JPS6323244B2 - - Google Patents
Info
- Publication number
- JPS6323244B2 JPS6323244B2 JP56079400A JP7940081A JPS6323244B2 JP S6323244 B2 JPS6323244 B2 JP S6323244B2 JP 56079400 A JP56079400 A JP 56079400A JP 7940081 A JP7940081 A JP 7940081A JP S6323244 B2 JPS6323244 B2 JP S6323244B2
- Authority
- JP
- Japan
- Prior art keywords
- rail
- cooling
- strength
- cooling rate
- rails
- 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 56
- 238000004519 manufacturing process Methods 0.000 claims description 15
- 229910052750 molybdenum Inorganic materials 0.000 claims description 5
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims description 4
- 229910052804 chromium Inorganic materials 0.000 claims description 4
- 229910052710 silicon Inorganic materials 0.000 claims description 4
- 229910052802 copper Inorganic materials 0.000 claims description 3
- 229910052748 manganese Inorganic materials 0.000 claims description 3
- 229910052759 nickel Inorganic materials 0.000 claims description 3
- 239000012535 impurity Substances 0.000 claims description 2
- 229910052742 iron Inorganic materials 0.000 claims description 2
- 238000003466 welding Methods 0.000 description 19
- 238000000034 method Methods 0.000 description 14
- 239000000463 material Substances 0.000 description 11
- 238000010791 quenching Methods 0.000 description 11
- 238000005096 rolling process Methods 0.000 description 11
- 229910000831 Steel Inorganic materials 0.000 description 7
- 229910000734 martensite Inorganic materials 0.000 description 7
- 229910001562 pearlite Inorganic materials 0.000 description 7
- 239000010959 steel Substances 0.000 description 7
- 238000005275 alloying Methods 0.000 description 6
- 238000010438 heat treatment Methods 0.000 description 6
- 239000000203 mixture Substances 0.000 description 6
- 230000000171 quenching effect Effects 0.000 description 6
- 229910000851 Alloy steel Inorganic materials 0.000 description 5
- 229910000975 Carbon steel Inorganic materials 0.000 description 5
- 239000010962 carbon steel Substances 0.000 description 5
- 238000005098 hot rolling Methods 0.000 description 5
- 230000000694 effects Effects 0.000 description 4
- 230000009466 transformation Effects 0.000 description 4
- 238000009826 distribution Methods 0.000 description 3
- 238000012423 maintenance Methods 0.000 description 3
- 230000008569 process Effects 0.000 description 3
- 239000000126 substance Substances 0.000 description 3
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 3
- 230000000052 comparative effect Effects 0.000 description 2
- 238000003303 reheating Methods 0.000 description 2
