between the formation of these plastic deformation bands and the mechanical properties of the material in order to prevent the formation of these plastic deformation bands and the damage caused by the cracks. As a result, the formation of the plastic deformation zone, which is the source of surface damage, has a good correlation with the 0.2% proof stress of steel, and when the 0.2% proof stress is within a certain range, this plastic deformation region becomes smaller, It has been found that the occurrence of surface crack damage such as creaking and flaking is significantly suppressed.

Further, the present inventors have investigated the relationship between the magnitude of surface damage such as creaking and flaking generated from these plastic deformation regions and the mechanical properties of the material. As a result, the magnitude of these surface damages has a good correlation with the total elongation of the steel, and when the total elongation value is within a certain range, the length of the cracks due to the surface damage becomes smaller, and creaking cracks and flaking occur. It was found that the development of surface damage was significantly suppressed.

[0009] From the above results, the present inventors increased the carbon content of the steel in order to improve the abrasion resistance of the rail steel and at the same time prevent the occurrence of such surface damage, thereby increasing the resistance of the steel in the pearlite lamella. By increasing the density of the cermetite phase, which has excellent wear properties, at the same time, keeping the 0.2% proof stress within a certain range and further increasing the total elongation value within a certain range, the wear resistance is improved, and at the same time, creaking It has been found that the occurrence of surface damage such as cracking and flaking, and furthermore, its progress is significantly suppressed.

[0010] That is, an object of the present invention is to provide a high-strength rail with improved wear resistance and surface damage resistance required for heavy-load railways.

[0011]

SUMMARY OF THE INVENTION The present invention achieves the above object, and its gist is as follows: (1) By weight%, C: more than 0.85% to 1.20% or less. Containing, if necessary, Si: 0.10 to 0.10
A steel rail containing 1.00% and Mn: 0.10 to 1.50%, at least a part of which exhibits a pearlite structure, wherein the pearlite structure has a 0.2% proof stress of 600 to 12.
A pearlite-type rail excellent in wear resistance and surface damage resistance, which is characterized by being 00 MPa. (2) In weight%, C: more than 0.85% to 1.20% or less, Si: 0.10 to 1.00%, Mn: 0.10 to 0.10%
1.50%, Cr: 0.05 to 1.00%, Mo: 0.01 to 0.20%, Cu: 0.05 to 0.50%, Ni: 0.05 to 1.00%, V: 0.01 to 0.50%, Nb: 0.002 to 0.050%, B: 0.0001 to 0.0050%, Ti: 0.0050 to 0.0300%, Mg : 0.0010 to 0.0100%, Ca: 0.0010 to 0.0150%, Co: 0.10 to 2.00%, and the balance consists of iron and inevitable impurities. A steel rail having a pearlite structure at least partially, wherein 0.2% of the pearlite structure
A pearlitic rail having excellent wear resistance and surface damage resistance, characterized in that the% proof stress is 600 to 1200 MPa. (3) C: contains more than 0.85% to 1.20% or less by weight, and further contains Si: 0.10 to 1.00% and Mn: 0.10 to 1. 50% At least a part is a steel rail exhibiting a pearlite structure, and the 0.2% proof stress of the pearlite structure is 600 to 1%.
A pearlitic rail excellent in wear resistance and surface damage resistance, characterized in that it has 200 MPa and a total elongation of 7 to 12%. (4) In weight%, C: more than 0.85% to 1.20% or less, Si: 0.10 to 1.00%, Mn: 0.10 to 0.10%
1.50%, Cr: 0.05 to 1.00%, Mo: 0.01 to 0.20%, Cu: 0.05 to 0.50%, Ni: 0.05 to 1.00%, V: 0.01 to 0.50%, Nb: 0.002 to 0.050%, B: 0.0001 to 0.0050%, Ti: 0.0050 to 0.0300% Mg: 0.0010 to 0.0100%, Ca: 0.0010 to 0.0150%, Co: 0.10 to 2.00%, the balance being iron and unavoidable impurities, A steel rail having at least a part having a pearlite structure, wherein the steel rail has a pearlite structure of 0.2%.
% Yield strength is 600 to 1200 MPa, and total elongation value is 7 to 12
%, A pearlitic rail having excellent wear resistance and surface damage resistance. (5) The wear resistance and surface resistance described in (1) to (4) above, wherein at least a range of a depth of 20 mm from the head corner portion and the top surface of the steel rail exhibits a pearlite structure. Pearlitic rail with excellent damageability.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail. In the present invention (1) to (7), the chemical components
The reason for limiting the range of the pearlite structure, the 0.2% proof stress, and the total elongation value to the above-described claims will be described in detail. (1) Chemical Composition of Rail Steel First, the reason for limiting the chemical composition of the rail in the present invention as described above will be described. C is an important element that promotes pearlite transformation and secures abrasion resistance. As a normal rail steel, the C content is 0.60 to 0.85.
However, if the C content is 0.85% or less, the density of the cementite phase in the pearlite structure for improving the wear resistance cannot be ensured, and furthermore, the starting point of the fatigue damage inside the rail head is reduced. Grain boundary ferrite is likely to be generated, and the rail life is shortened. On the other hand, when the C content exceeds 1.20%, the density of the cementite phase in the pearlite structure increases, the ductility of the pearlite structure decreases, and peeling damage called spalling tends to occur on the rolling surface, resulting in surface damage resistance. The property is deteriorated. Further, depending on the component system, a proeutectoid cementite structure is generated in the pearlite structure, and the toughness and ductility of the rail are greatly reduced.
Limited to 1.20%.

