JP3081116B2 - High wear resistant rail with pearlite metal structure - Google Patents
High wear resistant rail with pearlite metal structureInfo
- Publication number
- JP3081116B2 JP3081116B2 JP06244440A JP24444094A JP3081116B2 JP 3081116 B2 JP3081116 B2 JP 3081116B2 JP 06244440 A JP06244440 A JP 06244440A JP 24444094 A JP24444094 A JP 24444094A JP 3081116 B2 JP3081116 B2 JP 3081116B2
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- Japan
- Prior art keywords
- rail
- pearlite
- steel
- rolling
- particle size
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
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Description
【０００１】[0001]
【産業上の利用分野】本発明は、鉄道その他産業機械用
として使用される強度と耐摩耗性に優れた高炭素のパー
ライト組織を呈した鋼に延・靱性を付与した高耐摩耗レ
ール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 wear-resistant rail which is used for railways and other industrial machines and which has high strength and wear resistance and has a high carbon pearlite structure and is provided with ductility and toughness. It is.
【０００２】[0002]
【従来の技術】高炭素でパーライトの金属組織を呈した
鋼は強度が高く、耐摩耗性が良好なことから構造材料と
して使用され、中でも鉄道車両の重量増加に伴う高軸荷
重化や高速輸送化に対応したレールとして特に多く使用
されている。2. Description of the Related Art High carbon steel having a pearlitic metal structure is used as a structural material because of its high strength and good wear resistance. It is used particularly often as a rail corresponding to the development.
【０００３】このような鋼材の製造法としては、例えば
特開昭５５−２７６８号公報には「パーライト組織を呈
しやすい特定成分の鋼をＡｃ3 点以上の加熱温度から冷
却して４５０〜６００℃の温度で恒温変態させて、微細
パーライト組織を生成させる硬質レールの製造法」が、
また特開昭５８−２２１２２９号公報には「Ｃ：０．６
５〜０．８５％、Ｍｎ：０．５〜２．５％を含有して高
温度の熱を保有したレールを急冷し、レールまたはレー
ルヘッドの組織を微細なパーライトとして耐摩耗性を改
善したレールの熱処理法」が開示され、さらに特開昭５
９−１３３３２２号公報は「安定してパーライト組織が
得られる特定成分の圧延レールを、Ａｒ3 点以上の温度
から特定温度の溶融塩浴中に浸漬して、レール頭頂部表
面下約１０mmまでにＨｖ＞３５０の硬さをもつ微細なパ
ーライト組織を呈するレールの熱処理方法」が開示され
ているごとく、高性能なレールを得るための多くの技術
が知られている。[0003] As a method for producing such a steel material, for example, Japanese Patent Application Laid-Open No. 55-2768 discloses that a steel having a specific component which easily exhibits a pearlite structure is cooled from a heating temperature of three or more Ac to 450 to 600 ° C. A method of manufacturing a hard rail that transforms at a constant temperature to generate a fine pearlite structure,
Japanese Patent Application Laid-Open No. 58-221229 discloses "C: 0.6.
The rail containing 5 to 0.85% and Mn: 0.5 to 2.5% and having high temperature heat was quenched to improve the wear resistance by making the structure of the rail or the rail head fine pearlite. Rail heat treatment method "
Japanese Patent Application Laid-Open No. 9-133322 discloses that a rolling rail of a specific component capable of stably obtaining a pearlite structure is immersed in a molten salt bath at a specific temperature from a temperature of 3 or more Ar to a height of about 10 mm below the surface of the rail top. Many techniques for obtaining high-performance rails are known, as disclosed in "Heat treatment method for rail exhibiting fine pearlite structure having hardness of Hv>350".
【０００４】しかしながら、パーライト鋼の強度や耐摩
耗性は熱処理や合金元素の添加によって所要の規格品が
容易に得られるとは言え、共析点以上の炭素を含有する
鋼においてはオーステナイト粒界にセメンタイトが生成
し、延性・靭性を著しく低下させ、例えばＪＩＳ４号引
張試験での伸び値が１０％未満、あるいはＪＩＳ３号Ｕ
ノッチシャルピー試験での常温試験値で１０J/cm2 未満
である。このように延性・靱性の低い鋼を繰り返し荷重
や振動の懸かる分野で構造部材として使用した場合、微
小な初期欠陥や疲労き裂から低応力脆性破壊を引き起こ
す懸念があった。[0004] However, it can be said that the strength and wear resistance of pearlite steel can be easily obtained by heat treatment or addition of alloying elements. However, in steels containing carbon above the eutectoid point, the austenitic grain boundaries can be obtained. Cementite is formed, significantly reducing ductility and toughness. For example, the elongation value in a JIS No. 4 tensile test is less than 10%, or JIS No. 3 U
It is less than 10 J / cm 2 as a normal temperature test value in a notch Charpy test. When such low ductility and toughness steel is used as a structural member in a field where repeated loads and vibrations are applied, there is a concern that low stress brittle fracture may be caused by minute initial defects and fatigue cracks.
