JPS5993838A - Improvement of fracture resistance of weld zone of rail - Google Patents
Improvement of fracture resistance of weld zone of railInfo
- Publication number
- JPS5993838A JPS5993838A JP20199682A JP20199682A JPS5993838A JP S5993838 A JPS5993838 A JP S5993838A JP 20199682 A JP20199682 A JP 20199682A JP 20199682 A JP20199682 A JP 20199682A JP S5993838 A JPS5993838 A JP S5993838A
- Authority
- JP
- Japan
- Prior art keywords
- rail
- zone
- head
- weld zone
- weld
- 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.)
- Pending
Links
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
- C21D9/50—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for welded joints
Abstract
Description
【発明の詳細な説明】
本発明はレール溶接部の耐破壊特性向上に関するもので
ある。DETAILED DESCRIPTION OF THE INVENTION The present invention relates to improving the fracture resistance of rail welds.
レールの継目は列車通過による衝撃および振動などのた
め、レールおよび継目板等に損傷が発生１７やすく、保
守管理上問題があり、さらに乗心地なども悪いことなど
力）ら、最近は溶接によるロングレール化が計られてい
る。その結果、レール損１易も減少傾向にあり、捷た、
快適な乗心地が得られるようになってき１こ。しかし溶
接部には浴接時の熱影響に、Ｊ：クレール頭部硬さの不
均一（熱影響）部の発生に避は難く、敷設後の摩耗など
により凹凸が発生する。さらに溶接変形等もあり、これ
らが重畳して列車通過の際、溶接部に衝撃荷重が負荷す
る。その結果、レール溶接部に於て、頭頂面からころが
り損傷が発生し１こりあるいはレール底部からの疲労破
壊が問題となっていた。Rail joints are susceptible to shocks and vibrations caused by passing trains, which can easily cause damage to the rails and joint plates, which poses problems in maintenance and management, as well as poor riding comfort. Plans are being made to create a rail system. As a result, rail losses are on the decline, and rail losses are decreasing.
I have started to get a comfortable ride. However, it is difficult to avoid the occurrence of uneven hardness (heat affected) in the welded part due to the heat effect during bath welding, and unevenness occurs due to wear after installation. In addition, there are weld deformations, etc., and when a train passes, an impact load is applied to the welded part. As a result, rolling damage occurred from the top surface of the rail weld, causing problems such as stiffness or fatigue failure from the bottom of the rail.
その１こめ、最近に溶接部のレール頭部硬さの不均一を
改善し、さらに微細パーライト組織にして高強度化する
ｆコめに、レール頭部を溶接後再熱処理する技術が開発
され１こ。これにより、レール頭部硬さの不均一が改善
され摩耗による溶接部の凹凸か少なくなることにより列
車通過時の衝撃荷重か小さくなり、さらに高強度化して
いるために溶接部の破壊特性が改善され損傷事故もか′
ｆｒ、り減少してきた。1. Recently, a technology has been developed in which the rail head is reheated after welding in order to improve the non-uniform hardness of the rail head at the welded part and create a fine pearlite structure to increase the strength. child. This improves the unevenness of the hardness of the rail head, reduces the unevenness of the weld due to wear, reduces the impact load when trains pass, and improves the fracture characteristics of the weld due to increased strength. There may also be damage caused by an accident.
fr has been decreasing.
ところが最近［なりこれまで予期されなかった唇接部位
からの破壊が問題となっている。すなわち、その損傷例
を第１図（ｂ）に示す。損傷はレール浴接部４の腹部の
はソ中央を起点５としてき裂６が発生し、レール長手方
向および腹部板厚方向に進展し、最終的にに横裂に至る
ものである。き裂の発生は直線７曲線を問わず、捷ｆこ
レールのフィールド１則およびゲージコーナー側則とも
に見られる。However, recently, damage from the lip contact area, which had not been expected until now, has become a problem. That is, an example of the damage is shown in FIG. 1(b). The damage is caused by a crack 6 starting from the center 5 of the abdomen of the rail bath contact portion 4, propagating in the longitudinal direction of the rail and the thickness direction of the abdomen, and finally leading to a transverse crack. The occurrence of cracks can be seen in both the field 1 rule and the gauge corner side rule, regardless of the straight line 7 curves.
