JP3577995B2 - Manufacturing method of fired flux for submerged arc welding - Google Patents

Description

【００１６】
【表２】

【００１７】
フラックス焼成時の昇温速度が溶接ビード外観と密接な関係がある理由としては、次のようなことが考えられる。
通常、脱酸を目的として高温焼成型フラックスに添加される金属粉としては、Ｆｅ−ＳｉおよびＳｉ−Ｍｎが一般に知られているが、これらも ７００℃以上の温度域では、反応速度は遅いものの、徐々に変質（酸化）して脱酸剤としての作用効果が減退する。この点、 ７００℃以上の温度域における昇温速度を５℃／ｍｉｎ以上にすると、最高温度付近での脱酸剤の酸化速度に影響を及ぼすような脱酸剤酸化挙動に変化（昇温時の酸化量が少なく、またその酸化進行を遅らせる）が生じ、その結果、脱酸剤の酸化ロスが格段に低減するものと考えられる。
【００１８】
以下、本発明における構成要件を、前記の範囲に限定した理由について説明する。
本発明では、焼成工程の昇温過程において、 ７００℃以上、（最高温度−５０℃）以下の温度域を５℃／ｍｉｎ以上の昇温速度で昇温する必要がある。
まず、昇温速度を制御すべき温度範囲の下限を ７００℃としたのは、温度が ７００℃以上になると、上述したとおり、Ｆｅ−Ｓｉ粒子の変質（酸化）が懸念されるからである。一方、フラックス粉体は熱伝達性があまり良くないので、均熱により均一材質とするには均熱温度域（最高温度〜最高温度−５０℃の温度域）において少なくとも５分程度の均熱処理が必要である。従って、かかる均熱温度域に至るまでの昇温過程における温度範囲の上限として（最高温度−５０℃）を定めた。
また、かかる温度域における昇温速度を５℃／ｍｉｎ以上に限定したのは、昇温速度が５℃／ｍｉｎ未満ではＦｅ−Ｓｉ粒子が変質（酸化）して、溶接時における脱酸効果が小さくなるからである。
【００１９】
次に、原料配合時に、脱酸剤として用いるＦｅ−Ｓｉが備えるべき条件について説明する。
Ｆｅ−ＳｉのＳｉ含有量：３０〜８０ｗｔ％
Ｓｉ含有量が８０ｗｔ％を超えると、添加するＦｅ−Ｓｉの絶対量が少量となりフラックス全体に均一に分布させるのが困難となるため、８０ｗｔ％以下とした。また、Ｓｉ含有量が３０ｗｔ％未満では、Ｆｅ−Ｓｉを多量に添加する必要が生じ、その多量添加によりフラックス中の鉄分が増大し、これが原因となって溶接ビード表面性状が劣化するので、３０ｗｔ％以上にした。
【００２０】
Ｆｅ−Ｓｉの粒度構成：１０６ μｍ を超える粒子の割合が１０ｗｔ％以下で、かつ４５μｍ 未満の粒子の割合が５０ｗｔ％以下
Ｆｅ−Ｓｉ粒子のうち、１０６ μｍ を超える粒子の割合が１０ｗｔ％を超えると繰り返し利用していくうちに脱酸効果および脱酸効率が低下して、ポックマークが出易くなるため、１０ｗｔ％以下に限定した。一方４５μｍ 未満の粒子の割合が５０ｗｔ％以上になると高温焼成時に細かいＦｅ−Ｓｉの粒子が酸化消失するため、５０ｗｔ％以下に限定した。
【００２１】
フラックス中におけるＦｅ−Ｓｉの含有量：１〜１０ｗｔ％
フラックス全体に対してＦｅ−Ｓｉの含有量が１ｗｔ％に満たないと所望の脱酸効果が得られず、一方１０ｗｔ％を超えて添加しても脱酸効果は飽和に達するので、Ｆｅ−Ｓｉ含有量は１〜１０％の範囲に限定した。
【００２２】
本発明では、サブマージアーク溶接用フラックスの製造に当たり、基本的に、 ７００℃以上、（最高温度−５０℃）以下の温度域における昇温速度を５℃／ｍｉｎ以上に規制することにより、また好ましくはさらに、フラックス中に脱酸剤として添加するＦｅ−Ｓｉ粒子について、その成分、粒度構成および添加量を上記の範囲に制限することによって、所望の効果を得ることができるが、焼成型フラックスのその他の代表組成については、次のとおりである。
【００２３】
ｔｏｔａｌ ＳｉＯ_２：３０〜７０ｗｔ％
ＳｉＯ_２は、ビード外観を良好に保つための造滓剤として添加する。しかしながら、ｔｏｔａｌ ＳｉＯ_２が３０ｗｔ％未満ではその添加効果に乏しく、特に高速隅肉溶接のようにビード端部のなじみが重要な場合には、３０ｗｔ％未満では良好なビード形状を保持できない。一方、７０ｗｔ％を超えて多量に含まれると粘性が高くなりすぎてかえってビード外観が乱れ易くなり、またスラグの剥離性が劣化するなどの不具合が生じる。従って、ｔｏｔａｌ ＳｉＯ_２量は３０〜７０ｗｔ％程度とするのが好ましい。
【００２４】
マンガン酸化物：５〜４０ｗｔ％（ＭｎＯ量換算で）
