JPS5945467B2 - Single electrode oscillating submerged mark welding method - Google Patents

Description

【発明の詳細な説明】 この発明は、単電極揺動サブマージアーク溶接法に関し
、とくに、単電極サブマージアーク溶接を大入熱量で高
能率に適用する場合に不可避な溶接熱影響部の結晶粗大
化と、該熱影響部領域の肥厚化とをあわせ解決しようと
するものである。DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a single electrode oscillating submerged arc welding method, and in particular, to prevent coarsening of crystals in the weld heat affected zone that is inevitable when applying single electrode submerged arc welding with a large heat input and high efficiency. This is an attempt to solve the problem of thickening of the heat-affected zone region.

この発明の適用は軟鋼、高張力鋼、耐熱鋼および低温用
鋼などの如何を問わず、何れも大入熱量で溶接した際に
生じる溶接熱影響部の結晶粒粗大化を抑制するとともに
、熱影響を受ける領域を著しく狭小化し、かくして高じ
ん性の溶接熱影響部を得る高能率な単電極揺動サブマー
ジアーク溶接方法を提供しようとするものである。近年
、溶接工数を削減し、溶接コストを低下させるために高
能率な大入熱自動浴接とくにサブマージアーク溶接方法
が広く採用されつつある。This invention can be applied to mild steel, high-strength steel, heat-resistant steel, and low-temperature steel, to suppress grain coarsening in the weld heat affected zone that occurs when welding with a large heat input, and to The present invention aims to provide a highly efficient single-electrode oscillating submerged arc welding method that significantly narrows the affected area and thus obtains a highly tough weld heat-affected zone. In recent years, highly efficient high heat input automatic bath welding, particularly submerged arc welding, has been widely adopted in order to reduce welding man-hours and welding costs.

しかし、従来のこの種溶接方法では溶接入熱量の増大に
ともなつて溶接熱影響部、とくにボンド近傍は結晶粒和
犬化組織を呈し、さらにその領域が拡大するために、じ
ん性が著しく劣化してぜい性破壊を生じる危険性が大と
なり、重大な問題点となる。そこでこ減まではじん性劣
化を防止するために、溶接能率、溶接コストを儀性にし
て各種鋼材に適応した制限人熱量内で施工されていた。However, in conventional welding methods of this type, as the welding heat input increases, the weld heat affected zone, especially near the bond, exhibits a grain-hardened structure, and as the area expands, the toughness deteriorates significantly. This increases the risk of brittle destruction, which poses a serious problem. Up until this point, in order to prevent deterioration of toughness, welding efficiency and welding costs had been taken into account and work was carried out within limits on the amount of human heat that was applied to each type of steel.

最近になりこれら問題点の解決策として鋼材の成分組成
、あるいは溶接方法についていくつか提案されている。Recently, several proposals have been made regarding the composition of steel materials or welding methods as solutions to these problems.

たとえば鋼材の成分組成で改善するために溶接熱影響部
のオーステナイト粒柑大化を防止し、かっ微細フェライ
トの析出の核となりうるような特殊元素を微量添加する
とともに、鋼中の炭素、窒素含有量を低下させることで
ある。For example, in order to improve the composition of steel materials, we prevent the austenite grain size in the weld heat-affected zone, add small amounts of special elements that can become the nucleus for the precipitation of fine ferrite, and improve the carbon and nitrogen content in the steel. The goal is to reduce the amount.

この方法によると溶接入熱量５Ｏ、００ＯＪ０Ｕｌｅ／
／ＣＴＩＬ以上でも熱影響部は微細化組織を呈し、高じ
ん性が得られることが示されているがしかし、鋼材中の
微量元素の分布および形態をル１］御するために高度の
製造技術を必要とすること、さらに鋼材価格が上昇する
などの欠点を残す。いつぼう、溶接方法についてもたと
えば、電極が通過したのち溶接部の裏面側から低温液体
あるいは気体を溶接部に噴射して強制冷却し、微細組織
にしてじん性改善を行う方法がある。According to this method, the welding heat input is 5O, 00OJ0Ule/
It has been shown that the heat-affected zone exhibits a refined structure and high toughness can be obtained even above CTIL. However, advanced manufacturing technology is required to control the distribution and morphology of trace elements in the steel material. However, there are still drawbacks such as the need for steel materials and the rise in steel prices. Regarding welding methods, for example, after the electrode has passed, there is a method in which low-temperature liquid or gas is injected into the welded part from the back side of the welded part to forcefully cool it and create a fine structure to improve the toughness.

しかし、この方法では母板板厚が比較的小さく、両側一
層で溶接する場合にはかなり効果的であるが、板厚が大
きくなり、多層盛の溶接を要するような場合には冷却効
果が低下して十分なじん性が得られないし、さらに、冷
却用液体あるいは気体を噴射する装置が必要となり、か
つ溶液速度と同期しなければならないので、装置が複雑
、大型になり、その操作上の制約から挟小部の溶接個所
には適用しがたい。そこで発明者らは多くの実験、検討
を行つた結果溶融池形状制御の有効性を明らかにする新
たな知見を得、これにもとづき、単電極サブマージアー
ク溶接法において電極を適切に揺動させると、溶接熱影
響部の品質劣化防止に対し、顕著な効果をもたらし得る
ことを見い出し、上述した従来技術の問題点を有利に克
服したものである。However, this method is quite effective when the base plate thickness is relatively small and welding in a single layer on both sides, but the cooling effect decreases when the plate thickness becomes large and multi-layer welding is required. In addition, a device for injecting cooling liquid or gas is required and must be synchronized with the solution velocity, making the device complex and large, and its operational constraints It is difficult to apply this method to welded parts with narrow parts. As a result of many experiments and studies, the inventors obtained new knowledge that clarified the effectiveness of molten pool shape control.Based on this, the inventors found that it is possible to appropriately swing the electrode in single-electrode submerged arc welding. The present invention has been found to have a remarkable effect on preventing quality deterioration of the weld heat affected zone, and has advantageously overcome the problems of the prior art described above.

ところで電極を揺動して溶接する方法自体は、サブマー
ジアーク溶接法やガスシールドアーク溶接法に適用され
てはいるにしても、溶接熱影響部の高じん性および浴接
能率をもとに満足させることの要請についての解決のた
めに試みられた例はない。By the way, although the method of welding by swinging the electrode is applied to submerged arc welding and gas shielded arc welding, it is not satisfactory based on the high toughness of the weld heat affected zone and the bath welding efficiency. There have been no attempts to resolve the requirement to do so.

すなわち特開昭５０−４５７５４号公報には、二つの電
極を揺動せしめて行う比較的低電流の二電極サブマージ
アーク片面溶接方法に関して、細径電極の揺動下に二電
極で個別に溶融池を生じさせ、２プール型式で接合する
方法が提案され、ここに開先幅変動に対しても確実な裏
波の形成が可能となり、良好なビード形成と先行の溶接
金属に後行電極による焼ならし効果を与えることができ
、高じん性の溶接金属が得られる旨開示されている。That is, Japanese Patent Application Laid-Open No. 50-45754 describes a comparatively low current two-electrode submerged arc single-sided welding method performed by swinging two electrodes, in which the two electrodes individually weld the molten pool while the small-diameter electrode swings. A two-pool type welding method has been proposed, which enables reliable formation of under-waves even with variations in groove width, good bead formation, and burn-out of the preceding weld metal by the trailing electrode. It is disclosed that a leveling effect can be imparted and a highly tough weld metal can be obtained.

しかしこの方法は、溶接熱影響部も後行電極の焼ならし
効果により一部改善されるが、その他の部分は焼ならし
を受けない状態で残存し、高じん性は望めない上とくに
比較的極間距離が短かいために、先行電極の溶接熱によ
り、後行電極位置では約５００〜１０００℃程度に加熱
された状態にあり、後行電極による溶接部の冷却速度は
著しく遅くなつて結晶粒粗大化を生じ、さらに最終層の
後行電極による溶接部は次層による焼ならし作用がない
ために、この部分のじん性は極めて悪くなる。すなわち
、この方法での強じん性化法は次層溶接による焼ならし
効果を利用したもので、焼ならしを受けない溶接部につ
いての強じん化は何んら配慮されていない。なおガスシ
ールドアーク溶接法でも、電極揺動はすでに適用されて
いるが、この方法は一般に電極の線径が比較的小さく、
かつ溶接電流も小さいために、第１図に揺動軌跡Ａ，ｂ
，ｃ，ｄ，ｅ，ｆ，・・・・・・をあわせ示すごとく、
溶融池Ｍは溶接ビードＢの幅全体にわたつては形成され
ず、電極Ｐの現在位置たとえばｅ点の反対方向の部分ｄ
点近傍はすでに凝固しているので、電極Ｐが揺動軌跡に
沿つてｅ点からｆ点に移動すると、比較的低温度になつ
た凝固部ｄ点近傍は再び溶融される一方、ｅ点は電極Ｐ
によるアーク加熱がなくなるために凝固が進行する。However, with this method, although the welding heat affected zone is partially improved due to the normalizing effect of the trailing electrode, other parts remain unnormalized, and high toughness cannot be expected, especially when compared. Due to the short distance between the welding electrodes, the trailing electrode is heated to approximately 500 to 1000°C due to the welding heat of the leading electrode, and the cooling rate of the weld by the trailing electrode is extremely slow. This causes coarsening of the crystal grains, and furthermore, since there is no normalizing effect of the next layer on the welded part by the trailing electrode of the final layer, the toughness of this part becomes extremely poor. In other words, this toughening method utilizes the normalizing effect of next-layer welding, and no consideration is given to strengthening the welded parts that are not subjected to normalizing. Electrode oscillation has already been applied to gas-shielded arc welding, but this method generally requires a relatively small electrode wire diameter.
In addition, since the welding current is small, the oscillation loci A and b are shown in Fig. 1.
, c, d, e, f,...
The molten pool M is not formed over the entire width of the weld bead B, but is formed at a portion d in the opposite direction of the current position of the electrode P, for example, point e.
The area near point d has already solidified, so when the electrode P moves from point e to point f along the swing trajectory, the area near point d in the solidified area, which has become relatively low, will melt again, while the point e will melt again. Electrode P
Solidification progresses because the arc heating due to is eliminated.

