JP4220830B2 - Perlite rail excellent in toughness and ductility and manufacturing method thereof - Google Patents

Description

【００５５】
【表２】

【００５６】
【発明の効果】
以上説明したように、本発明により微細なパーライト組織が得られ、靭性および延性に優れたパーライト系レールまたはその製造方法を提供できる。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a high-strength rail in which the pearlite structure of rail steel is refined to improve toughness and ductility, and a method for manufacturing the same.
[0002]
[Prior art]
In rail transport, heavy loads for improving transport efficiency and high speed for speeding up transport are being promoted, and demands on the characteristics of rails are becoming strict. Heavy loading promotes wear of the rail head in a sharp curve section and increases fatigue damage from the stress concentration portion inside the rail GC (gauge corner), and therefore the rail life is shortened. In order to improve the shortening of the rail life in heavy-duty railways, technological development of high-strength rail steel having excellent wear resistance and internal fatigue damage resistance has been actively conducted. As a result, this high-strength rail is becoming widespread in curved sections.
[0003]
On the other hand, in cold districts, rail replacement due to occurrence of rail cracks is concentrated in the winter, and improving the toughness of the rail material is a necessary issue for extending the rail life. It is also important to improve the toughness and ductility of the rail material in order to improve the internal fatigue damage resistance of the head. In the pearlite structure, the toughness and ductility can be improved by making the structure fine.
[0004]
So far, refinement of the structure, toughness and ductility have been improved by the following methods.
(1) A method of accelerating cooling after reheating the rail once cooled to room temperature after hot rolling at a low temperature.
(2) A method in which the rail head is accelerated and cooled after the austenite grains are refined by controlled rolling.
(3) A method of obtaining a fine pearlite structure by promoting transformation from within the austenite crystal grain in addition to the austenite crystal grain boundary during pearlite transformation.
(4) A method of miniaturization by controlling the moving speed of the transformation interface during pearlite transformation and transforming a large number of transformation nuclei.
[0005]
[Problems to be solved by the invention]
In the above method (1), for example, as described in Patent Document 1, after pearlite transformation, the austenite grains are refined by reheating to a low temperature of 850 ° C. or lower, which is lower than the normal heating temperature. It is intended to improve the toughness and ductility by refining the structure of the steel. However, if heating is performed at a low temperature and the inside of the rail head is deepened, it is necessary to reduce the amount of input heat and heat for a long time. This heat treatment has a difficulty in hindering productivity and increasing manufacturing costs.
[0006]
The method (2) is intended to improve toughness and ductility by reducing the austenite grains by controlled rolling, as described in Patent Document 2 and Patent Document 3, for example. However, there is a problem also from the viewpoint of the ability of the rolling mill that requires a large rolling force, or the shape controllability that the cross-sectional shape of the rail and the dimensional accuracy in the longitudinal direction cannot be easily obtained.
[0007]
Furthermore, the method of (3) promotes nucleation of pearlite transformation using V carbonitride and Ti carbonitride deposited on MnS as transformation nuclei as described in Patent Document 4, for example. This is a method for refining the tissue. By this method, certain toughness and ductility improvements were obtained. However, when these carbonitrides are used, the transformation is completed at a high temperature as a result of active generation of transformation nuclei.
[0008]
In addition, the method (4) described above uses Mo for the purpose of suppressing the pearlite transformation speed and miniaturizing the pearlite block size, as presented in, for example, Patent Document 5 and Patent Document 6. However, Mo is an element that greatly increases the hardenability, and depending on the component system, there is a problem that a harmful different structure is generated.
[0009]
[Patent Document 1]
Japanese Patent Laid-Open No. 55-125321 [Patent Document 2]
JP 52-138427 A [Patent Document 3]
Japanese Patent Laid-Open No. 52-138428 [Patent Document 4]
JP-A-6-279928 [Patent Document 5]
Japanese Patent Laid-Open No. 2002-212777 [Patent Document 6]
Japanese Patent Application No. 2001-303013 Specification
[Means for Solving the Problems]
The pearlite structure has a structure called pearlite block, pearlite colony, or pearlite lamellar. A pearlite block is a region where the crystal orientation of ferrite is aligned, and can be said to be a crystal grain unit in a pearlite structure. When the high-temperature austenite structure is cooled and transformed into a pearlite structure, the pearlite phase growing in a polyhedral shape eventually becomes a pearlite block after the transformation is completed.