- 239000007921 spray Substances 0.000 description 2
- 239000002436 steel type Substances 0.000 description 2
- 238000012360 testing method Methods 0.000 description 2
- 229910000967 As alloy Inorganic materials 0.000 description 1
- 229910019582 Cr V Inorganic materials 0.000 description 1
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 1
- 239000003570 air Substances 0.000 description 1
- 229910052799 carbon Inorganic materials 0.000 description 1
- 229910001567 cementite Inorganic materials 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 238000005336 cracking Methods 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000006356 dehydrogenation reaction Methods 0.000 description 1
- 230000001419 dependent effect Effects 0.000 description 1
- 230000006866 deterioration Effects 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 239000007789 gas Substances 0.000 description 1
- 229910052739 hydrogen Inorganic materials 0.000 description 1
- 239000001257 hydrogen Substances 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- KSOKAHYVTMZFBJ-UHFFFAOYSA-N iron;methane Chemical compound C.[Fe].[Fe].[Fe] KSOKAHYVTMZFBJ-UHFFFAOYSA-N 0.000 description 1
- 230000009916 joint effect Effects 0.000 description 1
- 238000000691 measurement method Methods 0.000 description 1
- 238000011160 research Methods 0.000 description 1
- 230000000452 restraining effect Effects 0.000 description 1
- 238000005204 segregation Methods 0.000 description 1
- 238000010008 shearing Methods 0.000 description 1
- 238000004904 shortening Methods 0.000 description 1
- 239000002002 slurry Substances 0.000 description 1
- 238000005507 spraying Methods 0.000 description 1
- 238000005496 tempering Methods 0.000 description 1
- 239000003832 thermite Substances 0.000 description 1
- 229910052720 vanadium Inorganic materials 0.000 description 1
- 239000002023 wood Substances 0.000 description 1
- 229910000859 α-Fe Inorganic materials 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D9/00—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
- C21D9/04—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for rails
Landscapes
- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Physics & Mathematics (AREA)
- Thermal Sciences (AREA)
- Crystallography & Structural Chemistry (AREA)
- Mechanical Engineering (AREA)
- Materials Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Heat Treatment Of Articles (AREA)
- Heat Treatment Of Steel (AREA)
Description
本発明はレールの製造方法特に高軸重下におけ
る摩耗および高速運転時におけるシエリング疵な
ど疲労損傷の発生が少なくかつ溶接性の良好な
130Kg／mm2以上の高強度レールの製造方法に関す
るものである。
近年における鉄道輸送は高軸重下、高速化を指
向しつつあり、そのためレールの使用条件は苛酷
