JP2001098342A - High strength bainitic rail excellent in joinability of flash butt weld zone and producing method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a bainitic rail having the joinability in the flash butt welding equal to or above that of the conventional pearlitic rail and also having excellent wear resistance and damage resistance. SOLUTION: This rail composed of steel contains, by weight, 0.25 to 0.4% C, 0.1 to 1% Si, 0.6 to 3.5% Mn, <=0.035% P, <=0.035% S, 0.05 to 2% Cr and 0.05 to 0.15% Nb, and consists of a steel satisfying the following inequality (1). The rail head has a bainitic structure, and hardness is controlled to 400 to 500 HV in both positions of the rail top part and head corner parts: 2<=Mn%/Si%<=6 (1).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to abrasion resistance and flaking resistance required under the condition of contact between wheels and rails in a high axle heavy railway such as a mining railway, which is mainly used for traveling of a high-load freight car. The present invention relates to a high-strength bainite rail excellent in jointability of a flash butt welded part, in addition to damage resistance such as the above, and a method of manufacturing the same.

[0002]

2. Description of the Related Art Conventionally, from the viewpoint of emphasizing abrasion resistance, only high strength has been aimed at using pearlite steel.
However, with the recent increase in the speed of railway transportation and the increase in axle weight, the use conditions of rails have become increasingly severe.
In particular, in areas where mining railways mainly transport ore, rail damage such as abrasion and flaking of curved rails has become a problem. Current pearlitic steel heat treated rail has a strength of 1
The level is about 300 MPa, and this level is necessary from the viewpoint of wear resistance, but the damage resistance is not sufficient. Further, it is industrially difficult to simultaneously improve the wear resistance and the other damage resistance with pearlite steel.

[0003] On the other hand, bainite steel is superior to pearlite steel in damage resistance such as flaking resistance, but has a problem in that wear resistance is reduced.

[0004]

The wear characteristics are described in the bainite steel high-strength rail disclosed in JP-A-5-271871 and JP-A-8-92696. The aim is to increase the amount of wear by applying bainite steel to improve the damageability. This method has a sharp curve under high axle load conditions.
There is a disadvantage that the rail life is shortened by promoting the wear of the head.

As described above, bainite rails aim to improve the resistance to rolling contact fatigue mainly by increasing the amount of wear, and attempts have been made to balance the amount of wear with the strength. Is not done enough.

[0006] Conventionally, rails are connected by forming bolt holes in the abdomen near the ends with a basic length of 24 to 25 m and connecting the seam plate with bolts. In this case, the seam had a gap of several to several tens of mm to absorb the thermal expansion caused by the temperature difference between summer and winter. However, these gaps impact the rails, wheels of the wagons and bogies when passing wagons,
On the rails, damages such as breakage of joint bolt holes and deformation of the head may occur. In particular, in recent years, the possibility of damage has increased due to the increase in the weight of freight cars.Therefore, the frequency of welding rails for the purpose of reducing seams with gaps has become extremely high. Are required to be bonded.

[0007] When an alloy element is added to a bainite rail to increase the strength, there is a high possibility that a problem will occur in the joinability at the time of flash butt welding, but no study has been made from such a viewpoint.

An object of the present invention is to provide a bainite rail having excellent abrasion resistance and damage resistance with the same joining property at the time of flash butt welding as the conventional pearlite rail in view of such conventional problems. And a method for manufacturing the same.

[0009]

In order to solve the above problems and achieve the object, the present invention uses the following means. (1) The bainite rail of the present invention has a C.I.
0.25 to 0.4%, Si: 0.1 to 1%, Mn:
0.6-3.5%, P: 0.035% or less, S:
0.035% or less, Cr: 0.05 to 2%, and Nb:
A rail made of steel containing 0.05 to 0.15% and satisfying the following formula (1), wherein the rail head has a bainite structure, and the hardness is a rail top part and a head corner part. HV: 400 to 500 at any position of the high strength bainite rail with excellent jointability of the flash butt weld.

2 ≦ Mn% / Si% ≦ 6 (1) (2) The bainite rail of the present invention further includes, as a steel component, 1% or less of Ni: 1% or less and Mo: 2% or less by weight%. The high-strength bainite rail according to the above (1), which is excellent in joining property of the flash butt welded part, characterized by containing one or two kinds.

(3) The flash according to (1) or (2), wherein the bainite rail according to the present invention further contains V: 0.2% or less by weight as a steel component. High-strength bainite rail with excellent butt weldability.

