JP2002363696A - Pearlitic rail having excellent toughness and ductility and production method therefor - Google Patents
Pearlitic rail having excellent toughness and ductility and production method thereforInfo
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- JP2002363696A JP2002363696A JP2001167124A JP2001167124A JP2002363696A JP 2002363696 A JP2002363696 A JP 2002363696A JP 2001167124 A JP2001167124 A JP 2001167124A JP 2001167124 A JP2001167124 A JP 2001167124A JP 2002363696 A JP2002363696 A JP 2002363696A
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- rail
- toughness
- ductility
- pearlite
- transformation
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Abstract
Description
【０００１】[0001]
【発明の属する技術分野】本発明は、レール鋼のパーラ
イト組織を微細化して、靭性および延性の向上を図った
高強度レールおよびその製造方法に関するものである。BACKGROUND OF THE INVENTION 1. Field 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 to a method for manufacturing the same.
【０００２】[0002]
【従来の技術】鉄道輸送は輸送効率向上のための重積載
化、輸送迅速化のための高速化が進められており、レー
ルの特性に対する要求が厳しくなっている。重積載化、
高速化は特に急曲線区間におけるレール頭部の摩耗を促
進し、レール寿命を著しく短くする。このため重荷重鉄
道、高速鉄道でのレール短寿命化を改善するために、耐
摩耗性の優れた高強度レール鋼の開発、実路試験が精力
的に行われてきた。その結果、微細パーライト組織を適
用した高強度レールが急曲線区間に広く普及している。2. Description of the Related Art Rail transport is being carried out with heavy loads for improving transport efficiency and speeding up for rapid transport, and demands on rail characteristics are becoming stricter. Heavy loading,
Higher speeds promote wear of the rail head, especially in sharply curved sections, and significantly reduce rail life. Therefore, in order to improve the life of rails in heavy-load railways and high-speed railways, high-strength rail steel with excellent wear resistance and on-road tests have been vigorously conducted. As a result, high-strength rails to which a fine pearlite structure is applied are widely used in sharply curved sections.
【０００３】一方、寒冷地の鉄道では冬季にレールクラ
ック発生によるレール取替が集中しており、レール材の
靭性改善がレール寿命の延伸に必要な課題になってい
る。寒冷地でのレール鋼に対する衝撃値規格としては、
試験温度２０℃における２ｍｍＵノッチ衝撃値が２５Ｊ
／ｃｍ2 以上というロシアΓｏｃｔ規格の例がある。本
来、この衝撃値規格はロシア国内で製造されてきた焼入
れ・焼戻し法によって製造されたマルテンサイト鋼高強
度レールに適用されてきたものである。焼戻しマルテン
サイト鋼レールは、延性、靭性に優れるものの、レール
の基本特性である耐摩耗性に課題があるため、日本では
すでに需要が無くなっている。On the other hand, in railroads in cold regions, replacement of rails due to occurrence of rail cracks is concentrated in winter, and improvement in toughness of rail materials has become a necessary issue for extending rail life. As the impact value standard for rail steel in cold regions,
2mm U notch impact value at test temperature 20 ° C is 25J
/ Cm 2 or more in the Russian @oct standard. Originally, this impact value standard has been applied to a martensitic steel high-strength rail manufactured by a quenching and tempering method manufactured in Russia. Although tempered martensitic steel rails are excellent in ductility and toughness, there is a problem in abrasion resistance, which is a basic characteristic of rails, and therefore, demand in Japan has already disappeared.
【０００４】一方、パーライト鋼レールは耐摩耗性は優
れているものの、焼戻しマルテンサイト並みの衝撃値達
成は困難である。しかしながら、耐摩耗性と衝撃特性を
両立するために、これまでに以下のような方法が開発さ
れてきている。 （１）普通圧延後、一旦常温まで冷却したレールを低温
度で再加熱した後、加速冷却する方法。 （２）制御圧延によりオーステナイト粒を微細化した
後、レール頭部を加速冷却する方法。 （３）パーライト変態時にオーステナイト結晶粒界に加
え、オーステナイト結晶粒内からも変態を促進し、微細
なパーライト組織を得る方法。On the other hand, although pearlite steel rails have excellent wear resistance, it is difficult to achieve an impact value comparable to that of tempered martensite. However, in order to achieve both wear resistance and impact characteristics, the following methods have been developed so far. (1) A method in which, after ordinary rolling, a rail once cooled to room temperature is reheated at a low temperature and then accelerated cooling. (2) A method in which austenite grains are refined by controlled rolling and then the rail head is accelerated and cooled. (3) A method of obtaining a fine pearlite structure by promoting the transformation from inside the austenite crystal grains in addition to the austenite crystal boundaries at the time of pearlite transformation.
【０００５】[0005]
【発明が解決しようとする課題】上記方法の（１）で
は、例えば特開昭５５−１２５２３１号公報に記載され
ているように、通常の加熱温度よりも低い８５０℃以下
の低温度に再加熱し、オーステナイト粒を細粒化するこ
とによって靭性および延性を改善しようとするものであ
る。しかし低温度で加熱し、かつレール頭部内部まで加
熱を深めようとすると、投入熱量を下げて長時間の加熱
が必要で、生産性が低下する難点がある。In the above method (1), for example, as described in Japanese Patent Application Laid-Open No. 55-125231, reheating is performed to a low temperature of 850 ° C. or lower, which is lower than a normal heating temperature. However, it is intended to improve toughness and ductility by reducing the size of austenite grains. However, when heating at a low temperature and deepening the heating to the inside of the rail head, it is necessary to reduce the amount of heat input and to perform heating for a long time, and there is a problem that productivity is reduced.
【０００６】また上記（２）の方法は、例えば特開昭５
２−１３８４２７号公報および特開昭５２−１３８４２
８号公報に記載されているように、制御圧延によるオー
ステナイト粒の細粒化で靭性・延性の向上を図ろうとす
るものである。しかし、大きな圧下力が必要という圧延
機の装置能力、あるいはレールの断面形状の長手方向の
寸法安定性が容易に得られないという、形状制御性の観
点からの問題を含んでいる。The method (2) is disclosed in, for example,
JP-A-2-138427 and JP-A-52-13842
As described in Japanese Patent Publication No. 8 (KOKAI) No. 8, the aim is to improve the toughness and ductility by making austenite grains finer by controlled rolling. However, there is a problem from the viewpoint of shape controllability that the rolling mill needs to have a large rolling force or that the dimensional stability in the longitudinal direction of the cross-sectional shape of the rail cannot be easily obtained.