[0011]
At the transformation interface, the cementite phase and the ferrite phase grow parallel to each other and perpendicular to the interface while maintaining a constant layer spacing. The layered structure of cementite phase and ferrite phase is called pearlite lamellar structure. In the pearlite growth process, a region in which the orientation direction of ferrite and cementite, that is, the direction of the lamellar structure is different, is called a pearlite colony. The perlite block is composed of several perlite colonies.
[0012]
The impact value and ductility value increase as the pearlite block, which can be said to be a crystal grain unit of the pearlite structure, becomes finer. When pearlite steel eventually breaks, the crack progresses by bending in units of pearlite blocks with uniform crystal orientation. It is considered that the finer the pearlite block, the greater the energy for creating the new interface, which improves the impact value. In addition, the progress of cracking until it finally reaches rupture is delayed as the structure becomes finer, and the ductility is improved by increasing the amount of deformation.
[0013]
In the present invention, in order to obtain good ductility and toughness required in cold districts, the generation rate of transformation nuclei is increased by N during pearlite transformation, and the growth rate of pearlite growing from individual transformation nuclei is suppressed by Mo. Therefore, the transformation from a large number of transformation nuclei is made effective to achieve miniaturization.
[0014]
The gist of the present invention is as follows.
(1) In mass%,
C: 0.55-1.2%, Si: 0.1-1.2%,
Mn: 0.4 to 1.4%, N: 0.006 to 0.03%,
Mo: 0.006 to 0.070%
The K value represented by the following formula (1) is 0.2 or more and less than 0.35, the balance is Fe and unavoidable impurities, and the hardness within 10 mm below the surface of the head section is Hv350 or more, A rail excellent in toughness and ductility, characterized in that at least the rail head has a pearlite structure.
K = Si / 24 + Mn / 6 + Cr / 5 + Mo / 2 + Ni / 44 + V / 14 (1)
(2) In mass%,
C: 0.55-1.2%, Si: 0.1-1.2%,
Mn: 0.4 to 1.2%, N: 0.006 to 0.03%,
Mo: 0.006 to 0.070%
The K value shown by the following formula (1) is 0.2 or more and less than 0.35, and the L value shown by the following formula (2) is 1.2 or less, and the balance Fe and unavoidable impurities A rail excellent in toughness and ductility, characterized in that the hardness within 10 mm below the surface of the head section is Hv350 or more and at least the rail head has a pearlite structure.
K = Si / 24 + Mn / 6 + Cr / 5 + Mo / 2 + Ni / 44 + V / 14 (1)
L = Mn + Cr (2)
[0015]
(3) Further, S: 0.002 to 0.05% is contained in mass%.
(4) Further in mass%,
V: 0.005-0.070%, Nb: 0.004-0.05%,
Ti: 0.001 to 0.015%, Al: 0.002 to 0.050%,
Mg: 0.0020 to 0.0100%, Ca: 0.015 to 0.050%
1 type or 2 types or more are contained.
(5) Further in mass%,
Ni: 0.01 to 1.5%, Cu: 0.01 to 1.5%
1 type or 2 types of.
(6) Further, Cr: 0.1 to 1.0% is contained in mass%.
(7) Further, by mass%, B: 0.0001 to 0.005% is contained.
[0016]
(8) After forming the steel slab comprising the component according to any one of the above (1) to (7) on the rail by hot rolling, the steel is made into an austenite region temperature as it is hot rolled or by heating after hot rolling, A method for producing a pearlite rail excellent in toughness and ductility, wherein at least the surface layer of the head of the rail is accelerated and cooled between 700 and 550 ° C. at 1 to 10 ° C./sec.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
The components of rail steel are adjusted in converters, electric furnaces, and the like. If necessary, it is solidified through secondary refining such as degassing. Then, it passes through a plurality of rolling mills from a reheated high temperature range of 1000 to 1350 ° C., is gradually formed into a rail shape, and finally is finished into a rail shape at 800 to 1100 ° C. The metal structure in the high temperature rolling is an austenite structure.
[0018]
Thereafter, when the temperature reaches the pearlite transformation temperature, the pearlite transformation starts. In the phase transformation in polycrystalline materials such as steel, transformation nuclei are formed at the grain boundaries of the old structure, and transformation starts. A pearlite region that is growing from one transformation nucleus in austenite is called a pearlite nodule.
