JPH0138853B2 - - Google Patents
Info
- Publication number
- JPH0138853B2 JPH0138853B2 JP60196980A JP19698085A JPH0138853B2 JP H0138853 B2 JPH0138853 B2 JP H0138853B2 JP 60196980 A JP60196980 A JP 60196980A JP 19698085 A JP19698085 A JP 19698085A JP H0138853 B2 JPH0138853 B2 JP H0138853B2
- Authority
- JP
- Japan
- Prior art keywords
- rail
- cooling
- rails
- hardness
- strength
- 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
Links
- 238000001816 cooling Methods 0.000 claims description 25
- 229910001566 austenite Inorganic materials 0.000 claims description 13
- 238000010438 heat treatment Methods 0.000 claims description 11
- 238000004519 manufacturing process Methods 0.000 claims description 10
- 229910052804 chromium Inorganic materials 0.000 claims description 7
- 238000000034 method Methods 0.000 claims description 7
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims description 6
- 238000005098 hot rolling Methods 0.000 claims description 6
- 229910052748 manganese Inorganic materials 0.000 claims description 5
- 238000005096 rolling process Methods 0.000 claims description 5
- 239000012535 impurity Substances 0.000 claims description 4
- 229910052758 niobium Inorganic materials 0.000 claims description 4
- 229910052719 titanium Inorganic materials 0.000 claims description 4
- 229910052720 vanadium Inorganic materials 0.000 claims description 4
- 229910052742 iron Inorganic materials 0.000 claims description 3
- 229910001562 pearlite Inorganic materials 0.000 description 9
- 229910000831 Steel Inorganic materials 0.000 description 8
- 239000010959 steel Substances 0.000 description 8
- 238000003466 welding Methods 0.000 description 8
- 239000010953 base metal Substances 0.000 description 7
- 230000000694 effects Effects 0.000 description 5
- 239000000203 mixture Substances 0.000 description 5
- 229910052757 nitrogen Inorganic materials 0.000 description 5
- 229910000851 Alloy steel Inorganic materials 0.000 description 4
- 230000000052 comparative effect Effects 0.000 description 4
- 238000009826 distribution Methods 0.000 description 4
- 229910000734 martensite Inorganic materials 0.000 description 4
- 229910045601 alloy Inorganic materials 0.000 description 3
- 239000000956 alloy Substances 0.000 description 3
- 229910052799 carbon Inorganic materials 0.000 description 3