【０００７】上記（３）の方法としては、例えば特公平
６−２７９９２８号公報に記載されているように、Ｍｎ
Ｓ上に析出させたＶ炭窒化物、Ｔｉ炭窒化物を核とし
て、オーステナイト結晶粒内からのパーライト変態を促
進させる方法がある。この方法により靭性および延性に
優れたレールの製造が可能となった。しかしながら、単
にＶを添加しただけでは延性・靭性を改善する効果が得
られないばかりか、Ｖ添加量の増加に伴い、鋳造段階で
の微小割れの発生によりレール内部品質が劣化するとい
う実験事実が判明した。本発明はこのような事実を解決
し、延性・靭性の優れたレール鋼を得るものである。As the method (3), for example, as described in Japanese Patent Publication No. 6-279928, Mn
There is a method of promoting pearlite transformation from inside austenite crystal grains using V carbonitride and Ti carbonitride deposited on S as nuclei. This method has enabled the production of rails having excellent toughness and ductility. However, there is an experimental fact that not only the effect of improving ductility and toughness is not obtained by merely adding V, but also the internal quality of the rail is deteriorated due to the generation of minute cracks at the casting stage with the increase in the amount of V added. found. The present invention solves such a fact and obtains a rail steel excellent in ductility and toughness.
【０００８】[0008]
【課題を解決するための手段】本発明は寒冷地において
要求される良好な衝撃特性、延性を得るための条件を提
供するものであり、その要旨は以下のとおりである。 （１） 質量％で、 Ｃ ：０．６〜１．２％、 Ｓｉ：０．１〜１．２％、 Ｍｎ：０．１〜１．５％、 Ｖ ：０．００５〜０．０７％、 Ｎ ：０．００５〜０．０２５％、Ｐ ：０．０１５％以下 を含有し、ＶとＮの質量％の比Ｖ／Ｎが５以下であり、
少なくともレール頭部が実質パーライト組織であり、内
部品質に優れることを特徴とする、靭性および延性に優
れたレール。 （２） 質量％でさらに、 Ｃｒ：０．１〜１．０％、 Ｍｏ：０．０１〜０．５０％、 Ｎｉ：０．１〜４．０％、 Ｃｕ：０．１〜４．０％、 Ｎｂ：０．００１〜０．０５０％、Ｔｉ：０．００１〜０．０５０％、 Ｂ ：０．０００１〜０．００１５％、 Ｓ ：０．０２％以下、 Ａｌ：０．０１％以下、 Ｍｇ：０．０２％以下、 の１種または２種以上を含有することを特徴とする前記
（１）記載の靭性および延性に優れたレール。SUMMARY OF THE INVENTION The present invention provides conditions for obtaining good impact properties and ductility required in a cold region, and the gist thereof is as follows. (1) In mass%, C: 0.6 to 1.2%, Si: 0.1 to 1.2%, Mn: 0.1 to 1.5%, V: 0.005 to 0.07% , N: 0.005 to 0.025%, P: 0.015% or less, and the ratio V / N of the mass% of V and N is 5 or less,
A rail having excellent toughness and ductility, characterized in that at least the rail head has a substantially pearlite structure and excellent internal quality. (2) In mass%, Cr: 0.1 to 1.0%, Mo: 0.01 to 0.50%, Ni: 0.1 to 4.0%, Cu: 0.1 to 4.0 %, Nb: 0.001 to 0.050%, Ti: 0.001 to 0.050%, B: 0.0001 to 0.0015%, S: 0.02% or less, Al: 0.01% or less , Mg: 0.02% or less, The rail having excellent toughness and ductility according to the above (1), which comprises one or more of the following.
【０００９】（３） 前記（１）または（２）のいずれ
か記載の成分からなる圧延用鋼材を、熱間圧延でレール
に形成した後、熱間圧延まま、あるいは熱間圧延後の再
加熱によってオーステナイト域温度とし、前記レールの
少なくとも頭部を７００〜５００℃間を１〜５℃／sec
で加速冷却することを特徴とする靭性および延性に優れ
た高強度パーライト系レールの製造方法。 （４） 熱間圧延における圧延仕上げ温度を９８０℃以
下とすることを特徴とする前記（３）記載の靭性および
延性に優れた高強度パーライト系レールの製造方法。(3) A steel sheet for rolling comprising the component according to (1) or (2) is formed on a rail by hot rolling, and then hot-rolled, or reheated after hot rolling. Austenitic zone temperature by heating at least the head of the rail between 700 and 500 ° C between 1 and 5 ° C / sec.
A method for producing a high-strength pearlite-based rail having excellent toughness and ductility, characterized by accelerated cooling at a temperature. (4) The method for producing a high-strength pearlite-based rail excellent in toughness and ductility according to (3), wherein the rolling finish temperature in hot rolling is 980 ° C. or lower.
【００１０】[0010]
【発明の実施の形態】以下に本発明について説明する。
レール用鋼として通常用いられるパーライト鋼が破壊す
る際には、亀裂は結晶粒単位で屈曲して進む。結晶粒界
は亀裂伝播の抵抗となるため、結晶粒を細かくすること
で破壊に要するエネルギーが大きくなり、衝撃値は増加
される。DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below.
When pearlite steel, which is commonly used as rail steel, breaks, the crack bends and proceeds in units of crystal grains. Since the crystal grain boundary becomes a resistance to crack propagation, the energy required for destruction increases by making the crystal grains fine, and the impact value is increased.
【００１１】炭素鋼がオーステナイトからパーライト変
態する際に、変態は主にオーステナイト粒界から開始す
る。この時にオーステナイト中にフェライトと結晶格子
整合性の高い析出物があれば、それが変態核として機能
し、析出物を核とする変態が起こる。その結果、多くの
パーライトモジュール（オーステナイト中で変態が球状
に進んでいく際の球形領域）が成長し、変態完了後のパ
ーライト組織を細かくすることができる。When the carbon steel undergoes a pearlite transformation from austenite, the transformation mainly starts from austenite grain boundaries. At this time, if there is a precipitate having high crystal lattice matching with ferrite in austenite, it functions as a transformation nucleus, and transformation with the precipitate as a nucleus occurs. As a result, many pearlite modules (spherical regions when the transformation progresses spherically in austenite) grow, and the pearlite structure after the transformation is completed can be made fine.
【００１２】一般にレール鋼は、精錬−鋳造−冷却−再
加熱−熱間圧延−冷却−の工程で製造される。まず転
炉、電気炉などで精錬、成分調整された溶鋼が連続鋳造
などの方法により凝固される。鋳造された鋳片、鋼塊は
熱間圧延される際に、１２００℃以上に再加熱される。
高温に加熱された鋼材は複数の圧延機を通り、徐々にレ
ール形状に成形され、９００〜１１００℃でレール形状
に仕上げられる。圧延完了後、温度が共析点以下に下が
るとパーライト変態が起こる。パーライト変態は一般に
オーステナイト結晶粒界で開始し、成長する。In general, rail steel is produced in the steps of refining, casting, cooling, reheating, hot rolling, and cooling. First, molten steel whose components have been refined and adjusted in a converter or an electric furnace is solidified by a method such as continuous casting. The cast slabs and steel ingots are reheated to 1200 ° C. or more when hot-rolled.