Transformation nucleation and nodule growth proceed simultaneously. When a nodule grows to some extent, it collides with an adjacent nodule and stops growing in that direction. Finally, the old austenite region is completely covered with pearlite, and the transformation is completed. From such a transformation mechanism, it is understood that the fineness of crystal grains is determined by the ratio of the frequency (rate) of transformation nucleation and the growth rate of nodules.
[0019]
Conventionally, studies have been conducted to reduce the ratio between the frequency (rate) of transformation nucleation and the growth rate of nodules. It is known that precipitates having a high degree of matching between the ferrite phase in pearlite and the crystal lattice, such as V carbonitride and Ti nitride, promote the nucleation rate.
[0020]
In order to utilize these techniques to a higher degree, the present inventors have investigated the transformation behavior in detail, and when the amount of N contained in the steel is large, even if V and Ti are not contained, austenite grains We discovered that the generation of pearlite transformation nuclei from the world became popular. The reason for the promotion of transformation from the austenite grain boundary by N is not clear at present, but is thought to be due to the change in the segregation state of C at the austenite grain boundary or the formation of nitride by a very small amount of nitride-forming elements. ing.
Conventionally, it is known that Mo suppresses pearlite transformation and refines the pearlite block size. However, it was not clear whether Mo was slowing the nucleation rate or the nodule growth rate.
[0021]
By examining the transformation behavior in detail, the present inventors have found that Mo significantly delays the growth rate of pearlite nodules. That is, the Mo-containing steel suppresses the growth of each nodule during the pearlite transformation, and as a result, it takes a long time to hit the adjacent nodule. In the meantime, it is understood that new pearlite transformation nuclei are generated from untransformed austenite, and the opportunity to grow as new nodules increases and the crystal grains become finer.
[0022]
On the other hand, Mo suppresses the progress of the pearlite transformation, and depending on the amount of other alloy elements, the pearlite transformation may be stopped without completing the pearlite transformation, and a bainite structure or a martensite structure may be generated. When a bainite structure is generated, the hardness is rather lowered, and the wear resistance is deteriorated. When a martensite structure is formed, it becomes a notch, and brittle fracture tends to occur, which is not preferable.
Therefore, in order to use Mo, it is necessary to set the entire alloy composition within an appropriate range and prevent the generation of harmful foreign structures.
[0023]
Generally, carbon equivalent is often used as an index representing hardenability. However, before and after the amount of eutectoid carbon used for the rail, carbon tends to lower the hardenability. In this range, it was considered appropriate to exclude C from the index indicating the hardenability.
Based on the experimental results, the present inventors considered that the K value represented by the following formula (1) is appropriate as an index indicating the hardenability in pearlite.
K = Si / 24 + Mn / 6 + Cr / 5 + Mo / 2 + Ni / 40 + V / 14 (1)
[0024]
As a result of investigating various Mo-containing steels, if the K value is less than 0.2, the hardenability is insufficient, and a high-strength and fine-grained pearlite structure cannot be obtained. On the other hand, if the K value is 0.35 or more, the hardenability becomes excessive, and unless the cooling rate is lowered to the cooling rate or less, the pearlite transformation is incomplete, resulting in bainite and martensite structures.
[0025]
By the way, steel containing alloy elements causes microsegregation between columnar crystals or dendritic crystals during solidification. Among the microsegregated elements, light elements such as C, N, and P are made uniform by diffusion during the cooling process after casting and reheating for hot rolling. However, heavy metal elements such as Mn are not easily uniformized in these processes. For this reason, the hardenability of the steel material is microscopically uneven due to microsegregation.
[0026]
Mo also causes microsegregation remarkably, and its hardenability is higher than that of other elements, so that Mo-containing steel tends to generate micro martensite in the segregation part.
In order to prevent this, it is necessary to reduce other elements that microsegregate simultaneously with Mo. According to the experiments by the present inventors, it is desirable to suppress the L value of the formula (2) indicating the total content of Mn and Cr often used in rail steel to 1.2% or less by mass%. .
[0027]
On the other hand, high strength of 1000 MPa or more is required in addition to high toughness in the curved portion of the high speed track and heavy load track. In this case, it is desirable that after rolling or once cooled to room temperature, it is reheated to the austenite region temperature and accelerated cooling between 700 and 550 ° C. which is the pearlite transformation temperature region.
When accelerated cooling is performed, the degree of supercooling from the equilibrium transformation temperature increases, and pearlite transformation occurs at lower temperatures. When the degree of supercooling increases, the lamella spacing of pearlite decreases and the strength increases, and the generation rate of transformation nuclei increases, so that the effect of making the pearlite block size fine can be used together.
[0028]
The accelerated cooling further increases the number of transformation nuclei and further refines the pearlite structure. As a result, it is possible to achieve a further increase in the rail steel and toughness. However, if the cooling rate during accelerated cooling is less than 1 ° C./sec, the required strength cannot be obtained, and if it exceeds 10 ° C./sec, bainite and martensite are generated, which is not preferable. In addition, when a cooling method using water spray or liquid immersion is employed during accelerated cooling, film boiling occurs in the steel material surface layer, and uneven cooling is likely to occur. Therefore, the cooling medium is preferably air or air-water mist.
[0029]
When a rail is used, it is often welded to reduce maintenance work of the rail end joint and to improve riding comfort. A heat-affected zone in which mechanical properties and metal structure are altered is generated in the weld due to heat. In the rail steel strengthened by the accelerated cooling, the heat-affected zone is softened because of slow cooling after welding. As a result, the wear of the welded portion may become uneven during use of the rail. In order to reduce this, it is effective to increase the amount of alloy so that it is difficult to soften even by slow cooling. Based on the slow cooling rate after flash butt welding, which is frequently used in developed countries, it is desirable to set the K value shown in the above equation (1) to 0.25 or more.
[0030]
Moreover, it can be said that the generation of the above-described microscopic martensite is caused by the fact that the hardenability is high due to the microsegregation and the temperature of this part is not sufficient in the pearlite transformation temperature range. Although the pearlite transformation temperature region varies depending on the alloy composition, it is 500 to 700 ° C. in the case of rail steel including the amount of C before and after eutectoid. Below this temperature range, the pearlite transformation stops. In order to complete the pearlite transformation of the micro-segregation part, as described above, the alloy amount of the segregation part is decreased, and the temperature at which the accelerated cooling is finished is set to 550 ° C. or more at the rail head surface temperature. It is desirable to complete the pearlite transformation upon subsequent cooling.
[0031]
As described above, by promoting the nucleation at the austenite grain boundary by N and suppressing the growth rate of nodules by Mo, the pearlite block size after transformation becomes fine, and a rail steel having excellent toughness and ductility can be obtained.
Such a fine pearlite structure needs to be formed at least on the head portion of the rail to which an impact load from the wheel is easily applied.
[0032]
The present invention will be described in detail below.
First, the reason for limiting the components of the rail steel will be described. The content of the component is mass%.
C: C is an essential element for increasing the strength and generating a pearlite structure in rail steel. If it is less than 0.55%, the required high-strength pearlite structure is difficult to obtain, and if it exceeds 1.20%, harmful pro-eutectoid cementite that embrittles the austenite grain boundaries is generated. Limited to 20%.
[0033]
Si: Si not only contributes to high strength by solid solution strengthening to the ferrite phase in the pearlite structure, but also has a slight toughness and ductility improving effect. If it is less than 0.10%, those effects are small, and if it exceeds 1.20%, embrittlement is caused and weldability is also lowered, so the content was limited to 0.10 to 1.20%.
[0034]
Mn: Mn is an element that contributes to high strength by lowering the pearlite transformation temperature and improving hardenability. However, if it is less than 0.40%, the effect is small, and if it exceeds 1.40%, a martensite structure is easily generated in the segregated portion, which is not preferable.
[0035]
N: N is an element necessary for promoting the formation of pearlite transformation nuclei from austenite grain boundaries, and for that purpose, 0.006 % or more is necessary. However, if N exceeds 0.03%, a high temperature embrittlement phenomenon occurs, and an internal crack in the steel material in casting occurs, which is not preferable.
[0036]
Mo: Mo is an element necessary for suppressing the pearlite transformation rate and miniaturizing the pearlite block size. When Mo is less than 0.006 %, this effect is small. When the content exceeds 0.07%, the pearlite transformation rate excessively decreases in the segregated portion of Mo even when the above-described K value is within the proper range. It is not preferable because bainite and martensite are generated in the pearlite structure.
[0037]
Furthermore, in the present invention, in addition to the above components, S, V, Nb, Ti, Al, Mg, Ca, Ni, Cu, Cr, and B are added as necessary to improve the toughness of the ferrite base and the rail rolling material. High toughness can be obtained by refining austenite grains during heating or austenite grains during rolling, and higher strength and high toughness can be obtained by accelerated cooling in the cooling process. The reason for limiting these chemical components will be described below.
[0038]
S: S is generally known as a harmful element, but forms MnS and MgS, and these sulfides become precipitation sites for V carbonitride and Ti nitride. When these inclusions are present in the austenite grains, in addition to the grain boundaries, the transformation from the grains is promoted, and the pearlite block size after the pearlite transformation is further refined. However, if S is less than 0.002%, a sufficient number of MgS and MnS cannot be obtained, and if it exceeds 0.05%, coarse MnS is generated and the toughness and ductility are remarkably lowered.
[0039]
V: V is an element that precipitates V carbonitrides serving as pearlite transformation nuclei and refines the pearlite structure by promoting the formation of transformation nuclei from the austenite grain boundaries and within the grains. However, if V is less than 0.005%, this effect is weak and the intended purpose cannot be obtained. On the other hand, if it exceeds 0.070%, the V carbonitride becomes coarse and becomes the starting point of fracture, which is not preferable.
[0040]
Nb: Nb is heated at a low temperature during hot rolling, so that the Nb carbonitride suppresses austenite grain growth and contributes to fine graining. Also, the austenite grains after hot rolling are refined by high temperature heating / low temperature finish rolling, and the pearlite block obtained after accelerated cooling is made fine. In order to obtain this effect, 0.004% or more is necessary. However, if it exceeds 0.05%, the toughness decreases due to the formation of coarse Nb carbonitride, which is not preferable.
[0041]
Ti: Ti, like V, is an element that precipitates Ti nitride serving as a pearlite transformation nucleus and refines the pearlite structure by promoting the formation of austenite grain boundaries and transformation nuclei from within the grains. When Ti is less than 0.001%, the effect is small, and when it exceeds 0.015%, coarse Ti nitride is generated and toughness is lowered, which is not preferable.
[0042]
Al: Al suppresses the growth of austenite grains and contributes to refinement. However, if Al is less than 0.002%, this effect is not obtained, and if it exceeds 0.05%, the Al oxide becomes coarse, resulting in a decrease in toughness, and an internal fatigue starting point when used in heavy-duty railways. Since there is a danger, it is desirable that it is 0.05% or less.
[0043]
Mg: Mg precipitates Mg oxide, Mg-Al oxide, and Mg sulfide, and further serves as a nucleus for precipitation of MnS and V carbonitrides. These inclusions refine the pearlite block after pearlite transformation by the effect of promoting intragranular transformation. However, if it is less than 0.0020%, there is no effect, and if it exceeds 0.0100%, coarse inclusions are generated and the toughness is remarkably lowered, which is not preferable.
[0044]
Ca forms a sulfide, and CaS finely disperses MnS, forms a thin Mn band around MnS, contributes to the generation of pearlite transformation, and as a result, the pearlite block size is refined, It is an element effective for improving the ductility and toughness of the pearlite structure. However, if it is less than 0.015%, the effect is weak, and if added over 0.050%, a coarse oxide of Ca is generated, and the ductility and toughness of the rail are lowered.
[0045]
Ni: Ni is an element effective for improving the toughness of ferrite by dissolving in ferrite. However, when Ni is less than 0.01%, the effect is very small, and even if it exceeds 1.5%, the effect is saturated.
[0046]
Cu: Cu is an element effective for improving the toughness of ferrite by dissolving in ferrite similarly to Ni. However, when Cu is less than 0.01%, the effect is very small, and even if it exceeds 1.5%, the effect is saturated.
[0047]
Cr: Cr contributes to increasing the strength by lowering the pearlite transformation temperature, and it is effective to contain 0.1% or more from the viewpoint of preventing weld joint softening. On the other hand, if the content exceeds 1.0%, bainite and martensite are generated not only at the element segregation portion but also at the shoulder portion of the rail having a strong supercooling tendency during forced cooling, and this causes a decrease in toughness.
[0048]
B: B is an element that remarkably improves hardenability by segregating at austenite grain boundaries and delaying transformation even when added in a small amount. In order to obtain this effect, 0.0001% or more is necessary. If it exceeds 0.0050%, B carbonitride is generated and the toughness is lowered, which is not preferable.
[0049]
P is an element inevitably contained in the steel. P is preferably low because it causes embrittlement of the ferrite layer and lowers impact characteristics, and is desirably 0.015% or less.