(4) A step of hot rolling the steel having the composition described in any of the above (1) to (3) so that the finishing temperature of the steel is 800 to 1000 ° C. And cooling the hot-rolled steel sheet from a temperature above the bainite transformation start point to 200 ° C. or less at a cooling rate of air cooling or more and 5 ° C./sec or less. This is a method for manufacturing a high-strength bainite rail with excellent jointability at a butt weld.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS As a result of intensive studies to solve the above-mentioned problems, the present inventors have obtained the following findings.

(Jointability of Flash Butt Weld) S
i: Satisfies 0.1 to 1% and 2 ≦ Mn% / Si% ≦ 6.

The base material hardness is HV 500 or less.

Rail welding methods include flash butt welding, gas pressure welding, enclosed arc welding, and thermite welding. Of these, flash butt welding and gas pressure welding involve heating and joining the rail base material, and The joining property of the materials becomes a problem. The bondability at the time of flash butt welding is affected by the cleanliness of the base material, the formation of oxides at the bonding surface when heat is generated by flash current, the melting of oxides, and the removal of oxides during upset. FIGS. 1A and 1B show the influence of Si, Mn% / Si% on the bondability of a bainite steel having a hardness of HV 500 or less and having the components shown in Table 1 during flash butt welding.

[0017]

[Table 1]

The vertical axis in the figure indicates that a welded joint was prepared by flash butt welding using a 40φ round bar, and a tensile test was performed using a test piece sampled so that the joint surface of the joint was at the center of the parallel portion of the tensile test piece. The average value of the aperture value of the fractured portion when the test was performed is shown, and the larger the aperture value, the higher the bondability. As can be understood from FIGS. 1A and 1B, when the Si content is less than 0.1% or more than 1%, or when Mn% / Si% is less than 2 or more than 6, the aperture value is 5%. % Or less, and the bondability is significantly reduced.

Si is an element that is easily oxidized, and is also used as a deoxidizing material for steel. However, if it is less than 0.1%, sufficient deoxidation is not performed, so that the cleanliness of the steel is deteriorated and the bonding surface is oxidized. Things remain. When added in a large amount of 1% or more, a dense and stable oxide film is formed on the joint surface by heating with a flash current, and is not removed from the joint surface even in the final upset at the time of flash butt welding. Even when Si is 1% or less, the melting point of the composite oxide of Mn, Si, and Fe is Mn.
In a region where the ratio of% / Si% is less than 2 or more than 6, the temperature becomes high, and the viscosity of the composite oxide remaining on the joint surface becomes relatively high, so that it is difficult to remove it in the upset. Therefore, from the viewpoint of bonding properties, Si is 0.1 to 1%, and Mn% / S
i% needs to be 2 to 6.

FIG. 2 shows the result of examining the effect of the base metal hardness on the weldability during welding. Table 2 shows the chemical composition and base metal hardness of the test steel.

[0021]

[Table 2]

As can be understood from FIG. 2, Si, Mn% /
Even when each of Si% satisfies the claims of the present invention, the bondability decreases as the base material hardness increases.
When the value exceeds V500, the aperture value becomes 5% or less, which causes a practical problem. If any of Si, Mn% / Si% does not satisfy the claims of the present invention, HV400-
Even between 500 and 500, there is a problem in bondability. Therefore, in order to ensure sufficient bondability, Si is 0.1 to 1% and Mn% / S
It is necessary that i% is 2 to 6 and that the base material hardness is HV 500 or less.

Based on this finding, the present inventor has proposed that S
The i, Mn / Si amount, the rolling finish temperature in hot rolling and the cooling rate after rolling are controlled within a certain range to make the metal structure of the rail head bainite, and the top and corner of the rail head. By controlling the hardness within a certain range, a high-strength bainite rail excellent in the joining property of a flash butt weld and a method for producing the same have been found, and the present invention has been completed.

That is, the present invention limits the steel composition, hardness, microstructure (metal structure), and manufacturing conditions to the following ranges, thereby making the jointability at the time of flash butt welding equal to that of a conventional pearlite rail. Excellent wear resistance on the
A bainite rail having damage resistance and a method for manufacturing the same can be provided.

The reasons for adding the components, the reasons for limiting the components, the reasons for limiting the hardness, the reasons for limiting the metallographic structure, and the reasons for limiting the manufacturing conditions of the present invention are described below.