【０００５】[0005]
【発明が解決しようとする課題】本発明は上記した問題
点を解消しようとするものであり、耐摩耗性を向上させ
るに有効な鋼の炭素量を共析点以上にし、その際、問題
となる鋼の延性・靭性の低下を防止するための、鋼成分
やパーライト結晶粒制御等の手段を講じて、延・靭性を
具備した高耐摩耗レールを提供することを目的とする。DISCLOSURE OF THE INVENTION The present invention is intended to solve the above-mentioned problems, and makes the carbon content of steel effective for improving wear resistance equal to or higher than the eutectoid point. It is an object of the present invention to provide a highly wear-resistant rail having ductility and toughness by taking measures such as controlling steel components and pearlite crystal grains in order to prevent a decrease in ductility and toughness of the resulting steel.
【０００６】[0006]
【課題を解決するための手段】本発明者らは、パーライ
ト組織による耐摩耗性の向上を図る場合、共析点以上の
過共析炭素にすると耐摩耗性が著しく向上することを知
見した。図１に共析点以上の鋼と共析点以下の鋼の耐摩
耗性の差を、横軸に硬さ、縦軸にころがり接触下での一
定時間後の磨耗量の関係をとり比較した。共析点以上の
過共析鋼は低い硬さでも高い耐摩耗性を示すことがわか
る。しかしながら、先に述べたように共析点以上の炭素
量の添加は鋼の延・靭性を損なう。Means for Solving the Problems The present inventors have found that when the wear resistance is improved by the pearlite structure, the use of hypereutectoid carbon having a temperature equal to or higher than the eutectoid point significantly improves the wear resistance. Fig. 1 compares the difference in wear resistance between the steel above the eutectoid point and the steel below the eutectoid point, the hardness on the horizontal axis, and the amount of wear after a certain time under rolling contact on the vertical axis. . It can be seen that a hypereutectoid steel having a temperature equal to or higher than the eutectoid point shows high wear resistance even at a low hardness. However, as described above, the addition of a carbon content above the eutectoid point impairs the ductility and toughness of the steel.
【０００７】一般に、鋼の靱性を向上させる手段には金
属組織の細粒化つまりオーステナイト組織の細粒化や粒
内変態によって達成されるものと言われている。オース
テナイト組織の細粒化は、例えば圧延時の低温加熱、あ
るいは特開昭６３−２７７７２１号公報に開示されてい
るように制御圧延と再加熱処理の組合せ、また圧延後の
低温加熱処理などが利用されている。しかし、レールの
製造法においては、成形性確保の観点から圧延時の低温
加熱や制御圧延における低温圧延、大圧下圧延の適用が
困難な理由から、今日においても従来から低温加熱処理
法による靱性向上が図られている。ところが、この方法
も、近来の各鋼製品における省力化・生産性向上技術の
開発が進められる中で製造コストが高く、生産性も低い
などの問題があり、これらの問題の早期解決が望まれて
いる。In general, it is said that a means for improving the toughness of steel is achieved by reducing the grain size of the metal structure, that is, by reducing the grain size of the austenite structure and intragranular transformation. The grain refinement of the austenite structure is achieved by, for example, low-temperature heating during rolling, a combination of controlled rolling and reheating as disclosed in JP-A-63-277721, or low-temperature heating after rolling. Have been. However, in the rail manufacturing method, it is difficult to apply low-temperature heating during rolling, low-temperature rolling in controlled rolling, and large reduction rolling from the viewpoint of ensuring formability. Is planned. However, this method also has problems such as high manufacturing cost and low productivity in the development of labor saving and productivity improvement technologies for recent steel products, and it is desired to solve these problems early. ing.
【０００８】本発明者らは、細粒のパーライト組織を得
て靱性を向上させた鋼を製造するために、鋼成分とその
製造法から多くの実験を試みた結果、以下のことを知見
した。すなわち、レールの頭部は耐摩耗性、底部は曲げ
疲労性および延性が主として求められ、この部分を過共
析Ｃ成分としかつ細粒パーライトブロックサイズを制御
することによって、耐摩耗性と延・靭性に優れたレール
が得られることを知見し、本発明に至った。The inventors of the present invention have conducted a number of experiments on steel components and methods for producing the same in order to obtain a fine-grained pearlite structure and to improve the toughness of the steel, and have found the following. . In other words, the head of the rail is mainly required to have wear resistance and the bottom is required to have bending fatigue properties and ductility. This part is used as a hypereutectoid C component and the fine pearlite block size is controlled to provide wear resistance and ductility. The present inventors have found that a rail having excellent toughness can be obtained, and have reached the present invention.
【０００９】そして、高炭素の鋼はそのオーステナイト
状態での加工において、比較的低温で、かつ小さい圧下
量でも圧延直後に再結晶することを見いだし、小圧下の
連続圧延によって整粒の微細オーステナイト粒を得、そ
の結果、延・靭性の優れた細粒のパーライト組織が得ら
れることを知見した。It has been found that high-carbon steel is recrystallized immediately after rolling at a relatively low temperature and with a small rolling reduction in the processing in the austenitic state. Was obtained, and as a result, it was found that a fine-grained pearlite structure excellent in ductility and toughness was obtained.