隅肉溶接用フラックスとしては、溶接速度が速くなってもビード端部のなじみが良好である必要がある。そのためには、マンガン酸化物を含有するスラグとすることが好適であるが、添加量がＭｎＯ量換算で５ｗｔ％に満たないとその効果が認められず、一方４０ｗｔ％を超えて含有されると溶融池でＣＯ反応が激しくなる結果、ビード外観が劣化するので、マンガン酸化物量は５〜４０ｗｔ％程度とすることが好ましい。
【００２５】
ＭｇＯ：３〜３０ｗｔ％
ＭｇＯは、スラグの融点および粘性を調整し、スラグ剥離性を確保するのに有用な成分である。しかしながら、含有量が３ｗｔ％未満では十分な効果が得られず、一方３０ｗｔ％を超えると粘性が低下しすぎたり、融点が上昇しすぎてビード外観が劣化する傾向が現れる。それ故、ＭｇＯは３〜３０ｗｔ％程度とするのが望ましい。
【００２６】
Ａｌ_２０_３ ：２〜 ２０ ｗｔ％
Ａｌ_２０_３ は、スラグの粘性および融点を調整する上で重要な成分であるが、２ｗｔ％未満ではその添加効果に乏しく、一方２０ｗｔ％を超えると融点が上昇しすぎてビード形状の劣化を招くので、含有量は２〜２０ｗｔ％程度とするのが望ましい。
【００２７】
また、その他に、ＣａＯやＣａＦ_２を含有させることも好ましい。
ＣａＯ：１０ｗｔ％以下
ＣａＯは、スラグの流動性に影響を及ぼす成分であり、１０ｗｔ％を超えて多量に含有されると流動性が阻害されてビード形状の劣化を招くので、ＣａＯは１０ｗｔ％以下程度とするのが好ましい。
【００２８】
ＣａＦ_２：１５ｗｔ％以下
ＣａＦ_２は、スラグの流動性を向上させる成分であるが、１５ｗｔ％を超えるとスラグが流動し易くなるので、ＣａＦ_２は１５ｗｔ％以下程度とするのが望ましい。なお、特に好ましい範囲は５ｗｔ％以下である。
【００２９】
以上、代表的なフラックス組成について説明したが、その他にも必要に応じてＴｉＯ_２：１０ｗｔ％以下、ＢａＯ：５ｗｔ％以下、ＺｒＯ_２：５ｗｔ％以下、Ｂ_２０_３：４ｗｔ％以下、 ＣａＣＯ_３：５ｗｔ％以下から選ばれる１種以上を添加しても良い。
ＴｉＯ_２は、溶接中に還元され、溶接金属中へＴｉが移行して溶接金属の靱性を向上させる作用がある。しかしながら、１０ｗｔ％を超えるとかえって靱性を劣化させる。
ＢａＯ，ＺｒＯ_２は、スラグの塩基度や融点を調整するために添加する。しかしながら、５ｗｔ％を超える添加はいずれもビード外観やスラグ剥離性を劣化させる。
Ｂ_２０_３は、溶接中の還元反応により、溶接金属中にＢが移行して溶接金属の靱性改善に寄与する。しかしながら、４ｗｔ％を超えると溶着金属の凝固割れを助長する。
ＣａＣＯ_３ は、溶接中に分解して ＣＯ_２を発生し、水素分圧を下げるため溶接金属中の水素量の低減に有効である。しかしながら、５ｗｔ％を超えるとビード外観を劣化させる。
【００３０】
上述した好適組成となるようにフラックス原料粉と、前述した成分および粒度構成に調整されたＦｅ−Ｓｉとを適正量添加、配合して、結合剤と共に混練した後、造粒し、ついで前述した焼成条件で焼成する。
造粒法はとくに限定しないが、転動式造粒機や押し出し式造粒機を用いるのが好ましい。
造粒したのち、ダストの除去や粗大粒の解砕などの整粒処理を行って、粒子径：０．０７５ 〜２．５ ｍｍの大きさの粒子にするのが好ましい。整粒処理は焼成後に行っても良い。
なお、結合剤（バインダ）としては、ポリビニルアルコールなどの水溶液や水ガラスが好適である。中でも、従来から用いられているＳｉＯ_２とＮａ_２Ｏのモル比：１〜５の珪酸ソーダ（水ガラス）が有利に適合する。また、水ガラス使用量はフラックス原料１ｋｇあたり８０〜１５０ ｃｃ程度でよい。
また、焼成温度については、焼成温度が ７５０℃を下回ると結合剤（バインダ）より持ち込まれた水分の乾燥が不十分となり、溶着金属中拡散性水素の増加を招くので、焼成温度は ７５０℃以上とする必要がある。
なお、焼成は、ロータリーキルン、定置式バッチ炉およびベルト式焼成炉などを用いて行う。
【００３１】
【実施例】
実施例１
表１に示したような比率になるように配合した原料を、水ガラスを結合剤として１２〜２００ メッシュに造粒し、１０００℃、５分の条件で焼成した。Ｆｅ−Ｓｉとしては、１０６ μｍ 超が１０ｗｔ％以下、４５μｍ 未満が５０ｗｔ％以下の粒度分布を有し、Ｓｉ含有量が１８〜７６ｗｔ％のものを用いた。なお、フラックスの焼成はロータリーキルンにより行い、 ７００〜９５０ ℃の温度域における平均昇温速度は１２℃／ｍｉｎであった。なお、昇温速度は、１０ｍｍ角の鉄片を付けた熱電対を用いて測定した。
これらのフラックスと２ｗｔ％Ｍｎ系ワイヤ（４．８ｍｍφ）を用いて、溶接電流：８５０ Ａ， 溶接電圧：４０Ｖ， 溶接速度：５０ｃｍ／ｍｉｎの溶接条件で、ＳＭ４００ 相当の鋼板に対して下向き隅肉溶接を行い、ビード外観について調査した。
得られた結果を表３に示す。
【００３２】
【表３】

