JP3787622B2 - Reinforcement welding method to suppress weld cracking - Google Patents
Reinforcement welding method to suppress weld cracking Download PDFInfo
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- JP3787622B2 JP3787622B2 JP2002262236A JP2002262236A JP3787622B2 JP 3787622 B2 JP3787622 B2 JP 3787622B2 JP 2002262236 A JP2002262236 A JP 2002262236A JP 2002262236 A JP2002262236 A JP 2002262236A JP 3787622 B2 JP3787622 B2 JP 3787622B2
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- 238000003466 welding Methods 0.000 title claims description 119
- 238000000034 method Methods 0.000 title claims description 40
- 230000002787 reinforcement Effects 0.000 title claims description 17
- 238000005336 cracking Methods 0.000 title description 5
- 239000000463 material Substances 0.000 claims description 34
- 230000009466 transformation Effects 0.000 claims description 24
- 230000003014 reinforcing effect Effects 0.000 claims description 13
- 230000000694 effects Effects 0.000 description 6
- 239000007789 gas Substances 0.000 description 6
- 238000010438 heat treatment Methods 0.000 description 3
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 description 2
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 description 2
- 229910000831 Steel Inorganic materials 0.000 description 1
- 229910052786 argon Inorganic materials 0.000 description 1
- 230000001174 ascending effect Effects 0.000 description 1
- 229910002092 carbon dioxide Inorganic materials 0.000 description 1
- 239000001569 carbon dioxide Substances 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 238000001816 cooling Methods 0.000 description 1
- 230000007423 decrease Effects 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 230000017525 heat dissipation Effects 0.000 description 1
- 229910000734 martensite Inorganic materials 0.000 description 1
- 238000002844 melting Methods 0.000 description 1
- 230000008018 melting Effects 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 239000010959 steel Substances 0.000 description 1
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Description
【発明の属する技術分野】
この出願の発明は大きい溶接部疲労強度を必要とする溶接構造物の補強溶接方法に関するものである。さらに詳しくは、この出願の発明は低変態温度溶接材料を使用する補強溶接方法において、溶接割れの発生を抑制する溶接方法に関するものである。
【従来の技術とその課題】
従来から構造物の溶接や補修時の溶接に際しては、冷却に伴う熱収縮によって溶接部に引張りの残留応力が誘起されて溶接部の疲労強度が低下するという問題が避けられなかった。
この課題を解決するために、この出願の発明者は溶接が完了する室温もしくはその付近の温度でマルテンサイト変態膨張が終了する溶接材料、いわゆる低変態温度溶接材料と不活性のシールドガスを使用する「溶接方法」を提案しており、これらはすでに特許登録されている（特許第３０１０２１１号）。
この新しい「溶接方法」によって溶接構造物の疲労強度は著しく改善された。しかしながら、この低変態温度溶接材料は、補強溶接によって溶接部近傍への圧縮残留応力の導入により疲労強度を向上させようとする場合、補強部位において、繰り返し高温加熱されると溶接割れ（Weld Crack）を生じることがある。
従来一般の溶接方法では繰り返し加熱されても溶接割れが発生しない溶接材料を使用していたため、溶接された後の溶接部の形状には注意が払われていたが溶接材料の繰り返し加熱についてはほとんど関心が払われてこなかった。