このような損傷の発生原因については当初、溶接欠陥と
かあるいは車輪の偏荷重により腹部に曲げ（引張）応力
が作用するためと言われていた。Initially, it was thought that the cause of such damage was due to welding defects or bending (tensile) stress acting on the abdomen due to uneven loading of the wheel.
しかし、溶接欠陥が々くても、また、圧縮のみの曲げ応
力が負荷するレールのゲージコーナー側でもき裂の発生
が認められること力Δら、真の原因は明らかにされない
ま＼、勿論対策についても何ら講じられていなかった。However, even though there are many welding defects, cracks are also observed on the gauge corner side of the rail where only compressive bending stress is applied, so the true cause remains unknown. Nothing was taken about this either.
そこで発明者らは本損傷に対し効果的対策を講する目的
で、本損傷の再現実験および原因について諸検討を行っ
た。その結果、本損傷の発生原因は第２図にその１例を
示すように、レール溶接部の腹部中央に、垂直方向の非
常に大きな引張残留応力が発生しているためであること
がわ力１つ１こ。In order to take effective measures against this damage, the inventors conducted experiments to reproduce this damage and conducted various studies on the causes. As a result, we found that the cause of this damage was the occurrence of extremely large tensile residual stress in the vertical direction at the center of the abdomen of the rail weld, as shown in Figure 2. One by one.
したがってこの引張残留応力を除去するかあるいは圧縮
に変えれば損傷の発生をかなり防止できることがわかつ
１こ。さらに、一般に溶接部の腹部あるいは底部は直接
車輪と接触しないため、その仕−Ｌげは単なるパリ取り
を行った丑＼かあるいは非常に目の粗いグラインダーで
の仕上げま＼が多い。Therefore, it can be seen that if this tensile residual stress is removed or changed to compressive stress, damage can be significantly prevented from occurring. Furthermore, since the abdomen or bottom of the weld generally does not come into direct contact with the wheel, the finish is often simply deburred or finished with a very coarse grinder.
しｆこがってこれら研削疵が応力集中となｆｌこめ疲労
限度が低くなることも考慮し、単に腹部の残留応力を制
御するのみならず、腹部を高強度化しレール自身の抵抗
力（疲労限度）を高めることにより、完全に本損傷の発
生を防止できることがわかつｆこ。Taking into account that these grinding flaws cause stress concentration, which lowers the fatigue limit, we not only simply control the residual stress in the abdomen, but also increase the strength of the abdomen and reduce the resistance of the rail itself (fatigue). It turns out that by raising the limit), it is possible to completely prevent this damage from occurring.
なお、第２図は硬頭（微細パーライト処理）レールのフ
ラッシュバット溶接部の垂直方向残留応力分布を示し、
（イ）がレール頭部、（口９が腹部、（−）が底部位置
での分布を示している。In addition, Figure 2 shows the vertical residual stress distribution of a flash butt weld of a hard-headed (fine pearlite treated) rail.
(a) shows the distribution at the rail head, (mouth 9 shows the abdomen, and (-) shows the distribution at the bottom position.
本発明はこの知見に基づいてなされｆこもので、その要
旨は溶接終了後ま１こは加熱に、！：リオーステナイト
状態にあるレール溶接部のレール全体またはレール頭部
と腹部を、高圧の気体源りは含水気体によってパーライ
ト変態が終了するまで冷却して高強度化し、その後、急
速冷却して圧縮残留応力を付与せしめてレール溶接部の
耐破壊特性を向上しようとするものである。The present invention was made based on this knowledge, and the gist of the invention is to heat the area immediately after welding is completed! : The whole rail or the rail head and abdomen of the rail welded part in the reaustenitic state is cooled with water-containing gas from a high-pressure gas source until pearlite transformation is completed to increase its strength, and then rapidly cooled to compress the remaining part. This is intended to improve the fracture resistance of rail welds by applying stress.
以下に本発明につい、て詳細に説明する。丑ず説明の便
宜上第１図（ａ）によりレール各部の名称を述べる。１
の範囲はレール頭部、２の範囲は腹部、３の範囲に底部
である。The present invention will be explained in detail below. For convenience of explanation, the names of each part of the rail will be described with reference to FIG. 1(a). 1
Range 2 is the rail head, range 2 is the abdomen, and range 3 is the bottom.
