JP4903107B2 - Welded joint - Google Patents
Welded joint Download PDFInfo
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- JP4903107B2 JP4903107B2 JP2007254421A JP2007254421A JP4903107B2 JP 4903107 B2 JP4903107 B2 JP 4903107B2 JP 2007254421 A JP2007254421 A JP 2007254421A JP 2007254421 A JP2007254421 A JP 2007254421A JP 4903107 B2 JP4903107 B2 JP 4903107B2
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- 239000002184 metal Substances 0.000 claims description 74
- 229910052751 metal Inorganic materials 0.000 claims description 74
- 229910000831 Steel Inorganic materials 0.000 claims description 24
- 239000010959 steel Substances 0.000 claims description 24
- 238000003466 welding Methods 0.000 claims description 24
- 239000000463 material Substances 0.000 claims description 21
- 239000000203 mixture Substances 0.000 claims description 12
- 239000000126 substance Substances 0.000 claims description 9
- 239000012535 impurity Substances 0.000 claims description 3
- 230000000694 effects Effects 0.000 description 14
- 230000000052 comparative effect Effects 0.000 description 9
- 238000007670 refining Methods 0.000 description 6
- 229910001566 austenite Inorganic materials 0.000 description 4
- 238000010790 dilution Methods 0.000 description 4
- 239000012895 dilution Substances 0.000 description 4
- 238000000034 method Methods 0.000 description 4
- 229910045601 alloy Inorganic materials 0.000 description 3
- 239000000956 alloy Substances 0.000 description 3
- 230000006866 deterioration Effects 0.000 description 3
- 230000000087 stabilizing effect Effects 0.000 description 3
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 2
- 238000010276 construction Methods 0.000 description 2
- 238000005336 cracking Methods 0.000 description 2
- 230000007423 decrease Effects 0.000 description 2
- 238000005259 measurement Methods 0.000 description 2
- 239000001301 oxygen Substances 0.000 description 2
- 229910052760 oxygen Inorganic materials 0.000 description 2
- 230000001105 regulatory effect Effects 0.000 description 2
- 238000007711 solidification Methods 0.000 description 2
- 230000008023 solidification Effects 0.000 description 2
- 230000002195 synergetic effect Effects 0.000 description 2
- 229910001563 bainite Inorganic materials 0.000 description 1
- 239000000446 fuel Substances 0.000 description 1
- 239000007789 gas Substances 0.000 description 1
- 238000009863 impact test Methods 0.000 description 1
- 229910000734 martensite Inorganic materials 0.000 description 1
- 229910052750 molybdenum Inorganic materials 0.000 description 1
- 229910052759 nickel Inorganic materials 0.000 description 1
- 229910052758 niobium Inorganic materials 0.000 description 1
- 238000007747 plating Methods 0.000 description 1
- 230000002250 progressing effect Effects 0.000 description 1
- 230000000171 quenching effect Effects 0.000 description 1
- 238000003860 storage Methods 0.000 description 1
- 238000009864 tensile test Methods 0.000 description 1
- 230000008719 thickening Effects 0.000 description 1
- 230000007704 transition Effects 0.000 description 1
- 229910052720 vanadium Inorganic materials 0.000 description 1
- 229910000859 α-Fe Inorganic materials 0.000 description 1
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- Arc Welding In General (AREA)
- Nonmetallic Welding Materials (AREA)
Description
本発明は、ＹＰ４６０鋼等の降伏強度が４６０Ｎ／ｍｍ２以上の鋼材をエレクトロガスアーク溶接法により溶接した溶接継手に関する。 The present invention relates to a welded joint in which a steel material having a yield strength of 460 N / mm 2 or more such as YP460 steel is welded by an electrogas arc welding method.
エレクトロガスアーク溶接は、高能率立向溶接方法として、船舶、石油貯蔵タンク及び橋梁等の幅広い分野に適用されている。近時、中国・東アジア諸国の経済、産業の発展が著しく、物流量の増加に伴い、コンテナ貨物の効率的な輸送を目的に、コンテナ船の大型化が急速に進んでいる。 Electrogas arc welding is applied to a wide range of fields such as ships, oil storage tanks and bridges as a highly efficient vertical welding method. In recent years, the economic and industrial development of China and East Asian countries has been remarkable, and with the increase of goods flow, the size of container ships has been increasing rapidly for the purpose of efficient transportation of container cargo.
