JP3892781B2 - Flux-cored wire for gas shielded arc welding of low alloy steel with excellent hydrochloric acid resistance and sulfuric acid resistance - Google Patents
Flux-cored wire for gas shielded arc welding of low alloy steel with excellent hydrochloric acid resistance and sulfuric acid resistance Download PDFInfo
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Description
【０００１】
【発明の属する技術分野】
本発明は、石炭焚きボイラーやごみ焼却施設の煙道、煙突のように硫酸および塩酸による低温腐食を生じるような雰囲気、すなわち濃厚硫酸および塩酸環境で優れた耐食性を示す耐硫酸露点腐食低合金鋼用の溶接材料に関するものである。より詳しくは、これらの鋼を重油、石炭などの化石燃料、液化天然ガスなどのガス燃料、都市ごみなどの一般廃棄物、および木工屑、繊維屑、廃油、プラスチック、排タイヤ、医療廃棄物などの産業廃棄物および下水汚泥などを燃焼させるボイラーの排煙設備、すなわち煙道ダクト、ケーシング、熱交換器、回転再生式空気予熱器のバスケット材および伝熱エレメント板、減温塔、バグフィルター、煙突などに溶接施工して使用する場合好適で、経済性にも優れた溶接材料、または、塩酸、硫酸などの単独または混合の酸洗液を収める鋼製めっき酸洗槽用の耐酸性に優れたガスシールドアーク溶接用フラックス入りワイヤ（以下ワイヤ）に関する。
【０００２】
【従来の技術】
一般に溶接構造物が腐食環境で使用される場合、溶接部と母材との間で耐食性に差異があると、耐食性の劣る方が選択的に腐食され、構造物の寿命が著しく短くなる。また、溶接部が選択的に腐食すると、腐食孔に応力集中が生じ、極端な場合は構造物の破壊を招く恐れもある。このように、溶接構造物の利用において、腐食劣化が無視できない用途の場合には、母材だけでなく溶接部の耐食性も十分に確保する必要がある。
【０００３】
石炭焚き火力やごみ焼却施設などの煙道、煙突などの排煙設備では、排ガス中の三酸化硫黄および塩化水素に起因して、硫酸露点腐食、塩酸露点腐食が生じる。このような環境に対して、耐硫酸露点腐食鋼（例えば、新日本製鐵株式会社、S-TEN製品カタログ、Cat．No．AC107、 1981．6版）が使用されている。溶接材料としては、軟鋼用の溶接材料や耐硫酸露点腐食鋼専用の溶接材料（例えば、日鐵溶接工業株式会社 ニッテツ溶接材料・機器ハンドブック、p２１０）が使われている。
【０００４】
耐硫酸露点腐食鋼専用の溶接材料は、耐食元素としてＣｕを単独で含む材料や、Ｃｕ−Ｃｒを含む材料であった。これらの既存の溶接材料を使用した場合、これらは、重油専焼ボイラのプラント排煙装置で生じる硫酸露点腐食環境では十分に優れた耐食性を示すが、 石炭焚きボイラやごみ焼却またはごみのガス化溶融施設などでは、硫酸露点腐食と塩酸露点腐食が同時に生じるため、溶接部の耐食性が十分でないといった問題があった。
【０００５】
これまでに、塗装鋼板における腐食性が提案されている（例えば、特開昭５９−４５０９６号公報参照）。さらに、スラグ剥離性のよいガスシールドアーク溶接用フラックス入りワイヤが提案されている（例えば、特開昭６１−２６２４９１号公報参照）が、耐硫酸露点腐食鋼における耐食性については考慮されていない。
【０００６】
【発明が解決しようとする課題】
本発明は、このような問題を解決するためになされたもので、その目的とするところは、耐塩酸性および耐硫酸性に優れ、かつ良好な溶接作業性を確保できるガスシールドアーク溶接用フラックス入りワイヤを提供することにある。
【０００７】
【課題を解決するための手段】
本発明者らは、耐硫酸露点腐食性と耐塩酸露点腐食性に及ぼす冶金因子を詳細に検討した結果、鋼製外皮と充填フラックスとからなるフラックス入りワイヤのワイヤ全体の組成を特定することにより、耐食性に優れた溶接金属が得られることを知見した。すなわち、まず、不純物であるＰ，Ｓを限定した上で、(1)特定のＣ−Ｓｉ−Ｃｕ−Ｎｉ−Ｓｂとすることにより、優れた耐硫酸性および耐塩酸性の溶接金属が得られる、(2)前記(1)の成分系にＭｏを添加すると、耐塩酸性が飛躍的に向上させることができる、(3)前記(1)または(2)の成分系にさらに、Ｃｒを添加すると、酸化性雰囲気での耐高濃度硫酸性を向上させることができる、（４）前記（１）、（２）または（３）の成分系でさらに充填フラックス中のＳｂの平均粒径を４５〜１５０μｍにすることにより、良好な溶接作業性が得られる、というものである。本発明は、これらの知見に基づいて本発明を完成させたもので、その要旨とするところは以下の通りである。
【０００８】