Usually, Si and Mn are further contained under the following conditions. Si is an element that increases the hardness (strength) of the rail head by solid solution hardening into the ferrite phase in the pearlite structure. However, if it is less than 0.10%, the effect cannot be expected sufficiently, and 1.00 is not obtained. %, A large number of surface flaws are generated during hot rolling, and weldability is reduced due to generation of oxides.
%.

Mn lowers the pearlite transformation temperature,
It is an element that contributes to high strength by improving hardenability and further suppresses the formation of a proeutectoid cementite structure. However, its effect is small when the content is less than 0.10%,
It is difficult to secure the required hardness of the rail head. If the content exceeds 1.50%, the hardenability is remarkably increased, a martensite structure is easily formed, segregation is promoted, and a pro-eutectoid cementite structure harmful to rail toughness is formed in the segregated portion. Mn amount is 0.10 to 1.5
Limited to 0%.

Further, one or more of the following elements may be added to the rail manufactured with the above-mentioned composition as required for the purpose of improving strength, ductility and toughness. Cr: 0.05 to 1.00%, Mo: 0.01 to 0.20%, Cu: 0.05 to 0.50% Ni: 0.05 to 1.00%, V: 0.01 to 0 .50%, Nb: 0.002 to 0.050%, B: 0.0001 to 0.0050%, Ti: 0.0050 to 0.0300%, Mg: 0.0010 to 0.0100%, Ca: 0.0010 to 0.0150%, Co: 0.10 to 2.00%

Next, the reasons for defining these chemical components as described above will be described. Cr is an element that raises the equilibrium transformation point of pearlite and consequently refines the pearlite structure to contribute to high strength, and at the same time, enhances the wear resistance by strengthening the cementite phase in the pearlite structure, If it is less than 0.05%, the effect is small, and if it is added excessively exceeding 1.00%, a large amount of martensite structure is generated and the toughness of the rail is reduced. Limited to 00%.

Mo is an element which raises the equilibrium transformation point of pearlite like Cr and consequently makes the pearlite structure finer, thereby contributing to higher strength and improving wear resistance, but less than 0.01%. The effect is small.
Excessive addition exceeding 20% promotes segregation,
Further, the pearlite transformation rate decreases, a martensite structure is generated in the segregated part, and the toughness of the rail decreases,
The amount of Mo was limited to 0.01 to 0.20%.

Cu is an element for improving the strength without impairing the toughness of the pearlite steel, and its effect is 0.05 to 0.1.
The largest amount is in the range of 50%, and if it exceeds 0.50%, red heat embrittlement is likely to occur.
Limited to 5 to 0.50%.

Ni is an element that improves the ductility and toughness of the pearlite steel and, at the same time, enhances the strength of the pearlite steel by solid solution strengthening. Even if excessive addition exceeding 0.000% is performed, no further effect can be expected. Therefore, N
The i amount was limited to 0.05 to 1.00%.

