JPS62227040A - Improvement of resistance to impact fracture of weld zone of rail - Google Patents
Improvement of resistance to impact fracture of weld zone of railInfo
- Publication number
- JPS62227040A JPS62227040A JP7058886A JP7058886A JPS62227040A JP S62227040 A JPS62227040 A JP S62227040A JP 7058886 A JP7058886 A JP 7058886A JP 7058886 A JP7058886 A JP 7058886A JP S62227040 A JPS62227040 A JP S62227040A
- Authority
- JP
- Japan
- Prior art keywords
- rail
- weld zone
- temp
- resistance
- transformation
- 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
- 230000009466 transformation Effects 0.000 claims abstract description 22
- 229910000734 martensite Inorganic materials 0.000 claims abstract description 16
- 238000001816 cooling Methods 0.000 claims abstract description 15
- 229910001562 pearlite Inorganic materials 0.000 claims abstract description 11
- 238000010438 heat treatment Methods 0.000 claims abstract description 10
- 210000001015 abdomen Anatomy 0.000 claims description 11
- 238000003466 welding Methods 0.000 claims description 6
- 238000000034 method Methods 0.000 claims description 3
- 238000010791 quenching Methods 0.000 description 4
- 238000005496 tempering Methods 0.000 description 4
- 238000010586 diagram Methods 0.000 description 3
- 238000012360 testing method Methods 0.000 description 3
- 230000000694 effects Effects 0.000 description 2
- 239000007788 liquid Substances 0.000 description 2
- 230000000171 quenching effect Effects 0.000 description 2
- 238000011160 research Methods 0.000 description 2
- 230000035939 shock Effects 0.000 description 2
- 238000010998 test method Methods 0.000 description 2
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 2
- 244000025254 Cannabis sativa Species 0.000 description 1
- 241000282342 Martes americana Species 0.000 description 1
- 239000003795 chemical substances by application Substances 0.000 description 1
- 238000005336 cracking Methods 0.000 description 1
- 239000013078 crystal Substances 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 230000006698 induction Effects 0.000 description 1
- 230000000977 initiatory effect Effects 0.000 description 1
- 238000009434 installation Methods 0.000 description 1
- 238000011835 investigation Methods 0.000 description 1
- 238000012423 maintenance Methods 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 239000003507 refrigerant Substances 0.000 description 1
- 238000010583 slow cooling Methods 0.000 description 1
Landscapes
- Heat Treatment Of Articles (AREA)
Abstract
Description
【発明の詳細な説明】
（産業上の利用分野）
本発明は軌条溶接部の耐価準破壊特性の向上法に関する
ものである。DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method for improving quasi-fracture resistance of a rail weld.
（従来の技術、及び発明が解決しようとする問題点）軌
条の継目部は列車通過による則ｆ撃および振動などのた
めに、軌条および継目板等に損傷が発生しやすく、保守
管理上問題があシ、さらに乗心地も悪いことから、最近
は溶接によるロング化が図られている。その結果、軌条
損傷も減少傾向にあシ、また快適な乗心地が得られるよ
うになってきたＯ
しかし、溶接部には溶接時の熱影響によシ軌条頭部硬さ
の不均一部の発生は避は難く、敷設後の摩耗などにより
凹凸が発生し、列車通過の際若干の衝撃荷重がかかる。(Prior art and problems to be solved by the invention) Rail joints are prone to damage due to regular shock and vibration caused by passing trains, which poses problems in terms of maintenance and management. Since the legs and riding comfort are also poor, recent attempts have been made to lengthen them by welding. As a result, rail damage has been decreasing, and a more comfortable ride has been achieved. This is unavoidable, and unevenness occurs due to wear and other factors after installation, and some shock loads are applied when trains pass.
その結果、軌条溶接部に於て、頭頂面からころがシ損傷
が発生したりあるいは底部から疲労き裂が発生し、これ
らを起点に横裂に至る場合がしばしば見られている。As a result, it is often seen that roller damage occurs from the top surface of the rail weld, or fatigue cracks occur from the bottom, which then lead to transverse cracks.
ところが、最近ではより輸送の効率化を自損して、列車
のスピードアップ化および高軸重化が図られつつある。However, recently, efforts have been made to speed up trains and increase their axle loads, at the expense of improving transportation efficiency.
このようなすう勢だあって最も懸念される問題が、列車
通過時の衝撃荷重で軌条が横裂や複数個の破片に***す
る複雑破壊に呈シ。Given this trend, the most worrisome problem is complex fractures in which the rails crack horizontally or split into multiple pieces due to the impact load caused by passing trains.