になる傾向にある。この結果レール頭部の摩耗や
疲労が激しく、レール寿命の短縮によりメンテナ
ンスに支障を来たすことから、レール頭部の高強
度化が要求されており、また一方では、レール継
目部の破損防止、乗り心地並びに騒音などの対策
からレールの溶接によるロングレール化も進めら
れ、レールの溶接性も不可欠な条件となつてい
る。
一般にレール全体もしくはレール頭部の高強度
化を図つたレールとして、従来次のようなものが
知られている。
イ 多量の合金元素を添加して通常の熱間圧延後
放冷して製造したレール（以下単に合金鋼レー
ルと称す）。
ロ 炭素鋼レールを熱間圧延後再加熱して熱処理
を施したレール（以下単にスラツククエンチレ
ールと称す）。
しかして、イの合金鋼レールは、通常の炭素鋼
レール成分にSi、Cr、Mo、Ｖなどの合金元素を
多量添加した鋼を熱間圧延し、その後自然放冷し
て110Kg／cm2以上の引張り強さを与えたものであ
る。このレールは圧延ままで製造されるため生産
能率は優れている。しかし、圧延後の冷却が自然
放冷であるため冷却速度が850℃〜500℃間におい
て0.3〜0.8℃／secと小さく、この冷却条件で高強
度を得るには、パーライト変態の鼻位置を連続冷
却変態図（C.C.T）の長時間側（焼入性を向上さ
せる側）に移行させる必要があり、多量の合金元
素を添加せざるを得ない。そのためコスト高とな
り、また同じく水素割れ感受性が増大するため脱
水素処理などの工程が必要となり、これまた生産
コストを押し上げることから必ずしも経済的に有
利な方法ではない。
更に品質面においては、このレールをロングレ
ール化するために溶接した場合、溶接継手部およ
び溶接熱影響部における溶接後の冷却速度が850
℃〜500℃間で１〜４℃／secと圧延後のそれに比
べ大きいため、鋼種によつてはレール継手部の一
部又は全体にマルテンサイト組織を生成させ、第
１図に示すように母材レールに比し著しく硬化す
る。そのため、溶接継手部におけるレールの折損
や不均一な摩耗現象を呈し、メンテナンス面で大
きな問題となる。そこで、このマルテンサイト発
生による硬化を敬減するため溶接後恒温処理や焼
戻処理の後熱処理が実施されるが、溶接能率の著
しい低下を来すことを避けられない。
次にロのスラツククエンチレールは、アメリカ
鉄道規格（以下AREAと称す）にもあるように、
熱間圧延後放冷した炭素鋼レールを火炎又は高周
波によりAc3変態点以上に再加熱した後、圧縮空
気又は噴霧若しくは水により850℃〜500℃間を５
〜15℃／secの冷却速度で加速冷却して低温域に
てパーライト変態を生ぜしめ、その組織を緻密な
パーライトとしたレールである。
このレールは、合金鋼レールと異なり合金元素
の添加が不要であるため、合金元素添加コスト面
では安価である。しかし、圧延後の再加熱処理に
必要なエネルギーが新たに入要になること、更に
連続炉の場合に加熱能率はたかだか700〜800mm／
min程度であつて生産能率の大幅な低下を来たす
ため、必ずしも総合的に経済的な製造法とはいえ
ない。
また品質面でも、このレールを溶接した場合、
溶接時に一旦オーステナイト化されると、もとも
と前記冷却速度によるスラツククエンチ処理によ
り高強度を有していたものが、溶接後の冷却速度
が前述の如くスラツククエンチ時の冷却速度に比
し小さいことや、その組成が炭素鋼であつて合金
元素を多量に含有しないことなどにより第１図に
示すように溶接継手部に軟化を生じる。その結
果、溶接継手部軟化部分で不均一摩耗や塑性変形
を呈し、メンテナンスが難しくなる。
本発明は前記したように製造上および品質上で
一長一短のあつた従来の高強度レール製造方法の
欠点を解消するために研究を重ねて創案されたも
ので、その基本的な目的は経済的に安価で、生産
能率が高くかつ溶接継手性能にすぐれた130Kg／
mm2以上の高強度レールの製造方法を提供すること
にある。
上記目的を達成するため本発明は溶接後の冷却
速度に見合う冷却速度でレール圧延ライン上でス
ラツククエンチ処理を実施し、かつ前記冷却速度
においても130Kg／mm2以上の引張り強さを与える
ようにレール組成をして焼入性を高めた組成とす
るものである。
すなわち、本発明は、Ｃ；0.60〜0.85％、Si；
0.1〜0.8％、Mn；0.7〜1.5％、Cr；0.2〜0.8％を
含有し、これにMo；0.03〜0.10％、Cu；0.05〜
0.5％、Ni；0.1〜0.5％の一種又は二種以上を添加
し、残部鉄及び不可避的不純物を有するレールを
熱間圧延し、次いでレール頭部又はレール全体を
850℃〜500℃間の冷却速度を１〜４℃／secで加
速冷却することを特徴とするものである。
このような本発明によるときには、溶接継手性
能のすぐれた微細なパーライト組織を有する高強
度レール（レール頭部引張強さ130Kg／mm2以上）
が容易に得られる。従来から知られているように
微細パーライト組織を呈しその引張り強さが120
Kg／mm2以上のものはほとんど摩耗らしい摩耗を生
じない。また製造上も圧延後の顕熱を有効に利用
できるため生産能率を向上できる。
以下本発明について詳細に説明する。
本発明は高強度レールを製造するにあたりまず
下記に示す特定の化学組成のレール用鋼を用い
る。
Ｃ；0.60〜0.85％、Si；0.1〜0.8％、Mn；0.7〜
1.5％、Cr；0.2〜0.8％、更にMo；0.03〜0.10％、
Cu；0.05〜0.5％、Ni；0.1〜0.5％の一種又は二種
以上を含有する前記化学成分について限定した理
由を述べると、まず「Ｃ」については共析鋼とし
ての強度確保のため0.60％以上必要であるが、
0.85％以上超えると粒界に初析セメンタイトを生
成させ、材質の脆性を引き起すので好ましくな
い。従つて「Ｃ」の成分範囲0.60〜0.85％とし
た。
「Si」については脱酸元素として0.1％以上添
加することが必要であり、かつ「Si」量の増加は
フエライト地を強化させ強度を向上をもたらす。