コンテナ船の大型化に伴い、船側外板又はハッチコーミング等の厚肉化が進んでおり、コンテナ積載数が８０００ＴＥＵの場合、降伏強度が３９０Ｎ／ｍｍ２の鋼材を使用すると、適用板厚は８０ｍｍ程度となる。一方で、鋼材の降伏強度を４６０Ｎ／ｍｍ２以上とすることで、適用板厚は６０ｍｍ程度に薄くすることができ、船体の軽量化が可能である。これにより、燃費効率が向上するうえ、溶接施工能率も向上する。 Along with the increase in size of container ships, thickening of ship side shells or hatch coaming is progressing. When the number of containers loaded is 8000 TEU, when steel material with a yield strength of 390 N / mm 2 is used, the applicable plate thickness is 80 mm. It will be about. On the other hand, by setting the yield strength of the steel material to 460 N / mm 2 or more, the applicable plate thickness can be reduced to about 60 mm, and the weight of the hull can be reduced. As a result, fuel efficiency is improved and welding construction efficiency is also improved.
従来から、降伏強度が４６０Ｎ／ｍｍ２以上の鋼材に対するエレクトロガスアーク溶接の適用に関する検討がなされている。例えば、特許文献１はワイヤの化学組成及び溶接金属の化学組成を規定することにより、耐脆性破壊特性を向上させたエレクトロガスアーク溶接方法を提案している。 Conventionally, studies on the application of electrogas arc welding to steel materials having a yield strength of 460 N / mm 2 or more have been made. For example, Patent Document 1 proposes an electrogas arc welding method in which the brittle fracture resistance is improved by defining the chemical composition of the wire and the chemical composition of the weld metal.
しかし、このような高強度の鋼材を適用するためには、溶接継手強度の確保が重要であり、エレクトロガスアーク溶接のような大入熱溶接の場合には、鋼材の熱影響部の幅が大きいため、熱影響による鋼材の軟化幅も増大し、十分な継手強度が確保できないという問題点がある。 However, in order to apply such a high-strength steel material, it is important to ensure the strength of the welded joint. In the case of high heat input welding such as electrogas arc welding, the width of the heat-affected zone of the steel material is large. For this reason, there is a problem that the softening width of the steel material due to the heat effect increases, and sufficient joint strength cannot be secured.
そこで、このような課題の解決のため、溶接金属の強度を従来よりも高めて、熱影響部の塑性変形を拘束し、継手強度の確保を図ることが提案された。 Therefore, in order to solve such a problem, it has been proposed to increase the strength of the weld metal as compared with the prior art to restrain the plastic deformation of the heat-affected zone and secure the joint strength.
しかし、単純に、従来ワイヤより更に合金成分を添加して、溶接金属の強度を高めただけでは、衝撃性能が劣化してしまうという問題点がある。 However, simply adding an alloy component further than the conventional wire to increase the strength of the weld metal has a problem that the impact performance deteriorates.
本発明はかかる問題点に鑑みてなされたものであって、降伏強度が４６０Ｎ／ｍｍ２以上の鋼材のエレクトロガスアーク溶接において、継手強度及び衝撃性能がいずれも優れた溶接継手を提供することを目的とする。 The present invention has been made in view of such a problem, and an object of the present invention is to provide a welded joint having excellent joint strength and impact performance in electrogas arc welding of a steel material having a yield strength of 460 N / mm 2 or more. And
本発明に係る溶接継手は、降伏強度が４６０Ｎ／ｍｍ２以上の鋼材をエレクトロガスアーク溶接した溶接継手であって、
溶接金属の化学組成が、
Ｃ：０．０５乃至０．０７質量％
Ｓｉ：０．１０乃至０．３０質量％
Ｍｎ：１．４０乃至１．８０質量％
Ｎｉ：０．９乃至１．３質量％
Ｍｏ：０．４乃至０．６質量％
Ｔｉ：０．０３乃至０．０６質量％
Ｂ：０．００２乃至０．００６質量％
を含有し、
Ｐ：０．０２質量％以下
Ｓ：０．０２質量％以下
Ｃｕ：０．２質量％以下
Ｃｒ：０．０５質量％以下
Ａｌ：０．０２質量％以下
Ｏ：０．０４質量％以下
Ｎ：０．００７５質量％以下
に規制し、
残部がＦｅ及び不可避的不純物からなるものであり、
かつ溶接金属の硬さがビッカース硬度でＨｖ：２２０乃至２３５であることを特徴とする。
The welded joint according to the present invention is a welded joint obtained by electrogas arc welding of a steel material having a yield strength of 460 N / mm 2 or more,
The chemical composition of the weld metal
C: 0.05 to 0.07% by mass
Si: 0.10 to 0.30 mass%
Mn: 1.40 to 1.80 mass%
Ni: 0.9 to 1.3% by mass
Mo: 0.4 to 0.6% by mass
Ti: 0.03 to 0.06 mass%
B: 0.002 to 0.006 mass%
Containing
P: 0.02 mass% or less S: 0.02 mass% or less Cu: 0.2 mass% or less Cr: 0.05 mass% or less Al: 0.02 mass% or less O: 0.04 mass% or less N: Restricted to 0.0075 mass% or less,
The balance consists of Fe and inevitable impurities,
The weld metal has a Vickers hardness of Hv: 220 to 235.