- 239000002244 precipitate Substances 0.000 description 3
- 230000009466 transformation Effects 0.000 description 3
- 229910001567 cementite Inorganic materials 0.000 description 2
- KSOKAHYVTMZFBJ-UHFFFAOYSA-N iron;methane Chemical compound C.[Fe].[Fe].[Fe] KSOKAHYVTMZFBJ-UHFFFAOYSA-N 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- 238000002844 melting Methods 0.000 description 2
- 230000008018 melting Effects 0.000 description 2
- 238000007670 refining Methods 0.000 description 2
- 229910000859 α-Fe Inorganic materials 0.000 description 2
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
- 229910019582 Cr V Inorganic materials 0.000 description 1
- ATJFFYVFTNAWJD-UHFFFAOYSA-N Tin Chemical compound [Sn] ATJFFYVFTNAWJD-UHFFFAOYSA-N 0.000 description 1
- 230000002159 abnormal effect Effects 0.000 description 1
- 238000009825 accumulation Methods 0.000 description 1
- 238000010276 construction Methods 0.000 description 1
- 238000009749 continuous casting Methods 0.000 description 1
- 230000007423 decrease Effects 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 239000000446 fuel Substances 0.000 description 1
- 238000005469 granulation Methods 0.000 description 1
- 230000003179 granulation Effects 0.000 description 1
- 230000001771 impaired effect Effects 0.000 description 1
- 238000009434 installation Methods 0.000 description 1
- 238000012423 maintenance Methods 0.000 description 1
- 238000005065 mining Methods 0.000 description 1
- 229910052750 molybdenum Inorganic materials 0.000 description 1
- 229910052698 phosphorus Inorganic materials 0.000 description 1
- 238000004881 precipitation hardening Methods 0.000 description 1
- 238000005204 segregation Methods 0.000 description 1
- 238000010583 slow cooling Methods 0.000 description 1
- 238000005728 strengthening Methods 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
Landscapes
- Heat Treatment Of Articles (AREA)
Description
（産業上の利用分野）
本発明は、レールの品質特性に耐摩耗性、耐損
傷性と共に要求される溶接性を付与した高強度レ
ールの製造法に関するものである。
（従来の技術）
近年、海外の鉱山鉄道については高荷重化が、
また旅客鉄道については高速化が指向されてい
る。このような趨勢の中で、レールの品質特性
は、従来の耐摩耗性と耐損傷性に加え軌道保守の
合理化からロングレール化するため良好な溶接性
が重要な特性とされている。このような品質特性
の要求に対応して強度が110〜120級の高強度レー
ルが開発されている。特開昭55−125231号公報は
「Ｃ：0.55〜0.80％、Si：0.5〜1.20％、Mn：0.8〜
15％、Al：0.005〜0.05％、あるいはさらにCr：
0.20〜0.90％、Nb：0.004〜0.010％を含有する溶