本発明は溶接終了後自己保有熱１ｆこに外部からの加熱
によＶ） Ａｒ、変態点以上の温度にあるレール溶接部
のレール全体またにレール頭部と腹部を、高圧の気体ま
りは含水気体によってパーライト変態が終了する丑で冷
却し、その後急速冷却するレール溶接部の耐破壊特性向
上法である。In the present invention, after the completion of welding, the self-retained heat 1f is heated from the outside (V) Ar, the entire rail at the rail welding part which is at a temperature above the transformation point, the rail head and the abdomen, and the high pressure gas chamber contains water. This is a method for improving the fracture resistance of rail welds by cooling with gas to complete pearlite transformation and then rapidly cooling.
本発明に於て、まず冷却開始前の温度をＡｒ、変態魚具
」二に設定する理由は、被冷却部をオーステナイト状態
力）ら急冷してパーライト変態させ、微細パーライト組
織を得て高強度化するためであり、そのためには冷却開
始前にＡｒ、変態点以上に保ってオーステナイト状態と
する必要がある。溶接後の自己保有熱によらず、外部か
らの加熱によｔ）Ａｒ。In the present invention, the reason why the temperature before the start of cooling is set to Ar is set to 2 is that the part to be cooled is rapidly cooled from the austenite state to pearlite and a fine pearlite structure is obtained, resulting in high strength. In order to do this, it is necessary to maintain the temperature above the transformation point using Ar before starting cooling to make the austenitic state. t)Ar by external heating, not by self-retained heat after welding.
変態以上とする場合、最高加熱温度に１３００℃以下と
することが望ましい。すなわち１３００℃を越えるよう
な温度に加熱すると結晶粒が粗大化して延性が低下し、
丑た焼割れが発生し易ぐなり、レールの耐久性が損なわ
れるからである。さらにこの場合レール溶接部の加熱範
囲はシー／１．頭部硬さの不均一の改善および耐摩耗性
の観点からレール頭部と、本損傷の発生個所である腹部
で良いが、これらの部分の抵抗力が高められると次にレ
ール底部からの破壊も懸念されるので、望ましくはレー
ル溶接部のレール全体が良い。またレールの長手方向に
は少なくとも溶接熱影響部を含む範囲がよい。When the temperature is higher than transformation, it is desirable that the maximum heating temperature is 1300°C or lower. In other words, when heated to a temperature exceeding 1300°C, the crystal grains become coarser and the ductility decreases.
This is because cracking is more likely to occur and the durability of the rail is impaired. Furthermore, in this case, the heating range of the rail weld is C/1. From the viewpoint of improving uneven head hardness and wear resistance, the rail head and the abdomen, where the main damage occurs, are good, but if the resistance of these parts is increased, then the rail bottom will be damaged. Therefore, it is preferable to use the entire rail at the rail welding part. Further, it is preferable that the longitudinal direction of the rail include at least the weld heat affected zone.
なお、上記温度範囲に加熱するには火焔あるいは、高周
波誘導加熱等を使用することが出来る。Note that flame, high frequency induction heating, or the like can be used to heat to the above temperature range.
溶接後の自己保有熱を利用する場合には溶接後、熱影響
部がオーステナイト状態にある間に冷却を開始しパーラ
イト変態を生じさせればよい。When using the self-retained heat after welding, cooling may be started after welding while the heat-affected zone is in the austenitic state to cause pearlite transformation.
高圧の気体″！、たに含水気体によってパーライト変態
が終了するまで冷却するのは、これらの冷媒で冷却する
ことによって微細パーライト組織を得るためである。こ
れらの冷媒より冷却速度の早い冷媒を用いると、マルテ
ンサイトが発生して被加熱部は脆化し、逆に冷却速度の
遅い冷媒を用いた場合、あるいは単なる空冷では、微細
パーライト組織を得ることが出来ず、高強度化されない
。The reason for cooling with high-pressure gas, especially water-containing gas, until pearlite transformation is completed is to obtain a fine pearlite structure by cooling with these refrigerants.Use a refrigerant with a faster cooling rate than these refrigerants. Then, martensite is generated and the heated part becomes brittle.On the other hand, if a refrigerant with a slow cooling rate is used or simply air cooling, a fine pearlite structure cannot be obtained and high strength cannot be achieved.
