JPH0451279B2 - - Google Patents
Info
- Publication number
- JPH0451279B2 JPH0451279B2 JP29508787A JP29508787A JPH0451279B2 JP H0451279 B2 JPH0451279 B2 JP H0451279B2 JP 29508787 A JP29508787 A JP 29508787A JP 29508787 A JP29508787 A JP 29508787A JP H0451279 B2 JPH0451279 B2 JP H0451279B2
- Authority
- JP
- Japan
- Prior art keywords
- welding
- flux
- slag
- bead
- weld metal
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
- 238000003466 welding Methods 0.000 claims description 77
- 230000004907 flux Effects 0.000 claims description 55
- 229910004298 SiO 2 Inorganic materials 0.000 claims description 22
- 239000002245 particle Substances 0.000 claims description 20
- 229910010413 TiO 2 Inorganic materials 0.000 claims description 14
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims description 12
- GWEVSGVZZGPLCZ-UHFFFAOYSA-N Titan oxide Chemical compound O=[Ti]=O GWEVSGVZZGPLCZ-UHFFFAOYSA-N 0.000 claims description 12
- 239000000203 mixture Substances 0.000 claims description 12
- 229910052760 oxygen Inorganic materials 0.000 claims description 12
- 229910004261 CaF 2 Inorganic materials 0.000 claims description 6
- 229910052681 coesite Inorganic materials 0.000 claims description 6
- 229910052906 cristobalite Inorganic materials 0.000 claims description 6
- 239000000377 silicon dioxide Substances 0.000 claims description 6
- 235000012239 silicon dioxide Nutrition 0.000 claims description 6
- 229910052682 stishovite Inorganic materials 0.000 claims description 6
- 229910052905 tridymite Inorganic materials 0.000 claims description 6
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 claims description 4
- 229910052593 corundum Inorganic materials 0.000 claims description 4
- 229910001845 yogo sapphire Inorganic materials 0.000 claims description 4
- 229910018072 Al 2 O 3 Inorganic materials 0.000 claims description 3
- 239000011324 bead Substances 0.000 description 62
- 239000002893 slag Substances 0.000 description 55
- 239000002184 metal Substances 0.000 description 29
- 229910052751 metal Inorganic materials 0.000 description 29
- 230000000694 effects Effects 0.000 description 14
- 239000010410 layer Substances 0.000 description 13
- 239000002356 single layer Substances 0.000 description 12
- 239000001257 hydrogen Substances 0.000 description 9
- 229910052739 hydrogen Inorganic materials 0.000 description 9
- 238000000034 method Methods 0.000 description 9
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 8
- 229910000831 Steel Inorganic materials 0.000 description 8
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 8
- 230000007547 defect Effects 0.000 description 8
- 239000001301 oxygen Substances 0.000 description 8
- 239000010959 steel Substances 0.000 description 8
- 238000007689 inspection Methods 0.000 description 7
- 238000002844 melting Methods 0.000 description 5
- 230000008018 melting Effects 0.000 description 5
- 238000005336 cracking Methods 0.000 description 4
- 230000006866 deterioration Effects 0.000 description 4
- 239000007789 gas Substances 0.000 description 4
- 230000000052 comparative effect Effects 0.000 description 3
- 230000007423 decrease Effects 0.000 description 3
- 238000003475 lamination Methods 0.000 description 3
- 238000002156 mixing Methods 0.000 description 3
- WUKWITHWXAAZEY-UHFFFAOYSA-L calcium difluoride Chemical compound [F-].[F-].[Ca+2] WUKWITHWXAAZEY-UHFFFAOYSA-L 0.000 description 2
- 229910001634 calcium fluoride Inorganic materials 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 239000000155 melt Substances 0.000 description 2
- 230000035515 penetration Effects 0.000 description 2
- 239000002994 raw material Substances 0.000 description 2
- 238000000926 separation method Methods 0.000 description 2
- 239000000126 substance Substances 0.000 description 2
- 238000010521 absorption reaction Methods 0.000 description 1
- 229910000272 alkali metal oxide Inorganic materials 0.000 description 1
- 238000005275 alloying Methods 0.000 description 1
- 239000011230 binding agent Substances 0.000 description 1
- 230000005540 biological transmission Effects 0.000 description 1
- 239000011362 coarse particle Substances 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 239000002178 crystalline material Substances 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 238000011156 evaluation Methods 0.000 description 1
- 239000010419 fine particle Substances 0.000 description 1
- 238000010304 firing Methods 0.000 description 1
- 230000004927 fusion Effects 0.000 description 1