したがって、溶接疲労強度を改善するために低変態温度溶接材料を使用する場合でも、溶接方法は従来の溶接方法と同じく溶接部材に対して繰り返し加熱する方法がそのまま採用されることがあるため、低変態温度溶接材料の使用によって、溶接疲労強度が向上することが期待されるにもかかわらず、溶接部に溶接割れが発生することにより、その効果を充分に発揮することができないという事態が生じる。
そこで、この出願の発明は、以上の事情に鑑みてなされたものであって、発明者が提案し、実際的にも優れた効果が得られている低変態温度溶接材料の特徴を生かし、溶接割れの発生を抑制して溶接部の疲労強度を確実に向上することができる新しい補強溶接方法を提供することを課題としている。
【課題を解決するための手段】
この出願の発明は、上記の課題を解決するためのものとして、第１には、低変態温度溶接材料を使用する補強溶接方法において、低変態温度溶接材料に溶接温度による熱履歴を回避しながら溶接する方法を提供する。また、第２には、低変態温度溶接材料を使用する補強溶接方法において、水平附加構造物の端部溶接止端部の上側から側面を経由して下側を溶接する方法を、第３には、溶接線が直線状になるように移動させながら溶接する方法を、また、第４には、溶接方法が低変態温度溶接材料を使用するアーク溶接であることを特徴とする方法を提供する。
【発明の実施の形態】
この出願の発明は上記のとおりの特徴をもつものであるが、以下にその実施の形態について説明する。まずなによりも特徴的なことは、この出願の発明は低変態温度溶接材料を使用する補強溶接方法において、溶接材料に対して繰り返し加熱するような、いわゆる高温履歴を避けることである。
たとえば、従来の溶接方法で垂直の構造体に水平方向の板状体を溶接する場合、溶落を防止し、溶接部の溶接形状を重視するために水平方向の板状体の下側から溶接を開始して溶接線を鉄道がスイッチバックするように左右に振りながら上昇させて板状体の上側まで溶接する方法が採用されてきた。このように従来の溶接方法は溶接線を左右に振りながら下側から上方に向かって順次溶接材を積み上げるようにして溶接するため一旦冷却されかかった下側の溶接材がその上側を通る溶接線によって加熱が繰り返されていた。そして、従来の溶接材料を使用する場合はこのような溶接方法で何ら問題はなかった。
しかしながら、溶接材料として低変態温度溶接材料を使用する場合にこのような溶接方法をそのまま適用すると低変態温度溶接材料が繰り返し加熱を受けて溶接割れを生じやすく、本来の疲労強度を向上する効果を充分に実現できないことがある。
図３及び図４はこの出願の発明と比較するために、低変態温度溶接材料を使用するものの、従来の補強溶接方法で溶接する時の態様を示したものである。図４は垂直構造物（Ａ）に附加構造物（Ｂ）が溶接されている状態を示す側面図である。そして（１）は既溶接部材であり、（２）は補強溶接部材である。図３は図４の左側正面から見た時の模式図であり、水平附加構造物（Ｂ）の周囲は既溶接部材（１）で溶接されており、その既溶接部材（１）の周囲は低変態温度溶接材料からなる補強溶接部材（２）で被覆されている。
そして、図３で示す従来の補強溶接方法は、まず水平附加構造物（Ｂ）の下側（４）を溶接した後、溶接線（３）を鉄道が急坂を登る時にスイッチバックするような経路で下方から上方へ移動しながら側面（６）を溶接して上側の端部（７）に達した後に上側（８）を溶接する。
この補強溶接方法は溶接線（３）を左右に振りながら上昇する過程で、一旦冷却されかかった下側の溶接部材がその上側を通る溶接線（３）によって熱を繰り返し受けるため補強溶接部が溶接割れ（９）を生じる原因となっていた。
そこで、この出願の発明は溶接に際し熱履歴をなるべく受けないように従来とは逆に板状体の溶接部の上側から溶接を開始して溶接線が直線状になるように下降させながら溶接し最後に下側を溶接する。
なお、上側から下側に向かって溶接するのは、低変態温度溶接材料の粘性が高く溶落しにくい性質を利用することと、この方が操作も簡便であり放熱効果も良好なためである。
図１及び図２はこの出願の発明による溶接方法を示したものである。図１は図２の左側正面から見た模式図であり、水平附加構造物（Ｂ）の周囲は既溶接部材（１）で溶接されており、その既溶接部材（１）の周囲は低変態温度溶接材料からなる補強溶接部材（２）で被覆されている。この出願の発明の補強溶接方法では、図３で示した従来の溶接方法とは逆に水平附加物（Ｂ）の上側（８）を溶接した後、溶接線（３）の矢印で示すように、附加物の側面（６）に沿って下向きに直線状に溶接し、溶接線（３）が附加物の下側端部（５）に達した後に下側（４）を補強溶接する。
すなわち、この出願の溶接方法は従来の溶接法のように溶接を下側から始め溶接線を鉄道のスイッチバックの様に左右に振りながら上昇させて順次溶接材を積み上げるようにして溶接する方法ではなく、上方から下方に向けて一直線に溶接するため低変態温度溶接材料に対する熱履歴がなく、溶接割れを防止することができる。
しかも低変態温度溶接材料を使用しているので溶接部近傍に誘起される圧縮残留応力の効果で疲労強度の向上が実現される。
たとえば実際に、垂直構造物（Ａ）としてＪＩＳ：ＳＭ ５７０Ｑ鋼、水平附加構造物（Ｂ）としてこれと同じものを用い、溶接材料ＪＩＳ：ＹＧＷ２１を用いて溶接した場合のものに、この出願の発明によって、補強溶接部材として、その組成（ｗｔ％）が、Ｃ：０．０２５，Ｓｉ：０．３２，Ｍｕ：０．７０，Ｎｉ：１０．０，Ｃｒ：１０．０，Ｍｏ：０．１３，残部Ｆｅのものを用いて補強溶接を行った。
補強溶接では、溶接電圧２８Ｖ、溶接電流１８０〜２００Ａ、溶接速度５０〜６０ｃｍ／ｍｉｎであり、アルゴンガス８０％および炭酸ガス２０％のものをシールドガスとして２５ｌ／ｍｉｎで供給してのアーク溶接を行った。
この結果、補強溶接前の疲労限は４０ＭＰａであったものが、補強溶接後には８５ＭＰａとなった。
一方、前記の従来方法で行った場合には、割れが生じてしまった。
もちろん以上の例ではシールドガスを用いてのアーク溶接について説明したが、シールドガスを用いない被覆アーク溶接の場合にもこの出願の方法によってほぼ同様の効果が確認されている。
なお、以上の説明においては「上側」「下側」の表現がなされているが、これは溶接構造を図２および図４のように垂直構造物（Ａ）に対して水平附加構造物（Ｂ）が溶接されている場合と仮定しての規定である。