本発明によれば、溶接金属の組成及び硬さを適切に規定することにより、継手強度が高く、かつ衝撃性能が優れた溶接継手を得ることができる。 According to the present invention, a weld joint having high joint strength and excellent impact performance can be obtained by appropriately defining the composition and hardness of the weld metal.
以下、本発明の実施の形態について、具体的に説明する。１電極エレクトロガスアーク溶接において、本発明者らが鋭意検討した結果、溶接金属の化学組成範囲を細かく適切に規定することと、溶接金属の硬さの範囲を規定することにより、溶接継手の強度及び衝撃性能を高めることができることを見出した。 Hereinafter, embodiments of the present invention will be specifically described. In the one-electrode electrogas arc welding, as a result of intensive studies by the present inventors, the chemical composition range of the weld metal is finely and appropriately defined, and the hardness range of the weld metal is defined, whereby the strength of the weld joint and It has been found that impact performance can be enhanced.
従来、被溶接鋼板の厚肉化に伴う溶接入熱の増大による溶接金属の強度低下及び靱性劣化に対して、主に、靱性を安定化させる効果があるＮｉの添加による改善を図ってきた。従って、板厚６０ｍｍのエレクトロガスアーク溶接金属は、Ｎｉを２質量％以上含有する場合も認められた。しかし、このようにＮｉが主体の成分系で継手強度を確保するために合金成分を添加して強度を高めると、靭性が劣化する傾向が認められた。 Conventionally, improvement in weld metal strength and toughness deterioration due to increased welding heat input accompanying the increase in the thickness of the welded steel sheet has been attempted mainly by addition of Ni, which has the effect of stabilizing toughness. Therefore, an electrogas arc weld metal having a plate thickness of 60 mm was recognized even when Ni contained 2% by mass or more. However, when the alloy component is added to increase the strength in order to ensure the joint strength in such a component system mainly composed of Ni, the tendency to deteriorate the toughness was recognized.
そこで、本発明者らは、合金成分量が少なくても、強度低下及び靭性劣化を防止できる成分系の溶接金属を開発すべく鋭意検討した結果、従来の溶接金属よりもＮｉ量を減らし、Ｍｏを添加することで、組織の微細化が可能となり、厚板における強度及び靭性の確保が可能となることを見出した。但し、Ｎｉを過度に減らすと、遷移温度を低下させる効果がなくなり、低温での靱性が劣化する。一方、Ｍｏ量が過大となると、焼入れ効果が高いため、強度が高くなり過ぎ、靱性が劣化する傾向となる。 Therefore, the present inventors have intensively studied to develop a component-based weld metal that can prevent strength reduction and toughness deterioration even when the alloy component amount is small. It has been found that the addition of can make the microstructure finer and ensure the strength and toughness of the thick plate. However, if Ni is excessively reduced, the effect of lowering the transition temperature is lost, and the toughness at low temperatures deteriorates. On the other hand, if the amount of Mo is excessive, the quenching effect is high, so the strength becomes too high and the toughness tends to deteriorate.
このように、溶接金属の強度を高めると靭性が劣化するため、強度を低くする方が望ましいが、エレクトロガスアーク溶接のような大入熱溶接の場合、鋼材の熱影響部が軟化し、溶接金属の強度を低くすると、継手強度の確保が難しくなる。 As described above, increasing the strength of the weld metal degrades the toughness, so lowering the strength is desirable. However, in the case of high heat input welding such as electrogas arc welding, the heat-affected zone of the steel material is softened and the weld metal is reduced. When the strength of the steel is lowered, it is difficult to ensure the strength of the joint.
