JP3832169B2 - Method for manufacturing pearlitic steel rails with excellent wear resistance and ductility - Google Patents

Description

【００３２】
【表２】

【００３３】
耐摩耗性の評価は、現状レールとして使用されている鋼種１−２９（以下基準材１と呼ぶ）の摩耗量を基準とし、この基準摩耗量に対する各鋼種の摩耗量の増減を％で示した。基準摩耗量に対して３％以上摩耗量が少ない値が得られれば十分耐摩耗性が向上したと判断した。引張試験における伸び値は１０％以上を、硬さ試験における値はＨｖ３４０〜３９９を評価基準値とした。２ｍｍＵノッチ衝撃試験は−２０℃で行い、吸収エネルギーで２０Ｊを評価基準値とした。
【００３４】
Ｃ量が低い鋼種１−１、１−２、１−３，１−２１、１−２２、１−２３、１−２４は基準材１と比較して３％以上の摩耗量の減少が認められず、耐摩耗性の向上効果は少なかった。また、本発明よりＣ量が高い鋼種１−８、１−９、１−１０，１−１８、１−１９はミクロ組織が粗い初析セメンタイトを含んでいるため耐摩耗性は優れるものの延性が低く、引張試験の伸び値は１０％未満、衝撃試験の−２０℃での吸収エネルギーは２０Ｊ未満であった。鋼種１−１１はＳｉ量が低いため、鋼種１−１３はＭｎ量が低いため、鋼種１−１４はＳｉ，Ｍｎ量が共に低いために耐摩耗性が低下している。また、鋼種１−２５はＭｏが多く、組織がベイナイトとなっているために硬さは評価基準値を満足するが耐摩耗性が低下している。鋼種１−２６は、Ｖ量が多く、析出物が粗大化するため、耐摩耗性は向上しているものの、延靭性が低下している。これに対して成分組成が本発明の範囲を満たす鋼種１−４，１−５，１−６，１−７，１−１２，１−１５，１−１６，１−１７，１−２０、１−２７，１−２８は硬さが上記したＡＲＥＭＡ規格で規定されているＨｖ＝３４０〜３９９の範囲内にあり、且つ、耐摩耗性、延靭性も上記した基準値を満足しておりいずれも優れた特性を示している。
【００３５】
図１は鋼種１−１〜１−１０の試験結果をもとに耐摩耗性、延性に及ぼすＣ含有量の影響を示したものである。本発明の範囲であるＣ含有量：０．７５〜０．８４％において優れた耐摩耗性、延性が得られることがわかる。
【００３６】
（実施例２）
表３に示す成分組成を有する供試鋼を１２８０℃に加熱し、９５０℃で熱間圧延を終了後、０．５〜３℃／ｓで５００℃以下まで冷却して製造したレールから摩耗試験片、引張試験片、硬さ試験片、衝撃試験片を採取して実施例１と同様の試験条件により評価試験を行った。
表４に耐摩耗試験、引張試験、硬さ試験、衝撃試験結果を示す。
【００３７】
【表３】

【００３８】
【表４】

【００３９】
図２には鋼種２−１〜２−１１の試験結果からＮｂ量と延性の関係を図示した。
表４、図２から明らかなように、Ｎｂ含有量が少ない鋼種２−１、２−２は延靭性が不足している。一方Ｎｂ含有量が０．０５％以上では優れた耐摩耗性と延靭性が得られた。従って、溶接性も考慮してＮｂ含有量は０．０５％以上０．５％以下とすることによって優れた耐摩耗性と延靭性、硬さが得られることがわかる。
【００４０】
しかし、Ｎｂ添加による延靭性の向上効果は０．２％以上では飽和傾向にあるので、合金添加量の経済性も考慮するとＮｂ量は０．０５％〜０．２％とするのが好ましい。
【００４１】
（実施例３）
表５に示す成分組成の供試鋼を用いて、表６に示した製造条件で製造したレールから摩耗試験片、硬さ試験片、引張試験片、衝撃試験片を採取し、実施例１と同様の試験条件により評価試験を行った。表７にその評価試験結果を示す。
【００４２】
【表５】