従って、この図２及び図４の構造が全体として回転して配置されている溶接構造や、さらには水平附加構造物（Ｂ）が直交せずに傾斜して溶接されている構造についても図２及び図４の配置のように考えることでこの出願の説明が適用されることは言うまでもない。
そして、この出願の説明において使用されている「低変態温度溶接材料」については、発明者により提案されている先行発明（特許第３０１０２１１号）に規定されたものである。
【発明の効果】
高い溶接強度を必要とする溶接構造物の補強溶接において、疲労強度が向上するとともに溶接割れの発生を防止した補強溶接方法が提供される。
【図面の簡単な説明】
【図１】この出願の発明による補強溶接経路を側面から見た模式図である。
【図２】この出願の発明による附加構造物を溶接した状態を示した断面図である。
【図３】従来法の補強溶接経路を側面から見た模式図である。
【図４】従来法の附加構造物を溶接した状態を示した断面図である。
【符号の説明】
Ａ 垂直構造物
Ｂ 水平附加構造物
１ 既溶接部材
２ 補強溶接部材
３ 補強溶接の溶接線
４ 附加構造物の下側
５ 附加構造物の下側端部
６ 附加構造物の側面
７ 附加構造物の上側端部
８ 附加構造物の上側
９ 溶接割れBACKGROUND OF THE INVENTION
The invention of this application relates to a reinforcement welding method for a welded structure that requires a high weld fatigue strength. More specifically, the invention of this application relates to a welding method for suppressing the occurrence of weld cracking in a reinforcing welding method using a low transformation temperature welding material.
[Prior art and its problems]
Conventionally, when welding structures or repairing, it has been inevitable that a tensile residual stress is induced in the weld due to heat shrinkage caused by cooling and the fatigue strength of the weld decreases.
In order to solve this problem, the inventor of this application uses a welding material whose martensitic transformation expansion ends at a temperature at or near the temperature at which welding is completed, a so-called low transformation temperature welding material and an inert shielding gas. "Welding methods" have been proposed, and these have already been patent-registered (Japanese Patent No. 3010211).
This new “welding method” significantly improved the fatigue strength of welded structures. However, when this low transformation temperature welding material is intended to improve fatigue strength by introducing compressive residual stress in the vicinity of the welded portion by reinforcement welding, it will be welded (Weld Crack) if it is repeatedly heated at a high temperature at the reinforcement site. May occur.
Conventional welding methods used welding materials that do not generate weld cracks even when repeatedly heated. Therefore, attention was paid to the shape of the welded part after welding, but most of the repeated heating of welding materials has not been achieved. Interest has not been paid.
Therefore, even when a low transformation temperature welding material is used to improve the welding fatigue strength, the method of repeatedly heating the welded member as in the conventional welding method may be employed as it is. Although the welding fatigue strength is expected to be improved by using the transformation temperature welding material, a situation occurs in which the effect cannot be sufficiently exhibited due to the occurrence of weld cracks in the welded portion.