（１）鋼製外皮内に充填フラックスを充填してなるフラックス入りワイヤにおいて、ワイヤ全質量に対する質量％で、前記鋼製外皮中または充填フラックス中の一方又は両方に、
Ｃ ： ０．００５〜０．１５％、
Ｓｉ：０．１〜２％、
Ｍｎ：０．２〜３％、
Ｃｕ：０．１〜１％、
Ｎｉ：０．１〜０．６５％、
Ｓｂ：０．０１〜０．５％
を含有し、
かつ、Ｐ ：０．０３％以下、
Ｓ ：０．０３％以下に制限し、
残部がＦｅおよび不可避的不純物であることを特徴とする耐塩酸性および耐硫酸性に優れた耐硫酸性鋼のガスシールドアーク溶接用フラックス入りワイヤ。
【０００９】
（２）前記ワイヤ全質量に対する質量％で、前記鋼製外皮中または充填フラックス中の一方または両方に、Ｓ：０．００５〜０．０３％を含有することを特徴とする（１）記載の耐塩酸性および耐硫酸性に優れた低合金鋼のガスシールドアーク溶接用フラックス入りワイヤ。
【００１０】
（３）前記鋼製外皮中または充填フラックス中の一方又は両方に、さらに、
Ｍｏ：０．０１〜０．５％
を含有することを特徴とする（１）または（２）に記載の耐塩酸性および耐硫酸性に優れた耐硫酸性鋼のガスシールドアーク溶接用フラックス入りワイヤ。
【００１２】
（４）前記充填フラックス全質量に対する質量％で、充填フラックス中に、
金属酸化物：３０〜６５％ 、
鉄粉 ：１０〜３０％を含有することを特徴とする（１）〜（３）のいずれか１つに記載の耐塩酸性および耐硫酸性に優れた低合金鋼のガスシールドアーク溶接用フラックス入りワイヤ。
【００１３】
（５）前記充填フラックス中のＳｂの平均粒径が４５〜１５０μｍであることを特徴とする（１）〜（４）のいずれか１つに記載の耐塩酸性および耐硫酸性に優れた低合金鋼のガスシールドアーク溶接用フラックス入りワイヤ。
【００１４】
【発明の実施の形態】
本発明のワイヤは、鋼製外皮に充填フラックスを充填してなるものであるが、所要の特性を有する溶接金属を得るための各元素は、鋼製外皮、充填フラックスのいずれから添加しても良い。従って、各元素は、以下の説明においては、特に断りのない限り、鋼製外皮および充填フラックスのいずれか一方または双方において、フラックス入りワイヤ全体として含有させれば良い。
【００１５】
ワイヤ全質量に対する各含有量規定について述べる。なお、％は、特に断りのない限り質量％である。
【００１６】
Ｃは、溶接構造用鋼の溶接継手として強度を確保するために添加するが、０．１５％を超えて添加すると、溶接性および耐硫酸性が低下する。耐硫酸性および耐塩酸性の観点ではＣの含有量は少ないほど好ましい。しかしＣを０．００５％未満に低減するには、多大なコストを要する一方、強度が確保できなくなるので、０．００５％以上とするのが好ましく、さらに強度や経済性を考慮すると０．０１〜０．１％が好ましい。特に、Ｍｏと共存する場合、０．１％を超えるＣ添加は耐硫酸性を著しく低下させる。耐塩酸性と耐硫酸性とのバランスを考慮する必要がある場合は、０．０５％以下が最も好ましい。
【００１７】
Ｓｉは、溶接金属中に０．１％以上含まれると、Ｃｕと共存して特に４０％程度の硫酸濃度域での耐硫酸性および耐塩酸性を向上させる。２％を超えると、耐食性の向上はみられず、溶接金属の靭性が著しく低下するので、上限を２％とした。溶接施工性や溶接部の靭性をより重視する場合は、０．５〜２％が好ましい。
【００１８】
Ｍｎは、脱酸および強度調整のため０．２％以上添加するが、その上限は３％で十分であるので、０．２〜３％を限定範囲とした。
【００１９】
Ｐは、不純物元素であり、耐硫酸性および耐塩酸性を著しく阻害するので、その範囲を０．０３％以下とした。より好ましくは、０．０１％以下に限定すると耐硫酸性および耐塩酸性が著しく改善される。０．００５〜０．０１％がより好ましく、０．００５％以下が最も好ましい。
【００２０】
Ｓは、不純物元素であり、十分な耐硫酸性および耐塩酸性を確保する上で限定する必要がある。０．０３％を超えると、耐硫酸性が著しく低下するので上限を０．０３％とした。また、Ｃｕ−Ｍｏ−Ｓｂ系の溶接金属においては、Ｓを０．００５％以上含有させると耐硫酸性と共に、耐塩酸性が著しく向上する。しかし、０．０３％を超えて含有させてもその効果は飽和し、また、機械的性質（耐ラメラテア性など）および熱間加工性が低下するので、これらの点から含有量を０．００５〜０．０３％とするのが好ましい。
【００２１】
Ｃｕは、耐硫酸性および耐塩酸性を確保するためには０．１％以上の添加が必須である。１％を超えて添加しても耐食性はほぼ飽和し、過度の強度上昇および製造性の低下を招くため、０．１〜１％を限定範囲とした。好ましくは、０．２５〜０．７５％の添加が耐食性および製造性のバランスにて最も優れている。
【００２２】
なお、Ｃｕはワイヤ表面のめっき成分として添加することも出来る。
【００２３】
Ｎｉは、耐塩酸性の向上および、ＣｕまたはＳｂとの添加で生じる溶接金属凝固時の表面割れ防止を目的に０．１％以上添加する必須元素であるが、０．６５％を超えて添加してもそれらの効果は飽和するので、０．１〜０．６５％を限定範囲とした。０．１％〜Ｃｕ％×０．５の範囲が好ましい。
【００２４】
Ｓｂは、０．０１％以上添加すると、Ｃｕと共存して耐硫酸性および耐塩酸性をさらに向上させる元素である。十分な耐食性を得るには、０．０５％以上の添加が好ましい。一方、０．５％を超えるとアーク状態が劣化するので０．０１〜０．５％に限定した。
【００２５】
さらに、本発明においては、フラックス中のＳｂの平均粒径も必要に応じて限定する。４５μｍ未満ではスラグの粘性が下がり、１５０μｍを超えると偏析しやすくなり、溶着金属中のＳｂ量が安定せず耐食性にバラツキが生じるようになる。よって、好ましくはＳｂの平均粒径を４５〜１５０μｍの範囲に限定する。
【００２６】
Ｍｏは、Ｃｕとともに０．０１％以上添加すると、溶接金属の耐塩酸性を著しく向上させる元素であり、必要に応じて添加する。その効果はＣｕ−Ｓｂとの複合添加で更に増大する。０．５％を超えて添加すると、耐塩酸性および耐硫酸性が低下するので、０．０１〜０．５％に限定した。Ｍｏの最適添加量は０．０５％であることから、０．０２５〜０．０７５％が最も好ましい。
【００２７】
Ｃｒは、特に排ガス中の硫黄酸化物含有量の多いプラントで生じる酸化性の硫酸露点腐食環境での耐食性を確保するために、必要に応じて、０．５％以上添加する。その効果は１．５％を超えて添加すると、逆に耐食性が阻害されるので、１．５％以下に限定した。一方、Ｃｒは、０．１％以上添加すると耐塩酸性を阻害する元素であり、酸化性の硫酸露点腐食環境でない場合は、Ｃｒは無添加、すなわち０．１％未満が好ましい。
【００２８】
なお、本発明の限定要件ではないが、更に必要に応じて、Ａｌ，Ｔｉ，Ｎｂ，Ｖ，Ｔａ，Ｗ，Ｓｎ，ＲＥＭ，Ｃａの元素を添加してもよい。なお、Ｓｎは、添加または不可避的不純物として含有しても溶接金属の耐硫酸露点腐食性および耐塩酸露点腐食性を阻害するものではないが、０．０５％を超えると、溶接継手の靭性を著しく低下させるので、０．０５％以下に制限することが好ましい。
【００２９】
次に、充填フラックス中の金属酸化物および鉄粉の添加量について述べる。
【００３０】
金属酸化物は、ＳｉＯ2 ，ＴｉＯ2 ，Ｎａ2 Ｏ，Ａｌ2 Ｏ3 などであり、溶接時のアーク状態とスラグ状態を良好に維持するために、フラックス中に１種または２種以上の組み合わせで添加するのが好ましい。それらの合計含有量が３０％未満ではアーク安定性とスラグ状態を良好に維持できず、一方、６５％を超えると溶融金属中の酸素が多くなり靭性が低下する。
【００３１】
したがって、フラックス中の金属酸化物の含有量は３０〜６５％とするのが好ましい。
【００３２】
鉄粉は、溶接能率の向上、または、充填率の調整のために充填フラックス中に添加し、その含有量が１０％未満ではこれらの効果が十分発揮できず、逆に３０％を超えるとアーク状態の劣化を招き溶接作業性が悪くなる。
【００３３】
したがって、フラックス中の鉄粉の含有量は１０〜３０％とするのが好ましい。
【００３４】
本発明では、フラックスの充填率は特に限定されないが、溶接作業性やワイヤ製造時の伸線性を考慮して、ワイヤ重量に対して１０〜３０％の範囲が最も適当である。また。ワイヤの断面形状は、Ｃ断面、重ね断面等の合わせ目あり、または合わせ目のないシームレスタイプでもよく、シームレスワイヤにおいては表面にＣｕ等のめっき処理を施すことも有効である。
【００３５】
なお、本発明のフラックス入りワイヤの鋼製外皮の厚さ、ワイヤの径は、特に限定されるものではなく、適宜選択することができる。
【００３６】
【実施例】
本発明を実施例で更に詳細に説明する。表１に示した組成を有する鋼製外皮に表２、表３（表２のつづき）に示したフラックスを充填後、伸線し、１．２mmφに仕上げてフラックス入りワイヤを作成した。ワイヤ全体の成分組成を表２、表３に示す。
【００３７】
【表１】
【表２】
【表３】
表２のワイヤを用い、以下の試験条件で多層盛り溶接を行ない試験片を採取して、溶着金属の硫酸及び塩酸の耐食性試験と溶接作業性調査を行い判定した。耐食性試験に使用した試験片は、図１に示すように作成した。すなわち、母材成分の影響を受けないように、軟鋼母材３上に電流２７０Ａ、電圧２７Ｖで９層で盛上げ４を形成し、５層目から溶着金属２を機械加工で試験片１（４mm×２５mm×２５mm）を各４個採取した。
【００４１】
腐食試験は、４０℃の２０％硫酸で２４時間、及び８０℃の１０％塩酸で２４時間の浸漬腐食試験を行い、各試験片４個の平均腐食減量を求め、共に２．５ｍｇ／（ｃｍ2・ｈｒ）以下を良好、２．５ｍｇ／（ｃｍ2・ｈｒ）をやや劣る、１１ｍｇ／（ｃｍ2・ｈｒ）以上を劣る、とした。
【００４２】
溶接作業性の調査では、板厚１２ｍｍ、幅１００ｍｍ、長さ４５０ｍｍの軟鋼をＴ型に組み、水平隅肉では電流２７０Ａ、電圧２７Ｖ、立向姿勢では電流２２０Ａ、電圧２０Ｖで溶接作業を行ない、アーク状態、スラグ状態、スパッタの多少、ビード形状などを調査した。その判定は、各姿勢での評価を総合判定し、良好を○、やや劣るを△、劣るを×とした。
【００４３】
その試験結果を表４に示す。
【００４４】
【表４】