その結果列車の脱線事故を引き起こすことである。As a result, train derailment accidents occur.
これらは重大事故に連がる可能性が高いだけに、軌条の
耐衝撃荷重破壊性に対する要求が年々高まりつつある・
しかしながら、従来軌条の溶接部については、軌条頭部
の軟化防止や硬頭化および溶接欠陥の防止等に、主に研
究が向けられ、耐衝草破壊性に関する研究は特開昭５９
−９３８３７号公報、特開昭５９−９３８３８号公報な
どで報告されているが、その数は少ない。Since these are likely to lead to serious accidents, the demand for rails to withstand impact loads and breakage is increasing year by year.
However, with regard to the welded parts of conventional rails, research has mainly focused on preventing the rail head from softening, hardening, and welding defects, and research on impact grass fracture resistance was conducted in JP-A-59
Although it has been reported in Japanese Patent Application Laid-Open No. 59-93837 and Japanese Unexamined Patent Publication No. 59-93838, the number of such cases is small.
そこで本発明者らは、上記の如き問題点に対し、軌条溶
接部の破壊靭性値の改善を図るべく、種々調査、研究を
行った。その結果、破壊靭性値は焼戻しマルテンサイト
組織にすれば著しく改善でき。Therefore, the present inventors conducted various investigations and studies in order to improve the fracture toughness value of the rail welded portion in order to address the above-mentioned problems. As a result, the fracture toughness value can be significantly improved by using a tempered martensitic structure.
−４０℃程度までは脆性破壊【２ないことがわかった。It was found that there was no brittle fracture [2] up to about -40°C.
しかし、焼戻しマルテンサイト組織は軌条の耐摩耗性や
耐損傷性が・ぐ−ライトＭｉ織や微細・クーライト組織
よυ劣ることが知られている。そこで、軌条頭部のみは
１ｌｌｉｔ摩耗性および耐損傷性を付与しながら、＃重
荷重に対する脆性き裂の発生、進展を防止するには、軌
条頭部のみはパーライト組織おるいは微細パーライト組
織とするが、脆性き裂の発生、進展部位となる軌条腹部
または底部あるいはこれらの両方を焼戻しマルテンサイ
ト組織にして脆性破壊を防止すればよいことがわかった
。However, it is known that the tempered martensitic structure has inferior rail wear resistance and damage resistance to that of the fine-light Mi weave and the fine-coolite structure. Therefore, in order to prevent the occurrence and propagation of brittle cracks under heavy loads while imparting 1llit wear resistance and damage resistance to only the rail head, it is necessary to make only the rail head a pearlite structure or a fine pearlite structure. However, it has been found that brittle fracture can be prevented by creating a tempered martensitic structure in the rail abdomen or bottom, or both, where brittle cracks occur and propagate.
（問題点を解決するための手段）
本発明は上記の如き知見に基づいてなされたもので、そ
の主旨は溶接終了後の自己保有熱、または外部からの加
熱によりＡｔ変態点を越え、１３００℃以下の温度にあ
る軌条溶接部の頭部をパーライト組織または微細ノや−
ライト組織を呈する速さで冷却しつつ、軌条腹部または
底部あるいはこれら両方を、急速冷却してマルテンサイ
ト変態を起こさせた後、さらに軌条の腹部または底部あ
るいはこれらの両方を４００℃以上Ａ１変態点を越えな
い＠夏に加熱後、直ちに急速冷却する軌条溶接部の耐衝
撃破壊特性向上法であ、る。(Means for Solving the Problems) The present invention has been made based on the above-mentioned knowledge, and the gist thereof is to exceed the At transformation point by self-retained heat after welding or by external heating, and to reach a temperature of 1300°C. The head of the rail weld at a temperature of
After rapidly cooling the abdomen and/or the bottom of the rail to cause martensitic transformation while cooling at a rate at which a light structure is exhibited, the abdomen and/or the bottom of the rail are further heated to 400°C or above the A1 transformation point. This is a method for improving the impact fracture resistance of rail welds, which involves rapid cooling immediately after heating in the summer.
以下に本発明について詳細に説明する〇第１図は本発明
の説明に先立ち、軌条各部の名称を述べたものである。The present invention will be explained in detail below. Figure 1 describes the names of various parts of the rail before explaining the present invention.
図中１は頭部、２は腹部、３は底部である。In the figure, 1 is the head, 2 is the abdomen, and 3 is the bottom.
本発明は溶接終了後の自己保有熱によりＡｔ変態点を越
え１３００℃以下の温度にある軌条溶接部、または高周
波誘導加熱あるいは、ガス加熱等の熱媒で該温度に加熱
された軌条溶接部の頭部をパーライト組ｎｌＦｃまたは
微細パーライト組織を呈する速さで冷却しつつ、腹部ま
たは底部あるいはこれら両方を、急速冷却して焼入れを
行いマルテンサイト変態を起こさせる。つぎに続いて腹
部または底部あるいはこれら両方の焼入れ部を４００℃
以上Ａ１変態点を越えない温度に加熱して焼戻しを行い
・その後直ちに急速冷却を行うものである。The present invention is applicable to rail welds whose temperature exceeds the At transformation point and is below 1300°C due to self-retained heat after welding, or which is heated to this temperature with a heating medium such as high-frequency induction heating or gas heating. While the head is cooled at a rate at which a pearlite structure nlFc or a fine pearlite structure is formed, the abdomen or the bottom, or both, are rapidly cooled and quenched to cause martensitic transformation. Next, the abdomen and/or bottom part is quenched at 400°C.
Tempering is performed by heating to a temperature that does not exceed the A1 transformation point, and then rapid cooling is performed immediately.
まず焼入れの際の冷却開始温度範囲をＡ１変態点を越え
、１３００℃以下に設定する理由について述べる。冷却
開始最低温度がＡｔ変態点を越えなければならない理由
は、被熱処理部分をオーステナイト化せしめた後、急速
冷却してマルテンサイト変態を起こさせるためである。First, the reason why the cooling start temperature range during quenching is set above the A1 transformation point and below 1300°C will be described. The reason why the minimum cooling start temperature must exceed the At transformation point is that after the heat-treated portion is austenitized, it is rapidly cooled to cause martensitic transformation.
冷却開始最高温度を１３００℃以下に設定する理由は１
３００℃を越える高い温度から急速冷却すると焼割れが
発生しやすく、また結晶・粒が粗大となり延性が低下す
るためである。The reason for setting the maximum cooling start temperature below 1300℃ is 1.
This is because rapid cooling from a high temperature exceeding 300° C. tends to cause quench cracking, and the crystals and grains become coarse, reducing ductility.
急速冷却する理由はマルテンサイト変態を起こさせるた
めで、圧縮空気等による緩冷却ではマルテンサイト変態
が起こらず、パーライト変態してしまうためである。冷
媒は水またはンリグル液等を使用することが出来る。The reason for rapid cooling is to cause martensitic transformation, and slow cooling with compressed air or the like does not cause martensitic transformation and results in pearlite transformation. As the refrigerant, water, liquid, etc. can be used.
次に、焼入れ部を焼戻しする際の加熱温度範囲を４００
℃以上Ａ！変態点を越えない温度に設定する理由につい
て述べる。焼戻し温度を４００℃以上とする理由は延性
のある焼戻しマルテンサイト組織を得るためのもので、
４００℃未満ではマルテンサイト組織が十分に焼戻しさ
れずに、不均質な焼戻しマルテンサイト組織となり、良
好な破壊靭性値が得られないためである。Ａ、変態点を
越えない温度に設定する理由は、Ａ１変態点を越えると
オーステナイト化してしまい、折角、前記焼入れ処理に
よって得られたマルテンサイト組織が消滅してしまうた
めである。Next, the heating temperature range when tempering the hardened part is set to 400°C.
℃ or more A! The reason why the temperature is set so as not to exceed the transformation point will be explained. The reason why the tempering temperature is set to 400°C or higher is to obtain a ductile tempered martensitic structure.
This is because if the temperature is lower than 400°C, the martensite structure is not sufficiently tempered, resulting in a non-uniform tempered martensite structure, making it impossible to obtain a good fracture toughness value. A. The reason why the temperature is set at a temperature that does not exceed the transformation point is that if the temperature exceeds the A1 transformation point, it will become austenitic and the martensitic structure obtained by the quenching treatment will disappear.
焼戻し後、直ちに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。この場合、室温まで
急速冷却してもよいが、約２００℃位まで急速冷却し、
その後放冷してもかまわない。The reason for rapid cooling immediately after tempering is to obtain as large a compressive residual stress as possible. In this case, it may be rapidly cooled to room temperature, but it may be rapidly cooled to about 200℃,
You can leave it to cool afterwards.
残留応力は平均応力として作用するので、脆性破壊特性
にも影響を及ぼすことが知られている。Since residual stress acts as an average stress, it is known that it also affects brittle fracture characteristics.