このような現象が繰返されるために、たとえば電極揺動
軌跡のａ点近くの溶接熱影響部１（７）冷却曲線は第２
図のごとく凹凸を生じる。すなわち、溶接熱影響部１は
電極Ｐがａ点に接近した際に、最高温度を記録し、ｂ点
に移行するとアークによる加熱がなくなり、母板への放
熱により冷却する。Because such a phenomenon is repeated, for example, the cooling curve of the welding heat affected zone 1 (7) near point a of the electrode swing trajectory becomes second.
As shown in the figure, unevenness occurs. That is, the welding heat affected zone 1 records the highest temperature when the electrode P approaches point a, and when it moves to point b, heating by the arc ceases and the welding heat affected zone 1 is cooled by heat radiation to the base plate.

さらにｃ点に近づくと溶接熱影響部１は再び加熱されて
焼ならし効果を生じ、ｄ点に移動すると再び冷却過程に
入る。このような現象が繰返される結果、熱影響部１は
焼ならしを受けて微細組織となり、じん性は改善される
わけであるがしかし、じん性改善法が焼ならし作用に専
ら依存するために、焼ならし条件たとえば温度、時間お
よび冷却速度が溶接条件によつて変化し、このため溶接
条件の設定をあやまると焼ならし条件が変動し、必ずし
も微細組織にはならず、高じん性の熱影響部が得られな
い場合もある。さらに鋼種によつては再加熱により炭化
物、窒化物の析出を生じ、低じん性になる場合もあるの
で、焼ならしを付加することが必ずしも最上の方法とは
いえない。When the welding heat affected zone 1 further approaches point c, it is heated again to produce a normalizing effect, and when it moves to point d, it starts the cooling process again. As a result of this phenomenon being repeated, the heat-affected zone 1 undergoes normalization and becomes a fine structure, and the toughness is improved. However, since the toughness improvement method depends exclusively on the normalization effect, In addition, the normalizing conditions, such as temperature, time, and cooling rate, change depending on the welding conditions. Therefore, if the settings of the welding conditions are incorrect, the normalizing conditions will change, and the fine structure will not necessarily be formed, resulting in high toughness. In some cases, the heat-affected zone cannot be obtained. Furthermore, depending on the type of steel, reheating may cause precipitation of carbides and nitrides, resulting in low toughness, so adding normalization is not necessarily the best method.

また、この方法に採用されている溶接電流は一般に１０
０〜４００Ａｍｐと小さく、溶接能率は低い。なおかよ
うな点を改善するために高電流を採用した場合は、溶融
池Ｍが大きくなつて焼ならし条件が変動するばかりか、
ガスシールド性が不良となり、溶融金属が大気中の酸素
、窒素と反応し、溶接金属のじん性劣化および気孔を生
じやすくなる。Additionally, the welding current used in this method is generally 10
The welding efficiency is low at 0 to 400 Amps. In addition, if a high current is adopted to improve the above points, the molten pool M will not only become larger and the normalizing conditions will fluctuate, but also
Gas shielding properties become poor, and the molten metal reacts with oxygen and nitrogen in the atmosphere, making it easy for the weld metal to deteriorate in toughness and form pores.

さらにアークカが強くなり、かつ電極揺動により溶融池
内の溶鋼流をみだして溶接ビード形状が悪化し、アンダ
ーカツトを生じやすくするとともに、スパツタ一が多発
生し、作業性も悪化する。また浴融スラグは電極中の脱
酸性元素が酸化物となつて先成されるために、このスラ
グ量は非常に少なく、ビード形状を整えるだけの量およ
び物性を調整することも困難となる。このように高電流
にした場合には多くの問題点があり、実用性がないため
低電流で溶接せざるを得ないのである。なお上記、溶接
方法にサブマージアークの適用を仮想すると、電極揺動
によつて溶接金属の溶融および凝固を繰返すような、少
ない熱量では、多量のスラグが存在し、かつ溶接スラグ
の温度がこれに追随して変化するため、アークの安定性
がそこなわれて、スラグ巻込みや、融合不良を生じやす
く、欠陥の多い溶接部になるおそれがある。要するに従
米のガスシールドアーク浴接法では電極揺動を付加して
も一般的にスラグ量が少ないために、溶接金属の溶融、
凝固の繰返しが可能なので、焼ならし効果による微細化
組織を不安定ながらも遅成し得るが、サブマージアーク
溶接法では多量の溶接スラグが生成し、これが溶接金属
の溶融、凝固の繰返しを阻害して浴接欠陥を生じる原因
となつて健全な溶接部は得られ難く、従つて電極揺動の
付加は単電極サブマージアーク溶接に適用されなかつた
のである。次に一般に溶接部の継手性能を確保するため
に、溶接後熱処理を必要とする場合が多いが、とくに８
０ｋ９／！Ｌｍ２高張力鋼や耐熱鋼は、この熱処理過程
中に熱影響部の粗粒域に粒界われが発生することが多々
ある。Further, the arc force becomes stronger, and the molten steel flow in the molten pool is pushed out due to the electrode rocking, which deteriorates the shape of the weld bead, making undercuts more likely to occur, as well as causing many spatters and worsening workability. In addition, since the bath melt slag is first formed by deoxidizing elements in the electrodes becoming oxides, the amount of this slag is very small, and it is difficult to adjust the amount and physical properties enough to shape the bead. When using such a high current, there are many problems and it is not practical, so welding must be performed at a low current. Assuming that submerged arc is applied to the welding method mentioned above, if the weld metal is repeatedly melted and solidified by electrode swinging, and the amount of heat is small, a large amount of slag will be present, and the temperature of the welding slag will be lower than this. Since the arc changes accordingly, the stability of the arc is impaired, and slag entrainment and fusion failure are likely to occur, resulting in a welded part with many defects. In short, in Jubei's gas-shielded arc bath welding method, the amount of slag is generally small even when electrode oscillation is applied, so the melting of the weld metal
Since solidification can be repeated repeatedly, the finer structure due to the normalizing effect can be unstable but delayed, but submerged arc welding generates a large amount of welding slag, which inhibits the repeated melting and solidification of the weld metal. This causes bath welding defects and makes it difficult to obtain a sound weld. Therefore, the addition of electrode oscillation has not been applied to single-electrode submerged arc welding. Next, in general, post-weld heat treatment is often required to ensure the joint performance of the welded part, but in particular
0k9/! In Lm2 high tensile strength steel and heat resistant steel, grain boundary cracking often occurs in the coarse grain region of the heat affected zone during this heat treatment process.

この原因は浴接後熱処理による内部応力の緩和過程で、
微細析出物により、結晶粒内と粒界の相対的強度差を生
じることに起因すると考えられている。われ防止策とし
ては和粒化を抑制する方法が有効で、従来はテンパビー
ドによる細粒化あるいは溶接人熱量の低減が行れている
。しかし、これら方法はいずれも溶接能率の低下、溶接
コストの上昇をまねき、効果的な方法ではなく、従つて
いまだ大入熱量で溶接を行い得る力法は提案されるに至
つていないのである。さてこの発明は上記したような従
来法の欠点および問題点を解決するために、開発研究を
重ねた結果創案されたもので、その目的とするところは
軟鋼、高張力鋼、耐熱餉および低温用鋼などを大入熱量
で溶接した際に生じる溶接熱影響部の結晶粒和大化を抑
制するとともに、熱影響を受けた領域をも狭小化するこ
とによつて、高じん性でかつ溶接後熱処理によるわれ感
受性を改善した溶接熱影響部をうる高能率な単電極サブ
マージアーク揺動溶接方法を提供するものである。The cause of this is the internal stress relaxation process due to post-bath welding heat treatment.
It is thought that this is caused by a relative strength difference between the inside of the grain and the grain boundary due to fine precipitates. An effective way to prevent cracking is to suppress grain size. Conventionally, tempering beads have been used to refine the grains or reduce the amount of heat required by the welder. However, all of these methods lead to a decrease in welding efficiency and an increase in welding costs, and are not effective methods.Therefore, a force method that can perform welding with a large amount of heat input has not yet been proposed. be. This invention was created as a result of repeated research and development in order to solve the drawbacks and problems of the conventional methods as described above, and its purpose is to apply mild steel, high tensile steel, heat-resistant steel, and low-temperature steel. By suppressing the enlargement of crystal grains in the weld heat-affected zone that occurs when welding steel etc. with a large heat input, and by narrowing the heat-affected area, we have achieved high toughness and welding properties. The present invention provides a highly efficient single-electrode submerged arc oscillation welding method that produces a weld heat-affected zone with improved sensitivity to cracking due to heat treatment.