【００１０】ここでパーライトブロックとは、図２に示
すように、結晶方位の同じパーライトの集合で、結晶方
位もラメラの方向も同じパーライトのコロニーの集合で
ある。なおラメラとは、パーライトを構成するフェライ
トとセメンタイトが積層した縞模様状の組織である。そ
して、該パーライトブロックがパーライト粒破壊時の破
壊単位となる。As shown in FIG. 2, a pearlite block is a set of pearlite having the same crystal orientation and a set of pearlite colonies having the same crystal orientation and lamella direction. The lamella is a striped structure in which ferrite and cementite constituting pearlite are laminated. And this pearlite block becomes a destruction unit at the time of pearlite grain destruction.
【００１１】本発明はこのような知見に基づいて構成し
たものであって、その要旨とするところは、質量％（以
下の％は質量を示す）で、 Ｃ ：０．８５超〜１．２０％、 Ｓｉ：０．１０〜１．２０％、 Ｍｎ：０．４０〜１．５０％を含有し、さらに必要に応じて、 Ｃｒ：０．０５〜２．００％、 Ｍｏ：０．０１〜０．３０％、 Ｖ ：０．０２〜０．１０％、 Ｎｂ：０．００２〜０．０１％、 Ｃｏ：０．１〜２．０％の１種または２種以上を含有し、 残部がＦｅおよび不可避的不純物からなる鋼でパーライ
ト組織を有し、レール断面内のパーライトブロック平均
粒径が、レール頭頂表面より該レール頭頂表面を起点と
して少なくとも２０mmの範囲、およびレール底面より該
レール底面を起点として少なくとも１５mmの範囲で２０
〜５０μｍ、それ以外の部位で３５〜１００μｍを呈
し、前記レールのパーライトブロック平均粒径が２０〜
５０μｍの部位における伸び値が１０％以上、Ｕノッチ
シャルピー値が１５J/cm2 以上であることを特徴とする
パーライト金属組織を呈した高耐摩耗レールである。The present invention has been made based on such knowledge, and the gist of the present invention is that the mass%
The lower% indicates mass) , and contains C: more than 0.85 to 1.20%, Si: 0.10 to 1.20%, Mn: 0.40 to 1.50%, and further required Accordingly, Cr: 0.05 to 2.00%, Mo: 0.01 to 0.30%, V: 0.02 to 0.10%, Nb: 0.002 to 0.01%, Co: 0 1 to 2.0% of one or more steels, the balance being steel consisting of Fe and unavoidable impurities, having a pearlite structure, and having a pearlite block average particle size in the rail cross section that is smaller than the rail top surface. A distance of at least 20 mm from the top surface of the rail and at least 15 mm from the bottom surface of the rail from the bottom surface of the rail.
５０50 μm, 35 to 100 μm in other parts, the average particle size of the pearlite block of the rail is 20 to
A highly wear-resistant rail having a pearlite metal structure characterized by an elongation value of 10% or more and a U-notch Charpy value of 15 J / cm 2 or more at a portion of 50 μm.
【００１２】以下、本発明について詳細に説明する。先
ず、本発明において鋼成分を上記のように限定した理由
について説明する。 Ｃ：Ｃはパーライト組織を生成させて耐摩耗性を確保す
る有効な成分であり、通常、レール鋼としては０．６０
〜０．８５％が用いられている。この時、パーライト組
織中のγ粒界に初析フェライトが生成する場合があり、
耐摩耗性の向上に加え、レール内部疲労損傷の起点抑制
の観点からも、Ｃ量は０．８５％超が必要である。一
方、炭素の増加に伴い、オーステナイト粒界の初析セメ
ンタイトの量も増加し、Ｃ量が１．２％を超えると、後
述するパーライト組織の細粒化をもってしても延性・靭
性の劣化は看過できなくなる。従って、Ｃ量を０．８５
％超〜１．２０％とした。Hereinafter, the present invention will be described in detail. First, the reason why the steel components are limited as described above in the present invention will be described. C: C is an effective component for generating a pearlite structure and ensuring wear resistance, and is usually 0.60 as a rail steel.
0.85 percent that have been found using. At this time, proeutectoid ferrite may be formed at the γ grain boundary in the pearlite structure,
From the viewpoint of improving the wear resistance and suppressing the starting point of the rail internal fatigue damage, the C content needs to be more than 0.85%. On the other hand, the amount of proeutectoid cementite in the austenite grain boundaries also increases with the increase in carbon, and if the C content exceeds 1.2%, the deterioration in ductility and toughness will occur even if the pearlite structure is refined as described below. I can't overlook it. Therefore, the amount of C is set to 0.85
% To 1.20%.
