JP2004306094A

JP2004306094A - Low hydrogen-based tack welding rod

Info

Publication number: JP2004306094A
Application number: JP2003103675A
Authority: JP
Inventors: Kentaro Iwatate; 健太郎岩立; Masao Umeki; 正夫梅木
Original assignee: Nippon Steel and Sumikin Welding Co Ltd
Current assignee: Nippon Steel Welding and Engineering Co Ltd
Priority date: 2003-04-08
Filing date: 2003-04-08
Publication date: 2004-11-04
Anticipated expiration: 2023-04-08
Also published as: JP3822181B2

Abstract

<P>PROBLEM TO BE SOLVED: To provide a tack welding rod satisfactory in welding operability and extremely satisfactory in re-arc properties in a welding machine with a voltage reducing device, and also satisfactory in side arc resistance in a welding machine with no voltage reducing device. <P>SOLUTION: In the low hydrogen-based tack welding rod, a steel core wire is coated with a coating agent containing, by mass, 20 to 50% metal carbonate, 0.5 to 3.5% metal fluoride, 22 to 55% iron powder and 0.5 to 3.5% organic material in a coating ratio of 30 to 45%, further the insulating resistance between the steel core wire and the tip of a coating cylinder is ≤0.02 MΩ, and the insulating resistance between the steel core wire and the coating agent is 0.01 to 0.20 MΩ. The organic material preferably cotains white birch powder. <P>COPYRIGHT: (C)2005,JPO&NCIPI