そこで、本発明においては、溶接金属のビッカース硬さＨｖを２２０以上とすることにより、板厚が４０ｍｍ以上の鋼材のエレクトロガスアーク溶接においても、十分な継手強度を確保することを可能とした。 Therefore, in the present invention, by setting the Vickers hardness Hv of the weld metal to 220 or more, it is possible to ensure sufficient joint strength even in electrogas arc welding of a steel material having a plate thickness of 40 mm or more.
以下、本発明の溶接金属の組成規定理由について、説明する。 Hereinafter, the reason for defining the composition of the weld metal of the present invention will be described.
「Ｃ：０．０５乃至０．０７質量％」
Ｃは溶接金属の強度を確保するためには欠かせない元素である。Ｃの質量が０．０５質量％未満では、溶接金属の強度が低下し、継手引張強度を確保できない。一方、Ｃが０．０７質量％を超えると、溶接金属の強度が高くなり過ぎ、靱性が劣化する。
“C: 0.05 to 0.07 mass%”
C is an element indispensable for ensuring the strength of the weld metal. If the mass of C is less than 0.05% by mass, the strength of the weld metal decreases, and the joint tensile strength cannot be ensured. On the other hand, when C exceeds 0.07 mass%, the strength of the weld metal becomes too high and the toughness deteriorates.
「Ｓｉ：０．１０乃至０．３０質量％」
Ｓｉは脱酸剤として溶接金属の酸素量を低減し、靭性を向上させる。Ｓｉの質量が０．１０質量％未満では、溶接金属の靭性が劣化する。一方、Ｓｉの質量が０．３０質量％を超えると、強度が高くなり、靱性が劣化する。
“Si: 0.10 to 0.30 mass%”
Si acts as a deoxidizer to reduce the oxygen content of the weld metal and improve toughness. When the mass of Si is less than 0.10% by mass, the toughness of the weld metal deteriorates. On the other hand, when the mass of Si exceeds 0.30 mass%, the strength increases and the toughness deteriorates.
「Ｍｎ：１．４０乃至１．８０質量％」
Ｍｎは脱酸剤として溶接金属の酸素量を低減し、靭性を向上させると共に、溶接金属の強度を確保するにためにも有効な元素である。Ｍｎの質量が１．４０質量％未満では、溶接金属の強度が低下し、継手引張強度が確保できない。一方、Ｍｎの質量が１．８０質量％を超えると、溶接金属の強度が高くなり過ぎ、靱性が劣化する。
“Mn: 1.40 to 1.80 mass%”
Mn is an effective element for reducing the oxygen content of the weld metal as a deoxidizer, improving toughness, and ensuring the strength of the weld metal. If the mass of Mn is less than 1.40 mass%, the strength of the weld metal is lowered, and the joint tensile strength cannot be ensured. On the other hand, when the mass of Mn exceeds 1.80 mass%, the strength of the weld metal becomes too high and the toughness deteriorates.
「Ｎｉ：０．９乃至１．３質量％」
Ｎｉはオーステナイト形成元素であり、前述したとおり、溶接金属の靭性を安定化させる効果がある。Ｎｉの質量が０．９質量％未満では、溶接金属の靱性が劣化する。一方、Ｎｉが１．３質量％を超えると、強度が高くなり過ぎ、靱性が劣化する。
“Ni: 0.9 to 1.3 mass%”
Ni is an austenite forming element and has the effect of stabilizing the toughness of the weld metal as described above. When the mass of Ni is less than 0.9% by mass, the toughness of the weld metal deteriorates. On the other hand, if Ni exceeds 1.3% by mass, the strength becomes too high and the toughness deteriorates.
「Ｍｏ：０．４乃至０．６質量％」
Ｍｏはフェライト形成元素であり、溶接金属の焼入れ性を高める効果があり、凝固組織の微細化に有効な元素である。従って、靭性を向上させ、更には少量のＭｏ添加でも、溶接金属の強度を高めることができる。Ｍｏの質量が０．４質量％未満では、溶接金属の強度が低下し、継手強度を確保できない。一方、Ｍｏが０．６質量％を超えると、溶接金属の強度が高くなり、靭性が劣化する。
“Mo: 0.4 to 0.6 mass%”
Mo is a ferrite-forming element, has an effect of improving the hardenability of the weld metal, and is an element effective for refinement of a solidified structure. Therefore, the toughness can be improved, and even the addition of a small amount of Mo can increase the strength of the weld metal. If the mass of Mo is less than 0.4% by mass, the strength of the weld metal decreases, and the joint strength cannot be ensured. On the other hand, when Mo exceeds 0.6 mass%, the strength of the weld metal increases and the toughness deteriorates.