- 150000002431 hydrogen Chemical class 0.000 description 1
- 238000009863 impact test Methods 0.000 description 1
- 238000011835 investigation Methods 0.000 description 1
- CPLXHLVBOLITMK-UHFFFAOYSA-N magnesium oxide Inorganic materials [Mg]=O CPLXHLVBOLITMK-UHFFFAOYSA-N 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 235000019353 potassium silicate Nutrition 0.000 description 1
- 239000000843 powder Substances 0.000 description 1
- 230000002787 reinforcement Effects 0.000 description 1
- 238000011160 research Methods 0.000 description 1
- NTHWMYGWWRZVTN-UHFFFAOYSA-N sodium silicate Chemical compound [Na+].[Na+].[O-][Si]([O-])=O NTHWMYGWWRZVTN-UHFFFAOYSA-N 0.000 description 1
- 238000007711 solidification Methods 0.000 description 1
- 230000008023 solidification Effects 0.000 description 1
- 238000012360 testing method Methods 0.000 description 1
- 230000000007 visual effect Effects 0.000 description 1
Landscapes
- Nonmetallic Welding Materials (AREA)
Description
(産業上の利用分野)
この発明は、比較的薄肉の鋼板の単層溶接から
厚鋼板の多層溶接まで適用できるサブマージアー
ク溶接用溶融型フラツクス、とくに多層溶接では
開先内でのスラグはく離性、ビード外観が良好
で、しかも機械的性能にも優れた溶接金属が得ら
れるサブマージアーク溶接用溶融型フラツクスに
関するものである。
(従来の技術)
鋼板の自動溶接方法としては、サブマージアー
ク溶接方法、MIG溶接方法およびCO2溶接方法な
どがあるが、その中でもサブマージアーク溶接方
法は溶着量が多く、しかも深溶け込みが得られる
ため、能率面、得られる継手の信頼性の面で優れ
た溶接方法と考えられ、とくに厚鋼板の溶接に広
く用いられている。
ところでサブマージアーク溶接用フラツクスに
は焼成型と溶融型とがあり、前者は生の原材料を
水ガラスなどのバインダを用いて造粒、焼成した
もので、フラツクス中にガス発生源を添加して、
アーク中の水素分圧を低減することにより拡散性
水素量を減らしたり、フラツクスから合金元素の
添加ができるなどの利点がある反面、吸湿し易い
ことの他に、多電極高速溶接がむずかしいなどの
欠点がある。
一方、溶融型フラツクスは、原材料を溶融後、
ガラス状に凝固させたものを粉砕することにより
製造されるが、通常はガラス状になつているため
吸湿しにくく、しかも多電極高速溶接に適してい
るという利点がある。
これらはそれぞれの特長が活かされるように目
的に応じて使い分けされている。たとえばUOE
パイプの如く溶接速度が、工場全体の生産能力に
大きく影響する場合は、多電極高速溶接法を採用
する必要があり、一般的には溶融型フラツクスを
用いた多電極両面1層溶接方法が適用されてい
る。この場合、フラツクスに要求される特性は、
高速でも欠陥の無い良好なビードが得られるこ
と、および溶接金属の機械的性能に優れているこ
とである。
ところが厚肉の鋼板の如く多層溶接方法をとら
ざるを得ない場合には、実溶接時間よりもむしろ
スラグ除去などに要する時間の方が全体の能率に
大きく影響し、従つてスラグはく離性の悪いフラ
ツクスでは、その除去に多大の時間と労力を要
し、好ましくない。
前述の如く、UOEパイプのような長手シーム
溶接をシステム化された工場で行う場合には、溶
接速度が生産性に大きく影響するが、鉄骨、橋梁
など形状が様々でありまた単品に近いものでは確
実にスラグがはく離でき、しかもビード形状が良
好で欠陥発生の無い溶接が行えれば能率は良好と
なる。たとえば多層溶接において、はく離性の悪
いフラツクスを使用すると、スラグ除去に多大の
時間と労力を要するばかりではなく、除去不完全
の場合には取り残したスラグが原因となつて、溶
込み不良やスラグ巻き込みなどの溶接欠陥が発生
し易いという問題がある。
スラグのはく離性は、開先角度が狭い場合、と
くに劣化しやすく、通常のX開先では最もきつい
初層溶接のスラグはく離性が問題となることが多
い。
すなわち、従来、多層溶接用として一般に用い
られているSiO2−MnO系、SiO2−MnO−CaO系
フラツクスでは開先内でスラグはく離性を良くす
るために、開先角度を60゜以上まで広げ、しかも
ビード形状の劣化を防止するために低速、低入熱
溶接とすることが多く、とても能率がいいとはい
えなかつた。
スラグはく離を改善する方法としては、SiO2
−MnO系フラツクスにPbOを少量添加する方法
が特開昭53−133543号公報に提案されているが、
この方法ではPbの人体への影響が心配されると
いう問題がある。
一方スラグはく離性を改善し、狭開先溶接に適
用できるフラツクスとしてすでにいくつかの提案
がなされている。たとえば特開昭55−10356号、
同55−10357号および同55−10358号各公報などで
あり、これらはフラツクスの成分範囲を規定し、
狭開先溶接が可能となるようにしたものである
が、SiO2を低減し、Al2O3を多量に添加している
ため、フラツクス融点が高くビード幅が出にくい
という問題があり、通常の単層または多層の突合
せ溶接に適用した場合はSiO2の多いフラツクス
に比較して幅が狭く、結果的にビード高さの高い
ビードとなりやすく外観上好ましくない。
ここにスラグはく離性を改善する要件としては
以下に示す項目が考えられる。
(1) スラグの体積収縮量と溶接金属体積収縮量の
差が大きいこと。
(2) スラグと溶接金属との付着力が小さいこと。
(3) ビード断面形状が凹型で機械的にスラグを拘
束しないこと。
(1)に関しては、一般的にはスラグの熱膨張係数
が大きいほうが有利であり、そのためにはスラグ
の分離凝固温度は高いことが望ましいが、高すぎ
る場合にはビード幅が出にくくなることから、こ
の点を勘案して選定しなければならない。
(2)に関しては、スラグと溶接金属間の界面張力
と密接に関係し、界面エネルギーが増加するほど
付着力は小さくなる。
(3)に関しては、凸状ビードの場合エツジ部にア
ンダカツトが生じ、それが機械的にスラグを拘束
してはく離性をさまたげることからビード形状は
フラツトか凹型にする必要がある。このビード形
状には溶接条件も関係するため、適切な条件を選
定することはもちろん重要である。
さらにスラグのはく離性が良好であることの
他、溶接金属のじん性が良好であること、さらに
は低温割れが発生しないように溶接金属中拡散性
水素量が少ないことなどが具備条件として挙げら
れる。
(発明が解決しようとする問題点)
この発明は、サブマージアーク溶接において単
層溶接時に幅広の良好なビード外観を得ることは
勿論のこと、多層溶接時でもスラグはく離性が良
好で、しかも外観ならびに溶接金属の機械的性能
も良好ならしめる溶融型フラツクスを提案するこ
とを目的とする。
(問題点を解決するための手段)
まず、この発明の解明経緯について説明する。
さて発明者らは、種々の組成を有するフラツク
スを溶製し、単層溶接時のビード外観、形状、な
らびに比較的角度の小さい開先内多層溶接時にお
けるスラグはく離性、ビード形状および溶接金属
のじん性などを総合的に検討した。
その結果SiO2,TiO2,MgOを比較的多量に含
み、しかもSiO2が一定の関係を満足していると
きに、ビード幅が広く、またフラツクス融点をそ
れほど高くしなくても開先内でのスラグはく離性
が極めて良好で、しかもビード断面形状もフラツ
トまたは凹型になることを見い出した。そのとき
のスラグはほぼガラス質で顕微鏡観察、X線観察
により、ごく少量のTiO2系の結晶質が認められ
たが、このガラス質スラグの中にわずかに存在す
る結晶質がスラグ全体の体積収縮量を大きくして
いることが考えられる。この観点に立てば、スラ
グ全体を結晶質にすることにより安定したスラグ
はく離性が得られると考えられるが、そのために
はTiO2やAl2O3を増やす必要が生じるため、結果
的にスラグ融点が高くなり、ビード幅が出なくな
るとともにフラツクス中の水素量が増加すること
から、これらをむやみに増やさない方が良いこと
も判明した。
加えて、SiO2はビード幅を広くする上で一定
量以上添加しなければならないこと、また溶接金
属じん性の面からMgOを少し多めに、さらに
CaO,CaF2も一定量以上添加して溶接金属中酸
素量を低減する必要のあることも判つた。このよ
うにして、試作したフラツクスは、単層溶接時に
良好なビードが得られるとともに、多層溶接時の
開先内スラグはく離性も良好であつたが、フラツ
クス粒度との関係でさらに検討したところ、一定
の粒度条件を有しているフラツクスの方が形状の
より良好なビードが得られることも併せて見い出
した。
この発明は、上記の知見に立脚するものであ
る。
すなわち、この発明は、
SiO2:20〜30wt%(以下単に%で示す)
TiO2:13〜20%でかつ
SiO2/TiO2=1.0〜1.55、
Al2O3:2〜8%
MnO:7〜15%
MgO:12〜20%
CaO:5〜17%
CaF2:5〜15%および
Na2O,K2Oのうちから選んだ一種又は二種の
合計:0.1〜2.0%
の組成になるフラツクスであつて、粒子径が
351μmより粗粒のものが全体の5%以下、74μm
より細粒のものが全体の5〜20%を占めることか
らなるサブマージアーク溶接用溶融型フラツクス