(1) Component composition range, hardness, and metal structure C: 0.25 to 0.4% C is an essential element for ensuring strength and wear resistance. It is difficult to secure the hardness of steel at low cost. On the other hand, if it exceeds 0.4%, brittle martensite is generated at the rail head. Therefore, 0.
Limited to 25-0.4%.

Si: 0.1-1% Si is not only effective as a deoxidizing agent, but also an element which increases the strength by forming a solid solution, but if it is less than 0.1%, the deoxidizing effect is not sufficient. The cleanliness in the steel is degraded, and oxides remain on the joint surface during flash butt welding, deteriorating the jointability. If the addition amount exceeds 1%, a large amount of solid-dissolved Si is formed as a dense oxide on the joining surface during flash butt welding, and the joining property is deteriorated by inhibiting the joining of the new surface. . Therefore, it was limited to 0.1 to 1%.

Mn: 0.6 to 3.5% Mn is an element that contributes to increasing the strength of the rail by lowering the bainite transformation temperature and increasing the hardenability. However, if it is less than 0.6%, the effect is small, and if it exceeds 3.5%, a martensitic structure is liable to occur due to micro-segregation of the steel, and the material deteriorates in the weld heat affected zone, which is not preferable.
Therefore, it was limited to 0.6 to 3.5%.

P: 0.035% or less Since P deteriorates toughness, it is limited to 0.035% or less.

S: not more than 0.035% S is present in steel mainly in the form of inclusions,
%, The amount of the inclusions increases remarkably and causes deterioration of the material due to embrittlement. Therefore, the content is limited to 0.035% or less.

Cr: 0.05 to 2% Cr is an element that promotes bainite transformation, and is a very important element for increasing the strength by converting the microstructure to a bainite structure as in the steel of the present invention. . If it is less than 0.05%, the microstructure does not become a uniform bainite structure. On the other hand, when it exceeds 2%, martensite is easily generated. Therefore, it was limited to 0.05 to 2%.

Nb: 0.05 to 0.15% Nb not only promotes bainite transformation but also precipitates as carbonitride after rolling, so that the hardness is increased by precipitation strengthening up to the inside of the head to improve the resistance. Improves abrasion. However, this effect is not effective when Nb is added in less than 0.05%, and the effect is saturated even when Nb is added in excess of 0.15%. Therefore, it was limited to 0.05 to 0.15%. 2 ≦ Mn% / Si% ≦ 6 One of the features of flash butt welding is scattering of an oxide film on a joint surface by a flash current and removal of the oxide film by melting due to heat generation. Therefore, it is desirable that the oxide formed on the bonding surface has a composition that is easily melted. FIG.
As can be understood from (b), when Mn% / Si% is less than 2 or more than 6, the aperture value becomes 5% or less, and the bondability is significantly reduced. This is because the Fe-M
This is because if the n-Si-based composite oxide is between 2 and 6 in Mn% / Si%, it has a low melting point and is easily removed. Therefore, from the viewpoint of the joining property of the flash butt weld, Mn%
The ratio of / Si% was limited to 2-6.

Further, in the present invention, in addition to the above components, Ni, Mo, and V may be added in the following ranges as needed.

Ni: 1% or less, Mo: 2% or less Both Ni and Mo are effective elements for promoting bainite transformation and increasing the strength. Will saturate. Therefore, it is effective to add one or two kinds within the above-mentioned claims.

V: 0.2% or less V, like Nb, combines with C in the steel and precipitates after rolling. Therefore, the hardness is increased by precipitation strengthening to the inside of the head to improve the wear resistance. It is effective to extend the life of the rail. However, even if it exceeds 0.2%, the effect is saturated. Therefore, it is effective to add V within the above-mentioned claims.

Hardness (abrasion resistance, damage resistance): HV400 at any position at the top of the rail and at the corner of the head
~ 500.

Although it is most desirable to evaluate the amount of abrasion by the amount of abrasion in actual laying, it is also effective to use a Nishihara-type abrasion tester to evaluate the abrasion by a comparative test simulating actual contact conditions. By using this test method, it is possible to evaluate the wear resistance (the relationship between the hardness and the wear loss ratio) in a short period of time. Similarly, a comparative test can be performed on the damage resistance.

