JP2014193483A - Electroslag welding method capable of obtaining weld metal excellent in toughness - Google Patents

Electroslag welding method capable of obtaining weld metal excellent in toughness Download PDF

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JP2014193483A
JP2014193483A JP2014027314A JP2014027314A JP2014193483A JP 2014193483 A JP2014193483 A JP 2014193483A JP 2014027314 A JP2014027314 A JP 2014027314A JP 2014027314 A JP2014027314 A JP 2014027314A JP 2014193483 A JP2014193483 A JP 2014193483A
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thin steel
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JP5943016B2 (en
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Hiroyuki Sumi
博幸 角
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JFE Steel Corp
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Abstract

PROBLEM TO BE SOLVED: To provide an electroslag welding method capable of improving the toughness of a weld metal and also of inhibiting variation of toughness when bonding a diaphragm to the inside of a box column composed of four skin plates by electroslag welding.SOLUTION: There is provided an electroslag welding method for bonding a diaphragm 2 to the inside of a box column composed of four skin plates 1. The electroslag welding is conducted by: providing a clearance between the upper face of the skin plate and the lower face of the diaphragm 2; contacting on the facing two sides of the diaphragm 2, the thin steel sheets, each of which contains 0.10 mass% or less of C, 0.008 mass% or less of N and has a thickness of 3 mm or less; contacting the lower faces of the thin steel sheets on the upper face of the skin plate 1; further, contacting a backing strips 3 on the thin steel sheets; and contacting the lower faces of the backing strips 3 on the upper face of the skin plate 1.

Description

本発明は、建築構造物の鉄骨として、４枚のスキンプレートで構成されるボックス柱の内側にダイアフラムを接合するためのエレクトロスラグ溶接方法に関するものである。   The present invention relates to an electroslag welding method for joining a diaphragm inside a box column composed of four skin plates as a steel frame of a building structure.

建築構造物の鉄骨として、４枚のスキンプレートで構成されるボックス柱の内側にダイアフラムを接合するにあたって、立向溶接を容易に行なうことができ、しかも大入熱の１パス溶接が可能な高能率溶接技術としてエレクトロスラグ溶接が用いられている。
このようなボックス柱に対して、近年、地震による塑性変形を防止して耐震性を高めるために、溶接金属の靭性を向上し、かつそのばらつきを抑制して、高い靭性を長期間にわたって安定して維持する技術が求められている。 As a steel frame of a building structure, when joining a diaphragm to the inside of a box column composed of four skin plates, vertical welding can be easily performed, and high-heat input one-pass welding is possible. Electroslag welding is used as an efficient welding technique.
In recent years, in order to prevent plastic deformation caused by earthquakes and improve earthquake resistance, the toughness of weld metal has been improved, and the variation has been suppressed to stabilize high toughness over a long period of time. Technology is needed.

しかしながらエレクトロスラグ溶接は、他のアーク溶接と比べて、溶接入熱が非常に大きいので、溶接金属の冷却速度の低下を招き、溶接金属の組織が粗大化しやすい。その結果、溶接金属の靭性が低下する傾向にある。そこで、エレクトロスラグ溶接によって形成される溶接金属の靭性を向上する技術が検討されている。
たとえば、溶接金属に微量のTiとBを添加させることによって、溶接金属の組織を微細化し、溶接金属の靭性を向上する手法が知られている。ところがエレクトロスラグ溶接は、スキンプレートやダイアフラム等の鋼材の溶融量が大きいので、TiとBが多量の溶融金属によって希釈されて、その効果が得られなくなる。つまり鋼材の成分は、溶接後の冷却過程で形成される溶接金属の組成に多大な影響を及ぼし、ひいては溶接金属の組織にも影響を及ぼす。 However, since electroslag welding has a much higher heat input than other arc weldings, the cooling rate of the weld metal is reduced, and the structure of the weld metal tends to be coarse. As a result, the toughness of the weld metal tends to decrease. Then, the technique which improves the toughness of the weld metal formed by electroslag welding is examined.
For example, a technique is known in which a minute amount of Ti and B are added to a weld metal to refine the structure of the weld metal and improve the toughness of the weld metal. However, in electroslag welding, since the amount of melting of steel materials such as skin plates and diaphragms is large, Ti and B are diluted with a large amount of molten metal, and the effect cannot be obtained. That is, the components of the steel material have a great influence on the composition of the weld metal formed in the cooling process after welding, and consequently the structure of the weld metal.

特にスキンプレートやダイアフラムのC含有量が0.1質量％を超える場合は、溶接金属に混入するC量が増加し、その結果、溶接金属の靭性が劣化するという問題がある。
またエレクトロスラグ溶接は、溶接線方向の溶融量が変動しやすいので、靭性のばらつきが大きくなる。つまりシャルピー衝撃試験で吸収エネルギーを測定して、靭性を評価する際に、試験片を採取する位置によっては、十分な吸収エネルギーの測定結果が得られないという問題が生じる。 In particular, when the C content of the skin plate or diaphragm exceeds 0.1% by mass, there is a problem that the amount of C mixed into the weld metal increases, and as a result, the toughness of the weld metal deteriorates.
In electroslag welding, the amount of melting in the weld line direction is likely to fluctuate, resulting in a large variation in toughness. That is, when the absorbed energy is measured by the Charpy impact test and the toughness is evaluated, there arises a problem that a sufficient absorption energy measurement result cannot be obtained depending on the position where the test piece is collected.