このように、Ｍｏは溶接金属の焼入れ性を高める効果があり、組織微細化に有効であるが、Ｍｏを過度に添加すると、強度が高くなり過ぎ、靱性が劣化する。一方で、Ｎｉは靭性の安定化に有効であるが、Ｎｉを過度に添加すると、オーステナイト凝固となり、靭性が劣化する。本発明のＮｉ，Ｍｏの含有量範囲においては、オーステナイト形成元素のＮｉを添加して靱性の安定化を図り、フェライト形成元素であるＭｏを添加することによりオーステナイト凝固を抑制しつつ組織の微細化を行う。これにより、継手強度確保のための溶接金属強度を維持しつつ、溶接金属強度の上昇による靭性劣化を抑制することができ、本発明は、強度及び靭性が共に優れた溶接金属を得ることができる組成範囲を開示したものである。 Thus, Mo has the effect of improving the hardenability of the weld metal and is effective for refining the structure. However, when Mo is added excessively, the strength becomes too high and the toughness deteriorates. On the other hand, Ni is effective in stabilizing toughness, but if Ni is added excessively, austenite solidification occurs and the toughness deteriorates. In the Ni and Mo content range of the present invention, the austenite forming element Ni is added to stabilize the toughness, and the ferrite forming element Mo is added to suppress the austenite solidification and refine the structure. I do. Thereby, while maintaining the weld metal strength for securing the joint strength, it is possible to suppress toughness deterioration due to an increase in weld metal strength, and the present invention can obtain a weld metal having both excellent strength and toughness. The composition range is disclosed.
「Ｔｉ：０．０３乃至０．０６質量％」
ＴｉはＢとの相乗効果により溶接金属組織を微細化し、靱性を向上させる効果がある。Ｔｉの質量が０．０３質量％未満では、組織の微細化効果が得られず、溶接金属の靱性が劣化する。一方、Ｔｉが０．０６質量％を超えると、溶接金属中にＴｉが過剰となり、靭性が劣化する。
“Ti: 0.03 to 0.06 mass%”
Ti has the effect of refining the weld metal structure and improving toughness by a synergistic effect with B. When the mass of Ti is less than 0.03% by mass, the effect of refining the structure cannot be obtained, and the toughness of the weld metal deteriorates. On the other hand, when Ti exceeds 0.06 mass%, Ti becomes excessive in the weld metal and the toughness deteriorates.
「Ｂ：０．００２乃至０．００６質量％」
Ｂは少量の添加でＴｉとの相乗効果により溶接金属組織を微細化し、靭性を向上させる効果がある。Ｂの質量が０．００２質量％未満では、組織の微細化効果が得られず、溶接金属の靭性が劣化する。一方、Ｂが０．００６質量％を超えると、溶接金属中にＢが過剰となり、強度が高くなり過ぎ靱性が劣化する。
“B: 0.002 to 0.006 mass%”
B has the effect of refining the weld metal structure and improving toughness by a synergistic effect with Ti with a small amount of addition. If the mass of B is less than 0.002 mass%, the effect of refining the structure cannot be obtained, and the toughness of the weld metal deteriorates. On the other hand, if B exceeds 0.006% by mass, B becomes excessive in the weld metal, the strength becomes too high, and the toughness deteriorates.
「Ｏ：０．０４質量％以下」
溶接金属のＯ量が高いと、靭性は劣化するので、Ｏを０．０４質量％以下に規制する。
“O: 0.04 mass% or less”
When the amount of O of the weld metal is high, toughness deteriorates, so O is regulated to 0.04 mass% or less.
「Ｎ：０．００７５質量％以下」
溶接金属のＮ量が高いと、靱性は劣化するので、Ｎを０．００７５質量％以下に規制する。
“N: 0.0075 mass% or less”
If the N amount of the weld metal is high, toughness deteriorates, so N is regulated to 0.0075 mass% or less.