【００３３】
同表から明らかなように、焼成時における昇温速度、さらにはＦｅ−Ｓｉの成分および添加量が本発明の適正範囲を満足するフラックス（Ｎｏ．２， ３）を用いた場合には良好なビード外観を得ることができた。
これに対し、Ｆｅ−Ｓｉ中のＳｉ含有量が適正範囲に満たないもの（Ｎｏ．１）は、ポックマーク発生個数が適合例に比べると非常に多く、ビード表面性状が格段に劣っていた。
【００３４】
実施例２
表４に示す組成のオリビンサンドを用いて、表５に示す比率になるように配合した原料を、水ガラスを造粒剤として混練し、１２〜２００ メッシュに造粒後、乾燥、焼成したのち、粒度調整を行い、フラックスを得た。
フラックスの焼成はベルト式焼成炉により行い、 ９００℃、５分の条件で焼成した。炉内におけるフラックス充填層厚は変化させず、炉内への投入量、ベルト速度および炉内設定温度を変化させることにより、フラックス焼成時の昇温速度を変化させた。なお、フエロシリコンとしては、粒度分布を調整したＦｅ−４７ｗｔ％Ｓｉを用いた。
これらのフラックスと２ｗｔ％Ｍｎ系ワイヤ（４．８ｍｍφ）を用いて、溶接電流：９００ Ａ， 溶接電圧：４０Ｖ， 溶接速度：６０ｃｍ／ｍｉｎの溶接条件で、ＳＳ４００ 相当の鋼板に対して下向き隅肉シングル溶接を行い、ビード外観について調査した。
得られた結果を表６に示す。
【００３５】
【表４】