そこで、エレクトロスラグ溶接によって形成される溶接金属の靭性を向上するとともに、そのばらつきを抑制する技術が開発されている。
たとえば特許文献１に、δフェライト相を安定させ、かつ焼入れ性が向上する元素であるSi、Mo、Cr、NbおよびVを所定量含有するとともに、オーステナイト粒界における粗大な初析フェライトの生成を抑制する効果を有するBを所定量含有し、さらに、靭性を劣化する原因となるセメンタイト（Fe3C）が結晶粒内に生成するのを抑制するために、C含有量を低減した溶接ワイヤを用いて、大入熱のエレクトロスラグ溶接による溶接金属の靭性を安定して向上する技術が開示されている。 Therefore, a technique has been developed that improves the toughness of the weld metal formed by electroslag welding and suppresses the variation.
For example, Patent Document 1 discloses that a predetermined amount of Si, Mo, Cr, Nb and V, which are elements that stabilize the δ ferrite phase and improve the hardenability, is contained, and that coarse proeutectoid ferrite is generated at the austenite grain boundaries. In order to suppress the formation of cementite (Fe 3 C), which has a predetermined amount of B, which has an inhibitory effect, and further causes cementite (Fe 3 C) to deteriorate toughness, a welding wire with a reduced C content is used. And a technique for stably improving the toughness of the weld metal by electroslag welding with high heat input.

しかしこの技術では、溶接金属の酸素量に大きく影響するフラックスの成分について何ら考慮されておらず、溶接線方向に安定した靭性を得ることは困難である。
特許文献２には、溶接用ワイヤから多量のTiを添加するとともに、低塩基度のフラックスを用いて、アシキュラーフェライトの生成核となるTiを含む酸化物を溶融メタル中に分散させることによって、溶接金属をアシキュラーフェライト主体の組織として、靭性を安定して向上する技術が開示されている。 However, in this technique, no consideration is given to the flux component that greatly affects the oxygen content of the weld metal, and it is difficult to obtain stable toughness in the weld line direction.
In Patent Document 2, a large amount of Ti is added from a welding wire, and a low basicity flux is used to disperse an oxide containing Ti that is a nucleus of acicular ferrite in a molten metal. A technique for stably improving toughness using a weld metal as a structure mainly composed of acicular ferrite is disclosed.

しかしこの技術では、フラックスの成分としてB2O3を規定していないので、溶接線方向のB量の変動を抑えることができず、溶接線方向に安定した靭性を得ることは困難である。
特許文献３には、溶接用ワイヤ、鋼材、裏当金の成分を適正範囲に保持した上で、各々のN含有量の差を0.003質量％以内に調整することによって、溶接金属のミクロ組織の変動を抑制して、靭性を安定して向上する技術が開示されている。 However, in this technique, since B 2 O 3 is not defined as a flux component, fluctuations in the B amount in the weld line direction cannot be suppressed, and it is difficult to obtain stable toughness in the weld line direction.
In Patent Document 3, the components of the welding wire, steel, and backing metal are kept within an appropriate range, and the difference in N content is adjusted to within 0.003% by mass, thereby reducing the microstructure of the weld metal. Techniques for suppressing fluctuations and improving toughness stably are disclosed.

しかしこの技術では、溶接施工の現場において、使用する溶接用ワイヤと裏当金を、その成分に応じて、鋼材との組み合わせが最適になるように選別しなければならず、作業効率が低下するばかりでなく、溶接用ワイヤや裏当金の在庫管理の負荷が増大する。   However, with this technology, the welding wire and backing metal to be used must be selected so that the combination with the steel material is optimal in accordance with the components at the site of welding construction, and work efficiency is reduced. In addition, the burden of inventory management of welding wires and backing metal increases.

特開2002-79396号公報JP 2002-79396 JP 特開2004-114053号公報Japanese Patent Laid-Open No. 2004-114053 特開2005-305471号公報JP 2005-305471 A

本発明は、従来の技術の問題点を解消し、４枚のスキンプレートで構成されるボックス柱の内側にダイアフラムをエレクトロスラグ溶接で接合するにあって、溶接金属の靭性を向上し、かつ靭性のばらつきを抑制することができるエレクトロスラグ溶接方法を提供することを目的とする。   The present invention eliminates the problems of the prior art, improves the toughness of the weld metal and improves the toughness in joining the diaphragm to the inside of the box column composed of four skin plates by electroslag welding. It is an object of the present invention to provide an electroslag welding method capable of suppressing variations in the thickness.