である。
またこの発明は、
SiO2:20〜30%
TiO2:13〜20%でかつ
SiO2/TiO2=1.0〜1.55、
Al2O3:2〜8%
MnO:7〜15%
MgO:12〜20%
CaO:5〜17%
B2O3:1.0%以下
CaF2:5〜15%および
Na2O,K2Oのうちから選んだ一種又は二種合
計:0.1〜2.0%
の組成になるフラツクスであつて、粒子径が
351μmより粗粒のものが全体の5%以下、74μm
より細粒のものが全体の5〜20%を占めることか
らなるサブマージアーク溶接用溶融型フラツクス
である。
(作用)
まずこの発明において、成分組成を上記の範囲
に限定した理由について説明する。
SiO2:20〜30%
SiO2は、フラツクスを構成する重要な成分で
ビード外観、溶接金属のじん性などに大きな影響
を与える。配合量が20%未満ではビード幅が出に
くく、外観上好ましくないビードとなり、一方30
%を超えると溶接金属中酸素量が増加してじん性
を劣化させることから、20〜30%にする必要があ
る。
TiO2:13〜20%
TiO2は、開先内でのスラグはく離性に大きく
影響し、13%未満ではスラグがビードにこびり付
き易く、一方20%を超えるとスラグが全面的に結
晶質となつてビード幅が出にくくなり、また溶接
金属中酸素量が増加してじん性も劣化するため、
12〜20%にする必要がある。
さらにSiO2,TiO2についての組成条件として、
SiO2/TiO2=1.0〜1.55
とした理由はつぎのとおりである。
SiO2/TiO2の値は開先内でのスラグはく離性
とビード外観に関係する値でこの値が1.0より小
さい場合には、ビード幅の狭い余盛の高い凸ビー
ドになつて結果的にビードエツジ部のスラグはく
離性が悪くなる。
一方、1.55より大きい場合には、ビード外観は
良好となるもののスラグが完全にガラス化して開
先内でのはく離性が劣化するので、SiO2/TiO2
の値は1.0〜1.55にする必要がある。
Al2:2〜8%
Al2O3は、スラグの軟化温度に大きく影響する
と共にはく離性の向上にも有効に寄与する。
しかしながら2%未満では、スラグはく離性が
劣化し、一方8%を超えると融点が高くなりすぎ
て良好なビードが得られなくなることから、2〜
8%とした。
MnO:7〜15%
MnOは、ビード形状、溶接金属のじん性に関
係する成分である。その含有量が少ない場合には
ビードが凸状になりやすく、結果的にスラグのは
く離性を劣化させ、また溶接金属中のMnの歩留
りが悪くなつて焼入性が不足しじん性が劣化する
ので、少なくとも7%の添加が必要である。しか
しながら多すぎるとMnOの還元により酸素が増
加し、逆にじん性が劣化することから、15%以下
にする必要がある。
MgO:12〜20%
MgOは、塩基性成分であつて溶接金属の酸素
量を低減してじん性を向上させる作用があるが、
12%未満ではその効果が小さく、一方20%を超え
て添加するとスラグ軟化温度が高なりすぎ凸状ビ
ードになりやすいことから、12〜20%とした。
CaO:5〜17%
CaOは、フラツクス塩基度を高め溶接金属の酸
素量を低減してじん性を改善するのに有効に寄与
するが、5%未満ではその効果が期待できず、一
方17%を超えるビード表面に通称あばたと呼ばれ
るポツクマークが発生しやすくなり、かつフラツ
クス中の水素量も増加するため、5〜17%の範囲
にしなければならない。
CaF2:5〜15%
CaF2は、溶接金属の酸素量を低減する作用が
あり、少なすぎる場合にはその効果が期待できな
い。またCaF2はスラグ粘性を低下させる作用が
強く、添加しすぎるとスラグの流動性が大きくな
りすぎて開先内でのはく離性が劣化する。しかだ
つてこれらの理由から5〜15%の範囲に限定し
た。
NaOおよび/またはK2O:0.1〜2.0%
溶接においてアークを安定に保ことは良好なビ
ードを得るための基基本的条件であり、とくに狭
開先溶接のような通常の溶接よりも厳しい条件の
場合には必須の要件であるが、これらのアルカリ
酸化物は少量でサブマージアーク溶接時のアーク
安定性を大幅に向上させる作用がある。しかしな
がらこれらの配合量が0.1%に満たないとアーク
安定性を向上させる効果に乏しく、一方2.0%を
超えると、フラツクス中の水分量が増加し、結果
的に溶接金属拡散水素量の増加を招くため、これ
らの配合量は単独添加または複合添加いずれの場
合であつても0.1〜2.0%にする必要がある。
B2O3:1.0%以下
フラツクス中のB2O3は還元により溶接金属へ
のBの添加を可能とし、Ti−B系溶接金属とし
てじん性を向上させる点で有効である。しかしな
がら1.0%を超えて添加すると高温割れが発生し
易くなるため、1.0%以下で添加するものとした。
なお不可避的に混入するFeOやZrO2,BaOな
どについてはそれらの合計が5%以下であれば何
ら問題はない。
さらに発明者らの研究によれば、上記の成分範
囲を満足していてもフラツクス粒度を適正範囲に
調整しない場合にはアークを安定に保つて良好な
ビード形状を得ることができないことが判明し
た。
すなわち、粒度が粗い場合にはアーク中で発生
するガスの逸出と、アーク圧力のバランスが悪く
なつて不連続な吹き上げが起こり易く、良好なビ
ードが得られないため、全体の構成を細粒側に移
行させる必要があるが、逆に細粒が多すぎるとガ
スが抜けにくくなるため、この場合も良好なビー
ドが得られにくい。即ち単層溶接、多層溶接両者
において良好なビードを得るためには発生ガス逸
出がスムーズに行われ、アーク空洞圧力がほぼコ
ンスタントに保持される必要がある。
これを達成するためには、フラツクスの粒子径
が351μmより粗粒のものが全体の5%以下でか
つ、74μmより細粒のものが全体の5〜20%の範
囲にする必要がある。
(実施例)
実施例 1
第1表に示した組成に調整した種々のフラツク
スと、1.8Mn−0.5Mo系ワイヤとを組合せ、角
度:70゜、深さ:8mmのV溝加工を施した20mm厚
のJIS SM50B相当鋼板に、第2表に示す条件で
2電極サブマージアーク溶接を行い、ビード形
状、溶接欠陥などを調査した。
溶接作業性の評価結果および溶接金属の性能は
一括して、第3表に示した。
なお、2mmVノツチシヤルピー衝撃試験片は外
表面2mmの位置から採取した。
また溶接欠陥検査は目視によるアンダカツト検
査のほかX線透過検査による内部欠陥検査を実施
した。
さらに全フラツクスについて、JIS Z 3116に
基づく水素試験を実施し、その結果も第3表に併
記した。
(Industrial Application Field) This invention is a fusion type flux for submerged arc welding that can be applied from single layer welding of relatively thin steel plates to multilayer welding of thick steel plates, and in particular, in multilayer welding, it has excellent slag release properties within the groove. The present invention relates to a melt-type flux for submerged arc welding that provides a weld metal with good bead appearance and excellent mechanical performance. (Conventional technology) Automatic welding methods for steel plates include submerged arc welding, MIG welding, and CO 2 welding, but among these, submerged arc welding produces a large amount of welding and deep penetration. It is considered to be an excellent welding method in terms of efficiency and reliability of the joints obtained, and is particularly widely used for welding thick steel plates. By the way, there are two types of flux for submerged arc welding: a fired type and a melted type.The former is made by granulating and firing raw raw materials using a binder such as water glass, and then adding a gas generating source to the flux.
Although it has advantages such as reducing the amount of diffusible hydrogen by reducing the hydrogen partial pressure in the arc and allowing alloying elements to be added from flux, it also has the disadvantages of easy moisture absorption and difficulty in multi-electrode high-speed welding. There are drawbacks. On the other hand, melting type flux melts the raw material and then