【００３６】
【表５】

【００３７】
【表６】

【００３８】
表６から明らかなように、本発明の要件を満足する条件で製造したフラックスを用いた場合には、良好なビード外観を得ることができた。
【００３９】
【発明の効果】
かくして、この発明によれば、高速溶接時においても、ガスの発生を効果的に抑制して、耐ポックマーク性に優れるだけでなく、良好な溶接作業性を有するサブマージアーク溶接用の高温焼成型フラックスを安定して得ることができる。[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method for producing a fired flux for submerged arc welding suitable for welding steel structures such as ships, marine structures, storage tanks, steel frames and bridges, and particularly to a welding method used for steel beams for buildings and the like. The present invention relates to a method for producing a fired flux for submerged arc welding having excellent welding workability, in which a welded portion having no defect is stably obtained, for example, when fillet joint welding of an assembling type H-shaped member is performed by high-speed submerged arc welding. Things.
[0002]
[Prior art]
Submerged arc welding (submerged arc welding) flux is usually composed mainly of 2 silicon oxide (SiO _2), magnesium oxide thereto (MgO), manganese oxide (MnO, _Mn 3 _{0 4,} etc.), calcium oxide (CaO) , Alumina (Al ₂ O ₃ ) and other oxides, fluorides and the like.
The flux for submerged arc welding is classified into a molten flux, a fired flux (including a sintered flux, the same applies hereinafter), and a mixed flux depending on the manufacturing method.
[0003]
Of these, the calcination type flux is generally manufactured by adding water glass (sodium silicate) or the like as a binder (binder) to a flux raw material powder such as an oxide or a fluoride, followed by kneading, granulating, drying and firing. Have been. In rare cases, the binder may be omitted. Such a sintering flux has the advantage of being inexpensive because it can be manufactured with relatively simple equipment, and that the welding metal component can be adjusted because a deoxidizing agent or alloying element can be added.
[0004]
However, the sintering flux greatly changes the quality of the flux and the characteristics of the welded portion depending on the raw material.
For example, welding defects such as pits and pock marks occur at the welded portions. These welding defects are generated due to CO, CO ₂ gas generated during welding due to moisture such as water of crystallization in the raw material or a raw material oxide serving as an oxygen source.
[0005]
In order to solve the above-mentioned problem, in a low-temperature firing type flux which is fired at a low temperature (700 ° C. or less), improvement of welding defect resistance has been achieved by adding a carbonate or a deoxidizing agent to the flux.
On the other hand, a high-temperature firing flux which is fired at a high temperature (700 to 1200 ° C.) can achieve low hydrogenation of the deposited metal without using a carbonate, and thus has excellent high-speed weldability, but can be used as a deoxidizing agent. Was very poor, and the pock mark resistance was poor. In addition, at present, such studies have hardly been conducted.
[0006]
As an example of adding metal powder for the purpose of deoxidation, examples of Fe-Si and Si-Mn are described in JP-B Nos. 32-409 and 44-13249. High-temperature firing fluxes are often used as deoxidizing agents because the deoxidizing agent is often degraded (oxidized or nitrided) during high-temperature firing and the effect of the deoxidizing agent is reduced. Is the main.
However, even when Fe-Si and Si-Mn are used as the deoxidizing agent, the deoxidizing agent is deteriorated due to high-temperature sintering conditions or the like. Problems such as not being able to obtain excellent welding workability remain.
[0007]
In addition, Japanese Patent Application Laid-Open No. 62-68695 discloses a high-temperature sintering type flux in which Si in the flux is 0.5% by weight or less.
However, this technique suppresses the amount of Si in the flux to 0.5 wt% or less, thereby reducing the influence on the welding workability due to the deterioration of the deoxidizer during high-temperature firing. There is no study on a firing method or the like.
[0008]
[Problems to be solved by the invention]
The present invention has been developed in view of the above-mentioned current situation. By using Fe-Si as a deoxidizing agent and controlling the rate of temperature rise in a temperature range of 700 ° C. or more during firing treatment after granulation. It is an object of the present invention to propose an advantageous method for producing a fired flux for submerged arc welding, in which a weld portion having no defect is stably obtained and having excellent welding workability.
[0009]
[Means for Solving the Problems]
The inventors of the present invention have conducted intensive studies on a method for stably obtaining a defect-free weld when producing a firing flux for submerged arc welding that is fired at a temperature of 750 ° C. or higher. With a flux to which Si is added, it has been found that optimizing the firing conditions during production is effective for improving workability during welding and suppressing the occurrence of defects.
The present invention is based on the above findings.
[0010]
That is, the gist configuration of the present invention is as follows.
1. As a deoxidizer, Si content be 30 ~ 80 wt%, and particle diameter: 106 mu m exceeds 10% or less by weight ratio, particle size: 45 mu m less than the particle size distribution of 50% or less by weight ratio In a method for producing a flux for submerged arc welding, a firing type flux raw material in which Fe - Si particles having a content of 1 to 10 wt % are blended and fired at a temperature of 750 ° C. or higher after granulation. , 700 ° C. or higher, (maximum temperature -50 ° C.) following production method of submerged arc welding sintering type flux, wherein heating to Rukoto the temperature range at 5 ° C. / min or more heating rate.
[0011]
2. In the above item 1, the flux component is
total SiO ₂ : 30 to 70 wt%,
Manganese oxide (in terms of MnO amount): 5 to 40 wt%,
MgO: 3 to 30 wt%,
A1 ₂ 0 _3: 2~20wt%
A method for producing a fired flux for submerged arc welding having a composition containing:
[0013]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, the present invention will be described specifically.
First, the circumstances that led to the present invention will be described based on experimental results.
Raw materials adjusted to have the compounding ratios shown in Table 1 were granulated to 12 to 200 mesh using water glass as a binder, and fired at 1100 ° C. for 5 minutes.
At this time, the firing of the flux was performed using a stationary batch furnace, and the effect of the heating rate during the firing of the flux was investigated.
The heating rate was measured using a thermocouple at a temperature that was considered to be the average heating rate position in the flux-packed layer and that was 1/4 of the filling height from the surface of the central portion of the flux-filled container. The average temperature increase rate in the temperature range of 700 to 1050 ° C was determined.
[0014]
Using these fluxes and a 2 wt% Mn-based wire (4.8 mmφ), welding current: 750 A, welding voltage: 35 V, welding speed: 40 cm / min. Then, the bead appearance was examined.
The obtained results are shown in Table 2. As is clear from the table, it is understood that the rate of temperature rise during the firing of the flux greatly affects the appearance of the weld bead.
[0015]
[Table 1]

[0016]
[Table 2]