「Ａｌ：０．０２質量％以下」
溶接金属のＡｌ量が高いと、Ｔｉ酸化物による組織微細化効果が抑制され、靱性は劣化するので、Ａｌは０．０２質量％以下に規制する。
“Al: 0.02 mass% or less”
When the Al content of the weld metal is high, the effect of refining the structure due to the Ti oxide is suppressed and the toughness deteriorates, so Al is restricted to 0.02% by mass or less.
「Ｐ：０．０２質量％以下」
溶接金属のＰ量が高いと高温割れが発生しやすくなるので、Ｐは０．０２質量％以下に規制する。
“P: 0.02 mass% or less”
If the P content of the weld metal is high, hot cracking is likely to occur, so P is restricted to 0.02 mass% or less.
「Ｓ：０．０２質量％以下」
溶接金属のＳ量が高いと、高温割れが発生しやすくなるので、Ｓは０．０２質量％以下に規制する。
“S: 0.02 mass% or less”
If the amount of S in the weld metal is high, hot cracking is likely to occur, so S is restricted to 0.02 mass% or less.
「Ｃｕ：０．２質量％以下」
溶接金属のＣｕは、強度を高める効果はあるものの、過度に添加すると強度が高くなり過ぎ、靱性が劣化するため、意図的には添加しない。但し、鋼材の希釈及びワイヤのメッキにより、不可避的に０．２質量％以下は含まれることがあり、この程度は許容される。
“Cu: 0.2% by mass or less”
Although there is an effect of increasing the strength, Cu of the weld metal is not intentionally added because excessively added strength results in excessively high strength and deteriorates toughness. However, 0.2% by mass or less may be inevitably included due to dilution of the steel material and plating of the wire, and this degree is allowed.
「Ｃｒ：０．０５質量％以下」
溶接金属のＣｒはフェライト形成元素であり、溶接金属の焼入れ性を高める効果があるが、その効果はＭｏと比較して小さく、このため、Ｃｒは意図的には添加しない。但し、鋼材の希釈により、Ｃｒが不可避的に０．０５質量％以下含まれることがあり、この程度は許容される。
“Cr: 0.05% by mass or less”
Cr in the weld metal is a ferrite-forming element and has the effect of improving the hardenability of the weld metal, but the effect is small compared to Mo, and therefore Cr is not added intentionally. However, due to dilution of the steel material, Cr may inevitably be contained in an amount of 0.05% by mass or less, and this degree is allowed.
「ビッカース硬度Ｈｖ：２２０乃至２３５」
溶接金属の強度が低いと、継手の強度を確保できない。本発明者らが鋭意検討した結果、溶接金属の硬さＨｖが２２０未満であると、板厚が４０ｍｍ以上の鋼材をエレクトロガスアーク溶接した場合、熱影響部が軟化し、継手強度を確保できない。溶接金属の硬さがＨｖ２２０以上であると、溶接金属部の拘束力により、熱影響部の塑性変形が抑制され、継手強度が目標の５７０Ｎ／ｍｍ２以上を満足する。一方、溶接金属の硬さＨｖが２３５を超えると、溶接金属の組織がベイナイト＋マルテンサイト組織となるため、継手強度は目標を満足するが、溶接金属の強度が高くなり過ぎ、靱性が劣化する。
“Vickers hardness Hv: 220 to 235”
If the strength of the weld metal is low, the strength of the joint cannot be secured. As a result of intensive studies by the present inventors, when the hardness Hv of the weld metal is less than 220, when a steel material having a plate thickness of 40 mm or more is electrogas arc welded, the heat-affected zone is softened and the joint strength cannot be ensured. When the hardness of the weld metal is Hv 220 or more, the plastic deformation of the heat-affected zone is suppressed by the binding force of the weld metal portion, and the joint strength satisfies the target of 570 N / mm 2 or more. On the other hand, when the hardness Hv of the weld metal exceeds 235, the weld metal structure becomes a bainite + martensite structure, so the joint strength satisfies the target, but the weld metal strength becomes too high and the toughness deteriorates. .
なお、溶接金属の硬さは、溶接金属の成分濃度から決まるパラメータＰＣＭを、０．２００乃至０．３５０の範囲内に規定することと、溶接入熱を２００ｋＪ／ｃｍ乃至４６０ｋＪ／ｃｍの範囲に調整して溶接施工することにより制御する。即ち、溶接金属中の化学成分の含有量から、下記数式ＰＣＭの値を算出する。 The hardness of the weld metal is determined by defining the parameter PCM determined from the component concentration of the weld metal within the range of 0.200 to 0.350 and the welding heat input within the range of 200 kJ / cm to 460 kJ / cm. Control by adjusting and welding. That is, the value of the following mathematical formula PCM is calculated from the content of chemical components in the weld metal.