【００１３】Ｓｉ：Ｓｉはパーライト組織中のフェライ
トを強化するに有効な成分として０．１％以上を含有さ
せる。しかし１．２０％を超える含有量はマルテンサイ
ト組織を生成して鋼を脆化させる問題がある。従って、
Ｓｉ量を０．１０〜１．２０％とした。 Ｍｎ：Ｍｎはパーライト組織の強化に加え、パーライト
変態温度を低下させ、初析セメンタイトの生成を抑制す
る元素で、０．４０％より少ない含有量はその効果が小
さく、反対に１．５０％を超えるとマルテンサイト組織
を生成させ、鋼を脆化させる。従って、Ｍｎ量を０．４
０〜１．５０％とした。Si: Si contains 0.1% or more as an effective component for strengthening ferrite in the pearlite structure. However, when the content exceeds 1.20%, there is a problem that a martensite structure is generated and the steel is embrittled. Therefore,
The Si amount was 0.10 to 1.20%. Mn: Mn is an element that, in addition to strengthening the pearlite structure, lowers the pearlite transformation temperature and suppresses the formation of proeutectoid cementite. If it exceeds, a martensite structure is generated, and the steel is embrittled. Therefore, the amount of Mn is 0.4
0 to 1.50%.
【００１４】Ｃｒ：Ｃｒはパーライトの平衡変態点を上
昇させ、結果としてパーライト組織を微細にし、かつ初
析セメンタイトの生成を抑制する有効な元素であり、選
択添加を行う。０．０５％未満ではその効果が小さく、
２．０％を超える過剰な添加はマルテンサイト組織を生
成させ、鋼を脆化させる。従って、Ｃｒ量は０．０５〜
２．００％とした。Cr: Cr is an effective element that raises the equilibrium transformation point of pearlite, makes the pearlite structure finer, and suppresses the formation of proeutectoid cementite, and is selectively added. If it is less than 0.05%, the effect is small,
Excessive addition over 2.0% creates a martensitic structure and embrittles the steel. Therefore, the Cr content is 0.05 to
2.00%.
【００１５】Ｍｏ，Ｎｂ：ＭｏおよびＮｂはパーライト
の強化に有効な元素であり、選択添加を行う。それぞれ
０．０１％、０．００２％未満ではその効果が小さい。
一方、それぞれ０．３０％、０．０１％を超える添加で
は、後述するように金属組織の細粒化に効果のある圧延
中のオーステナイト粒の再結晶を抑制し、伸長粗大オー
ステナイト粒を生ぜしめ、パーライト鋼を脆化させる。
従って、Ｍｏ量を０．０１〜０．３０％、Ｎｂ量を０．
００２〜０．０１％とした。Mo, Nb: Mo and Nb are effective elements for strengthening pearlite, and are selectively added. The effect is small when it is less than 0.01% and 0.002%, respectively.
On the other hand, additions exceeding 0.30% and 0.01%, respectively, suppress the recrystallization of austenite grains during rolling, which is effective in refining the metal structure, as described later, and generate elongated coarse austenite grains. , Embrittles pearlite steel.
Therefore, the Mo amount is 0.01 to 0.30% and the Nb amount is 0.1%.
002 to 0.01%.
【００１６】Ｖ，Ｃｏ：Ｖの０．０２〜０．１％、Ｃｏ
の０．１０〜２．０％は、各成分がパーライト組織を強
化する有効な含有量であって、選択添加を行う。下限未
満の量では強化効果が小さく、また上限を超える量は強
化の効果が飽和域に達する。本発明は上記のような共析
炭素以上の炭素を含有し、かつ高炭素鋼特有のオーステ
ナイトの再結晶挙動の知見に基づいているため、必要に
応じて上記各種成分を添加しても金属組織がパーライト
を呈する範囲では何ら差し障りはない。V, Co: 0.02-0.1% of V, Co
Of 0.10 to 2.0% of each component is an effective content for strengthening the pearlite structure, and is selectively added. If the amount is less than the lower limit, the strengthening effect is small, and if the amount exceeds the upper limit, the strengthening effect reaches a saturation range. Since the present invention contains carbon above eutectoid carbon as described above, and is based on the knowledge of the recrystallization behavior of austenite specific to high carbon steel, the metallographic structure can be added even if the above various components are added as necessary. There is no hindrance in the range in which pearlite is exhibited.
【００１７】パーライトブロック平均粒径が２０〜５０
μｍとなる範囲を、レール頭頂表面より該レール頭頂表
面を起点に０〜２０mm以上、およびレール底面より該レ
ール底面を起点に０〜１５mm以上としたのは、列車の通
過によって、レール頭部に車輪との接触によって損傷問
題を起こす範囲はレール摩耗を考慮してレール頭頂表面
より２０mm未満であり、また底部に発生する引っ張り応
力が及んで損傷に影響する範囲はレール底面より１５mm
未満であることによる。The pearlite block has an average particle size of 20 to 50.
The range of μm is 0 to 20 mm or more starting from the rail top surface from the rail top surface, and 0 to 15 mm or more starting from the rail bottom surface from the rail bottom surface. The area that causes a damage problem due to contact with the wheel is less than 20 mm from the top of the rail considering the wear of the rail, and the area where the tensile stress generated at the bottom affects the damage is 15 mm from the bottom of the rail.
Because it is less than.
【００１８】上記レール頭頂表面および底面付近のパー
ライトブロック平均粒径を２０〜５０μｍの範囲とした
のは、２０μｍ未満に細粒化すると、レールの基本特性
である耐摩耗性確保に必要な硬度が得られず、５０μｍ
を超えると延性・靭性が劣化するからである。The average particle size of the pearlite block in the vicinity of the top and bottom surfaces of the rail is in the range of 20 to 50 μm. When the particle size is reduced to less than 20 μm, the hardness required for securing the wear resistance, which is the basic characteristic of the rail, is reduced. Not obtained, 50 μm
This is because ductility and toughness are deteriorated when the ratio exceeds.