FIG. 3 (a) shows the results of an investigation on the effect of hardness on the wear loss ratio. The test steel is a steel whose composition is shown in Table 3 and is heated to 1250 ° C and after rolling at 920 ° C,
A 12 mm thick steel sheet air-cooled at 0.5 ° C./sec was used. A Nishihara type abrasion test piece having an outer diameter of 30 mm and a width of 8 mm was sampled from these steel sheets, and the contact load was 250 kg and the slip rate was −
A wear test was performed under the conditions of 10% and no lubricant, and the loss on wear after 100,000 rotations was measured. In the evaluation, the wear loss of the pearlite rail was measured, and the wear loss ratio of the test steel to the pearlite rail was determined.

[0039]

[Table 3]

The hardness of the heat-treated pearlite rail is HV3
It is about 80. As can be understood from FIG. 3A, the wear loss ratio decreases as the hardness increases, and the bainite steel has a larger wear loss ratio than the pearlite steel at the same hardness. However, the hardness of bainite steel is HV4
If it is 00 or more, wear resistance equivalent to that of the heat-treated pearlite rail can be obtained.

Attempts have been made to control the contact state with the wheels by intentionally changing the hardness of the crown and the corners of the head, but on actual routes, the contact between the wheels and the rails is limited. It is practically difficult to extend the rail life by controlling the contact state by changing the hardness of the head. Therefore, the hardness distribution was uniform at both the top and the corner of the head.

FIG. 3B shows the influence of the structure and hardness on the flaking occurrence life as an evaluation of damage resistance. The test steel used was the same as that shown in FIG. The damage was evaluated by using a Nishihara type abrasion test piece with a radius of curvature of 15 mm on the contact surface under oil lubrication, contact load of 100 kg, slip rate of -20%, and measuring the time when the damage occurred. did. As shown in this figure, bainite steel has a longer flaking generation life than pearlite steel at the same hardness. By setting the HV to 400 or more for bainite steel, a life twice as long as that of currently used pearlite steel can be obtained.

From the viewpoint of wear resistance and damage resistance, bainite steel requires HV 400 or more, and from the viewpoint of bondability, HV 500 or less is required. is there.

Metallographic structure: Bainite bainite structure has high fatigue strength, is effective in damage resistance, and has high strength when compared with the pearlite structure of the conventional rail at the same tensile strength level. The microstructure (metal structure) is a bainite structure because the wear amount can be made equal to the pearlite structure.

By adjusting the component composition range, hardness and metal structure as described above, it is possible to obtain a high-strength bainite rail excellent in the joining property of the flash butt welded portion. A rail having such characteristics can be manufactured by the following manufacturing method.

(2) Rail Manufacturing Process (Manufacturing method) Steel adjusted to the above component composition range is melted in a converter and converted into a slab by continuous casting, and then the rolling finish temperature is adjusted to 800 to 1000 ° C. And from the temperature above the bainite transformation start point to 200 ° C. or less, at a cooling rate of air cooling or more and 5 ° C./sec or less.

A. Rolling finishing temperature: 800 to 1000 ° C If the rolling finishing temperature is lower than 800 ° C, the hot deformation resistance during rolling increases, and the dimensional accuracy of the rail cannot be satisfied. On the other hand, if the rolling finish temperature exceeds 1000 ° C., austenite grains become coarse and the toughness deteriorates. Therefore, the rolling finishing temperature is 800 to 1000 ° C.

B. Cooling rate: not less than air cooling and not more than 5 ° C./sec As for the cooling rate, a bainite structure can be obtained in the range of cooling rate not less than air cooling and not more than 5 ° C./sec, and desired strength and toughness can be secured. However, when the temperature exceeds 5 ° C./sec, martensite is formed, and the toughness is significantly reduced. Therefore, the cooling rate is not less than air cooling and not more than 5 ° C./sec.

The effects of the present invention will be proved by the following examples.

In the text, figures and tables, HV represents Vickers hardness, and RA represents the aperture value in a tensile test of the joint surface after flash butt welding as an evaluation of jointability.

[0051]

EXAMPLES (Example 1) Test steels having the components shown in Table 4 (Nos. 4-2 to 4: Examples of the present invention;
6: Comparative Example) was heated to 1250 ° C., and after rolling at 920 ° C., a 12 mm-thick steel sheet accelerated and cooled at 2 ° C./sec was used to measure hardness, abrasion test, flaking test, and joinability. An evaluation test was performed. For wear test, outer diameter 30m
m, a test piece having a width of 8 mm was sampled from a rolled steel plate, and a tire test piece having the same dimensions was sampled from a railway wheel material. The test was performed under the condition without a lubricant, and the abrasion loss after 100,000 rotations was measured. In addition, H performed as a comparison
The wear loss ratio is determined by taking the ratio with the wear loss of the rail steel having the pearlite structure of V380. In the flaking test, the outer diameter was 30 mm, the width was 8 mm, and the radius of contact was 15 m.
Using a test piece having a curvature of m, a wear test was performed at a slip rate of −10% and a contact load of 100 kg under oil lubrication conditions.
The time when the contact surface was damaged was measured, and the damage resistance was evaluated. Table 5 shows the hardness, the wear loss ratio, the life of occurrence of flaking, and the bondability.

