JP3822181B2

JP3822181B2 - Low hydrogen type welding rod

Info

Publication number: JP3822181B2
Application number: JP2003103675A
Authority: JP
Inventors: 健太郎岩立; 正夫梅木
Original assignee: 日鐵住金溶接工業株式会社
Priority date: 2003-04-08
Filing date: 2003-04-08
Publication date: 2006-09-13
Anticipated expiration: 2023-04-08
Also published as: JP2004306094A

Description

【０００１】
【発明の属する技術分野】
本発明は、造船、橋梁および建築等の構造物で仮付け溶接に用いられる低水素系溶接棒に係わり、良好な溶接作業性を維持しつつ、電撃防止装置付き溶接機においても優れた再アーク性と電撃防止装置なしの溶接機における耐サイドアーク性が得られる低水素系仮付け用溶接棒（以下、仮付け棒と称する。）に関するものである。
【０００２】
【従来の技術】
仮付け棒は、耐割れ性や機械的性質が優れていることから、高張力鋼や低温用鋼を使用する重要構造物や厚板を使用する大型構造物などの仮付け溶接に多く適用されている。断続的に溶接を行う仮付け溶接は溶接途中でアークを中断させ再度アークを発生させる場合、被覆筒を砕いて心線を鋼板に接触させてアークを発生させるが、被覆が部分的に欠けていると溶着金属にピット、ブローホール等の溶接欠陥が発生し易いので、溶接により形成された被覆筒を鋼板に軽く接触させることでアークが容易に発生することが望ましい。
【０００３】
また、通常の溶接機は無負荷電圧が約６０〜９０Ｖであるが、感電防止のために電撃防止装置が使用されている。この電撃防止装置はアークの発生と共に電撃防止が解除され、アーク発生から約１秒で約６０〜９０Ｖから約１０〜２５Ｖに下げる役割がある。しかし、電撃防止装置は安全性のため無負荷電圧が低いので再アークの発生が非常に困難である。また再アーク性のみを考慮して鉄粉等の導電性の高い原材料に頼ると、無負荷電圧が高い通常の溶接機を使用した場合に、溶接棒の被覆部からアークが発生し易いことが知られている。
【０００４】
このような状況に対し、仮付け棒の再アーク性を良好にするため被覆筒の導電性向上を目的に被覆剤中の鉄粉に関する提案が種々されている。例えば、鉄粉の平均粒径、比表面積を限定し、この鉄粉を特定量被覆剤に添加をすることにより再アーク性を向上する技術があるが（例えば、特許文献１参照）、電撃防止装置のない溶接機では溶接棒の被覆部からアークが発生する。すなわち、耐サイドアーク性が劣化してしまう。また、被覆剤中に金属炭酸塩、金属弗化物、鉄粉、セルロース、デキストリンの添加量と、更にセルロースとデキストリンの合計を規定することによって電撃防止装置付き溶接機での再アーク性を向上する技術があるが（例えば、特許文献２参照）、デキストリンはセルロースに比べると炭化温度が低く炭化物が多く形成されるため再アーク性は大幅に改善できるが、被覆の導電性が劣ることから耐棒焼性が劣化して、アーク状態の劣化、ビード形状不良およびピットやブロホールが生じる。また、心線の比抵抗、或いは心線と溶接棒ホルダーとの接触抵抗を限定することによって被覆剤の金属粉添加量にかかわりなく再アーク性を向上できる技術がある（例えば、特許文献３）。しかし、その効果は薄く、耐サイドアーク性は劣るので再アーク性と耐サイドアーク性両方の改善とはならない。
【０００５】
このように従来の仮付け棒では再アーク性が良好で、かつ耐サイドアーク性をも満足することは非常に困難であった。
【０００６】
【特許文献１】
特開平１１−２２６７７９号公報
【特許文献２】
特開２０００−１０７８８９号公報
【特許文献３】
特開平０９−１５０２９号公報
【特許文献４】
特開平１０−２５８１号公報
【特許文献５】
特開平１０−２９６４８５号公報
【０００７】
【発明が解決しようとする課題】
本発明は、溶接作業性が良好で、電撃防止装置付き溶接機での再アーク性が極めて良好であり、かつ電撃防止装置のない溶接機での耐サイドアーク性をも満足する仮付け棒を提供することを目的とする。
【０００８】