【００１９】レール頭頂表面および底面付近以外の部位
のパーライトブロック平均粒径を３５〜１００μｍとし
たのは、３５μｍ未満に細粒化すると、レール母材の具
備すべき強度が得られず、１００μｍを超えるとレール
母材の延性・靭性が劣化するからである。The reason why the average particle size of the pearlite block is 35 to 100 μm in the portion other than the vicinity of the top surface and the bottom surface of the rail is that when the particle size is reduced to less than 35 μm, the strength required for the rail base material cannot be obtained. If it exceeds, the ductility and toughness of the rail base material deteriorate.
【００２０】パーライトブロック平均粒径が２０〜５０
μｍの範囲としたレールの伸びを１０％以上、Ｕノッチ
シャルピー値が１５J/cm2 以上としたのは、伸びが１０
％未満では列車通過時の伸び歪みに対応できず長期使用
によってクラック発生の懸念があり、またＵノッチシャ
ルピー値が１５J/cm2 未満ではやはり列車通過時の衝撃
に対応できず長期使用によって破壊する懸念があるから
である。The average particle size of the pearlite block is from 20 to 50.
The elongation of the rail in the range of μm was 10% or more, and the U-notch Charpy value was 15 J / cm 2 or more.
Is less than% there is concern of cracks caused by long-term use can not correspond to elongation strain at a train pass, also U-notch Charpy value is destroyed by long-term use can not also correspond to impact during a train pass is less than 15 J / cm 2 There is concern.
【００２１】次に、本発明レールは以下のような製造方
法で得られることを説明する。レール鋼の圧延では、鋳
片の粗形圧延を行った後の仕上げ圧延段階においては、
レールの成形性確保の観点から、その１パス当たりの圧
下量は断面減少率にして通常５〜３０％の比較的小さい
範囲であり、仕上げ温度は１０００℃程度である。これ
に対して、最近はより低温で圧延し、延性や靭性の改善
を目的とした制御圧延も行われている。Next, the fact that the rail of the present invention can be obtained by the following manufacturing method will be described. In the rolling of rail steel, in the finish rolling stage after the rough rolling of the slab,
From the viewpoint of ensuring the formability of the rail, the rolling reduction per pass is within a relatively small range of usually 5 to 30% in terms of cross-sectional reduction rate, and the finishing temperature is about 1000 ° C. On the other hand, recently, controlled rolling for the purpose of improving ductility and toughness has been carried out at a lower temperature.
【００２２】一般にフェライトを主体にした鋼の制御圧
延の場合は、オーステナイトの未再結晶領域まで圧延温
度を低下させ、加工オーステナイト中への歪の導入によ
り、フェライト核の増大を図り、細粒フェライトを得る
制御圧延法が採られている。しかしながら、パーライト
鋼の場合、共析変態のためパーライトの変態成長速度が
大きく、オーステナイト粒内の加工歪程度の変態核は有
効に作用せず、実質的に細粒パーライトが得られ難いこ
とがわかった。従って、整粒の細粒オーステナイト鋼を
得ることがパーライト細粒化に必要なことがわかった。In general, in the case of controlled rolling of steel mainly containing ferrite, the rolling temperature is lowered to a non-recrystallized region of austenite, strain is introduced into the processed austenite to increase ferrite nuclei, and fine-grained ferrite is formed. The controlled rolling method to obtain However, in the case of pearlite steel, the transformation growth rate of pearlite is high due to eutectoid transformation, the transformation nucleus of the degree of processing strain in austenite grains does not work effectively, and it is found that it is difficult to obtain substantially fine pearlite. Was. Therefore, it was found that obtaining fine-grained austenitic steel was necessary for reducing pearlite.
【００２３】かかる観点から、高炭素鋼のオーステナイ
トの再結晶挙動を詳細に検討した結果、低炭素鋼に比
較して低い温度まで、かつ低加工度で再結晶すること、
加工後、完全再結晶に要する時間が非常に小さい、す
なわち圧延直後に再結晶を完了すること、小さな圧下
でも連続的に加工を加えると、その都度再結晶を繰り返
すことを知見し、その結果、この圧延中の静的再結晶に
より細粒のオーステナイト粒が得られることがわかっ
た。この時、さらに仕上げ圧延機ではレール頭部の上部
とレール底部の下部はその他の部位に比較してより大き
い歪が加えられ、比較的細粒度が大きくなる。From such a viewpoint, as a result of studying the recrystallization behavior of austenite of a high carbon steel in detail, it was found that recrystallization to a lower temperature and a lower workability than that of a low carbon steel;
After processing, the time required for complete recrystallization is very small, that is, recrystallization is completed immediately after rolling, and when processing is continuously performed even under a small pressure, it is found that recrystallization is repeated each time, and as a result, It was found that fine austenite grains were obtained by static recrystallization during this rolling. At this time, in the finishing rolling mill, a larger strain is applied to the upper part of the rail head and the lower part of the rail bottom as compared with other parts, and the fine grain size becomes relatively large.