本発明者は、ボックス柱を構成するスキンプレートとダイアフラムのエレクトロスラグ溶接において、溶接金属の高靭性化および安定化を図る技術について鋭意検討した。その結果、エレクトロスラグ溶接ではスキンプレートの溶融量が大きいので、C含有量が高いスキンプレートを用いた場合に、溶接用ワイヤやフラックスの成分と塩基度のバランスを最適に調整しても、溶接金属のC含有量が増加して、良好な靭性を確保することが困難であることが判明した。   The present inventors diligently studied a technique for increasing the toughness and stabilization of the weld metal in electroslag welding of the skin plate and the diaphragm constituting the box column. As a result, in electroslag welding, the melting amount of the skin plate is large, so when a skin plate with a high C content is used, the welding wire and flux components and the basicity balance can be adjusted optimally. It has been found that it is difficult to ensure good toughness by increasing the C content of the metal.

しかしながら建築構造物として十分な強度を確保するためには、C含有量の高いスキンプレートを使用せざるを得ないので、その溶接金属の靭性を向上する技術を開発する必要がある。
そこで、C含有量が高いスキンプレートを用いてエレクトロスラグ溶接を行なった場合の、溶接金属中のCを低減する技術について、さらに詳細に研究した。その結果、図１に示すように、ダイアフラムと裏当金との間に、C含有量が小さく、かつ所定の板厚を有する薄鋼板を挟み、かつ互いに当接させることによって開先を形成して、溶接を行なうことによって、溶接金属のC含有量の増加を抑えることが可能となり、ひいては溶接金属の溶接金属の高靭性化と、その靭性の安定化（ばらつきの抑制）を両立できることが分かった。 However, in order to ensure sufficient strength as a building structure, a skin plate with a high C content must be used, so it is necessary to develop a technique for improving the toughness of the weld metal.
Therefore, the technology for reducing C in the weld metal when electroslag welding was performed using a skin plate with a high C content was studied in more detail. As a result, as shown in FIG. 1, a groove is formed by sandwiching a thin steel plate having a small C content and a predetermined thickness between the diaphragm and the backing metal and bringing them into contact with each other. As a result of welding, it is possible to suppress an increase in the C content of the weld metal, which in turn can achieve both high weld metal toughness and stable toughness (suppression of variation). It was.

本発明は、このような知見に基づいてなされたものである。
すなわち本発明は、４枚のスキンプレートで構成されるボックス柱の内側にダイアフラムを接合するエレクトロスラグ溶接方法において、スキンプレートの上面とダイアフラムの下面との間に隙間を設け、ダイアフラムの対向する２つの側面にC：0.10質量％以下、N：0.008質量％以下を含有しかつ板厚３mm以下の薄鋼板を当接し、かつ薄鋼板の下面をスキンプレートの上面に当接し、さらにその薄鋼板の外面に裏当金を当接し、かつ裏当金の下面をスキンプレートの上面に当接して溶接を行なうエレクトロスラグ溶接方法である。 The present invention has been made based on such knowledge.
That is, according to the present invention, in an electroslag welding method for joining a diaphragm to the inside of a box column composed of four skin plates, a gap is provided between the upper surface of the skin plate and the lower surface of the diaphragm so that the diaphragms face each other. A thin steel plate containing C: 0.10 mass% or less, N: 0.008 mass% or less and having a thickness of 3 mm or less is brought into contact with one side surface, and the lower surface of the thin steel plate is brought into contact with the upper surface of the skin plate. This is an electroslag welding method in which a backing metal is brought into contact with the outer surface and welding is performed with the lower surface of the backing metal in contact with the upper surface of the skin plate.

ここで、スキンプレートの上面は、４枚のスキンプレートで構成されるボックス柱の内側表面を意味する。ダイアフラム、薄鋼板、裏当金の下面は、それぞれスキンプレートの上面に対向する面を意味する。
本発明のエレクトロスラグ溶接方法においては、薄鋼板を裏当金の内面に貼り付けることが好ましい。また、C：0.10〜0.20質量％、N：0.001〜0.01質量％を含有するスキンプレートを使用することが好ましい。さらには、薄鋼板とスキンプレートが、上記の組成に加えて、P：0.015質量％以下、S：0.005質量％以下を含有することが好ましい。 Here, the upper surface of the skin plate means the inner surface of the box column composed of four skin plates. The lower surfaces of the diaphragm, the thin steel plate, and the backing metal each mean a surface facing the upper surface of the skin plate.
In the electroslag welding method of the present invention, it is preferable to attach a thin steel plate to the inner surface of the backing metal. Moreover, it is preferable to use the skin plate containing C: 0.10-0.20 mass% and N: 0.001-0.01 mass%. Furthermore, it is preferable that the thin steel plate and the skin plate contain P: 0.015 mass% or less and S: 0.005 mass% or less in addition to the above composition.