【課題を解決するための手段】
本発明者は、優れた再アーク性と耐サイドアーク性を同時に満足させるためには、鋼心線と被覆筒との絶縁抵抗及び鋼心線と被覆剤との絶縁抵抗とを制御することが重要であることを知見し、本発明を完成した。
【０００９】
【課題を解決するための手段】
本発明の要旨は、以下のとおりである。
質量％で、金属炭酸塩を２０〜５０％、金属弗化物を０．５〜３．５％、鉄粉を２２〜５５％、白樺粉を含む有機物を０．５〜３．５％含有する被覆剤を鋼心線に被覆率を３０〜４０％として塗布し、更に鋼心線と被覆筒先端との絶縁抵抗が０．０２ＭΩ以下、鋼心線と被覆剤との絶縁抵抗が０．０１〜０．２０ＭΩ以下であることを特徴とする低水素系仮付け用溶接棒。
【００１１】
【発明の実施の形態】
本発明者らは、優れた再アーク性が得られ、かつ耐サイドアーク性が良好な仮付け溶接棒について鋭意研究を行った。その結果、再アーク性は、鋼心線と被覆筒との絶縁抵抗（以下、絶縁抵抗Ｃと称す。）に大きく依存し、また耐サイドアーク性については鋼心線と被覆剤との絶縁抵抗（以下、絶縁抵抗Ｆと称す。）に大きく依存することから再アーク性と耐サイドアーク性を同時に満足させるには、これらの絶縁抵抗Ｃ、Ｆの値が極めて重要な影響を与えることを見出した。
【００１２】
絶縁抵抗Ｃは０．０２ＭΩ以下で低いほど再アーク性が良好であるが、０．０２ＭΩを超えると電撃防止装置付きの溶接機を用いたときの再アーク性が劣ることがわかった。また絶縁抵抗Ｆが０．０１〜０．２０ＭΩであると、電撃防止装置なしの溶接機を使用したときでも被覆からスパークする心配はなく、耐サイドアーク性は良好となる。しかし、絶縁抵抗Ｆの値が０．２０ＭΩを超えると耐サイドアーク性は良好であるが、被覆の導電性が劣り耐棒焼け性が劣化して、アーク状態の劣化、ビード形状不良およびピットやブロホールが生じるようになる。また絶縁抵抗Ｆの値が０．０１ＭΩ未満であると耐サイドアーク性が劣化する。
【００１３】
なお、本発明にいう絶縁抵抗Ｃの測定方法を図１に示す。まず、鋼板上で溶接棒１の鋼心線径２．６ｍｍの場合１１０Ａ、３．２ｍｍの場合１５０Ａ、４．０ｍｍの場合２００Ａ、５．０ｍｍの場合２６０Ａの溶接電流で約１０秒間溶接を行い、溶接棒１先端に被覆筒２を作る。次いで、前記溶接で生じた被覆筒２を角度９０°のＬ形の銅板３に対して４５℃の角度で当接する。そして溶接棒１のホルダー側に絶縁抵抗計６からのアース端子４を接続し、Ｌ形の銅板３にライン端子５を接続する。絶縁抵抗計６から負荷電圧を５００Ｖかけて絶縁抵抗Ｃの絶対値を計測する。
【００１４】
また、絶縁抵抗Ｆの測定方法については図２に示す。測定治具は長手方向に凹部分を有する銅板７に薄く延ばしたスチールウール８を凹部分に密着させて、そのスチールウール８の上に溶接棒１をセットする。次に、溶接棒１を絶縁テープ９で固定し、溶接棒１のホルダー側に絶縁抵抗計６からのアース端子４を接続し、銅板７にライン端子５を接続する。絶縁抵抗計６から負荷電圧を５００Ｖかけて絶縁抵抗Ｆの絶対値を計測する。
【００１５】
また、絶縁抵抗Ｃ、絶縁抵抗Ｆは使用原材料の物性から個々の添加量によって大きく変化することから使用原材料の添加量を限定する必要があり、また、被覆率も絶縁抵抗Ｃ、Ｆへ影響するため限定する必要がある。
【００１６】
被覆筒の導電性を高めるため被覆剤中に鉄粉を含有させることを基本とするが、鉄粉を５５質量％（以下、％と称す。）超えて含有させると絶縁抵抗Ｃが低くなり再アーク性は改善されるが、絶縁抵抗Ｆも低くなるため耐サイドアーク性は劣化する。また、アークの吹き付けが弱くなり溶け込み深さが浅くなる。鉄粉の添加量が２２％未満であると絶縁抵抗Ｃが高くなり電撃防止装置付き溶接機を用いたときの再アーク性が劣化する。したがって鉄粉添加量は２２〜５５％であることが必要である。
【００１７】
次に再アーク性および耐サイドアーク性を向上させるための手段として白樺粉やセルロース等の有機物の添加が有効であり、これらは絶縁物であるので絶縁抵抗Ｆが高くなり耐サイドアーク性を向上させる。また溶接時のアーク熱により被覆筒とその近傍で燃焼し炭化物を生成するため絶縁抵抗Ｃが低くなり再アーク性も向上する。しかし有機物が３．５％を超えると拡散性水素量が増加し低水素系溶接棒として成り立たなくなり、またアークの吹き付けが強くなりすぎスパッタ発生量が多くなる。０．５％未満であると再アーク性および耐サイドアーク性ともに向上させることができない。