【００２４】このオーステナイトの再結晶挙動を利用し
た圧延を完了後、放冷または強度をさらに向上させる場
合は加速冷却を行うことにより、先に述べた成分範囲の
鋼で構成されたレールの金属組織中のパーライトブロッ
ク径が小さくなり、車輪と接触する頭部および曲げ応力
を受ける底部はパーライトブロック径が２０〜５０μ
ｍ、その他の部位は３５〜１００μｍの微細パーライト
組織を呈し、レールの本来具備すべき強度、耐摩耗性に
加え、高い延性・靭性を兼ね備える。After completion of the rolling utilizing the recrystallization behavior of austenite, if the steel is allowed to cool or to further improve the strength, accelerated cooling is performed to obtain the metallographic structure of the rail composed of steel in the above-described composition range. The diameter of the pearlite block inside becomes smaller, and the pearlite block diameter of the head in contact with the wheel and the bottom part subjected to bending stress is 20-50 μ
m and other parts have a fine pearlite structure of 35 to 100 μm, and have high ductility and toughness in addition to the inherent strength and wear resistance of the rail.
【００２５】ところで、パーライトはオーステナイト粒
界を起点に成長するため、パーライトブロックサイズを
微細化するにはオーステナイト粒を微細化する必要があ
り、オーステナイト温度域で鋼を熱間加工することによ
って、該オーステナイト粒の微細化を行う。このオース
テナイト粒は熱間加工毎に再結晶するため、熱間加工を
繰り返すことによりまた圧下率を大きくすることによっ
て微細化する。一方、該オーステナイト結晶粒は圧延後
短時間で粒成長を始めるため、圧延間隔が長いと結晶粒
は粗大化する。従って、パーライトブロックサイズは、
オーステナイト温度域での熱間圧延の圧下率、圧延パス
数、圧延パス間の時間等によって制御することができ
る。By the way, since pearlite grows from the austenite grain boundaries, it is necessary to make austenite grains fine in order to make the pearlite block size fine. Austenite grains are refined. Since the austenite grains are recrystallized every time hot working is performed, they are refined by repeating hot working and by increasing the rolling reduction. On the other hand, since the austenite crystal grains begin to grow in a short time after rolling, if the rolling interval is long, the crystal grains become coarse. Therefore, the perlite block size is
It can be controlled by the reduction ratio of hot rolling in the austenite temperature range, the number of rolling passes, the time between rolling passes, and the like.
【００２６】[0026]
【実施例】表１に鋼の化学成分を示す。表２は加熱条件
と仕上げ圧延条件を示す。表３は圧延後の冷却条件を示
す。表４に、表１から表３に示した鋼成分、圧延条件お
よび冷却条件を組み合わせてレールを製造した場合の、
発明レールおよび比較レールの機械的性質を示す。ここ
で磨耗量は、西原式摩耗試験機を用い、直径３０mmのリ
ング状試験片を、車輪材を相手材として、すべり率９％
の条件で５０万回ころがり接触させた後の摩耗減量を測
定した。また、パーライトブロック平均粒径は、JIS G
0552に準拠した結晶粒度試験方法で、顕微鏡視野内の線
分によって切断された結晶粒数から求めた。本発明レー
ルは耐摩耗性が著しく向上するに加え、延・靭性がほと
んど低下しないことがわかる。EXAMPLES Table 1 shows the chemical components of steel. Table 2 shows heating conditions and finish rolling conditions. Table 3 shows the cooling conditions after rolling. In Table 4, when rails were manufactured by combining steel components, rolling conditions and cooling conditions shown in Tables 1 to 3,
3 shows the mechanical properties of the inventive rail and the comparative rail. Here, the wear amount was measured by using a Nishihara type abrasion tester, using a ring-shaped test piece having a diameter of 30 mm and a wheel material as a mating material, and a slip rate of 9%.
Was measured after 500,000 times of rolling contact under the above conditions. The average particle size of the pearlite block is JIS G
It was determined from the number of crystal grains cut by a line segment in the visual field of the microscope by a crystal grain size test method according to 0552. It can be seen that the rail of the present invention has significantly improved wear resistance and almost no reduction in ductility and toughness.
【００２７】[0027]
【表１】 [Table 1]
【００２８】[0028]
【表２】 [Table 2]
【００２９】[0029]
【表３】 [Table 3]
【００３０】[0030]
【表４】 [Table 4]
【００３１】[0031]
【発明の効果】以上のように、本発明により、強度・硬
度・延性・靭性に加え、優れた耐摩耗性を併せ持つパー
ライト系レールを提供することができる。As described above, the present invention can provide a pearlitic rail having excellent wear resistance in addition to strength, hardness, ductility and toughness.
【図１】Ｃ共析点以上の鋼と以下の鋼の、硬度と磨耗量
（西原式摩耗試験機にて測定）との関係を示す図。FIG. 1 is a view showing the relationship between hardness and wear (measured by a Nishihara-type abrasion tester) of steel having a C eutectoid point or higher and steel having the C or lower elongation.