【００４３】
【表６】

【００４４】
【表７】

【００４５】
鋼種Ａは成分組成が本発明の範囲に属する供試鋼であり、鋼種Ｂは０．７１％Ｃを含有し、現状熱処理レールとして使用されている鋼（以下基準材２と呼ぶ）である。
【００４６】
摩耗試験は基準材２の摩耗量を基準とし、この基準摩耗量と鋼種Ａの各製造条件によって得られた摩耗量を比較し摩耗量の増減を％で示した。基準摩耗量に対して３％以上摩耗量が少ない値が得られれば十分耐摩耗性が向上したと判断した。引張試験における伸び値は１０％以上を、硬さ試験における値はＨｖ３４０〜３９９を評価基準値とした。２ｍｍＵノッチ衝撃試験は−２０℃で行い、吸収エネルギーで２０Ｊを評価基準値とした。
【００４７】
No.3-1は、圧延加熱温度が低いために圧延後のレール寸法精度が悪くレール製品として使用できなかった。No.3-2は逆に加熱温度が高すぎて圧延加熱中に鋼片に発生した傷が仕上げ圧延後もレールに残存しレール製品として使用できなかった。
【００４８】
No.3-3は圧延仕上げ温度が低いために均質なパーライト組織が得られず耐摩耗性、延性、靭性が低下した。No.3-4は圧延仕上げ温度が高すぎて、ミクロ組織が粗いパーライト組織を呈したために延性が低下した。No.3-5は冷却速度が５℃／ｓを超えているためミクロ組織はベイナイトとマルテンサイトの混合組織となり耐摩耗性が低下することとなった。No.3-6は冷却停止温度が高すぎて、ミクロ組織がラメラー間隔の細かい均質なパーライト組織が得られないために耐摩耗性、延性、靭性が低下する結果となった。一方、製造条件が全て本発明の特許請求の範囲を満足するNo.3-7, No.3-8,No.3-9,No.3-10, No.3-11は耐摩耗性、延性、靭性とも評価基準値を超える優れた値が得られた。
【００４９】
【発明の効果】
本発明によれば、高軸荷重条件下でも使用可能な耐摩耗性、延性に優れたパーライト鋼レールが提供される。
【図面の簡単な説明】
【図１】耐摩耗性、延性とＣ含有量との関係を示す図
【図２】延性とＮｂ含有量との関係を示す図[0001]
BACKGROUND OF THE INVENTION
The present invention is a pearlite steel excellent in wear resistance and toughness that achieves a long life of a rail used under severe high axial load conditions such as overseas mining railways with heavy freight cars and many sharp curves. For rails.
[0002]
[Prior art]
In mining railways (so-called high-axle heavy railways), which mainly transport ores, etc., the load applied to the axles of freight cars is much higher than that of passenger cars, and the use environment of the rails is also severe. Conventionally, steels having a pearlite structure are mainly used for rails used in such an environment from the viewpoint of emphasizing wear resistance. However, in recent years, in order to further improve the efficiency of railway transportation, the load on the freight cars has been further increased, and the amount of wear on the rails used is also increasing. Therefore, from the viewpoint of further improving the wear resistance, JP-A-8-109439 and JP-A-8-144016 describe a hypereutectoid steel having a carbon content of 0.85 to 1.20% and a pearlite structure. A contrivance has been made to increase the cementite structure ratio that ensures wear resistance. Also, in JP-A-8-246100 and JP-A-8-246101, the amount of carbon is set to 0.85 to 1.20%, and the pearlite hardness of the rail head is increased by heat treatment. Yes.
[0003]
However, rails laid on the railroad may have a temperature of 80 ° C. or higher in summer, and conversely, may be −30 ° C. or lower in winter. Due to such a large temperature difference, thermal stress due to thermal expansion and contraction is generated in the rail, and when the toughness of the rail is poor, the rail may break. In recent years, in order to increase the efficiency of laying rails, long rails (200m to 1500m in length) welded to rails are often used. As it has become even larger, rails have been required to have sufficient ductility.
[0004]
Therefore, it is difficult to reduce the toughness by the above-described method of increasing the carbon content and improving the wear resistance, and it is difficult to improve both the wear resistance and the toughness characteristics.
[0005]
[Problems to be solved by the invention]
The present invention has been made in view of such problems, and a method of manufacturing a rail that is superior in both wear resistance and ductility characteristics compared to conventional hypoeutectoid, eutectoid and hypereutectoid pearlite steel rails. Is to provide.
[0006]
[Means for Solving the Problems]
The features of the present invention for solving the above-described problems are as follows.
(1) By mass % C: 0.75 to 0.84%, Si: 0.1 to 1%, Mn: 0.4 to 2.5%, P: 0.035% or less, S: 0.035 %, Nb: 0.06 to 0.5% , the remaining Fe and the inevitable impurities steel are heated to 1100 to 1350 ° C., so that the rolling finishing temperature is 850 ° C. or more and 1050 ° C. or less. A pearlite excellent in wear resistance and ductility characterized by forming a rail material by hot rolling and then cooling the head of the rail to a temperature of 500 ° C. or less at a cooling rate of 5 ° C./s or less. Steel rail manufacturing method.