接性低合金熱処理レール」、特開昭57−198216号
公報は「Ｃ：0.60〜0.85％、Si：0.1〜0.8％、
Mn：0.70〜1.5％、Cr：0.2〜0.8％あるいはさら
にNb，Ｖ，Tiの少量を選択添加した高強度レー
ル」などがある。またフラツシユ・バツト溶接、
ガス圧接など各種レール溶接法の機器や施工法が
開発されているが、中でも接合するレールの端面
を軽く接触させ、この間に大電流を通じて接触点
を集中的に加熱すると過熱溶融して火花が発生
し、所定の温度に上昇させた後、急激に圧力を加
えて圧接するフラツシユ・バツト溶接法が熱影響
部が狭い利点から一般に使用されている。
（発明が解決しようとする問題点）
しかしながら、先の例にようにレールに含有さ
れる0.8％以上のCr成分はレール製造時の高温度
からの冷却においてパーライト組織を微細化して
高強度化を図らんとするものであるが、このよう
に多量のCr成分を含有するレールは、第１図に
本発明者らの実験結果を明らかにするように溶接
継手部において高い焼入性のために脆化因子のマ
ルテンサイト組織を生成して異常な硬度を示し、
継手部の耐摩耗性、耐損傷性を著しく低下せしめ
る問題があつた。この問題を防止するためには、
溶接に際し予熱あるいは後熱処理を必要とし、溶
接能率を著しく阻害する溶接施工上に問題もあつ
た。またこのようなCrやMoなどを含有する合金
鋼レールは圧延ままで製造が可能であるため生産
効率が高いメリツトも有している。
さらに0.2〜0.8％のCrを含有する熱処理レール
では、フラツシユ・バツト溶接継手部硬を、HB
341〜388を有する母材部硬度に合せるべく添加す
るもので、高強度母材と高強度継手部の一体硬度
を形成することによつて高い耐摩耗性と波状摩耗
等の損傷抵抗性を通常の溶接条件によつて達成し
ようとするものである（特開昭55−125231号公
報）。
本発明は圧延ままあるいは簡易な熱処理法で製
造可能な低合金鋼レールの生産効率を活かし耐摩
耗性と耐損傷性が要求される高強度で溶接継手性
能にすぐれたレールの製造法を提供することを目
的としたものである。前記した従来のこの種の熱
処理レールとの大きな相違は、レール摩耗環境の
さほど厳しくない敷設領域での耐損傷性に重きを
置いた溶接性付与高強度レールの製造に関するも
のである。すなわち、従来の高強度熱処理レール
が敷設されていた急曲線区間より緩曲線区間に使
用されることを目的とした熱処理レールで、例え
ば従来の熱処理レールの頭表部硬度がHB341〜
388の領域であるのに対して、本発明レールはHB
300〜340の領域に相当するものである。
（問題点を解決するための手段）
本発明は上記の如き問題点を有利に解決したも
のであり、その要旨は、Ｃ：0.55〜0.85％、Si：
0.20〜1.20％、Mn：0.5〜1.65％、Cr：0.1〜0.19
あるいはさらにNb：0.01〜0.05％、Ｖ：0.05〜
0.20％、Ti：0.01〜0.05％の１種または２種以上
を含有し、残部が鉄および不可避的不純物からな
るレールの頭部を、熱間圧延終了後あるいは熱処
理する目的で加熱されたオーステナイト域温度か
らの冷却において、800〜450℃間を冷却速度１〜
４℃／secで冷却する溶接性を付与した高強度レ
ールの製造法である。
（発明の構成）
以下本発明について詳細に説明する。
本発明は先ずレールの成分組成を上記のように
定めた限定理由について説明する。
Ｃは高強度化およびパーライト組織生成のため
の必須元素であり、また耐摩耗性に対して一義的
に効果を示す元素であるが、0.55％未満ではオー
ステナイト粒界に耐摩耗性に好ましくない初析フ
エライトが多量に生成し、0.85％を超えるとオー
ステナイト粒界に有害な初析セメンタイトを生成
させるばかりか、熱処理層や溶接部の微小偏析部
にマルテンサイトが生成し脆化させるため0.55〜
0.85％に限定した。Siはパーライト組織中のフエ
ライトに固溶することによつて強度を上昇させ耐
摩耗性を向上させる元素であるが、脱酸元素とし
ても0.20％以上の添加が必要であり、また、1.20
％を超えると脆化が生じ溶接接合性をも減ずるの
で0.20〜1.20％に限定した。MnはＣ同様パーラ
イト変態温度を低下させ焼入性を高めることによ
つて、高強度化に寄与する元素である。しかし、
0.50％未満ではその寄与が小さくまた1.50％を超
えると偏析部にマルテンサイトを生成させやすく
するため0.50〜1.50％に限定した。Crはパーライ
ト変態開始温度を低下させ高強度化に寄与するば
かりか、パーライト中のセメンタイトを強化する
ことによつても耐摩耗性に貢献するが、さらに熱
処理レールの溶接部軟化防止に対しても欠くべか
らざる元素である。従来この溶接部軟化防止に対
してCr0.2％未満の添加は効果がないとされて来
たが、0.1％〜0.19％の添加でも十分効果が発揮
され、第２図に示すように抑制された母材部硬度
に合致した溶接継手部硬度が得られる。また0.19
％以上のCrの添加は、本発明鋼の冷却速度範囲
で得られる母材部硬度より高くなり、溶接継手部
との一体硬度を損う結果となる。
さらに本発明では、必要によつては上記の成分
の他にNb，Ｖ，Tiなどのオーステナイト粒細粒
化元素を添加することによつて、高強度化と共に
延性も確保することができる。Nbは熱間圧延時
に低温加熱することによつてNb（Ｃ，Ｎ）の析出
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、高温加熱・低温仕上圧延によつて熱
間圧延後のオーステナイト粒を細粒化し、強制冷
却後に得られるパーライト・ブロツクサイズを細
粒にする。
このとき有効なNb添加量は0.01％であり、0.05
％を超えるとNbCが生成し、かえつて脆化を招
く。従つてNbの成分範囲を0.01〜0.05％に限定し
た。ＶはNbとほぼ同様の傾向を示すが、加熱中
に析出するＶ（Ｃ，Ｎ）はNb（Ｃ，Ｎ）より溶融
温度が低いため、レール圧延時の低温加熱時のみ
初期オーステナイト粒の細粒化に寄与する。また
通常加熱によつて溶融したＶ（Ｃ，Ｎ）は冷却中
に再析出して析出硬化による強度増をもたらす。
しかしＶの0.05％以下の添加ではその析出物の数
も少なく所定の効果は期待できない。また0.20％
超のＶの添加はＶ（Ｃ，Ｎ）の粗大化によつてか
えつて脆化を生じさせる。このためＶの成分範囲
を0.05〜0.20％に限定した。Tiは析出したTi（Ｃ，
Ｎ）が高温でも溶融しないことが知られており、
通常のレール圧延加熱温度でもオーステナイトの
初期粒度を細粒化するために有効である。しかし
Nb同様Tiも0.01％以下ではその効果は小さく、
0.05％超では主としてTiNの粗大化が生じ損傷の
起点となる可能性が高いため、Tiの成分範囲を
0.01〜0.05％に限定した。この他、本発明におい
て不可避的不純物成分としてのＰ，Ｓは本発明の
目的を阻害する有害な成分で、極力低下せしめる
必要がある。
上記のような成分組成で構成されるレールは、
転炉、電気炉などが通常使用される溶解炉で溶製
された溶鋼を、造塊・分塊法あるいは連続鋳造
法、さらに熱間圧延を経て製造される。熱間圧延
を終えたレールは、圧延終了後あるいは一旦低温
度に冷却され熱処理する目的で再加熱されたオー
ステナイト域温度から冷却する。この場合の冷却
開始温度をオーステナイト域温度にしたのは均一
でかつ微細なパーライト組織を生成して耐摩耗
性、耐損傷性のレールが得られる温度である。ま
た冷却は、従来の高強度熱処理レールがHB341〜
388の範囲に対してHB300〜340の硬度範囲を目標
とするもので必然的に低加速冷却となりその冷却
制御温度範囲は800〜450℃好ましくは500℃であ
る。尚、オーステナイト域温度から冷却制御開始
温度までのこの間の冷却速度は任意な速度でよ
い。このような冷却制御温度範囲は大断面レール
から小断面レールまですべてのパーライト変態開
始から終了までを含むものであつて、この間の冷
却速度は１〜４℃／secである。この冷却速度は、
ある程度従来の高強度レールより低硬度化を目的
とするもので、１℃／sec以下の遅い冷却速度で
は目的とするHB300以上の硬度が得られない。
その反面４℃／secを越える速い速度では母材
部が高硬度を示し、化学成分によつて定まる溶接
継手部と不連続となり、溶接性を損う結果とな
る。
上記のような本発明法でレールを製造するが、
レールに熱間圧延終了後直ちに加速冷却処理を施
した時に耐損傷性など品質特性に特にすぐれたも
のが得られる。
（実施例及び発明の効果）
次に本発明の一実施例について説明する。
第１図は表−１に示す組成のCr−Ｖ合金鋼レ
ールのフラツシユ・バツト溶接継手部断面硬度分
布である。
(Field of Industrial Application) The present invention relates to a method for manufacturing a high-strength rail that provides quality characteristics such as wear resistance, damage resistance, and required weldability. (Conventional technology) In recent years, mining railways overseas have become heavier loaded.
In addition, the aim is to increase the speed of passenger railways. In this trend, in addition to the conventional wear resistance and damage resistance, good weldability is considered to be an important quality characteristic of rails as long rails are developed to streamline track maintenance. In response to such requirements for quality characteristics, high-strength rails with a strength of 110 to 120 grade have been developed. JP-A No. 55-125231 describes “C: 0.55-0.80%, Si: 0.5-1.20%, Mn: 0.8-0.
15%, Al: 0.005-0.05% or even Cr:
"Weldable low alloy heat treated rail containing 0.20~0.90%, Nb: 0.004~0.010%", JP-A-57-198216, "C: 0.60~0.85%, Si: 0.1~0.8%,
There are "high-strength rails with Mn: 0.70 to 1.5%, Cr: 0.2 to 0.8%, or additionally selective addition of small amounts of Nb, V, and Ti." Also, flash butt welding,
Various equipment and construction methods have been developed for rail welding, such as gas pressure welding, but in particular, if the ends of the rails to be joined are brought into light contact and the contact points are heated intensively through a large current during this time, they will overheat and melt, producing sparks. However, the flash butt welding method, in which the temperature is raised to a predetermined temperature and then pressure is rapidly applied to weld, is generally used because of the advantage that the heat-affected zone is narrow. (Problem to be solved by the invention) However, as shown in the previous example, the Cr content of 0.8% or more contained in the rail makes the pearlite structure finer and increases the strength during cooling from the high temperature during rail manufacturing. Although it is not intended to be planned, rails containing such a large amount of Cr have high hardenability at welded joints, as shown in the experimental results of the present inventors in Figure 1. It produces a martensitic structure that causes embrittlement and exhibits abnormal hardness.
There was a problem in that the wear resistance and damage resistance of the joint were significantly reduced. To prevent this problem,
Welding requires preheating or post-heat treatment, which poses a problem in welding work, which significantly impedes welding efficiency. In addition, such alloy steel rails containing Cr, Mo, etc. can be manufactured as rolled, so they have the advantage of high production efficiency. Furthermore, for heat-treated rails containing 0.2 to 0.8% Cr, the hardness of the flash and butt weld joints is reduced to H B
It is added to match the hardness of the base material, which has a hardness of 341 to 388. By forming an integral hardness of the high-strength base material and the high-strength joint, it usually achieves high wear resistance and damage resistance such as wave wear. This is achieved by using the following welding conditions (Japanese Unexamined Patent Publication No. 55-125231). The present invention utilizes the production efficiency of low-alloy steel rails, which can be manufactured as rolled or by simple heat treatment, to provide a method for manufacturing rails with high strength and excellent weld joint performance that require wear resistance and damage resistance. It is intended for this purpose. The major difference from the conventional heat-treated rail of this type described above is the production of a high-strength rail with weldability that places emphasis on damage resistance in the installation area where the rail wear environment is not so severe. In other words, it is a heat-treated rail that is intended to be used in gentle curve sections rather than the sharp curve sections where conventional high-strength heat-treated rails are laid, and for example, the head surface hardness of conventional heat-treated rails is H B 341 ~
388, whereas the rail of the present invention has an area of H B
This corresponds to the 300-340 range. (Means for solving the problems) The present invention advantageously solves the above problems, and the gist thereof is as follows: C: 0.55 to 0.85%, Si:
0.20~1.20%, Mn: 0.5~1.65%, Cr: 0.1~0.19
Or further Nb: 0.01~0.05%, V: 0.05~
0.20%, Ti: 0.01 to 0.05%, and the rest is iron and unavoidable impurities.The austenite region is heated after hot rolling or for the purpose of heat treatment. In cooling from temperature, cooling rate 1 to 800 to 450℃
This is a method for manufacturing high-strength rails that provide weldability by cooling at a rate of 4°C/sec. (Structure of the Invention) The present invention will be described in detail below. In the present invention, first, the reasons for limiting the composition of the rail as described above will be explained. C is an essential element for increasing strength and forming a pearlite structure, and is also an element that has a unique effect on wear resistance. However, if it is less than 0.55%, carbon may form at the austenite grain boundaries, which is unfavorable for wear resistance. A large amount of precipitated ferrite is generated, and if it exceeds 0.85%, not only will pro-eutectoid cementite, which is harmful to the austenite grain boundaries, be generated, but also martensite will be generated in micro-segregation areas of heat-treated layers and welds, causing embrittlement.
Limited to 0.85%. Si is an element that increases strength and improves wear resistance by solidly dissolving in ferrite in pearlite structure, but it also needs to be added at 0.20% or more as a deoxidizing element.