然し0.8％を超えると強度上昇の割合が小さく且
つ溶接継手特性も低下させるので「Si」量を0.1
〜0.8％に限定した。
「Mn」については「Si」と同様脱酸元素とし
て不可欠な元素であり且つ焼入性を上げるため
0.7％以上を必要とするが、1.5％を超えると鋼の
ミクロ偏析によるマルテンサイト組織を生じやす
く、熱処理時および溶接時に硬化や脆化を生じ、
材質劣化を来すので好ましくない。従つて
「Mn」量を0.7〜1.5％に限定した。
「Cr」については本発明において最も重要な
元素である。「Cr」は0.2％以上添加するとパーラ
イトのラメラー間隔を狭くし高強度が得られる。
第２図にCr量による強度変化を示すが、Cr量の
増加と共に顕著な硬度上昇が認められる。しか
し、0.8％を超えると、３℃／sec以上の冷却速度
ではマルテンサイト組織を混入させる嫌いがあり
好ましくない。従つて「Cr」の成分範囲を0.2〜
0.8％に限定した。
更に、本発明の目的とする130Kg／mm2以上の高
強度レールを製造する場合、安定して強度を向上
できる元素の添加が重要である。それらの元素と
して「Mo」，「Cu」，「Ni」がある。
「Mo」については焼入性を高めるため高強度
が得られる。しかし、添加量が0.03％以下ではそ
の効果が小さく、0.1％以上では焼入性が上がり
すぎ、冷却速度が３℃／sec以上ではマルテンサ
イト組織を生成させる傾向にある。従つて
「Mo」量を0.03〜0.10％に限定した。
「Cu」および「Ni」はともに加熱および冷却
条件による強度上昇の依存性が小さく、安定して
強度を向上させる点で有利である。Cuの場合、
0.05％以下ではその効果が小さく、0.5％を超え
ると強度上昇の割には経済性面から不利である。
従つて0.05〜0.5％に限定した。又Niの場合、0.1
％以下ではその効果が小さく、0.5％を超えると
同じく経済性の面で不利であるので0.1％〜0.5％
に限定した。
次に、本発明は上記の成分組成を有するレール
用鋼を熱間圧延後オーステナイト域から850℃〜
500℃間の冷却速度を１〜４℃／secで加速冷却す
る。この加速冷却すなわちスラツククエンチ処理
を詳述すると、まず本発明において冷却速度を
850℃〜500℃間で１〜４℃／secとしたのは、溶
接時の冷却速度に合わせることにより溶接継手部
の硬化部および軟化部の発生を防止するためであ
る。現状のレール溶接方法としてはフラツシユバ
ツト溶接、ガス圧接、エンクローズドアーク溶接
およびテルミツト溶接が主として採用されている
が、これらの各種溶接法における溶接部の850℃
〜500℃間の冷却速度は１〜４℃／sec間にある。
従つてこの冷却速度以外の冷却速度をもつて加速
冷却すると、前記のように溶接部の軟化部が生じ
たり、マルテンサイト組織が生じたりして本発明
の目的は達成されない。また仮りに溶接部の冷却
速度として１℃／sec未満又は４℃／secを超える
溶接方法が存在し又は開発されたとしても、前者
の溶接方法に対しては既に説明した合金鋼レール
が、また後者の溶接法に対してはこれまた既述の
現状の炭素鋼レールをスラツククエンチしたもの
が適しており特に本発明によるレールを用いる必
要はない。
なお、化学成分と冷却速度との関係は密接であ
るため、厳密には冷却速度の最適範囲が存在す
る。即ち、基本成分（Si−Mn−Cr）では、第３
図に示すように冷却速度２〜３℃／sec間で微細
パーライト組成を有する高強度レールが得られ、
冷却速度３〜４℃／sec間ではマルテンサイト組
織や中間組織を混入させる恐れがあるため、冷速
のコントロールに注意を要する。むしろ低冷速側
の１〜２℃／secについては「基本成分＋Mo」系
で、１〜３℃／secについては「基本成分＋Cu＋
Ni」系でそれぞれ130Kg／mm2以上を有する高強度
レールが得られる。
しかして、スラツククエンチに関しては既述の
ように850℃〜500℃間の温度範囲で１〜４℃／
secの冷却速度が必要であるが、この加速冷却は
熱間仕上圧延後直ちにレール圧延ライン上で実施
するものである。その冷却方法は圧縮空気冷却、
蒸気冷却、噴霧冷却、水冷および流動層冷却のい
ずれでも可能であり、いずれにしても圧延ライン
上での冷却であるため圧延の顕熱を有効に利用す
ることができ、更に圧延速度と熱処理速度とを一
致させることにより従来のライン外での再加熱ス
ラツククエンチ法より大幅な生産能率の向上を期
待できる。
なお、上記の冷却中にレールの曲がりが発生す
る場合、この曲がりを拘束ローラで拘束しつつ冷
却し又は局部的熱処理により矯正してもよい。
次に本発明の実施例を示すと以下のとおりであ
る。
実施例
本発明により高強度レールを製造した。第１表
に供試鋼の組成およびスラツククエンチ時の850
℃〜500℃間の冷却速度（試番２及び３）並びに
熱間圧延後の850℃〜500℃間の冷却速度（試番８
〜９）を、第２表にはかくして得られたレールの
機械的性質を示す。
なお、第１表、第２表において、試番２及び３
は本発明材であり、該試番２，３は「基本成分＋
Mo，Cu＋Ni」系である。試番７〜９は比較材で
あり、試番７は現状のスラツククエンチレール、
試番８はCr−Ｖ合金鋼レール、試番９はCr−Mo
合金鋼である。本発明材はすべて60Kgレールに
950℃で仕上圧延し、直ちに噴霧又は水により冷
却を開始し、850℃〜500℃間を所要の最適冷却速
度で冷却した。試番３は約2.5℃／sec、試番２は
約1.5℃／secである。
The present invention is a method for manufacturing rails, which is characterized by less wear under high axle loads and less fatigue damage such as shearing defects during high-speed operation, and which has good weldability.