Comparative Example No. 1 having a lower C content than the present invention. 4-
With respect to 1, the hardness is HV371, which is less than the lower limit of the present invention, and the wear loss ratio is as high as 1.81, which is not suitable for practical use.
Comparative Example No. having a higher C content than the present invention. 4-5, 6
As for, the microstructure shows a pearlite structure,
Excellent wear properties but poor damage resistance.

On the other hand, in the case of the present invention sample No. 4-2, 3, and 4 show excellent values in all of hardness, wear reduction ratio, and flaking occurrence life. Regarding the bondability, Mn% / Si% is 2 to 6 in all cases, and HV is 500 or less, indicating a sufficient value.

[0054]

[Table 4]

[0055]

[Table 5]

(Example 2) Test steels having components shown in Table 6 (Nos. 6-1 to 6, 9, 10, and 13: Examples of the present invention, N
o. 6-1, 7, 8, 11, 12, and 14: Comparative Example), a hardness measurement, a wear test, a flaking test, and a bondability evaluation test were performed in the same manner as in Example 1. Hardness, wear loss ratio,
Table 7 shows the life of occurrence of flaking and bondability.

All the test steels have a bainite structure. In Comparative Example No. 1 in which the contents of Mn, Cr, and Nb were lower than the claims. Nos. 6-1, 8 and 11 show high values of bondability but low hardness, and a wear loss ratio of 3.15,
It shows high values of 3.45 and 3.22.

On the other hand, the content of Mn, Cr and Nb satisfying the claims of the present invention No. 1 of the present invention. 6-2, 3,
Nos. 4, 5, 6, 9, 10, and 13 show excellent values in all of hardness, wear reduction ratio, flaking generation life, and bonding property.

However, in Comparative Example No. in which the contents of Cr and Nb were higher than in the present invention. 6-12, 14: Cr, Nb
The effect of improving abrasion resistance and flaking resistance is saturated, and no improvement in characteristics is observed. In Comparative Example No. In the case of 6-7, since Mn% / Si% exceeds 6, the bondability is reduced.

[0060]

[Table 6]

[0061]

[Table 7]

(Example 3) Test steels having the components shown in Table 8 (Nos. 8-1 to 4, 7, 8, 10: Examples of the present invention, N
o. 8-5, 6, 9, 11: Comparative Example)
A hardness measurement, an abrasion test, a flaking test, and a bondability evaluation test were performed in the same manner as described above. Table 9 shows the hardness, wear reduction ratio, flaking occurrence life, and bonding property.

All the test steels have a bainite structure. Invention Example No. 8-1 does not contain Ni, Mo, and V, but is a component within the scope of the present invention, and each of the hardness, the wear loss ratio, the life of flaking, and the bondability are within the scope of the claims. . Inventive Example No. 1 in which the amount of one or two of Ni and Mo satisfies the claims. 8-2,
Samples Nos. 3, 4, and 7 show values of hardness, abrasion loss ratio, life of flaking and joining property within the range of claims. It shows a value superior to 8-1.
In Comparative Example No. where the amounts of Ni and Mo added exceeded the scope of the present invention.
Nos. 8-5, 6, and 9 have hardness, abrasion loss ratio, flaking generation life, and bondability. 8-4, 7 and the effect of the addition of Ni and Mo is saturated. Inventive Example No. V in which the addition amount of V satisfies the claims. 8-8,10
Indicates hardness, abrasion loss ratio, flaking occurrence life, and bondability, all within the range of claims.
o. 8-1 and 7 are superior to those of Comparative Examples Nos. 8 and 7, but the amount of V exceeds the scope of the present invention. 8-11 is hardness,
The abrasion loss ratio, the life of the flaking occurrence, and the bondability were the same as those of Example No. 8-10, and the effect of V addition is saturated.