【００１８】
なお、前記有機物に白樺粉を用いることにより、繊維が太くかつ長いので炭化物の生成量を調整して絶縁抵抗Ｆが高くなり耐サイドアーク性をさらに良好にする。そして、３．５％の範囲で単独または他の有機物と併用して用いることができる。
【００１９】
また、金属炭酸塩、金属弗化物等の非金属物が多いほど、絶縁抵抗Ｃが高くなるが、諸溶接作業性を満足させるには欠かせない原材料である。
【００２０】
金属炭酸塩は、アーク中で分解しＣＯ₂ガスを発生して溶着金属や溶融スラグを大気から保護し、窒素、酸素、水素の侵入を阻害すると共にアーク力を確保し、スラグの流動性、粘性を調整するもので２０〜５０％必要である。金属炭酸塩が２０％未満であるとガス発生量が少なく大気中の水素等を巻込みやすく拡散性水素量が増加し、５０％を超えるとアークが強くなりすぎスパッタ発生量が増加する。金属炭酸塩としては、例えば炭酸石灰、炭酸バリウム、炭酸マグネシウムや炭酸ナトリウム等を用いることができる。
【００２１】
金属弗化物は、スラグの溶融点を下げ、流動性の良好なスラグを得るため０．５〜３．５％必要である。０．５％未満では、満足なスラグの流動性が得られず、スラグ被包性が劣ることからビード形状が劣化し、３．５％を超えると流動性が過度に良くなり、スラグ被包性が劣りビード形状が劣化する。金属弗化物としては、例えば、蛍石、永晶石や弗化ソーダを用いることができる。
【００２２】
更に、被覆剤の被覆率も絶縁抵抗Ｃ、Ｆに対し重要になる。被覆率が３０％未満であると絶縁抵抗Ｆが低くなり耐サイドアーク性が劣化し、また、鋼心線を含めた金属分が多くなることからスラグ剤やアーク安定剤等が不足しビード形状が劣化する。被覆率が４５％を超えると被覆筒先端と心線部の距離が長くなり絶縁抵抗Ｃが高くなるため再アーク性が劣化することになる。
【００２３】
なお、本発明の仮付け棒は、前記被覆剤の他に機械的性質および溶接作業性を考慮してフェロシリコン、金属マンガンおよびフェロチタンなどの脱酸剤を２０％以下、ルチールおよび珪灰石などのアーク安定剤を５％以下、珪砂、長石および酸化マグネシウムなどのスラグ生成剤を３％以下、また固着剤中の珪酸カリウムおよび珪酸ナトリウムなどを８％以下の範囲で含むことができる。
【００２４】
【実施例】
次に実施例により本発明の効果をさらに詳細に述べる。
【００２５】
表１に示す各種組成の被覆剤を、直径４．０ｍｍ、長さ４００ｍｍのＪＩＳＧ３５２３ＳＷＹ１１の鋼心線に塗装した後、最高温度４００℃で乾燥して２０種類の溶接棒を試作し、各種試験を実施した。
【００２６】
【表１】

【００２７】
絶縁抵抗Ｃの測定は前述の図１に示した方法で各試作溶接棒１本に付き繰り返し４回、合計２０本測定した。
【００２８】
また、絶縁抵抗Ｆの測定は前述の図２に示した方法で各試作溶接棒１本に付き繰り返し４回、合計２０本測定した。それらの測定結果を表１に示す。
【００２９】
絶縁抵抗Ｃを測定した各溶接棒を、電撃防止装置の付いた溶接機を用いて再アーク性を調査した。試験方法は、鋼板（板厚９ｍｍ，４９０Ｎ／ｍｍ²級）をＴ型に組んだ試験体のすみ肉部へ軽く接触させ、溶接電流２００Ａで直ちにアークが発生したものを合格とし、合格本数が８割の１６本以上を○とし、１２〜１５本を△、１１本以下を×とした。
【００３０】
また、絶縁抵抗Ｆを測定した各溶接棒を、電撃防止装置のない溶接機を用いて耐サイドアーク性を調査した。再アーク性を調査した試験板と同一の試験板の角部分へ被覆剤部を軽く接触させ、アークが発生しないものを合格とし、合格本数が２０本を○とし、１本でも被覆からアークが発生したものを×とした。それらの試験結果を表２にまとめて示す。
【００３１】
次に溶接作業性の調査は、前述の鋼板をＴ型に組み、溶接電流２００Ａでの水平すみ肉および立向下進で溶接をしてアーク状態、スラグ状態、ビード形状、耐棒焼け性などを調査した。その判定は、各溶接姿勢の総合判定とし、良好なものは○印、劣るものを×印とした。これらの調査結果も表２に示す。
【００３２】
【表２】

【００３３】
表２中溶接棒Ｎｏ．１〜１０が本発明例、溶接棒Ｎｏ．１１〜２０は比較例である。本発明である溶接棒Ｎｏ．１〜１０は、金属炭酸塩、金属弗化物、鉄粉および有機物の量が適正で、鋼心線への被覆率、絶縁抵抗Ｃおよび絶縁抵抗Ｆも本発明の要件を満足しており、電撃防止装置付き溶接機での再アーク性および電撃防止装置のない溶接機での耐サイドアーク性も良好で、かつ溶接作業性も良好であり、極めて満足な結果であった。