[0017]
The following can be considered as a reason why the rate of temperature rise during flux firing is closely related to the appearance of the weld bead.
Usually, Fe-Si and Si-Mn are generally known as metal powders added to a high-temperature firing type flux for the purpose of deoxidation. However, in the temperature range of 700 ° C. or higher, although the reaction rate is low, , Gradually deteriorates (oxidizes), and the effect as a deoxidizing agent decreases. In this regard, if the heating rate in the temperature range of 700 ° C. or more is set to 5 ° C./min or more, the oxidation behavior of the deoxidizing agent changes to affect the oxidation rate of the deoxidizing agent near the maximum temperature (at the time of heating. It is considered that the oxidation amount of the deoxidizing agent is small and the progress of the oxidation is slowed down.
[0018]
Hereinafter, the reason why the constituent elements in the present invention are limited to the above range will be described.
In the present invention, it is necessary to raise the temperature in a temperature range of 700 ° C. or more and (maximum temperature −50 ° C.) or less at a rate of 5 ° C./min or more in the heating process of the firing step.
First, the lower limit of the temperature range in which the rate of temperature rise should be controlled is set to 700 ° C., because when the temperature is 700 ° C. or higher, there is concern about the alteration (oxidation) of the Fe—Si particles as described above. On the other hand, since the heat transfer property of the flux powder is not so good, in order to make the material uniform by soaking, at least about 5 minutes of soaking heat treatment in the soaking temperature range (the temperature range from the highest temperature to the highest temperature −50 ° C.). is necessary. Therefore, (maximum temperature −50 ° C.) was determined as the upper limit of the temperature range in the heating process up to the soaking temperature range.
Further, the reason why the heating rate in such a temperature range is limited to 5 ° C./min or more is that when the heating rate is less than 5 ° C./min, the Fe—Si particles are altered (oxidized) and the deoxidizing effect during welding is reduced. This is because it becomes smaller.
[0019]
Next, conditions to be included in Fe—Si used as a deoxidizer at the time of compounding the raw materials will be described.
Si content of Fe-Si: 30 to 80 wt%
If the Si content exceeds 80 wt%, the absolute amount of Fe-Si to be added becomes small and it becomes difficult to uniformly distribute the entire flux, so the content was set to 80 wt% or less. On the other hand, if the Si content is less than 30 wt%, it is necessary to add a large amount of Fe-Si, and the addition of a large amount increases the iron content in the flux, which deteriorates the surface properties of the weld bead. % Or more.
[0020]
Particle size composition of Fe-Si: the proportion of particles exceeding 106 μm is 10 wt% or less and the proportion of particles less than 45 μm is 50 wt% or less Among the Fe-Si particles, the proportion of particles exceeding 106 μm exceeds 10 wt% Since the deoxidizing effect and the deoxidizing efficiency are reduced during repeated use and a pock mark easily appears, the content is limited to 10 wt% or less. On the other hand, when the proportion of particles having a particle size of less than 45 μm is 50 wt% or more, fine Fe—Si particles are oxidized and disappeared during high-temperature sintering.
[0021]
Fe-Si content in the flux: 1 to 10 wt%
If the content of Fe-Si with respect to the entire flux is less than 1 wt%, the desired deoxidizing effect cannot be obtained. On the other hand, even if the content exceeds 10 wt%, the deoxidizing effect reaches saturation. The content was limited to the range of 1 to 10%.
[0022]
In the present invention, in the production of the flux for submerged arc welding, it is basically preferable that the heating rate in the temperature range of 700 ° C. or more and (maximum temperature −50 ° C.) or less be regulated to 5 ° C./min or more. Further, with respect to Fe-Si particles added as a deoxidizing agent in the flux, the desired effect can be obtained by restricting the components, the particle size composition, and the amount added to the above ranges. Other representative compositions are as follows.
[0023]
total SiO ₂ : 30 to 70 wt%
SiO ₂ is added as a slag-making agent for maintaining good bead appearance. However, if the total SiO ₂ content is less than 30 wt%, the effect of the addition is poor. In particular, if the bead end conformity is important, such as in high-speed fillet welding, a good bead shape cannot be maintained if the total SiO ₂ content is less than 30 wt%. On the other hand, if it is contained in a large amount exceeding 70% by weight, the viscosity becomes too high, and the bead appearance is more likely to be disturbed and the slag removability is deteriorated. Therefore, the total SiO ₂ amount is preferably set to about 30 to 70 wt%.
[0024]
Manganese oxide: 5-40 wt% (in terms of MnO amount)