The steel material heated to a high temperature passes through a plurality of rolling mills, is gradually formed into a rail shape, and is finished in a rail shape at 900 to 1100 ° C. After the completion of rolling, if the temperature falls below the eutectoid point, pearlite transformation occurs. The pearlite transformation generally starts and grows at austenite grain boundaries.
【００１３】レール製造用鋼材にＣに加え、Ｖ，Ｎが含
まれていると、鋳造後−冷却中の１０００℃付近からＶ
炭窒化物が析出する。このＶ炭窒化物は圧延前に１２０
０℃以上に再加熱されると、再び母材中に溶解する。さ
らに鋼中に溶解したＶは圧延終盤の１０００℃付近の温
度から改めて炭窒化物として析出してくる。When V and N are contained in the steel material for rail production in addition to C, the V from around 1000 ° C. after casting and during cooling.
Carbonitride precipitates. This V carbonitride is 120
When reheated to 0 ° C. or higher, it dissolves again in the base material. Further, V dissolved in the steel precipitates again as carbonitride at a temperature near 1000 ° C. at the end of rolling.
【００１４】Ｖ炭窒化物はフェライトとの結晶格子の整
合性が良く、粒界および粒内に析出したＶ炭窒化物が核
となってフェライト変態が起きやすくなる。Ｖ炭窒化物
を核としてフェライト変態が起きると、即座にセメンタ
イトが析出し、パーライト変態に移行する。Ｖ炭窒化物
を核とする多数の異なる結晶方位を持つパーライト・モ
ジュールの成長により、微細なパーライトが形成する。
その結果、優れた靭性および延性を有するレール鋼を得
ることができる。このような微細なパーライト組織は、
車輪からの衝撃的な負荷の加わりやすいレールの頭部に
少なくとも形成されている必要がある。V carbonitride has good crystal lattice consistency with ferrite, and the V carbonitride precipitated in the grain boundaries and in the grains serves as a nucleus to easily cause ferrite transformation. When ferrite transformation occurs with V carbonitride as a nucleus, cementite immediately precipitates and shifts to pearlite transformation. Fine pearlite is formed by the growth of pearlite modules having a number of different crystal orientations centered on V carbonitride.
As a result, a rail steel having excellent toughness and ductility can be obtained. Such a fine pearlite structure,
It must be formed at least on the head of the rail, which is subject to impact loads from the wheels.
【００１５】ここでさらに、熱間圧延における圧延仕上
げ温度を９８０℃以下とし、Ｖ炭窒化物が析出した時点
で圧下を加えるようにすることで、さらにパーライト組
織を微細にすることができる。このとき圧延仕上げ温度
をさらに低くすることで、複数のパス以上にわたってこ
のような効果を得ることも可能である。ただし圧延仕上
げ温度を低くしすぎると圧延が困難になるため、９００
℃以上が好ましい。The pearlite structure can be further refined by setting the rolling finish temperature in hot rolling to 980 ° C. or lower and applying reduction when V carbonitride precipitates. At this time, by further lowering the rolling finish temperature, such an effect can be obtained over a plurality of passes. However, if the rolling finishing temperature is too low, rolling becomes difficult.
C. or higher is preferred.
【００１６】一方、重荷重鉄道、高速鉄道の急曲線部で
はレール鋼は、過酷な負荷と摩擦にさらされるため、高
強度、高硬度が要求される。このような使用環境に供す
るレール鋼材には、圧延終了後のオーステナイト域温度
から直接、あるいは再加熱によりオーステナイト域温度
とした後、パーライト変態温度域である７００〜５００
℃間を加速冷却することが望ましい。加速冷却を行うと
オーステナイトがより低い温度まで過冷され、パーライ
ト変態温度が低下する。On the other hand, rail steel is required to have high strength and high hardness in a sharply curved portion of a heavy load railway or a high speed railway because the rail steel is subjected to severe load and friction. The rail steel material to be used in such a use environment has a pearlite transformation temperature range of 700 to 500, which is directly from the austenite range temperature after the end of rolling, or after reheating to the austenite range temperature.
It is desirable to accelerate cooling between ° C. When accelerated cooling is performed, the austenite is supercooled to a lower temperature, and the pearlite transformation temperature decreases.
【００１７】このように過冷度が高まると、パーライト
中のフェライト−セメンタイト層間隔が減少して強度が
増大すると共に、変態核の生成速度が増加するためパー
ライト組織を微細にする効果を得ることができる。その
結果、強度上昇に加えて靭性を向上させることができ
る。ただし、加速冷却時の冷却速度が１℃／sec 未満の
ときは必要な強度を得ることができず、５℃／sec を超
える場合はマルテンサイトが生成するため好ましくな
い。As described above, when the degree of supercooling is increased, the interval between ferrite-cementite layers in pearlite is reduced, the strength is increased, and the rate of formation of transformation nuclei is increased. Can be. As a result, the toughness can be improved in addition to the increase in strength. However, if the cooling rate during accelerated cooling is less than 1 ° C./sec, the required strength cannot be obtained, and if it exceeds 5 ° C./sec, martensite is formed, which is not preferable.
【００１８】次に、レール鋼の成分を限定した理由につ
いて述べる。成分量の％は質量％である。 Ｃ：Ｃは延性、靭性を低下させるが、レールの使用安全
性に極めて重要な強度、耐摩耗性能を決める基本的な元
素である。Ｃが０．６％未満では必要とする高強度のパ
ーライト組織が得がたい。また、１．２０％を超えると
初析セメンタイトを生成し、靭性・延性を著しく低下さ
せるため好ましくない。Next, the reasons for limiting the components of the rail steel will be described. % Of the component amount is% by mass. C: C reduces ductility and toughness, but is a basic element that determines strength and wear resistance, which are extremely important for the safety of rail use. If C is less than 0.6%, it is difficult to obtain the required high-strength pearlite structure. On the other hand, when the content exceeds 1.20%, proeutectoid cementite is formed, and the toughness and ductility are remarkably reduced.
【００１９】Ｓｉ：Ｓｉは溶鋼の脱酸材として必要で、
レール鋼の精錬には欠くことができない。また、Ｓｉは
パーライト組織中のフェライト相への固溶強化による高
強度化に加え、若干の靭性および延性改善効果がある。
しかし、０．１％未満ではその効果は少なく、１．２％
を超えると脆化をもたらし溶接接合性も低下するため好
ましくない。Si: Si is required as a deoxidizer for molten steel.
Indispensable for refining rail steel. Further, Si has a slight toughness and ductility improvement effect in addition to high strength by solid solution strengthening in the ferrite phase in the pearlite structure.
However, less than 0.1%, the effect is small, 1.2%
Exceeding this is not preferable because it causes embrittlement and also reduces weldability.