本発明によれば、４枚のスキンプレートで構成されるボックス柱の内側にダイアフラムをエレクトロスラグ溶接で接合するにあって、エレクトロスラグ溶接による溶接金属の靭性を向上し、かつ靭性のばらつきを抑制することが可能となり、産業上格段の効果を奏する。   According to the present invention, when a diaphragm is joined to the inside of a box column composed of four skin plates by electroslag welding, the toughness of the weld metal by electroslag welding is improved and the variation in toughness is suppressed. It is possible to do so, and there is a remarkable effect in the industry.

本発明におけるスキンプレート、ダイアフラム、裏当金、薄鋼板の配置の例を模式的に示す断面図である。It is sectional drawing which shows typically the example of arrangement | positioning of the skin plate in this invention, a diaphragm, a backing metal, and a thin steel plate. ２mmＶノッチシャルピー衝撃試験片の採取位置を示す断面図である。It is sectional drawing which shows the collection position of a 2 mmV notch Charpy impact test piece.

図１は、本発明のエレクトロスラグ溶接方法におけるスキンプレート、ダイアフラム、裏当金、薄鋼板の配置の例を模式的に示す断面図である。以下に、図１を参照して本発明のエレクトロスラグ溶接方法について説明する。なお図１には、ボックス柱を構成する４枚のスキンプレートのうちの１枚のみを示す。
本発明を適用してエレクトロスラグ溶接を行なうにあたって、スキンプレート１、ダイアフラム２、裏当金３、薄鋼板４を組み合わせて開先を形成する。その開先においては、図１に示すように、スキンプレート１の上面とダイアフラム２の下面との間に隙間を設け、その隙間の高さをＬ（mm）する。そして、ダイアフラム２の対向する２面に薄鋼板４を当接させ、かつ薄鋼板４の下面をスキンプレート１の上面に当接させる。さらに、薄鋼板４の外面に裏当金３を当接させ、かつ裏当金３の下面をスキンプレート１の上面に当接させる。このようにして組み合わせたダイアフラム２の下面と、薄鋼板４の内面と、スキンプレート１の上面とによって形成される空間が、本発明における開先となる。 FIG. 1 is a cross-sectional view schematically showing an example of the arrangement of skin plates, diaphragms, backing metal, and thin steel plates in the electroslag welding method of the present invention. Below, the electroslag welding method of this invention is demonstrated with reference to FIG. FIG. 1 shows only one of the four skin plates constituting the box pillar.
In performing electroslag welding by applying the present invention, a groove is formed by combining the skin plate 1, the diaphragm 2, the backing metal 3, and the thin steel plate 4. At the groove, as shown in FIG. 1, a gap is provided between the upper surface of the skin plate 1 and the lower surface of the diaphragm 2, and the height of the gap is set to L (mm). Then, the thin steel plate 4 is brought into contact with two opposing surfaces of the diaphragm 2, and the lower surface of the thin steel plate 4 is brought into contact with the upper surface of the skin plate 1. Further, the backing metal 3 is brought into contact with the outer surface of the thin steel plate 4, and the lower surface of the backing metal 3 is brought into contact with the upper surface of the skin plate 1. The space formed by the lower surface of the diaphragm 2 combined in this way, the inner surface of the thin steel plate 4, and the upper surface of the skin plate 1 is a groove in the present invention.

ここで、スキンプレートの上面は、４枚のスキンプレートで構成されるボックス柱の内側表面を意味する。ダイアフラム、薄鋼板、裏当金の下面は、それぞれスキンプレートの上面に対向する面を意味する。
ダイアフラム２の下面とスキンプレート１の上面との距離Ｌ（mm）が20mm未満では、開先が狭すぎるので、エレクトロスラグ溶接が困難になる。一方、30mmを超えると、開先が広すぎるので、溶接施工の所要時間が長くなる。したがって距離Ｌは20〜30mmの範囲内が好ましい。 Here, the upper surface of the skin plate means the inner surface of the box column composed of four skin plates. The lower surfaces of the diaphragm, the thin steel plate, and the backing metal each mean a surface facing the upper surface of the skin plate.
If the distance L (mm) between the lower surface of the diaphragm 2 and the upper surface of the skin plate 1 is less than 20 mm, the groove is too narrow, and electroslag welding becomes difficult. On the other hand, if it exceeds 30 mm, the groove is too wide, so that the time required for welding is increased. Therefore, the distance L is preferably within a range of 20 to 30 mm.

なお、図１中のＤはダイアフラム２の板厚（mm）を指し、Ｔはスキンプレート１の板厚（mm）を指す。
ダイアフラム２の外面に薄鋼板４を当接させる手段は、溶接施工中にダイアフラム２と薄鋼板４の配置が変動しない手段を用いれば良く、特に限定しない。
薄鋼板４は、C：0.10質量％以下、N：0.008質量％以下を含有するものを使用する。さらには、P：0.015質量％以下、S：0.005質量％以下であることが好ましい。 In FIG. 1, D indicates the thickness (mm) of the diaphragm 2, and T indicates the thickness (mm) of the skin plate 1.
The means for bringing the thin steel plate 4 into contact with the outer surface of the diaphragm 2 is not particularly limited as long as the arrangement of the diaphragm 2 and the thin steel plate 4 does not change during welding.
As the thin steel plate 4, one containing C: 0.10% by mass or less and N: 0.008% by mass or less is used. Furthermore, it is preferable that P: 0.015 mass% or less, S: 0.005 mass% or less.