溶接金属の残部としては、Ｆｅ及び母材の希釈により混入するＮｂ，Ｖの他、不可避的不純物がある。なお、残部のうち、Ｆｅは９０質量％以上含有されている。 As the balance of the weld metal, there are unavoidable impurities in addition to Nb and V mixed by dilution of Fe and the base material. In addition, 90 mass% or more of Fe is contained among remainders.
一般的に、鋼材をエレクトロガスアーク溶接する場合、鋼材希釈率が２０乃至３０質量％程度であるため、本発明の溶接金属化学成分範囲に制御するには、４６０Ｎ／ｍｍ２以上の鋼材成分及びエレクトロガスアーク溶接用ワイヤの成分で調整を行う。 Generally, when steel material is electrogas arc welded, the steel material dilution ratio is about 20 to 30% by mass. Therefore, in order to control the range of the weld metal chemical component of the present invention, the steel material component of 460 N / mm 2 or more and electro Adjustments are made with the components of the gas arc welding wire.
以下、本発明の実施例について、本発明の範囲から外れる比較例と比較して説明する。下記表１は供試鋼板の組成（質量％）を示す。この供試鋼板は、降伏強度が４６０Ｎ／ｍｍ２以上であり、板厚は４０〜６０ｍｍ、幅は５００ｍｍ、長さは１０００ｍｍの大きさを有する。そして、下記表２（試験条件）及び表３（溶接施工条件）に示す条件で、１パス溶接を行った。なお、ワイヤ径は１．６ｍｍである。 Examples of the present invention will be described below in comparison with comparative examples that are out of the scope of the present invention. Table 1 below shows the composition (mass%) of the test steel sheet. This test steel plate has a yield strength of 460 N / mm 2 or more, a plate thickness of 40 to 60 mm, a width of 500 mm, and a length of 1000 mm. And 1 pass welding was performed on the conditions shown in the following Table 2 (test conditions) and Table 3 (welding construction conditions). The wire diameter is 1.6 mm.
溶接金属の衝撃試験については、ＪＩＳ Ｚ ３１２８に規定されている方法により、−２０℃における衝撃値を測定し、３本の衝撃値の平均値が５３Ｊ以上のものを、衝撃性能が良好と判断した。溶接金属の硬さは、図１に示すように、溶接金属１の中央部の位置で矢印２に示すように、板厚方向に２ｍｍ間隔でビッカース硬さを測定し、その平均値をビッカース硬さとした。なお、符号３は溶接母材である。板厚が４０ｍｍの場合は２１点、５０ｍｍの場合は２６点、５５ｍｍの場合は２８点、６０ｍｍの場合は３１点の夫々について測定した。溶接継手引張試験片は、ＮＫＵ２Ａ号試験片を用い、継手強度が５７０Ｎ／ｍｍ２以上を良好とした。
For the weld metal impact test, the impact value at −20 ° C. is measured by the method specified in JIS Z 3128, and the impact performance is judged to be good if the average value of the three impact values is 53 J or more. did. As shown in FIG. 1, the hardness of the weld metal is measured at 2 mm intervals in the plate thickness direction as indicated by an
下記表４（表４−１、表４−２）はワイヤの化学組成（質量％）を示す。表４に示す組成のワイヤ１〜２１と、表１に示す板厚の供試鋼板とを種々組合せてエレクトロガスアーク溶接を行った。下記表５（表５-１，表５−２）は、溶接金属の化学組成（質量％）を示す。更に、下記表６は、実施例及び比較例の機械的性能を示す。 The following Table 4 (Table 4-1 and Table 4-2) shows the chemical composition (mass%) of the wire. Electrogas arc welding was performed by variously combining the wires 1 to 21 having the compositions shown in Table 4 and the test steel plates having the thicknesses shown in Table 1. Table 5 below (Tables 5-1 and 5-2) shows the chemical composition (mass%) of the weld metal. Furthermore, Table 6 below shows the mechanical performance of the examples and comparative examples.