The fillet welding flux needs to have good bead end conformability even at high welding speeds. For this purpose, it is preferable to use a slag containing manganese oxide. However, if the added amount is less than 5 wt% in terms of MnO amount, the effect is not recognized, while if the added amount exceeds 40 wt%. Since the CO reaction becomes intense in the molten pool, the bead appearance is deteriorated. Therefore, the manganese oxide content is preferably set to about 5 to 40 wt%.
[0025]
MgO: 3 to 30 wt%
MgO is a component useful for adjusting the melting point and viscosity of the slag and ensuring the slag removability. However, if the content is less than 3 wt%, a sufficient effect cannot be obtained, while if it exceeds 30 wt%, the viscosity tends to be too low or the melting point tends to be too high, and the bead appearance tends to deteriorate. Therefore, the content of MgO is desirably about 3 to 30 wt%.
[0026]
Al ₂ O ₃ : 2 to 20 wt%
Al ₂ O ₃ is an important component for adjusting the viscosity and melting point of the slag. However, if it is less than 2 wt%, the effect of its addition is poor. On the other hand, if it exceeds 20 wt%, the melting point rises too much and the bead shape deteriorates. Therefore, the content is desirably about 2 to 20% by weight.
[0027]
In addition, it is also preferable to contain CaO or CaF ₂ .
CaO: 10 wt% or less CaO is a component that affects the fluidity of slag. If it is contained in a large amount exceeding 10 wt%, the fluidity is impaired and the bead shape is deteriorated. Therefore, CaO is 10 wt% or less. It is preferable to set the degree.
[0028]
CaF ₂ : 15 wt% or less CaF ₂ is a component that improves the fluidity of slag. However, if it exceeds 15 wt%, the slag flows easily. Therefore, it is desirable that CaF ₂ be about 15 wt% or less. Note that a particularly preferred range is 5 wt% or less.
[0029]
The typical flux composition has been described above. However, if necessary, TiO ₂ : 10 wt% or less, BaO: 5 wt% or less, ZrO ₂ : 5 wt% or less, B ₂ O ₃ : 4 wt% or less, CaCO ₃ : One or more selected from 5 wt% or less may be added.
TiO ₂ is reduced during welding and has an effect of improving the toughness of the weld metal by transferring Ti into the weld metal. However, if it exceeds 10 wt%, the toughness is rather deteriorated.
BaO and ZrO ₂ are added to adjust the basicity and melting point of the slag. However, any addition exceeding 5 wt% deteriorates bead appearance and slag removability.
B ₂ 0 ₃ is the reduction in welding, contributing to toughness improvement of the weld metal and transition B in the weld metal. However, when the content exceeds 4 wt%, solidification cracking of the deposited metal is promoted.
CaCO ₃ is decomposed during welding to generate CO ₂ and reduces the hydrogen partial pressure, which is effective in reducing the amount of hydrogen in the weld metal. However, if the content exceeds 5 wt%, the bead appearance deteriorates.
[0030]
Flux raw material powder and Fe-Si adjusted to the above-mentioned components and particle size composition are added and blended in an appropriate amount so as to have the above-described preferable composition, kneaded together with a binder, granulated, and then described above. Fire under firing conditions.
The granulation method is not particularly limited, but it is preferable to use a rolling granulator or an extrusion granulator.
After the granulation, it is preferable to perform a particle sizing treatment such as dust removal or crushing of coarse particles to obtain particles having a particle diameter of 0.075 to 2.5 mm. The sizing process may be performed after firing.
In addition, as the binder (binder), an aqueous solution such as polyvinyl alcohol or water glass is preferable. Among them, conventionally used sodium silicate (water glass) having a molar ratio of SiO ₂ to Na ₂ O of 1 to 5 is advantageously suitable. The amount of water glass used may be about 80 to 150 cc per 1 kg of the flux material.
Regarding the firing temperature, if the firing temperature is lower than 750 ° C., the moisture brought in from the binder (binder) is insufficiently dried, which causes an increase in the diffusible hydrogen in the deposited metal. It is necessary to
The firing is performed using a rotary kiln, a stationary batch furnace, a belt-type firing furnace, or the like.
[0031]
【Example】
Example 1
Raw materials blended so as to have the ratios shown in Table 1 were granulated to 12 to 200 mesh using water glass as a binder, and fired at 1000 ° C. for 5 minutes. As the Fe-Si, those having a particle size distribution of 10 wt% or less when over 106 μm, 50 wt% or less when less than 45 μm, and a Si content of 18 to 76 wt% were used. The firing of the flux was performed by a rotary kiln, and the average rate of temperature increase in a temperature range of 700 to 950 ° C. was 12 ° C./min. The heating rate was measured using a thermocouple with a 10 mm square iron piece.
Using these fluxes and a 2 wt% Mn-based wire (4.8 mmφ), a welding fillet of 850 A, a welding voltage of 40 V, a welding speed of 50 cm / min, and a downward fillet for a steel plate equivalent to SM400 were used. Welding was performed and the bead appearance was examined.
Table 3 shows the obtained results.
[0032]
[Table 3]