If it exceeds 0.20% to 1.20%, it will cause embrittlement and reduce weld bondability. Like C, Mn is an element that contributes to high strength by lowering the pearlite transformation temperature and increasing hardenability. but,
If it is less than 0.50%, its contribution is small, and if it exceeds 1.50%, martensite tends to be generated in the segregated areas, so it was limited to 0.50 to 1.50%. Cr not only contributes to high strength by lowering the pearlite transformation start temperature, but also contributes to wear resistance by strengthening the cementite in pearlite. It is an indispensable element. Conventionally, it has been thought that adding less than 0.2% of Cr is ineffective in preventing softening of the weld zone, but adding 0.1% to 0.19% of Cr is sufficiently effective, as shown in Figure 2. The hardness of the welded joint matches the hardness of the base metal. Also 0.19
% or more of Cr increases the hardness of the base metal part obtained within the cooling rate range of the steel of the present invention, resulting in a loss of integral hardness with the welded joint part. Furthermore, in the present invention, high strength and ductility can be ensured by adding austenite grain refining elements such as Nb, V, and Ti in addition to the above-mentioned components, if necessary. When Nb is heated at a low temperature during hot rolling, Nb (C, N) precipitates suppress austenite grain growth and contribute to grain refinement. Further, the austenite grains after hot rolling are made fine by high temperature heating and low temperature finish rolling, and the pearlite block size obtained after forced cooling is made fine. At this time, the effective amount of Nb added is 0.01%, and 0.05
If it exceeds %, NbC will be generated, which will even lead to embrittlement. Therefore, the Nb component range was limited to 0.01 to 0.05%. V shows almost the same tendency as Nb, but since V(C,N) that precipitates during heating has a lower melting temperature than Nb(C,N), the fineness of initial austenite grains is reduced only during low temperature heating during rail rolling. Contributes to granulation. Further, V(C,N) melted by normal heating is reprecipitated during cooling, resulting in an increase in strength due to precipitation hardening.
However, if less than 0.05% of V is added, the number of precipitates is too small and the desired effect cannot be expected. Also 0.20%
Addition of too much V causes embrittlement due to coarsening of V(C,N). For this reason, the component range of V was limited to 0.05 to 0.20%. Ti is precipitated Ti (C,
It is known that N) does not melt even at high temperatures,
Even the normal rail rolling heating temperature is effective for refining the initial grain size of austenite. but
Like Nb, the effect of Ti is small below 0.01%.
If it exceeds 0.05%, it is likely that TiN will become coarse and become the starting point of damage, so the range of Ti content should be adjusted.
Limited to 0.01-0.05%. In addition, P and S, which are unavoidable impurity components in the present invention, are harmful components that obstruct the purpose of the present invention, and must be reduced as much as possible. The rail composed of the above composition is
Molten steel is produced in a melting furnace such as a converter or electric furnace, and then subjected to ingot making, blooming or continuous casting, and then hot rolling. The hot-rolled rail is cooled from the austenite region temperature after rolling or once cooled to a low temperature and then reheated for the purpose of heat treatment. The cooling start temperature in this case is set to the austenite region temperature at a temperature at which a uniform and fine pearlite structure is generated and a wear-resistant and damage-resistant rail is obtained. In addition, for cooling, conventional high-strength heat-treated rails are used with H B 341~
The hardness range of H B 300 to 340 is targeted for the hardness range of H B 388, which naturally results in low accelerated cooling, and the cooling control temperature range is 800 to 450°C, preferably 500°C. Note that the cooling rate during this period from the austenite region temperature to the cooling control start temperature may be any rate. Such a cooling control temperature range includes all stages from the start to the end of pearlite transformation from large cross-section rails to small cross-section rails, and the cooling rate during this period is 1 to 4° C./sec. This cooling rate is
The objective is to have a somewhat lower hardness than conventional high-strength rails, and the desired hardness of H B 300 or higher cannot be achieved at a slow cooling rate of 1° C./sec or less. On the other hand, at a high speed exceeding 4° C./sec, the base metal exhibits high hardness and becomes discontinuous with the welded joint determined by the chemical composition, resulting in impaired weldability. Although rails are manufactured using the method of the present invention as described above,
When the rail is subjected to an accelerated cooling treatment immediately after hot rolling, a rail with particularly excellent quality characteristics such as damage resistance can be obtained. (Example and effects of the invention) Next, an example of the present invention will be described. Figure 1 shows the cross-sectional hardness distribution of the flash butt weld joint of the Cr-V alloy steel rail having the composition shown in Table 1.
【表】
このように高Cr含有レールでは継手部にマル
テンサイト組織が生成し異常高硬度を示す。
第２図は表−２に示す組成の従来タイプの熱処
理レールと本発明レールのフラツシユ・バツト溶
接継手部断面硬度分布を示す。[Table] As shown above, in rails with high Cr content, a martensitic structure forms in the joints and exhibits abnormally high hardness. FIG. 2 shows the cross-sectional hardness distribution of the flash butt weld joint of the conventional heat-treated rail having the composition shown in Table 2 and the rail of the present invention.
【表】
SiとCrが増量された比較鋼Ａは、溶接性を付
与した現有高強度熱処理レールは、高価なため急
曲線区間に限定使用されている。比較鋼Ｂは今や
普及型高硬度熱処理レールであるが、Crなどの
合金が添加されていないため、溶接継手部の硬度
が低下してしまい、母材部との硬度不連続性をも
たらし、しばしば列車通過時の騒音、振動の原因
となるばかりか衝撃的な負荷によるレール折損や
波状摩耗などを生成させる。また比較鋼Ａおよび
Ｂなどの高強度レールは、一方では耐摩耗性がす
ぐれているばかりに最大せん断応力の作用する位
置が固定してしまいレール内部からの折損や、疲
労ダメージの頭表面への蓄積によりハク離性の損
傷が近年クローズ・アツプして来ている。
このような本発明鋼ＣおよびＤは上記のような
観点から母材部の硬度をある程度抑制し、溶接継
手部の硬度を高めるべく微量合金添加した溶接性
付与高強度レールである。この母材部と溶接部の
一体硬度化によつて、列車の燃費向上に注目され
ているレールの塗油に対しても、連続的な一定の
レール摩耗を導き耐損傷性のすぐれた新しいタイ
プのレールが製造できる優れた効果を示すもので
ある。
表−３に本発明鋼と比較鋼の母材部の冷却速度
と冷却方法を示す。[Table] Comparative steel A with increased Si and Cr content is used only in sharply curved sections because the existing high-strength heat-treated rails with weldability are expensive. Comparative steel B is now a popular high-hardness heat-treated rail, but because it does not contain alloys such as Cr, the hardness of the welded joint decreases, resulting in hardness discontinuity with the base metal, and often Not only does it cause noise and vibration when a train passes by, but it also causes rail breakage and corrugated wear due to the impact load. In addition, high-strength rails such as comparative steels A and B have excellent wear resistance, but the position where the maximum shear stress acts is fixed, resulting in breakage from inside the rail and fatigue damage to the head surface. Due to accumulation, releasable damage has been increasing in recent years. From the above-mentioned viewpoints, the steels C and D of the present invention are high-strength rails with weldability, in which the hardness of the base metal is suppressed to some extent and a trace amount of alloy is added to increase the hardness of the welded joint. This integrated hardness of the base metal and the welded part is a new type with excellent damage resistance that leads to continuous and constant rail wear, even for rail oiling, which is attracting attention for improving train fuel efficiency. This shows the excellent effects that can be achieved by manufacturing rails. Table 3 shows the cooling rate and cooling method of the base metal of the inventive steel and comparative steel.
第１図は圧延まま合金鋼レールのフラツシユ・
バツト溶接継手部断面硬度分布を示す図、第２図
は比較鋼Ａ，Ｂと本発明鋼Ｃ，Ｄのフラツシユ・
バツト溶接継手部の断面硬度分布を示す図であ
る。
Figure 1 shows the flashing of as-rolled alloy steel rails.
Figure 2 shows the cross-sectional hardness distribution of butt welded joints.
FIG. 3 is a diagram showing the cross-sectional hardness distribution of a butt weld joint.