It is manufactured by crushing a glass-like solidified product, but since it is usually glass-like, it has the advantage of being difficult to absorb moisture and being suitable for multi-electrode high-speed welding. These are used differently depending on the purpose so that the characteristics of each can be utilized. For example UOE
When welding speed greatly affects the production capacity of the entire factory, such as for pipes, it is necessary to adopt a multi-electrode high-speed welding method, and generally a multi-electrode, double-sided, single-layer welding method using molten flux is applied. has been done. In this case, the characteristics required for the flux are:
Good beads without defects can be obtained even at high speeds, and the mechanical performance of the weld metal is excellent. However, when multi-layer welding is required, such as when welding thick steel plates, the time required for slag removal has a greater effect on the overall efficiency than the actual welding time, resulting in poor slag removal. Flux requires a great deal of time and effort to remove, which is undesirable. As mentioned above, when longitudinal seam welding such as UOE pipe is carried out in a systemized factory, the welding speed has a large effect on productivity, but the shapes of steel frames, bridges, etc. vary, and it is not possible to weld long seams that are close to single parts. Efficiency will be improved if the slag can be reliably removed, the bead shape is good, and welding can be performed without defects. For example, in multi-layer welding, if a flux with poor releasability is used, not only will it take a lot of time and effort to remove the slag, but if the removal is incomplete, the slag left behind will cause poor penetration and slag entrainment. There is a problem in that welding defects such as these are likely to occur. The slag releasability is particularly susceptible to deterioration when the groove angle is narrow, and in the case of a normal X-groove, the slag releasability of the first layer weld, which is the tightest, often becomes a problem. In other words, in the conventional SiO 2 -MnO and SiO 2 -MnO-CaO fluxes commonly used for multilayer welding, the groove angle has been widened to 60° or more in order to improve slag removal within the groove. Moreover, in order to prevent deterioration of the bead shape, slow speed and low heat input welding is often used, which cannot be said to be very efficient. As a method to improve slag flaking, SiO 2
- A method of adding a small amount of PbO to MnO-based flux is proposed in JP-A-53-133543;
This method has the problem of worrying about the effects of Pb on the human body. On the other hand, several proposals have already been made for fluxes that improve slag releasability and can be applied to narrow gap welding. For example, JP-A No. 55-10356,
Publications No. 55-10357 and No. 55-10358, etc., which define the component range of flux,
Although it is designed to enable narrow gap welding, since SiO 2 is reduced and a large amount of Al 2 O 3 is added, there is a problem that the flux melting point is high and it is difficult to form a bead width. When applied to single-layer or multi-layer butt welding, the width is narrower than that of a flux with a large amount of SiO 2 , and the resulting bead tends to have a high bead height, which is unfavorable in terms of appearance. Here, the following items can be considered as requirements for improving slag removability. (1) There is a large difference between the volumetric shrinkage of the slag and the volumetric shrinkage of the weld metal. (2) The adhesion force between slag and weld metal is small. (3) The cross-sectional shape of the bead is concave and does not mechanically restrain the slag. Regarding (1), it is generally advantageous for the slag to have a larger thermal expansion coefficient, and for this reason it is desirable that the slag separation and solidification temperature be high, but if it is too high, it will be difficult to form a bead width. , must be selected taking this point into consideration. Regarding (2), it is closely related to the interfacial tension between the slag and the weld metal, and as the interfacial energy increases, the adhesion force decreases. Regarding (3), in the case of a convex bead, an undercut occurs at the edge, which mechanically restrains the slag and impedes peelability, so the bead shape must be flat or concave. Since welding conditions are also related to this bead shape, it is of course important to select appropriate conditions. Furthermore, in addition to good slag releasability, the weld metal must have