すなわちこの発明はとくに単電極サブマージアーク溶接
方法において、溶接進行方向と交叉するように電極を揺
動させるに当り、ビード幅となるビード両端への母板溶
融エネルギーの付与が交互間欠的となり、かつビード幅
を決定するビード両端位置が揺動したアークの到達では
じめて溶融するように電極を揺動させ、溶接進行方向に
対し後半部の溶融池形状が溶接線に対して一山対称型と
なるように条件を制御した熱源を用いることにより、揺
動周期にともなう再加熱効果による熱影響部組織変化を
生じさせず、かつ高じん性微細組織の溶接熱影響部が得
られることの新しい知見に基くものである。That is, the present invention is particularly advantageous in that, in a single electrode submerged arc welding method, when the electrode is oscillated so as to intersect with the direction of welding progress, the base plate melting energy is applied intermittently to both ends of the bead, which corresponds to the bead width, and The electrode is oscillated so that it melts only when the oscillating arc reaches both ends of the bead, which determines the bead width, and the molten pool shape in the latter half of the welding direction becomes symmetrical with respect to the weld line. This new finding shows that by using a heat source with controlled conditions, it is possible to obtain a weld heat-affected zone with a highly tough microstructure without causing any changes in the heat-affected zone structure due to the reheating effect associated with the oscillation period. It is based on

従つて大人熱溶接方法にもかかわらず、溶接熱影響部に
おけるオーステナイト粒成長温度域での冷却速度が著し
く速くなつて、オーステナイト粒の粗大化が防止され、
微細化組織を呈するとともに、熱影響部幅も狭くなつて
高じん性およびＳＲわれ感受性の改善が達成でき、しか
も高電流で溶接するために高能率で溶接工数および浴接
コストが削減できるのである。Therefore, despite the adult heat welding method, the cooling rate in the austenite grain growth temperature range in the weld heat affected zone is significantly faster, preventing austenite grains from becoming coarser.
In addition to exhibiting a finer structure, the width of the heat-affected zone is narrower, achieving high toughness and improved susceptibility to SR cracking.Furthermore, since it is welded with a high current, it is highly efficient, reducing welding man-hours and bath welding costs. .

この発明の構成を具体的な実施態様について図面により
詳細に説明する。DESCRIPTION OF THE PREFERRED EMBODIMENTS The structure of the present invention will be explained in detail with reference to the drawings regarding specific embodiments.

第３図はこの発明をつき合わせ溶接に適用した溶接要領
説明図であり、電極ワイヤ３を送給ロール４によつて溶
接トーチ５を通じ、母材１，１″の開先部２に送り込む
。開先部２にはあらかじめ焼結型あるいは溶融型の溶接
用フラツクス６を散布しておき、交流あるいは直流の浴
接用電源１１により母板１，１″と電極ワイヤ３との間
に潜弧アーク９を発生させる。とくに潜弧アーク９を溶
接進行方向と交叉するように揺動させるために、溶接ト
ーチ５に揺動用電動機７の回転運動を第４図に示したよ
うな揺動軌跡１０に変換する治具８を装備する。このよ
うにして潜弧アーク９を揺動しつつ母材１，１″を単電
極でサブマージアーク溶接するのである。FIG. 3 is an explanatory diagram of a welding procedure in which the present invention is applied to butt welding, in which an electrode wire 3 is fed by a feed roll 4 through a welding torch 5 into a groove 2 of a base material 1, 1''. A sintered or molten welding flux 6 is sprinkled on the groove 2 in advance, and a latent arc is created between the mother plate 1, 1'' and the electrode wire 3 using an AC or DC bath contact power source 11. Generate arc 9. In particular, in order to swing the submerged arc 9 so as to intersect with the direction of welding progress, a jig 8 is installed on the welding torch 5 to convert the rotational motion of the swing motor 7 into a swing trajectory 10 as shown in FIG. be equipped with. In this way, the submerged arc welding of the base materials 1, 1'' is carried out using a single electrode while the submerged arc 9 is oscillated.

この場合の揺動軌跡１０は第４図に例示するごとく、溶
接進行方向と交叉するように潜弧アーク９を揺動させる
ものであれば、すべてこの発明の方法に適用できる。In this case, the swing locus 10 can be applied to the method of the present invention as long as it swings the submerged arc 9 so as to cross the direction of welding progress, as illustrated in FIG.

ところで電極数を複数にした多電極サブマージアーク溶
接法では、第２極目以降で接合される溶接部はその電極
よりも先行した電極による溶接熱の残存で、高温度に加
熱されているとともに、これら電極間距離が著しく短か
い場合には先行電極による溶融金属上にアークが発生す
るために、溶融金属が過剰に加熱される結果、溶融熱影
響部の冷却速度が著しく遅くなつて結晶粒の粗大化を生
じ、一方電極間距離が極度に長い場合には凝固したスラ
グが存在するため後行電極に安定したアークを維持でき
ず、溶接が困難となり従つてオーステナイト粒成長温度
域での冷却速度を大にするには、余剰加熱を排除した単
電極サブマージアーク溶接を不可欠とする。By the way, in the multi-electrode submerged arc welding method, which uses a plurality of electrodes, the welded parts joined after the second electrode are heated to a high temperature due to the residual welding heat from the electrode that preceded the electrode. If the distance between the electrodes is extremely short, an arc is generated on the molten metal by the leading electrode, which causes the molten metal to be excessively heated. As a result, the cooling rate of the molten heat-affected zone becomes extremely slow and the crystal grains become coarse. On the other hand, if the distance between the electrodes is extremely long, a stable arc cannot be maintained at the trailing electrode due to the presence of solidified slag, making welding difficult and reducing the cooling rate in the austenite grain growth temperature range. To achieve this, single-electrode submerged arc welding, which eliminates excess heating, is essential.

さて同一溶接入熱量として、平板上を種々の条件で電極
３を揺動する単電極サブマージアーク溶接における潜弧
アーク９の発生状態と、溶接中に母板の一端を急速に落
下させ、浴融池内の溶鋼を瞬間的に排出することにより
示した溶接進行中不断の溶融池１２の形状とを第５図に
そして溶接ビード１３の横断面形状を第６図に、また溶
接熱影響部１４のボンド近傍の冷却曲線を第７図にあら
れした。Now, assuming the same welding heat input, the generation state of the latent arc 9 in single-electrode submerged arc welding in which the electrode 3 is oscillated on a flat plate under various conditions, and the generation state of the latent arc 9 in single-electrode submerged arc welding in which the electrode 3 is oscillated on a flat plate under various conditions. FIG. 5 shows the shape of the molten pool 12, which is shown by instantaneously discharging the molten steel in the pool, and shows the cross-sectional shape of the weld bead 13 in FIG. Figure 7 shows the cooling curve near the bond.

第５図ａは電極３の揺動軌跡１０の振り幅１０ａが狭い
場合の一例であり、潜弧アーク９は溶接線１５の両側に
て溶接ビード１３の幅には達しない点１６−１６′間に
またがるほぼ長円状領域に生じ、それに起因する溶融池
１２は該領域に後続する部分にて次第に、溶接ビード１
３と同等の横幅に至るが、ここにいわゆる２次溶融を起
こして潜弧アーク９による溶込みが、溶融池１２の両側
で浅くなる。FIG. 5a shows an example where the swing width 10a of the swing locus 10 of the electrode 3 is narrow, and the latent arc 9 does not reach the width of the weld bead 13 on both sides of the weld line 15 at points 16-16'. The molten pool 12 formed in a substantially elliptical region extending between the weld beads 1
However, so-called secondary melting occurs and the penetration by the latent arc 9 becomes shallow on both sides of the molten pool 12.

この２次溶融は潜弧アーク９による加熱が溶融池１２内
で常時に加わることによつて溶融金属が過熱されること
、その結果、溶融池内に強い対流を生じることによる。
この２次溶融、すなわち長円状の潜弧アーク９の発生領
域に後続した溶融池の浅い幅広がりは、溶接ビード１３
の凝固開始位置を電極３に対し極めて後方側に伸張させ
、このとき溶融池１２に対して固液界面に沿う溶接熱影
響部１４は、高温度にさらされている時間が長くなり、
その冷却速度は、第７図ａに示すように比較的緩徐とな
り、かくして第６図ａのように溶接熱影響部１４は、肥
大化した厚みｈの領域にわたり和大化した組織を呈し、
ここに溶接熱影響部１４のじん性の劣化を米すわけであ
る。This secondary melting is caused by the fact that the molten metal is overheated by constant heating by the latent arc 9 in the molten pool 12, and as a result, strong convection is generated in the molten pool.
This secondary melting, that is, the shallow widening of the molten pool following the generation area of the oblong latent arc 9 is caused by the weld bead 13
The solidification start position of the weld is extended extremely rearward with respect to the electrode 3, and at this time, the welding heat affected zone 14 along the solid-liquid interface with respect to the molten pool 12 is exposed to high temperature for a long time,
The cooling rate becomes relatively slow as shown in FIG. 7a, and thus, as shown in FIG. 6a, the weld heat affected zone 14 exhibits an enlarged structure over an enlarged region of thickness h,
This is where the toughness of the weld heat affected zone 14 deteriorates.