【００２０】Ｍｎ：Ｍｎは変態温度を低下させ、焼入れ
性を高めることによって高強度化に寄与する元素であ
る。また鋼中のＳと結合してＭｎＳを析出して、Ｓを無
害化するためにも欠くことができない。析出したＭｎＳ
はＶ炭窒化物の析出サイトとなり、パーライト変態時の
変態核となる。しかし、０．１％未満ではこれらの効果
が小さく、１．５％を超えると偏析部にマルテンサイト
組織を生成させ易くするため好ましくない。Mn: Mn is an element that contributes to high strength by lowering the transformation temperature and increasing hardenability. In addition, it is indispensable to combine with S in steel to precipitate MnS and detoxify S. MnS deposited
Becomes a precipitation site of V carbonitride and becomes a transformation nucleus at the time of pearlite transformation. However, if it is less than 0.1%, these effects are small, and if it exceeds 1.5%, it is not preferable because a martensite structure is easily generated in a segregated portion.
【００２１】Ｖ：ＶはＶ炭窒化物を形成するために欠く
ことができない元素である。Ｖ炭窒化物がパーライト変
態核となり、多数のパーライト・モジュールが成長する
結果、変態後のパーライト組織を微細化することができ
る。Ｖが０．００５％未満ではこの効果は弱く、延性、
靭性の改善効果は小さい。V: V is an essential element for forming V carbonitride. V carbonitride becomes a pearlite transformation nucleus and a large number of pearlite modules grow. As a result, the pearlite structure after transformation can be refined. If V is less than 0.005%, this effect is weak, ductility,
The effect of improving toughness is small.
【００２２】ここで、本発明者らはＶ，Ｎの含有量を変
化させて、組織、延靭性を調査した。図１はＣ：０．７
５％、Ｓｉ：０．５０％、Ｍｎ：０．７０％、Ｐ：０．
０１０％を含有する溶鋼にＶを０〜０．０８％、かつＮ
をＶ／Ｎ：０〜７となるよう、添加量を種々変更した鋼
片を１２５０℃に再加熱後、最終パス圧延温度１０５０
℃で圧延した後、自然冷却し、得られた試験片の試験温
度２０℃における２ｍｍＵノッチシャルピー値を測定し
た結果をＶ／Ｎとの関係で示したものである。Here, the present inventors investigated the structure and ductility by changing the contents of V and N. FIG. 1 shows C: 0.7.
5%, Si: 0.50%, Mn: 0.70%, P: 0.
0 to 0.08% V and N in molten steel containing 010%
Was reheated to 1250 ° C., and the final pass rolling temperature was 1050 ° C.
The result of measuring the 2 mm U notch Charpy value of the obtained test piece at a test temperature of 20 ° C. after rolling at a temperature of 20 ° C. and then naturally cooling is shown in relation to V / N.
【００２３】図１に示すように、Ｖ量の増加に伴い衝撃
値は向上する。この効果をより顕著に得るためには、Ｖ
は０．０１５％以上が望ましい。しかし、Ｖを多量に添
加しても効果は飽和してくるばかりか、鋳造段階での微
小割れの発生によりレール内部品質が劣化する場合があ
るため、Ｖの添加上限を０．０７％とした。一方、第１
図に示すように、Ｖ，Ｎの質量含有率の比、Ｖ／Ｎ値の
増加に伴って、衝撃特性は低下する。したがって、衝撃
値を高めるにはＶ／Ｎ値が低いほうが良く、５以下であ
ることが望ましい。As shown in FIG. 1, the impact value increases as the V amount increases. To obtain this effect more remarkably, V
Is desirably 0.015% or more. However, even if a large amount of V is added, the effect is not only saturated, but also the inside quality of the rail may be degraded due to the occurrence of minute cracks in the casting stage. Therefore, the upper limit of V addition is set to 0.07%. . Meanwhile, the first
As shown in the figure, the impact characteristics decrease with an increase in the V / N mass content ratio and the V / N value. Therefore, in order to increase the impact value, the lower the V / N value is, the better, and the V / N value is desirably 5 or less.
【００２４】Ｖ／Ｎ比が低い方が、衝撃値がよくなるの
は以下の理由によると考えられる。変態までの高温の状
態で生成するＶ析出物は窒化物であり、変態点以下の比
較的低温域では炭化物が生成すると考えられる。したが
って、Ｖ析出物をパーライト変態核として利用するため
には、変態点より高い温度で析出するＶ窒化物を利用す
る必要がある。It is considered that the lower the V / N ratio, the better the impact value is due to the following reasons. The V precipitate formed at a high temperature until the transformation is a nitride, and it is considered that carbide is formed in a relatively low temperature range below the transformation point. Therefore, in order to use V precipitates as pearlite transformation nuclei, it is necessary to use V nitrides that precipitate at a temperature higher than the transformation point.
【００２５】Ｖを増加させるとＶ窒化物の生成量が増加
し、パーライト組織の微細化が進む。しかしながらＮが
少ない材料では、オーステナイト温度域でＮが消費され
てしまうと、変態点以下でＶ炭化物が生成する。変態温
度以下で鋼中に生成する析出物は鉄の結晶格子を歪ま
せ、転移の運動を妨げる効果が大きく、強度上昇、延靭
性の低下を引き起こす、析出強化効果が大きい。When V is increased, the amount of V nitride generated increases, and the pearlite structure is refined. However, in a material with a small amount of N, if N is consumed in the austenite temperature range, V carbide is generated below the transformation point. Precipitates formed in the steel below the transformation temperature have a large effect of distorting the crystal lattice of iron and hindering the movement of the transition, causing an increase in strength and a decrease in ductility, and a large precipitation strengthening effect.
【００２６】Ｎ：ＮはＶ炭窒化物を析出するために必要
な元素であり、そのためには０．００５％以上が必要で
ある。本発明者らはＶ，Ｎ添加材は連続鋳造時に鋳片内
部に微小な割れが生じやいという実験事実を得た。この
割れはレール圧延後も鋼中に残存することがあり、レー
ル使用に供することはできない。これは、湾曲型連続鋳
造において、鋳片に矯直曲げが加えられた際に生じたと
考えられる。この高温脆化を避けるためにはＮを０．０
２５％以下に制限することが有効である。N: N is an element necessary for precipitating V carbonitride, for which 0.005% or more is required. The present inventors have obtained the experimental fact that the V and N-added materials tend to cause minute cracks inside the slab during continuous casting. This crack may remain in the steel even after the rail is rolled, and cannot be used for rail use. This is considered to have occurred when straightening was applied to the slab in the curved continuous casting. In order to avoid this high-temperature embrittlement, N is set to 0.0
It is effective to limit it to 25% or less.