C含有量が0.10質量％を超える薄鋼板４を用いた場合は、溶接金属中のC量を低減することができないので、溶接金属の靭性改善効果が得られない。したがって薄鋼板４のC含有量は0.10質量％を上限とする。
N含有量が0.008質量％を超える薄鋼板４を用いた場合は、溶接金属中のN量が増加し、その結果、溶接金属の靭性に悪影響を及ぼす固溶N量も増加する。溶接金属の靭性を向上し、かつ靭性のばらつきを抑制するためには、薄鋼板４のN含有量を低く抑えることによって、溶接金属に完全希釈されるN量を低減する必要がある。したがって薄鋼板４のN含有量は0.008質量％を上限とする。 When the thin steel plate 4 having a C content exceeding 0.10% by mass is used, the C content in the weld metal cannot be reduced, so that the effect of improving the toughness of the weld metal cannot be obtained. Therefore, the upper limit of the C content of the thin steel plate 4 is 0.10% by mass.
When the thin steel plate 4 having an N content exceeding 0.008% by mass is used, the amount of N in the weld metal increases, and as a result, the amount of solute N that adversely affects the toughness of the weld metal also increases. In order to improve the toughness of the weld metal and suppress the variation in toughness, it is necessary to reduce the amount of N completely diluted in the weld metal by keeping the N content of the thin steel plate 4 low. Therefore, the upper limit of the N content of the thin steel plate 4 is 0.008% by mass.

P含有量が0.015質量％を超える薄鋼板４を用いた場合は、溶接金属中のP量が増加し、その結果、溶接金属の靭性が劣化する。したがって薄鋼板４のP含有量は0.015質量％以下が好ましい。
S含有量が0.005質量％を超える薄鋼板４を用いた場合は、溶接金属中のS量が増加し、その結果、溶接金属の靭性が劣化する。したがって薄鋼板４のS含有量は0.005質量％以下が好ましい。 When the thin steel plate 4 having a P content exceeding 0.015% by mass is used, the amount of P in the weld metal increases, and as a result, the toughness of the weld metal deteriorates. Therefore, the P content of the thin steel plate 4 is preferably 0.015% by mass or less.
When the thin steel plate 4 having an S content exceeding 0.005 mass% is used, the amount of S in the weld metal increases, and as a result, the toughness of the weld metal deteriorates. Therefore, the S content of the thin steel plate 4 is preferably 0.005% by mass or less.

また、薄鋼板４の板厚が３mmを超えると、裏当金３を十分に溶融できず、融合不良による溶接欠陥が発生し易くなる。したがって薄鋼板４の板厚は３mm以下とする。好ましくは１〜２mmである。
裏当金３の内面に薄鋼板４を当接させる手段は、溶接施工中に裏当金３と薄鋼板４の配置が変動しない手段を用いれば良く、特に限定しない。 On the other hand, if the thickness of the thin steel plate 4 exceeds 3 mm, the backing metal 3 cannot be sufficiently melted, and a welding defect due to poor fusion tends to occur. Therefore, the thickness of the thin steel plate 4 is 3 mm or less. Preferably it is 1-2 mm.
The means for bringing the thin steel plate 4 into contact with the inner surface of the backing metal 3 may be any means that does not change the arrangement of the backing metal 3 and the thin steel plate 4 during welding, and is not particularly limited.

スキンプレート１は、C：0.10〜0.20質量％、N：0.001〜0.01質量％を含有するものを使用することが好ましい。さらには、P：0.015質量％以下、S：0.005質量％以下であることが好ましい。
C含有量が0.10質量％未満のスキンプレート１を用いた場合は、溶接金属中のC量が不足して、十分な強度を有する溶接金属が得られない。一方、C含有量が0.20質量％を超えると、溶接金属中のC量が増加して、溶接金属の靭性が劣化するばかりでなく、エレクトロスラグ溶接による溶接熱影響部の靭性も劣化する。したがってスキンプレート１のC含有量は0.10〜0.20質量％の範囲内が好ましい。 It is preferable to use the skin plate 1 containing C: 0.10 to 0.20% by mass and N: 0.001 to 0.01% by mass. Furthermore, it is preferable that P: 0.015 mass% or less, S: 0.005 mass% or less.
When the skin plate 1 having a C content of less than 0.10% by mass is used, the amount of C in the weld metal is insufficient and a weld metal having sufficient strength cannot be obtained. On the other hand, when the C content exceeds 0.20% by mass, not only the amount of C in the weld metal increases and the toughness of the weld metal deteriorates, but also the toughness of the heat affected zone due to electroslag welding deteriorates. Therefore, the C content of the skin plate 1 is preferably in the range of 0.10 to 0.20 mass%.

