JPS6260462B2 - - Google Patents
Info
- Publication number
- JPS6260462B2 JPS6260462B2 JP53020300A JP2030078A JPS6260462B2 JP S6260462 B2 JPS6260462 B2 JP S6260462B2 JP 53020300 A JP53020300 A JP 53020300A JP 2030078 A JP2030078 A JP 2030078A JP S6260462 B2 JPS6260462 B2 JP S6260462B2
- Authority
- JP
- Japan
- Prior art keywords
- electric resistance
- welding
- less
- steel
- resistance welded
- 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
- 229910000831 Steel Inorganic materials 0.000 claims description 32
- 239000010959 steel Substances 0.000 claims description 32
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims description 19
- 239000001301 oxygen Substances 0.000 claims description 19
- 229910052760 oxygen Inorganic materials 0.000 claims description 19
- NINIDFKCEFEMDL-UHFFFAOYSA-N Sulfur Chemical compound [S] NINIDFKCEFEMDL-UHFFFAOYSA-N 0.000 claims description 16
- 229910052717 sulfur Inorganic materials 0.000 claims description 16
- 239000011593 sulfur Substances 0.000 claims description 16
- 239000000126 substance Substances 0.000 claims description 9
- 239000000203 mixture Substances 0.000 claims description 5
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims description 4
- 238000005275 alloying Methods 0.000 claims description 4
- 239000012535 impurity Substances 0.000 claims description 3
- 229910052742 iron Inorganic materials 0.000 claims description 2
- 238000003466 welding Methods 0.000 description 45
- 229910052751 metal Inorganic materials 0.000 description 24
- 239000002184 metal Substances 0.000 description 24
- 238000000034 method Methods 0.000 description 21
- 238000012360 testing method Methods 0.000 description 9
- 230000007547 defect Effects 0.000 description 8
- 238000010438 heat treatment Methods 0.000 description 8
- 230000000694 effects Effects 0.000 description 6
- 238000010586 diagram Methods 0.000 description 5
- 238000004519 manufacturing process Methods 0.000 description 5
- 238000009863 impact test Methods 0.000 description 4
- 239000000463 material Substances 0.000 description 4
- 229910052782 aluminium Inorganic materials 0.000 description 3
- 229910052804 chromium Inorganic materials 0.000 description 3
- 229910052748 manganese Inorganic materials 0.000 description 3
- 238000005259 measurement Methods 0.000 description 3
- 230000008018 melting Effects 0.000 description 3
- 238000002844 melting Methods 0.000 description 3
- 229910052758 niobium Inorganic materials 0.000 description 3
- 238000005096 rolling process Methods 0.000 description 3
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 description 2