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】
本発明の要旨は、以下のとおりである。
（１）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％、有機物を０．５〜３．５％含有する被覆剤を鋼心線に被覆率を３０〜４５％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であることを特徴とする低水素系仮付け用溶接棒。
【００１０】
（２）有機物が白樺粉を含むことを特徴とする上記（１）記載の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が高くなり耐再度アーク性をさらに良好にする。そして、３．５％以下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ＣＯ_２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／ｍｍ^２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]
TECHNICAL FIELD 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 while maintaining good welding workability, excellent re-arcing 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) which can obtain side arc resistance in a welding machine without an electric shock prevention device.
[0002]
[Prior art]
Since tacking rods have excellent cracking resistance and mechanical properties, they are often applied to tack welding of important structures using high-tensile steel or low-temperature steel or large structures using thick plates. ing. In the case of temporary welding, in which welding is performed intermittently, when the arc is interrupted during welding and an arc is generated again, the arc is generated by crushing the coating cylinder and bringing the core wire into contact with the steel plate, but the coating is partially missing. In such a case, welding defects such as pits and blowholes are likely to occur in the deposited metal. Therefore, it is desirable that an arc be easily generated by lightly contacting a coating tube formed by welding with a steel plate.
[0003]
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 electric shock. The electric shock prevention device releases the electric shock prevention when the arc is generated, and has a role of lowering the voltage from about 60 to 90 V to about 10 to 25 V in about 1 second after the arc is generated. However, the electric shock prevention device has a low no-load voltage for safety, so that it is very difficult to generate a re-arc. In addition, when relying on highly conductive raw materials such as iron powder in consideration of only the re-arc property, arcs are likely to be generated from the coating of the welding rod when using a normal welding machine with a high no-load voltage. Are known.
[0004]
Under such circumstances, various proposals have been made regarding iron powder in the coating agent for the purpose of improving the conductivity of the coating cylinder in order to improve the re-arcing property of the tacking rod. For example, there is a technique in which the average particle size and specific surface area of iron powder are limited, and the re-arc property is improved by adding the iron powder to a specific amount of a coating agent (for example, see Patent Document 1). In a welding machine without a device, an arc is generated from the coating portion of the welding rod. That is, the side arc resistance deteriorates. In addition, by defining the amount of metal carbonate, metal fluoride, iron powder, cellulose, and dextrin in the coating agent and the total amount of cellulose and dextrin, re-arcing in a welding machine 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 than cellulose, and a large amount of carbide is formed, so that re-arcing can be greatly improved. Deterioration of calcination causes deterioration of the arc state, defective bead shape, and pits and blowholes. Also, there is a technique capable of improving the re-arc property by limiting the specific resistance of the core wire or the contact resistance between the core wire and the welding rod holder regardless of the amount of metal powder added to the coating agent (for example, Patent Document 3). . However, the effect is thin and the side arc resistance is inferior, so that both the re-arc property and the side arc resistance cannot be improved.
[0005]
As described above, it is very difficult for the conventional tacking rod to have good re-arc properties and also satisfy the side arc resistance.
[0006]
[Patent Document 1]
JP-A-11-226779 [Patent Document 2]
JP 2000-107889 A [Patent Document 3]
Japanese Patent Application Laid-Open No. 09-15029 [Patent Document 4]
Japanese Patent Application Laid-Open No. 10-2581 [Patent Document 5]
JP 10-296485 A
[Problems to be solved by the invention]
The present invention provides a tacking rod that has good welding workability, extremely good re-arcability in a welding machine with an electric shock prevention device, and also satisfies 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 has to control the insulation resistance between the steel core wire and the cladding cylinder and the insulation resistance between the steel core wire and the coating agent in order to simultaneously satisfy the excellent re-arc property and the side arc resistance. The inventors have found that this is important and completed the present invention.
[0009]
The gist of the present invention is as follows.
(1) Coating containing 20 to 50% 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 by mass% The coating agent is applied to the steel core wire at a coverage of 30 to 45%, and the insulation resistance between the steel core wire and the tip of the coating tube is 0.02 MΩ or less, and the insulation resistance between the steel core wire and the coating agent is 0.01 to 45%. A low hydrogen-based tacking welding rod having a resistance of 0.20 MΩ.
[0010]
(2) The low hydrogen-based tacking welding rod according to the above (1), wherein the organic matter contains birch powder.
[0011]
BEST MODE FOR CARRYING OUT THE INVENTION
Means for Solving the Problems The present inventors have made intensive studies on tacked welding rods having excellent re-arc properties and good side arc resistance. As a result, the re-arc property greatly depends on the insulation resistance between the steel core wire and the sheathing cylinder (hereinafter, referred to as insulation resistance C), and the side arc resistance with respect to the insulation resistance between the steel core wire and the coating agent. (Hereinafter referred to as insulation resistance F), and found that the values of these insulation resistances C and F have extremely important effects in order to simultaneously satisfy the re-arc property and the side arc resistance. Was.
[0012]
It was found that the lower the insulation resistance C was 0.02 MΩ or lower, the better the re-arc property was. However, if the insulation resistance C exceeded 0.02 MΩ, the re-arc property was poor when a welding machine with an electric shock prevention device was used. Further, when the insulation resistance F is 0.01 to 0.20 MΩ, there is no risk 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, when 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 burning resistance is deteriorated. Bloholes begin to form. If the value of the insulation resistance F is less than 0.01 MΩ, the side arc resistance deteriorates.
[0013]
FIG. 1 shows a method for measuring the insulation resistance C according to the present invention. First, on a steel plate, welding is performed for about 10 seconds at a welding current of 110A when the core diameter of the welding rod 1 is 2.6mm, 150A when it is 3.2mm, 200A when it is 4.0mm, and 260A when it is 5.0mm. Then, a coating cylinder 2 is formed at the tip of the welding rod 1. Next, the coating tube 2 generated by the welding is brought into contact with the L-shaped copper plate 3 at 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]
FIG. 2 shows a method of measuring the insulation resistance F. The measuring jig sets a welding rod 1 on the steel wool 8 by closely contacting a thinly extended steel wool 8 with the copper plate 7 having a concave portion in the longitudinal direction. Next, the welding rod 1 is fixed with the 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]
Further, since the insulation resistance C and the insulation resistance F greatly change depending on the individual addition amounts due to the physical properties of the used raw materials, it is necessary to limit the addition amount of the used raw materials, 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 coating cylinder, iron powder is basically contained in the coating agent. However, if the iron powder is contained in an amount exceeding 55% by mass (hereinafter referred to as%), the insulation resistance C becomes low and the insulation resistance becomes low. Although the arc property is improved, the insulation resistance F is also reduced, so that the side arc resistance is deteriorated. Further, the spraying of the arc becomes weak, and the penetration depth becomes shallow. If the addition amount of iron powder is less than 22%, the insulation resistance C increases, and the re-arc property when using a welding machine with an electric shock prevention device is deteriorated. Therefore, the amount of iron powder added needs to be 22 to 55%.
[0017]
Next, as a means for improving the re-arcing property and the side arc resistance, the addition of organic substances such as birch powder and cellulose is effective. Since these are insulating substances, the insulation resistance F increases and the side arc resistance is improved. Let it. In addition, the arc heat generated during welding causes combustion in and around the coating cylinder to generate carbides, thereby lowering insulation resistance C and improving re-arcability. However, when the amount of the organic substance exceeds 3.5%, the amount of diffusible hydrogen increases, and the low hydrogen-based welding rod cannot be realized, and the arc spraying becomes too strong, and the amount of spatter generated increases. If it is less than 0.5%, both the re-arc property and the side arc resistance cannot be improved.
[0018]
By using birch powder as the organic substance, the fiber is thick and long, so that the amount of carbide generated is adjusted to increase the insulation resistance F, thereby further improving the arc resistance. And it can be used alone or in combination with other organic substances in the range of 3.5% or less.
[0019]
Further, the insulation resistance C increases as the amount of non-metallic substances such as metal carbonates and metal fluorides increases, but it is an essential material for satisfying various welding workability.
[0020]
The metal carbonate is decomposed in the arc to generate CO ₂ gas to protect the deposited metal and the molten slag from the atmosphere, to prevent the intrusion of nitrogen, oxygen, and hydrogen and to secure the arcing power, to improve the fluidity of the slag, It adjusts viscosity and requires 20-50%. When the amount of the metal carbonate is less than 20%, the amount of generated gas is small, and the amount of diffusible hydrogen increases easily, and the amount of diffusible hydrogen increases when the amount exceeds 50%. As the metal carbonate, for example, lime carbonate, barium carbonate, magnesium carbonate, sodium carbonate and 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 the slag and obtain a slag having good flowability. If it is less than 0.5%, satisfactory fluidity of the slag cannot be obtained, and the bead shape is deteriorated due to poor slag encapsulation. If it exceeds 3.5%, the fluidity becomes excessively good, and The bead shape deteriorates due to poor properties. As the metal fluoride, for example, fluorite, eternal crystal and sodium fluoride can be used.
[0022]
Further, the coverage of the coating agent also becomes important for the insulation resistances C and F. If the coverage is less than 30%, the insulation resistance F decreases and the side arc resistance deteriorates, and the metal content including the steel core wire increases, so that the slag agent and arc stabilizer are insufficient, and the bead shape is insufficient. Deteriorates. If the covering ratio exceeds 45%, the distance between the tip end of the covering tube and the core portion becomes long and the insulation resistance C increases, so that the re-arc property deteriorates.
[0023]
In addition, the tacking rod of the present invention contains a deoxidizing agent such as ferrosilicon, metallic manganese and ferro-titanium in an amount of not more than 20%, rutile and wollastonite in consideration of mechanical properties and welding workability in addition to the coating agent. 5% or less, a slag forming agent such as silica sand, feldspar and magnesium oxide in a range of 3% or less, and potassium silicate and sodium silicate in a fixing agent in a range of 8% or less.
[0024]
【Example】
Next, the effects of the present invention will be described in more detail with reference to examples.
[0025]
Coatings of various compositions shown in Table 1 were coated on a JIS G3523 SWY11 steel core wire having a diameter of 4.0 mm and a length of 400 mm, and then dried at a maximum temperature of 400 ° C. to produce 20 types of welding rods and various tests. Was carried out.
[0026]
[Table 1]

[0027]
The insulation resistance C was measured by the method shown in FIG. 1 described above repeatedly four times for each trial welding rod, that is, 20 in total.
[0028]
In addition, the insulation resistance F was measured by the method shown in FIG. 2 described above, four times for each trial welding rod, that is, 20 times in total. Table 1 shows the measurement results.
[0029]
Each of the welding rods whose 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 as follows: a steel plate (plate thickness 9 mm, 490 N / mm class ² ) was lightly brought into contact with the fillet of a T-shaped test specimen, and the one that generated an arc immediately at a welding current of 200 A was considered a pass. 80% or more of 16 or more were evaluated as ○, 12 to 15 as Δ, and 11 or less as ×.
[0030]
In addition, each of the welding rods whose insulation resistance F was measured was examined for side arc resistance using a welding machine without an electric shock prevention device. The coating part was lightly contacted with the corner of the same test plate as the test plate whose re-arc property was investigated. What occurred was evaluated as x. Table 2 summarizes the test results.
[0031]
Next, the investigation of welding workability was conducted by assembling the above-mentioned steel sheet into a T-shape, welding with a horizontal fillet and a vertical descent at a welding current of 200 A, arc state, slag state, bead shape, bar burning resistance, etc. investigated. The judgment was a comprehensive judgment of each welding posture, and a good one was marked with 印, and a poor one was marked with x. Table 2 also shows the results of these surveys.
[0032]
[Table 2]