NはAlやTiと結合することによって、溶接金属のオーステナイト結晶粒を微細化するとともに、溶接熱影響部の靭性も向上する作用を有するので、靭性の向上とそのばらつきの抑制を図ることができる。N含有量が0.001質量％未満のスキンプレート１を用いた場合は、このような効果が得られない。一方、N含有量が0.01質量％を超えると、溶接金属中に希釈されるN量が増加して、溶接金属の靭性が劣化するばかりでなく、溶接熱影響部に固溶するN量も増加して、溶接熱影響部の靭性が劣化する。したがってスキンプレート１のN含有量は0.001〜0.01質量％の範囲内が好ましい。   N combines with Al and Ti to refine the austenite crystal grains of the weld metal and to improve the toughness of the weld heat affected zone, so that it is possible to improve toughness and suppress variations. . When the skin plate 1 having an N content of less than 0.001% by mass is used, such an effect cannot be obtained. On the other hand, if the N content exceeds 0.01% by mass, the amount of N diluted in the weld metal increases, and the toughness of the weld metal deteriorates, and the amount of N dissolved in the weld heat affected zone also increases. As a result, the toughness of the weld heat affected zone deteriorates. Therefore, the N content of the skin plate 1 is preferably in the range of 0.001 to 0.01% by mass.

Pは、溶接金属においては不可避的不純物元素であり、粒界に偏析することで粒界脆化が生じて、靭性が劣化する。そのため、溶接金属のP量は低いほど好ましく、スキンプレート１のP含有量は0.015質量％以下が好ましい。
SもPと同様に、溶接金属においては不可避的不純物元素であり、粒界脆化や介在物の増加により靭性が劣化する。そのため、溶接金属のS量は低いほど好ましく、スキンプレート１のS含有量は0.005質量％以下が好ましい。 P is an unavoidable impurity element in the weld metal, and segregates at the grain boundaries to cause grain boundary embrittlement and deteriorate toughness. Therefore, the lower the P content of the weld metal, the better. The P content of the skin plate 1 is preferably 0.015% by mass or less.
S, like P, is an inevitable impurity element in weld metal, and its toughness deteriorates due to grain boundary embrittlement and increased inclusions. Therefore, the lower the S content of the weld metal, the better. The S content of the skin plate 1 is preferably 0.005% by mass or less.

本発明によれば、以上で説明したようにスキンプレート１、ダイアフラム２、裏当金３、薄鋼板４を組み合わせて、ダイアフラム２の下面と、薄鋼板４の内面と、スキンプレート１の上面とによって形成される空間を開先として、その開先に溶接ワイヤを挿入し、かつ溶接ワイヤをその長手方向に前後進（いわゆるオシレート）させながら、エレクトロスラグ溶接を行なうことによって、溶接金属の靭性を向上し、かつ靭性のばらつきを抑制することができる。   According to the present invention, as described above, the skin plate 1, the diaphragm 2, the backing metal 3, and the thin steel plate 4 are combined, and the lower surface of the diaphragm 2, the inner surface of the thin steel plate 4, and the upper surface of the skin plate 1 The toughness of the weld metal is reduced by performing electroslag welding while inserting a welding wire into the groove and moving the welding wire back and forth in the longitudinal direction (so-called oscillate). It is possible to improve and suppress variation in toughness.

図１に示すように、スキンプレート１、ダイアフラム２、裏当金３、薄鋼板４を組み合わせて、ダイアフラム２の下面と、薄鋼板４の内面と、スキンプレート１の上面とによって形成される空間を開先として、その開先に溶接ワイヤ（ワイヤ径1.6mm）を挿入して、オシレートさせながらエレクトロスラグ溶接を行なった。
スキンプレート１の板厚Ｔは40mmとし、ダイアフラム２（板厚Ｄ：40mm）の下面とスキンプレート１の上面との距離Ｌは25mmとした。裏当金３はＪＩＳ規格SN490に規定されるフラットバーを使用し、その内面に板厚１〜４mmの薄鋼板４を貼り付けた。 As shown in FIG. 1, a space formed by a lower surface of the diaphragm 2, an inner surface of the thin steel plate 4, and an upper surface of the skin plate 1 by combining the skin plate 1, the diaphragm 2, the backing metal 3, and the thin steel plate 4. As a groove, a welding wire (wire diameter 1.6 mm) was inserted into the groove, and electroslag welding was performed while oscillating.
The plate thickness T of the skin plate 1 was 40 mm, and the distance L between the lower surface of the diaphragm 2 (plate thickness D: 40 mm) and the upper surface of the skin plate 1 was 25 mm. As the backing metal 3, a flat bar defined in JIS standard SN490 was used, and a thin steel plate 4 having a thickness of 1 to 4 mm was attached to the inner surface thereof.