V is V generated during the cooling process during hot rolling.
Increases strength by precipitation hardening with carbides and V-nitrides, and further refines austenite grains by the action of suppressing the growth of crystal grains when heat treatment is performed at a high temperature, resulting in the strength, ductility and toughness of pearlite structure. Is an effective component for improving the V content, but if it is less than 0.01%, its effect cannot be expected sufficiently, and if it exceeds 0.50%, no further effect can be expected. 0.0
Limited to 1 to 0.50%.

Like V, Nb increases the strength by precipitation hardening with Nb carbide and Nb nitride, and further reduces the size of austenite grains by the action of suppressing the growth of crystal grains during heat treatment at a high temperature. The effect of suppressing austenite grain growth acts up to a temperature range higher than V (around 1200 ° C.), and improves the ductility and toughness of the pearlite structure. The effect cannot be expected if it is less than 0.002%, and no further effect can be expected even if an excessive addition exceeding 0.050% is performed. Therefore, the Nb amount is set to 0.0
It was limited to 02 to 0.050%.

B is iron boride (Fe ₂₃ (CB) ₆ )
Forming a pearlite transformation, thereby reducing the cooling rate dependency of the pearlite transformation temperature,
It is an element that gives a more uniform hardness distribution from the rail head surface to the inside, but its effect is completely absent at a content of less than 0.0001%. Since a carbon boride is generated and causes a decrease in ductility and toughness, the amount of B is set to 0.0001 to 0.0050.
%.

[0023] Ti is a method for converting excess nitrogen in steel into nitride (Ti
N), and at the same time, the precipitation of B nitride (BN) is suppressed, and as a result, iron boride (Fe ₂₃ (C ₂₃
B) An element that preferentially produces ₆ ) and promotes pearlite transformation, but if the content is less than 0.0050%,
Not enough to form nitrides and 0.0300
%, Coarse nitrides (TiN) and carbides (TiC) are generated, which lowers the ductility and toughness of the rails and, at the same time, tends to be a starting point for fatigue damage during use of the rails. 0050 to 0.0300%.

Mg combines with O or S or Al to form a fine oxide, and suppresses the growth of crystal grains and refines austenite grains during reheating during rail rolling. Is an element effective for improving the ductility and toughness of the pearlite structure. Further, MgO and MgS are replaced with MnS
Is dispersed finely, and a thin band of Mn is formed around MnS, thereby contributing to the generation of pearlite transformation. As a result, by reducing the size of the pearlite block, it is possible to improve the ductility and toughness of the pearlite structure. It is an effective element. However, if less than 0.0010%, the effect is weak,
When added in excess of 0.0100%, a coarse oxide of Mg is formed to deteriorate the ductility and toughness of the rail. Therefore, the amount of Mg is limited to 0.0010 to 0.0100%.

Ca has a strong bonding force with S and forms a sulfide as CaS. Further, CaS finely disperses MnS, forms a dilute band of Mn around MnS, and forms pearlite transformation. It contributes, and as a result, is an element effective for improving the ductility and toughness of the pearlite structure by reducing the pearlite block size. But,
If less than 0.0010%, the effect is weak, and 0.0150
%, A coarse oxide of Ca is formed to deteriorate the ductility and toughness of the rail.
It was limited to ~ 0.0150%.

Co is an element that increases the transformation energy of pearlite to improve the strength by making the pearlite structure finer. If less than 0.10%, the effect cannot be expected, and 2.00%. However, the effect reaches the saturation range even if an excessive amount of addition is performed, so the Co content is limited to 0.10 to 2.00%.

The rail steel having the above-mentioned composition is melted in a commonly used melting furnace such as a converter or an electric furnace, and the molten steel is subjected to an ingot-bulking method or a continuous casting method.
Further, it is manufactured as a rail through hot rolling. next,
By applying a heat treatment to at least the head of this hot-rolled rail that holds high-temperature heat or a rail that has been reheated to a high temperature for the purpose of heat treatment, a pearlite structure with high hardness can be stably applied to the rail head. Can be generated.