good toughness, and the amount of diffusible hydrogen in the weld metal must be small to prevent cold cracking. . (Problems to be Solved by the Invention) In submerged arc welding, this invention not only provides a good wide bead appearance during single-layer welding, but also provides good slag removability even during multi-layer welding, and also improves the appearance and appearance. The purpose of this study is to propose a molten type flux that also improves the mechanical performance of weld metal. (Means for Solving the Problems) First, the background to the elucidation of this invention will be explained. The inventors melted fluxes with various compositions and investigated the appearance and shape of the bead during single-layer welding, as well as the slag releasability, bead shape, and weld metal properties during multilayer welding within a groove with a relatively small angle. Toughness and other aspects were comprehensively considered. As a result, when the flux contains relatively large amounts of SiO 2 , TiO 2 , and MgO, and the SiO 2 satisfies a certain relationship, the bead width is wide and the flux melts within the groove without making the melting point that high. It has been found that the slag releasability of this material is extremely good, and that the cross-sectional shape of the bead is also flat or concave. At that time, the slag was almost glassy, and a very small amount of TiO 2 crystalline material was observed by microscopic observation and X-ray observation. It is possible that the amount of shrinkage is increased. From this point of view, it is thought that stable slag releasability can be obtained by making the entire slag crystalline, but this requires increasing TiO 2 and Al 2 O 3 , which results in a decrease in the slag melting point. It was also found that it is better not to increase these values unnecessarily, since this increases the bead width, reduces the bead width, and increases the amount of hydrogen in the flux. In addition, SiO 2 must be added in a certain amount or more in order to widen the bead width, and from the standpoint of weld metal toughness, MgO must be added a little more.
It was also found that it was necessary to add more than a certain amount of CaO and CaF 2 to reduce the amount of oxygen in the weld metal. In this way, the prototype flux was able to obtain a good bead during single-layer welding, and had good slag removal properties within the groove during multi-layer welding, but further investigation in relation to the flux particle size showed that It has also been found that beads with better shapes can be obtained with fluxes having a certain particle size condition. This invention is based on the above knowledge. That is, in this invention, SiO2 : 20 to 30 wt% (hereinafter simply expressed in %) TiO2 : 13 to 20%, SiO2 / TiO2 = 1.0 to 1.55, Al2O3 : 2 to 8% MnO: 7 to 15% MgO: 12 to 20% CaO: 5 to 17% CaF 2 : 5 to 15% and the total of one or two selected from Na 2 O and K 2 O: 0.1 to 2.0%. The flux has a particle size of
Less than 5% of the total particles are coarser than 351μm, 74μm
This is a molten flux for submerged arc welding in which finer particles account for 5 to 20% of the total. Moreover, this invention has SiO2 : 20-30% TiO2 : 13-20%, and SiO2 / TiO2 =1.0-1.55, Al2O3 : 2-8% MnO: 7-15% MgO : 12- 20% CaO: 5-17% B 2 O 3 : 1.0% or less CaF 2 : 5-15% and one or two selected from Na 2 O and K 2 O Total composition: 0.1-2.0% It is a flux with a particle size of
Less than 5% of the total particles are coarser than 351μm, 74μm
This is a molten flux for submerged arc welding in which finer particles account for 5 to 20% of the total. (Function) First, in this invention, the reason why the component composition is limited to the above range will be explained. SiO 2 :20-30% SiO 2 is an important component of flux and has a great effect on bead appearance, weld metal toughness, etc. If the blending amount is less than 20%, the bead width will be difficult to obtain and the bead will be unfavorable in appearance;
%, the amount of oxygen in the weld metal will increase and the toughness will deteriorate, so it is necessary to set it to 20 to 30%. TiO 2 : 13-20% TiO 2 has a large effect on the slag releasability within the groove; if it is less than 13%, the slag tends to stick to the bead, while if it exceeds 20%, the slag becomes crystalline all over. The bead width becomes difficult to obtain, and the amount of oxygen in the weld metal increases and the toughness deteriorates.