スキンプレート１の成分は表１に示す通りである。またダイアフラム２は、表１に示すスキンプレート１と同じ成分のものを組み合わせて使用した。薄鋼板４の成分は表２に示す通りである。
エレクトロスラグ溶接の設定条件は表３に示す通りである。 The components of the skin plate 1 are as shown in Table 1. Diaphragm 2 was used in combination with the same components as skin plate 1 shown in Table 1. The components of the thin steel plate 4 are as shown in Table 2.
Table 3 shows the setting conditions for electroslag welding.

Figure 2014193483
Figure 2014193483

Figure 2014193483
Figure 2014193483

Figure 2014193483
Figure 2014193483

溶接が終了した後、超音波探傷試験によって溶接金属５の探傷を行ない、溶接欠陥が認められない部位から２mmＶノッチシャルピー衝撃試験片６（以下、試験片という）を３個ずつ採取した。試験片６を採取した位置は、断面図として図２に示す通りであり、溶接金属５内にノッチを設けるように試験片６を切り出した。
次いで、試験片６を用いてシャルピー衝撃試験（試験温度０℃）を行ない、吸収エネルギVＥ0（Ｊ）を測定した。その結果を表４に示す。なお表４中のVＥ0値は、それぞれ３回ずつ測定した結果の平均値である。 After the welding was completed, the weld metal 5 was flawed by an ultrasonic flaw detection test, and three 2 mm V notch Charpy impact test pieces 6 (hereinafter referred to as “test pieces”) were sampled from portions where no welding flaw was observed. The position where the test piece 6 was collected is as shown in FIG. 2 as a cross-sectional view, and the test piece 6 was cut out so as to provide a notch in the weld metal 5.
Then, subjected to Charpy impact test (test temperature 0 ° C.) using a specimen 6 was measured absorbed energy V E 0 (J). The results are shown in Table 4. The V E 0 values in Table 4 are average values of the results obtained by measuring three times each.

Figure 2014193483
Figure 2014193483

表４から明らかなように、発明例（溶接継手ａ、ｂ、ｄ〜ｇ）では、吸収エネルギVＥ0の平均値が85〜120Ｊと高くなっており、靭性に優れた溶接金属が得られた。
また発明例のVＥ0の測定値は、溶接継手ａが106〜122Ｊ、溶接継手ｂが115〜123Ｊ、溶接継手ｄが94〜101Ｊ、溶接継手ｅが102〜118Ｊ、溶接継手ｆが86〜97Ｊ、溶接継手ｇが82〜88Ｊの範囲内であり、ばらつきは小さく抑えられた。 As is apparent from Table 4, in the invention examples (welded joints a, b, d to g), the average value of the absorbed energy V E 0 is as high as 85 to 120 J, and a weld metal having excellent toughness can be obtained. It was.
In addition, the measured values of V E 0 of the invention example are as follows: welded joint a is 106 to 122 J, welded joint b is 115 to 123 J, welded joint d is 94 to 101 J, welded joint e is 102 to 118 J, and welded joint f is 86 to 97J and the welded joint g were in the range of 82 to 88J, and the variation was suppressed to be small.

比較例である溶接継手ｃは、薄鋼板４の板厚が本発明の範囲を超える例であり、融合不良が発生した。溶接継手ｈは薄鋼板４のC含有量が本発明の範囲を超える例、溶接継手ｉはスキンプレート１のC含有量が本発明の範囲を超える例、溶接継手ｊはスキンプレート１のN含有量が本発明の範囲を超える例であり、いずれも吸収エネルギVＥ0が小さくなり、溶接金属の靭性は発明例に比べて大幅に劣化した。 The welded joint c, which is a comparative example, is an example in which the thickness of the thin steel plate 4 exceeds the range of the present invention, and poor fusion occurred. The welded joint h is an example in which the C content of the thin steel plate 4 exceeds the range of the present invention, the welded joint i is an example in which the C content of the skin plate 1 exceeds the range of the present invention, and the welded joint j is an N content of the skin plate 1 In all cases, the amount exceeds the range of the present invention, the absorbed energy V E 0 is reduced, and the toughness of the weld metal is significantly deteriorated as compared with the inventive example.