【図２】パーライト結晶粒の模式図。FIG. 2 is a schematic view of pearlite crystal grains.
───────────────────────────────────────────────────── フロントページの続き (56)参考文献 特開 昭47−7606（ＪＰ，Ａ) 特開 昭52−138427（ＪＰ，Ａ) 特開 平２−305937（ＪＰ，Ａ) 特開 平６−17135（ＪＰ，Ａ) 特開 平８−109440（ＪＰ，Ａ) 特開 昭63−277721（ＪＰ，Ａ) 特開 昭55−2768（ＪＰ，Ａ) 米国特許4486248（ＵＳ，Ａ) (58)調査した分野(Int.Cl.7，ＤＢ名) C22C 38/00 - 38/60 ────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-47-7606 (JP, A) JP-A-52-138427 (JP, A) JP-A-2-305937 (JP, A) JP-A-Heisei 6 17135 (JP, A) JP-A-8-109440 (JP, A) JP-A-63-277721 (JP, A) JP-A-55-2768 (JP, A) US Patent 4,486,248 (US, A) (58) Field surveyed (Int. Cl. 7 , DB name) C22C 38/00-38/60
Claims (2)
でパーライト組織を有し、レール断面内のパーライトブ
ロック平均粒径が、レール頭頂表面より該レール頭頂表
面を起点として少なくとも２０mmの範囲、およびレール
底面より該レール底面を起点として少なくとも１５mmの
範囲で２０〜５０μｍ、それ以外の部位で３５〜１００
μｍを呈し、前記レールのパーライトブロック平均粒径
が２０〜５０μｍの部位における伸び値が１０％以上、
Ｕノッチシャルピー値が１５J/cm2以上であることを特
徴とするパーライト金属組織を呈した高耐摩耗レール。1. A mass % of C: more than 0.85 to 1.20%, Si: 0.10 to 1.20%, Mn: 0.40 to 1.50%, the balance being Fe and Having a pearlite structure in steel consisting of unavoidable impurities, the pearlite block average particle size in the rail cross section is at least 20 mm from the rail top surface to the rail top surface, and from the rail bottom surface to the rail bottom surface. 20 to 50 μm in a range of at least 15 mm, and 35 to 100 in other portions
μm, and the elongation value at a portion where the pearlite block average particle size of the rail is 20 to 50 μm is 10% or more,
A highly wear-resistant rail having a pearlite metal structure characterized by a U-notch Charpy value of 15 J / cm 2 or more.
避的不純物からなる鋼でパーライト組織を有し、レール
断面内のパーライトブロック平均粒径が、レール頭頂表
面より該レール頭頂表面を起点として少なくとも２０mm
の範囲、およびレール底面より該レール底面を起点とし
て少なくとも１５mmの範囲で２０〜５０μｍ、それ以外
の部位で３５〜１００μｍを呈し、前記レールのパーラ
イトブロック平均粒径が２０〜５０μｍの部位における
伸び値が１０％以上、Ｕノッチシャルピー値が１５J/cm
2 以上であることを特徴とするパーライト金属組織を呈
した高耐摩耗レール。2. The composition contains, by mass %, C: more than 0.85 to 1.20%, Si: 0.10 to 1.20%, and Mn: 0.40 to 1.50%, and further contains Cr: 0%. 0.05 to 2.00%, Mo: 0.01 to 0.30%, V: 0.02 to 0.10%, Nb: 0.002 to 0.01%, Co: 0.1 to 2.0 % Of steel and the balance consisting of Fe and unavoidable impurities and having a pearlite structure, wherein the average particle size of the pearlite block in the rail cross section is determined from the rail top surface to the rail top surface. At least 20mm
And the elongation value in a region where the average pearlite block particle size of the rail is 20 to 50 μm in a range of 20 to 50 μm in a range of at least 15 mm from the bottom of the rail, and 35 to 100 μm in other regions. Is 10% or more, U-notch Charpy value is 15 J / cm
Highly wear-resistant rail exhibiting a pearlite metal structure characterized by being 2 or more.
Priority Applications (12)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP06244440A JP3081116B2 (en) | 1994-10-07 | 1994-10-07 | High wear resistant rail with pearlite metal structure |
| EP95902988.5A EP0685566B2 (en) | 1993-12-20 | 1994-12-19 | Rail of high abrasion resistance and high tenacity having pearlite metallographic structure and method of manufacturing the same |
| US08/507,352 US5658400A (en) | 1993-12-20 | 1994-12-19 | Rails of pearlitic steel with high wear resistance and toughness and their manufacturing methods |
| RU95120399A RU2107740C1 (en) | 1993-12-20 | 1994-12-19 | Railroad rail from perlitic steel with high resistance to wear and high impact strength and method of its production |
| DE69427189T DE69427189T3 (en) | 1993-12-20 | 1994-12-19 | HIGH-RESISTANCE, ABRASIVE-RESISTANT RAIL WITH PERLIT STRUCTURE AND METHOD FOR THE PRODUCTION THEREOF |
| KR1019950703473A KR100186793B1 (en) | 1993-12-20 | 1994-12-19 | Rails of pearlitic steel with high wear resistance and toughness and their manufacturing method |
| CN94191249A CN1041443C (en) | 1993-12-20 | 1994-12-19 | Rail of high abrasion resistance and high tenacity having pearlite metalographic structure and method of manufacturing the same |
| PCT/JP1994/002137 WO1995017532A1 (en) | 1993-12-20 | 1994-12-19 | Rail of high abrasion resistance and high tenacity having pearlite metallographic structure and method of manufacturing the same |
| CA002154779A CA2154779C (en) | 1993-12-20 | 1994-12-19 | Rails of pearlitic steel with high wear resistance and toughness and their manufacturing methods |
| AU12013/95A AU680976B2 (en) | 1993-12-20 | 1994-12-19 | Rail of high abrasion resistance and high tenacity having pearlite metallographic structure and method of manufacturing the same |
| AT95902988T ATE201054T1 (en) | 1993-12-20 | 1994-12-19 | HIGH-STRENGTH, ABRASION-RESISTANT RAIL WITH PEARLITE STRUCTURE AND METHOD FOR THE PRODUCTION THEREOF |
| BR9406250A BR9406250A (en) | 1993-12-20 | 1994-12-19 | Perlitic steel rails with high wear resistance and toughness and their manufacturing methods |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP06244440A JP3081116B2 (en) | 1994-10-07 | 1994-10-07 | High wear resistant rail with pearlite metal structure |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH08109439A JPH08109439A (en) | 1996-04-30 |
| JP3081116B2 true JP3081116B2 (en) | 2000-08-28 |
Family
ID=17118691
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP06244440A Expired - Lifetime JP3081116B2 (en) | 1993-12-20 | 1994-10-07 | High wear resistant rail with pearlite metal structure |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP3081116B2 (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2007111285A1 (en) * | 2006-03-16 | 2007-10-04 | Jfe Steel Corporation | High-strength pearlite rail with excellent delayed-fracture resistance |
| JP2007277716A (en) * | 2006-03-16 | 2007-10-25 | Jfe Steel Kk | High-strength perlitic rail with excellent delayed-fracture resistance |
| WO2014157252A1 (en) | 2013-03-27 | 2014-10-02 | Ｊｆｅスチール株式会社 | Pearlite rail and method for manufacturing pearlite rail |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1044826C (en) | 1994-11-15 | 1999-08-25 | 新日本制铁株式会社 | Perlite rail of high abrasion resistance and method of mfg. the same |
| JP3478174B2 (en) | 1999-06-02 | 2003-12-15 | Ｊｆｅスチール株式会社 | Pearlitic steel rail with excellent wear resistance and ductility |
| CA2451147C (en) | 2002-04-05 | 2013-07-30 | Nippon Steel Corporation | Pearlitic steel rail excellent in wear resistance and ductility and method for producing the same |
| EP2135966B1 (en) | 2007-03-28 | 2017-05-03 | JFE Steel Corporation | Pearlite steel rail of high internal hardness type excellent in wear resistance and fatigue failure resistance and process for production of the same |
| BR112014031008B1 (en) * | 2012-06-14 | 2020-02-18 | Nippon Steel Corporation | RAIL RAIL AND ITS PRODUCTION METHODS |
| CN111918980A (en) | 2018-03-30 | 2020-11-10 | 杰富意钢铁株式会社 | Guide rail and method for manufacturing the same |
| JP6822575B2 (en) | 2018-03-30 | 2021-01-27 | Ｊｆｅスチール株式会社 | Rails and their manufacturing methods |
| EP4023777A4 (en) * | 2019-10-11 | 2023-03-01 | JFE Steel Corporation | Rail and method for manufacturing same |
| WO2022004247A1 (en) | 2020-06-29 | 2022-01-06 | Ｊｆｅスチール株式会社 | Rail having excellent fatigue crack propagation resistance characteristics, and method for producing same |
-
1994
- 1994-10-07 JP JP06244440A patent/JP3081116B2/en not_active Expired - Lifetime
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2007111285A1 (en) * | 2006-03-16 | 2007-10-04 | Jfe Steel Corporation | High-strength pearlite rail with excellent delayed-fracture resistance |
| JP2007277716A (en) * | 2006-03-16 | 2007-10-25 | Jfe Steel Kk | High-strength perlitic rail with excellent delayed-fracture resistance |
| AU2007230254B2 (en) * | 2006-03-16 | 2010-12-02 | Jfe Steel Corporation | High-strength pearlitic steel rail having excellent delayed fracture properties |
| CN101405419B (en) * | 2006-03-16 | 2012-06-27 | 杰富意钢铁株式会社 | High-strength pearlite rail with excellent delayed-fracture resistance |
| WO2014157252A1 (en) | 2013-03-27 | 2014-10-02 | Ｊｆｅスチール株式会社 | Pearlite rail and method for manufacturing pearlite rail |
| US10253397B2 (en) | 2013-03-27 | 2019-04-09 | Jfe Steel Corporation | Pearlitic rail and method for manufacturing pearlitic rail |
Also Published As
| Publication number | Publication date |
|---|---|
| JPH08109439A (en) | 1996-04-30 |
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