[0033]
As is clear from the table, when the flux (No. 2, 3) in which the rate of temperature rise during firing, and furthermore, the components and the amount of Fe—Si satisfy the appropriate range of the present invention, good results are obtained. The bead appearance was obtained.
On the other hand, when the content of Si in Fe-Si was less than the appropriate range (No. 1), the number of occurrences of pock marks was much larger than that of the conforming example, and the bead surface properties were remarkably inferior.
[0034]
Example 2
Using olivine sand having the composition shown in Table 4, the raw materials mixed in the ratio shown in Table 5 were kneaded with water glass as a granulating agent, granulated to 12 to 200 mesh, dried, and fired. The particle size was adjusted to obtain a flux.
The flux was fired in a belt-type firing furnace at 900 ° C. for 5 minutes. The thickness of the flux-filled layer in the furnace was not changed, and the heating rate during the firing of the flux was changed by changing the amount charged into the furnace, the belt speed, and the set temperature in the furnace. In addition, Fe-47 wt% Si whose grain size distribution was adjusted was used as the ferrosilicon.
Using these fluxes and a 2 wt% Mn-based wire (4.8 mmφ), welding current: 900 A, welding voltage: 40 V, welding speed: 60 cm / min. Single welding was performed and the bead appearance was investigated.
Table 6 shows the obtained results.
[0035]
[Table 4]