Therefore, the invention of this application has been made in view of the above circumstances, and has been made by taking advantage of the characteristics of the low transformation temperature welding material proposed by the inventor and obtained an excellent effect in practice. It is an object of the present invention to provide a new reinforcing welding method capable of suppressing the occurrence of cracks and reliably improving the fatigue strength of the welded portion.
[Means for Solving the Problems]
The invention of this application is to solve the above problems. First, in a reinforcement welding method using a low transformation temperature welding material, while avoiding a thermal history due to the welding temperature in the low transformation temperature welding material. Provide a method of welding. Secondly, in a reinforcement welding method using a low transformation temperature welding material, a third method is to weld the lower side from the upper side of the end weld toe of the horizontal additional structure via the side surface. Provides a method of welding while moving the welding line so as to be linear, and fourth, a method characterized in that the welding method is arc welding using a low transformation temperature welding material. .
DETAILED DESCRIPTION OF THE INVENTION
The invention of this application has the features as described above, and an embodiment thereof will be described below. First and foremost, the invention of this application is to avoid a so-called high-temperature history that repeatedly heats the welding material in the reinforcing welding method using the low transformation temperature welding material.
For example, when a horizontal plate is welded to a vertical structure by a conventional welding method, welding is performed from the lower side of the horizontal plate to prevent melting and attach importance to the weld shape of the weld. The welding method has been adopted in which the welding line is raised to the left and right so that the railroad is switched back and welded up to the upper side of the plate-like body. Thus, in the conventional welding method, welding is performed such that the welding material is piled up sequentially from the lower side while swinging the welding line from side to side, so that the lower welding material once cooled is passed through the upper side. The heating was repeated. And when using the conventional welding material, there was no problem with such a welding method.
However, when a low transformation temperature welding material is used as the welding material, if such a welding method is applied as it is, the low transformation temperature welding material is likely to be repeatedly heated to cause weld cracking, and the original fatigue strength is improved. It may not be fully realized.
FIG. 3 and FIG. 4 show a mode when welding is performed by a conventional reinforcing welding method, although a low transformation temperature welding material is used for comparison with the invention of this application. FIG. 4 is a side view showing a state in which the additional structure (B) is welded to the vertical structure (A). (1) is an already welded member, and (2) is a reinforced welded member. FIG. 3 is a schematic diagram when viewed from the front left side of FIG. 4, and the periphery of the horizontally added structure (B) is welded by the already-welded member (1), and the periphery of the already-welded member (1) is It is covered with a reinforcing welding member (2) made of a low transformation temperature welding material.
And the conventional reinforcement welding method shown in FIG. 3 is a route that first welds the lower side (4) of the horizontally added structure (B) and then switches back the welding line (3) when the railway climbs a steep slope. Then, the side surface (6) is welded while moving from below to above and reaches the upper end (7), and then the upper side (8) is welded.
In this reinforcing welding method, in the process of ascending while moving the welding line (3) to the left and right, the lower welding member once cooled is repeatedly subjected to heat by the welding line (3) passing through the upper side, so that the reinforcing welding part is This was the cause of weld cracking (9).
Therefore, the invention of this application starts welding from the upper side of the welded portion of the plate-like body and welds while lowering the welding line so as to be linear, contrary to the conventional case, so as not to receive heat history as much as possible. Finally, the lower side is welded.
The reason why the welding is performed from the upper side to the lower side is that the low transformation temperature welding material uses the property that the viscosity is high and is not easily melted down, and this is easier to operate and the heat dissipation effect is better.
1 and 2 show a welding method according to the invention of this application. FIG. 1 is a schematic view seen from the left front of FIG. 2, and the periphery of the horizontally added structure (B) is welded by the already-welded member (1), and the periphery of the already-welded member (1) is low-transformed. It is covered with a reinforcing welding member (2) made of a temperature welding material. In the reinforcing welding method of the invention of this application, the upper side (8) of the horizontal appendage (B) is welded, as shown by the arrow of the welding line (3), as opposed to the conventional welding method shown in FIG. Then, welding is performed linearly downward along the side surface (6) of the appendage, and after the weld line (3) reaches the lower end (5) of the appendage, the lower side (4) is reinforcement welded.
In other words, the welding method of this application is a method in which welding is started from the lower side as in the conventional welding method, and the welding line is moved up and down while swinging to the left and right like a railroad switchback, and the welding materials are sequentially stacked. In addition, since welding is performed in a straight line from the top to the bottom, there is no thermal history for the low transformation temperature welding material, and welding cracks can be prevented.