It should be 12-20%. Furthermore, the reason why the composition conditions for SiO 2 and TiO 2 were set to SiO 2 /TiO 2 =1.0 to 1.55 is as follows. The value of SiO 2 /TiO 2 is a value related to the slag separation property within the groove and the appearance of the bead. If this value is less than 1.0, the bead will become a convex bead with a narrow bead width and a high reinforcement. Slag removability at the bead edge becomes poor. On the other hand, if it is larger than 1.55, the bead appearance will be good, but the slag will be completely vitrified and the releasability within the groove will deteriorate, so SiO 2 /TiO 2
The value of must be between 1.0 and 1.55. Al2 : 2 to 8% Al2O3 has a large effect on the softening temperature of the slag, and also effectively contributes to improving the releasability. However, if it is less than 2%, the slag releasability deteriorates, while if it exceeds 8%, the melting point becomes too high and good beads cannot be obtained.
It was set at 8%. MnO: 7 to 15% MnO is a component related to the bead shape and the toughness of the weld metal. If the content is low, the bead tends to become convex, resulting in poor slag releasability, and the yield of Mn in the weld metal decreases, resulting in insufficient hardenability and deterioration of toughness. Therefore, it is necessary to add at least 7%. However, if it is too large, oxygen will increase due to the reduction of MnO and the toughness will deteriorate, so it is necessary to keep it below 15%. MgO: 12-20% MgO is a basic component that reduces the amount of oxygen in the weld metal and improves its toughness.
If it is less than 12%, the effect will be small, while if it is added in excess of 20%, the slag softening temperature will become too high and convex beads will easily form. Therefore, the content was set at 12 to 20%. CaO: 5-17% CaO increases flux basicity and reduces the amount of oxygen in the weld metal, effectively contributing to improving toughness, but if it is less than 5%, no effect can be expected; It must be within the range of 5 to 17%, since pockmarks, commonly called pockmarks, are likely to occur on the bead surface in excess of 5%, and the amount of hydrogen in the flux also increases. CaF2 : 5 to 15% CaF2 has the effect of reducing the amount of oxygen in the weld metal, and if it is too small, the effect cannot be expected. Furthermore, CaF 2 has a strong effect of lowering slag viscosity, and if it is added too much, the fluidity of the slag becomes too large and the releasability within the groove deteriorates. However, for these reasons, it was limited to a range of 5 to 15%. NaO and/or K 2 O: 0.1 to 2.0% Keeping the arc stable during welding is a basic condition for obtaining a good bead, especially conditions that are stricter than normal welding such as narrow gap welding. These alkali oxides have the effect of greatly improving arc stability during submerged arc welding, even in small amounts, which is an essential requirement in the case of submerged arc welding. However, if the blending amount is less than 0.1%, it will have little effect on improving arc stability, while if it exceeds 2.0%, the moisture content in the flux will increase, resulting in an increase in the amount of hydrogen diffused in the weld metal. Therefore, the blending amount of these components needs to be 0.1 to 2.0%, whether added alone or in combination. B 2 O 3 : 1.0% or less B 2 O 3 in the flux enables the addition of B to the weld metal through reduction, and is effective in improving the toughness of the Ti-B weld metal. However, if added in excess of 1.0%, hot cracking is likely to occur, so it was decided to add at 1.0% or less. Note that there is no problem with regard to FeO, ZrO 2 , BaO, etc., which are inevitably mixed in, as long as their total content is 5% or less. Furthermore, according to the inventors' research, it was found that even if the above component range was satisfied, it was not possible to maintain a stable arc and obtain a good bead shape unless the flux particle size was adjusted to an appropriate range. . In other words, if the grain size is coarse, the balance between the escape of the gas generated in the arc and the arc pressure will be poor, causing discontinuous blow-up and making it difficult to obtain a good bead. On the other hand, if there are too many fine particles, it will be difficult for gas to escape, so it will be difficult to obtain a good bead in this case as well. That is, in order to obtain a good bead in both single-layer welding and multi-layer welding, it is necessary that the generated gas escape smoothly and that the arc cavity pressure be maintained almost constantly. In order to achieve this, it is necessary that the flux particles coarser than 351 .mu.m account for 5% or less of the total, and the flux particles finer than 74 .mu.m account for 5 to 20% of the total. (Example) Example 1 Various fluxes adjusted to the compositions shown in Table 1 were combined with 1.8Mn-0.5Mo wire to form a 20mm V-groove with an angle of 70° and a depth of 8mm. Two-electrode submerged arc welding was performed on a JIS SM50B thick steel plate under the conditions shown in Table 2, and the bead shape, welding defects, etc. were investigated. The evaluation results of welding workability and the performance of the weld metal are shown in Table 3. Note that a 2 mm V-notched mechanical impact test piece was taken from a position 2 mm from the outer surface. In addition, welding defect inspection included visual undercut inspection and internal defect inspection using X-ray transmission inspection. Furthermore, all fluxes were subjected to a hydrogen test based on JIS Z 3116, and the results are also listed in Table 3.
【表】【table】
【表】
* アンダラインはこの発明の適正範囲からはずれて
いることを示す。
[Table] * Underlined values indicate that the values are outside the appropriate range of this invention.