この場合における溶融池１２内の、溶融物を急激排除し
たときのクレータ外観は、第５図ａのようになつている
。In this case, the appearance of the crater in the molten pool 12 when the molten material is rapidly removed is as shown in FIG. 5a.

第５図ｂでは、潜弧アーク９の発生領域が、つくろうと
する溶接ビード１３の幅に合致する間隔の位置１６−１
６２に至つてそれぞれ独立するように拡大した電極３の
揺動にて、いわばその揺動工程端で交互間けつ的なアー
ク熱源の付与にて、溶接ビード幅に合致した横幅に相当
する溶融池の前縁を、電極揺動の向きに沿い斜めに更新
する母材１のアーク熱源による溶融を生じる。In FIG. 5b, the generation area of the latent arc 9 is located at a position 16-1 at an interval that matches the width of the weld bead 13 to be created.
62, the electrodes 3 are oscillated to become independent, and by applying an arc heat source intermittently at the end of the oscillation process, a molten pool with a width corresponding to the weld bead width is formed. The front edge of the base material 1 is melted by the arc heat source, which renews the front edge obliquely along the direction of electrode swing.

すなわち位置１６又は１６ｔｉ１ｃ遅した潜弧アーク９
は、それからかけ離れている位置１６５又は１６には届
かないので、アーク熱源が揺動工程にわたり分散され、
その結果溶接池１２の前縁側にて第６図ｂに示すように
急深の溶け込みとなる。That is, the submerged arc 9 delayed by position 16 or 16ti1c
does not reach positions 165 or 16 that are far from it, so that the arc heat source is distributed over the oscillation process,
As a result, a sudden deep penetration occurs at the leading edge side of the weld pool 12 as shown in FIG. 6b.

アーク熱源の分散付与にて溶融池１２内の溶融金属の過
熱度は、それに起因する対流とともに著しく低下し、そ
の結果として２次溶融は第５図ａの場合に比し、極めて
少なく、殆ど皆無になる。それというのは、電極３の揺
動軌跡１０の振り幅の上記拡大により、潜弧アーク９の
熱源付与が母材１の溶融に主として費やされて、溶融池
１２に対する加熱効果が減じることによる。つまり、２
次溶融池１２におけるあたかも遠浅状を呈する棚底の肥
厚化を生じないので、この部分を含めた溶接熱影響部１
４への余剰の加熱が防止されることとなる。Due to the dispersion of the arc heat source, the degree of superheating of the molten metal in the molten pool 12 is significantly reduced along with the resulting convection, and as a result, secondary melting is extremely small and almost non-existent compared to the case shown in Figure 5a. become. This is because, due to the above-mentioned increase in the amplitude of the swing trajectory 10 of the electrode 3, the heat source provided by the latent arc 9 is mainly used to melt the base material 1, and the heating effect on the molten pool 12 is reduced. . In other words, 2
The welding heat affected zone 1 including this part does not cause thickening of the bottom of the shelf in the next molten pool 12, which appears to be shallow.
4 will be prevented from being excessively heated.

また溶接池１２での受熱が軽減されて、溶接ビード１３
の凝固開始位置は潜弧アーク９の発生領域側に接近し、
その結果溶融池１２内に湛えられる溶鋼量も少なくなる
ので、第６図ｂに示した溶接熱影響部１４の厚みｈは２
〜３ｍｍ以下の薄層となり該部が高温にさらされている
時間が著しく短くなる。この結果、オーステナイト粒成
長温度域での冷却速度が著しく速くなるとともに、溶接
金属凝固層の再溶融量が極めて少ないために溶接熱影響
部１４に与えられる再加熱度も小さく、冷却曲線には組
織変化を伴わないオーステナイト温度域でせいぜい数１
０℃以下の昇温しか認められず、焼ならしを受けること
もない。In addition, heat reception in the weld pool 12 is reduced, and the weld bead 13
The solidification start position approaches the generation area of the latent arc 9,
As a result, the amount of molten steel stored in the molten pool 12 is reduced, so the thickness h of the weld heat affected zone 14 shown in FIG. 6b is 2.
It becomes a thin layer of ~3 mm or less, and the time that the part is exposed to high temperature is significantly shortened. As a result, the cooling rate in the austenite grain growth temperature range becomes significantly faster, and since the amount of remelting of the weld metal solidified layer is extremely small, the degree of reheating applied to the weld heat affected zone 14 is also small, and the cooling curve has no structure. At most a few 1 in the austenite temperature range with no change
It is only allowed to rise in temperature below 0°C, and is not subjected to normalizing.

このために溶接線方向１５の熱影響部全域にわたつて均
一な微細化組織を呈し、高じん性化が達成できる。この
場合の溶融池１２の形状は溶接ビード幅全体にわたつて
、溶接進行方向に対し後半部が溶接線１５に関し対称な
先拡りＶ形をなす。このような溶融池１２の形状を且脚
することによつて溶接金属１３の再溶融は殆んど生ぜず
、溶接スラグも高温度の溶融状態にあるために、アーク
９は安定し、溶融金属および溶融スラグの対流が円渭に
行われる結果、スラグ巻込み、融合不良、アンダーカツ
トなどの溶接欠陥が皆無な溶接部１３が得られる。この
場合溶接進行中不断の溶融池形状の外観は第５図ｂのよ
うになる。これに反して第５図ｃは溶接熱影響部１４の
余剰加熱度をｂの場合よりもさらに減少した場合の一例
で、溶接部に十分な熱量が与えられないために、溶融金
属の凝固が著しく進行し、溶融池の後半部形状は二つの
溶融池が左右に重なつたいびつのＷ形をなしこの両溶融
池１２，１２″の連結部となる溶接ビード幅中心線近傍
にはスラグ巻込み、融合不良を、またビード両端部１６
，１６″にはアンダーカツトを生じ健全な溶接部１３は
得られない。Therefore, a uniform fine structure is exhibited over the entire heat affected zone in the weld line direction 15, and high toughness can be achieved. In this case, the shape of the molten pool 12 is a V-shape that extends over the entire weld bead width and whose rear half is symmetrical with respect to the weld line 15 with respect to the welding progress direction. By having such a shape of the molten pool 12, remelting of the weld metal 13 hardly occurs, and since the welding slag is also in a high temperature molten state, the arc 9 is stable and the molten metal As a result of circular convection of the molten slag, a welded portion 13 is obtained that is free from welding defects such as slag entrainment, poor fusion, and undercuts. In this case, the appearance of the molten pool that continues during welding is as shown in FIG. 5b. On the other hand, Fig. 5c is an example in which the degree of excess heating of the weld heat affected zone 14 is further reduced than in case b, and since sufficient heat is not given to the welding area, solidification of the molten metal is prevented. The molten pool progresses significantly, and the shape of the latter half of the molten pool is a distorted W-shape in which two molten pools are overlapped on the left and right, and there is slag winding near the center line of the weld bead width, which is the connecting part of both molten pools 12, 12''. In order to prevent fusion and fusion defects, the bead ends 16
, 16'', an undercut occurs and a sound welded portion 13 cannot be obtained.

さらに第５図ｄのように揺動幅を広くして、かつ低電流
で電極３の平均移動速度を小にした場合には第１図につ
きのべたように、溶融池１２は溶接ビード幅全体にわた
つて形成されずに、溶接線１５に対し偏つた形になる。Furthermore, when the oscillation width is widened and the average moving speed of the electrode 3 is made small with a low current as shown in FIG. The welding line 15 is not formed over the entire area, but is deviated from the welding line 15.

潜弧アーク９の反対側のビード端部１６５は冷却が進行
し、かなりの厚みの溶接金属凝固層が生じ潜弧アーク９
が揺動軌跡１０に沿つてビード端部１６″に接近すると
比較的低温度になつた凝固部は再び溶融され、他端部１
６はアーク加熱がなくなるために凝固が進行する。The bead end 165 on the opposite side of the submerged arc 9 continues to cool, forming a considerably thick weld metal solidified layer, and the submerged arc 9
When it approaches the bead end 16'' along the rocking trajectory 10, the solidified portion, which has reached a relatively low temperature, is melted again, and the other end 16''
In No. 6, solidification progresses due to no arc heating.

この現象が繰返されるために、溶接熱影響部１４の冷却
曲線は加熱、冷却を複数回繰返し、凹凸のある曲線とな
る。Because this phenomenon is repeated, the cooling curve of the weld heat affected zone 14 repeats heating and cooling multiple times, resulting in an uneven curve.