ワイヤＮｏ．１〜Ｎｏ．３、Ｎｏ．５、Ｎｏ．８〜Ｎｏ．１０、Ｎｏ．１４〜Ｎｏ．１６は本発明例であり、各条件が適正であるので耐硫酸及び耐塩酸での腐食減量が少なく、良好な結果であり、溶接作業性も満足できるものであった。
【００４６】
ワイヤＮｏ．１７〜Ｎｏ．２４は比較例であり、Ｎｏ．１７とＮｏ．１８はＳｂの平均粒径が適正でない場合で、Ｎｏ．１７はフラックス中のＳｂの平均粒径が小さいのでスラグの粘性が低下し立向溶接でビードがたれやすくなり、Ｃｕが少ないので耐食性が劣っていた。また、Ｎｏ．１８はＳｂの平均粒径が大きすぎることとＮｉが低いので耐食性がやや悪くなった。
【００４７】
Ｎｏ．１９は、Ｓｉが少ないので溶接作業性が悪く、また、Ｓが多すぎるので硫酸での耐食性が著しく悪くなった。また、Ｃｕも多いため、機械的強度が大きくなりすぎた。
【００４８】
Ｎｏ．２０は、Ｍｎが多いのでスラグの粘性が低下し、立向溶接でビードがたれやすくなり溶接作業性が劣化し、また、Ｓｂが不足のため、耐硫酸性と耐塩酸性が極めて悪かった。
【００４９】
Ｎｏ．２１は、Ｃが少なくアーク力が弱く、溶接作業性が悪かった。
【００５０】
Ｎｏ．２２は、Ｓｂが添加されていないため、耐硫酸性と耐塩酸性が悪かった。
【００５１】
Ｎｏ．２３は、Ｓｉが多いのでアーク力が強くなりスパッタが増加し、また、Ｐが過剰なため耐硫酸性と耐塩酸性が悪くなった。
【００５２】
Ｎｏ．２４は、耐食性は良好であるが、Ｓｂの添加量が多く、アーク状態が劣化して、溶接作業性がかなり悪くなった。
【００５３】
【発明の効果】
以上説明したように、本発明の溶接用フラックス入りワイヤによれば極めて優れた耐硫酸性と耐塩酸性を有する溶接金属が得られ、かつ溶接作業性の良好な溶接用フラックス入りワイヤを提供することが可能となった。
【図面の簡単な説明】
【図１】（Ａ）腐食試験片の採取要領を示す図。
（Ｂ）（Ａ）のａ−ａ′断面を示す図。
【符号の説明】
１…溶着金属の腐食試験片
２…溶着金属
３…母材
４…盛上げ（９層）[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a sulfuric acid dew point corrosion-resistant low alloy steel exhibiting excellent corrosion resistance in an environment where low temperature corrosion is caused by sulfuric acid and hydrochloric acid such as a flue and a chimney of a coal fired boiler or a garbage incineration facility, that is, concentrated sulfuric acid and hydrochloric acid environment. It relates to a welding material for use. More specifically, these steels are made from heavy oil, fossil fuels such as coal, gas fuels such as liquefied natural gas, municipal waste and other general waste, and woodwork waste, textile waste, waste oil, plastic, exhaust tires, medical waste, etc. Boiler flue gas equipment that burns industrial waste and sewage sludge, such as flue ducts, casings, heat exchangers, basket materials and heat transfer element plates for regenerative air preheaters, temperature reduction towers, bag filters, Suitable for use in welding on chimneys, etc., and excellent in acid resistance for steel plating pickling baths that contain welding materials with excellent economic efficiency, or single or mixed pickling solutions such as hydrochloric acid and sulfuric acid The present invention relates to a flux-cored wire for gas shielded arc welding (hereinafter referred to as a wire).