- 230000007797 corrosion Effects 0.000 description 2
- 238000005260 corrosion Methods 0.000 description 2
- 230000007423 decrease Effects 0.000 description 2
- 229910052750 molybdenum Inorganic materials 0.000 description 2
- 229910052759 nickel Inorganic materials 0.000 description 2
- 238000007670 refining Methods 0.000 description 2
- 230000000630 rising effect Effects 0.000 description 2
- 238000009958 sewing Methods 0.000 description 2
- 229910052719 titanium Inorganic materials 0.000 description 2
- 230000007704 transition Effects 0.000 description 2
- 229910052720 vanadium Inorganic materials 0.000 description 2
- RBTBFTRPCNLSDE-UHFFFAOYSA-N 3,7-bis(dimethylamino)phenothiazin-5-ium Chemical compound C1=CC(N(C)C)=CC2=[S+]C3=CC(N(C)C)=CC=C3N=C21 RBTBFTRPCNLSDE-UHFFFAOYSA-N 0.000 description 1
- 238000010521 absorption reaction Methods 0.000 description 1
- 239000008186 active pharmaceutical agent Substances 0.000 description 1
- 229910052786 argon Inorganic materials 0.000 description 1
- 239000010953 base metal Substances 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 238000002485 combustion reaction Methods 0.000 description 1
- 239000000470 constituent Substances 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 229910052802 copper Inorganic materials 0.000 description 1
- 230000002950 deficient Effects 0.000 description 1
- 230000001066 destructive effect Effects 0.000 description 1
- 230000006866 deterioration Effects 0.000 description 1
- 238000009826 distribution Methods 0.000 description 1
- 230000005496 eutectics Effects 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 239000007789 gas Substances 0.000 description 1
- 238000002347 injection Methods 0.000 description 1
- 239000007924 injection Substances 0.000 description 1
- 229960000907 methylthioninium chloride Drugs 0.000 description 1
- 238000010606 normalization Methods 0.000 description 1
- 238000012545 processing Methods 0.000 description 1
- 229910052761 rare earth metal Inorganic materials 0.000 description 1
- 238000010008 shearing Methods 0.000 description 1
- 150000004760 silicates Chemical class 0.000 description 1
- 238000007711 solidification Methods 0.000 description 1
- 230000008023 solidification Effects 0.000 description 1
- 238000005728 strengthening Methods 0.000 description 1
- 230000002195 synergetic effect Effects 0.000 description 1
- 238000010998 test method Methods 0.000 description 1
Landscapes
- Heat Treatment Of Articles (AREA)
Description
本発明は電縫衝合部靭性の優れた電縫鋼管に関
するものである。
周知の如く、電縫管の製造方法は帯板を管状に
成型し、高周波電流によつて管エツジを加熱、溶
融し、スクイズロールにより加圧圧接して溶接