This invention relates to a method for manufacturing high-strength rails of 130Kg/mm 2 or more. In recent years, rail transportation has been moving toward higher speeds with higher axle loads, and the conditions for using rails have therefore tended to become harsher. As a result, the rail head is subject to severe wear and fatigue, shortening the rail life and complicating maintenance.Therefore, there is a need for higher strength rail heads. Longer rails are being made by welding the rails in order to improve comfort and reduce noise, and the weldability of the rails has also become an essential condition. In general, the following rails are known as rails that are designed to increase the strength of the entire rail or the rail head. (a) Rails manufactured by adding a large amount of alloying elements and cooling after normal hot rolling (hereinafter simply referred to as alloy steel rails). (b) Rails made of carbon steel rails that have been hot-rolled and then reheated and heat-treated (hereinafter simply referred to as slack quench rails). Therefore, the alloy steel rail of A is made by hot rolling steel in which a large amount of alloying elements such as Si, Cr, Mo, and V are added to the ordinary carbon steel rail components, and then letting it cool naturally to produce 110 kg/cm 2 or more. It gives a tensile strength of . Since this rail is manufactured as rolled, production efficiency is excellent. However, since cooling after rolling is natural cooling, the cooling rate is as low as 0.3 to 0.8°C/sec between 850°C and 500°C, and in order to obtain high strength under this cooling condition, the nose position of pearlite transformation must be continuously It is necessary to shift to the long time side of the cooling transformation diagram (CCT) (the side that improves hardenability), and a large amount of alloying elements must be added. This increases the cost and also increases the susceptibility to hydrogen cracking, necessitating a process such as dehydrogenation treatment, which also increases production costs and is therefore not necessarily an economically advantageous method. Furthermore, in terms of quality, when this rail is welded to make a long rail, the cooling rate after welding in the weld joint and weld heat affected zone is 850%.
℃ to 500℃, which is 1 to 4℃/sec, which is larger than that after rolling, so depending on the steel type, a martensitic structure is generated in part or the whole of the rail joint, as shown in Figure 1. It is noticeably harder than wood rails. As a result, rail breakage and uneven wear occur at welded joints, which poses a major problem in terms of maintenance. Therefore, in order to reduce the hardening caused by the generation of martensite, constant temperature treatment after welding or heat treatment after tempering treatment is carried out, but a significant decrease in welding efficiency cannot be avoided. Next, the slack quench rail in Russia is as stated in the American Railway Standards (hereinafter referred to as AREA).
Carbon steel rails that have been left to cool after hot rolling are reheated to Ac 3 transformation point or higher using flame or high frequency, and then heated between 850°C and 500°C for 50°C using compressed air, spray, or water.
It is a rail that undergoes accelerated cooling at a cooling rate of ~15°C/sec to cause pearlite transformation in the low temperature range, resulting in a dense pearlite structure. Unlike alloy steel rails, this rail does not require the addition of alloying elements, so it is inexpensive in terms of the cost of adding alloying elements. However, additional energy is required for reheating treatment after rolling, and in the case of a continuous furnace, the heating efficiency is only 700 to 800 mm/mm.
This method is not necessarily an economical manufacturing method as a whole, as it causes a significant drop in production efficiency. Also, in terms of quality, when this rail is welded,
Once austenitized during welding, although it originally had high strength due to the slack quenching process using the cooling rate, the cooling rate after welding is smaller than the cooling rate during slack quenching as described above. Also, because the composition is carbon steel and does not contain a large amount of alloying elements, softening occurs in the welded joint as shown in FIG. As a result, the softened portion of the welded joint exhibits uneven wear and plastic deformation, making maintenance difficult. As mentioned above, the present invention was created through repeated research in order to eliminate the drawbacks of the conventional high-strength rail manufacturing method, which has both advantages and disadvantages in terms of manufacturing and quality. 130Kg/Low price, high production efficiency, and excellent welded joint performance.
The purpose of the present invention is to provide a method for manufacturing high-strength rails of mm 2 or more. In order to achieve the above object, the present invention carries out a slack quench treatment on a rail rolling line at a cooling rate commensurate with the cooling rate after welding, and also provides a tensile strength of 130 kg/mm 2 or more even at the cooling rate. The rail composition is made to improve hardenability. That is, the present invention includes C; 0.60 to 0.85%, Si;
Contains 0.1 to 0.8%, Mn; 0.7 to 1.5%, Cr; 0.2 to 0.8%, Mo; 0.03 to 0.10%, Cu; 0.05 to
0.5%, Ni; 0.1 to 0.5% of one or more kinds are added, the rail with the balance iron and unavoidable impurities is hot rolled, and then the rail head or the entire rail is rolled.