[0002]
[Prior art]
In general, when a welded structure is used in a corrosive environment, if there is a difference in corrosion resistance between the welded portion and the base metal, the one with inferior corrosion resistance is selectively corroded, and the life of the structure is remarkably shortened. Further, when the welded portion is selectively corroded, stress concentration occurs in the corrosion hole, and in an extreme case, the structure may be destroyed. As described above, in the use of the welded structure, in the case where the corrosion deterioration cannot be ignored, it is necessary to sufficiently ensure not only the base material but also the corrosion resistance of the welded portion.
[0003]
In flue systems such as coal-fired thermal power plants and garbage incineration facilities, such as flue and chimney, sulfuric acid dew point corrosion and hydrochloric acid dew point corrosion occur due to sulfur trioxide and hydrogen chloride in the exhaust gas. In such an environment, sulfuric acid dew point corrosion steel (for example, Nippon Steel Corporation, S-TEN product catalog, Cat. No. AC107, 1981. 6th edition) is used. As a welding material, a welding material for mild steel or a welding material dedicated to sulfuric acid dew-point corrosion steel (for example, Nittetsu Welding Co., Ltd., Nittetsu Welding Materials and Equipment Handbook, p210) is used.
[0004]
The welding material dedicated to sulfuric acid dew-point corrosion steel was a material containing Cu alone as a corrosion-resistant element or a material containing Cu-Cr. When these existing welding materials are used, they exhibit sufficiently good corrosion resistance in the sulfuric acid dew-point corrosion environment generated by the heavy oil oil fired boiler plant flue gas generator, but coal-fired boilers, waste incineration, or gasification and melting of waste In facilities and the like, sulfuric acid dew point corrosion and hydrochloric acid dew point corrosion occur at the same time, resulting in a problem that the corrosion resistance of the welded portion is not sufficient.
[0005]
So far, corrosiveness in coated steel sheets has been proposed (see, for example, JP-A-59-45096). Furthermore, a flux-cored wire for gas shielded arc welding with good slag peelability has been proposed (see, for example, JP-A-61-262491), but the corrosion resistance in sulfuric acid dew-point corrosion steel is not considered.
[0006]
[Problems to be solved by the invention]
The present invention has been made to solve such problems, and the object of the present invention is to provide a flux shield for gas shielded arc welding that is excellent in hydrochloric acid resistance and sulfuric acid resistance and can ensure good welding workability. To provide a wire.
[0007]
[Means for Solving the Problems]
As a result of examining metallurgical factors affecting sulfuric acid dew point corrosion resistance and hydrochloric acid dew point corrosion resistance in detail, the present inventors have identified the composition of the entire wire of the flux-cored wire composed of the steel outer sheath and the filling flux. It has been found that a weld metal having excellent corrosion resistance can be obtained. That is, first, by limiting the impurities P and S, and (1) a specific C—Si—Cu—Ni—Sb, a weld metal having excellent sulfuric acid resistance and hydrochloric acid resistance can be obtained. (2) When Mo is added to the component system of (1), hydrochloric acid resistance can be drastically improved. (3) When Cr is further added to the component system of (1) or (2), (4) In the component system of (1), (2) or (3), the average particle size of Sb in the filled flux is 45 to 150 μm. Thus, good welding workability can be obtained. The present invention has been completed based on these findings, and the gist of the present invention is as follows.
[0008]
(1) In a flux-cored wire formed by filling a steel flux with a filling flux, in one or both of the steel skin or the filling flux in mass% with respect to the total mass of the wire,
C: 0.005-0.15%,
Si: 0.1 to 2%,
Mn: 0.2-3%,
Cu: 0.1 to 1%,
Ni: 0.1 to 0.65%,
Sb: 0.01 to 0.5%
Containing
And P: 0.03% or less,
S: limited to 0.03% or less,
A flux-cored wire for gas shielded arc welding of sulfuric acid-resistant steel excellent in hydrochloric acid resistance and sulfuric acid resistance, wherein the balance is Fe and inevitable impurities.
[0009]
(2) The mass% relative to the total mass of the wire, and S: 0.005 to 0.03% is contained in one or both of the steel outer shell or the filling flux. Flux-cored wire for gas shielded arc welding of low alloy steel with excellent hydrochloric acid resistance and sulfuric acid resistance.
[0010]
(3) In one or both of the steel outer shell or the filling flux,
Mo: 0.01 to 0.5%
The flux-cored wire for gas shielded arc welding of sulfuric acid-resistant steel excellent in hydrochloric acid resistance and sulfuric acid resistance according to (1) or (2), characterized in that
[0012]
( 4 ) In mass% with respect to the total mass of the filling flux,
Metal oxide: 30 to 65%
Iron powder: containing 10 to 30% of flux alloy for gas shielded arc welding of low alloy steel excellent in hydrochloric acid resistance and sulfuric acid resistance according to any one of (1) to ( 3 ) Wire.
[0013]
( 5 ) The low alloy excellent in hydrochloric acid resistance and sulfuric acid resistance according to any one of (1) to ( 4 ), wherein an average particle diameter of Sb in the filled flux is 45 to 150 μm Flux-cored wire for gas shielded arc welding of steel.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
The wire of the present invention is formed by filling a steel outer shell with a filling flux, but each element for obtaining a weld metal having the required characteristics can be added from either the steel outer shell or the filling flux. good. Therefore, in the following description, unless otherwise specified, each element may be contained as a whole flux-cored wire in one or both of the steel outer sheath and the filling flux.