In addition, since a low transformation temperature welding material is used, the fatigue strength can be improved by the effect of compressive residual stress induced in the vicinity of the weld.
For example, when actually using JIS: SM 570Q steel as the vertical structure (A) and the same as the horizontal additional structure (B) and welding using the welding material JIS: YGW21, According to the invention, the composition (wt%) of the reinforcing welded member is C: 0.025, Si: 0.32, Mu: 0.70, Ni: 10.0, Cr: 10.0, Mo: 0.00. 13, Reinforcement welding was performed using the remaining Fe.
In reinforcement welding, arc welding is performed with a welding voltage of 28 V, a welding current of 180 to 200 A, a welding speed of 50 to 60 cm / min, and an argon gas of 80% and carbon dioxide gas of 20% supplied as a shielding gas at 25 l / min. went.
As a result, the fatigue limit before reinforcement welding was 40 MPa, but after reinforcement welding was 85 MPa.
On the other hand, when the conventional method was used, cracking occurred.
Of course, in the above example, the arc welding using the shielding gas has been described. However, in the case of the covered arc welding not using the shielding gas, almost the same effect is confirmed by the method of this application.
In the above description, “upper side” and “lower side” are expressed, but this means that the welded structure is horizontally added to the vertical structure (A) as shown in FIGS. ) Is a presumption that it is welded.
Therefore, the welded structure in which the structure of FIGS. 2 and 4 is rotated as a whole, and the structure in which the horizontally added structure (B) is welded at an angle without being orthogonal are also shown in FIG. It goes without saying that the description of this application is applied by considering the arrangement as shown in FIG.
The “low transformation temperature welding material” used in the description of this application is specified in the prior invention (Japanese Patent No. 3010211) proposed by the inventors.
【The invention's effect】
In the reinforcement welding of a welded structure that requires high welding strength, there is provided a reinforcement welding method that improves fatigue strength and prevents occurrence of weld cracks.
[Brief description of the drawings]
FIG. 1 is a schematic view of a reinforcing welding path according to the invention of this application as viewed from the side.
FIG. 2 is a cross-sectional view showing a state where an additional structure according to the invention of this application is welded.
FIG. 3 is a schematic view of a conventional reinforcing welding path as seen from the side.
FIG. 4 is a cross-sectional view showing a state where a conventional additional structure is welded.
[Explanation of symbols]
A Vertical structure B Horizontal
Claims (4)
Priority Applications (8)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2002262236A JP3787622B2 (en) | 2002-09-09 | 2002-09-09 | Reinforcement welding method to suppress weld cracking |
| PCT/JP2003/011513 WO2004026519A1 (en) | 2002-09-09 | 2003-09-09 | Welding method using welding material of low transformation temperature |
| CNB038213524A CN100418689C (en) | 2002-09-09 | 2003-09-09 | Welding method using low transformation temperature welding material |
| EP03797566A EP1550526A4 (en) | 2002-09-09 | 2003-09-09 | WELDING PROCESS USING WELDING MATERIAL HAVING LOW TEMPERATURE OF PROCESSING |
| KR1020057004014A KR100659030B1 (en) | 2002-09-09 | 2003-09-09 | Welding method using welding material of low transformation temperature |
| US10/527,219 US20050252888A1 (en) | 2002-09-09 | 2003-09-09 | Welding method using welding material of low transformation temperature |
| US11/727,104 US20070181538A1 (en) | 2002-09-09 | 2007-03-23 | Welding method using welding material having low transformation temperature |
| US12/636,241 US20100089877A1 (en) | 2002-09-09 | 2009-12-11 | Welding method using welding material having low transformation temperature |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2002262236A JP3787622B2 (en) | 2002-09-09 | 2002-09-09 | Reinforcement welding method to suppress weld cracking |
Publications (2)
| Publication Number | Publication Date |
|---|---|
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| JP3787622B2 true JP3787622B2 (en) | 2006-06-21 |
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| JP5450293B2 (en) | 2010-07-01 | 2014-03-26 | 株式会社神戸製鋼所 | Fillet welded joint and gas shielded arc welding method |
| JP5751797B2 (en) * | 2010-10-21 | 2015-07-22 | ダイハツ工業株式会社 | Exhaust pipe welded structure |
| JP6005367B2 (en) * | 2011-06-22 | 2016-10-12 | デルタ工業株式会社 | Method for reinforcing plate structure using weld bead |
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