【００３４】
比較例中の溶接棒Ｎｏ．１１は、被覆剤中の金属炭酸塩が多いのでアークが強くなりスパッタが多発した。また、被覆率が高いので絶縁抵抗Ｃが高く再アーク性が劣化し、さらに絶縁抵抗Ｆも高いので耐棒焼け性が劣化した。
【００３５】
溶接棒Ｎｏ．１２は、被覆剤中の金属炭酸塩が少ないのでガス発生量が不足し別途実施した拡散性水素量を測定した結果、拡散性水素量が多かった。また、被覆率が低いので絶縁抵抗Ｆが低くなり耐サイドアーク性が劣化した。更に鋼心線を含めた金属分が多くスラグ生成量が少なくなったのでビード形状が劣化した。
【００３６】
溶接棒Ｎｏ．１３は、被覆剤中の金属弗化物が多いのでスラグ流動性が過度に良くなりスラグ被包性が悪くなってビード形状が劣化した。また、被覆剤中の有機物が多いのでアークの吹き付けが強くなりすぎスパッタ発生量が多くなった。また、別途実施した拡散性水素量を測定した結果、拡散性水素量が多かった。
【００３７】
溶接棒Ｎｏ．１４は、有機物に白樺粉を含んでいないのでスラグ被包性が悪くなってビード形状が劣化した。また、被覆剤中の有機物が少ないので絶縁抵抗Ｃが高くなり再アーク性がやや劣り、絶縁抵抗Ｆが低くなり耐サイドアーク性も劣化した。
【００３８】
溶接棒Ｎｏ．１５は、被覆剤中の鉄粉が多いので絶縁抵抗Ｆが低くなりサイドアーク性が劣化し、アーク吹き付けも弱くなり溶け込み深さが浅くなった。また、被覆剤中の金属弗化物が多いのでビード形状が劣化した。
【００３９】
溶接棒Ｎｏ．１６は、被覆剤中の鉄粉が少ないので絶縁抵抗Ｃが高くなり再アーク性が劣化した。また、被覆剤中の金属弗化物が少ないのでビード形状が劣化した。
【００４０】
溶接棒Ｎｏ．１７は、被覆剤中の金属炭酸塩が多いのでアークが強くなりスパッタ発生量が多かった。
【００４１】
溶接棒Ｎｏ．１８は、被覆剤中の有機物が少ないので絶縁抵抗Ｃが高く再アーク性が劣化した。更に絶縁抵抗Ｆが低く耐サイドアーク性も劣化した。
【００４２】
溶接棒Ｎｏ．１９は、被覆剤中の鉄粉が多いので絶縁抵抗Ｆが低くなりサイドアーク性が劣化し、アーク吹き付けも弱くなり溶け込み深さが浅くなった。
【００４３】
溶接棒Ｎｏ．２０は、被覆剤中の鉄粉が少ないので絶縁抵抗Ｃが高くなり再アーク性が劣化した。
【００４４】
【発明の効果】
以上詳述したように、本発明の低水素系仮付け用溶接棒によれば溶接作業性を満足しつつ、電撃防止装置の付いた溶接機においても再アーク性が優れ、かつ無負荷電圧の高い溶接機においても良好な耐サイドアーク性が得られるので、仮付け溶接の作業能率の向上に大きく貢献できる。
【図面の簡単な説明】
【図１】鋼心線と被覆筒先端との絶縁抵抗Ｃを測定する方法の説明図である。
【図２】鋼心線と被覆剤との絶縁抵抗Ｆを測定する方法の説明図である。
【符号の説明】
１溶接棒
２被覆筒
３Ｌ形の銅板
４アース端子
５ライン端子
６絶縁抵抗計
７銅板
８スチールウール
９絶縁テープ[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a low hydrogen welding rod used for tack welding in structures such as shipbuilding, bridges, and buildings, and maintains excellent welding workability while also achieving excellent rearcing in a welding machine with an electric shock prevention device. The present invention relates to a low hydrogen-based tacking welding rod (hereinafter, referred to as a tacking rod) that can provide side arc resistance in a welding machine without electrical properties and an electric shock prevention device.