[0015]
Each content regulation with respect to the total wire mass will be described. In addition,% is the mass% unless there is particular notice.
[0016]
C is added to ensure strength as a welded joint for welded structural steel, but if added over 0.15%, weldability and sulfuric acid resistance are reduced. From the viewpoint of sulfuric acid resistance and hydrochloric acid resistance, the smaller the C content, the better. However, in order to reduce C to less than 0.005%, a great deal of cost is required. On the other hand, strength cannot be ensured, so 0.005% or more is preferable. ~ 0.1% is preferred. In particular, when coexisting with Mo, addition of C exceeding 0.1% significantly reduces the sulfuric acid resistance. When it is necessary to consider the balance between hydrochloric acid resistance and sulfuric acid resistance, 0.05% or less is most preferable.
[0017]
When Si is contained in an amount of 0.1% or more in the weld metal, it coexists with Cu and improves sulfuric acid resistance and hydrochloric acid resistance particularly in a sulfuric acid concentration range of about 40%. If it exceeds 2%, the corrosion resistance is not improved, and the toughness of the weld metal is remarkably lowered, so the upper limit was made 2%. When the weldability and the toughness of the welded part are more important, 0.5 to 2% is preferable.
[0018]
Mn is added in an amount of 0.2% or more for deoxidation and strength adjustment, but 3% is sufficient as the upper limit, so 0.2 to 3% was made the limited range.
[0019]
P is an impurity element and significantly inhibits sulfuric acid resistance and hydrochloric acid resistance, so the range was made 0.03% or less. More preferably, when it is limited to 0.01% or less, the sulfuric acid resistance and hydrochloric acid resistance are remarkably improved. 0.005 to 0.01% is more preferable, and 0.005% or less is most preferable.
[0020]
S is an impurity element and needs to be limited to ensure sufficient sulfuric acid resistance and hydrochloric acid resistance. If it exceeds 0.03%, the sulfuric acid resistance is remarkably lowered, so the upper limit was made 0.03%. In addition, in a Cu—Mo—Sb-based weld metal, when 0.005% or more of S is contained, sulfuric acid resistance and hydrochloric acid resistance are remarkably improved. However, even if the content exceeds 0.03%, the effect is saturated, and mechanical properties (such as lamellar resistance) and hot workability are lowered. It is preferable to set it to -0.03%.
[0021]
Cu is required to be added in an amount of 0.1% or more to ensure sulfuric acid resistance and hydrochloric acid resistance. Even if added over 1%, the corrosion resistance is almost saturated, causing an excessive increase in strength and a decrease in manufacturability, so 0.1 to 1% was made the limited range. Preferably, the addition of 0.25 to 0.75% is most excellent in the balance between corrosion resistance and manufacturability.
[0022]
Cu can also be added as a plating component on the wire surface.
[0023]
Ni is an essential element to be added in an amount of 0.1% or more for the purpose of improving hydrochloric acid resistance and preventing surface cracking during solidification of weld metal caused by addition of Cu or Sb, but it is added in excess of 0.65%. However, since those effects are saturated, 0.1 to 0.65% was made the limited range. A range of 0.1% to Cu% × 0.5 is preferable.
[0024]
Sb is an element that, when added in an amount of 0.01% or more, coexists with Cu and further improves sulfuric acid resistance and hydrochloric acid resistance. In order to obtain sufficient corrosion resistance, addition of 0.05% or more is preferable. On the other hand, if it exceeds 0.5%, the arc state deteriorates, so it is limited to 0.01 to 0.5%.
[0025]
Furthermore, in the present invention, the average particle size of Sb in the flux is also limited as necessary. If the thickness is less than 45 μm, the viscosity of the slag decreases, and if it exceeds 150 μm, segregation is likely to occur, and the amount of Sb in the deposited metal is not stable, resulting in variations in corrosion resistance. Therefore, the average particle size of Sb is preferably limited to a range of 45 to 150 μm.
[0026]
Mo is an element that significantly improves the hydrochloric acid resistance of the weld metal when added in an amount of 0.01% or more together with Cu, and is added as necessary. The effect is further increased by the combined addition with Cu-Sb. If added over 0.5%, the hydrochloric acid resistance and sulfuric acid resistance deteriorate, so the content was limited to 0.01 to 0.5%. Since the optimal addition amount of Mo is 0.05%, 0.025 to 0.075% is most preferable.
[0027]
In order to ensure corrosion resistance in an oxidizing sulfuric acid dew point corrosion environment generated in a plant having a high sulfur oxide content in the exhaust gas, Cr is added in an amount of 0.5% or more as necessary. If the effect exceeds 1.5%, the corrosion resistance is adversely affected, so it is limited to 1.5% or less. On the other hand, Cr is an element that inhibits hydrochloric acid resistance when added in an amount of 0.1% or more, and Cr is preferably not added, that is, less than 0.1% in an oxidizing sulfuric acid dew point corrosion environment.