この場合、溶接熱影響部１４に組織変化を生じるような
再加熱、すなわち一度Ａ１変態点以下の温度まで冷却さ
れたところに再加熱によりＡ３変態点以上まで再び昇温
すると組織は焼ならし効果により微細結晶粒を呈する。
しかし、溶接線方向１５の熱影響部１４全域が同一な微
細化組織となるのではなく、熱源の付与位置が揺動軌跡
１０および溶接速度によつて随時変化し、さらにアーク
点弧範囲が狭小であるために、溶接線方向１５の熱影響
部１４全域にわたつて再加熱条件（温度、時間）を一定
にすることはできず、粗大化結晶と微細化結晶の混粒組
織となり、完全な組織改善法にはならない。さらに溶融
池１２の形状が溶接線１５に対し非対称となつていてこ
れは溶接ビード両端部１６，１６″のいずれか一方に相
当の凝固層が存在していることを意味し、電極揺動によ
つて溶接金属１３の溶融および凝固を繰返すと温度低下
したスラグを介してアーク９を点弧せねばならないため
、アーク９の安定性がそこなわれ、スラグ巻込み、融合
不良を生じ、欠陥の多い溶接部となる。以上、何れも多
量のスラグを生成するサブマージアーク浴接法における
４種の溶接条件を比較したが、溶接熱影響部１４に均一
な微細化組織を呈して高じん性が得られ、かつ健全な溶
接部１３を形成するには第５図ｂ１第６図ｂに示した場
合にのみに限定され、その特徴とするところは、溶接進
行方向と交叉するように電極を揺動する単電極サブマー
ジアーク法で溶接する際に、ビード幅となるビード両端
への熱源の付与が交４間欠的となるように電極揺動し、
かつビード幅を決定するビード両端位置が揺動したアー
クの到達ではじめて溶融し、溶接進行方向に対し後半部
の溶融池形状が溶接線に関して対称な先拡りをなすとこ
ろにあり、このため揺動周期にともなう再加熱効果によ
る熱影響部組織変化が生じないように熱源を与えること
にある。In this case, if the weld heat-affected zone 14 is reheated to cause a structural change, that is, once cooled to a temperature below the A1 transformation point, the structure is normalized by reheating to raise the temperature to the A3 transformation point or above. It exhibits fine crystal grains.
However, the entire heat affected zone 14 in the welding line direction 15 does not have the same refined structure, but the heat source application position changes from time to time depending on the swing trajectory 10 and the welding speed, and furthermore, the arc ignition range is narrow. Therefore, it is not possible to keep the reheating conditions (temperature, time) constant throughout the heat affected zone 14 in the weld line direction 15, resulting in a mixed grain structure of coarse and fine crystals, resulting in a complete It is not a method for organizational improvement. Furthermore, the shape of the molten pool 12 is asymmetrical with respect to the weld line 15, which means that there is a considerable solidified layer at either end 16, 16'' of the weld bead, which is caused by electrode fluctuation. Therefore, when the weld metal 13 is repeatedly melted and solidified, the arc 9 must be ignited through the slag whose temperature has decreased, which impairs the stability of the arc 9, causing slag entrainment, poor fusion, and defects. Above, we have compared four types of welding conditions in the submerged arc bath welding method, which all generate a large amount of slag. In order to form a welded part 13 that is both obtained and sound, it is limited to the cases shown in FIGS. 5b and 6b. When welding using the moving single electrode submerged arc method, the electrode is oscillated so that the heat source is applied intermittently to both ends of the bead, which corresponds to the bead width.
In addition, the bead ends at both ends, which determine the bead width, are melted only when the oscillating arc reaches them, and the shape of the molten pool in the latter half of the welding direction widens symmetrically with respect to the weld line. The purpose is to provide a heat source so that changes in the structure of the heat-affected zone do not occur due to the reheating effect associated with the dynamic cycle.

この発明の具体的な溶接条件の設定は次のとおりである
。The specific welding conditions of this invention are set as follows.

単電極サブマージアーク溶接法で電極ワイヤ３の揺動を
行うとき、溶接電流が５００Ａｍｐよりも小さい場合に
は十分なアーク熱が与えられず、母材１，１″および溶
接用フラツクス６の溶融が不均衡になつて融合不良、ス
ラグ巻込みなどの溶接欠陥が発生し、健全な溶接部は得
られない。さらに溶融池１２が溶接ビードの幅全体にわ
たつて形成されず、第５図、第６図および第７図のｄに
つき上記したような問題点が生じる。いつぼう、５００
Ａｆ１１ｐ以上では母材１，１２および溶接用フラツク
ス６の溶融が十分に行い得て、均一組成の溶接金属１３
が得られ、融合不良、スラグ巻込みなどの欠陥は皆無で
健全な溶接部が得られるとともに、高電流作用によつて
電極ワイヤ３の溶融量が増し、溶接能率の向上が達成さ
れる。揺勤行程端での許容最高入熱量については、溶融
池幅キビード幅を決定するように定めればよい。電極３
の移動単位長さ当りの平均人熱量Ｈ５は、第４図に示す
ごとく、電極揺動１サイクルに要するａ−＋ｂ−＋ｃ間
の電極移動距離ｌ（Ｃ７ｒＬ）とこの１サイクルに要す
る時間ｔ（Ｓｅｃ）の比率（１！／ｔ）を電極３の平均
移動速度ｖ′Ｃル庸１ｎ）として平均入熱量Ｒ（ＪＯｕ
ｌｅ／Ｃｍ）を求め、いつぽう溶接進行方向の単位長さ
当りの入熱量Ｈは溶接速度（ＱＶ冨１ｎ）、すなわち溶
接合車の移動速度から入熱量Ｈ（ＪＯＵｌｅ／ＣＴ！Ｌ
）を求めるものである。したがつて、電極３の揺動を行
えば溶接速度ｖよりも電極移動速度ｖ゛が大きくなり、
電極移動単位長さ当りの平均入熱量Ｒは溶接進行方向の
単位長さ当りの人熱量Ｈよりも小さくなる。この場合、
溶接熱影響部１４のじん性を向上させるには電極移動単
位長さ当りの平均入熱量Ｈ５に上限値が存在する。電極
移動単位長さ当りの平均入熱量Ｈ′は溶接熱影響部１４
のオーステナイト粒成長温度域での冷却速度に著しい影
響をおよぼす。When the electrode wire 3 is oscillated in the single-electrode submerged arc welding method, if the welding current is smaller than 500 Amps, sufficient arc heat will not be applied and the base metal 1,1'' and welding flux 6 will not melt. This imbalance causes weld defects such as poor fusion and slag entrainment, making it impossible to obtain a sound weld.Furthermore, the molten pool 12 is not formed over the entire width of the weld bead, and as shown in FIGS. The above-mentioned problem arises regarding d in Figures 6 and 7.
At Af11p or more, base metals 1, 12 and welding flux 6 can be sufficiently melted, and weld metal 13 with a uniform composition can be obtained.
A sound weld is obtained with no defects such as poor fusion or slag entrainment, and the amount of melted electrode wire 3 is increased due to the high current action, resulting in an improvement in welding efficiency. The maximum allowable heat input amount at the end of the swinging stroke may be determined so as to determine the molten pool width and the kibido width. Electrode 3
As shown in Fig. 4, the average amount of human heat per unit length of movement H5 is determined by the electrode movement distance l (C7rL) between a-+b-+c required for one cycle of electrode rocking and the time t( The average heat input amount R (JOu
le/Cm), and the heat input H per unit length in the welding direction is determined by the welding speed (QV 1n), that is, the moving speed of the welding wheel, and the heat input H (JOUle/CT!L).
). Therefore, if the electrode 3 is oscillated, the electrode moving speed v' becomes larger than the welding speed v,
The average amount of heat input R per unit length of electrode movement is smaller than the amount of human heat H per unit length in the welding direction. in this case,
In order to improve the toughness of the welding heat affected zone 14, there is an upper limit to the average heat input amount H5 per unit length of electrode movement. The average heat input H' per unit length of electrode movement is the welding heat affected zone 14
This has a significant effect on the cooling rate in the austenite grain growth temperature range.

この平均入熱量Ｈ５が２５，０００Ｊ０ｕ１ｅ／Ｃｍよ
りも大きい場合には溶接熱影響部１４に与えられる熱量
が大となつて、この部分のオーステナイト粒成長温度域
での冷却速度が遅くなる結果、オーステナイト粒は著し
く粗大化する。しかし、２５，０００Ｊ０ｕ１ｅノ？以
下では溶接熱影響部１４を余剰に加熱する熱量が削減さ
れる結果、オーステナイト粒成長温度域での冷却速度が
著しく速くなつて、オーステナイトは細粒となる。いつ
ぼう、溶接進行方向の単位長さ当りの入熱量Ｈは溶接能
率の向上および溶接工数の削減を図るには大入熱量にす
るほど好ましく、また冶金的効果としてはこの入熱量Ｈ
を大にしてもＨ′が２５，０００Ｊ０Ｕ１ｅＡ：１！Ｌ
以下であれば、溶接影響部１４のオーステナイト粒成長
温度域での冷却速度を遅らせる作用はほとんどなく、８
００℃から５００℃までの冷却時間のみがその入熱量Ｈ
に応じて長くなる結果、粗大な旧オーステナイト粒界に
晶出する粗大初析フエライトはほとんどなく、微細化組
織が得られ、高じん性化が達成できる。When this average heat input amount H5 is larger than 25,000 J0u1e/Cm, the amount of heat given to the weld heat affected zone 14 becomes large, and as a result, the cooling rate in this area in the austenite grain growth temperature range becomes slow, resulting in austenite The grains become significantly coarser. But 25,000J0u1e? Below, as a result of reducing the amount of heat that excessively heats the weld heat affected zone 14, the cooling rate in the austenite grain growth temperature range becomes significantly faster, and the austenite becomes finer grained. In order to improve welding efficiency and reduce welding man-hours, it is preferable to increase the heat input per unit length in the welding direction.
Even if you increase , H' is 25,000J0U1eA:1! L
If it is less than
Only the cooling time from 00℃ to 500℃ is the heat input H
As a result, there is almost no coarse pro-eutectoid ferrite crystallized at coarse prior austenite grain boundaries, a refined structure is obtained, and high toughness can be achieved.