As described above, it is desirable that the metal structure of the rail is a pearlite structure. However, depending on the component system, the accelerated cooling rate, and the segregation state of the material, a small amount of a proeutectoid ferrite structure or a proeutectoid cementite may be included in the pearlite structure. Tissue may be generated. However, even if traces of these structures are formed in the pearlite structure, they do not significantly affect the abrasion resistance, surface damage resistance, strength, ductility, and toughness of the rail. The pearlite structure includes a slight mixture of a proeutectoid ferrite structure and a proeutectoid cementite structure.

In the present invention, it is desirable that at least a part of the rail has a pearlite structure, and that at least 80% of the rail has a pearlite structure. And even if pearlite and a structure other than pearlite are finely mixed, the vicinity of the head surface of the rail may be a substantially pearlite structure and the other portion may be a structure other than pearlite.

(2) Range of the pearlite structure The desired range of the pearlite structure is set to a depth of 20 mm starting from the head surface at the corner and the top of the head.
The reason for limiting to the range is described. If the thickness is less than 20 mm, the wear resistance and internal fatigue damage resistance area required for the rail head is small, and a sufficient life improvement effect cannot be obtained due to progress of wear and occurrence of internal fatigue damage. It is more desirable that the range in which the pearlite structure is present has a depth of 30 mm or more starting from the head surface at the corner and top of the head, thereby further increasing the life-improving effect.

Here, FIG. 1 shows the nomenclature of the rail according to the present invention, which is excellent in wear resistance and internal fatigue damage resistance, at the surface position of the cross section of the head and the region where wear resistance is required. In the rail head, 1 is a crown, 2 is a head corner, and one of the head corners 2 is a gauge corner (GC) that mainly contacts the wheel.

(3) 0.2% proof stress of pearlite structure
The reason why the range is limited to the range of ~ 1200 MPa will be described. When the 0.2% proof stress of the pearlite structure is less than 600 MPa, the GC of the rail head generated by contact with the wheel is increased.
The plastic deformation area just below the rolling surface at the part and the head side part increases, and on the rail laid in the curved section, repeated contact with the wheel causes surface damage such as squeak cracking and flaking in the plastic deformation area. To increase. further,
The wear resistance is reduced and the wear life of the rail is greatly reduced. Further, the 0.2% proof stress of the pearlite structure is 1200M.
When the pressure exceeds Pa, the contact area (plastic deformation area) with the wheel at the rail head is significantly reduced due to an increase in proof stress, and excessive contact pressure due to local contact with the wheel occurs, causing spalling and the like. Since peeling damage is likely to occur, the range of 0.2% proof stress is limited to the range of 600 to 1200 MPa.
The 0.2% proof stress of the pearlite structure can be controlled by the composition of the steel and the rail manufacturing conditions such as hot rolling and subsequent straightening.

(4) Total elongation value of pearlite structure A desirable total elongation value in the range exhibited by the pearlite structure is 7
The reason for limiting the range to 12% will be described. When the 0.2% proof stress is within the above-mentioned limited range, the total elongation value of the pearlite structure is 6
% Or less, the ductility of the pearlite structure is reduced, and peeling damage (surface damage), which is called spalling, is likely to occur on the rolling surface. Further, it becomes difficult to secure the ductility required for the rail, and unstable fracture is likely to occur from a rail welding joint portion, a base material, or the like due to an excessive impact force applied from a vehicle or the like. When the total elongation value of the pearlite structure exceeds 13%, due to the improvement in ductility, the critical plastic deformation amount immediately below the rolling surface at the GC part or the head side part of the rail head caused by contact with the wheel. And the plastic deformation region where the wear resistance is not improved is expanded. As a result, due to repeated contact with the wheel, surface damage such as creaking and flaking is likely to occur in the plastic deformation region. Therefore, the total elongation value is preferably in the range of 6 to 13%. Furthermore, when the total elongation value is in the range of 7 to 12% as in the present invention, slight surface damage that does not pose a practical problem hardly occurs, and further sufficient surface damage resistance can be obtained. The total elongation value of the pearlite structure can be controlled by the steel composition and rail manufacturing conditions such as hot rolling.

[0034]

Next, an embodiment of the present invention will be described. Table 1 shows the chemical composition, microstructure, 0.2% proof stress and total elongation of the rail steel of the present invention in a tensile test. Table 1 shows the amount of wear after 700,000 repetitions in the Nishihara type abrasion test under forced cooling conditions shown in FIG. 2, and disk test pieces obtained by reducing the rail and wheel shapes shown in FIG. The results of water-lubricated rolling fatigue damage test were also described.