[0028]
Although not a limiting requirement of the present invention, elements of Al, Ti, Nb, V, Ta, W, Sn, REM, and Ca may be added as necessary. Sn does not inhibit the sulfuric acid dew point corrosion resistance and hydrochloric acid dew point corrosion resistance of the weld metal even if added or contained as an unavoidable impurity. However, if it exceeds 0.05%, the toughness of the welded joint will be reduced. It is preferable to limit it to 0.05% or less because it significantly lowers it.
[0029]
Next, the addition amount of the metal oxide and iron powder in the filling flux will be described.
[0030]
The metal oxide is SiO 2 , TiO 2 , Na 2 O, Al 2 O 3, etc., and in order to maintain the arc state and slag state at the time of welding well, one or a combination of two or more in the flux Is preferably added. If the total content thereof is less than 30%, the arc stability and the slag state cannot be maintained satisfactorily. On the other hand, if the total content exceeds 65%, oxygen in the molten metal increases and the toughness decreases.
[0031]
Therefore, the content of the metal oxide in the flux is preferably 30 to 65%.
[0032]
Iron powder is added to the filling flux in order to improve the welding efficiency or to adjust the filling rate. If the content is less than 10%, these effects cannot be exhibited sufficiently. Deterioration of the state causes welding workability to deteriorate.
[0033]
Therefore, the content of iron powder in the flux is preferably 10 to 30%.
[0034]
In the present invention, the filling rate of the flux is not particularly limited, but the range of 10 to 30% with respect to the wire weight is most suitable in consideration of welding workability and wire drawing at the time of wire manufacture. Also. The cross-sectional shape of the wire may be a seamless type with or without a seam such as a C cross-section or an overlap cross-section, and it is also effective to apply a plating treatment such as Cu to the surface of the seamless wire.
[0035]
In addition, the thickness of the steel outer sheath and the wire diameter of the flux-cored wire of the present invention are not particularly limited, and can be appropriately selected.
[0036]
【Example】
The invention is explained in more detail in the examples. A steel sheath having the composition shown in Table 1 was filled with the fluxes shown in Table 2 and Table 3 (continued in Table 2), then drawn and finished to 1.2 mmφ to produce a flux-cored wire. Tables 2 and 3 show the component composition of the entire wire.
[0037]
[Table 1]
[Table 2]
[Table 3]
Using the wires shown in Table 2, multi-layer welding was performed under the following test conditions, specimens were collected, and judged by performing a corrosion resistance test of welding metal and sulfuric acid and a survey of welding workability. The test piece used for the corrosion resistance test was prepared as shown in FIG. That is, in order not to be affected by the base material component, a build-
[0041]
In the corrosion test, an immersion corrosion test was performed for 24 hours with 20% sulfuric acid at 40 ° C. and for 24 hours with 10% hydrochloric acid at 80 ° C., and the average corrosion weight loss of each of the four test pieces was determined. 2 · hr) or less, 2.5 mg / (cm 2 · hr) is slightly inferior, and 11 mg / (cm 2 · hr) or more is inferior.
[0042]
In the investigation of welding workability, mild steel with a plate thickness of 12 mm, a width of 100 mm, and a length of 450 mm is assembled into a T shape, and the horizontal fillet is welded at a current of 270 A and a voltage of 27 V, and in a vertical posture, a welding operation is performed at a current of 220 A and a voltage of 20 V. The arc state, slag state, the amount of spatter, and the bead shape were investigated. In the determination, the evaluation in each posture was comprehensively determined, and “good” was evaluated as “good”, “slightly inferior” as “△”, and “poor” as “poor”.
[0043]
The test results are shown in Table 4.
[0044]
[Table 4]
Wire No. 1- No. 3, no. 5, no. 8-No. 10, no. 14- No. No. 16 is an example of the present invention. Since each condition is appropriate, the corrosion weight loss with sulfuric acid resistance and hydrochloric acid resistance is small, and the result is good, and the welding workability is satisfactory.
[0046]
Wire No. 17-No. No. 24 is a comparative example. 17 and No. No. 18 is a case where the average particle size of Sb is not appropriate. No. 17 had a small average particle size of Sb in the flux, so that the viscosity of the slag was lowered and the bead was liable to be drooped by vertical welding. No. In No. 18, the average particle size of Sb was too large and Ni was low, so the corrosion resistance was slightly worse.
[0047]
No. No. 19 has poor welding workability due to a small amount of Si, and because of too much S, the corrosion resistance with sulfuric acid was significantly deteriorated. Moreover, since there is also much Cu, mechanical strength became too large.
[0048]
No. No. 20 had a large amount of Mn, so the viscosity of the slag was lowered, the bead was liable to be drooped by vertical welding, and the welding workability was deteriorated. In addition, since Sb was insufficient, sulfuric acid resistance and hydrochloric acid resistance were extremely poor.
[0049]
No. No. 21 had low C and low arc force, and had poor welding workability.
[0050]
No. No. 22 was poor in sulfuric acid resistance and hydrochloric acid resistance because Sb was not added.
[0051]
No. In No. 23, since there was much Si, arc force became strong and spatter increased, and since P was excessive, sulfuric acid resistance and hydrochloric acid resistance deteriorated.
[0052]
No. No. 24 had good corrosion resistance, but the amount of Sb added was large, the arc state deteriorated, and welding workability was considerably deteriorated.