すなわち、引張残留応力は悪影響を及ぼし、圧縮残留応
力は効果的に脆性破壊特性に作用する。本発明では、こ
の圧縮残留応力の効果の活用をもねらったものである。That is, tensile residual stress has a negative effect, while compressive residual stress effectively affects brittle fracture properties. The present invention also aims to utilize the effect of this compressive residual stress.
以上のごとく、本発明による熱処理を施された軌条溶接
部は脆性き裂の発生、進展の恐れのある部分を焼戻しマ
ルテンサイト組織として脆性破壊の発生、進展の防止を
組織上から図ると同時に。As described above, the rail welded part that has been heat treated according to the present invention has a tempered martensitic structure in areas where there is a risk of brittle crack initiation and propagation, thereby preventing the occurrence and propagation of brittle fracture from the structural point of view.
これら該部分に圧縮残留応力も付与して、より 一層軌
条自身の＠唯破壊抵抗性を高めたものである。Compressive residual stress is also applied to these parts, further increasing the fracture resistance of the rail itself.
（実施例） 次に、本発明の一実施例について述べる。(Example) Next, one embodiment of the present invention will be described.
フランシーバット溶接後、パリ取りを行い約８５０℃の
温度にあるＡＲＥＡ １３６ｔｂ軌条について、軌条頭
部は圧縮空気によ＃）パーライト変態が終了する５７０
℃まで冷却し、ぞの後室温まで急冷する通常のスラッゾ
・クエンチを行い、軌条腹部および底部についてはソリ
プル液によ）室温まで急速冷却し、その後腹部および底
部をガス炎により５５０℃加熱後、水により急速冷却を
行った。その結果、軌条頭部は第２図に示す顕微鏡金属
組織写真に示すように耐摩耗性および耐損傷性の良好な
微細・ｌ−ライト組織となり、軌条腹部および底部は第
３図に示す顕微鏡金属組織写真に示すように破壊靭性の
良好な焼戻しマルテンサイ）Ｍ織となった０
本発明軌条溶接部について、衝撃破壊抵抗性を調べるた
めに、第４図に示す如く軌条底部横断面に全幅にわたっ
て半径５＋ｍ、深さ５簡の半円切欠きを付け、この切欠
き部がスパン１ｍの中央部に位置するようにセットし、
１ ｔｏｎｆの重錘ｆ ４．２ ｍの高さから落下させ
て破断の有・無を調べる落電試験を室温で行った。その
結果、第１表から明らかなように、従来の溶接ままの軌
条および軌条溶接後頭部のみを微細ノ臂−ライト化熱処
理された軌条はいずれも破断したのに対し１本発明軌条
は破断せず、衝撃破壊抵抗性が非常に優れていることが
わかる。After Francie butt welding, the AREA 136tb rail is deburred and the temperature is about 850℃, and the rail head is heated with compressed air to complete the pearlite transformation.
℃, followed by the usual sludzo quench, in which the abdomen and bottom of the rail were rapidly cooled to room temperature (with Solipul liquid), and then the abdomen and bottom were heated to 550℃ with a gas flame. Rapid cooling was performed with water. As a result, the rail head has a fine l-lite structure with good wear resistance and damage resistance, as shown in the microscopic metallographic photograph shown in Figure 2, and the rail abdomen and bottom have a microscopic metal structure as shown in Figure 3. As shown in the microstructure photograph, in order to investigate the impact fracture resistance of the welded part of the rail of the present invention, which has become a tempered marten weave (M weave) with good fracture toughness, a radius was Attach a semicircular notch of 5 + m and depth of 5 cm, and set it so that this notch is located at the center of the 1 m span.
An electric drop test was conducted at room temperature by dropping a weight of 1 tonf from a height of 4.2 m to check for breakage. As a result, as is clear from Table 1, both the conventional as-welded rail and the rail in which only the welded back of the rail was heat-treated to make the back part of the rail finely lightened broke, whereas the rail of the present invention did not break. It can be seen that the impact fracture resistance is very good.