[0050]
Similarly, O is unavoidably present in the molten steel, but if O is 0.02% or more, coarse inclusions are generated and the toughness is lowered, which is not preferable.
[0051]
【Example】
Next, an example of manufacturing a high-strength rail having high toughness manufactured according to the present invention will be described. Rails were manufactured from molten steel composed of the components shown in Table 1.
Table 2 shows the tensile test strength, elongation, and impact value at + 20 ° C. in the 2 mm U notch Charpy test when the cooling rate between 700 ° C. and 550 ° C. was changed in the range of 1 to 10 ° C./s for each steel type. The measurement results are shown.
The Charpy test piece was taken in the longitudinal direction from 3 mm below the rail top surface, and the notch position was on the top surface side. Since the notch depth is 2 mm, the position of the notch bottom corresponds to 5 mm below the rail top surface.
[0052]
The Mo and N-added steel of the present invention has a fine structure as compared with the comparative example, and the impact value is remarkably improved. Further, among the examples of the present invention, the steel material in which the amount of Mn and Cr was within the range of claim 2 did not generate fine martensite in the microsegregation part, and a uniform pearlite structure was obtained.
[0053]
The tensile test was performed on a test piece having a parallel part diameter of 6 mm and a parallel part length of 30 mm taken from a depth of 10 mm inside the rail head gauge corner. As a result, the ductility of the steel of the present invention was improved by sufficiently reducing the pearlite structure compared to the conventional steel.
[0054]
[Table 1]

[0055]
[Table 2]

[0056]
【The invention's effect】
As described above, a fine pearlite structure can be obtained by the present invention, and a pearlite rail excellent in toughness and ductility or a method for producing the pearlite rail can be provided.

Claims (8)

% By mass
C: 0.55-1.2%,
Si: 0.1-1.2%,
Mn: 0.4 to 1.4%
N: 0.006 to 0.03%,
Mo: 0.006 to 0.070%
The K value represented by the following formula (1) is 0.20 or more and less than 0.35, the balance consists of Fe and unavoidable impurities, and the hardness within 10 mm below the surface of the head section is Hv350 or more, A pearlite rail excellent in toughness and ductility, characterized in that at least the rail head has a pearlite structure.
K = Si / 24 + Mn / 6 + Cr / 5 + Mo / 2 + Ni / 40 + V / 14 (1) % By mass
C: 0.55-1.2%,
Si: 0.1-1.2%,
Mn: 0.4 to 1.2%
N: 0.006 to 0.03%,
Mo: 0.006 to 0.070%
The K value represented by the following formula (1) is 0.20 or more and less than 0.35, is composed of the balance Fe and inevitable impurities, and the L value represented by the following formula (2) is 1.2 or less. A pearlite rail excellent in toughness and ductility, characterized in that the hardness within 10 mm below the surface of the head section is Hv350 or more, and at least the rail head has a pearlite structure.
K = Si / 24 + Mn / 6 + Cr / 5 + Mo / 2 + Ni / 40 + V / 14 (1)
L = Mn + Cr (2) Steel component is more mass%,
S: 0.002 to 0.05%
The pearlite rail excellent in toughness and ductility according to claim 1 or 2, characterized in that Steel component is more mass%,
V: 0.005-0.070%,
Nb: 0.004 to 0.05%,
Ti: 0.001 to 0.015%,
Al: 0.002 to 0.050%
Mg: 0.0020 to 0.0100%,
Ca: 0.015 to 0.050%
The pearlite rail excellent in toughness and ductility according to any one of claims 1 to 3, characterized by containing one or more of the following. Steel component is more mass%,
Ni: 0.01 to 1.5%,
Cu: 0.01 to 1.5%
The pearlite rail excellent in toughness and ductility according to any one of claims 1 to 4, characterized by containing one or two of the following. Steel component is more mass%,
Cr: 0.1 to 1.0%
The pearlite rail excellent in toughness and ductility according to any one of claims 1 to 5, characterized in that Steel component is more mass%,
B: 0.0001 to 0.005%
The pearlite rail excellent in toughness and ductility according to any one of claims 1 to 6, characterized in that The steel slab comprising the component according to any one of claims 1 to 7 is formed into a rail by hot rolling, and then austenite region temperature is obtained by reheating after hot rolling, or at least the head of the rail. A method for producing a pearlite rail excellent in toughness and ductility, characterized in that the surface layer of the part is accelerated and cooled between 700 and 550 ° C. at 1 to 10 ° C./sec.