[0035]

[Table 1]

Table 2 shows the chemical composition, microstructure, 0.2% proof stress and total elongation of the comparative rail steel in a tensile test.
Table 1 shows the amount of wear after 700,000 repetitions in the Nishihara type abrasion test under forced cooling conditions shown in FIG. 2, and disk test pieces obtained by reducing the rail and wheel shapes shown in FIG. The results of water-lubricated rolling fatigue damage test were also described.

[0037]

[Table 2]

FIG. 4 shows the relationship between the 0.2% proof stress and wear of the rail steel of the present invention and the comparative rail steel (symbols: M to O, eutectoid carbon-containing steel).

The configuration of the rail steel is as follows. -Rail steel of the present invention (12) Symbols A to L Within the above component ranges, at least a part of the steel rail exhibits a pearlite structure, and the 0.2% proof stress of the pearlite structure is in a range of 600 to 1200 MPa. A pearlitic rail with excellent wear resistance and surface damage resistance.
Alternatively, within the above component range, at least a part of the steel rail exhibits a pearlite structure, and the steel rail has a pearlite structure of 0.2%.
% Yield strength is 600 to 1200 MPa, and total elongation value is 7 to 12
% Perlite rail with excellent wear resistance and surface damage resistance.

Reference Rail Steel (6 pieces) Symbols M to R Symbols M to O: A comparative rail steel made of a eutectoid carbon-containing steel whose chemical composition is outside the above-mentioned claims. Reference symbol P: a comparative rail steel made of a hypereutectoid carbon-containing steel whose chemical composition is outside the above-mentioned claims. Symbols Q to R: Comparative rail steels made of hypereutectoid carbon-containing steels whose 0.2% proof stress is out of the above-mentioned claims.

The conditions for the tensile test were as follows. Tester: Universal small tensile tester Test piece shape: Similar to JIS No. 4 Parallel part length: 25 mm, Parallel part diameter: 6 mm, Distance between elongation measurement evaluation points: 21 mm Tensile speed: 10 mm / min Test temperature: Room temperature (20 ° C.)

The wear test conditions were as follows. Testing machine: Nishihara type abrasion tester Shape of test piece: Disc-shaped test piece (outer diameter: 30 mm, thickness: 8 mm) Test load: 686 N Sliding rate: 20% Counterpart material: pearlite steel (Hv390) Atmosphere: Cooling in air: Forced cooling by compressed air (flow rate: 100 Nl / min) Number of repetitions: 700,000 times The rolling fatigue damage test conditions were as follows. -Testing machine: Rolling fatigue damage testing machine-Specimen shape: disk-shaped specimen (outer diameter: 200mm, rail material cross section: 1/4 model of 60K rail)-Test load: Radial load: 1.5 tons Thrust load : 0.3 ton ・ Atmosphere: Drying + water lubrication (60cc / min) ・ Rotation speed: Drying (0-5000 times): 100rpm Drying + water lubrication (5000 times-): 300rpm ・ Repetition number: 0-5000 times In the dry state, then 3 million times by water lubrication or until damage occurs. If a small crack or peeling (1-2 mm) occurs on the rolling surface during the test, test up to 3 million times as long as the damage does not progress. Was continued.

As shown in FIG. 4, within the range of 0.2% proof stress of the present invention, the rail steel of the present invention is a comparative rail steel containing eutectoid carbon (symbols: M to O, eutectoid carbon-containing steel). By increasing the carbon content, the amount of wear is small at the same hardness, and the wear resistance is greatly improved.

As shown in Tables 1 and 2, within the range of 0.2% proof stress of the present invention, the rail steel of the present invention has a higher carbon content in the hypereutectoid steel than the comparative rail steel (P: P). Within the appropriate range, a pearlite structure having a high hardness can be stably obtained without generating a proeutectoid cementite structure harmful to the toughness and ductility of the rail. Also,
Compared with the comparative rail steel (code: Q to R), the rail steel of the present invention has a 0.2% proof stress within an appropriate range,
Flaking and spalling damage can be prevented, and surface damage resistance is greatly improved.