【表】【table】
【表】
第3表に示したとおり、この発明に従うフラツ
クスは、スラグはく離性、ビード形状が良好で欠
陥が無く、溶接金属のじん性も優れており、さら
には拡散性水素量も2c.c./100gD.M以下と少な
く、水素割れの危険性も小さかつた。
一方、比較フラツクスにおいては、V溝1層溶
接であるため化学組成、粒度構成が発明範囲外で
あつてもスラグはく離性はとくに問題なかつた
が、化学組成や、粒度構成等の関係で多少の問題
があるものがあつた。
すなわちB1ではとくに大きな問題は無かつた
(後述するように多層溶接では問題がある)が、
B2ではSiO2量が多いため、SiO2の還元による溶
接金属中の酸素量増加が原因で溶接金属じん性が
低い。
B3は、粒度が粗目であるため、ビード形状が
凸ぎみでアンダカツトが発生した。
B4は、B1同様V溝1層溶接では作業性の上で
とくに大きな問題は無かつたが、MnOが多く、
MgOが少ないので溶接金属のじん性が低かつた。
B5は、粒度がやや粗く多少凸状ビードとなり
易く、またCaOが多いためアバタが発生した。
B6は、細粒が多すぎて溶接時に呼き上げが起
り、結果的にビードが蛇行する結果となつた。ま
たビード幅も狭い傾向が認められた。
実施例 2
第1表に示したフラツクスを用い、X開先を加
工した板厚38mmのSM50Bに1〜2電極サブマー
ジアーク多層溶接を実施した。ワイヤは実施例1
と同様1.80Mn−0.5Mo系のものを用いた。
第1図は、X開先の形状を示したもので、この
場合第2図の如く内面側は1パス仕上げとし、外
面側は1層1〜2パス積層法で5パス溶接とし
た。初層のみ高温割れ防止1電極溶接とした。第
4表は、このときの溶接条件を示したものであ
る。
検査項目として外面側多層溶接時のスラグはく
離性、ビード形状を調査し、さらに完全に積層し
た後にX線透過検査により欠陥を調査した結果を
第5表に示す。[Table] As shown in Table 3, the flux according to the present invention has good slag releasability, good bead shape, no defects, and excellent weld metal toughness, and furthermore, the amount of diffusible hydrogen is 2 c.c. ./100gD.M or less, and the risk of hydrogen cracking was also small. On the other hand, in the comparative flux, there was no particular problem in slag releasability even though the chemical composition and grain size composition were outside the scope of the invention because it was a single layer welding with a V groove. There was something problematic. In other words, there were no major problems with B1 (there are problems with multi-layer welding, as described later), but
In B2, the amount of SiO 2 is large, so the weld metal toughness is low due to the increase in the amount of oxygen in the weld metal due to the reduction of SiO 2 . Since B3 had a coarse grain size, the bead shape was too convex and undercuts occurred. Like B1, B4 did not have any major problems in terms of workability when welding a single layer of V-groove, but it contained a lot of MnO.
Since there is little MgO, the toughness of the weld metal is low. B5 had a slightly coarse particle size and tended to form somewhat convex beads, and also had a large amount of CaO, so avatars occurred. With B6, there were too many fine grains, which caused rise-up during welding, resulting in a meandering bead. It was also observed that the bead width tended to be narrower. Example 2 Using the flux shown in Table 1, 1- to 2-electrode submerged arc multilayer welding was performed on a 38 mm thick SM50B plate with an X groove. The wire is Example 1
Similar to 1.80Mn−0.5Mo, a 1.80Mn−0.5Mo system was used. FIG. 1 shows the shape of the X groove. In this case, as shown in FIG. 2, the inner surface was finished in one pass, and the outer surface was welded in five passes using a one-layer, one- to two-pass lamination method. Only the first layer was welded with one electrode to prevent hot cracking. Table 4 shows the welding conditions at this time. Table 5 shows the results of inspecting slag peelability and bead shape during multi-layer welding on the outer surface as inspection items, and inspecting for defects by X-ray inspection after complete lamination.
【表】【table】
【表】【table】
【表】
第5表から明らかなように、この発明フラツク
スは内面の一層溶接はもちろんのこと、多層溶接
となる外面溶接においてもスラグはく離性、ビー
ド形状ともに良好であつて、X線透過検査によつ
てもスラグ巻込みは発生しておらず、内外面ビー
ドのラツプも十分であるため溶接能率は非常に良
かつた。
一方、比較フラツクスではV溝一層溶接となる
内面溶接ではあまり大きな問題は無く、実施例1
とほぼ同様の結果であつたが、多層溶接となる外
面側の溶接では開先内スラグはく離性が悪かつた
り、あるいはビード形状が悪かつたりなどの問題
点があつた。比較フラツクス全ての共通していた
のはスラグはく離性が悪いことであり、ビードに
こびり付いたスラグをピツチングハンマーやタガ
ネで除去するのに多大の時間を要した。
すなわちB1では、フラツクス粒度構成は狙い
通りのものであつたが、SiO2/TiO2値がこの発
明の適正範囲から逸脱しているため、ビード形状
は良好であつてもスラグがビード表面にこびり付
きはく離が悪かつた。
B2では、SiO2が多いだけでなくSiO2/TiO2も
大きいためB1同様開先内スラグはく離性が不良
であつた。ただしビード形状の劣化はとくに認め
られなかつた。
B3ではSiO2/TiO2値が適正範囲で大きいため
開先内でのスラグはく離性が不良であり、粒度構
成も351μmより粗粒の粒子が19.4%と多く、
74μmより細粒のものが4.4%と少ないためビード
形状も凸となり、次パスでの溶接狙い位置を決定
しにくかつた。
B4は、B1同様、ビード形状は良好であつても
スラグはく離性が悪かつた。
B5,B6も化学組成がこの発明の適正範囲外で
あるため開先内スラグはく離性が悪く、粉体特性
もはずれているため、凸ぎみやアンダカツトぎみ
のビードとなつている。
実施例 3
実施例1で使用したフラツクスA3およびA6に
B2O3を0.3%添加したフラツクス2種類を用い、
また実施例1と同様の溶接条件、鋼板ワイヤを用
いてV溝1層溶接を行つた。
その結果は第6表に示したとおりで、溶接金属
じん性はB2O3の存在しない場合いに比べてさら
に向上している。[Table] As is clear from Table 5, the flux of the present invention has good slag releasability and bead shape not only for single-layer inner welding but also for multi-layer outer welding, and is suitable for X-ray inspection. Even after welding, no slag entrainment occurred, and the welding efficiency was very good because the lap between the inner and outer beads was sufficient. On the other hand, with the comparative flux, there was no major problem in internal welding, which is one-layer V-groove welding, and Example 1
The results were almost the same, but there were problems such as poor slag removal within the groove and poor bead shape when welding on the outer surface, which is multilayer welding. All the comparative fluxes had in common that they had poor slag removability, and it took a lot of time to remove the slag stuck to the beads with a pitting hammer or chisel. In other words, in B1, the flux particle size composition was as desired, but the SiO 2 /TiO 2 value was outside the appropriate range of this invention, so slag stuck to the bead surface even if the bead shape was good. Peeling was poor. B2 had not only a large amount of SiO 2 but also a large SiO 2 /TiO 2 ratio, and as with B1, the in-groove slag releasability was poor. However, no particular deterioration of the bead shape was observed. In B3, the SiO 2 /TiO 2 value is large within the appropriate range, so the slag releasability within the groove is poor, and the particle size composition is 19.4%, which is coarser than 351 μm.