【００２７】Ｐ：Ｐは鋼中に不可避に含有される元素で
あるが、多量に含有すると衝撃特性が低下する。ここで
図２はＣ：０．７５％、Ｓｉ：０．５０％、Ｍｎ：０．
７０％を含有する溶鋼に、Ｐを０〜０．０３％の範囲で
種々変更した鋼片を、１２５０℃に再加熱後、最終パス
圧延温度１０５０℃で圧延した後、放冷し、得られた試
験片の試験温度２０℃における２ｍｍＵノッチシャルピ
ー値を測定した結果を、Ｐ量との関係で示したものであ
る。図２に示すように、Ｐはフェライト層を脆化させて
衝撃特性を低下する。このため特に靭性、延性を重視す
る寒冷地向けレールでは、Ｐは低いことが好ましく、少
なくとも０．０１５％以下である必要がある。P: P is an element inevitably contained in steel, but if contained in a large amount, the impact characteristics are reduced. Here, FIG. 2 shows C: 0.75%, Si: 0.50%, Mn: 0.
In a molten steel containing 70%, a steel slab in which P was variously changed in the range of 0 to 0.03% was reheated to 1250 ° C., rolled at a final pass rolling temperature of 1050 ° C., and then allowed to cool to obtain. 2 shows a result of measuring a 2 mm U notch Charpy value of the test specimen at a test temperature of 20 ° C. in relation to a P amount. As shown in FIG. 2, P embrittles the ferrite layer and lowers impact characteristics. For this reason, P is preferably low in a rail for cold regions where importance is placed on toughness and ductility, and it is necessary that the P be at least 0.015% or less.
【００２８】さらに本発明においては、上記成分の他に
必要に応じて１種または２種以上のＣｒ，Ｍｏ，Ｎｉ，
Ｎｂ，Ｃｕ，Ｔｉ，Ｂ，Ｍｇ，Ａｌ，Ｓの添加によっ
て、フェライト地の靭性改善、レール圧延素材の加熱時
におけるオーステナイト粒の、あるいは圧延時のオース
テナイト粒の細粒化によって高靭性を得ることができ
る。また、冷却過程における加速冷却によって、より高
強度と同時に高靭性を得ることができる。これらの化学
成分を限定した理由を以下に説明する。Further, in the present invention, in addition to the above components, one or more of Cr, Mo, Ni,
Improvement of toughness of ferrite ground by adding Nb, Cu, Ti, B, Mg, Al, S, and obtaining high toughness by austenite grains during heating of rail rolling material or by austenite grains during rolling. Can be. In addition, higher strength and higher toughness can be obtained by accelerated cooling in the cooling process. The reason for limiting these chemical components will be described below.
【００２９】Ｃｒ：Ｃｒはパーライト変態温度を低下さ
せることによって高強度化に寄与すると共に、溶接継ぎ
手部軟化防止の観点で０．１％以上の含有が有効であ
る。一方、１．０％を超えて含有すると、強制冷却時に
元素偏析部のみでなく、過冷却傾向の強いレールの肩部
にベイナイトやマルテンサイトが生成し、靭性の低下を
もたらすため好ましくない。Cr: Cr contributes to an increase in strength by lowering the pearlite transformation temperature, and it is effective to contain Cr in an amount of 0.1% or more from the viewpoint of preventing the weld joint from softening. On the other hand, if the content exceeds 1.0%, bainite and martensite are formed not only in the element segregation portion during forced cooling but also in the shoulder portion of the rail where the supercooling tendency is strong, which is not preferable because it lowers the toughness.
【００３０】Ｍｏ：Ｍｏはパーライトの変態速度を抑制
し、変態温度を下げて、高強度化に寄与すると共に、パ
ーライト組織を微細化することから靭性向上に有効な元
素である。しかし、０．０１％未満では上記の効果は少
なく、また、０．５０％を超える含有量ではパーライト
変態速度が低下し過ぎ、パーライト組織中にベイナイト
やマルテンサイトを生成させ靭性低下をもたらすため好
ましくない。Mo: Mo is an element effective for suppressing the transformation speed of pearlite, lowering the transformation temperature, contributing to high strength, and improving the toughness because it refines the pearlite structure. However, if the content is less than 0.01%, the above effect is small, and if the content exceeds 0.50%, the pearlite transformation rate is excessively reduced, and bainite and martensite are generated in the pearlite structure to cause a decrease in toughness. Absent.
【００３１】Ｎｉ：Ｎｉはフェライト中に固溶し、フェ
ライトの靭性を向上させるのに有効な元素である。ただ
し、Ｎｉが０．１％未満の場合にはその効果が弱く、ま
た４．０％を超えて含有してもその効果は飽和する。Ni: Ni is a solid solution in ferrite and is an effective element for improving the toughness of ferrite. However, the effect is weak when Ni is less than 0.1%, and the effect is saturated even when the content exceeds 4.0%.
【００３２】Ｃｕ：ＣｕはＮｉと同様にフェライト中に
固溶し、フェライトの靭性を向上させるのに有効な元素
である。ただし、Ｃｕが０．１％未満の場合にはその効
果が弱く、また４．０％を超えて含有してもその効果は
飽和する。Cu: Cu, like Ni, forms a solid solution in ferrite and is an effective element for improving the toughness of ferrite. However, the effect is weak when Cu is less than 0.1%, and the effect is saturated even if it exceeds 4.0%.
【００３３】Ｎｂ：Ｎｂは熱間圧延時にＮｂ炭窒化物が
オーステナイト粒成長を抑制し細粒化に寄与する。この
効果を得るためには、Ｎｂは０．００１％以上必要であ
るが、０．０５％を超えると粗大なＮｂ炭窒化物の生成
によって靭性が低下するため好ましくない。Nb: In Nb, Nb carbonitride suppresses austenite grain growth during hot rolling and contributes to grain refinement. To obtain this effect, Nb must be 0.001% or more. However, if it exceeds 0.05%, the formation of coarse Nb carbonitride lowers the toughness, which is not preferable.
【００３４】Ｔｉ：ＴｉはＮｂと同様、Ｔｉ窒化物がオ
ーステナイト粒成長を抑制し、細粒化に寄与する。ま
た、Ｍｇ，Ｍｎ粒化物上にＴｉ窒化物として析出する
と、パーライト変態核となり、パーライト組織を微細化
する機能を持っている。しかしＴｉが０．００１％以下
ではその効果が弱く、０．０５％を超えると粗大なＴｉ
窒化物を生成し靭性が低下するため好ましくない。Ti: Ti: Ti, like Nb, Ti nitride suppresses austenite grain growth and contributes to grain refinement. Further, when precipitated as Ti nitride on Mg and Mn granules, they become pearlite transformation nuclei and have a function of refining the pearlite structure. However, if Ti is less than 0.001%, the effect is weak, and if more than 0.05%, coarse Ti
It is not preferable because nitrides are formed and toughness is reduced.
【００３５】Ｂ：Ｂは微量添加においてもオーステナイ
ト粒界に偏析し、変態を遅らせることにより焼入れ性を
著しく改善する元素である。この効果を得るためには、
Ｂは０．０００１％以上必要であり、０．００１５％を
超えると鉄の炭ホウ化物が生成し、靭性が著しく低下す
るため好ましくない。B: B is an element that segregates at austenite grain boundaries even when added in a small amount, and significantly improves hardenability by delaying transformation. To get this effect,
B is required to be 0.0001% or more, and if it exceeds 0.0015%, iron carbide boride is generated, and the toughness is remarkably reduced, which is not preferable.
【００３６】Ｓ：Ｓは鋼中に不可避的に含まれるが、Ｍ
ｎ，Ｍｇと結合して硫化物を形成し、Ｖ炭窒化物の析出
サイトとなる。これらの介在物がオーステナイト粒内に
存在すると、粒界に加えて粒内からの変態を促進し、パ
ーライト組織の微細化に貢献する。しかし、Ｓが０．０
２％を超えると粗大なＭｎＳが生成し、靭性および延性
をむしろ低下させるため好ましくない。S: S is inevitably contained in steel, but M
It combines with n and Mg to form a sulfide and serves as a precipitation site for V carbonitride. When these inclusions are present in the austenite grains, they promote transformation from the grains in addition to the grain boundaries, and contribute to the refinement of the pearlite structure. However, if S is 0.0
If it exceeds 2%, coarse MnS is generated, and the toughness and ductility are undesirably reduced.
【００３７】Ａｌ：Ａｌ2 Ｏ3 やＡｌ−Ｍｇ複合酸化物
は、ＭｎＳの析出核となる。また、Ａｌ窒化物はオース
テナイト粒の成長を抑制する効果があり、パーライト組
織の微細化に寄与する。ただしＡｌが０．１％を超える
と酸化物が粗大化し、重荷重鉄道で使用された際に内部
疲労起点となる危険性があるため、０．１％以下である
ことが望ましい。Al: Al 2 O 3 or an Al—Mg composite oxide becomes a precipitation nucleus of MnS. Further, Al nitride has an effect of suppressing the growth of austenite grains and contributes to refinement of the pearlite structure. However, if Al exceeds 0.1%, the oxide becomes coarse, and there is a risk of becoming a starting point of internal fatigue when used in heavy-load railways. Therefore, it is desirable that the content be 0.1% or less.
【００３８】Ｍｇ：ＭｇはＭｇ酸化物、Ｍｇ−Ａｌ酸化
物、Ｍｇ硫化物を析出し、さらにこれらを核としてＭｎ
Ｓ、Ｖ炭窒化物の析出核となる。これらの介在物は粒内
変態の促進効果によりパーライト変態後のパーライトブ
ロックを微細にする。しかし、０．０２％を超えると粗
大な介在物が生成し、靭性が著しく低下するため好まし
くない。Mg: Mg precipitates Mg oxide, Mg-Al oxide and Mg sulfide, and further uses these as nuclei to form Mn.
It becomes a precipitation nucleus of S, V carbonitride. These inclusions refine the pearlite block after pearlite transformation due to the effect of promoting intragranular transformation. However, if it exceeds 0.02%, coarse inclusions are formed, and the toughness is remarkably reduced, which is not preferable.
【００３９】[0039]
【実施例】（実施例１）本発明の実施例、およびＶ，
Ｎ，Ｐ含有量を変化させた比較例により、さらに詳細に
説明する。表１はその化学組成を質量％で示したもので
ある。符号Ａ１，Ｂ１に示す比較例は、Ｖ，Ｎ，Ｐ以外
の組成は符号Ａ，Ｂの実施例とそれぞれ同等である。上
記成分の鋼材から熱間圧延によりレールを製造した。(Embodiment 1) An embodiment of the present invention and V,
This will be described in more detail with reference to a comparative example in which the N and P contents are changed. Table 1 shows the chemical composition in mass%. In the comparative examples indicated by reference numerals A1 and B1, the compositions other than V, N, and P are the same as those of the embodiments of reference numerals A and B, respectively. Rails were manufactured by hot rolling from steel having the above components.
【００４０】表２は各レール鋼種について、「熱処理有
り」として、圧延後のオーステナイト温度域から７００
℃〜５００℃間の冷却速度を１〜５℃／ｓの範囲で冷却
し、引張り強度ＴＳ＝１３００ＭＰａを狙った場合、お
よび「熱処理無し」として圧延後、大気中で放冷した場
合のそれぞれについて、試験温度２０℃での２ｍｍＵノ
ッチシャルピー衝撃値、丸棒引張り試験値、レール頭部
断面における微小割れの有無の結果を示す。Table 2 shows that, for each type of rail steel, “with heat treatment” is 700 mm from the austenite temperature range after rolling.
Cooling rate in the range of 1 to 5 ° C./s at a cooling rate between 500 ° C. and 500 ° C., for each of the case where the tensile strength TS is aimed at 1300 MPa and the case where the sample is rolled as “no heat treatment” and then left to cool in air. 2 shows the results of a 2 mm U notch Charpy impact value at a test temperature of 20 ° C., a round bar tensile test value, and the presence or absence of microcracks in a rail head cross section.
【００４１】シャルピー試験片は、レール頭頂面下３ｍ
ｍの位置を試験片上面とし、レール幅方向に３列、長手
方向に４列採取し、ノッチ位置は頭頂面側とした。ノッ
チ深さは２ｍｍであるので、ノッチ底の位置はレール頭
頂面下５ｍｍに相当する。衝撃試験値は１２本の平均値
を記載した。引張試験はレール頭部ゲージコーナー表面
から内部方向１０ｍｍ位置を試験片の円心とする、平行
部直径６ｍｍ、平行部長さ３０ｍｍのＪＩＳ４号サブサ
イズ試験片で行った。頭部断面の微小割れの有無は、鏡
面研磨した断面試料を塩酸エッチングして観察した。The Charpy test piece was 3 m below the top of the rail head.
The position of m was taken as the upper surface of the test piece, and three rows in the rail width direction and four rows in the longitudinal direction were sampled, and the notch position was on the top side. Since the notch depth is 2 mm, the position of the notch bottom corresponds to 5 mm below the rail top surface. As the impact test value, an average value of 12 pieces was described. The tensile test was performed using a JIS No. 4 sub-size test piece having a parallel part diameter of 6 mm and a parallel part length of 30 mm, with the center of the test piece being 10 mm inward from the surface of the rail head gauge corner. The presence or absence of microcracks in the head section was observed by etching the mirror-polished section sample with hydrochloric acid.
【００４２】表２に示すように、Ｖ，Ｎ量、Ｖ／Ｎ比が
適正な本発明鋼は、多数のＶ炭窒化物を核としてパーラ
イト変態が進んだ結果、微細なパーライト組織が得ら
れ、またＰ値も低いため、良好な衝撃値、伸び値が得ら
れた。特に熱処理を行った場合は、Γｏｃｔ規格である
２５Ｊ／ｃｍ2 を大きく超える良好な衝撃値が得られて
いる。As shown in Table 2, in the steel of the present invention having an appropriate V, N amount and V / N ratio, a fine pearlite structure was obtained as a result of the progress of pearlite transformation with many V carbonitrides as nuclei. Also, since the P value was low, good impact value and elongation value were obtained. In particular, when the heat treatment is performed, a good impact value that greatly exceeds the 25 octet standard of 25 J / cm 2 is obtained.