この場合、電極移動単位長さ当りの平均入熱量Ｈ５を２
５，０００Ｊ０ｕ１ｅ々よりも小さくするほど溶接熱影
響部１４はより微細化組織を呈して、高じん性となるが
、この入熱量Ｈ′を極端に小さくすると溶接欠陥を発生
するようになる。すなわち、この入熱量Ｈ′を小さくす
るには電極３の平均移動速度ｖ′を大きくすることが必
要となる。移動速度Ｖｒを４５０ＣＩｎ／Ｍｉｎよりも
速くするとアークの安定性、電極ワイヤ３からの溶滴移
行および溶融池内の溶融金属の対流などがみだされると
ともに、第５図ｃにおける溶融池１２，１２″のごとく
、２個の連なつた形状となり、両溶融池１２，１２５の
連結部にはスラグ巻込み、融合不良を、またビード両端
部１６，１６′にはアンダーカツト、スラグ巻込みなど
を生じ、健全な溶接部は得られない。いつぼう、電極３
の平均移動速度Ｖ２を１００Ｃ！！Ｖｍｉｎよりも小さ
くすると、第５図ｄについて記載したように、溶融池１
２は溶接ビード１３の幅全体にわたつて形成されず、潜
弧アーク９の反対側のビード端部１６あるいは１６５の
いずれか一方の溶接金属はすでに凝固し、この部分に潜
弧アーク９が揺動軌跡１０に沿つて接近すると再び溶融
され、溶接熱影響部１４は焼ならしを受ける。In this case, the average heat input per unit length of electrode movement H5 is 2
As the heat input amount H' becomes smaller than 5,000J0u1e, the weld heat affected zone 14 exhibits a finer structure and becomes more tough, but if the heat input amount H' is made extremely small, welding defects will occur. That is, in order to reduce this heat input amount H', it is necessary to increase the average moving speed v' of the electrode 3. When the moving speed Vr is higher than 450CIn/Min, stability of the arc, droplet transfer from the electrode wire 3, convection of molten metal in the molten pool, etc. are improved, and the molten pools 12, 12 in FIG. '', the shape is two continuous pieces, and there is slag entrainment and poor fusion at the joint between both molten pools 12 and 125, and undercuts and slag entrainment at both ends 16 and 16' of the bead. This occurs and a sound weld cannot be obtained.
The average moving speed V2 of 100C! ! If it is smaller than Vmin, the molten pool 1
2 is not formed over the entire width of the weld bead 13, and the weld metal at either the bead end 16 or 165 on the opposite side of the submerged arc 9 has already solidified, and the submerged arc 9 is shaken in this area. When it approaches along the moving trajectory 10, it is melted again and the weld heat affected zone 14 undergoes normalization.

しかし、熱影響部全域にわたつて焼ならし条件を一定に
することはできず、粗大化結晶と微細化結晶の混粒組織
となり、完全な組織改善法にはならない。さらに電極の
揺動により溶接金属１３の溶融および凝固を繰返し、温
度低下したスラグを介してアーク９を点弧せねばならな
いためアークの安定性がそこなわれ、スラグ巻込み、融
合不良を生じ、欠陥の多い溶接部となる。したがつて、
溶接欠陥の防止および不均一な焼ならし効果の付与を避
けることから電極３の平均移動速度′は１００Ｃ７ｙ［
Ｎｉｎから４５０ｃ！Ｙｍｉｎの範囲にする必要がある
。電極３の平均移動速度ｖ′は電極揺動軌跡１０の１サ
イクルに要する電極移動長さｌとそれに要する時間ｔに
よつて定まり、ｊを大きくするほど、あるいはｔを短か
くするほど電極平均移動速度″は大きくなる。すなわち
、電極揺動１０の幅および揺動サイクル数によつて左右
されると考えてよい。揺動サイクル数は溶接ビードの蛇
行を防止する目的から、溶接ビード長さ１ＣＩ！Ｌ当り
に１．５サイクル以上の揺動を行うことが好ましい。電
極平均移動速度を一定として、揺動サイクル数と揺動幅
が溶融池形状におよぼす影響を実験で調べた結果、揺動
幅によつて溶融池形状が変化することが判明した。However, it is not possible to make the normalizing conditions constant over the entire heat-affected zone, resulting in a mixed grain structure of coarse and fine crystals, which is not a perfect method for improving the structure. Furthermore, the weld metal 13 is repeatedly melted and solidified by the swinging of the electrode, and the arc 9 must be ignited through the slag whose temperature has decreased, which impairs the stability of the arc, causing slag entrainment and poor fusion. This results in welds with many defects. Therefore,
In order to prevent welding defects and to avoid imparting uneven normalizing effects, the average moving speed of the electrode 3' is 100C7y[
450c from Nin! It is necessary to set it within the range of Ymin. The average movement speed v' of the electrode 3 is determined by the electrode movement length l required for one cycle of the electrode swing trajectory 10 and the time t required for it, and the larger j or the shorter t, the faster the average electrode movement. In other words, it can be considered that it depends on the width of the electrode oscillation 10 and the number of oscillation cycles.The number of oscillation cycles is determined by the weld bead length 1CI for the purpose of preventing meandering of the weld bead. !It is preferable to perform oscillation for 1.5 cycles or more per L.As a result of an experiment to investigate the effect of the number of oscillation cycles and oscillation width on the molten pool shape, with the average electrode moving speed kept constant, it was found that oscillation It was found that the shape of the molten pool changes depending on the width.

電極揺動幅を大きくするほどビード幅Ｗも大きくなり、
電極揺動１０した場合のビード幅ＷＯと揺動しない場合
のビード幅Ｗｓの比率（ＷＯ／Ｗｓ）に適正範囲が存在
する。ＷＯ／Ｗｓが２．５よりも大きくなるように揺動
幅を与えると第５図、第６図のｃあるいはｄに記載した
ような溶融池１２形状を形成し、スラグ巻込み、融合不
良、アンダーカツトを生じ、また溶接熱影響部１４″は
焼ならし効果によつて細粒化されるために、熱影響部全
域を均一な微細化組織にすることは困難となる。また、
ＷＯ／Ｗｓが１．３よりも小さくなるように揺動幅を与
えると第５図、第６図のａに記載したような溶融池１２
を形成し、母板１，Ｐの二次溶融を生じ、溶接金属１３
の凝固開始位置は電極３位置よりも極めて後方側となる
。このために、溶接熱影響部１４は高温度にさらされて
いる時間が長くなる結果、熱影響部１４の冷却速度は著
しく遅くなつて粗大化した組織を呈するとともに、熱影
響幅ｈも大となり、じん性は劣化する。したがつて、一
定溶接条件（溶接電流、電圧、溶接速度、溶接材粕）で
電極揺動した場合のビード幅ＷＯと揺動しない場合のビ
ード幅Ｗｓの比率（ＷＯ／Ｗｃ）を１．３〜２．５の範
囲にすることによつて、第５図、第６図のｂ法に記載し
たような溶接部が得られ、溶接欠陥は全くなく、かつ溶
接熱影響部１４全域は均一な微細化組織を呈して高じん
性化が遅成できる。なお、電極揺勤行程両端での停止時
間は、アークがビード幅となるビード両端に点弧してい
る時間を短かくし、溶接熱影響部の過剰加熱を防止する
ことから１秒以下が好ましい。The larger the electrode swing width, the larger the bead width W.
There is an appropriate range for the ratio (WO/Ws) of the bead width WO when the electrode is oscillated by 10 degrees and the bead width Ws when the electrode is not oscillated. If the oscillation width is set so that WO/Ws is larger than 2.5, the shape of the molten pool 12 as shown in c or d of FIGS. 5 and 6 will be formed, resulting in slag entrainment, poor fusion, and Undercuts occur, and the weld heat affected zone 14'' is grain-refined due to the normalizing effect, making it difficult to make the entire heat affected zone a uniformly refined structure.
If the oscillation width is given so that WO/Ws is smaller than 1.3, the molten pool 12 as shown in a of FIGS. 5 and 6 will be formed.
is formed, secondary melting of the base plate 1, P occurs, and weld metal 13
The coagulation start position is extremely rearward than the electrode 3 position. For this reason, the welding heat affected zone 14 is exposed to high temperatures for a longer time, and as a result, the cooling rate of the heat affected zone 14 becomes significantly slower, resulting in a coarser structure, and the heat affected width h becomes larger. , the toughness deteriorates. Therefore, the ratio (WO/Wc) of the bead width WO when the electrode is oscillated and the bead width Ws when the electrode is not oscillated under constant welding conditions (welding current, voltage, welding speed, welding material waste) is 1.3. By setting the temperature in the range of 2.5 to 2.5, a welded part as shown in method b in Figs. It exhibits a fine structure and the toughness can be delayed. The stopping time at both ends of the electrode swinging stroke is preferably 1 second or less in order to shorten the time during which the arc is ignited at both ends of the bead, which is the bead width, and to prevent excessive heating of the welding heat affected zone.