[0033]
In Table 2, welding rod No. 1 to 10 are examples of the present invention; 11 to 20 are comparative examples. The welding rod No. In Nos. 1 to 10, the amounts of metal carbonate, metal fluoride, iron powder and organic matter are appropriate, and the coverage of 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 of the welding machine with the prevention device and the side arc resistance of the welding machine without the electric shock prevention device were good, and the welding workability was also good, which was a very satisfactory result.
[0034]
The welding rod No. in the comparative example. In No. 11, since the amount of metal carbonate in the coating agent was large, the arc was strong and spatter occurred frequently. In addition, since the coating rate was high, the insulation resistance C was high and the re-arc property was deteriorated. Further, since the insulation resistance F was high, the sticking resistance was deteriorated.
[0035]
Welding rod No. In No. 12, the amount of gas generated was insufficient because the amount of metal carbonate in the coating agent was small, and the amount of diffusible hydrogen separately measured was measured. As a result, the amount of diffusible hydrogen was large. Further, since the coverage was low, the insulation resistance F was low, and the side arc resistance was deteriorated. Further, the metal content including the steel core wire was large and the amount of slag generated was small, so that the bead shape was deteriorated.
[0036]
Welding rod No. In No. 13, since the amount of metal fluoride in the coating agent was large, the fluidity of the slag was excessively improved, the slag encapsulating property was deteriorated, and the bead shape was deteriorated. In addition, the amount of organic matter in the coating agent was large, so that the spraying of the arc became too strong, and the amount of spatter generated increased. Also, as a result of measuring the amount of diffusible hydrogen separately performed, the amount of diffusible hydrogen was large.
[0037]
Welding rod No. In No. 14, the organic matter did not contain birch powder, so the slag encapsulation was poor, and the bead shape was deteriorated. In addition, since the amount of organic substances in the coating agent was small, the insulation resistance C was increased and the re-arc property was slightly inferior.
[0038]
Welding rod No. In No. 15, the insulation resistance F was low due to the large amount of iron powder in the coating agent, the side arc property was deteriorated, the arc spraying was weak, and the penetration depth was shallow. Also, 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 agent was small, the insulation resistance C was increased and the re-arc property was deteriorated. Also, the bead shape was deteriorated because the amount of metal fluoride in the coating agent was small.
[0040]
Welding rod No. In No. 17, since the amount of metal carbonate in the coating agent was large, the arc was strong and the amount of spatter generated was large.
[0041]
Welding rod No. Sample No. 18 had a high insulation resistance C due to a small amount of organic matter in the coating agent, and the re-arc 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 the amount of iron powder in the coating agent was large, the insulation resistance F was low, the side arc property was deteriorated, the arc spraying was weak, and the penetration depth was shallow.
[0043]
Welding rod No. In No. 20, since the amount of iron powder in the coating agent was small, the insulation resistance C was increased and the re-arc property was deteriorated.
[0044]
【The invention's effect】
As described above in detail, the low hydrogen-based tacking welding rod of the present invention satisfies welding workability, has excellent re-arc properties even in a welding machine equipped with an electric shock prevention device, and has no load voltage. Since good side arc resistance can be obtained even in a high welding machine, it can greatly contribute to improvement in 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 coating 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 Coating 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

A coating agent containing 20 to 50% 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 by mass% A coating rate of 30 to 45% is applied to the core wire, 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 to 0.20 MΩ. A low-hydrogen-based tacking welding rod, characterized in that:

The low hydrogen based tacking welding rod according to claim 1, wherein the organic substance includes birch powder.