Claims (1)
の頭部を熱間圧延終了後あるいは熱処理する目的
で加熱されたオーステナイト域温度からの冷却に
おいて、800〜450℃間を冷却速度１〜４℃／sec
で冷却することを特徴とする溶接性を付与した高
強度レールの製造法。 ２ 重量％で Ｃ：0.55〜0.85％ Si：0.20〜1.20％ Mn：0.5 〜1.65％ Cr：0.1 〜0.19％ の他に Nb：0.01〜0.05％ Ｖ：0.05〜0.20％ Ti：0.01〜0.05％ の１種または２種以上を含有し、 残部が鉄および不可避不純物からなるレールの
頭部を、熱間圧延終了後あるいは熱処理する目的
で加熱されたオーステナイト域温度からの冷却に
おいて、800℃〜450℃間を冷却速度１〜４℃／
secで冷却することを特徴とする溶接性を付与し
た高強度レールの製造法。[Claims] 1% by weight: C: 0.55 to 0.85% Si: 0.20 to 1.20% Mn: 0.5 to 1.65% Cr: 0.1 to 0.19%, the balance being iron and inevitable impurities The head of the rail is heated. When cooling from the austenite region temperature heated for the purpose of heat treatment or after finishing rolling, the cooling rate is 1 to 4 degrees C/sec between 800 and 450 degrees Celsius.
A method for manufacturing high-strength rails with weldability, characterized by cooling. 2% by weight: C: 0.55-0.85% Si: 0.20-1.20% Mn: 0.5-1.65% Cr: 0.1-0.19%, Nb: 0.01-0.05% V: 0.05-0.20% Ti: 0.01-0.05% The head of a rail containing one or more of these, with the remainder consisting of iron and unavoidable impurities, is heated to 800°C to 450°C after hot rolling or during cooling from the austenite region temperature heated for the purpose of heat treatment. Cooling rate 1~4℃/
A method for manufacturing high-strength rails with weldability characterized by cooling at sec.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP19698085A JPS6256524A (en) | 1985-09-06 | 1985-09-06 | Manufacture of high strength rail providing weldability |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP19698085A JPS6256524A (en) | 1985-09-06 | 1985-09-06 | Manufacture of high strength rail providing weldability |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS6256524A JPS6256524A (en) | 1987-03-12 |
| JPH0138853B2 true JPH0138853B2 (en) | 1989-08-16 |
Family
ID=16366834
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP19698085A Granted JPS6256524A (en) | 1985-09-06 | 1985-09-06 | Manufacture of high strength rail providing weldability |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS6256524A (en) |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS62127453A (en) * | 1985-11-26 | 1987-06-09 | Nippon Kokan Kk <Nkk> | High-efficiency rail excellent in toughness and ductility and its production |
| JPS6362846A (en) * | 1986-09-03 | 1988-03-19 | Nippon Kokan Kk <Nkk> | High-strength low-alloy rail excellent in softening resistance in weld zone |
| BR9506522A (en) | 1994-11-15 | 1997-09-02 | Nippon Steel Corp | Perlitic steel rail that has excellent wear resistance and production method |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS57198216A (en) * | 1981-05-27 | 1982-12-04 | Nippon Kokan Kk <Nkk> | Manufacture of high-strength rail |
| JPS57207117A (en) * | 1981-06-17 | 1982-12-18 | Nippon Kokan Kk <Nkk> | Joining method for heat treated rail |
-
1985
- 1985-09-06 JP JP19698085A patent/JPS6256524A/en active Granted
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS57198216A (en) * | 1981-05-27 | 1982-12-04 | Nippon Kokan Kk <Nkk> | Manufacture of high-strength rail |
| JPS57207117A (en) * | 1981-06-17 | 1982-12-18 | Nippon Kokan Kk <Nkk> | Joining method for heat treated rail |
Also Published As
| Publication number | Publication date |
|---|---|
| JPS6256524A (en) | 1987-03-12 |
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