JP2014024098A - Melting type flux used for submerged arc welding and welding method using the same - Google Patents
Melting type flux used for submerged arc welding and welding method using the same Download PDFInfo
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Abstract
【課題】ビード形状及びスラグ剥離性が良好な溶融型フラックスを提供する。
【解決手段】サブマージアーク溶接で用いる溶融型フラックスであって、SiＯ2：15〜27質量％、MnＯ：３〜15質量％、TiＯ2：２〜７質量％、CaＯ：10〜25質量％、CaＦ2：15〜35質量％、Al2Ｏ3：10〜25質量％、MgＯ：２〜10質量％、Ｂ2Ｏ3：0.6質量％以下を含有し、残部が不可避的不純物からなるとともに、そのSiＯ2、MnＯ、TiＯ2、CaＯ、CaＦ2、Al2Ｏ3、MgＯの含有量（質量％）をそれぞれ［％SiＯ2］、［％MnＯ］、［％TiＯ2］、［％CaＯ］、［％CaＦ2］、［％Al2Ｏ3］、［％MgＯ］として、ＢＩ＝〔0.5［％MnＯ］＋［％CaＯ］＋［％MgＯ］＋［％CaＦ2］〕÷〔［％SiＯ2］＋0.5（［％TiＯ2］＋［％Al2Ｏ3］）〕が1.3≦ＢＩ≦2.5を満足する溶融型フラックス。
【選択図】なしDisclosed is a melt type flux having good bead shape and slag peelability.
A melt type flux used in submerged arc welding, SiO 2 : 15 to 27% by mass, MnO: 3 to 15% by mass, TiO 2 : 2 to 7% by mass, CaO: 10 to 25% by mass, CaF 2 : 15 to 35% by mass, Al 2 O 3 : 10 to 25% by mass, MgO: 2 to 10% by mass, B 2 O 3 : 0.6% by mass or less, with the balance being inevitable impurities, The contents (mass%) of SiO 2 , MnO, TiO 2 , CaO, CaF 2 , Al 2 O 3 and MgO are [% SiO 2 ], [% MnO], [% TiO 2 ] and [% CaO], respectively. , [% CaF 2 ], [% Al 2 O 3 ], [% MgO], BI = [0.5 [% MnO] + [% CaO] + [% MgO] + [% CaF 2 ]] ÷ [[% A melt type flux in which SiO 2 ] +0.5 ([% TiO 2 ] + [% Al 2 O 3 ])] satisfies 1.3 ≦ BI ≦ 2.5.
[Selection figure] None
Description
本発明は、サブマージアーク溶接に好適な溶融型フラックス、およびそれを用いた溶接方法に関するもので、特にラインパイプ，原油タンク，ＬＰＧタンク等に用いられる高張力鋼をサブマージアーク溶接する際に好適に用いられ、溶接後の水素起因の割れを生じることなく、ビード形状が優れ、スラグ剥離性と作業性が良好で、溶接金属の酸素量が低く、溶接金属の低温靭性が向上する溶融型フラックス、および溶接方法に関するものである。 The present invention relates to a melt-type flux suitable for submerged arc welding and a welding method using the same, and particularly suitable for submerged arc welding of high-strength steel used in line pipes, crude oil tanks, LPG tanks, and the like. Used, without causing hydrogen-induced cracking after welding, bead shape, excellent slag peelability and workability, low oxygen content of the weld metal, low temperature toughness of the weld metal, And a welding method.
ラインパイプや各種タンク等に用いられるＵＯＥ鋼管，鋼材の自動溶接技術として、ＭＩＧ溶接，ＣＯ2溶接，サブマージアーク溶接が従来から知られている。その中でもサブマージアーク溶接は、高能率で施工でき、かつ高性能な溶接金属を得ることができる溶接技術として広く採用されている。
サブマージアーク溶接で用いるフラックスは、溶融型フラックスと焼成型フラックスがある。溶融型フラックスは、種々の鉱物質を原材料として1200℃以上の高温度で溶融し、冷却して固化した後、さらに粉末状に粉砕したものであり、吸湿し難く、かつ取扱いや保管が容易であるという利点を持つ。一方で、焼成型フラックスは、原材料に結合剤（たとえば水ガラス等）を少量加えて造粒した後、約600℃で焼成したものであり、溶接金属の組成を容易に調節できるという利点を有するが、反面、吸湿し易いという欠点を持つ。
MIG welding, CO 2 welding, and submerged arc welding are conventionally known as automatic welding techniques for UOE steel pipes and steel materials used in line pipes and various tanks. Among them, submerged arc welding is widely adopted as a welding technique that can be applied with high efficiency and can obtain a high-performance weld metal.
Flux used in submerged arc welding includes molten flux and fired flux. The melt-type flux is made by melting various minerals at a high temperature of 1200 ° C or higher, cooling and solidifying it, and then crushing it into a powder. It is difficult to absorb moisture and is easy to handle and store. Has the advantage of being. On the other hand, the calcining type flux is obtained by adding a small amount of a binder (for example, water glass) to the raw material, granulating it, and calcining at about 600 ° C., and has the advantage that the composition of the weld metal can be easily adjusted. However, on the other hand, it has the disadvantage of being easy to absorb moisture.
溶融型フラックスと焼成型フラックスは、いずれも溶接部を大気から遮断して溶接金属の酸化，窒化を防止するとともに、溶融メタルとの冶金反応によって短時間で清浄な溶接金属を形成する等、サブマージアーク溶接にて重要な機能を果たす。
とりわけ溶融型フラックスは、多電極の高速溶接に適しており、かつ溶接金属中の酸素量を低減でき、良好なビード外観が得られるので、ラインパイプ用のＵＯＥ鋼管のように高速溶接性とともに厳しい機械的性質が要求される場合に、使用されることが多い。
Both melt-type flux and fired-type flux are submerged such that the weld is shielded from the atmosphere to prevent oxidation and nitridation of the weld metal, and a clean weld metal is formed in a short time by metallurgical reaction with the molten metal. It plays an important function in arc welding.
In particular, the melt-type flux is suitable for high-speed welding of multi-electrodes, and can reduce the amount of oxygen in the weld metal and provide a good bead appearance. Therefore, it is severe with high-speed weldability like UOE steel pipes for line pipes. Often used when mechanical properties are required.
溶融型フラックスの組成を調節して、溶接金属中の酸素量を低減すれば、溶接金属の靭性を高めることができ、溶融型フラックスの組成を調節する一つの手段として、塩基度を上げる方法が知られている。しかし、単に溶融型フラックスの塩基度を上げるだけでは、溶接金属の酸素量をある程度低減できるものの、良好なビード形状が得られないし、しかも溶接スラグの剥離性が劣化する等の問題が残る。 By adjusting the composition of the melt-type flux and reducing the amount of oxygen in the weld metal, the toughness of the weld metal can be increased. As one means of adjusting the composition of the melt-type flux, there is a method of increasing the basicity. Are known. However, by simply increasing the basicity of the molten flux, the oxygen content of the weld metal can be reduced to some extent, but a good bead shape cannot be obtained, and problems such as deterioration of the peelability of the weld slag remain.
この問題を解決するために、高塩基度の溶融型フラックスが種々提案されている（たとえば特許文献１〜４）。特許文献１〜４に開示された溶融型フラックスは、いずれも成分を規定し、さらに粒度等を規定することによって、溶接金属の靭性向上を達成するとともに、溶接作業を改善するものである。
また、ラインパイプの高強度化のニーズが高まっていることから、厚肉高強度のＵＯＥ鋼管の需要が増加しているが、高張力鋼の溶接によって形成される溶接金属は、溶接後に水素起因の割れ感受性が高まるので、溶接金属の低水素化を図る必要がある。そのため、高張力鋼のサブマージアーク溶接では、溶接金属の低水素化のみならず、上記したように低酸素化を達成できる溶融型フラックスを使用する必要がある。
In order to solve this problem, various melt fluxes with high basicity have been proposed (for example, Patent Documents 1 to 4). The melt-type fluxes disclosed in Patent Documents 1 to 4 all define the components and further define the particle size and the like, thereby improving the toughness of the weld metal and improving the welding operation.
In addition, the need for high-strength UOE steel pipes is increasing due to increasing needs for high-strength line pipes, but the weld metal formed by welding high-strength steel is caused by hydrogen after welding. Therefore, it is necessary to reduce the weld metal hydrogen. Therefore, in the submerged arc welding of high-tensile steel, it is necessary to use a molten flux that can achieve not only lowering of the weld metal but also lowering of oxygen as described above.
ところが溶接金属の低酸素化を達成するために高塩基度の溶融型フラックスを使用すると、溶接金属の水素量が増加する傾向が強くなる。これは、溶融型フラックスの塩基度の上昇によって、スラグ中のCa4Ｆ2Si2Ｏ7（以下、Cuspidineという）が増加することが原因である。つまりCuspidineは、CaＯ、CaＦ2、SiＯ2からなる化合物であり、高温で溶解するときに、結晶構造内に水素を取込み易い物質であるから、スラグ中のCuspidineの増加に伴って、溶接金属の水素量が増加すると考えられる。 However, when a high-basic molten flux is used to achieve low oxygen content in the weld metal, the tendency for the hydrogen content of the weld metal to increase increases. This is because Ca 4 F 2 Si 2 O 7 (hereinafter referred to as Cuspidine) in the slag increases as the basicity of the molten flux increases. In other words, Cuspidine is a compound composed of CaO, CaF 2 , and SiO 2 , and is a substance that easily incorporates hydrogen into the crystal structure when dissolved at high temperatures. Therefore, as the amount of Cuspidine in the slag increases, It is thought that the amount of hydrogen increases.
耐サワー環境で使用されるラインパイプは、溶接部の硬化性を下げる（すなわち靭性を高める）ために溶接金属中の合金元素量を低く抑える必要があり、かつ酸素量も低減する必要がある。また、ビードの形状、スラグの剥離性、溶接施工の作業性は、溶接金属中の酸素量を低減しながら、改善する必要がある。
一方で、高強度ラインパイプは、溶接金属の低温割れ（すなわち水素起因の割れ）感受性を抑えるために、溶接金属中の水素量を低減する必要がある。
In a line pipe used in a sour-resistant environment, it is necessary to keep the amount of alloying elements in the weld metal low in order to reduce the hardenability of the welded portion (that is, increase the toughness), and it is also necessary to reduce the amount of oxygen. In addition, the bead shape, slag peelability, and welding workability need to be improved while reducing the amount of oxygen in the weld metal.
On the other hand, the high-strength line pipe needs to reduce the amount of hydrogen in the weld metal in order to suppress the sensitivity of the weld metal to low-temperature cracking (that is, cracking due to hydrogen).
ところが、溶接金属中の酸素量の低減と水素量の低減とを併せて可能にする溶融型フラックスは、未だ開発されていない。
そこで本発明は、ラインパイプ等の高い靭性が要求される溶接金属を形成するためのサブマージアーク溶接にて、溶接金属の低酸素化と低水素化とを達成でき、しかもビードの形状およびスラグの剥離性も良好な溶融型フラックスを提供することを目的とする。
However, a melt-type flux that enables both a reduction in the amount of oxygen in the weld metal and a reduction in the amount of hydrogen has not been developed yet.
Therefore, the present invention can achieve low oxygen and low hydrogen of the weld metal in submerged arc welding for forming a weld metal that requires high toughness such as a line pipe, and further, the bead shape and slag can be achieved. The object is to provide a melt-type flux with good releasability.
発明者らは、上記の課題を解決するために鋭意検討を行なった結果、溶接金属の低酸素化のためには、溶融型フラックスの塩基度を所定の値に規定する必要があり、溶接金属の低水素化のためには、Cuspidineの晶出を抑える溶融型フラックスを使用する必要があることを見出した。
つまり溶接金属の低水素化を図るためには、Cuspidineが初晶でスラグ中に大量に晶出するのを防ぐとともに、初晶スピネルの晶出も低減する必要がある。その理由は、スピネルが初晶でスラグ中に多量に晶出すると、初晶スピネルの周囲にCuspidineが引き続き晶出するからである。したがって、スピネルの晶出量に影響を及ぼすAl2Ｏ3とMgＯの量を制限した溶融型フラックスを使用する必要がある。
As a result of intensive studies to solve the above-mentioned problems, the inventors need to define the basicity of the molten flux to a predetermined value in order to reduce the oxygen content of the weld metal. It has been found that it is necessary to use a melt type flux that suppresses crystallization of Cuspidine in order to reduce the hydrogen content of.
In other words, in order to reduce the hydrogen content of the weld metal, it is necessary to prevent Cuspidine from being crystallized in the slag as primary crystals and to reduce the crystallization of primary spinels. The reason is that if the spinel is primary and crystallizes in a large amount in the slag, Cuspidine continues to crystallize around the primary spinel. Therefore, it is necessary to use a melt type flux in which the amount of Al 2 O 3 and MgO that affect the amount of spinel crystallization is limited.
本発明は、このような知見に基づいてなされたものである。
なお本発明では、溶接金属の酸素量、溶接施工の作業性、ビードの形状のバランスをとる上で、塩基度として下記の(1)式で算出されるＢＩ値を用いる。
すなわち本発明は、サブマージアーク溶接で用いる溶融型フラックスであって、SiＯ2：15〜27質量％、MnＯ：３〜15質量％、TiＯ2：２〜７質量％、CaＯ：10〜25質量％、CaＦ2：15〜35質量％、Al2Ｏ3：10〜25質量％、MgＯ：２〜10質量％、Ｂ2Ｏ3：0.6質量％以下を含有し、残部が不可避的不純物からなるとともに、そのSiＯ2、MnＯ、TiＯ2、CaＯ、CaＦ2、Al2Ｏ3、MgＯの含有量（質量％）をそれぞれ［％SiＯ2］、［％MnＯ］、［％TiＯ2］、［％CaＯ］、［％CaＦ2］、［％Al2Ｏ3］、［％MgＯ］として、下記の(1)式で算出されるＢＩ値が1.3≦ＢＩ≦2.5を満足する溶融型フラックスである。
ＢＩ＝〔0.5［％MnＯ］＋［％CaＯ］＋［％MgＯ］＋［％CaＦ2］〕÷
〔［％SiＯ2］＋0.5（［％TiＯ2］＋［％Al2Ｏ3］）〕 ・・・(1)
本発明の溶融型フラックスは、［％Al2Ｏ3］と［％MgＯ］が、（［％Al2Ｏ3］＋［％MgＯ］）≦30を満足することが好ましい。
The present invention has been made based on such knowledge.
In the present invention, the BI value calculated by the following equation (1) is used as the basicity in order to balance the oxygen content of the weld metal, the workability of the welding work, and the bead shape.
That is, the present invention is a melt-type flux used in submerged arc welding, and includes SiO 2 : 15 to 27% by mass, MnO: 3 to 15% by mass, TiO 2 : 2 to 7% by mass, CaO: 10 to 25% by mass. , CaF 2 : 15 to 35% by mass, Al 2 O 3 : 10 to 25% by mass, MgO: 2 to 10% by mass, B 2 O 3 : 0.6% by mass or less, with the balance being inevitable impurities , The contents (mass%) of SiO 2 , MnO, TiO 2 , CaO, CaF 2 , Al 2 O 3 , and MgO are [% SiO 2 ], [% MnO], [% TiO 2 ], [% CaO, respectively. ], [% CaF 2 ], [% Al 2 O 3 ], and [% MgO], it is a melt type flux in which the BI value calculated by the following formula (1) satisfies 1.3 ≦ BI ≦ 2.5.
BI = [0.5 [% MnO] + [% CaO] + [% MgO] + [% CaF 2 ]] ÷
[[% SiO 2 ] +0.5 ([% TiO 2 ] + [% Al 2 O 3 ])] (1)
In the melt type flux of the present invention, it is preferable that [% Al 2 O 3 ] and [% MgO] satisfy ([% Al 2 O 3 ] + [% MgO]) ≦ 30.
また本発明は、上記した溶融型フラックスを用いて、溶接入熱２〜10kJ／mmでサブマージアーク溶接を行ない、スラグ内の初晶スピネルの晶出量を面積分率で10％以下とするサブマージアーク溶接方法である。 In addition, the present invention performs submerged arc welding with a welding heat input of 2 to 10 kJ / mm using the above-described molten type flux, so that the crystallization amount of primary spinel in the slag is 10% or less in area fraction. This is an arc welding method.
本発明によれば、厳しい環境で使用されるラインパイプや各種タンクのサブマージアーク溶接において、靭性が高くかつ水素起因の割れが生じない溶接金属が得られ、しかも優れた形状のビードが形成される。さらに溶接施工の作業性も良好であるから、産業上格段の効果を奏する。 According to the present invention, in submerged arc welding of line pipes and various tanks used in harsh environments, a weld metal having high toughness and free of hydrogen-induced cracks can be obtained, and an excellently shaped bead is formed. . Furthermore, since the workability of welding construction is also good, it has a remarkable industrial effect.
まず、本発明の溶融型フラックスの成分について説明する。
(a)SiＯ2
SiＯ2は、スラグをガラス化させるとともに、ビードの外観および溶接金属の靭性に多大な影響を及ぼす重要な成分である。溶融型フラックスのSiＯ2の含有量が15質量％未満では、十分な幅のビードが形成されず、ビードの形状が劣る。一方、27質量％を超えると、良好な形状のビードが形成されるが、溶接金属の酸素量が増加して靭性の劣化を招く。したがって、溶融型フラックスのSiＯ2の含有量は15〜27質量％の範囲内とした。
First, the components of the melt type flux of the present invention will be described.
(a) SiO 2
SiO 2 is an important component that vitrifies the slag and has a great influence on the appearance of the bead and the toughness of the weld metal. When the content of SiO 2 in the molten flux is less than 15% by mass, a sufficiently wide bead is not formed, and the bead shape is inferior. On the other hand, if it exceeds 27 mass%, a bead having a good shape is formed, but the oxygen content of the weld metal is increased, resulting in deterioration of toughness. Therefore, the content of SiO 2 in the melt type flux is set in the range of 15 to 27% by mass.
(b)MnＯ
MnＯは、スラグの流動性を向上させ、ビードの形状を滑らかにする成分である。溶融型フラックスのMnＯの含有量が３質量％未満では、その効果が得られない。一方、15質量％を超えると、溶接金属の酸素量が増加して靭性の劣化を招く。したがって、溶融型フラックスのMnＯの含有量は３〜15質量％の範囲内とした。
(b) MnO
MnO is a component that improves the fluidity of the slag and smoothes the bead shape. If the MnO content of the molten flux is less than 3% by mass, the effect cannot be obtained. On the other hand, if it exceeds 15% by mass, the oxygen content of the weld metal increases, leading to deterioration of toughness. Therefore, the content of MnO in the molten flux is set in the range of 3 to 15% by mass.
(c)TiＯ2
TiＯ2は、スラグの剥離性に影響を及ぼす成分である。溶融型フラックスのTiＯ2の含有量が２質量％未満では、スラグの剥離性が改善されず、ビードに焼付きやすくなる。一方、７質量％を超えると、良好な形状のビードが得られない。したがって、溶融型フラックスのTiＯ2の含有量は２〜７質量％の範囲内とした。
(c) TiO 2
TiO 2 is a component that affects the slag peelability. When the content of TiO 2 in the molten flux is less than 2% by mass, the slag releasability is not improved and the beads are easily seized. On the other hand, when it exceeds 7 mass%, a bead having a good shape cannot be obtained. Therefore, the content of TiO 2 in the molten flux is set in the range of 2 to 7% by mass.
(d)CaＯ
CaＯは、溶融型フラックスの塩基度（ＢＩ値）を高めて、溶接金属の酸素量を低減することによって、溶接金属の靭性を向上させる成分である。溶融型フラックスのCaＯの含有量が10質量％未満では、塩基度が低くなり、溶接金属の靭性が劣化すると同時に、ビードの形状が劣る。一方、25質量％を超えると、ビードの表面にあばた等の欠陥が生じやすくなる。したがって、溶融型フラックスのCaＯの含有量は10〜25質量％の範囲内とした。
(d) CaO
CaO is a component that improves the toughness of the weld metal by increasing the basicity (BI value) of the molten flux and reducing the oxygen content of the weld metal. When the CaO content of the molten flux is less than 10% by mass, the basicity is lowered, the toughness of the weld metal is deteriorated, and the bead shape is inferior. On the other hand, if it exceeds 25% by mass, defects such as flapping are likely to occur on the surface of the bead. Therefore, the content of CaO in the melt type flux is set in the range of 10 to 25% by mass.
(e)CaＦ2
CaＦ2は、溶接金属の酸素量を低減して靭性の向上させる成分である。溶融型フラックスのCaＦ2の含有量が15質量％未満では、その効果が得られない。一方、35質量％を超えると、スラグが剥離しにくくなる。したがって、溶融型フラックスのCaＦ2の含有量は15〜35質量％の範囲内とした。
(e) CaF 2
CaF 2 is a component that reduces the oxygen content of the weld metal and improves toughness. If the CaF 2 content of the molten flux is less than 15% by mass, the effect cannot be obtained. On the other hand, when it exceeds 35 mass%, it becomes difficult to peel off the slag. Therefore, the content of CaF 2 in the melt type flux is set in the range of 15 to 35% by mass.
(f)Al2Ｏ3
Al2Ｏ3は、スラグのガラス化を促進して、溶接金属の水素量を低減させる成分である。溶融型フラックスのAl2Ｏ3含有量が10質量％未満では、その効果が得られない。一方、25質量％を超えると、溶融型フラックスの融点が高くなりすぎて、良好な形状のビードが得られない。したがって、溶融型フラックスのAl2Ｏ3の含有量は10〜25質量％の範囲内とした。
(f) Al 2 O 3
Al 2 O 3 is a component that promotes the vitrification of slag and reduces the amount of hydrogen in the weld metal. If the Al 2 O 3 content of the molten flux is less than 10% by mass, the effect cannot be obtained. On the other hand, if it exceeds 25 mass%, the melting point of the melt-type flux becomes too high, and a bead having a good shape cannot be obtained. Therefore, the content of Al 2 O 3 in the melt type flux is set in the range of 10 to 25% by mass.
(g)MgＯ
MgＯは、溶融型フラックスの塩基度（ＢＩ値）を高めるために必要な成分である。溶融型フラックスのMgＯの含有量が２質量％未満では、塩基度が低くなり、溶接金属の靭性が劣化する。一方、10質量％を超えると、溶融型フラックスの融点が高くなりすぎて、良好な形状のビードが得られない。したがって、溶融型フラックスのMgＯの含有量は２〜10質量％の範囲内とした。
(g) MgO
MgO is a component necessary for increasing the basicity (BI value) of the molten flux. When the content of MgO in the molten flux is less than 2% by mass, the basicity becomes low and the toughness of the weld metal deteriorates. On the other hand, if it exceeds 10% by mass, the melting point of the melt-type flux becomes too high and a bead having a good shape cannot be obtained. Therefore, the content of MgO in the melt type flux is set in the range of 2 to 10% by mass.
(h)Ｂ2Ｏ3
Ｂは、溶接時に溶接金属内に入り、均一な微細フェライトからなる溶接金属を形成する作用を有する元素であり、溶融型フラックスにＢ2Ｏ3として添加する。溶融型フラックスのＢ2Ｏ3の含有量が0.6質量％を超えると、スラグが剥離しにくくなり、かつ溶接金属に割れが発生しやすくなる。したがって、溶融型フラックスのＢ2Ｏ3の含有量は0.6質量％以下とした。
(h) B 2 O 3
B is an element having an action of entering into the weld metal at the time of welding and forming a weld metal composed of uniform fine ferrite, and is added to the molten flux as B 2 O 3 . If the content of B 2 O 3 in the melt type flux exceeds 0.6 mass%, the slag becomes difficult to peel off and cracks are likely to occur in the weld metal. Therefore, the content of B 2 O 3 in the molten flux is set to 0.6% by mass or less.
次に、上記した成分の相互作用について説明する。なお、溶融型フラックスのSiＯ2，MnＯ，TiＯ2，CaＯ，CaＦ2，Al2Ｏ3，MgＯの含有量（質量％）を、それぞれ［％SiＯ2］、［％MnＯ］、［％TiＯ2］、［％CaＯ］、［％CaＦ2］、［％Al2Ｏ3］、［％MgＯ］と記す。
(i)［％Al2Ｏ3］＋［％MgＯ］
溶融型フラックスのAl2Ｏ3とMgＯの合計の含有量が増大すると初晶スピネルが晶出しやすくなり、［％Al2Ｏ3］＋［％MgＯ］が30を超えると、初晶スピネルの周囲にCuspidineが晶出する。その結果、溶接金属の水素量の増大を招く。したがって、［％Al2Ｏ3］＋［％MgＯ］≦30とする。
Next, the interaction of the above components will be described. Note that the contents (mass%) of SiO 2 , MnO, TiO 2 , CaO, CaF 2 , Al 2 O 3 , and MgO in the molten flux are [% SiO 2 ], [% MnO], and [% TiO 2, respectively. ], [% CaO], [% CaF 2 ], [% Al 2 O 3 ], [% MgO].
(i) [% Al 2 O 3 ] + [% MgO]
When the total content of molten flux Al 2 O 3 and MgO increases, the primary spinel becomes easier to crystallize, and when [% Al 2 O 3 ] + [% MgO] exceeds 30, the surroundings of the primary spinel Cuspidine crystallizes out. As a result, the amount of hydrogen in the weld metal is increased. Therefore, [% Al 2 O 3 ] + [% MgO] ≦ 30.
(j)塩基度（ＢＩ値）
本発明では、溶接金属の酸素量、溶接施工の作業性、ビードの形状のバランスを精度良く評価するために、塩基度として下記の(1)式で算出されるＢＩ値を用いる。ＢＩ値が1.3未満では、溶接金属の酸素量が高くなり、溶接金属の機械的性質、とりわけ低温靭性が劣化する。一方、2.5を超えると、ビードの形状が悪くなり、かつスラグの剥離性も極端に悪くなる。したがって、1.3≦ＢＩ≦2.5とする。
ＢＩ＝〔0.5［％MnＯ］＋［％CaＯ］＋［％MgＯ］＋［％CaＦ2］〕÷
〔［％SiＯ2］＋0.5（［％TiＯ2］＋［％Al2Ｏ3］）〕 ・・・(1)
本発明の溶融型フラックスの成分は、上記の(a)〜(h)で説明した通りであるが、LiＯ2、Na2Ｏ、Ｋ2Ｏ、BaＯ、ZrＯ2の１種または２種以上を合計２質量％以下の範囲で含有しても良い。これらの成分のうち、LiＯ2、Na2Ｏ、Ｋ2Ｏはアーク安定化の効果を有する成分、BaＯ、ZrＯ2はスラグ粘度を増加する作用を有する成分であり、上記の(i)(j)で説明した成分の相互作用には影響しない。
(j) Basicity (BI value)
In the present invention, in order to accurately evaluate the balance between the oxygen content of the weld metal, the workability of the welding work, and the bead shape, the BI value calculated by the following equation (1) is used as the basicity. If the BI value is less than 1.3, the amount of oxygen in the weld metal becomes high, and the mechanical properties of the weld metal, particularly the low temperature toughness, deteriorate. On the other hand, when it exceeds 2.5, the shape of the bead is deteriorated, and the slag removability is extremely deteriorated. Therefore, 1.3 ≦ BI ≦ 2.5.
BI = [0.5 [% MnO] + [% CaO] + [% MgO] + [% CaF 2 ]] ÷
[[% SiO 2 ] +0.5 ([% TiO 2 ] + [% Al 2 O 3 ])] (1)
Component of melt flux of the present invention is as described in the above (a) ~ (h), LiO 2, Na 2 O, K 2 O, BaO, 1 kind of ZrO 2 or two or more You may contain in the range of 2 mass% or less in total. Among these components, LiO 2 , Na 2 O and K 2 O are components having an effect of stabilizing the arc, and BaO and ZrO 2 are components having an action of increasing the slag viscosity, and the above (i) (j It does not affect the interaction of the components described in).
また溶融型フラックスの粒度は、特に限定しないが、搬送に伴う凝集や飛散を防止する、あるいは溶接施工の際に溶融しやすくかつ溶融メタルとの冶金反応を促進する観点から、36〜200meshの粒子が60％以上である粒度分布が望ましい。
次に、上記した溶融型フラックスを用いてサブマージアーク溶接を行なう溶接方法について説明する。
In addition, the particle size of the melt-type flux is not particularly limited, but it is 36 to 200 mesh particles from the viewpoint of preventing agglomeration and scattering accompanying conveyance, or being easily melted during welding and promoting the metallurgical reaction with the molten metal. A particle size distribution in which is 60% or more is desirable.
Next, a welding method for performing submerged arc welding using the above-described molten flux will be described.
電極の数は特に限定しない。通常のサブマージアーク溶接で用いる電極（たとえば４電極等）であれば、支障なく適用できる。
溶接入熱は、合計２〜10kJ／mmの範囲内とする。溶接入熱を２〜10kJ／mmとして溶接を行なうことによって、スラグにおけるCuspidineの晶出を抑え、ひいては初晶スピネルの晶出を低減することができる。
The number of electrodes is not particularly limited. Any electrode (for example, four electrodes) used in normal submerged arc welding can be applied without any problem.
The total welding heat input is in the range of 2 to 10 kJ / mm. By performing welding with a welding heat input of 2 to 10 kJ / mm, crystallization of Cuspidine in the slag can be suppressed, and thus crystallization of primary spinel can be reduced.
このようにして、上記した溶融型フラックスを用いて、上記した方法でサブマージアーク溶接を行なうことによって、スラグにおける初晶スピネルの晶出を低減し、初晶スピネルの面積分率を10％以下に抑えることができる。なお初晶スピネルの面積分率は、溶接進行方向に垂直な任意の断面に占めるスラグの面積に対する初晶スピネルの面積の比率である。 In this way, by performing submerged arc welding by the above-described method using the above-described melt type flux, crystallization of primary spinel in the slag is reduced, and the area fraction of primary spinel is reduced to 10% or less. Can be suppressed. The area fraction of primary spinel is the ratio of the area of primary spinel to the area of slag in any cross section perpendicular to the welding progress direction.
表１に示す成分の溶融型フラックスを用いて、サブマージアーク溶接を行ない、スラグの剥離性、ビードの表面形状、溶接金属中の酸素量、溶接金属の初晶スピネル面積分率を評価した。その手順を以下に説明する。 Submerged arc welding was performed using the melt type flux of the components shown in Table 1, and the slag peelability, the bead surface shape, the oxygen content in the weld metal, and the primary spinel area fraction of the weld metal were evaluated. The procedure will be described below.
厚さ15mmのＡＰＩ−５Ｌ−ＰＳＬ２−Ｘ６５Ｍ鋼板に、角度90°、深さ６mmのＶ溝加工を施し、0.05Ｃ−２Mn系ワイヤと0.18Ｃ−1.55Mn−0.5Mo系ワイヤを組み合わせた４電極サブマージアーク溶接法により、溶接速度235cm／分、溶接入熱3.4kJ／mmで片面一層溶接を行なった。ワイヤ径は、いずれも4.0mmとし、溶接電流／電圧は、第１極（すなわち溶接進行方向の先頭）から順に、1230Ａ／34Ｖ、870Ａ／36Ｖ、750Ａ／42Ｖ、680Ａ／42Ｖとした。 4-electrode with 15mm thick API-5L-PSL2-X65M steel plate with 90 ° angle and 6mm depth V-groove processing combined with 0.05C-2Mn wire and 0.18C-1.55Mn-0.5Mo wire Single-sided single-layer welding was performed by a submerged arc welding method at a welding speed of 235 cm / min and a welding heat input of 3.4 kJ / mm. The wire diameters were all 4.0 mm, and the welding current / voltage were 1230 A / 34 V, 870 A / 36 V, 750 A / 42 V, and 680 A / 42 V in order from the first pole (that is, the head in the welding progress direction).
このようにしてサブマージアーク溶接を行なった後、スラグの剥離性を評価するために、溶接金属表面のスラグの除去処理を行ない、その際に容易に除去できたものを良好（○）、機械的な衝撃を繰り返し与えないと除去できなかったものを不良（×）とした。また、ビード表面を目視で観察して表面形状を評価し、ビード表面がざらついて光沢の少ないもの、あるいはビードの中央に凹部が認められるものを不良（×）、光沢があり、凹部が認められないものを良好（○）とした。溶接金属中の酸素量は、融解−赤外線吸収法によって測定した。スラグの初晶スピネル面積分率は、溶接方向に垂直なスラグ断面のＳＥＭ観察により評価した。それらの結果は表２に示す通りである。 After performing submerged arc welding in this way, in order to evaluate the slag releasability, the slag on the surface of the weld metal was removed, and what was easily removed at that time was good (○), mechanical Those that could not be removed without repeated repeated impacts were defined as defective (x). Also, the surface of the bead is visually observed to evaluate the surface shape. If the bead surface is rough and less glossy, or if a concave portion is observed in the center of the bead, it is defective (x), glossy, and concave portion is recognized. Nothing was judged as good (◯). The amount of oxygen in the weld metal was measured by the melting-infrared absorption method. The primary spinel area fraction of slag was evaluated by SEM observation of the slag cross section perpendicular to the welding direction. The results are as shown in Table 2.
次に、厚さ15mmのＡＰＩ−５Ｌ−ＰＳＬ２−Ｘ６５Ｍ鋼板に、角度90°、深さ６mmのＶ溝加工を施し、0.05Ｃ−２Mn系ワイヤを用いて30℃−72％ＲＨの雰囲気中で１電極サブマージアーク溶接法により、溶接速度50cm／分、溶接電流500Ａ、溶接電圧32Ｖで片面一層溶接を行なった。
このようにしてサブマージアーク溶接を行なった後、ＪＩＳ規格Z3118に準拠してガスクロ法で、溶接金属の拡散性水素量を測定した。その結果を表２に示す。
Next, an API-5L-PSL2-X65M steel plate with a thickness of 15 mm was subjected to V-groove processing at an angle of 90 ° and a depth of 6 mm, and in an atmosphere of 30 ° C.-72% RH using 0.05C-2Mn wire. One-sided single-layer welding was performed at a welding speed of 50 cm / min, a welding current of 500 A, and a welding voltage of 32 V by the one-electrode submerged arc welding method.
After performing submerged arc welding in this way, the amount of diffusible hydrogen in the weld metal was measured by gas chromatography in accordance with JIS standard Z3118. The results are shown in Table 2.
表２から明らかなように、発明例の溶融型フラックスは、いずれの評価因子についても良好な結果が得られた。 As is clear from Table 2, the melt type flux of the inventive example gave good results for any evaluation factor.
Claims (3)
ＢＩ＝〔0.5［％MnＯ］＋［％CaＯ］＋［％MgＯ］＋［％CaＦ2］〕÷
〔［％SiＯ2］＋0.5（［％TiＯ2］＋［％Al2Ｏ3］）〕 ・・・(1) A melt flux for use in submerged arc welding, SiO 2: 15 to 27 wt%, MnO: 3 to 15 wt%, TiO 2: 2~7 wt%, CaO: 10 to 25 wt%, CaF 2: 15 35 wt%, Al 2 O 3: 10~25 wt%, MgO: 2 to 10 wt%, B 2 O 3: containing 0.6 wt% or less, with the balance being unavoidable impurities, wherein the SiO 2, The contents (% by mass) of the MnO, the TiO 2 , the CaO, the CaF 2 , the Al 2 O 3 , and the MgO are [% SiO 2 ], [% MnO], [% TiO 2 ], [% Melting characterized in that the BI value calculated by the following formula (1) satisfies 1.3 ≦ BI ≦ 2.5 as [CaO], [% CaF 2 ], [% Al 2 O 3 ], and [% MgO]. Mold flux.
BI = [0.5 [% MnO] + [% CaO] + [% MgO] + [% CaF 2 ]] ÷
[[% SiO 2 ] +0.5 ([% TiO 2 ] + [% Al 2 O 3 ])] (1)
Submerged arc welding is performed at a welding heat input of 2 to 10 kJ / mm using the melt type flux according to claim 1 or 2, and the amount of primary spinel in the slag is reduced to an area fraction of 10% or less. A submerged arc welding method characterized by that.
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| JP2016022503A (en) * | 2014-07-18 | 2016-02-08 | 株式会社神戸製鋼所 | Narrow groove tandem submerged arc welding method |
| JP2017070955A (en) * | 2015-10-05 | 2017-04-13 | 新日鐵住金株式会社 | Fused flux for submerged arc welding |
| JP2022516181A (en) * | 2019-01-03 | 2022-02-24 | 南京鋼鉄股▲ふん▼有限公司 | Welding wires and methods for submerged arc welding of high manganese low temperature steel |
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| JP2015166100A (en) * | 2014-03-03 | 2015-09-24 | 新日鐵住金株式会社 | Melting type flux for submerged arc welding |
| JP2016022503A (en) * | 2014-07-18 | 2016-02-08 | 株式会社神戸製鋼所 | Narrow groove tandem submerged arc welding method |
| JP2017070955A (en) * | 2015-10-05 | 2017-04-13 | 新日鐵住金株式会社 | Fused flux for submerged arc welding |
| JP2022516181A (en) * | 2019-01-03 | 2022-02-24 | 南京鋼鉄股▲ふん▼有限公司 | Welding wires and methods for submerged arc welding of high manganese low temperature steel |
| JP7193650B2 (en) | 2019-01-03 | 2022-12-20 | 南京鋼鉄股▲ふん▼有限公司 | Welding wire and welding method for submerged arc welding of high manganese low temperature steel |
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