It is characterized by accelerated cooling at a cooling rate of 1 to 4°C/sec between 850°C and 500°C. According to the present invention, a high-strength rail having a fine pearlite structure with excellent weld joint performance (rail head tensile strength of 130 Kg/mm 2 or more)
can be easily obtained. As is known from the past, it exhibits a fine pearlite structure and its tensile strength is 120.
Items of Kg/mm 2 or more hardly cause wear-like wear. In addition, production efficiency can be improved since the sensible heat after rolling can be used effectively. The present invention will be explained in detail below. In manufacturing a high-strength rail, the present invention first uses rail steel having the specific chemical composition shown below. C; 0.60~0.85%, Si; 0.1~0.8%, Mn; 0.7~
1.5%, Cr; 0.2-0.8%, further Mo; 0.03-0.10%,
To explain the reason for limiting the above chemical components containing one or more of Cu; 0.05 to 0.5% and Ni; 0.1 to 0.5%, first, "C" is 0.60% to ensure strength as a eutectoid steel. Although more than that is necessary,
If it exceeds 0.85%, pro-eutectoid cementite is generated at the grain boundaries, causing brittleness of the material, which is not preferable. Therefore, the component range of "C" was set at 0.60 to 0.85%. It is necessary to add 0.1% or more of "Si" as a deoxidizing element, and an increase in the amount of "Si" strengthens the ferrite base and improves its strength.
However, if it exceeds 0.8%, the rate of increase in strength will be small and the welded joint properties will also deteriorate, so the amount of "Si" should be reduced to 0.1%.
Limited to ~0.8%. Like "Si", "Mn" is an essential element as a deoxidizing element, and it also improves hardenability.
A content of 0.7% or more is required, but if it exceeds 1.5%, martensitic structures are likely to occur due to micro-segregation of the steel, resulting in hardening and embrittlement during heat treatment and welding.
This is not preferable because it causes material deterioration. Therefore, the amount of "Mn" was limited to 0.7-1.5%. "Cr" is the most important element in the present invention. Adding 0.2% or more of Cr narrows the lamellar spacing of pearlite and provides high strength.
Figure 2 shows the change in strength depending on the amount of Cr, and it is observed that the hardness increases markedly as the amount of Cr increases. However, if it exceeds 0.8%, it is not preferable because a cooling rate of 3° C./sec or higher tends to mix martensite structure. Therefore, the component range of "Cr" should be 0.2~
Limited to 0.8%. Furthermore, when manufacturing a high-strength rail of 130 kg/mm 2 or more, which is the object of the present invention, it is important to add elements that can stably improve the strength. These elements include "Mo", "Cu", and "Ni". As for "Mo", high strength can be obtained because it improves hardenability. However, if the amount added is less than 0.03%, the effect is small, if it is more than 0.1%, the hardenability increases too much, and if the cooling rate is 3° C./sec or more, a martensitic structure tends to be generated. Therefore, the amount of "Mo" was limited to 0.03-0.10%. Both "Cu" and "Ni" are advantageous in that the increase in strength is less dependent on heating and cooling conditions and can stably improve strength. In the case of Cu,
If it is less than 0.05%, the effect will be small, and if it exceeds 0.5%, it will be disadvantageous from an economical point of view, despite the increase in strength.
Therefore, it was limited to 0.05-0.5%. Also, in the case of Ni, 0.1
If it is less than 0.5%, the effect will be small, and if it exceeds 0.5%, it will be economically disadvantageous, so 0.1% to 0.5%.
limited to. Next, the present invention produces rail steel having the above-mentioned composition from the austenitic region after hot rolling at 850°C to 850°C.
Accelerated cooling is performed at a cooling rate of 1 to 4°C/sec between 500°C and 500°C. To explain this accelerated cooling or slack quenching process in detail, firstly, in the present invention, the cooling rate is
The reason for setting the cooling rate to 1 to 4°C/sec between 850°C and 500°C is to prevent the occurrence of hardened and softened parts in the welded joint by matching the cooling rate during welding. Currently, flash butt welding, gas pressure welding, enclosed arc welding, and thermite welding are mainly used as rail welding methods.
The cooling rate between ~500°C is between 1 and 4°C/sec.
Therefore, if accelerated cooling is performed at a cooling rate other than this cooling rate, the object of the present invention will not be achieved because a softened portion or a martensitic structure will occur in the welded portion as described above. Furthermore, even if a welding method with a cooling rate of less than 1°C/sec or more than 4°C/sec exists or is developed, the alloy steel rail described above may also be used for the former welding method. For the latter welding method, the previously mentioned existing carbon steel rails obtained by slack quenching are also suitable, and there is no particular need to use the rails according to the present invention. Note that, since there is a close relationship between chemical components and cooling rate, strictly speaking, there is an optimum range of cooling rate. That is, in the basic component (Si-Mn-Cr), the third
As shown in the figure, a high-strength rail with a fine pearlite composition is obtained at a cooling rate of 2 to 3°C/sec.