[0053]
【The invention's effect】
As described above, according to the welding flux-cored wire of the present invention, a weld metal having extremely excellent sulfuric acid resistance and hydrochloric acid resistance is obtained, and a welding flux-cored wire having good welding workability is provided. Became possible.
[Brief description of the drawings]
FIG. 1A is a diagram showing a sampling procedure for a corrosion test piece.
(B) The figure which shows the aa 'cross section of (A).
[Explanation of symbols]
DESCRIPTION OF
Claims (5)
Ｃ：０．００５〜０．１５％、
Ｓｉ：０．１〜２％、
Ｍｎ：０．２〜３％、
Ｃｕ：０．１〜１％、
Ｎｉ：０．１〜０．６５％、
Ｓｂ：０．０１〜０．５％
を含有し、
かつ、Ｐ：０．０３％以下、
Ｓ：０．０３％以下に制限し、
残部がＦｅおよび不可避的不純物であることを特徴とする耐塩酸性および耐硫酸性に優れた低合金鋼のガスシールドアーク溶接用フラックス入りワイヤ。In the flux-cored wire formed by filling the steel outer shell with a filling flux, in one or both of the steel outer shell or the filling flux by mass% with respect to the total mass of the wire,
C: 0.005 to 0.15%,
Si: 0.1 to 2%,
Mn: 0.2-3%,
Cu: 0.1 to 1%,
Ni: 0.1 to 0.65%,
Sb: 0.01 to 0.5%
Containing
And P: 0.03% or less,
S: limited to 0.03% or less,
A flux-cored wire for gas shielded arc welding of low alloy steel excellent in hydrochloric acid resistance and sulfuric acid resistance, wherein the balance is Fe and inevitable impurities.
Ｍｏ：０．０１〜０．５％
を含有することを特徴とする請求項１または２に記載の耐塩酸性および耐硫酸性に優れた低合金鋼のガスシールドアーク溶接用フラックス入りワイヤ。In one or both of the steel outer shell or the filling flux in mass% with respect to the total mass of the wire,
Mo: 0.01 to 0.5%
The flux-cored wire for gas shielded arc welding of low alloy steel excellent in hydrochloric acid resistance and sulfuric acid resistance according to claim 1 or 2, characterized by comprising:
金属酸化物：３０〜６５％ 、
鉄粉 ：１０〜３０％を含有することを特徴とする請求項１〜３のいずれか１項に記載の耐塩酸性および耐硫酸性に優れた低合金鋼のガスシールドアーク溶接用フラックス入りワイヤ。In mass% with respect to the total mass of the filling flux, in the filling flux,
Metal oxide: 30 to 65%
Iron powder: 10-30% is contained, The flux cored wire for gas shield arc welding of the low alloy steel excellent in hydrochloric acid resistance and sulfuric acid resistance of any one of Claims 1-3 characterized by the above-mentioned.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2002255345A JP3892781B2 (en) | 2002-08-30 | 2002-08-30 | Flux-cored wire for gas shielded arc welding of low alloy steel with excellent hydrochloric acid resistance and sulfuric acid resistance |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2002255345A JP3892781B2 (en) | 2002-08-30 | 2002-08-30 | Flux-cored wire for gas shielded arc welding of low alloy steel with excellent hydrochloric acid resistance and sulfuric acid resistance |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JP2004090042A JP2004090042A (en) | 2004-03-25 |
| JP3892781B2 true JP3892781B2 (en) | 2007-03-14 |
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| Application Number | Title | Priority Date | Filing Date |
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| JP2002255345A Expired - Lifetime JP3892781B2 (en) | 2002-08-30 | 2002-08-30 | Flux-cored wire for gas shielded arc welding of low alloy steel with excellent hydrochloric acid resistance and sulfuric acid resistance |
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Families Citing this family (8)
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|---|---|---|---|---|
| JP4874064B2 (en) * | 2006-11-21 | 2012-02-08 | 新日本製鐵株式会社 | Non-consumable electrode type metal cored wire for welding |
| JP2008126279A (en) * | 2006-11-21 | 2008-06-05 | Nippon Steel Corp | Flux-cored wire for gas shielded arc welding |
| JP5345770B2 (en) * | 2007-07-27 | 2013-11-20 | 株式会社神戸製鋼所 | Titanya flux cored wire |
| JP5717688B2 (en) * | 2012-04-25 | 2015-05-13 | 日鐵住金溶接工業株式会社 | Flux-cored wire for horizontal fillet gas shielded arc welding of crude oil tank steel |
| KR101510562B1 (en) | 2013-12-06 | 2015-04-08 | 주식회사 포스코 | Flux cored arc welding materials in order to develop corrosion resistance |
| WO2015083877A1 (en) * | 2013-12-06 | 2015-06-11 | 주식회사 포스코 | High corrosion resistance welded joint and welding material therefor |
| JP7007253B2 (en) * | 2018-11-22 | 2022-02-10 | 株式会社神戸製鋼所 | Flux-filled wire for gas shielded arc welding |
| CN109877487A (en) * | 2019-03-19 | 2019-06-14 | 首钢集团有限公司 | A kind of high impact toughness solid welding wire and preparation method thereof with resistance to acid liquid corrosion |
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2002
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