【００４３】一方、比較例の鋼は本発明例に比較して衝
撃値、伸び値が顕著に低下した。この理由は、比較例Ａ
１はＶが添加されていないためＶ炭窒化物が生成せず、
また比較例Ｂ１はＮが少ないため、Ｖ炭窒化物の生成量
が少ないため、パーライト変態核生成が促進されず、組
織が粗くなったためである。また、本発明例Ｂにおいて
圧延仕上げ温度を１０００℃とした例では、衝撃値や全
伸びなどに若干の低下が見られた。On the other hand, the steel of the comparative example had significantly lower impact value and elongation value than the inventive example. The reason for this is that Comparative Example A
No. 1 did not generate V carbonitride because V was not added,
Further, in Comparative Example B1, since the amount of V carbonitride was small because N was small, generation of pearlite transformation nuclei was not promoted, and the structure became coarse. In Example B of the present invention, when the rolling finishing temperature was 1000 ° C., a slight decrease in impact value, total elongation, and the like was observed.
【００４４】（実施例２）表３に示す化学組成の鋼材か
ら、実施例１と同様に熱間圧延によりレールを製造し、
試験を行った。表４に示すように、Ｖ，Ｎ量、Ｖ／Ｎ比
が適正な本発明鋼は、多数のＶ炭窒化物を核としてパー
ライト変態が進んだ結果、微細なパーライト組織が得ら
れ、また、Ｐ値も低いため、良好な衝撃値、伸び値が得
られた。(Example 2) Rails were manufactured from steel materials having the chemical compositions shown in Table 3 by hot rolling in the same manner as in Example 1.
The test was performed. As shown in Table 4, in the steel of the present invention in which the amounts of V and N and the V / N ratio are appropriate, a fine pearlite structure is obtained as a result of the progress of pearlite transformation with many V carbonitrides as nuclei. Since the P value was low, good impact values and elongation values were obtained.
【００４５】一方、比較例の鋼は本発明例に比較して衝
撃値、伸び値が顕著に低下した。この理由は、比較例Ｃ
１はＶ，Ｎ量および、Ｖ／Ｎの比率は良く、組織は微細
になったものの、Ｐが高いために延性・靭性が低下し
た。比較例Ｄ１はＶ／Ｎ比が高い例で、組織は微細化し
ていることから、Ｖ炭窒化物は析出していると考えられ
る。それにもかかわらず延性・靭性は低いのは、Ｖ／Ｎ
比が高いため変態終了までにＶ炭窒化物の析出が終了せ
ず、変態完了以後にＶ炭化物が多量に析出し、析出強化
の悪影響が顕在化したためである。比較例Ｄ２はＮが高
い例で、組織は微細化しているものの、断面内に欠陥が
残存しており、これらを起点に破壊が生じたため、延性
・靭性が低くなった。また、本発明例Ｃにおいて圧延仕
上げ温度を１０００℃とした例では、衝撃値や全伸びな
どに若干の低下が見られた。On the other hand, the steel of the comparative example had significantly reduced impact value and elongation value as compared with the inventive example. The reason for this is that Comparative Example C
In No. 1, the V and N contents and the ratio of V / N were good, and although the structure was fine, ductility and toughness were reduced due to high P. Comparative Example D1 is an example in which the V / N ratio is high, and since the structure is refined, it is considered that V carbonitride is precipitated. Nevertheless, the low ductility and toughness is due to V / N
This is because the precipitation of V carbonitride did not end by the end of the transformation because the ratio was high, and a large amount of V carbide precipitated after the completion of the transformation, and the adverse effect of precipitation strengthening became apparent. Comparative Example D2 was an example in which N was high, and although the structure was refined, defects remained in the cross section, and fracture occurred from these starting points, so that the ductility and toughness were low. Further, in Example C of the present invention where the rolling finishing temperature was set to 1000 ° C., a slight decrease in impact value, total elongation, and the like was observed.
【００４６】[0046]
【表１】 [Table 1]
【００４７】[0047]
【表２】 [Table 2]
【００４８】[0048]
【表３】 [Table 3]
【００４９】[0049]
【表４】 [Table 4]
【００５０】[0050]
【発明の効果】本発明により、オーステナイト内にＶ炭
窒化物が析出し、それを核としてパーライト変態が起こ
ることから、変態後のパーライト組織が微細になる。ま
た、Ｖ／Ｎの含有比率の制限により、変態以後のＶ炭化
物析出による析出強化の影響を防止することができる。
さらにＰを制限することにより、優れた衝撃特性、延性
を得ることができる。またＮ値の制限により、割れが無
い健全な内部品質を得ることができる。According to the present invention, V carbonitride precipitates in austenite and pearlite transformation takes place using the nucleus as a nucleus, so that the pearlite structure after transformation becomes fine. Further, by limiting the content ratio of V / N, it is possible to prevent the influence of precipitation strengthening due to precipitation of V carbide after transformation.
Further, by limiting P, excellent impact characteristics and ductility can be obtained. In addition, by limiting the N value, it is possible to obtain a sound internal quality without cracks.
【図１】Ｖ／Ｎ含有量と衝撃値の関係を示す図である。FIG. 1 is a diagram showing a relationship between a V / N content and an impact value.
【図２】Ｐ含有量と衝撃値の関係を示す図である。FIG. 2 is a diagram showing a relationship between a P content and an impact value.
───────────────────────────────────────────────────── フロントページの続き Ｆターム(参考） 4K042 AA04 BA02 CA02 CA05 CA06 CA08 CA09 CA10 CA12 DA04 DE05 DE06 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 4K042 AA04 BA02 CA02 CA05 CA06 CA08 CA09 CA10 CA12 DA04 DE05 DE06
Claims (10)
以下であり、少なくともレール頭部が実質パーライト組
織であることを特徴とする靭性および延性に優れたパー
ライト系レール。C: 0.6 to 1.2%, Si: 0.1 to 1.2%, Mn: 0.1 to 1.5%, V: 0.005 to 0.5% by mass%. 07%, N: 0.005 to 0.025%, P: 0.015% or less, and the ratio V / N of V and N by mass% is 5%.
A pearlite-based rail having excellent toughness and ductility, wherein the rail has a substantial pearlite structure at least.
１に記載の靭性および延性に優れたパーライト系レー
ル。2. The composition according to claim 1, further comprising one or two types of Cr: 0.1 to 1.0% and Mo: 0.01 to 0.50% by mass%. A pearlitic rail with excellent toughness and ductility as described.