[0002]
[Prior art]
Temporary sticks have excellent crack resistance and mechanical properties, so they are often used for tack welding of important structures using high-strength steel and low-temperature steel and large structures using thick plates. ing. In tack welding where intermittent welding is performed, when the arc is interrupted and the arc is generated again during welding, the sheath is broken and the core wire is brought into contact with the steel sheet to generate the arc, but the coating is partially missing. If so, welding defects such as pits and blowholes are likely to occur in the weld metal. Therefore, it is desirable that the arc is easily generated by lightly contacting the coated tube formed by welding with the steel plate.
[0003]
Further, a normal welding machine has a no-load voltage of about 60 to 90 V, but an electric shock prevention device is used to prevent an electric shock. This electric shock prevention device releases the electric shock prevention as the arc is generated, and has a role of reducing the voltage from about 60 to 90 V to about 10 to 25 V in about 1 second after the arc is generated. However, since the no-load voltage is low for safety, the electric shock prevention device is very difficult to generate a re-arc. In addition, if only re-arcing properties are considered and depend on highly conductive raw materials such as iron powder, arcs are likely to be generated from the coating of the welding rod when using a normal welding machine with high no-load voltage. Are known.
[0004]
In order to improve the re-arcing property of the tacking rod, various proposals relating to iron powder in the coating have been made for the purpose of improving the conductivity of the coated cylinder. For example, there is a technique for improving the re-arcing property by limiting the average particle size and specific surface area of iron powder and adding a specific amount of this iron powder to a coating agent (see, for example, Patent Document 1). In a welding machine without a device, an arc is generated from the covering portion of the welding rod. That is, the side arc resistance is deteriorated. In addition, by specifying the amount of metal carbonate, metal fluoride, iron powder, cellulose, dextrin added to the coating material, and the total amount of cellulose and dextrin, the re-arcing performance in a welding machine equipped with an electric shock prevention device is improved. Although there is a technique (see, for example, Patent Document 2), dextrin has a lower carbonization temperature and a larger amount of carbide is formed than cellulose, so that the rearcability can be greatly improved. The sinterability deteriorates, resulting in deterioration of the arc state, bead shape defects, pits and blowholes. In addition, there is a technique that can improve the re-arcability regardless of the amount of metal powder added to the coating material by limiting the specific resistance of the core wire or the contact resistance between the core wire and the welding rod holder (for example, Patent Document 3). . However, since the effect is thin and the side arc resistance is inferior, it does not improve both the re-arc resistance and the side arc resistance.
[0005]
Thus, it has been very difficult for the conventional tacking rods to have good re-arcing properties and to satisfy side arc resistance.
[0006]
[Patent Document 1]
Japanese Patent Laid-Open No. 11-226779 [Patent Document 2]
JP 2000-107889 A [Patent Document 3]
Japanese Patent Laid-Open No. 09-15029 [Patent Document 4]
Japanese Patent Laid-Open No. 10-2581 [Patent Document 5]
Japanese Patent Laid-Open No. 10-296485 [0007]
[Problems to be solved by the invention]
The present invention provides a tacking rod having good welding workability, extremely good re-arcing in a welding machine with an electric shock prevention device, and satisfying side arc resistance in a welding machine without an electric shock prevention device. The purpose is to provide.
[0008]
[Means for Solving the Problems]
The present inventor can control the insulation resistance between the steel core wire and the covering tube and the insulation resistance between the steel core wire and the coating agent in order to satisfy both the excellent re-arcing property and the side arc resistance simultaneously. As a result, the present invention was completed.