Since the amount of particles finer than 74μm was 4.4%, the bead shape also became convex, making it difficult to determine the target welding position for the next pass. Like B1, B4 had poor slag releasability even though the bead shape was good. Since the chemical compositions of B5 and B6 are outside the appropriate range of the present invention, the slag releasability within the groove is poor, and the powder properties are also off, resulting in beads that are convex or undercut. Example 3 Fluxes A3 and A6 used in Example 1
Using two types of fluxes containing 0.3% B 2 O 3 ,
In addition, single-layer V-groove welding was performed under the same welding conditions as in Example 1 and using steel plate wire. The results are shown in Table 6, and the weld metal toughness was further improved compared to the case where B 2 O 3 was not present.
【表】
(発明の効果)
かくしてこの発明フラツクスによれば、1層溶
接で良好なビードが得られるのはいうまでもな
く、比較的角度の小さい開先内での多層溶接にお
いても良好なスラグはく離性、ビード形状、外観
が得られ、しかも得られる溶接金属の性能にも優
れているため、従来法に比較して溶接工数の大幅
な短縮が可能となる。
なお、この発明フラツクスは、大入熱多層溶接
にももちろん適用できるものであり、その工業的
価値は極めて大きい。[Table] (Effects of the Invention) Thus, according to the flux of the present invention, it goes without saying that a good bead can be obtained in single layer welding, but also a good slag can be obtained in multilayer welding within a groove with a relatively small angle. Since the releasability, bead shape, and appearance are excellent, and the performance of the resulting weld metal is also excellent, it is possible to significantly reduce the number of welding steps compared to conventional methods. Incidentally, the flux of the present invention can of course be applied to high heat input multilayer welding, and its industrial value is extremely large.
第1図は、実施例2で用いたX開先形状を示し
た図、第2図は、実施例2における積層要領の説
明図である。
FIG. 1 is a diagram showing the X groove shape used in Example 2, and FIG. 2 is an explanatory diagram of the lamination procedure in Example 2.
Claims (1)
351μmより粗粒のものが全体の5wt%以下、
74μmより細粒のものが全体の5〜20wt%を占め
ることを特徴とするサブマージアーク溶接用溶融
型フラツクス。 2 SiO2:20〜30wt% TiO2:13〜20wt%でかつ SiO2/TiO2=1.0〜1.55、 Al2O3:2〜8wt% MnO:7〜15wt% MgO:12〜20wt% CaO:5〜17wt% B2O3:1.0wt%以下 CaF2:5〜15wt%および Na2O,K2Oのうちから選んだ一種又は 二種合計:0.1〜2.0wt% の組成になるフラツクスであつて、粒子径が
351μmより粗粒のものが全体の5wt%以下、
74μmより細粒のものが全体の5〜20wt%を占め
ることを特徴とするサブマージアーク溶接用溶融
型フラツクス。[Claims] 1 SiO 2 : 20 to 30 wt% TiO 2 : 13 to 20 wt%, and SiO 2 /TiO 2 = 1.0 to 1.55, Al 2 O 3 : 2 to 8 wt% MnO: 7 to 15 wt% MgO: A flux having a composition of 12 to 20 wt% CaO: 5 to 17 wt% CaF 2 : 5 to 15 wt% and one or two selected from Na 2 O and K 2 O: 0.1 to 2.0 wt%, The particle size is
Less than 5wt% of the total particles are coarser than 351μm,
A molten flux for submerged arc welding, characterized in that particles finer than 74 μm account for 5 to 20 wt% of the total flux. 2 SiO2 : 20-30wt% TiO2 : 13-20wt% and SiO2 / TiO2 =1.0-1.55, Al2O3 : 2-8wt % MnO: 7-15wt% MgO: 12-20wt% CaO: A flux with a composition of 5-17wt% B 2 O 3 : 1.0wt% or less CaF 2 : 5-15wt% and one or two selected from Na 2 O, K 2 O Total: 0.1-2.0wt% If the particle size is
Less than 5wt% of the total particles are coarser than 351μm,
A molten flux for submerged arc welding, characterized in that particles finer than 74 μm account for 5 to 20 wt% of the total flux.
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP29508787A JPH01138097A (en) | 1987-11-25 | 1987-11-25 | Melting flux for submerged arc welding |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP29508787A JPH01138097A (en) | 1987-11-25 | 1987-11-25 | Melting flux for submerged arc welding |
Publications (2)
Publication Number | Publication Date |
---|---|
JPH01138097A JPH01138097A (en) | 1989-05-30 |
JPH0451279B2 true JPH0451279B2 (en) | 1992-08-18 |
Family
ID=17816137
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
JP29508787A Granted JPH01138097A (en) | 1987-11-25 | 1987-11-25 | Melting flux for submerged arc welding |
Country Status (1)
Country | Link |
---|---|
JP (1) | JPH01138097A (en) |
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
CN103358054A (en) * | 2012-04-10 | 2013-10-23 | 机械科学研究院哈尔滨焊接研究所 | Coating for removing slag on laser cutting reverse side of thick steel plate |
-
1987
- 1987-11-25 JP JP29508787A patent/JPH01138097A/en active Granted
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
CN103358054A (en) * | 2012-04-10 | 2013-10-23 | 机械科学研究院哈尔滨焊接研究所 | Coating for removing slag on laser cutting reverse side of thick steel plate |
Also Published As
Publication number | Publication date |
---|---|
JPH01138097A (en) | 1989-05-30 |
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