また比較例のVＥ0の測定値は、溶接継手ｈが29〜62Ｊ、溶接継手ｉが15〜30Ｊ、溶接継手ｊが16〜31Ｊの範囲内であり、ばらつきは発明例に比べて大きくなった。
さらに、溶接継手ｋはスキンプレート１のP含有量が本発明の好ましい範囲を超える例、溶接継手ｌはスキンプレート１のS含有量が本発明の好ましい範囲を超える例、溶接継手ｍは薄鋼板４のS含有量が本発明の好ましい範囲を超える例、溶接継手ｎは薄鋼板４のP含有量が本発明の好ましい範囲を超える例である。いずれも吸収エネルギVＥ0が小さく、溶接金属の靭性は発明例に比べて大幅に劣化した。 The measured values of V E 0 in the comparative example are within the range of 29 to 62 J for the welded joint h, 15 to 30 J for the welded joint i, and 16 to 31 J for the welded joint j, and the variation is larger than that of the invention example. It was.
Furthermore, the welded joint k is an example in which the P content of the skin plate 1 exceeds the preferred range of the present invention, the welded joint l is an example in which the S content of the skin plate 1 exceeds the preferred range of the present invention, and the welded joint m is a thin steel plate. An example in which the S content of 4 exceeds the preferable range of the present invention, and the welded joint n is an example in which the P content of the thin steel plate 4 exceeds the preferable range of the present invention. In all cases, the absorbed energy V E 0 was small, and the toughness of the weld metal was significantly deteriorated as compared with the inventive examples.

これらの比較例のVＥ0の測定値は、溶接継手ｋが20〜25Ｊ、溶接継手ｌが16〜27Ｊ、溶接継手ｍが29〜43Ｊ、溶接継手ｎが26〜30Ｊの範囲内であり、ばらつきは発明例に比べて大きくなった。 The measured values of V E 0 of these comparative examples are in the range of 20 to 25 J for the welded joint k, 16 to 27 J for the welded joint l, 29 to 43 J for the welded joint m, and 26 to 30 J for the welded joint n. The variation was larger than that of the inventive example.

１ スキンプレート
２ ダイアフラム
３ 裏当金
４ 薄鋼板
５ 溶接金属
６ ２mmＶノッチシャルピー衝撃試験片 DESCRIPTION OF SYMBOLS 1 Skin plate 2 Diaphragm 3 Backing metal 4 Thin steel plate 5 Weld metal 6 2mmV notch Charpy impact test piece

Claims (5)

４枚のスキンプレートで構成されるボックス柱の内側にダイアフラムを接合するエレクトロスラグ溶接方法において、前記スキンプレートの上面と前記ダイアフラムの下面との間に隙間を設け、前記ダイアフラムの対向する２つの側面にC：0.10質量％以下、N：0.008質量％以下を含有しかつ板厚３mm以下の薄鋼板を当接し、かつ前記薄鋼板の下面を前記スキンプレートの上面に当接し、さらに前記薄鋼板の外面に裏当金を当接し、かつ該裏当金の下面を前記スキンプレートの上面に当接して溶接を行なうことを特徴とするエレクトロスラグ溶接方法。   In the electroslag welding method for joining a diaphragm to the inside of a box column constituted by four skin plates, a gap is provided between the upper surface of the skin plate and the lower surface of the diaphragm, and two opposing side surfaces of the diaphragm C: 0.10% by mass or less, N: 0.008% by mass or less, and a thin steel plate having a thickness of 3 mm or less is brought into contact, and the lower surface of the thin steel plate is brought into contact with the upper surface of the skin plate. An electroslag welding method, wherein welding is carried out by bringing a backing metal into contact with an outer surface and bringing the lower surface of the backing metal into contact with the upper surface of the skin plate. 前記薄鋼板を前記裏当金の内面に貼り付けることを特徴とする請求項１に記載のエレクトロスラグ溶接方法。   The electroslag welding method according to claim 1, wherein the thin steel plate is attached to an inner surface of the backing metal. 前記スキンプレートがC：0.10〜0.20質量％、N：0.001〜0.01質量％を含有することを特徴とする請求項１または２に記載のエレクトロスラグ溶接方法。   The electroslag welding method according to claim 1 or 2, wherein the skin plate contains C: 0.10 to 0.20 mass% and N: 0.001 to 0.01 mass%. 前記薄鋼板が、さらに、P：0.015質量％以下、S：0.005質量％以下を含有することを特徴とする請求項１〜３のいずれか一項に記載のエレクトロスラグ溶接方法。   The electroslag welding method according to any one of claims 1 to 3, wherein the thin steel sheet further contains P: 0.015 mass% or less and S: 0.005 mass% or less. 前記スキンプレートが、さらに、P：0.015質量％以下、S：0.005質量％以下を含有することを特徴とする請求項３または４に記載のエレクトロスラグ溶接方法。   The electroslag welding method according to claim 3 or 4, wherein the skin plate further contains P: 0.015 mass% or less and S: 0.005 mass% or less.
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Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS4853948A (en) * 1971-11-11 1973-07-28
JPS63252684A (en) * 1987-04-10 1988-10-19 Toshiba Corp Manufacture of impeller for hydraulic machinery
JP2005305471A (en) * 2004-04-19 2005-11-04 Nippon Steel Corp Method of electroslag welding for giving excellent toughness to weld metal

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS4853948A (en) * 1971-11-11 1973-07-28
JPS63252684A (en) * 1987-04-10 1988-10-19 Toshiba Corp Manufacture of impeller for hydraulic machinery
JP2005305471A (en) * 2004-04-19 2005-11-04 Nippon Steel Corp Method of electroslag welding for giving excellent toughness to weld metal

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