If the cooling rate is between 3 and 4°C/sec, there is a risk that martensite structure or intermediate structure will be mixed in, so care must be taken to control the cooling rate. Rather, for 1 to 2℃/sec on the low cooling rate side, it is a "basic component + Mo" system, and for 1 to 3℃/sec, it is a "basic component + Cu + Mo" system.
High-strength rails of 130 Kg/mm 2 or more can be obtained using the "Ni" system. However, regarding slack quenching, as mentioned above, in the temperature range of 850℃ to 500℃, 1 to 4℃/
A cooling rate of sec is required, and this accelerated cooling is performed on the rail rolling line immediately after hot finish rolling. Its cooling method is compressed air cooling.
Steam cooling, spray cooling, water cooling, and fluidized bed cooling are all possible; in any case, since the cooling is done on the rolling line, the sensible heat of rolling can be used effectively, and the rolling speed and heat treatment speed can be reduced. By matching these, we can expect a significant improvement in production efficiency compared to the conventional off-line reheating slurry quench method. In addition, if the rail bends during the above-mentioned cooling, the bend may be corrected by cooling while being restrained by a restraining roller or by local heat treatment. Next, examples of the present invention are shown below. EXAMPLE A high-strength rail was manufactured according to the present invention. Table 1 shows the composition of the sample steel and 850 at the time of slack quenching.
The cooling rate between ℃ and 500℃ (trial numbers 2 and 3) and the cooling rate between 850℃ and 500℃ after hot rolling (trial number 8)
~9), Table 2 shows the mechanical properties of the rails thus obtained. In addition, in Tables 1 and 2, trial numbers 2 and 3
is the material of the present invention, and the trial numbers 2 and 3 are the “basic components +
Mo, Cu + Ni” system. Trial numbers 7 to 9 are comparison materials, trial number 7 is the current slack quench rail,
Trial number 8 is Cr-V alloy steel rail, trial number 9 is Cr-Mo
It is alloy steel. All invented materials are used for 60Kg rails.
Finish rolling was carried out at 950°C, and cooling was immediately started by spraying or water, and cooling was carried out between 850°C and 500°C at the required optimum cooling rate. Trial No. 3 was approximately 2.5°C/sec, and Trial No. 2 was approximately 1.5°C/sec.
【表】【table】
【表】
上記第２表から明らかなように、本発明材は比
較材より耐力、引張り強さ、伸び、表面硬さ、摩
耗量（西原式摩耗試験）の全てにおいて良好であ
る。試番２および３ではMo添加又はCu＋Ni添加
により133Kg／mm2程度の強度を呈している。
第４図に本発明材の試番３についてフラツシユ
バツト溶接を実施し溶接継手部の硬度分布を検討
した結果を示す。図中横軸の０点は溶接個所で、
その左右の頭部から５mmの位置の硬度をビツカー
ス試験で測定したものである。この測定法は第１
図の場合と同じである。上記第４図から明らかな
ように、本発明材では熱影響部における狭い硬化
部は存在するが、継手部近傍では母材と同等の硬
度を有しており、第１図の比較材の場合に比べ著
しくすぐれていることがわかる。
以上説明した本発明によるときには、頭部引張
強さが130Kg／mm2以上でかつ溶接性にすぐれた高
強度レールを製造できるというすぐれた効果が得
られる。[Table] As is clear from Table 2 above, the materials of the present invention are better than the comparative materials in all of the yield strength, tensile strength, elongation, surface hardness, and amount of wear (Nishihara type wear test). Trial numbers 2 and 3 exhibited a strength of approximately 133 Kg/mm 2 due to the addition of Mo or Cu+Ni. FIG. 4 shows the results of performing flash butt welding on trial number 3 of the material of the present invention and examining the hardness distribution of the welded joint. The zero point on the horizontal axis in the figure is the welding location,
The hardness at a position 5 mm from the left and right heads was measured using the Bitkers test. This measurement method is the first
Same as in the figure. As is clear from Figure 4 above, the material of the present invention has a narrow hardened area in the heat-affected zone, but the hardness near the joint is equivalent to that of the base material, and in the case of the comparative material shown in Figure 1. It can be seen that it is significantly superior to . According to the present invention as described above, it is possible to produce a high-strength rail having a head tensile strength of 130 Kg/mm 2 or more and excellent weldability.