[0009]
[Means for Solving the Problems]
The gist of the present invention is as follows.
20% to 50% by weight of metal carbonate, 0.5 to 3.5% of metal fluoride, 22 to 55% of iron powder, and 0.5 to 3.5% of organic matter including white powder. The coating agent is applied to the steel core wire at a coverage of 30 to 40%, and the insulation resistance between the steel core wire and the coating tube tip is 0.02 MΩ or less, and the insulation resistance between the steel core wire and the coating agent is 0.01. A welding rod for low hydrogen temporary tacking, characterized in that it is ˜0.20 MΩ or less.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
The inventors of the present invention have intensively studied a tack welding rod that has excellent re-arcing properties and good side arc resistance. As a result, the re-arcing property greatly depends on the insulation resistance between the steel core wire and the coated cylinder (hereinafter referred to as insulation resistance C), and the side arc resistance is the insulation resistance between the steel core wire and the coating agent. (Hereinafter referred to as the insulation resistance F), it is found that the values of these insulation resistances C and F have an extremely important influence in order to satisfy the re-arcing property and the side arc resistance at the same time. It was.
[0012]
The lower the insulation resistance C is 0.02 MΩ or lower, the better the re-arcing property. However, when it exceeds 0.02 MΩ, it was found that the re-arcing property is inferior when using a welding machine with an electric shock prevention device. Further, when the insulation resistance F is 0.01 to 0.20 MΩ, there is no fear of sparking from the coating even when a welding machine without an electric shock prevention device is used, and the side arc resistance is good. However, if the value of the insulation resistance F exceeds 0.20 MΩ, the side arc resistance is good, but the conductivity of the coating is inferior and the bar burn resistance is deteriorated. Blowholes are generated. Further, when the value of the insulation resistance F is less than 0.01 MΩ, the side arc resistance is deteriorated.
[0013]
In addition, the measuring method of the insulation resistance C said to this invention is shown in FIG. First, welding is performed for about 10 seconds on a steel plate with a welding current of 110A for a steel core wire diameter of 2.6 mm, 150 A for 3.2 mm, 200 A for 4.0 mm, 200 A for 4.0 mm, and 260 A for 5.0 mm. The covering tube 2 is made at the tip of the welding rod 1. Next, the coated cylinder 2 generated by the welding is brought into contact with the L-shaped copper plate 3 having an angle of 90 ° at an angle of 45 ° C. Then, the ground terminal 4 from the insulation resistance meter 6 is connected to the holder side of the welding rod 1, and the line terminal 5 is connected to the L-shaped copper plate 3. The absolute value of the insulation resistance C is measured by applying a load voltage of 500 V from the insulation resistance meter 6.
[0014]
A method for measuring the insulation resistance F is shown in FIG. The measuring jig has a steel wool 8 that is thinly extended on a copper plate 7 having a concave portion in the longitudinal direction, and the welding rod 1 is set on the steel wool 8. Next, the welding rod 1 is fixed with an insulating tape 9, the ground terminal 4 from the insulation resistance meter 6 is connected to the holder side of the welding rod 1, and the line terminal 5 is connected to the copper plate 7. The absolute value of the insulation resistance F is measured by applying a load voltage of 500 V from the insulation resistance meter 6.
[0015]
In addition, since the insulation resistance C and the insulation resistance F vary greatly depending on the amount of each material added due to the physical properties of the materials used, it is necessary to limit the amount of materials used, and the coverage also affects the insulation resistances C and F. Therefore, it is necessary to limit.
[0016]
In order to increase the conductivity of the coated cylinder, iron powder is basically contained in the coating agent. However, if the iron powder exceeds 55% by mass (hereinafter referred to as “%”), the insulation resistance C is lowered. Although the arc property is improved, the side arc resistance is deteriorated because the insulation resistance F is also lowered. Moreover, the arc spray becomes weak and the penetration depth becomes shallow. If the amount of iron powder added is less than 22%, the insulation resistance C increases, and the re-arcing property when using a welding machine with an electric shock prevention device deteriorates. Therefore, the iron powder addition amount needs to be 22 to 55%.
[0017]
Next, the addition of organic substances such as white powder and cellulose is effective as a means for improving the re-arcing property and side arc resistance. Since these are insulators, the insulation resistance F is increased and the side arc resistance is improved. Let In addition, since the arc heat during welding burns in the vicinity of the coated cylinder and generates carbides, the insulation resistance C is lowered and the re-arcing property is improved. However, if the organic content exceeds 3.5%, the amount of diffusible hydrogen increases, and it cannot be realized as a low hydrogen welding rod, and the arc spray becomes too strong and the amount of spatter generated increases. If it is less than 0.5%, neither the re-arcing property nor the side arc resistance can be improved.