(2) C: 0.75 to 0.84% by mass , Si: 0.1 to 1%, Mn: 0.4 to 2.5%, P: 0.035% or less, S: 0.035 %, Nb: 0.06 to 0.2% contained , the remaining Fe and inevitable impurities steel is heated to 1100 to 1350 ° C. so that the rolling finishing temperature is 850 ° C. or higher and 1050 ° C. or lower. A pearlite excellent in wear resistance and ductility characterized by forming a rail material by hot rolling and then cooling the head of the rail to a temperature of 500 ° C. or less at a cooling rate of 5 ° C./s or less. Steel rail manufacturing method.
(3) In the production method of (1) or (2), a steel further containing one or more of Cr: 1.5%, Cu: 1% or less, Mo: 1% or less in mass %. A method for producing a pearlitic steel rail excellent in wear resistance and toughness, characterized by hot rolling.
(4) In the manufacturing method of (1), (2) or (3) above, the steel further containing V: 0.2% or less in mass % is hot-rolled, A method for manufacturing pearlitic steel rails with excellent ductility.
[0007]
DETAILED DESCRIPTION OF THE INVENTION
Based on the premise of a pearlite structure excellent in ductility, the present inventors finely disperse special carbides such as Nb carbide in the steel by optimizing the alloy components and the manufacturing method, so that the ductility and wear resistance are improved. A rail manufacturing method that improves both is completed.
[0008]
The details of the present invention and the reasons for limitation will be described below. First, the component composition of steel defined by the present invention will be described. In addition,% means the mass %.
[0009]
C: 0.75 to 0.84%.
C is an essential element for ensuring wear resistance, and wear resistance improves as the amount added increases. However, if it is less than 0.75%, it is difficult to obtain excellent wear resistance as compared with the conventional heat-treated pearlite steel rail. On the other hand, if it exceeds 0.85%, pro-eutectoid cementite is not formed during transformation after hot rolling. It is formed at the γ grain boundary and the ductility is significantly reduced. Therefore, the C content is in the range of 0.75 to 0.84%.
[0010]
Si: 0.1 to 1%.
Si needs to be 0.1% or more as a deoxidizing material, but if it exceeds 1%, weldability deteriorates due to the bonding force of Si with high oxygen. Accordingly, the Si amount is in the range of 0.1 to 1%.
[0011]
Mn: 0.4 to 2.5%.
Mn is an element that contributes to increasing the strength and toughness of the rail by reducing the pearlite transformation temperature and reducing the lamellar spacing of the pearlite structure. However, if 0.4% or less, a sufficient effect cannot be obtained. On the other hand, if it exceeds 2.5%, a martensitic structure due to microsegregation of the steel tends to occur, and hardening and embrittlement occur during heat treatment and welding. Since it causes deterioration, it is not preferable. Therefore, the Mn content is in the range of 0.4 to 2.5%.
[0012]
P: 0.035% or less.
If P exceeds 0.035%, the toughness deteriorates, so the content is made 0.035% or less.
[0013]
S: 0.035% or less.
S is present in the steel mainly in the form of inclusions, but if it exceeds 0.035%, the amount of inclusions increases remarkably and causes deterioration of the material, so the content is made 0.035% or less.
[0014]
Nb: 0.06 to 0.5%.
Since Nb is combined with C in the steel and precipitates finely as carbide during and after hot rolling, the hardness can be increased by precipitation strengthening to the inside of the rail head. As a result, the wear resistance is greatly improved, which greatly contributes to the extension of the rail life. Furthermore, since the carbide is finely dispersed in the material and has an effect on refining the pearlite colony, it is very effective for improving the toughness at the same carbon content. However, the effect is not exhibited effectively at 0.06% or less , and conversely, if added over 0.5%, the weldability deteriorates. Therefore, the Nb content is in the range of 0.06 to 0.5%. In addition, the range of 0.06 to 0.2% is more preferable from the viewpoint of wear resistance, the effect of improving toughness, and economical efficiency.
[0015]
One or more of Cr, Cu, Ni, and Mo can be added as necessary.
Cr: 1.5% or less.
Cr is an element for further strengthening by solid solution strengthening. However, if it exceeds 1.5%, it becomes a factor that hinders weldability due to the binding force with high oxygen of Cr, so the Cr amount is 1.5% or less (including the case of no addition). .
[0016]
Cu: 1% or less.
Cu, like Cr, is an element for further strengthening by solid solution strengthening. However, if it exceeds 1%, Cu cracking occurs, so the amount of Cu is 1% or less (including the case of no addition).
[0017]
Ni: 1% or less.
Ni is an element for further improving toughness and increasing strength by solid solution strengthening. Moreover, since Cu cracking is suppressed by complex addition with Cu, it is desirable to add Ni when Cu is added. However, if it exceeds 1%, the effect of improving strength and toughness is saturated, so the Ni content is 1% or less (however, including the case of no addition).
[0018]
Mo: 1% or less.
Mo is an element for further strengthening by solid solution strengthening, but if it exceeds 1%, a bainite structure tends to be formed and the wear resistance is lowered, so the amount of Mo is 1% or less (but not added) Including the case).
[0019]
Furthermore, V can be added.
V: 0.2% or less.
Since V is combined with C in the steel and precipitates finely as carbide during and after hot rolling, the hardness can be increased by precipitation strengthening to the inside of the rail head. As a result, the wear resistance is greatly improved, which greatly contributes to the extension of the rail life. Furthermore, since the carbide is finely dispersed in the material and has an effect on refining the pearlite colony, it is very effective for improving the toughness at the same carbon content. However, if added over 0.2%, weldability deteriorates. Therefore, the V amount is 0.2% or less.
[0020]
In addition to the above elements, it is not prohibited to contain an appropriate amount of other elements as long as the effects of the present invention are not impaired. Others are inevitable impurity elements and iron.
[0021]
Next, the manufacturing conditions of the present invention will be described.
In the present invention, the steel having the above components is heated to 1100 to 1350 ° C., and is hot-rolled so that the rolling finishing temperature is 850 ° C. or higher and 1050 ° C. or lower, and then the rail head is formed at 5 ° C. Controlled cooling to a temperature of 500 ° C. or less at a cooling rate of / s or less.
[0022]
Heating temperature: 1100-1350 ° C.
In order to roll into a complex shape such as a rail with high dimensional accuracy, it is desirable to raise the heating temperature and roll in a high temperature (recrystallization γ) region with low hot deformation resistance, so the lower limit of the heating temperature is 1100. ℃ or more. On the other hand, when heated at a temperature exceeding 1350 ° C., the surface of the steel slab is likely to be damaged, which causes a problem in the rail surface properties after finish rolling. Therefore, the upper limit of the heating temperature is 1350 ° C.
[0023]
Rolling finishing temperature: 850 to 1050 ° C.
When the rolling finishing temperature is low, rolling is performed to a non-recrystallized γ low temperature region, and not only processing strain is introduced into the γ crystal grains, but also the degree of elongation of the γ crystal grains becomes remarkable. In this case, pro-eutectoid ferrite is generated at the γ grain boundary, and the finally obtained microstructure becomes a mixed structure of ferrite and pearlite, and the wear resistance is remarkably lowered. On the other hand, when the rolling finishing temperature exceeds 1050 ° C., the γ crystal grains become coarse, so that the finally obtained pearlite colony size becomes coarse and ductility decreases. Accordingly, the rolling finishing temperature is 850 to 1050 ° C.
[0024]
Cooling rate: 5 ° C./s or less.
When the cooling rate is in the range of 5 ° C./s or less, a homogeneous pearlite structure is obtained and desired characteristics are obtained. On the other hand, when the cooling rate exceeds 5 ° C./s, a martensite structure is generated and ductility is lowered. Therefore, the cooling rate is 5 ° C./s or less.
[0025]
Cooling stop temperature: 500 ° C. or less.
In the case of chemical components and cooling rates within the scope of the present invention, the pearlite transformation start temperature is approximately 600 to 700 ° C. Therefore, in order to obtain a homogeneous pearlite structure at a cooling rate of 5 ° C./s or less, the cooling stop temperature is set to It is necessary to secure about 100 ° C. below the transformation start temperature. Therefore, the cooling stop temperature is set to 500 ° C. or lower.
[0026]
【Example】
Specific examples of the present invention will be described below.
Example 1
The test steel having the composition shown in Table 1 was heated to 1250 ° C, and after hot rolling was completed at 920 ° C, it was cooled to 500 ° C or less at 0.5 to 3 ° C / s, and the abrasion test was performed. A piece, a tensile test piece, a hardness test piece, and an impact test piece were collected and subjected to an evaluation test under the test conditions shown below.
Table 2 shows the evaluation results.
[0027]
(Abrasion test)
As for wear resistance, it is most desirable to evaluate by actually laying the rail. However, since it takes a long time for the test, use a Nishihara type wear tester that can evaluate the wear resistance in a short period of time. The actual contact condition between the rail and the wheel was evaluated by a simulated comparative test. A Nishihara-type wear test piece with an outer diameter of 30 mm was taken from the rail head, the test environment was dry, and the amount of wear after 100,000 revolutions was measured under the conditions of contact pressure: 1.4 GPa and slip rate: -10%. did. When comparing the amount of wear, the heat-treated pearlite steel rail with a C content of 0.71% is adopted as the standard steel material, and the wear resistance is improved when the wear amount is 3% or less than this steel type. It was determined.
[0028]
(Ductility evaluation test)
Tension using ASTM round bar test piece (parallel part diameter: 9mm, gauge length: 36mm), adopting the total elongation of tensile test as an index to evaluate the break due to expansion and contraction due to thermal stress of long rail end seam When elongation of 10% or more was obtained in the test, it was evaluated that no rail breakage occurred.
[0029]
(Hardness test)
Vickers hardness (Hv) was measured at a depth of 5 mm from the rail head using a Vickers hardness meter (load: 10 kgf). As the evaluation standard value of hardness, a range of Hv = 340 to 399 was adopted.
The evaluation standard values for elongation and hardness are the AREMA (American Railway Engineering and Maintenannce-of-way Associations) Standard Chapter 4 Rail section (rails for high-axle railways). This is the value specified in. In the table, Hv represents Vickers hardness.
[0030]
(Toughness evaluation test)
Regarding toughness, the toughness is sufficiently excellent if the absorbed energy when the impact test is performed at −20 ° C. using a 2 mm U notch test piece which is a required level when used in a cold region of North America satisfies 20 J or more. Judged that there is.
[0031]
[Table 1]

[0032]
[Table 2]

[0033]
The evaluation of wear resistance was based on the wear amount of steel type 1-29 (hereinafter referred to as reference material 1) currently used as a rail, and the increase / decrease in the wear amount of each steel type with respect to this reference wear amount was indicated in%. . If a value with a wear amount of 3% or more with respect to the reference wear amount was obtained, it was judged that the wear resistance was sufficiently improved. The elongation value in the tensile test was 10% or more, and the value in the hardness test was Hv 340 to 399. The 2 mm U notch impact test was performed at −20 ° C., and 20 J was used as the evaluation reference value for the absorbed energy.
[0034]
Steel types 1-1, 1-2, 1-3, 1-21, 1-22, 1-23, and 1-24 with low C content showed a 3% or more reduction in wear compared to the reference material 1. However, the effect of improving wear resistance was small. Steel types 1-8, 1-9, 1-10, 1-18, and 1-19, which have a higher C content than the present invention, contain proeutectoid cementite with a rough microstructure, and therefore have excellent wear resistance but are ductile. The elongation value of the tensile test was less than 10%, and the absorbed energy at −20 ° C. of the impact test was less than 20 J. Since steel type 1-11 has a low amount of Si, steel type 1-13 has a low amount of Mn, and steel type 1-14 has a low amount of Si and Mn, so wear resistance is low. Moreover, since steel type 1-25 has many Mo and the structure | tissue is bainite, hardness satisfies the evaluation reference value, However, Abrasion resistance is falling. Steel type 1-26 has a large amount of V, and precipitates are coarsened. Therefore, although wear resistance is improved, ductility is reduced. On the other hand, steel types 1-4, 1-5, 1-6, 1-7, 1-12, 1-15, 1-16, 1-17, 1-20 whose component composition satisfies the scope of the present invention, 1-27 and 1-28 have hardness in the range of Hv = 340 to 399 defined by the above-mentioned AREMA standard, and wear resistance and toughness satisfy the above-mentioned standard values. Also shows excellent properties.
[0035]
FIG. 1 shows the influence of the C content on the wear resistance and ductility based on the test results of steel types 1-1 to 1-10. It can be seen that excellent wear resistance and ductility can be obtained when the C content, which is the range of the present invention: 0.75 to 0.84%.
[0036]
(Example 2)
The test steel having the composition shown in Table 3 was heated to 1280 ° C, and after hot rolling was completed at 950 ° C, it was cooled to 500 ° C or less at 0.5 to 3 ° C / s, and the abrasion test was performed. A piece, a tensile test piece, a hardness test piece, and an impact test piece were collected and subjected to an evaluation test under the same test conditions as in Example 1.
Table 4 shows the results of the abrasion resistance test, tensile test, hardness test, and impact test.
[0037]
[Table 3]

[0038]
[Table 4]

[0039]
FIG. 2 shows the relationship between Nb content and ductility from the test results of steel types 2-1 to 2-11.
As is apparent from Table 4 and FIG. 2, the steel types 2-1 and 2-2 having a low Nb content are insufficient in ductility. On the other hand, when the Nb content was 0.05% or more, excellent wear resistance and ductility were obtained. Therefore, it is understood that excellent wear resistance, toughness and hardness can be obtained when the Nb content is 0.05% or more and 0.5% or less in consideration of weldability.
[0040]
However, since the effect of improving the toughness by adding Nb tends to be saturated at 0.2% or more, the Nb content is preferably 0.05% to 0.2% in consideration of the economy of the alloy addition amount.
[0041]
Example 3
Using test steels having the component compositions shown in Table 5, wear test pieces, hardness test pieces, tensile test pieces, and impact test pieces were collected from the rails manufactured under the manufacturing conditions shown in Table 6. An evaluation test was performed under the same test conditions. Table 7 shows the evaluation test results.
[0042]
[Table 5]

[0043]
[Table 6]

[0044]
[Table 7]

[0045]
Steel type A is a test steel whose composition is within the scope of the present invention, and steel type B contains 0.71% C, and is currently used as a heat-treated rail (hereinafter referred to as reference material 2).
[0046]
The wear test was based on the amount of wear of the reference material 2, and the amount of wear obtained by each production condition of steel type A was compared with the amount of wear in%. If a value with a wear amount of 3% or more with respect to the reference wear amount was obtained, it was judged that the wear resistance was sufficiently improved. The elongation value in the tensile test was 10% or more, and the value in the hardness test was Hv 340 to 399. The 2 mm U notch impact test was performed at −20 ° C., and 20 J was used as the evaluation reference value for the absorbed energy.
[0047]
No. 3-1 could not be used as a rail product due to the low rolling heating temperature, resulting in poor dimensional accuracy after rolling. On the other hand, No. 3-2 was too hot to be used, and the scratches generated on the steel slab during rolling heating remained on the rail after finishing rolling and could not be used as a rail product.
[0048]
No. 3-3 had a low rolling finish temperature, so a homogeneous pearlite structure could not be obtained and the wear resistance, ductility and toughness were reduced. In No. 3-4, the rolling finish temperature was too high, and the microstructure was rough and the pearlite structure was rough. In No. 3-5, the cooling rate exceeded 5 ° C / s, so the microstructure became a mixed structure of bainite and martensite, and the wear resistance was reduced. In No. 3-6, the cooling stop temperature was too high, and a homogeneous pearlite structure with fine lamellar spacing was not obtained, resulting in a decrease in wear resistance, ductility, and toughness. On the other hand, No.3-7, No.3-8, No.3-9, No.3-10, and No.3-11, which all satisfy the claims of the present invention, are wear resistant, Excellent values exceeding the evaluation standard value were obtained for both ductility and toughness.
[0049]
【The invention's effect】
ADVANTAGE OF THE INVENTION According to this invention, the pearlite steel rail excellent in the abrasion resistance and ductility which can be used also on a high axial load condition is provided.
[Brief description of the drawings]
FIG. 1 is a diagram showing the relationship between wear resistance, ductility and C content. FIG. 2 is a diagram showing the relationship between ductility and Nb content.

Claims (4)

C: 0.75 to 0.84% by mass , Si: 0.1 to 1%, Mn: 0.4 to 2.5%, P: 0.035% or less, S: 0.035% or less, Steel containing Nb: 0.06 to 0.5% , remaining Fe and unavoidable impurities is heated to 1100 to 1350 ° C., and the rolling finish temperature is 850 ° C. or higher and 1050 ° C. or lower. A pearlite steel rail excellent in wear resistance and ductility characterized by rolling to form a rail material and then controlling cooling the rail head to a temperature of 500 ° C. or less at a cooling rate of 5 ° C./s or less. Production method. C: 0.75 to 0.84% by mass , Si: 0.1 to 1%, Mn: 0.4 to 2.5%, P: 0.035% or less, S: 0.035% or less, Nb: 0.06 to 0.2% contained , the remainder Fe and inevitable impurities steel is heated to 1100 to 1350 ° C., and the rolling finish temperature is 850 ° C. or higher and 1050 ° C. or lower. A pearlite steel rail excellent in wear resistance and ductility characterized by rolling to form a rail material and then controlling cooling the rail head to a temperature of 500 ° C. or less at a cooling rate of 5 ° C./s or less. Production method. 3. A steel further containing one or more of Cr: 1.5%, Cu: 1% or less, and Mo: 1% or less in mass % is hot-rolled. Of pearlitic steel rails with excellent wear resistance and ductility. A method for producing a pearlitic steel rail excellent in wear resistance and toughness according to claim 1, wherein the steel further contains, in mass %, V: 0.2% or less. .

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