第１図は従来法によるレールをフラツシユバツ
ト溶接した場合の継手部硬度分布を示すグラフ、
第２図は本発明におけるCr含有量の引張り強さ
に及ぼす影響を示すグラフ、第３図は本発明にお
ける各鋼種の冷却速度依存性（850℃〜500℃間）
を示すグラフ、第４図は本発明法によるレールを
フラツシユバツト溶接した場合の継手部硬度分布
を示すグラフである。
Figure 1 is a graph showing the hardness distribution of joints when rails are flat butt welded using the conventional method.
Figure 2 is a graph showing the effect of Cr content on tensile strength in the present invention, and Figure 3 is a graph showing the cooling rate dependence of each steel type in the present invention (between 850℃ and 500℃).
FIG. 4 is a graph showing the hardness distribution of the joint when the rail is flat butt welded by the method of the present invention.
Claims (1)
〜1.5％、Cr；0.2〜0.8％を含有し、これにMo；
0.03〜0.10％、Cu；0.05〜0.5％、Ni；0.1〜0.5％
の一種又は二種以上を添加し、残部鉄及び不可避
的不純物を有するレールを熱間圧延し、次いで
850℃〜500℃間の冷却速度を１〜４℃／secで加
速冷却することを特徴とする130Kg／mm2以上の高
強度レールの製造方法。1 C; 0.60-0.85%, Si; 0.1-0.8%, Mn; 0.7
Contains ~1.5%, Cr; 0.2-0.8%, and Mo;
0.03~0.10%, Cu; 0.05~0.5%, Ni; 0.1~0.5%
One or more of these are added, and the rail with the balance iron and unavoidable impurities is hot-rolled, and then
A method for producing a high-strength rail of 130 Kg/mm 2 or more, characterized by accelerated cooling at a cooling rate of 1 to 4° C./sec between 850° C. and 500° C.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP7940081A JPS57198216A (en) | 1981-05-27 | 1981-05-27 | Manufacture of high-strength rail |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP7940081A JPS57198216A (en) | 1981-05-27 | 1981-05-27 | Manufacture of high-strength rail |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS57198216A JPS57198216A (en) | 1982-12-04 |
| JPS6323244B2 true JPS6323244B2 (en) | 1988-05-16 |
Family
ID=13688796
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP7940081A Granted JPS57198216A (en) | 1981-05-27 | 1981-05-27 | Manufacture of high-strength rail |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS57198216A (en) |
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| JPS63147454U (en) * | 1987-03-17 | 1988-09-28 | ||
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| DE3446794C1 (en) * | 1984-12-21 | 1986-01-02 | BWG Butzbacher Weichenbau GmbH, 6308 Butzbach | Process for the heat treatment of pearlitic rail steel |
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Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5047808A (en) * | 1973-05-02 | 1975-04-28 | ||
| JPS55125231A (en) * | 1979-03-17 | 1980-09-26 | Nippon Steel Corp | Production of weldable low alloy heat treated hard top rail |
-
1981
- 1981-05-27 JP JP7940081A patent/JPS57198216A/en active Granted
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5047808A (en) * | 1973-05-02 | 1975-04-28 | ||
| JPS55125231A (en) * | 1979-03-17 | 1980-09-26 | Nippon Steel Corp | Production of weldable low alloy heat treated hard top rail |
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|---|---|---|---|---|
| JPS63147454U (en) * | 1987-03-17 | 1988-09-28 | ||
| JPH0912037A (en) * | 1995-06-29 | 1997-01-14 | Maruzen Kogyo Kk | Envelope |
| 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 |
| US9534278B2 (en) | 2012-06-14 | 2017-01-03 | Nippon Steel & Sumitomo Metal Corporation | Rail |
| US10047411B2 (en) | 2015-01-23 | 2018-08-14 | Nippon Steel & Sumitomo Metal Corporation | Rail |
| CN107475609A (en) * | 2017-08-09 | 2017-12-15 | 侯宇岷 | A kind of wear-resisting Steel Bar, wear-resisting rod iron and preparation method thereof |
| WO2020054339A1 (en) | 2018-09-10 | 2020-03-19 | 日本製鉄株式会社 | Rail, and method for manufacturing rail |
| WO2020189232A1 (en) | 2019-03-15 | 2020-09-24 | 日本製鉄株式会社 | Rail |
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|---|---|
| JPS57198216A (en) | 1982-12-04 |
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