微細パーライト組織を得て高強度化するの（グ、最も良
好な耐摩耗性を得るためと、高強度化により高い疲労限
度とするためである。このためにはレール鋼としてＵ、
０．６５〜０８０％のＣを含有し、共析鋼あるいは共析
鋼に近い亜共析鋼であることが望捷しいが、微細パーラ
イト組織が得られれば特に成分を限定するものでにない
。The purpose is to obtain a fine pearlite structure and increase the strength (g), in order to obtain the best wear resistance and to achieve a high fatigue limit by increasing the strength.For this purpose, as a rail steel, U,
A eutectoid steel or a hypo-eutectoid steel that contains 0.65 to 080% C and is close to eutectoid steel is desirable, but there is no particular restriction on the composition as long as a fine pearlite structure can be obtained. .
パーライト変態終了後急速冷却する理由は、出来るだけ
大きい圧縮残留応力を得るためである。。The reason for rapid cooling after pearlite transformation is to obtain as large a compressive residual stress as possible. .
なお、この場合、室温まで急冷しても良いが、約２００
℃位まで急冷し、その後放冷してもかまわない。急冷後
の室温における硬さＨＨ，ｖ ３３０以上であることが
望ましい。In this case, it may be rapidly cooled to room temperature, but the
It is also possible to rapidly cool it to around ℃ and then leave it to cool. It is desirable that the hardness at room temperature after quenching is HH,v 330 or more.
残留応力に平均応力として作用するため、圧縮の残留応
力は疲労強度に効果的に作用し、疲労限度を向上させる
。Since the residual stress acts as an average stress, the compressive residual stress effectively acts on the fatigue strength and improves the fatigue limit.
以上の如く、本発明を施したレールの溶接部は微細パー
ライト組織を呈して高強度化し、かつ圧縮残留応力が付
与されているために疲労限度が非常に向上し、耐破壊特
性が一層向上している。As described above, the welded part of the rail according to the present invention exhibits a fine pearlite structure and has high strength, and because compressive residual stress is applied, the fatigue limit is greatly improved and the fracture resistance is further improved. ing.
つぎに本発明の一実施例を述べる。Next, one embodiment of the present invention will be described.
ＡＲＥＡ １３６ ｌｂの硬頭（微細パーライト処理）
１／−ルを用いて、フラッシュバット溶接を行イ、−た
ん室温まで冷却して余盛を≠８０グラインダーで研削、
削除した。その後熱影響部を含むレール溶接部のレール
全体をガス火焔により９００℃に加熱した後、高圧の空
気によりパーライト変態が終了する５７０℃位まで冷却
し、その抜水を噴出して室温まで急速冷却を行った。そ
の結果、第１表中に示す如く、本発明レールは頭部、腹
部および底部が高強度化し、さらに大きな圧縮残留応力
が付与されている。腹部のき裂再現実験（繰返し荷重Ｐ
鯨２！５ｔ 、 Ｐ ”’ ５ ｔ＋繰返し数４００万
回までの３点曲げ疲労試験、スパン１ｍ）の結果、従来
レール（微細パーライト処理レールをフラッシュバット
溶接後、余盛を≠８０グラインダーで研削削除しり寸＼
のレール）にはき裂発生が認められるのに対し、本発明
レールはき裂発生に認められず、耐破壊性が非常に優れ
ていることがわかる。AREA 136 lb hard head (fine pearlite treatment)
Perform flash butt welding using a 1/- tool, cool to room temperature, and grind the excess with a ≠80 grinder.
Deleted. After that, the entire rail at the rail weld including the heat-affected zone is heated to 900℃ with a gas flame, and then cooled with high-pressure air to about 570℃, where pearlite transformation ends, and the drained water is spouted out to quickly cool it to room temperature. I did it. As a result, as shown in Table 1, the rail of the present invention has high strength at the head, abdomen, and bottom, and is endowed with even greater compressive residual stress. Abdominal crack reproduction experiment (repetitive load P
Kujira 2!5t, P''' 5t + 3-point bending fatigue test up to 4 million repetitions, span 1m) The results of the conventional rail (after flash butt welding the fine pearlite treated rail, the excess was ground with a ≠80 grinder) Delete butt size＼
While cracks were observed in the rail of the present invention, no cracks were observed in the rail of the present invention, indicating that it has extremely excellent fracture resistance.