第１表
本発明軌条と従来軌条溶接部の落雷試験結果の比較（試
１倹温度；室温）Table 1 Comparison of lightning test results of the inventive rail and conventional rail welded parts (Test 1 temperature: room temperature)
第１図は軌条各部の名称を説明する説明図、第４図（イ
）は実施例における落雷試験方法を示す図で、同（ロ）
は（イ）のＡ部の拡大図、同（ハ）は同正面図である。
に軌条頭部、 ２：軌条腹部、
３：軌条底部。
第１図
−二″ｆ・、ハ ′、、 ；′］、 ＋ 二′〜ノ“
パフ・第 ２［′４
第３図
１、、、＝、ｊ
７ろ消
昭和６１年特許願第７００Ｓ号
３、補正をする者
氏 名（８称） ＼」１１１本製鐵（朱式會社４、代理
人
住 所 東京都千代田区丸の内２丁＠６番２号丸の内
へ重洲ビル３３Ｇ氏名 （３６６７）谷山輝雄Ｆ］
本願明細書及び図面中下記事環を補正いたします。
記
１、第９頁下かも５行目
「顕微鏡金属組織を示す写真の複写図、」とあるを
−「顕微鏡金属組織を示す写真、」と訂正する。
２、図面中「第２図」、「第３図」を別紙の如く訂正す
る。Figure 1 is an explanatory diagram explaining the names of each part of the rail, Figure 4 (a) is a diagram showing the lightning test method in the example, and Figure 4 (b) is a diagram showing the lightning test method in the example.
is an enlarged view of part A in (a), and (c) is a front view of the same. 2: Rail head, 3: Rail bottom. FIG.
Puff No.2 4. Agent address: 2-chome Marunouchi, Chiyoda-ku, Tokyo @ 6-2 Marunouchi Shigesu Building 33G Name (3667) Teruo Taniyama F] We would like to amend the following circles in the specification and drawings. In the 5th line at the bottom of page 9, the statement ``A copy of a photo showing a microscopic metallographic structure,'' should be corrected to ``A photo showing a microscopic metallographic structure.'' 2. In the drawings, ``Figure 2'' and ``Figure 3'' ” shall be corrected as shown in the attached sheet.
Claims (1)
、Ａ＿１変態点を越え、１３００℃以下の温度にある軌
条溶接部の頭部をパーライト組織または微細パーライト
組織を呈する速さで冷却しつつ、軌条腹部または底部あ
るいはこれら両方を、急速冷却してマルテンサイト変態
を起こさせた後、さらに腹部または底部あるいはこれら
両方の部分を４００℃以上Ａ＿１変態点を越えない温度
に加熱後、直ちに急速冷却することを特徴とする軌条溶
接部の耐衝撃破壊特性向上法。While cooling the head of the rail welded part, which has exceeded the A_1 transformation point and is at a temperature of 1300 ° C. or less, by self-retained heat after welding or external heating at a rate at which it exhibits a pearlite structure or a fine pearlite structure, After rapidly cooling the rail abdomen and/or bottom to cause martensitic transformation, further heating the abdomen and/or bottom to a temperature of 400°C or higher but not exceeding the A_1 transformation point, and then immediately cooling rapidly. A method for improving impact fracture resistance of rail welded parts.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP7058886A JPS62227040A (en) | 1986-03-28 | 1986-03-28 | Improvement of resistance to impact fracture of weld zone of rail |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP7058886A JPS62227040A (en) | 1986-03-28 | 1986-03-28 | Improvement of resistance to impact fracture of weld zone of rail |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPS62227040A true JPS62227040A (en) | 1987-10-06 |
Family
ID=13435868
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP7058886A Pending JPS62227040A (en) | 1986-03-28 | 1986-03-28 | Improvement of resistance to impact fracture of weld zone of rail |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS62227040A (en) |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2008088834A1 (en) * | 2007-01-17 | 2008-07-24 | Kva, Inc. | Method for improving the performance of seam-welded joints using post-weld heat treatment |
| JP4757955B2 (en) * | 2009-03-27 | 2011-08-24 | 新日本製鐵株式会社 | Rail welding section cooling device and cooling method |
| JP2012030242A (en) * | 2010-07-29 | 2012-02-16 | Nippon Steel Corp | Post-heat treatment method for weld zone of rail |
| 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 |
-
1986
- 1986-03-28 JP JP7058886A patent/JPS62227040A/en active Pending
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2008088834A1 (en) * | 2007-01-17 | 2008-07-24 | Kva, Inc. | Method for improving the performance of seam-welded joints using post-weld heat treatment |
| JP4757955B2 (en) * | 2009-03-27 | 2011-08-24 | 新日本製鐵株式会社 | Rail welding section cooling device and cooling method |
| US8353443B2 (en) | 2009-03-27 | 2013-01-15 | Nippon Steel Corporation | Device and method for cooling rail weld zone |
| JP2012030242A (en) * | 2010-07-29 | 2012-02-16 | Nippon Steel Corp | Post-heat treatment method for weld zone of rail |
| 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 |
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