本発明の実施例１〜１４では、溶接金属の強度は適正範囲内でかつ機械的性能を満足した。比較例１５では、溶接金属のＣ量が０．０５質量％未満、Ｓｉ量が０．１０質量％未満、Ｔｉ量が０．０３質量％未満であり、ビッカース硬さがＨｖ２２０未満であり、継手強度が低く、靭性も劣化した。比較例１６では、溶接金属のＣ量が０．０７質量％を超え、Ｓｉ量が０．３０質量％を超え、Ｍｎ量が１．８０質量％を超えており、強度が高くなり過ぎ靱性が劣化した。比較例１７では、溶接金属のＮｉ量が１．３質量％を超え、Ｍｏ量が０．６質量％を超えており、強度が高くなり過ぎ靭性が劣化した。比較例１８では、溶接金属のＴｉ量が０．０６質量％を超え、Ｂ量が０．００６質量％を超えており、Ｔｉ，Ｂ量が過剰となり靱性が劣化した。比較例１９では、溶接金属のＢ量が０．００２質量％未満であり、靭性が劣化した。比較例２０では、溶接金属のＮｉ量が０．９質量％未満であり、靭性が劣化した。比較例２１では、溶接金属のＭｎ量が１．４０質量％未満であり、Ｍｏ量が０．４質量％未満であり、ビッカース硬さがＨｖ２２０未満であり、継手強度が低くなった。 In Examples 1 to 14 of the present invention, the strength of the weld metal was within an appropriate range and satisfied the mechanical performance. In Comparative Example 15, the C amount of the weld metal is less than 0.05% by mass, the Si amount is less than 0.10% by mass, the Ti amount is less than 0.03% by mass, the Vickers hardness is less than Hv220, Low strength and toughness deteriorated. In Comparative Example 16, the C amount of the weld metal exceeds 0.07 mass%, the Si amount exceeds 0.30 mass%, the Mn amount exceeds 1.80 mass%, the strength becomes too high and the toughness is too high. Deteriorated. In Comparative Example 17, the amount of Ni in the weld metal exceeded 1.3% by mass, the amount of Mo exceeded 0.6% by mass, the strength became too high, and the toughness deteriorated. In Comparative Example 18, the Ti amount of the weld metal exceeded 0.06 mass%, the B amount exceeded 0.006 mass%, the Ti and B amounts became excessive, and the toughness deteriorated. In Comparative Example 19, the B amount of the weld metal was less than 0.002% by mass, and toughness deteriorated. In Comparative Example 20, the amount of Ni in the weld metal was less than 0.9% by mass, and the toughness was deteriorated. In Comparative Example 21, the Mn content of the weld metal was less than 1.40 mass%, the Mo content was less than 0.4 mass%, the Vickers hardness was less than Hv220, and the joint strength was low.
１：溶接金属
２：矢印
３：溶接母材
1: Weld metal 2: Arrow 3: Welding base material
Claims (1)
溶接金属の化学組成が、
Ｃ：０．０５乃至０．０７質量％
Ｓｉ：０．１０乃至０．３０質量％
Ｍｎ：１．４０乃至１．８０質量％
Ｎｉ：０．９乃至１．３質量％
Ｍｏ：０．４乃至０．６質量％
Ｔｉ：０．０３乃至０．０６質量％
Ｂ：０．００２乃至０．００６質量％
を含有し、
Ｐ：０．０２質量％以下
Ｓ：０．０２質量％以下
Ｃｕ：０．２質量％以下
Ｃｒ：０．０５質量％以下
Ａｌ：０．０２質量％以下
Ｏ：０．０４質量％以下
Ｎ：０．００７５質量％以下
に規制し、
残部がＦｅ及び不可避的不純物からなるものであり、
かつ溶接金属の硬さがビッカース硬度でＨｖ：２２０乃至２３５であることを特徴とする溶接継手。 A welded joint obtained by electrogas arc welding of a steel material having a yield strength of 460 N / mm 2 or more,
The chemical composition of the weld metal
C: 0.05 to 0.07% by mass
Si: 0.10 to 0.30 mass%
Mn: 1.40 to 1.80 mass%
Ni: 0.9 to 1.3% by mass
Mo: 0.4 to 0.6% by mass
Ti: 0.03 to 0.06 mass%
B: 0.002 to 0.006 mass%
Containing
P: 0.02 mass% or less S: 0.02 mass% or less Cu: 0.2 mass% or less Cr: 0.05 mass% or less Al: 0.02 mass% or less O: 0.04 mass% or less N: Restricted to 0.0075 mass% or less,
The balance consists of Fe and inevitable impurities,
The weld joint has a Vickers hardness of Hv: 220 to 235.
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