１または２に記載の靭性および延性に優れたパーライト
系レール。3. The composition according to claim 1, further comprising one or more of Ni: 0.1 to 4.0% and Cu: 0.1 to 4.0% by mass%. 2. A pearlitic rail excellent in toughness and ductility according to 2.
１ないし３のいずれか１項に記載の靭性および延性に優
れたパーライト系レール。4. The composition according to claim 1, further comprising one or more of Nb: 0.001 to 0.050% and Ti: 0.001 to 0.050% by mass%. 3. The pearlite-based rail excellent in toughness and ductility according to any one of 3.
れかに１項に記載の靭性および延性に優れたパーライト
系レール。5. The pearlite excellent in toughness and ductility according to claim 1, further comprising B: 0.0001 to 0.0015% by mass%. System rail.
れか１項に記載の靭性および延性に優れたパーライト系
レール。6. The pearlite-based rail excellent in toughness and ductility according to any one of claims 1 to 5, further comprising S: 0.02% or less by mass%.
れか１項に記載の靭性および延性に優れたパーライト系
レール。7. A pearlite-based rail excellent in toughness and ductility according to claim 1, further comprising Al: 0.1% or less by mass%.
れか１項に記載の靭性および延性に優れたパーライト系
レール。8. The pearlite-based rail excellent in toughness and ductility according to claim 1, further comprising Mg: 0.02% or less by mass.
の成分からなる圧延用鋼材を、熱間圧延でレールに形成
した後、熱間圧延まま、あるいは熱間圧延後の加熱によ
ってオーステナイト域温度とし、前記レールの少なくと
も頭部を７００〜５００℃間を１〜５℃／sec で加速冷
却することを特徴とする靭性および延性に優れた高強度
パーライト系レールの製造方法。9. A steel sheet for rolling comprising the component according to claim 1 formed into a rail by hot rolling, and then austenitic by hot rolling as it is, or by heating after hot rolling. A method for producing a high-strength pearlitic rail excellent in toughness and ductility, characterized in that at least a head of the rail is accelerated and cooled at a temperature of 700 to 500 ° C. at a rate of 1 to 5 ° C./sec.
８０℃以下とすることを特徴とする請求項９記載の靭性
および延性に優れた高強度パーライト系レールの製造方
法。10. A rolling finishing temperature in hot rolling of 9
The method for producing a high-strength pearlite-based rail excellent in toughness and ductility according to claim 9, wherein the temperature is 80 ° C or lower.
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| JP2001167124A JP4571759B2 (en) | 2001-06-01 | 2001-06-01 | Perlite rail and manufacturing method thereof |
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Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2009108396A (en) * | 2007-10-10 | 2009-05-21 | Jfe Steel Corp | Pearlitic steel rail of high internal hardness type excellent in wear resistance, fatigue failure resistance and delayed fracture resistance, and manufacturing method therefor |
| KR101225384B1 (en) * | 2010-10-27 | 2013-01-22 | 현대제철 주식회사 | High hardness heat treated rail using cooling condition, and method for manufacturing the same |
| US8469284B2 (en) | 2009-02-18 | 2013-06-25 | Nippon Steel & Sumitomo Metal Corporation | Pearlitic rail with excellent wear resistance and toughness |
| US8747576B2 (en) | 2009-06-26 | 2014-06-10 | Nippon Steel & Sumitomo Metal Corporation | Pearlite-based high carbon steel rail having excellent ductility and process for production thereof |
| JP2015504484A (en) * | 2011-11-28 | 2015-02-12 | タタ、スティール、ユーケー、リミテッドＴａｔａ Ｓｔｅｅｌ Ｕｋ Ｌｉｍｉｔｅｄ | Rail steel with an excellent combination of wear resistance, rolling contact fatigue resistance and weldability |
| US10113219B2 (en) | 2014-06-24 | 2018-10-30 | Yanshan University | Nano-pearlite rail and process for manufacturing same |
| CN113403521A (en) * | 2021-05-07 | 2021-09-17 | 青岛特殊钢铁有限公司 | Production method of wire rod for 2100 MPa-level alloy anticorrosive coating steel wire |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CA3108681C (en) * | 2018-09-10 | 2023-03-21 | Nippon Steel Corporation | Rail and method of manufacturing rail |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2000129397A (en) * | 1998-10-30 | 2000-05-09 | Nkk Corp | Pearlite type rail excellent in wear resistance and ductility |
| JP2000345296A (en) * | 1999-05-31 | 2000-12-12 | Nippon Steel Corp | Pearlitic rail excellent in wear resistance and resistance to internal fatigue damage, and its manufacture |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH06279928A (en) * | 1993-03-29 | 1994-10-04 | Nippon Steel Corp | High strength rail excellent in toughness and ductility and its production |
| JP3368557B2 (en) * | 1994-10-07 | 2003-01-20 | 新日本製鐵株式会社 | High strength rail with excellent ductility and toughness and its manufacturing method |
-
2001
- 2001-06-01 JP JP2001167124A patent/JP4571759B2/en not_active Expired - Fee Related
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2000129397A (en) * | 1998-10-30 | 2000-05-09 | Nkk Corp | Pearlite type rail excellent in wear resistance and ductility |
| JP2000345296A (en) * | 1999-05-31 | 2000-12-12 | Nippon Steel Corp | Pearlitic rail excellent in wear resistance and resistance to internal fatigue damage, and its manufacture |
Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2009108396A (en) * | 2007-10-10 | 2009-05-21 | Jfe Steel Corp | Pearlitic steel rail of high internal hardness type excellent in wear resistance, fatigue failure resistance and delayed fracture resistance, and manufacturing method therefor |
| US8469284B2 (en) | 2009-02-18 | 2013-06-25 | Nippon Steel & Sumitomo Metal Corporation | Pearlitic rail with excellent wear resistance and toughness |
| US8747576B2 (en) | 2009-06-26 | 2014-06-10 | Nippon Steel & Sumitomo Metal Corporation | Pearlite-based high carbon steel rail having excellent ductility and process for production thereof |
| KR101225384B1 (en) * | 2010-10-27 | 2013-01-22 | 현대제철 주식회사 | High hardness heat treated rail using cooling condition, and method for manufacturing the same |
| JP2015504484A (en) * | 2011-11-28 | 2015-02-12 | タタ、スティール、ユーケー、リミテッドＴａｔａ Ｓｔｅｅｌ Ｕｋ Ｌｉｍｉｔｅｄ | Rail steel with an excellent combination of wear resistance, rolling contact fatigue resistance and weldability |
| US10113219B2 (en) | 2014-06-24 | 2018-10-30 | Yanshan University | Nano-pearlite rail and process for manufacturing same |
| CN113403521A (en) * | 2021-05-07 | 2021-09-17 | 青岛特殊钢铁有限公司 | Production method of wire rod for 2100 MPa-level alloy anticorrosive coating steel wire |
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|---|---|
| JP4571759B2 (en) | 2010-10-27 |
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