[0018]
By using birch powder as the organic material, since the fibers are thick and long, the generation amount of carbide is adjusted, the insulation resistance F is increased, and the side arc resistance is further improved. And it can be used alone or in combination with other organic substances in the range of 3.5%.
[0019]
In addition, the more non-metallic materials such as metal carbonates and metal fluorides, the higher the insulation resistance C, but it is an indispensable raw material for satisfying various workability.
[0020]
Metal carbonate decomposes in the arc and generates CO ₂ gas to protect the deposited metal and molten slag from the atmosphere, while preventing the intrusion of nitrogen, oxygen and hydrogen and ensuring the arc force, slag fluidity, It is necessary to adjust the viscosity and needs 20 to 50%. If the amount of metal carbonate is less than 20%, the amount of gas generated is small and hydrogen in the atmosphere is easily involved, and the amount of diffusible hydrogen increases. If it exceeds 50%, the arc becomes too strong and the amount of spatter generated increases. As the metal carbonate, for example, lime carbonate, barium carbonate, magnesium carbonate, sodium carbonate or the like can be used.
[0021]
The metal fluoride is required to be 0.5 to 3.5% in order to lower the melting point of slag and obtain slag having good fluidity. If it is less than 0.5%, satisfactory slag fluidity cannot be obtained, and slag encapsulation is inferior, so that the bead shape deteriorates. If it exceeds 3.5%, fluidity becomes excessively good, and slag encapsulation Inferior properties and bead shape deteriorate. As the metal fluoride, for example, fluorite, perovskite or sodium fluoride can be used.
[0022]
Furthermore, the coverage of the coating material is also important for the insulation resistances C and F. If the coverage is less than 30%, the insulation resistance F is lowered, the side arc resistance is deteriorated, and the metal content including the steel core wire is increased. Deteriorates. If the coverage exceeds 45%, the distance between the tip of the coated cylinder and the core portion becomes longer and the insulation resistance C becomes higher, so that the re-arcing property is deteriorated.
[0023]
The tacking rod of the present invention has a deoxidizing agent such as ferrosilicon, manganese metal, and ferrotitanium in an amount of 20% or less, rutile, wollastonite, and the like in consideration of mechanical properties and welding workability in addition to the coating agent. 5% or less of the arc stabilizer, 3% or less of slag forming agents such as silica sand, feldspar and magnesium oxide, and 8% or less of potassium silicate and sodium silicate in the fixing agent.
[0024]
【Example】
Next, the effects of the present invention will be described in more detail by way of examples.
[0025]
After coating the coating composition of various compositions shown in Table 1 on a steel core wire of JISG3523 SWY11 having a diameter of 4.0 mm and a length of 400 mm, it was dried at a maximum temperature of 400 ° C. to produce 20 types of welding rods, and various tests Carried out.
[0026]
[Table 1]

[0027]
The measurement of the insulation resistance C was repeated four times for each prototype welding rod by the method shown in FIG.
[0028]
In addition, the insulation resistance F was measured by repeating the method shown in FIG. The measurement results are shown in Table 1.
[0029]
Each welding rod for which the insulation resistance C was measured was examined for re-arcability using a welding machine equipped with an electric shock prevention device. The test method was to lightly contact a fillet part of a test piece assembled with a steel plate (9 mm thick, 490 N / mm ² grade) in a T shape, and immediately pass an arc that occurred at a welding current of 200 A. 80% of 16 or more were marked with ◯, 12-15 were marked with Δ, and 11 or less were marked with x.
[0030]
Further, the side arc resistance of each welding rod whose insulation resistance F was measured was investigated using a welding machine without an electric shock prevention device. The coating part is lightly brought into contact with the corner portion of the same test plate as the test plate for which the re-arc property was investigated, and a test piece that does not generate an arc is accepted. What occurred was marked as x. The test results are summarized in Table 2.
[0031]
Next, the welding workability is investigated by assembling the aforementioned steel plate into a T shape, welding with horizontal fillet at a welding current of 200A and vertical movement, arc state, slag state, bead shape, rod burn resistance, etc. investigated. The determination was made as a comprehensive determination of each welding posture, and a good one was marked with a circle, and an inferior one was marked with a x. These survey results are also shown in Table 2.