[0045]

As described above, according to the present invention, the component composition,
By setting the structure, the 0.2% proof stress, and the total elongation value within a certain range, a rail having excellent wear resistance and surface damage resistance can be provided to a heavy-load railway.

[Brief description of the drawings]

FIG. 1 is a drawing showing names of rail cross-sectional surface positions.

FIG. 2 is a schematic drawing of a Nishihara type abrasion tester.

FIG. 3 is a schematic drawing of a rolling fatigue damage tester.

FIG. 4 shows a rail steel according to the present invention and a comparative rail steel (symbols: M to M).
FIG. 2 shows the relationship between the 0.2% proof stress and the wear amount of O, eutectoid carbon-containing steel).

[Explanation of symbols]

 1: Top part 2: Head corner part 3: Rail test piece 4: Counterpart material 5: Rail disc test piece 6: Wheel test piece 7: Motor (rail side) 8: Motor (wheel side) 9: Water lubrication device

Claims (7)

[Claims] 1. A steel rail comprising, by weight, C: more than 0.85% to 1.20% or less, and at least a part of the steel rail having a pearlite structure, wherein the pearlite structure has a 0.2% proof stress. A pearlite-based rail excellent in wear resistance and surface damage resistance, which is 600 to 1200 MPa. 2. The composition contains, by weight%, C: more than 0.85% to 1.20% or less, Si: 0.10 to 1.00%, and Mn: 0.10 to 1.50%. A pearlitic rail having excellent wear resistance and surface damage resistance, wherein the steel rail has a pearlite structure, wherein the pearlite structure has a 0.2% proof stress of 600 to 1200 MPa. 3. The composition according to claim 1, further comprising: C: more than 0.85% to 1.20% or less, Si: 0.10 to 1.00%, and Mn: 0.10 to 1.50%. , Cr: 0.05 to 1.00%, Mo: 0.01 to 0.20%, Cu: 0.05 to 0.50%, Ni: 0.05 to 1.00%, V: 0.01 0.50%, Nb: 0.002 to 0.050%, B: 0.0001 to 0.0050%, Ti: 0.0050 to 0.0300%, Mg: 0.0010 to 0.0100%, Ca: 0.0010 to 0.0150%, Co: 0.10 to 2.00%, one or more of which contains iron and unavoidable impurities, at least a part of which has a pearlite structure. A steel rail comprising the pearlite structure of 0.2
A pearlitic rail having excellent wear resistance and surface damage resistance, characterized in that the% proof stress is 600 to 1200 MPa. 4. A steel rail containing, by weight, C: more than 0.85% to 1.20% or less, at least a part of which exhibits a pearlite structure, wherein the pearlite structure has a 0.2% proof stress. A pearlitic rail excellent in abrasion resistance and surface damage resistance, characterized by having a total elongation value of 600 to 1200 MPa and a total elongation of 7 to 12%. 5. The composition according to claim 1, wherein C: more than 0.85% to 1.20% or less, Si: 0.10 to 1.00%, and Mn: 0.10 to 1.50%. A steel rail having a pearlite structure in which the 0.2% proof stress of the pearlite structure is 600 to 1200 MPa and the total elongation value is 7 to 12%. Excellent perlite rail. 6. In% by weight, C: more than 0.85% to 1.20% or less, Si: 0.10 to 1.00%, Mn: 0.10 to 1.50%, , Cr: 0.05 to 1.00%, Mo: 0.01 to 0.20%, Cu: 0.05 to 0.50%, Ni: 0.05 to 1.00%, V: 0.01 0.50%, Nb: 0.002 to 0.050%, B: 0.0001 to 0.0050%, Ti: 0.0050 to 0.0300%, Mg: 0.0010 to 0.0100%, Ca: 0.0010 to 0.0150% Co: 0.10 to 2.00%, one or more of which contains iron and inevitable impurities, and at least a part of which has a pearlite structure. A rail comprising 0.2 of said perlite structure;
% Yield strength is 600 to 1200 MPa, and total elongation value is 7 to 12
%, A pearlitic rail having excellent wear resistance and surface damage resistance. 7. The steel according to claim 1, wherein at least a region having a depth of 20 mm from the head corner and the top surface of the steel rail has a pearlite structure. Pearlitic rail with excellent wear resistance and surface damage resistance.