[0036]
[Table 5]

[0037]
[Table 6]

[0038]
As is clear from Table 6, when the flux manufactured under the conditions satisfying the requirements of the present invention was used, a good bead appearance could be obtained.
[0039]
【The invention's effect】
Thus, according to the present invention, even at the time of high-speed welding, the generation of gas is effectively suppressed, and not only the pock mark resistance is excellent, but also a high-temperature firing type for submerged arc welding having good welding workability. The flux can be obtained stably.

Claims (2)

As a deoxidizer, Si content be 30 ~ 80 wt%, and particle diameter: 106 mu m exceeds 10% or less by weight ratio, particle size: 45 mu m less than the particle size distribution of 50% or less by weight ratio In a method for producing a flux for submerged arc welding, a firing type flux raw material in which Fe - Si particles having a content of 1 to 10 wt % are blended and fired at a temperature of 750 ° C. or higher after granulation. , 700 ° C. or higher, (maximum temperature -50 ° C.) following production method of submerged arc welding sintering type flux, wherein heating to Rukoto the temperature range at 5 ° C. / min or more heating rate. In claim 1, the flux component is:
total SiO ₂ : 30 ~ 70wt%,
Manganese oxide (in terms of MnO amount): 5-40 wt%,
MgO: 3 to 30 wt%,
A1 ₂ 0 _3: 2~20wt%
A method for producing a fired flux for submerged arc welding having a composition containing: