JP2018176283A - Low-hydrogen coated electrode - Google Patents
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本発明は、低水素系被覆アーク溶接棒に関する。 The present invention relates to a low hydrogen-based coated arc welding rod.
従来から、主として火力発電ボイラ内の配管に適用される高Ｃｒフェライト系耐熱鋼の溶接に、低水素系被覆アーク溶接棒が使用されている。 BACKGROUND ART Conventionally, low hydrogen-based coated arc welding rods have been used for welding high-Cr ferritic heat-resistant steels that are applied mainly to piping in thermal power generation boilers.
例えば、特許文献１には、金属炭酸塩：３０〜６０重量％、金属弗化物：１０〜３０重量％、その他に上記以外のアーク安定剤、スラグ生成剤、粘結剤を含む被覆剤を溶接棒全重量に対して２２〜４０重量％となるように鋼心線外周に被覆してなる被覆アーク溶接棒が開示されている。この被覆アーク溶接棒は、前記被覆剤中にＭｇ２Ｓｉ：０．１〜１０重量％を含有せしめ、且つこれら被覆剤と前記鋼心線中の両方又は一方には溶接棒全重量に対してＣ：０．０１〜０．１０重量％、Ｓｉ：０．４〜２．２重量％、Ｍｎ：１．０〜１．９重量％、Ｃｒ：５．９〜９．８重量％、Ｍｏ：０．３〜１．２重量％、Ｎ：０．０４〜０．０９重量％に加えて、Ｎｉ：０．２〜１．０重量％、Ｖ：０．１〜０．４重量％、Ｎｂ：０．０２〜０．１重量％及びＷ：１．１〜２．１重量％よりなる群から選択される１種又は２種以上の元素を含有せしめた９Ｃｒ系鋼溶接用低水素系被覆アーク溶接棒である。 For example, Patent Document 1 welds a coating agent containing 30 to 60% by weight of metal carbonate, 10 to 30% by weight of metal fluoride, and other arc stabilizers, slag forming agents, and binders other than the above. A coated arc welding rod is disclosed which is coated on the outer circumference of a steel core wire so as to be 22 to 40% by weight with respect to the total weight of the rod. This coated arc welding rod contains 0.1 to 10% by weight of Mg 2 Si in the coating, and the coating and / or in the steel core wire relative to the total weight of the welding rod C: 0.01 to 0.10 wt%, Si: 0.4 to 2.2 wt%, Mn: 1.0 to 1.9 wt%, Cr: 5.9 to 9.8 wt%, Mo: 0.3 to 1.2 wt%, N: in addition to 0.04 to 0.09 wt%, Ni: 0.2 to 1.0 wt%, V: 0.1 to 0.4 wt%, Nb Low hydrogen-based coating for welding 9Cr steel containing one or more elements selected from the group consisting of: 0.02 to 0.1 wt% and W: 1.1 to 2.1 wt% It is an arc welding rod.
特許文献１に記載の９Ｃｒ系鋼溶接用低水素系被覆アーク溶接棒は、被覆アーク溶接棒全重量に対する被覆剤の重量％（被覆率）の範囲を、２２〜４０重量％とし、被覆剤中に金属炭酸塩として炭酸Ｃａ、炭酸Ｂａ、炭酸Ｍｇ等を３０〜６０重量％添加することにより、良好な溶接作業性を確保している。 The low hydrogen-based coated arc welding rod for 9Cr-based steel welding described in Patent Document 1 has a range of 22% to 40% by weight of the coating material based on the total weight of the coated arc welding rod, covering percentage being 22% to 40%. By adding 30 to 60% by weight of Ca carbonate, Ba carbonate, Mg carbonate or the like as a metal carbonate, good welding workability is ensured.
しかしながら、従来の技術においては以下の問題がある。
特許文献１に記載の被覆アーク溶接棒では、心線中にＣｒを含有する場合、溶接時の心線のジュール発熱に伴い被覆が分解し、いわゆる「棒焼け」とよばれる現象が発生する。これにより、健全な保護筒が形成されず、アーク安定性が劣化し、スパッタが増加する等、溶接作業性が著しく劣化する。そのため、所望の溶接金属が得られない。
However, the prior art has the following problems.
In the coated arc welding rod described in Patent Document 1, when Cr is contained in the core, the coating is decomposed with Joule heat of the core at the time of welding, and a phenomenon called so-called "stick burn" occurs. As a result, a sound protective cylinder is not formed, the arc stability is degraded, the spatter is increased, and the welding workability is significantly degraded. Therefore, the desired weld metal can not be obtained.
また、従来の技術においては、本願のように、高Ｃｒフェライト系耐熱鋼用低水素系被覆アーク溶接棒として、棒焼けに対する耐性が飛躍的に改善する、即ち、被覆剤の設計を最適化することで耐棒焼け性を改善したというような知見は一切示唆されていない。
また、被覆アーク溶接棒においては、表面の凹凸が少なく外観が良好である優れた塗装性や、溶接金属の欠陥が生じないことも要求されている。
Also, in the prior art, as in the present invention, as a low hydrogen-based coated arc welding rod for high Cr ferritic heat-resistant steel, the resistance to burning of the rod is dramatically improved, that is, the design of the coating is optimized. There is no suggestion of any finding that this has improved the burn resistance.
Moreover, in a coated arc welding rod, it is also requested | required that the coating property which has few surface unevenness | corrugations, and a favorable external appearance and the defect of a weld metal do not arise.
本発明は、上記事情に鑑みてなされたものであり、その課題は、耐棒焼け性、塗装性に優れると共に、耐欠陥性に優れた溶接金属を得ることができる低水素系被覆アーク溶接棒を提供することにある。 The present invention is made in view of the above-mentioned circumstances, and the subject is low hydrogen system covering arc welding rod which can obtain welding metal excellent in resistance to burning and coating and also excellent in defect resistance. To provide.
本発明者等は前記の課題を解決すべく、即ち、従来よりも棒焼けの起こりにくい高Ｃｒフェライト系耐熱鋼用低水素系被覆アーク溶接棒を開発すべく、種々の溶接棒について、実験研究を行った。具体的には、被覆アーク溶接棒についての規定と棒焼けの有無との関係を究明するために実験研究を行った。その結果、以下の事実が判明した。 The present inventors conducted experimental research on various welding rods in order to solve the above-mentioned problems, that is, in order to develop a low hydrogen-based coated arc welding rod for high Cr ferritic heat-resistant steel in which rod burning is less likely to occur. Did. Specifically, an experimental study was conducted to find out the relationship between the rule for the coated arc welding rod and the presence or absence of bar burn. As a result, the following facts were found.
１．耐棒焼け性は、溶接棒の直径を被覆径とし、心線の直径を心線径としたときの比である被覆径／心線径を適正化することによって向上する。
２．耐棒焼け性は、被覆剤の密度を適正化することによって向上する。
３．耐棒焼け性は、フラックス中の炭酸塩の種類を適正化することによって向上する。
1. The burn resistance is improved by optimizing the coating diameter / core diameter, which is the ratio of the diameter of the welding rod to the coating diameter and the core diameter being the core diameter.
2. The burn resistance is improved by optimizing the density of the coating.
3. The burn resistance is improved by optimizing the type of carbonate in the flux.
１については、被覆径／心線径の値を増減させ棒焼けの有無を調査した。
２については、被覆剤の密度を変化させ、棒焼けの有無を調査した。
３については、フラックスの主要な構成成分である炭酸塩の種類を変化させ、棒焼けの有無を調査した。
本発明は、この調査結果に基づき成されたものである。
As for No. 1, the value of the coating diameter / core diameter was increased or decreased to investigate the presence or absence of stick burning.
As for No. 2, the density of the coating was changed, and the presence or absence of stick burning was investigated.
As for No. 3, the type of carbonate, which is a main component of the flux, was changed, and the presence or absence of stick burning was investigated.
The present invention has been made based on the results of this investigation.
すなわち、本発明に係る低水素系被覆アーク溶接棒（以下、適宜、被覆アーク溶接棒あるいは、単に溶接棒という）は、低水素系被覆アーク溶接棒全体中に、前記低水素系被覆アーク溶接棒全質量当たり、合金成分は、Ｃ：０．０１〜０．１５質量％、Ｓｉ：０．５〜１．５質量％、Ｍｎ：０．４〜２．０質量％、Ｃｒ：３．０〜９．０質量％、Ｍｏ：０．０１〜１．５０質量％、Ｆｅ：５５〜７０質量％、を含有し、残部が不可避的不純物であり、前記低水素系被覆アーク溶接棒の被覆剤中に、前記低水素系被覆アーク溶接棒全質量当たり、フラックス成分として、炭酸Ｃａ：ＣＯ２換算値で１〜６質量％、金属弗化物：Ｆ換算値で１〜４質量％、ＳｉＯ２：５〜１５質量％、を含有し、前記被覆剤中に炭酸Ｃａ以外の炭酸塩がＣＯ２換算値で０．１質量％以下含有されており、前記低水素系被覆アーク溶接棒の直径を被覆径とし、心線の直径を心線径としたときの比である被覆径／心線径が１．５０〜１．８０、及び、前記被覆剤の密度が０．２００〜０．２６０（ｇ／ｃｍ３）のいずれか一方又は両方を満足することを特徴とする。 That is, the low hydrogen-based coated arc welding rod according to the present invention (hereinafter appropriately referred to as a coated arc welding rod or simply referred to as a welding rod) comprises the low hydrogen-based coated arc welding rod in the entire low hydrogen-based coated arc welding rod With respect to the total mass, the alloy components are C: 0.01 to 0.15 mass%, Si: 0.5 to 1.5 mass%, Mn: 0.4 to 2.0 mass%, Cr: 3.0 to It contains 9.0% by mass, Mo: 0.01 to 1.50% by mass, Fe: 55 to 70% by mass, the balance being an unavoidable impurity, in the coating material of the low hydrogen-based coated arc welding rod The total content of the low hydrogen-based coated arc welding rod as a flux component is 1 to 6 mass% of Ca carbonate: CO 2 conversion value, 1 to 4 mass% of metal fluoride: F conversion value, SiO 2 : 5 15 wt%, contains a carbonate salt other than Ca carbonate in the coating agent is CO 2 conversion The coating diameter / core diameter which is the ratio when the diameter of the low hydrogen system coated arc welding rod is made the coating diameter and the diameter of the core wire is the core diameter which is 0.1 mass% or less by calculation And the density of the coating agent satisfies either one or both of 0.200 to 0.260 (g / cm 3 ).
かかる構成によれば、低水素系被覆アーク溶接棒は、Ｃ、Ｓｉ、Ｍｎ、Ｃｒ、Ｍｏ、Ｆｅを所定量含有することで、溶接金属の強度、クリープ強度、靭性、耐食性、耐欠陥性が向上し、また被覆剤の絶縁性が向上する。
また、低水素系被覆アーク溶接棒は、炭酸ＣａのＣＯ２換算値、金属弗化物のＦ換算値、ＳｉＯ２についての含有量を規定することで、溶接作業性、凝固スラグの剥離性が向上し、また、溶接金属のビード外観が良好となる。また、スパッタの発生が抑制される。
また、低水素系被覆アーク溶接棒は、被覆剤中に炭酸Ｃａ以外の炭酸塩がＣＯ２換算値で０．１質量％以下の含有であることで、耐棒焼け性が向上する。
また、低水素系被覆アーク溶接棒は、被覆径／心線径の規定、及び、被覆剤の密度の規定のいずれか一方又は両方を満たすことで、耐棒焼け性、塗装性が向上し、また、溶接金属の耐欠陥性が向上するとともに、ビード外観が良好となる。また、スパッタの発生が抑制される。
According to this configuration, the low hydrogen-based coated arc welding rod contains C, Si, Mn, Cr, Mo, and Fe in a predetermined amount, whereby the strength, creep strength, toughness, corrosion resistance, and defect resistance of the weld metal are improved. It also improves the insulation of the coating.
In addition, low hydrogen-based coated arc welding rods have improved welding workability and peelability of solidified slag by specifying the content of Ca carbonate in terms of CO 2 conversion value, metal fluoride content in terms of F conversion value, and SiO 2 content. Also, the bead appearance of the weld metal is good. In addition, generation of spatter is suppressed.
In addition, in the low hydrogen-based coated arc welding rod, when the carbonate other than Ca carbonate is contained in the coating agent at 0.1% by mass or less in terms of CO 2 conversion, the burnt resistance is improved.
In addition, in the low hydrogen-based coated arc welding rod, the rod burn resistance and the paintability are improved by satisfying one or both of the coating diameter / core diameter specification and the coating density specification. Moreover, while the defect resistance of a weld metal improves, bead appearance becomes favorable. In addition, generation of spatter is suppressed.
また、本発明に係る低水素系被覆アーク溶接棒は、前記Ｃｒの含有量が、前記低水素系被覆アーク溶接棒全質量当たり、５．０〜９．０質量％であり、前記低水素系被覆アーク溶接棒全体中に、前記低水素系被覆アーク溶接棒全質量当たり、合金成分として、さらに、Ｎｉ：１．０質量％以下、Ｔｉ：０．５質量％以下、Ｖ：０．５質量％以下、Ｎｂ：０．５質量％以下を含有することが好ましい。 In the low hydrogen-based coated arc welding rod according to the present invention, the content of the Cr is 5.0 to 9.0% by mass based on the total mass of the low hydrogen-based coated arc welding rod, Further, Ni: not more than 1.0% by mass, Ti: not more than 0.5% by mass, V: not more than 0.5% by mass as the alloy component per total mass of the low hydrogen-based coated arc welding rod in the entire coated arc welding rod It is preferable to contain% or less and Nb: 0.5 mass% or less.
かかる構成によれば、低水素系被覆アーク溶接棒は、Ｃｒの含有量を５．０〜９．０質量％とすることで、耐食性がさらに向上する。また、低水素系被覆アーク溶接棒は、Ｎｉ、Ｔｉ、Ｖ、Ｎｂを所定量含有することで、溶接金属のクリープ強度、靭性が向上する。 According to this configuration, the corrosion resistance of the low hydrogen-based coated arc welding rod is further improved by setting the content of Cr to 5.0 to 9.0 mass%. Further, the creep strength and toughness of the weld metal are improved by containing a predetermined amount of Ni, Ti, V, and Nb in the low hydrogen-based coated arc welding rod.
また、前記低水素系被覆アーク溶接棒全体中に、前記低水素系被覆アーク溶接棒全質量当たり、合金成分として、さらに、Ｎ：０．１０質量％以下を含有することが好ましい。 Preferably, the entire low hydrogen-based coated arc welding rod further contains N: 0.10% by mass or less as the alloy component per total mass of the low hydrogen-based coated arc welding rod.
かかる構成によれば、低水素系被覆アーク溶接棒は、Ｎを所定量含有することで、溶接金属のクリープ強度、靭性、耐ブローホール性が向上する。 According to this configuration, by containing a predetermined amount of N, the low hydrogen-based coated arc welding rod improves the creep strength, toughness and blowhole resistance of the weld metal.
また、前記低水素系被覆アーク溶接棒全体中に、前記低水素系被覆アーク溶接棒全質量当たり、合金成分として、さらに、Ｃｏ：２．０質量％以下、Ｗ：２．０質量％以下を含有することが好ましい。 Further, Co: 2.0 mass% or less, W: 2.0 mass% or less as an alloy component per total mass of the low hydrogen-based coated arc welding rod in the entire low hydrogen-based coated arc welding rod It is preferable to contain.
かかる構成によれば、低水素系被覆アーク溶接棒は、Ｃｏ、Ｗを所定量含有することで、溶接金属のクリープ強度、靭性が向上する。 According to this configuration, the creep strength and toughness of the weld metal are improved by containing a predetermined amount of Co and W in the low hydrogen-based coated arc welding rod.
本発明に係る低水素系被覆アーク溶接棒は、耐棒焼け性に優れるため、優れた溶接作業性を確保することができる。また、本発明に係る低水素系被覆アーク溶接棒は、塗装性に優れたものであり、また、耐欠陥性に優れた溶接金属を得ることができる。 The low hydrogen-based coated arc welding rod according to the present invention is excellent in burn-out resistance, so that excellent welding workability can be secured. Moreover, the low hydrogen-based coated arc welding rod according to the present invention is excellent in paintability, and can obtain a weld metal excellent in defect resistance.
以下、本発明の実施の形態について詳細に説明する。
本発明の被覆アーク溶接棒は、心線及び被覆剤の一方又は双方の中に、被覆アーク溶接棒全質量当たり、合金成分として、Ｃ、Ｓｉ、Ｍｎ、Ｃｒ、Ｍｏ、Ｆｅを所定量含有する。また、被覆アーク溶接棒は、被覆剤中に、被覆アーク溶接棒全質量当たり、フラックス成分として、炭酸Ｃａ、金属弗化物、ＳｉＯ２を所定量含有する。なお、炭酸ＣａはＣＯ２換算値、金属弗化物はＦ換算値としたものである。
また、被覆アーク溶接棒は、被覆剤中に炭酸Ｃａ以外の炭酸塩を実質的に含有していない。
さらに、被覆アーク溶接棒は、被覆アーク溶接棒の直径を被覆径とし、心線の直径を心線径としたときの比である被覆径／心線径が１．５０〜１．８０、及び、被覆剤の密度が０．２００〜０．２６０（ｇ/ｃｍ３）のいずれか一方もしくは両方を満足する。
Hereinafter, embodiments of the present invention will be described in detail.
The coated arc welding rod of the present invention contains predetermined amounts of C, Si, Mn, Cr, Mo, and Fe as alloy components per total mass of the coated arc welding rod in one or both of the core wire and the coating. . In addition, the coated arc welding rod contains a predetermined amount of Ca carbonate, metal fluoride and SiO 2 as a flux component per total mass of the coated arc welding rod in the coating material. Incidentally, Ca carbonate is a CO 2 converted value, and metal fluoride is a F converted value.
In addition, the coated arc welding rod contains substantially no carbonate other than Ca carbonate in the coating.
Further, the coated arc welding rod has a coating diameter / core diameter of 1.50 to 1.80, which is a ratio when the diameter of the coated arc welding rod is the coating diameter and the core diameter is the core diameter. And the density of the coating agent satisfies either one or both of 0.200 to 0.260 (g / cm 3 ).
以下、各合金元素の添加理由及び組成限定理由について詳細に説明する。これらの元素は、心線及び被覆剤のいずれに添加してもよく、両方に添加してもよい。 Hereinafter, the reason for addition of each alloy element and the reason for limitation of the composition will be described in detail. These elements may be added to any of the cord and the coating agent, and may be added to both.
［Ｃ：０．０１〜０．１５質量％］
Ｃはオーステナイトを安定化させる元素のひとつであり、溶接金属の強度を向上させる効果を有する。また、Ｃは低靱性となるδフェライトの抑制作用を有する。Ｃ含有量が０．０１質量％未満では、これらの効果が発揮されない。一方、０．１５質量％を超えると、凝固割れ感受性が高まり、また炭化物析出量が増大して溶接金属の強度を高め、靭性を劣化させる。したがって、Ｃ含有量は、被覆アーク溶接棒全質量あたり０．０１〜０．１５質量％とする。Ｃ含有量は、過剰添加による前記の不具合をより抑制する観点から、好ましくは０．１２質量％以下である。なお、Ｃは被覆剤から添加する場合は、他の金属原料に含有させて添加することができる。
[C: 0.01 to 0.15 mass%]
C is one of the elements that stabilize austenite, and has the effect of improving the strength of the weld metal. Further, C has a suppressing effect of δ ferrite which has low toughness. When the C content is less than 0.01% by mass, these effects are not exhibited. On the other hand, if it exceeds 0.15% by mass, solidification cracking sensitivity is increased and the amount of precipitated carbides is increased to increase the strength of the weld metal and to deteriorate the toughness. Therefore, the C content is 0.01 to 0.15 mass% per total mass of the coated arc welding rod. The C content is preferably 0.12% by mass or less from the viewpoint of suppressing the above-mentioned problems due to excessive addition. When C is added from the coating agent, it can be added to other metal raw materials.
［Ｓｉ：０．５〜１．５質量％］
Ｓｉは脱酸剤として機能して溶接金属の強度及び靭性を向上させる。また、Ｓｉはクレータ形成に大きな影響を与え、立向き上進溶接には不可欠の成分である。Ｓｉ含有量が０．５質量％未満では、これらの効果が発揮されない。一方、１．５質量％を超えると、過剰な強度上昇が生じ、靱性を劣化させる。したがって、Ｓｉ含有量は、被覆アーク溶接棒全質量あたり０．５〜１．５質量％とする。Ｓｉ含有量は、過剰添加による前記の不具合をより抑制する観点から、好ましくは１．０質量％以下である。なお、Ｓｉは被覆剤から添加する場合、Ｆｅ−Ｓｉ等により添加することができる。
[Si: 0.5 to 1.5% by mass]
Si functions as a deoxidizer to improve the strength and toughness of the weld metal. In addition, Si has a great influence on crater formation, and is an essential component for uplift welding. When the Si content is less than 0.5% by mass, these effects can not be exhibited. On the other hand, if it exceeds 1.5% by mass, an excessive increase in strength occurs to deteriorate the toughness. Therefore, the Si content is 0.5 to 1.5% by mass based on the total mass of the coated arc welding rod. The Si content is preferably 1.0% by mass or less from the viewpoint of suppressing the above-mentioned problems due to excessive addition. In addition, when adding from a coating agent, Si can be added by Fe-Si etc.
［Ｍｎ：０．４〜２．０質量％］
ＭｎはＡ１変態点及びベイナイト変態開始温度を低下させてベイナイト組織を微細化し、Ｓｉ同様に脱酸剤として機能して溶接金属の強度及び靭性を向上させる。Ｍｎ含有量が０．４質量％未満では、これらの効果が発揮されない。一方、２．０質量％を超えると、クリープ強度の劣化を引き起こす。したがって、Ｍｎ含有量は、被覆アーク溶接棒全質量あたり０．４〜２．０質量％とする。Ｍｎ含有量は、過剰添加による前記の不具合をより抑制する観点から、好ましくは１．５質量％以下である。なお、Ｍｎは被覆剤から添加する場合、Ｆｅ−Ｍｎ、金属Ｍｎ等により添加することができる。
[Mn: 0.4 to 2.0 mass%]
Mn lowers the A1 transformation point and the bainite transformation start temperature to refine the bainite structure, and like Si, functions as a deoxidizer to improve the strength and toughness of the weld metal. If the Mn content is less than 0.4% by mass, these effects can not be exhibited. On the other hand, when it exceeds 2.0 mass%, deterioration of creep strength is caused. Therefore, the Mn content is 0.4 to 2.0% by mass based on the total mass of the coated arc welding rod. The Mn content is preferably 1.5% by mass or less from the viewpoint of further suppressing the above-mentioned problems due to excessive addition. In addition, when adding from a coating agent, Mn can be added by Fe-Mn, metal Mn, etc.
［Ｃｒ：３．０〜９．０質量％］
Ｃｒは溶接金属の耐食性を向上させると共に、固溶強化によるクリープ強度を維持する効果を有する。Ｃｒ含有量が３．０質量％未満では、これらの効果が発揮されない。一方、９．０質量％を超えると、δフェライトの析出により靭性を劣化させる。したがって、Ｃｒ含有量は、被覆アーク溶接棒全質量あたり３．０〜９．０質量％とする。特に、より高い耐食性が要求される場合は、Ｃｒ含有量は、５．０〜９．０質量％とすることが好ましい。なお、Ｃｒは被覆剤から添加する場合、Ｆｅ−Ｃｒ、金属Ｃｒ等として添加することができる。
[Cr: 3.0 to 9.0 mass%]
Cr improves the corrosion resistance of the weld metal and has the effect of maintaining the creep strength by solid solution strengthening. If the Cr content is less than 3.0% by mass, these effects can not be exhibited. On the other hand, if it exceeds 9.0% by mass, the precipitation of δ ferrite degrades the toughness. Therefore, the Cr content is set to 3.0 to 9.0 mass% per total mass of the coated arc welding rod. In particular, when higher corrosion resistance is required, the Cr content is preferably 5.0 to 9.0% by mass. In addition, when adding from a coating agent, Cr can be added as Fe-Cr, metal Cr, etc.
［Ｍｏ：０．０１〜１．５０質量％］
ＭｏはＰＷＨＴ（Post Weld Heat Treatment：溶接後熱処理）過程でＣｒ系炭化物中あるいは母相中に固溶して溶接金属のクリープ強度を維持する効果を有する。Ｍｏ含有量が０．０１質量％未満では、その効果が発揮されない。一方、１．５０質量を超えると、過剰な強度の上昇により靭性を劣化させる。したがって、Ｍｏ含有量は、被覆アーク溶接棒全質量あたり０．０１〜１．５０質量％とする。Ｍｏ含有量は、過剰添加による前記の不具合をより抑制する観点から、好ましくは１．０質量％以下である。なお、Ｍｏは被覆剤から添加する場合、Ｆｅ−Ｍｏ合金等として添加することができる。
[Mo: 0.01 to 1.50% by mass]
Mo has the effect of maintaining the creep strength of the weld metal by solid solution in the Cr-based carbide or in the matrix during the PWHT (Post Weld Heat Treatment) process. If the Mo content is less than 0.01% by mass, the effect is not exhibited. On the other hand, if it exceeds 1.50 mass, the toughness is deteriorated due to the increase of the excessive strength. Therefore, the Mo content is 0.01 to 1.50 mass% per total mass of the coated arc welding rod. The Mo content is preferably 1.0% by mass or less from the viewpoint of suppressing the above-mentioned problems due to excessive addition. In addition, when adding from a coating agent, Mo can be added as a Fe-Mo alloy etc.
［Ｆｅ：５５〜７０質量％］
Ｆｅは心線及び、被覆剤中の鉄粉又はＦｅ合金として添加することができる。Ｆｅ含有量が５５質量％未満では、スラグ量が過大になりスラグ巻込み等の欠陥が発生しやすくなる。一方、７０質量％を超えると、被覆剤の絶縁性が劣化する。したがって、Ｆｅ含有量は、被覆アーク溶接棒全質量あたり５５〜７０質量％とする。
[Fe: 55 to 70% by mass]
Fe can be added as a core wire and iron powder or Fe alloy in a coating. If the Fe content is less than 55% by mass, the amount of slag becomes excessive and defects such as slag inclusion are likely to occur. On the other hand, when it exceeds 70 mass%, the insulation of a coating material will deteriorate. Accordingly, the Fe content is 55 to 70% by mass based on the total mass of the coated arc welding rod.
被覆アーク溶接棒は、心線及び被覆剤の一方又は双方の中に、被覆アーク溶接棒全質量当たり、合金成分として、さらに、Ｎｉ、Ｔｉ、Ｖ、Ｎｂを所定量含有することが好ましい。また、Ｎｉ、Ｔｉ、Ｖ、Ｎｂを所定量含有する場合、Ｃｒ含有量を、被覆アーク溶接棒全質量当たり、５．０〜９．０質量％とすることが好ましい。なお、Ｎｉ、Ｔｉ、Ｖ、Ｎｂは、これらの成分のうち、いずれか一種以上を含有するものであってもよい。 The coated arc welding rod preferably contains a predetermined amount of Ni, Ti, V, Nb as an alloy component per total mass of the coated arc welding rod in one or both of the core wire and the coating. When Ni, Ti, V and Nb are contained in a predetermined amount, the Cr content is preferably 5.0 to 9.0% by mass based on the total mass of the coated arc welding rod. Note that Ni, Ti, V, and Nb may contain any one or more of these components.
［Ｎｉ：１．０質量％以下］
Ｎｉは必須元素ではないが、オーステナイトを安定化させる元素として機能し、低靱性となるδフェライト相の残存を抑制する。一方、過剰になるとクリープ強度を劣化させる。よって、Ｎｉは、δフェライト相が析出しやすい成分系の場合は、被覆アーク溶接棒全質量あたり１．０質量％を超えない範囲で添加することが好ましい。Ｎｉ含有量は、過剰添加による前記の不具合をより抑制する観点から、より好ましくは０．６質量％以下である。なお、Ｎｉは被覆剤から添加する場合、金属Ｎｉ、Ｎｉ−Ｍｇ等で添加することができる。
[Ni: not more than 1.0% by mass]
Although Ni is not an essential element, it functions as an element that stabilizes austenite, and suppresses the remaining of the δ ferrite phase which has low toughness. On the other hand, when it becomes excessive, creep strength is degraded. Therefore, in the case of a component system in which the δ ferrite phase tends to precipitate, it is preferable to add Ni in a range not exceeding 1.0% by mass with respect to the total mass of the coated arc welding rod. The Ni content is more preferably 0.6% by mass or less from the viewpoint of suppressing the above-mentioned problems due to excessive addition. In addition, when adding from a coating agent, Ni can be added by metal Ni, Ni-Mg, etc.
［Ｔｉ：０．５質量％以下］
Ｔｉは必須元素ではないが、溶接時の凝固過程及びＰＷＨＴ時に微細な炭窒化物を形成し、クリープ強度を向上させる。一方、過剰になると溶接金属の強度が著しく高まり、靭性を劣化させる。よって、Ｔｉは、より高いクリープ強度が要求される場合は、被覆アーク溶接棒全質量あたり０．５質量％を超えない範囲で添加することが好ましい。Ｔｉ含有量は、過剰添加による前記の不具合をより抑制する観点から、より好ましくは０．３質量％以下である。なお、Ｔｉは被覆剤から添加する場合、Ｆｅ−Ｔｉ等で添加することができる。
[Ti: 0.5 mass% or less]
Although Ti is not an essential element, it forms fine carbonitrides during the solidification process during welding and during PWHT, and improves the creep strength. On the other hand, when it becomes excessive, the strength of the weld metal is significantly increased and the toughness is degraded. Therefore, when higher creep strength is required, it is preferable to add Ti in a range not exceeding 0.5% by mass based on the total mass of the coated arc welding rod. The Ti content is more preferably 0.3% by mass or less from the viewpoint of suppressing the above-mentioned problems due to excessive addition. In addition, when adding from a coating agent, Ti can be added by Fe-Ti etc.
［Ｖ：０．５質量％以下］
Ｖは必須元素ではないが、ＰＷＨＴ過程で炭窒化物を形成し、溶接金属のクリープ強度を向上させる。一方、過剰になると炭窒化物の析出量が著しく増加して溶接金属の強度が高まり、靱性を劣化させる。よって、Ｖは、より高いクリープ強度が要求される場合は、被覆アーク溶接棒全質量あたり０．５質量％を超えない範囲で添加することが好ましい。Ｖ含有量は、過剰添加による前記の不具合をより抑制する観点から、より好ましくは０．３質量％以下である。なお、Ｖは被覆剤から添加する場合、Ｆｅ−Ｖ等で添加することができる。
[V: 0.5 mass% or less]
Although V is not an essential element, it forms carbonitrides in the PWHT process and improves the creep strength of the weld metal. On the other hand, when it becomes excessive, the precipitation amount of carbonitrides significantly increases, the strength of the weld metal increases, and the toughness is deteriorated. Therefore, it is preferable to add V in the range which does not exceed 0.5 mass% per total mass of a coated arc welding rod, when higher creep strength is required. The V content is more preferably 0.3% by mass or less from the viewpoint of suppressing the above-mentioned problems due to excessive addition. In addition, V can be added by Fe-V etc., when adding from a coating agent.
［Ｎｂ：０．５質量％以下］
Ｎｂは必須元素ではないが、Ｖ同様にＰＷＨＴ過程で炭窒化物を形成し、溶接金属のクリープ強度を向上させる。一方、過剰になると炭窒化物の析出量が著しく増加して溶接金属の強度が高まり、靱性を劣化させる。よって、Ｎｂは、より高いクリープ強度が要求される場合は、被覆アーク溶接棒全質量あたり０．５質量％を超えない範囲で添加することが好ましい。Ｎｂ含有量は、過剰添加による前記の不具合をより抑制する観点から、より好ましくは０．３質量％以下、さらに好ましくは０．１質量％以下である。なお、Ｎｂは被覆剤から添加する場合、Ｆｅ−Ｎｂ等で添加することができる。
[Nb: 0.5% by mass or less]
Nb is not an essential element, but like V, it forms carbonitrides in the PWHT process and improves the creep strength of the weld metal. On the other hand, when it becomes excessive, the precipitation amount of carbonitrides significantly increases, the strength of the weld metal increases, and the toughness is deteriorated. Therefore, when higher creep strength is required, Nb is preferably added in a range not exceeding 0.5% by mass based on the total mass of the coated arc welding rod. The Nb content is more preferably 0.3% by mass or less, still more preferably 0.1% by mass or less, from the viewpoint of further suppressing the above-mentioned problems caused by excessive addition. In addition, when adding from a coating agent, Nb can be added by Fe-Nb etc.
被覆アーク溶接棒は、心線及び被覆剤の一方又は双方の中に、被覆アーク溶接棒全質量当たり、合金成分として、さらに、Ｎを所定量含有することが好ましい。 The coated arc welding rod preferably further contains a predetermined amount of N as an alloy component per total mass of the coated arc welding rod in one or both of the core wire and the coating.
［Ｎ：０．１０質量％以下］
Ｎは必須元素ではないが、ＰＷＨＴ過程でＣｒ等と結合して炭窒化物を形成し、溶接金属のクリープ強度を向上させる。一方、過剰になると炭窒化物の析出量が増加して溶接金属の強度が高まり、靱性を劣化させる。さらに、Ｎ含有量が多くなると溶接時の溶融金属中にＮ２ガスが発生し、ブローホールを発生させる。よって、Ｎは、より高いクリープ強度が要求される場合は、被覆アーク溶接棒全質量あたり０．１０質量％を超えない範囲で添加することが好ましい。Ｎ含有量は、過剰添加による前記の不具合をより抑制する観点から、より好ましくは０．０５質量％以下である。なお、Ｎは被覆剤から添加する場合、Ｃｒ−Ｎ等で添加することができる。
[N: 0.10 mass% or less]
Although N is not an essential element, it combines with Cr or the like in the PWHT process to form carbonitrides and improves the creep strength of the weld metal. On the other hand, when it becomes excessive, the precipitation amount of carbonitrides increases, the strength of the weld metal increases, and the toughness is degraded. Furthermore, when the N content increases, N 2 gas is generated in the molten metal at the time of welding to generate blow holes. Therefore, when higher creep strength is required, N is preferably added in a range not exceeding 0.10% by mass with respect to the total mass of the coated arc welding rod. The N content is more preferably 0.05% by mass or less from the viewpoint of suppressing the above-mentioned problems due to excessive addition. In addition, when adding from a coating agent, N can be added by Cr-N etc.
被覆アーク溶接棒は、心線及び被覆剤の一方又は双方の中に、被覆アーク溶接棒全質量当たり、合金成分として、さらに、Ｃｏ、Ｗを所定量含有することが好ましい。なお、Ｃｏ、Ｗは、これらの成分のうち、いずれか一種以上を含有するものであってもよい。 The coated arc welding rod preferably contains a predetermined amount of Co, W as an alloy component per total mass of the coated arc welding rod in one or both of the core wire and the coating. Co and W may contain any one or more of these components.
［Ｃｏ：２．０質量％以下］
Ｃｏは必須元素ではないが、オーステナイトを安定化させる元素として機能し、δフェライト相の残存を抑制する。一方、過剰になると溶接金属の強度が著しく向上し、靱性を劣化させる。よって、Ｃｏは、δフェライト相が析出しやすい成分系の場合は、被覆アーク溶接棒全質量あたり２．０質量％を超えない範囲で添加することが好ましい。Ｃｏ含有量は、過剰添加による前記の不具合をより抑制する観点から、より好ましくは１．０質量％以下である。また、前記の効果をより向上させる観点から、０．１質量％以上添加することが好ましい。なお、Ｃｏは被覆剤から添加する場合、金属Ｃｏ等で添加することができる。
[Co: 2.0 mass% or less]
Co is not an essential element, but functions as an element that stabilizes austenite and suppresses the remaining of the δ ferrite phase. On the other hand, when it becomes excessive, the strength of the weld metal is significantly improved and the toughness is deteriorated. Therefore, in the case of a component system in which the δ ferrite phase tends to precipitate, it is preferable to add Co in a range not exceeding 2.0% by mass with respect to the total mass of the coated arc welding rod. The Co content is more preferably 1.0% by mass or less from the viewpoint of suppressing the above-mentioned problems due to excessive addition. Moreover, it is preferable to add 0.1 mass% or more from a viewpoint of improving the said effect more. In addition, Co can be added by metal Co etc., when adding from a coating agent.
［Ｗ：２．０質量％以下］
Ｗは必須元素ではないが、Ｍｏと同様に、固溶強化によりクリープ強度を維持する効果を有する。一方、過剰になると強度の上昇とδフェライトの析出により靭性を劣化させる。よって、Ｗは、より高いクリープ強度が要求される場合は、被覆アーク溶接棒全質量あたり２．０質量％を超えない範囲で添加することが好ましい。Ｗ含有量は、過剰添加による前記の不具合をより抑制する観点から、より好ましくは１．５質量％以下である。なお、Ｗは被覆剤から添加する場合、Ｆｅ−Ｗ等で添加することができる。
[W: 2.0 mass% or less]
W is not an essential element but, like Mo, it has the effect of maintaining the creep strength by solid solution strengthening. On the other hand, when it becomes excessive, the toughness is deteriorated due to the increase in strength and the precipitation of δ ferrite. Therefore, W is preferably added in a range not exceeding 2.0% by mass based on the total mass of the coated arc welding rod, when higher creep strength is required. The W content is more preferably 1.5% by mass or less from the viewpoint of suppressing the above-mentioned problems due to excessive addition. In addition, W can be added by Fe-W etc., when adding from a coating agent.
［その他の成分］
合金成分のうち、その他の成分として、Ｐ及びＳ等の不可避的不純物が挙げられるが、これらの成分はできるだけ抑制することが好ましい。
[Other ingredients]
Among the alloy components, as other components, unavoidable impurities such as P and S can be mentioned, but it is preferable to suppress these components as much as possible.
次に、被覆剤中（フラックス中）の各元素の添加理由及び組成限定理由について詳細に説明する。
［炭酸ＣａのＣＯ２換算値：１〜６質量％］
炭酸Ｃａの含有量がＣＯ２換算値で１質量％未満では、溶融スラグの粘性が低くなりすぎて溶接中にスラグが先行しやすくなり溶接作業性が劣化する他、凝固スラグ剥離性が劣化する。一方、６質量％を超えると、溶融スラグ粘性が高くなりすぎてスパッタが増加すると共にビード外観も悪くなる。したがって、炭酸Ｃａの含有量は、ＣＯ２換算値で、被覆アーク溶接棒全質量あたり１〜６質量％とする。炭酸Ｃａの含有量は、過剰添加による前記の不具合をより抑制する観点から、ＣＯ２換算値で、好ましくは５質量％以下である。
Next, the reason for adding each element in the coating agent (in the flux) and the reason for limiting the composition will be described in detail.
[CO 2 conversion value of Ca carbonate: 1 to 6% by mass]
If the content of Ca carbonate is less than 1% by mass in terms of CO 2 conversion, the viscosity of the molten slag becomes too low to easily lead slag during welding, and welding workability deteriorates, and solidified slag removability also deteriorates. . On the other hand, if it exceeds 6% by mass, the viscosity of the molten slag becomes too high, spatter increases and the bead appearance also deteriorates. Therefore, the content of Ca carbonate is set to 1 to 6% by mass based on the total mass of the coated arc welding rod in terms of CO 2 . The content of Ca carbonate is preferably 5% by mass or less in terms of CO 2 from the viewpoint of suppressing the above-mentioned problems due to excessive addition.
本発明では、金属炭酸塩は炭酸Ｃａのみを使用し、被覆剤中に炭酸Ｃａ以外の炭酸塩を実質的に含有しないものとする。その理由は、フラックス中の金属炭酸塩として炭酸Ｃａよりも分解温度の低い炭酸Ｂａや炭酸Ｍｇ並びに炭酸Ｓｒを単独又は同時に用いた場合、棒焼けが発生するためである。耐棒焼け性を維持するためには、適用する金属炭酸塩を実質的に炭酸Ｃａのみとする必要がある。なお、実質的に含有しないとは、炭酸Ｃａ以外の金属炭酸塩の含有量を、被覆アーク溶接棒全質量あたり０．１質量％以下に抑えることをいう。すなわち、実質的に含有しないとは、炭酸Ｃａ以外の炭酸塩が、不可避的不純物としてＣＯ２換算で０．１質量％以下含有されていることを意味する。炭酸Ｃａ以外の炭酸塩は、ＣＯ２換算で０．１質量％までの含有であれば耐棒焼け性を劣化させることがない。 In the present invention, it is assumed that only carbonate Ca is used as the metal carbonate, and the coating agent contains substantially no carbonate other than Ca carbonate. The reason is that, when using Ba carbonate or Mg carbonate having a decomposition temperature lower than that of Ca carbonate as a metal carbonate in the flux or Mg carbonate and Sr carbonate singly or simultaneously, burns occur. In order to maintain the burn resistance, it is necessary to make the applied metal carbonate substantially only Ca carbonate. In addition, containing substantially does not suppress content of metal carbonates other than Ca carbonate to 0.1 mass% or less per total mass of a coated arc welding rod. That is, the substantially free, carbonate salts other than carbonate Ca is meant that is contained 0.1 wt% or less in terms of CO 2 as inevitable impurities. If the content of carbonates other than Ca carbonate is up to 0.1% by mass in terms of CO 2 , the burnt resistance does not deteriorate.
［金属弗化物のＦ換算値：１〜４質量％］
金属弗化物の含有量がＦ換算値で１質量％未満では、溶融スラグの粘性が高くなりすぎてビード外観が劣化する。一方、４質量％を超えると、溶融スラグの粘性が低くなりすぎて溶接作業性が劣化する。したがって、金属弗化物の含有量は、Ｆ換算値で、被覆アーク溶接棒全質量あたり１〜４質量％とする。金属弗化物の含有量は、過剰添加による前記の不具合をより抑制する観点から、Ｆ換算値で、好ましくは３質量％以下である。なお、金属弗化物は、ＣａＦ２等で添加することができる。
[F conversion value of metal fluoride: 1 to 4% by mass]
If the content of the metal fluoride is less than 1% by mass in terms of F, the viscosity of the molten slag becomes too high and the bead appearance is degraded. On the other hand, if it exceeds 4% by mass, the viscosity of the molten slag becomes too low to deteriorate the welding workability. Therefore, the content of the metal fluoride is, in terms of F, 1 to 4% by mass based on the total mass of the coated arc welding rod. The content of the metal fluoride is preferably 3% by mass or less in terms of F, from the viewpoint of suppressing the above-mentioned problems due to the excessive addition. The metal fluoride can be added as CaF 2 or the like.
［ＳｉＯ２：５〜１５質量％］
ＳｉＯ２含有量が５質量％未満では、溶接作業性が劣化すると共にビード外観も悪くなる。一方、１５質量％を超えると、溶融スラグの粘性が低くなって凝固スラグの剥離性が劣化する他、スパッタ発生量も増加する。したがって、ＳｉＯ２含有量は、被覆アーク溶接棒全質量あたり５〜１５質量％とする。
[SiO 2 : 5 to 15% by mass]
When the SiO 2 content is less than 5% by mass, welding workability is deteriorated and the bead appearance is also deteriorated. On the other hand, if it exceeds 15% by mass, the viscosity of the molten slag is lowered to deteriorate the removability of the solidified slag, and the spatter generation amount also increases. Therefore, the SiO 2 content is 5 to 15% by mass based on the total mass of the coated arc welding rod.
［その他の成分］
その他の成分として被覆剤中には、炭酸Ｃａ、金属弗化物、ＳｉＯ２以外のアーク安定剤及びスラグ生成剤（ＭｇＯ等）と、Ｎａ２Ｏ、Ｋ２Ｏ、Ｌｉ２Ｏ等のアルカリ金属酸化物が含まれる。
[Other ingredients]
In the coating agent as other components, Ca carbonate, metal fluorides, arc stabilizers other than SiO 2 and slag forming agents (such as MgO) and alkali metal oxides such as Na 2 O, K 2 O, Li 2 O, etc. Objects are included.
以下、被覆径／心線径、及び被覆剤の密度の数値限定理由について詳細に説明する。
これらの規定については、いずれか一方もしくは両方を満足しなければならない。
Hereinafter, the reasons for numerical limitation of the coating diameter / core diameter and the density of the coating will be described in detail.
One or both of these requirements must be satisfied.
［被覆径／心線径：１．５０〜１．８０］
被覆径／心線径の規定は、被覆剤の密度が規定を満たさない場合は、１．５０〜１．８０とする。被覆径／心線径が１．５０未満では、棒焼けにより保護筒としての機能が不十分になり、アーク安定性が劣化し、スパッタが増加するだけでなく、生成スラグ量の不足によってビード外観が劣化する。一方、１．８０を超えると、スラグ量が多くなりすぎるためにスラグ巻込み等の欠陥が発生しやすくなると共に、開先幅の狭い溶接継手に適用した場合に運棒が困難になる。したがって、被覆径／心線径は１．５０〜１．８０とする。被覆径／心線径は、前記の効果をより向上させる観点から、好ましくは１．５５以上、より好ましくは１．６０以上である。
ただし、被覆剤の密度が規定を満たしていれば、被覆径／心線径は前記規定を満たさなくても問題ない。
[Coating diameter / core diameter: 1.50 to 1.80]
The coating diameter / core diameter is set to 1.50 to 1.80 when the density of the coating does not meet the specification. If the coating diameter / core diameter is less than 1.50, rod burning causes the function as a protective cylinder to be insufficient, the arc stability deteriorates, and spatter increases, and the amount of generated slag also causes bead appearance Is degraded. On the other hand, if it exceeds 1.80, the amount of slag is too large, so defects such as slag inclusion are likely to occur, and when it is applied to a welded joint having a narrow groove width, the rod becomes difficult. Therefore, the coating diameter / core diameter is set to 1.50 to 1.80. The coating diameter / core diameter is preferably 1.55 or more, more preferably 1.60 or more, from the viewpoint of further improving the above-mentioned effects.
However, if the density of the coating agent satisfies the specification, there is no problem even if the coating diameter / core diameter does not satisfy the above-mentioned specification.
なお、本願ではＡＷＳに規定された公称径２．５〜５．０ｍｍの心線を対象とする。被覆径は、溶接棒中央部を直角に交わる２軸の直径をマイクロメータにて測定し、その平均値とした。心線径は、心線中央部を直角に交わる２軸の直径をマイクロメータにて測定し、その平均値とした。 In the present application, a core wire with a nominal diameter of 2.5 to 5.0 mm specified in AWS is targeted. The diameter of the coating was determined by measuring the diameter of two axes perpendicular to the center of the welding rod with a micrometer, and taking the average value. As the core wire diameter, the diameter of two axes intersecting at right angles with the center of the core wire was measured with a micrometer, and the average value was taken.
［被覆剤の密度：０．２００〜０．２６０（ｇ/ｃｍ３）］
被覆剤の密度は、被覆径／心線径が規定を満たさない場合は、０．２００〜０．２６０（ｇ/ｃｍ３）とする。本願において、被覆剤の密度の調整はフラックスの主要構成原料である炭酸塩の粒度を調整することにより行う。すなわち、炭酸塩として粒度の粗い炭酸塩（粒度構成：７５μｍ以下の構成比が４０％，７５μｍを超え１０６μｍ以下の構成比が２０％，１０６μｍを超え１５０μｍ以下の構成比が２０％，１５０μｍ超の構成比が２０％）を多く適用することにより被覆剤の密度を低下させることができ、炭酸塩として粒度の細かい炭酸塩（粒度構成：７５μｍ以下の構成比が１００％）を多く適用することにより被覆剤の密度を上昇させることができる。なお、被覆剤の実際の製品の製造においては、被覆剤中の炭酸塩の粒度のみならず、他のフラックスの粒度によっても影響される。また一般に、塗装時の製造条件として、塗装の圧力が大きい場合には密度も大きく、圧力が小さい場合には密度も小さくなる傾向がある。
[Density of Coating: 0.20-0.260 (g / cm 3 )]
The density of the coating agent is set to 0.200 to 0.260 (g / cm 3 ) when the coating diameter / core diameter does not satisfy the specification. In the present application, the density of the coating agent is adjusted by adjusting the particle size of carbonate which is a main constituent material of the flux. That is, carbonates having a coarse particle size as carbonates (particle composition: composition ratio of 75 μm or less is 40%, composition ratio of more than 75 μm to 106 μm is 20%, composition ratio of 106 μm to 150 μm is 20%, more than 150 μm) The density of the coating agent can be reduced by applying a large proportion of 20%), and by applying a large number of fine particle size carbonates (particle size constitution: 100% of a proportion of 75 μm or less) as carbonates. The density of the coating can be increased. In addition, in manufacture of the actual product of a coating agent, it is influenced not only by the particle size of carbonate in a coating agent but the particle size of another flux. In general, as a manufacturing condition at the time of coating, when the pressure of coating is large, the density is also large, and when the pressure is small, the density tends to be small.
被覆剤の密度が０．２００ｇ/ｃｍ３未満では、被覆棒の塗装性が劣化し、表面の凹凸が激しくなり、被覆棒の外観が劣化する。一方、０．２６０ｇ/ｃｍ３を超えると、被覆剤の放熱性が劣化し棒焼けが発生しやすくなる。そして、棒焼けにより保護筒としての機能が不十分になり、アーク安定性が劣化し、スパッタが増加する。したがって、被覆剤の密度は０．２００〜０．２６０（ｇ/ｃｍ３）とする。
ただし、被覆径／心線径が規定を満たしていれば、被覆剤の密度は前記規定を満たさなくても問題ない。
If the density of the coating agent is less than 0.200 g / cm 3 , the coatability of the coated rod is degraded, the surface irregularities become severe, and the appearance of the coated rod is degraded. On the other hand, when it exceeds 0.260 g / cm 3 , the heat dissipation of the coating material is deteriorated and the burnt rod tends to occur. As a result, the function as a protective cylinder becomes insufficient due to the burning of the rod, the arc stability deteriorates, and the spatter increases. Therefore, the density of the coating agent is set to 0.200 to 0.260 (g / cm 3 ).
However, if the coating diameter / core diameter meets the requirements, the density of the coating does not matter even if it does not meet the requirements.
なお、ここでいう被覆剤の密度ｄは、溶接棒１本当たりの被覆剤の質量をＭｆ、体積をＶｆとすると、
ｄ＝Ｍｆ／Ｖｆ（ｇ／ｃｍ３）で求められる値である。ここで、
Ｍｆ＝Ｍｅ−Ｍｒ（ｇ）
Ｖｆ＝｛（Ｄｅ／２）−（Ｄｒ／２)｝２×π×Ｌ （ｃｍ３）
Ｍｅ：溶接棒単重（ｇ）
Ｍｒ：心線単重（ｇ）
Ｄｅ：被覆径（ｃｍ）
Ｄｒ：心線径（ｃｍ）
Ｌ：被覆長（ｃｍ）
である。
The density d of the coating agent referred to here is Mf and Vf, respectively, where Mf is the mass of the coating agent per welding rod, and
It is a value calculated by d = Mf / Vf (g / cm 3 ). here,
Mf = Me-Mr (g)
Vf = {(De / 2) − (Dr / 2)} 2 × π × L (cm 3 )
Me: Welding rod single weight (g)
Mr: Heart wire single weight (g)
De: Coating diameter (cm)
Dr: Wire diameter (cm)
L: Coating length (cm)
It is.
＜被覆アーク溶接棒の製造方法＞
本発明の被覆アーク溶接棒は、例えば以下のようにして製造することができる。
まず、前記した被覆剤を珪酸ソーダ、珪酸カリで代表される水ガラス等の粘結剤により、鋼心線の周囲に通常の溶接棒塗装機により被覆塗装する。その後、水分を除去するため、４００〜５５０℃で焼成する。
<Method of manufacturing coated arc welding rod>
The coated arc welding rod of the present invention can be manufactured, for example, as follows.
First, the above-mentioned coating is coated with a binder such as water glass represented by sodium silicate, potassium silicate, etc., around a steel core wire by a conventional welding rod coating machine. Then, it bakes at 400-550 degreeC in order to remove a water | moisture content.
以下、本発明の範囲に入る実施例について、その効果を本発明の範囲から外れる比較例と比較して説明する。
心線全質量当たり、Ｃｒを２．０〜１０．０質量％含有する心線の外周に被覆剤を塗布し、表１、２に示す被覆径／心線径、被覆剤の密度、被覆剤中の炭酸塩の種類及び化学成分組成の被覆アーク溶接棒を製造した。得られた各種溶接棒を用いて、Ｃｒ−Ｍｏ鋼板を母材として溶接実験を行い、表３の結果を得た。全供試材（Ｎｏ.１〜２９）について心線径＝３．２ｍｍにて評価したのち、心線径＝３．２ｍｍにて各項目が良好であったものは、心線径＝２．５ｍｍ、４．０ｍｍ及び５．０ｍｍにおいて同様の特性を有することを別途確認している。
The effects of the examples falling within the scope of the present invention will be described below in comparison with comparative examples outside the scope of the present invention.
Coating is applied to the outer periphery of a cord containing 2.0 to 10.0% by mass of Cr based on the total weight of the cord, and the coating diameter / core diameter, coating density, coating shown in Tables 1 and 2 A coated arc welding rod of different carbonate type and chemical composition was prepared. Using the various types of welding rods obtained, welding experiments were performed using a Cr-Mo steel plate as a base material, and the results in Table 3 were obtained. After evaluating all the test materials (No. 1 to 29) with a core wire diameter of 3.2 mm, those in which each item was good at a core wire diameter of 3.2 mm are: core wire diameter = 2. It has been separately confirmed that the same characteristics are obtained at 5 mm, 4.0 mm and 5.0 mm.
溶接条件は以下のとおりである。
[溶接条件]
使用電流：心線径 φ２．５ｍｍ：４０〜１００Ａ
心線径 φ３．２ｍｍ：６０〜１３０Ａ
心線径 φ４．０ｍｍ：８０〜１７０Ａ
心線径 φ５．０ｍｍ：１５０〜２３０Ａ
予熱パス間温度：２００〜２５０℃
溶接姿勢：全姿勢（全供試材（Ｎｏ.１〜２９）について立向上進にて評価したのち、立向上進にて各項目が良好であったものは全姿勢において同様の特性を有することを別途確認している。）
The welding conditions are as follows.
[Welding conditions]
Working current: Core diameter φ 2.5 mm: 40 to 100 A
Core diameter φ 3.2 mm: 60 to 130 A
Core diameter φ 4.0 mm: 80 to 170 A
Wire diameter φ 5.0 mm: 150 to 230 A
Preheating pass temperature: 200 to 250 ° C
Welding posture: All postures (all samples (No. 1 to 29) are evaluated by vertical improvement, and those items that were good by vertical improvement have similar characteristics in all postures) Separately.)
溶接実験において、以下の項目を目視で確認し、官能評価を行った。
［耐棒焼け性］
溶接棒の残り長さが５０ｍｍＬになるまで溶接した時、棒焼けが発生せず保護筒が形成されていたものを○、棒焼けが発生し保護筒が形成されていなかったものを×と評価した。なお、心線の長さは、φ２．５ｍｍが３００ｍｍＬ、φ３．２ｍｍが３５０ｍｍＬ、φ４．０ｍｍ及びφ５．０ｍｍが４００ｍｍＬのものを使用した。
The following items were visually confirmed in a welding test, and sensory evaluation was performed.
[Bar burn resistance]
When welding was performed until the remaining length of the welding rod reached 50 mm L, evaluation was made as ○ when rod burning did not occur and that a protective cylinder was formed as ○, and when rod burning occurred and no protective cylinder was formed as × did. In addition, as for the length of a core wire, the thing of 300 mmL of (phi) 2.5 mm, 350 mmL of (phi) 3.2 mm, and 400 mmL of (phi) 4.0 mm and (phi) 5.0 mm was used.
［スラグ巻込み］
交流、直流いずれの極性においてもスラグ巻込みが発生しないものを○、スラグ巻込みが発生するものを×と評価した。
[Slag inclusion]
In the case of neither alternating current nor direct current polarity, も の was evaluated if slag entrainment did not occur, and x was evaluated if slag entrainment occurred.
［塗装性］
いずれの被覆径においても塗装性が良好であるものを○、良好でないものを×と評価した。
[Paintability]
The paintability of any coating diameter was evaluated as ○, and the poor quality was evaluated as x.
［総合評価］
上記３つの項目のうち、すべての項目が○以上であるものを○、いずれかひとつの項目でも×があるものを×と評価した。
[Comprehensive evaluation]
Of the above three items, those with all items ○ or more were evaluated as ○, and those with any one item with x were evaluated as x.
被覆アーク溶接棒の規定を表１、２に示し、評価結果を表３に示す。なお、表１において、本発明の範囲を満たさないものは数値等に下線を引いて示す。また、表２において、「−」は成分を含有しないものである。また、フラックス成分には、アーク安定剤及びスラグ生成剤（ＭｇＯ等）と、Ｎａ２Ｏ、Ｋ２Ｏ、Ｌｉ２Ｏ等のアルカリ金属酸化物が含まれ、合金成分には、Ｐ及びＳ等の不可避的不純物が含まれる。また、表１の炭酸塩はＣＯ２換算値である。なお、表１、２において、フラックス成分及び合金成分は、溶接棒全質量あたりの含有量である。 The specifications of the coated arc welding rod are shown in Tables 1 and 2, and the evaluation results are shown in Table 3. In Table 1, those that do not satisfy the scope of the present invention are indicated by underlining numerical values and the like. Moreover, in Table 2, "-" is a thing which does not contain an ingredient. Further, the flux component includes an arc stabilizer and a slag forming agent (such as MgO), and an alkali metal oxide such as Na 2 O, K 2 O, and Li 2 O. The alloy component includes P and S, etc. Of inevitable impurities. Moreover, the carbonate in Table 1 is a CO 2 converted value. In Tables 1 and 2, the flux component and the alloy component are contents per total mass of the welding rod.
表１〜３に示すように、Ｎｏ.１〜１８、２７〜２９は本発明の範囲を満たしており、全ての評価項目で良好な結果を得られた。
一方、Ｎｏ.１９〜２６は本発明の範囲を満たしていないため、以下の結果となった。
As shown in Tables 1 to 3, Nos. 1 to 18 and 27 to 29 satisfy the scope of the present invention, and good results were obtained in all the evaluation items.
On the other hand, since Nos. 19 to 26 did not satisfy the scope of the present invention, the following results were obtained.
Ｎｏ.１９は、被覆径／心線径及び被覆剤の密度のいずれも規定を外れた。よって、被覆径／心線径が下限値未満のため、棒焼けが発生した。また、被覆剤の密度が下限値未満のため、塗装性が劣った。
Ｎｏ.２０は、被覆径／心線径及び被覆剤の密度のいずれも規定を外れた。よって、被覆径／心線径が下限値未満かつ被覆剤の密度が上限値を超えるため、棒焼けが発生した。
In No. 19, the coating diameter / core diameter and the density of the coating material were both out of specification. Therefore, rod burning occurred because the coating diameter / core diameter was less than the lower limit value. Moreover, since the density of a coating agent was less than a lower limit, paintability was inferior.
In No. 20, the coating diameter / core diameter and the density of the coating material were both out of specification. Therefore, since the coating diameter / core diameter is less than the lower limit value and the density of the coating material exceeds the upper limit value, rod burn occurred.
Ｎｏ.２１は、被覆径／心線径及び被覆剤の密度のいずれも規定を外れた。よって、被覆径／心線径が上限値を超えるため、スラグ巻込みが発生した。また、被覆剤の密度が下限値未満のため、塗装性が劣った。
Ｎｏ.２２は、被覆径／心線径及び被覆剤の密度のいずれも規定を外れた。よって、被覆径／心線径が上限値を超えるため、スラグ巻込みが発生した。また、被覆剤の密度が上限値を超えるため、棒焼けが発生した。
Ｎｏ.２３〜２６は、被覆剤中に炭酸Ｃａ以外の炭酸塩を含有しているため、棒焼けが発生した。なお、Ｎｏ.２６の炭酸Ｍｇは、０．１質量％を超えるものである。
No. 21 was out of specification both in coating diameter / core diameter and in density of the coating. Accordingly, since the coating diameter / core diameter exceeds the upper limit value, slag inclusion occurs. Moreover, since the density of a coating agent was less than a lower limit, paintability was inferior.
In No. 22, the coating diameter / core diameter and the density of the coating material were both out of specification. Accordingly, since the coating diameter / core diameter exceeds the upper limit value, slag inclusion occurs. Moreover, since the density of the coating material exceeded the upper limit value, stick burning occurred.
Since No. 23-26 contained carbonates other than Ca carbonate in coating agent, stick burning occurred. In addition, Mg carbonate of No. 26 exceeds 0.1 mass%.
なお、本発明は、被覆径／心線径の値、被覆剤の密度、及び、炭酸塩の種類に特徴を有するものであるため、合金成分及びフラックス成分の含有量が規定を外れる比較例は記載していない。これらが規定を外れる場合は、各合金元素の添加理由及び組成限定理由、及び、被覆剤中（フラックス中）の各元素の添加理由及び組成限定理由で説明したとおりである。 In addition, since the present invention is characterized in the value of coating diameter / core diameter, the density of the coating agent, and the type of carbonate, the comparative example in which the content of the alloy component and the flux component deviates from the definition Not listed. When these are out of the specification, they are as explained in the reason for addition of each alloy element and the reason for limitation of the composition, and the reason for addition of each element in the coating agent (in the flux) and the reason for limitation of the composition.
以上、本発明について実施の形態及び実施例を示して詳細に説明したが、本発明の趣旨は前記した内容に限定されることなく、その権利範囲は特許請求の範囲の記載に基づいて広く解釈しなければならない。なお、本発明の内容は、前記した記載に基づいて広く改変・変更等することが可能であることはいうまでもない。 Although the present invention has been described in detail by showing the embodiment and the examples, the scope of the present invention is not limited to the contents described above, and the scope of the right is widely interpreted based on the description of the claims. Must. Needless to say, the contents of the present invention can be widely modified or changed based on the above description.
Claims (4)
Ｃ：０．０１〜０．１５質量％
Ｓｉ：０．５〜１．５質量％
Ｍｎ：０．４〜２．０質量％
Ｃｒ：３．０〜９．０質量％
Ｍｏ：０．０１〜１．５０質量％
Ｆｅ：５５〜７０質量％
を含有し、残部が不可避的不純物であり、
前記低水素系被覆アーク溶接棒の被覆剤中に、前記低水素系被覆アーク溶接棒全質量当たり、フラックス成分として、
炭酸Ｃａ：ＣＯ２換算値で１〜６質量％
金属弗化物：Ｆ換算値で１〜４質量％
ＳｉＯ２：５〜１５質量％
を含有し、
前記被覆剤中に炭酸Ｃａ以外の炭酸塩がＣＯ２換算値で０．１質量％以下含有されており、
前記低水素系被覆アーク溶接棒の直径を被覆径とし、心線の直径を心線径としたときの比である被覆径／心線径が１．５０〜１．８０、及び、前記被覆剤の密度が０．２００〜０．２６０（ｇ／ｃｍ３）のいずれか一方又は両方を満足することを特徴とする低水素系被覆アーク溶接棒。 In the entire low hydrogen-based coated arc welding rod, the alloy component is, per the total mass of the low hydrogen-based coated arc welding rod,
C: 0.01 to 0.15 mass%
Si: 0.5 to 1.5% by mass
Mn: 0.4 to 2.0% by mass
Cr: 3.0 to 9.0 mass%
Mo: 0.01 to 1.50% by mass
Fe: 55 to 70% by mass
Contains the remainder, and the remainder is an unavoidable impurity,
In the coating of the low hydrogen-based coated arc welding rod, as a flux component per total mass of the low hydrogen-based coated arc welding rod,
Carbonation Ca: 1 to 6 mass% in CO 2 conversion value
Metal fluoride: 1 to 4% by mass in F conversion value
SiO 2 : 5 to 15% by mass
Contains
0.1% by mass or less of carbonate other than Ca carbonate is contained in the coating agent in terms of CO 2 conversion value,
The coating diameter / core diameter is 1.50 to 1.80, which is the ratio when the diameter of the low hydrogen-based coated arc welding rod is the coating diameter and the diameter of the core wire is the core diameter, and the coating agent A low hydrogen-based coated arc welding rod characterized in that the density of B satisfies one or both of 0.200 to 0.260 (g / cm 3 ).
前記低水素系被覆アーク溶接棒全体中に、前記低水素系被覆アーク溶接棒全質量当たり、合金成分として、さらに、
Ｎｉ：１．０質量％以下
Ｔｉ：０．５質量％以下
Ｖ：０．５質量％以下
Ｎｂ：０．５質量％以下
を含有することを特徴とする請求項１に記載の低水素系被覆アーク溶接棒。 The content of the Cr is 5.0 to 9.0% by mass based on the total mass of the low hydrogen-based coated arc welding rod,
In the entire low hydrogen-based coated arc welding rod, as the alloy component per total mass of the low hydrogen-based coated arc welding rod,
Ni: 1.0% by mass or less Ti: 0.5% by mass or less V: 0.5% by mass or less Nb: 0.5% by mass or less The low hydrogen-based coating according to claim 1, characterized in that Arc welding rod.
Ｎ：０．１０質量％以下
を含有することを特徴とする請求項１又は請求項２に記載の低水素系被覆アーク溶接棒。 In the entire low hydrogen-based coated arc welding rod, as the alloy component per total mass of the low hydrogen-based coated arc welding rod,
N: 0.10 mass% or less is contained, The low hydrogen-type coated arc welding rod according to claim 1 or 2 characterized by the above-mentioned.
Ｃｏ：２．０質量％以下
Ｗ：２．０質量％以下
を含有することを特徴とする請求項１から請求項３のいずれか一項に記載の低水素系被覆アーク溶接棒。 In the entire low hydrogen-based coated arc welding rod, as the alloy component per total mass of the low hydrogen-based coated arc welding rod,
Co: 2.0 mass% or less W: 2.0 mass% or less The low hydrogen-based coated arc welding rod according to any one of claims 1 to 3, characterized in that
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