第１図（ａ）はレール正面図、第１図（ｂ）はレールき
裂発生状況の説明図、第２図はレール溶接部の垂直方向
残留応力分布図である。
１・・・レール頭部、２・・・腹部、３・・・底部、４
・・・溶接部、５・・・き装発生起点、６・・・き裂。
特許出願人 代理人
弁理士 矢 葺 知 之
（ほか１名）
第１図
（（Ｚ）FIG. 1(a) is a front view of the rail, FIG. 1(b) is an explanatory diagram of the occurrence of rail cracks, and FIG. 2 is a vertical residual stress distribution diagram of the rail welded portion. 1...Rail head, 2...Abdomen, 3...Bottom, 4
...Welded part, 5... Starting point of cracking, 6... Crack. Patent applicant Representative patent attorney Tomoyuki Yafuki (and 1 other person) Figure 1 ((Z)
Claims (1)
ｒ１変態点以上の温度にあるレール溶接部のレール全体
またはレール頭部と腹部を高圧の気体または含水気体に
よってパーライト変態が終了するまで冷却し、その後、
急速冷却することを特徴とするレール溶接部の耐破壊特
性向上法。A due to self-retained heat after welding or external heating
The entire rail or the rail head and abdomen of the rail welded portion, which is at a temperature higher than the r1 transformation point, is cooled by high-pressure gas or water-containing gas until the pearlite transformation is completed, and then,
A method for improving the fracture resistance of rail welds, which is characterized by rapid cooling.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP20199682A JPS5993838A (en) | 1982-11-19 | 1982-11-19 | Improvement of fracture resistance of weld zone of rail |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP20199682A JPS5993838A (en) | 1982-11-19 | 1982-11-19 | Improvement of fracture resistance of weld zone of rail |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPS5993838A true JPS5993838A (en) | 1984-05-30 |
Family
ID=16450206
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP20199682A Pending JPS5993838A (en) | 1982-11-19 | 1982-11-19 | Improvement of fracture resistance of weld zone of rail |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS5993838A (en) |
Cited By (10)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH02282426A (en) * | 1989-04-21 | 1990-11-20 | Nippon Steel Corp | Manufacture of rail having excellent brittle crack developing resistant characteristic |
| JPH0810980A (en) * | 1994-06-23 | 1996-01-16 | Elpatronic Ag | Method and device for after-treatment of welded sheet metal |
| JP2010188382A (en) * | 2009-02-18 | 2010-09-02 | Nippon Steel Corp | Method of cooling weld zone of rail |
| WO2010109837A1 (en) | 2009-03-27 | 2010-09-30 | 新日本製鐵株式会社 | Device and method for cooling welded rail section |
| WO2010116680A1 (en) | 2009-03-30 | 2010-10-14 | 新日本製鐵株式会社 | Method of cooling welded rail section, device for cooling welded rail section, and welded rail joint |
| JP2015507080A (en) * | 2011-11-29 | 2015-03-05 | シーエフ アンド アイ スチール エル．ピー．， ディー／ビー／エー エブラズ ロッキー マウンテン スチール | Method and apparatus for the treatment of rail welds |
| CN108570550A (en) * | 2018-05-18 | 2018-09-25 | 攀钢集团攀枝花钢铁研究院有限公司 | Heat treatment type bainite rail welding point post weld heat treatment method |
| US10144983B2 (en) | 2011-05-25 | 2018-12-04 | Nippon Steel and Sumitomo Metal Corporation | Method of reheating rail weld zone |
| US10526674B2 (en) | 2012-11-16 | 2020-01-07 | Nippon Steel Corporation | Stress-relief heat treatment apparatus |
| US10544479B2 (en) | 2014-04-08 | 2020-01-28 | Nippon Steel Corporation | Heat treatment device, heat treatment method, and rail steel |
-
1982
- 1982-11-19 JP JP20199682A patent/JPS5993838A/en active Pending
Cited By (18)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH02282426A (en) * | 1989-04-21 | 1990-11-20 | Nippon Steel Corp | Manufacture of rail having excellent brittle crack developing resistant characteristic |
| JPH0810980A (en) * | 1994-06-23 | 1996-01-16 | Elpatronic Ag | Method and device for after-treatment of welded sheet metal |
| JP2010188382A (en) * | 2009-02-18 | 2010-09-02 | Nippon Steel Corp | Method of cooling weld zone of rail |
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