[0064]

[Table 8]

[0065]

[Table 9]

(Example 4) Test steels having the components shown in Table 10 (Nos. 10-2, 3, 5, 6: Examples of the present invention;
10-1, 4, 7, 8: Comparative Example), a hardness measurement, an abrasion test, and a bondability evaluation test were performed in the same manner as in Example 1. Table 11 shows the hardness, the wear loss ratio, and the bondability. All test steels have a HV of 400 to 500 in bainite structure.
Si content satisfies the claims of the present invention, and Mn%
/ No. Of the present invention No./Si% in the range of 2 to 6. 10-
2, 3, 5, and 6 show excellent values in all of the hardness, the wear loss ratio, and the bondability.

However, in Comparative Example No. 1 in which the amount of Si exceeded 1%.
Comparative Example No. 10-1, where Mn% / Si% is less than 2 or more than 6. 10-4, 7, and 8 have inferior bondability.

[0068]

[Table 10]

[0069]

[Table 11]

(Example 5) Table 12 shows Example Nos. Of the present invention satisfying the component conditions of the present invention. 12-1 and 12 show steel. Table 13
The rolling finish temperature of these two steel types was 760 to 103
Rolled to a rail shape while changing the temperature to 0 ° C., and then changing the cooling rate from air cooling to 6.5 ° C./sec to show the hardness, wear reduction ratio, flaking occurrence life, and bondability of the manufactured rail (No. .2, 6, 8 to 10, 12: Examples of the present invention, N
o. 1, 7, 11, 13: Comparative Example). The abrasion loss ratio and the flaking generation life were evaluated by the same test method as in Example 1 by taking the sample shown in Example 1 from the head of the rolled material.

In Condition 1 (Comparative Example No. 1), the cooling rate satisfies the condition, but the rolling finish temperature is not satisfied, so that the bondability is good but the wear characteristics are inferior.

Conditions 2, 3, 4, 5, 6, 8, 9, 10,
12 (Examples Nos. 2 to 6, 8 to 10, and 12 of the present invention) satisfy the rolling finishing temperature and the cooling rate, and therefore have good hardness, abrasion resistance, and flaking resistance, and Is also excellent.

The conditions 7 and 11 (Comparative Examples Nos. 7 and 11) satisfy the conditions of the rolling finish temperature, but the cooling rate is too fast, so that the HV becomes a value of 500 or more.
Although the flaking resistance is good, the bondability deteriorates.
In condition 13 (Comparative Example No. 13), the finish temperature of rolling was high and the structure was coarse, so that the hardenability was high and the HV was 500.
And the bondability is poor.

[0074]

[Table 12]

[0075]

[Table 13]

[0076]

As described above, according to the present invention,
By specifying the steel composition, hardness, metal structure, and manufacturing conditions, it is possible to manufacture a high-strength bainite rail excellent in the joining property of a flash butt weld.

[Brief description of the drawings]

FIG. 1A is a diagram showing the effect of Si on the joining property during flash butt welding, and FIG. 1B is a diagram showing the effect of Mn% / Si% on the joining property during flash butt welding.

FIG. 2 is a diagram showing the effect of hardness on the joining properties during welding.

3A is a diagram showing the effect of hardness on the wear loss ratio, and FIG. 3B is a diagram showing the effect of the structure and hardness on the flaking generation life.

Claims (4)

[Claims] 1. The method of claim 1 wherein the C.I. 0.25 to 0.4%,
Si: 0.1-1%, Mn: 0.6-3.5%,
P: 0.035% or less, S: 0.035% or less, C
A rail containing r: 0.05 to 2% and Nb: 0.05 to 0.15% and satisfying the following formula (1), wherein the rail head has a bainite structure. The hardness is H at any position of the top of the rail and the corner of the head.
V: A high-strength bainite rail excellent in bondability of a flash butt weld, characterized by being 400 to 500. 2 ≦ Mn% / Si% ≦ 6 (1) 2. The steel composition further comprises Ni:
2. The high-strength bainite rail according to claim 1, comprising one or two of 1% or less and Mo: 2% or less. 3. 3. The steel composition further comprises, in weight%, V:
The high-strength bainite rail according to claim 1 or 2, characterized in that it contains 0.2% or less. 4. A step of hot rolling a steel having the composition according to any one of claims 1 to 3 so that a rolling finish temperature is 800 to 1000 ° C .; A step of cooling at a cooling rate of not less than 5 ° C./sec to air cooling from a temperature not lower than the starting point of init transformation to not more than 200 ° C., characterized by comprising: Manufacturing method of bainite rail.