この発明の効果をさらに明瞭に示すため、つぎに実施例
により説明する。In order to demonstrate the effects of this invention more clearly, examples will be described below.

まず、各実施例における溶液に供した材刺の化学組成を
第１表に、溶接条件を第２表にまとめて示す。実施例
１ 第１表に示す板厚３８ｍ！の５０１＜９／Ｍｌ２級高張
力鋼板Ｇを径４．０ｍｍのソリツドワイヤＡと溶融型フ
ラツクスＤを使用して、第２表の条件で従来法・・およ
び本発明法のサブマージアーク溶接を行い、溶接部の機
械的特性と溶接能率を比較した。First, Table 1 summarizes the chemical composition of the material used in the solution in each Example, and Table 2 summarizes the welding conditions. Example
1 The plate thickness shown in Table 1 is 38m! 501<9/Ml2 class high tensile strength steel plate G was subjected to submerged arc welding using the conventional method and the present invention method under the conditions shown in Table 2 using solid wire A with a diameter of 4.0 mm and fusion type flux D. The mechanical properties of welds and welding efficiency were compared.

その結果が第３表である。この発明によればこの発明の
溶接入熱量とほぼ等しい従来法Ｈは溶接能率はほとんど
変わらないが、溶接熱影響部のじん性の比較ではこの発
明によるものが極めてすぐれている。The results are shown in Table 3. According to the present invention, the welding efficiency of the conventional method H, which is almost equal to the welding heat input of the present invention, is almost the same, but the method according to the present invention is extremely superior when compared with respect to the toughness of the weld heat affected zone.

また、従来法Ｈは電極揺動を行つているが、平均人熱量
Ｈ５が大きいため十分なじん性改善とはなつていない。
なお、この発明の溶接部にはアンダーカツト、スラグ巻
込み、融合不良などの欠陥は全く認められず健全な溶接
部が得られ、強度、延性ともに良好であつた。
★【：実施例 ２第
１表に示す板厚２５ｍＴＩＬの５０ｋｇ／Ｍｍ２級低温
用鋼板Ｈを径２．４ｍ１のソリツドワイヤＢと焼結型フ
ラツクスＥを使用して、第２表の条件で従来法および本
発明法のサブマージアーク溶接を行い、溶接部の機械的
特性を比較した。Further, although conventional method H performs electrode rocking, the average human heat value H5 is large, so the toughness is not sufficiently improved.
In addition, no defects such as undercuts, slag entrainment, or poor fusion were observed in the welded joints of this invention, and a sound welded joint was obtained, with good strength and ductility.
★[: Example 2 A 50kg/Mm2 grade low-temperature steel plate H with a plate thickness of 25mTIL shown in Table 1 was processed using the conventional method under the conditions shown in Table 2 using solid wire B with a diameter of 2.4m1 and sintered flux E. Then, submerged arc welding using the method of the present invention was performed, and the mechanical properties of the welded parts were compared.

この結果が第４表で、溶接部の横断面形状が第８図であ
る。なお、従来法は二電極溶接法で先行電極は揺動せず
、後行電極のみ揺動し、極間距離は８０ｍｍで２つの溶
融池を形成させる方法である。この発明は従来法に比較
して、いずれの位置においてもすぐれたじん性を示して
いる。The results are shown in Table 4, and the cross-sectional shape of the welded portion is shown in FIG. The conventional method is a two-electrode welding method in which the leading electrode does not oscillate, only the trailing electrode oscillates, and the distance between the electrodes is 80 mm to form two molten pools. This invention shows superior toughness at all positions compared to the conventional method.

従来法のじん性植に相当のバラツキがあり、これら試片
について熱影響部組織を観察した結果、高じん性の試片
は後行電極による焼ならし効果を受け、微細組織を呈し
ていたが、低じん性の試片は該電極による焼ならし効果
はほとんどなく、大部分が粗大化した組織が残存してい
た。すなわち、先行電極の溶接によつて生じた熱影響部
１４と後行電極によつて生じた熱影響部１４が合致した
個所１４′は焼ならし効果によつて再粒化されるが、他
の部分１４は焼ならしを受けないために粗大化組織を呈
する。また、後行電極はこの発明のごとき揺動を付加し
ているが、先行電極の溶接熱が残存し、予熱効果によつ
て後行電極による熱影響部の冷却速度を速める効果はほ
とんどなく、熱影響部幅ｈも広く、組大化組織（粗大初
析フエライト＋上部ベーナイト）となつていることを確
認した。この発明での溶接熱影響部１４の組織は粗大化
した初析フエラィトはほとんどなく、微細組織であつた
。There was considerable variation in the toughness of the conventional method, and as a result of observing the heat-affected zone structure of these specimens, it was found that the highly tough specimens had a fine structure due to the normalizing effect of the trailing electrode. However, in the specimen with low toughness, there was almost no normalizing effect due to the electrode, and most of the specimens had a coarsened structure remaining. That is, the area 14' where the heat-affected zone 14 created by the welding of the leading electrode and the heat-affected zone 14 created by the trailing electrode coincide is regrained due to the normalizing effect; The portion 14 exhibits a coarsened structure because it is not normalized. In addition, although the trailing electrode is given oscillation as in the present invention, the welding heat of the leading electrode remains, and the preheating effect has almost no effect on speeding up the cooling rate of the heat affected zone by the trailing electrode. It was confirmed that the heat-affected zone width h was wide, and that it had a large-sized structure (coarse pro-eutectoid ferrite + upper bainite). The structure of the weld heat affected zone 14 in this invention was a fine structure with almost no coarse pro-eutectoid ferrite.

比較法は溶融池形状が第５図ｄのようになり、融合不良
、スラグ巻込みを生じ、性能拘？刑まできなかつた。ま
た、従来法に発生したスラグ巻込みは、後行電極の溶接
時に生じたもので、先行電極での溶接時に生じた低温度
のスラグを、比較的低電流の後行電極が十分に溶融しき
れずに残留したものである。実施例 ３ 第１表に示す板厚４０ｍ１の６０ｋｇ／Ｍｌ２級高張力
鋼板１を径２．４１＆ｍのソリツドワイヤＢと焼結型フ
ラツクスＦを使用して、第２表の条件で従来法および本
発明法のサブマージアーク溶接を行い、溶接部の機械的
特性と溶接能率を比較した。In the comparative method, the shape of the molten pool is as shown in Figure 5d, resulting in poor fusion, slag entrainment, and performance issues. I didn't even get to the punishment. In addition, the slag entrainment that occurred in the conventional method occurred during welding with the trailing electrode, and the trailing electrode with a relatively low current sufficiently melted the low-temperature slag generated during welding with the leading electrode. This is what remains. Example 3 A 60kg/Ml2 grade high-strength steel plate 1 with a thickness of 40m1 shown in Table 1 was prepared using the conventional method and the present invention under the conditions shown in Table 2 using solid wire B with a diameter of 2.41mm and sintered flux F. The mechanical properties and welding efficiency of the weld were compared using submerged arc welding using the method.

その結果が第５表である。この発明で溶接熱影響部のじ
ん性は従来法よりも著しくすぐれており、また溶接能率
は従来法よりも高入熱量で溶接したために高能率である
。Table 5 shows the results. In this invention, the toughness of the weld heat affected zone is significantly superior to that of the conventional method, and the welding efficiency is high because welding is performed with a higher heat input than the conventional method.

なお、この発明の溶接部には溶接欠陥は全く認められず
、良好であつた。従来法とこの発明における溶接熱影響
部の顕微鏡組織を第９図Ａ，ｂに比較して示したように
、この発明法は極めて微細な組織を呈している。市実施
例 ４ 第１表に示す板厚５０Ｅ１の８０ｋｇ／詣２級調質高張
力鋼Ｊを径３．２ｍｍのソリツドワイヤＣと焼結型フラ
ツクスＦを使用して、第２表の条件で従来法および本発
明法のサブマージアーク溶接を行い、溶接部の機械的特
性と溶接能率を比較した。In addition, no welding defects were observed in the welded parts of the present invention, and the welded parts were in good condition. As shown in FIGS. 9A and 9B, which compare the microstructures of the weld heat-affected zone in the conventional method and the present invention, the present method exhibits an extremely fine structure. City Example 4 80kg/Mai 2 grade heat-treated high tensile strength steel J with a plate thickness of 50E1 shown in Table 1 was made using a solid wire C with a diameter of 3.2 mm and a sintered flux F under the conditions shown in Table 2. Submerged arc welding was performed using the method and the method of the present invention, and the mechanical properties and welding efficiency of the weld were compared.

その結果が第６表である。この発明の溶接熱影響部じん
性は従来法よりも著しくすぐれており、かつ熱影響部の
軟化の程度が小さくなつているために引張強度も従来法
よりも高い値を示している。The results are shown in Table 6. The weld heat-affected zone toughness of the present invention is significantly superior to that of the conventional method, and since the degree of softening of the heat-affected zone is reduced, the tensile strength also exhibits a higher value than that of the conventional method.

溶接能率は従来法よりも高人熱量で溶接したために高能
率であることがわかる。なお、本発明法の溶接部には切
陥は全く認められず、健全な溶接部が得られた。さらに
Ｂａｃｋｉｎｇｓｉｄｅの最終ビードの溶接熱影響部の
平均オーステナイト粒を測定した結果、第１０図のよう
にこの発明では従来法よりも高人熱量で溶接したにもか
かわらず、極めて細粒なオーステナイト粒になつている
ことがわかる。溶接終了後、応力除去熱処理（加熱保持
時間６５『ＣＸ４ｈｒ．）を行い、溶接熱影響部粗大化
域の粒界われについて調査した結果、従来法ではわれが
数ケ所認められたが、本発明法では全く認められず、健
全な溶接部が得られた。It can be seen that the welding efficiency is higher because the welding requires a higher amount of human heat than the conventional method. It should be noted that no notches were observed in the welded area obtained by the method of the present invention, and a sound welded area was obtained. Furthermore, as a result of measuring the average austenite grains in the weld heat-affected zone of the final bead on the backing side, as shown in Figure 10, even though this invention welded with a higher human heat amount than the conventional method, extremely fine austenite grains were obtained. I can see that I am getting used to it. After the completion of welding, stress relief heat treatment (heating holding time 65 "CX4hr.") was carried out, and as a result of investigating grain boundary cracks in the weld heat affected zone coarsening region, several cracks were observed with the conventional method, but with the present method. No defects were observed at all, and a sound weld was obtained.

上述のように従来の溶接方法では溶接人熱量の増大にと
もなつて溶接熱影響部、とくにポンド近傍はじん性が著
しく劣化する傾向にある。As mentioned above, in conventional welding methods, the toughness of the welding heat affected zone, particularly in the vicinity of the pound, tends to deteriorate significantly as the amount of heat exerted by the welder increases.

したがつて、これを防止するために溶接能率、溶接コス
トを儀性にして谷種鋼材に適応した制限入熱量内で施工
されていた。しかし、この発明は従来法ごとき、人熱量
の制限は不要で、軟鋼、高張力鋼、耐熱鋼および低温用
鋼などを高能率な大人熱量で溶接しても、オーステナイ
ト粒成長温度域での冷却速度が著しく速く、かつ８００
℃から５００℃までは溶接人熱量に相当した冷却速度に
なるため、溶接熱影響部のオーステナイト粒は細粒で微
細組織を呈して高じん性で、かつぜい化がほとんど認め
られない溶接部が得られる。Therefore, in order to prevent this, welding efficiency and welding costs have been taken into account and work has been carried out within a heat input limit adapted to the grade steel material. However, unlike conventional methods, this invention does not require the restriction of human heat, and even when welding mild steel, high-strength steel, heat-resistant steel, low-temperature steel, etc. with a highly efficient adult heat, cooling in the austenite grain growth temperature range is not required. The speed is extremely fast and 800
From ℃ to 500℃, the cooling rate is equivalent to the amount of heat consumed by the welder, so the austenite grains in the weld heat-affected zone are fine and have a microstructure, resulting in high toughness and a welded part with almost no embrittlement. is obtained.

しかも揺動アークにもかかわらずスラグ巻込み、融合不
良、アンダーカツトは発生せず健全な溶接部が得られる
。さらにこの発明でＺＯは結晶微細化作用が焼もどし効
果によるものではないので、溶接部のいかなる個所を検
査しても良好な機械的特性が得られるとともに、溶接熱
影響部の炭化物、あるいは窒化物の析出を最小限に抑制
できるので、特殊鋼の継手溶接にも適用できる。Furthermore, despite the oscillating arc, no slag entrainment, poor fusion, or undercut occurs, and a sound weld can be obtained. Furthermore, in this invention, the crystal refinement effect of ZO is not due to the tempering effect, so good mechanical properties can be obtained even when inspecting any part of the weld, and carbides or nitrides in the weld heat affected zone can be inspected. Since precipitation of can be minimized, it can also be applied to special steel joint welding.

また、この発明は８０Ｋｇ／Ｍｍ２級高張力鋼や耐熱鋼
の溶接部の継手性能を確保するために、溶接後熱処理を
行つても、微細組織を呈しているために粒界われは発生
せず、従来の溶接入熱量制限策は不要となり、従来不可
とされていた大入熱溶接が達成できる。この発明は多層
盛溶接法のみならず、片面溶接法、一層盛溶接法コール
ドワイヤ併用溶接法に応用でき、その個所は傾斜継手部
、狭開先継手部、隅肉継手部などに適用できる。In addition, in order to ensure joint performance of welded parts of 80Kg/Mm2 class high tensile strength steel and heat-resistant steel, this invention has a microstructure that does not cause grain boundary cracking even if heat treatment is performed after welding. , conventional welding heat input limiting measures are no longer necessary, and high heat input welding, which was previously considered impossible, can be achieved. This invention can be applied not only to multi-layer welding, but also to single-sided welding, single-layer welding, and combined cold wire welding, and can be applied to inclined joints, narrow gap joints, fillet joints, etc.

また、電極ワイヤとしてフラツクスを内蔵した複合ワイ
ヤを用いることができるのは勿論であり、開先内にカツ
トワイヤや鉄分などを充填した方法にも適用できる。Furthermore, it goes without saying that a composite wire containing flux can be used as the electrode wire, and it is also applicable to a method in which the groove is filled with cut wire, iron, or the like.

【図面の簡単な説明】[Brief explanation of the drawing]

第１図は、従来法の溶融池形状の模式図、第２図は、第
１図１位置での溶接熱影響部の冷却曲線、第３図は、本
発明溶接方法の施工要領説明図、第４図は本発明法に適
用できる電極揺動軌跡の説明図、第５図は各執揺動法に
よる溶融池形状の模式図、第６図は各踵揺動法による溶
融池断面形伏、第７図は第５図での溶接熱影響部の冷却
曲線、第８図は実施例２での溶接部横断面比較図、第９
図Ａ，ｂは従来法及び本発明法による溶接熱影響組織の
顕微鏡写真図、第１０図は実施例４での溶接熱影響部平
均オーステナイト粒径グラフである。FIG. 1 is a schematic diagram of the molten pool shape of the conventional method, FIG. 2 is a cooling curve of the weld heat-affected zone at position 1 in FIG. Figure 4 is an explanatory diagram of the electrode rocking locus that can be applied to the method of the present invention, Figure 5 is a schematic diagram of the molten pool shape by each rocking method, and Figure 6 is the cross-sectional shape of the molten pool by each heel rocking method. , FIG. 7 is a cooling curve of the weld heat affected zone in FIG. 5, FIG. 8 is a cross-sectional comparison diagram of the welded part in Example 2, and FIG.
Figures A and b are micrographs of weld heat-affected structures obtained by the conventional method and the method of the present invention, and FIG. 10 is a graph of the average austenite grain size of the weld heat-affected zone in Example 4.

Claims (1)

【特許請求の範囲】 １ 溶接線に対し交差する向きに電極を揺動させつつ溶
接線に沿つて進行させる単電極サブマージアーク溶接に
際し、つくろうとするビード幅に合致した横幅において
急深をなす溶融池の前縁を逐次に更新するに足る工程長
さの揺動を強制し、該溶融池の追尾側に、溶接線に関し
これに沿う先拡りの対称形をなす凝固を導くこと、を特
徴とする単電極揺動サブマージアーク溶接法。 ２ つくろうとするビード幅に合致する溶融池の横幅が
、溶接入熱条件を同じくして電極揺動を省略したときに
得られるビード幅に対して１．２〜２．５の倍率である
ものとする、１記載の方法。 ３ 溶接線に沿う電極の平均移動速度が１００〜４５０
ｃｍ／ｍｉｎでかつ、電極移動径路上での平均入熱量が
、単位長さ１ｃｍ当り、２５，０００Ｊ以下である、１
又は２記載の方法。[Scope of Claims] 1. During single-electrode submerged arc welding in which the electrode is oscillated in a direction crossing the weld line and progresses along the weld line, melting that suddenly deepens at a width that matches the bead width to be created is performed. It is characterized by forcing the oscillation of a process length sufficient to successively update the leading edge of the molten pool, and inducing solidification on the tracking side of the molten pool in a symmetrical shape with a widening tip along the weld line. Single electrode oscillating submerged arc welding method. 2 The width of the molten pool that matches the bead width to be created is a 1.2 to 2.5 multiplier of the bead width obtained when the welding heat input conditions are the same and electrode rocking is omitted. The method described in 1. 3 The average moving speed of the electrode along the welding line is 100 to 450
cm/min and the average heat input on the electrode moving path is 25,000 J or less per unit length 1 cm, 1
Or the method described in 2.