[0032]
[Table 2]

[0033]
In Table 2, the welding rod No. 1 to 10 are examples of the present invention, welding rod Nos. 11 to 20 are comparative examples. The welding rod no. In Nos. 1 to 10, the amount of metal carbonate, metal fluoride, iron powder, and organic matter is appropriate, and the coverage to the steel core wire, the insulation resistance C, and the insulation resistance F also satisfy the requirements of the present invention. The re-arcing property with the welding machine with the prevention device and the side arc resistance with the welding machine without the electric shock prevention device were good, and the welding workability was also good.
[0034]
The welding rod No. in the comparative example. No. 11 had many metal carbonates in the coating agent, so the arc became strong and spatter occurred frequently. Further, since the covering ratio is high, the insulation resistance C is high and the re-arcing property is deteriorated. Further, since the insulation resistance F is also high, the rod burn resistance is deteriorated.
[0035]
Welding rod no. No. 12 had a large amount of diffusible hydrogen as a result of measuring the amount of diffusible hydrogen carried out separately because the amount of metal carbonate in the coating was small and the amount of gas generated was insufficient. Moreover, since the coverage was low, the insulation resistance F was lowered and the side arc resistance was deteriorated. Furthermore, since the metal content including the steel core wire was large and the amount of slag generation was small, the bead shape deteriorated.
[0036]
Welding rod no. No. 13 had a large amount of metal fluoride in the coating agent, so that the slag fluidity was excessively improved, the slag encapsulation was deteriorated, and the bead shape was deteriorated. Moreover, since there are many organic substances in the coating material, the spraying of the arc becomes too strong and the amount of spatter generated increases. Moreover, as a result of measuring the amount of diffusible hydrogen carried out separately, the amount of diffusible hydrogen was large.
[0037]
Welding rod no. In No. 14, white organic powder was not included in the organic matter, so the slag encapsulation was deteriorated and the bead shape was deteriorated. Further, since the organic substance in the coating material is small, the insulation resistance C is increased and the re-arcing property is slightly inferior, the insulation resistance F is lowered and the side arc resistance is also deteriorated.
[0038]
Welding rod no. In No. 15, since there was a lot of iron powder in the coating agent, the insulation resistance F was lowered, the side arc property was deteriorated, the arc spraying was weakened, and the penetration depth was shallow. In addition, the bead shape deteriorated due to the large amount of metal fluoride in the coating agent.
[0039]
Welding rod no. In No. 16, since the iron powder in the coating material was small, the insulation resistance C was increased and the re-arcing property was deteriorated. In addition, the bead shape deteriorated because there was little metal fluoride in the coating agent.
[0040]
Welding rod no. No. 17 had a large amount of metal carbonate in the coating agent, so the arc became strong and the amount of spatter generated was large.
[0041]
Welding rod no. In No. 18, since the organic substance in the coating material was small, the insulation resistance C was high and the re-arcing property was deteriorated. Furthermore, the insulation resistance F was low and the side arc resistance was also deteriorated.
[0042]
Welding rod no. In No. 19, since there was a lot of iron powder in the coating agent, the insulation resistance F was lowered, the side arc property was deteriorated, the arc spraying was weakened, and the penetration depth was shallow.
[0043]
Welding rod no. In No. 20, since the iron powder in the coating material was small, the insulation resistance C was increased and the re-arcing property was deteriorated.
[0044]
【The invention's effect】
As described above in detail, according to the welding rod for low hydrogen-based tacking of the present invention, while satisfying welding workability, even in a welding machine equipped with an electric shock prevention device, excellent re-arcing property and no load voltage can be obtained. Even in a high welding machine, good side arc resistance can be obtained, which can greatly contribute to improvement of work efficiency of tack welding.
[Brief description of the drawings]
FIG. 1 is an explanatory diagram of a method for measuring an insulation resistance C between a steel core wire and a coated tube tip.
FIG. 2 is an explanatory diagram of a method for measuring an insulation resistance F between a steel core wire and a coating agent.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Welding rod 2 Coated cylinder 3 L-shaped copper plate 4 Ground terminal 5 Line terminal 6 Insulation resistance meter 7 Copper plate 8 Steel wool 9 Insulation tape

Claims

20% to 50% by weight of metal carbonate, 0.5 to 3.5% of metal fluoride, 22 to 55% of iron powder, and 0.5 to 3.5% of organic matter including white powder. The coating agent is applied to the steel core wire at a coverage of 30 to 40%, and the insulation resistance between the steel core wire and the coating tube tip is 0.02 MΩ or less, and the insulation resistance between the steel core wire and the coating agent is 0.01. A welding rod for low hydrogen temporary tacking, characterized in that it is ˜0.20 MΩ or less.