し、電縫部高靭性を要求される場合には通常のシ
ームノルマライズ（後熱処理）を施して製管され
ている。
第１図はこの方法により製造された電縫管の電
縫溶接部近傍の横断面を示す図であるが、電縫衝
合部１に冷接、ペネトレーターと呼ばれる電縫管
特有の溶接欠陥の発生を伴うことがあり、実際に
パイプとして使用した場合、該欠陥を起点として
電縫衝合部に沿つて脆性破壊が発生することがあ
つた。
また、電縫衝合部１と熱影響部２，２′からな
る電縫溶接部とりわけ電縫衝合部は、高温で加圧
圧接されるため母材部３，３′に比べ、著しく靭
性が劣化し、例えばシヤルピー衝撃値が低く、要
求された仕様を満たすことが困難であるばかり
か、更に、不安定延性破壊を生じ易いと言う危険
性もある。尚、電縫溶接においては突合せ部のア
プセツトの際電縫溶接部近傍の金属がメタルフロ
ーを起し、その流れの方向は電縫衝合部に向つて
立上つている。
第１図にはこの状況を模式的に示してあり、４
は熱影響部片側のメタルフローでθをメタルフロ
ー立上角度と言う。このメタルフロー立上り角度
はアプセツト量によつて変わることは言うまでも
ない。
このような電縫衝合部（以下電縫部と称する）
の破壊的見地からみて、靭性が悪いと言う問題点
に対し、従来、前述の如く、電縫部を後熱処理し
て靭性改善を意図した方法に例えば特開昭50−
86442号で提案された方法がある。しかし、この
方法は第２図に示す如くエネルギー遷移温度或は
破面遷移温度を低温側に移行する効果あるもの
の、衝撃値そのものを高くするまでには至らな
い。更に後熱処理の最高加熱温度、管厚方向の温
度分布不均一等によつて衝撃値のバラツキが多く
なる場合があることを本発明者等は確認してい
る。
また、熱影響部のメタルフロー立上り角を小さ
くして、高い衝撃値をもつ電縫部を得ることを意
図した例えば特開昭53−1673号で提案された方法
があるが、本発明者等の実験によればメタルフロ
ー立上りが小さくなるような例えばアプセツト量
の少い溶接を行うと、第３図に示す如く電縫衝合
部に冷接、ペネトレーターの溶接欠陥が多発する
傾向にあり、前述した脆性破壊の起点となり易
く、却つて安全性に対する信頼性を損なう結果と
なり、更に超音波試験で不良と判定される場合が
多くなつて著しく生産性を低下させることにな
る。
一方、鋼板の化学組成に関し、鋼中の硫黄量を
低減すると、とくに圧延と直角方向から採取した
シヤルピー試片でのシエルフエネルギーが高くな
ることが知られているが、電縫部の如くその製造
工程上、加熱−溶融−加圧圧接を受ける部分にお
いては、その効果は定性的にも定量的にも十分検
討されていない。
更に、付言するならば、電縫部衝撃値と素材化
学成分との関係については全く不明であり、他の
靭性改善法も含めて、いわゆる高靭性電縫溶接部
をもつ電縫管を安定供給することは従来からでき
なかつたのである。
本発明は、このように従来から未解決の問題点
に鑑み、これを解決すべくなされてものである。
即ち、本発明者等は、これまで鋼中の酸素量が
少いと、MnSが凝固時に型（粒界共晶型）、
型（角型）となり易く、圧延乃至圧接後長く伸長
し、Ａ系介在物量を多くすると考えられていたの
に対し加熱、溶融、加圧圧接される電縫部におい
ては、鋼中の酸素量が低くても、Ａ系介在物が実
質的に多くならないと言う全く新しい知見のもと
に、むしろ低酸素量による衝撃値のバラツキを少
くする効果を相乗せしめ、これによつて相乗効果
を発揮させることが可能であると言う極めて新規
な知見を得て、電縫鋼管の生産性を損なうことな
く、品質、安全性、信頼性を向上したものであ
る。
本発明の要旨とするところは、化学組成が主に
鉄とその他の通常の合金元素及び不可避的不純物
からなる帯鋼を素材として製造された電縫鋼管に
あつて、該不純物元素のうち、硫黄0.002％以
下、酸素0.004％以下であり、かつ、電縫溶接部
におけるJISG 0555により測定されるＡ系非金属
介在物が0.009％以下であることを特徴とする電
縫衝合部靭性の優れた電縫鋼管にあり、シームノ
ルマ後電縫部２mmＶノツチシヤルピー試験の衝撃
値が試験温度−30℃において2.4Kg・ｍ／cm2以上
を安定して確保できるものである。
以下に、本発明を詳細に説明する。
先ず、本発明に言う通常の合金元素とは、Ｃ、
Si、Mnとさらには必要に応じてNi、Cr、Mo、
Cuと少量のAl、Nb、Ｖ、Tiなどを指し、その範
囲としてはＣ：0.01〜0.29％、Si：0.01〜0.60
％、Mn：0.3〜2.5％、更には必要に応じてNi：
３％以下、Cr：2.5％以下、Mo：0.7％以下、
Cu：0.5％以下とAl：0.1％以下、Nb：0.08％以
下、Ｖ：0.3％以下、Ti：0.05％以下の１種以上
を含有するもので、特にAPI5A、5AC、5AX及び
5L、5LX規格の油井管及びラインパイプ等に用
いられる電縫鋼管の成分元素範囲を含むものであ
る。
次に本発明において、硫黄量0.002％以下、酸
素量0.004％以下としたのは次の理由によるもの
である。
即ち、本発明者等は第１表に示す如きＣ：0.08
〜0.128％、Si：0.18〜0.40％、Mn：1.10〜1.35
％、Al：0.027〜0.05％、Nb：0.016〜0.035％、
Ｖ：0.01〜0.04％、Cr：0.006〜0.015％、Cu：
0.006〜0.01％を基本成分とするAPI5LX−X65の
強度（耐力45.6Kg／mm2以上、引張り強さ54.1Kg／
mm2以上）をもつ電縫管用帯鋼について、硫黄及び
酸素レベルを種々かえ、高周波電縫溶接装置を用
い、特開昭52−111851号等で公知の溶接現象を、
第２種の溶接現象とし、アプセツト量を３mmと一
定条件にして溶接を行つた。
The present invention relates to an electric resistance welded steel pipe with excellent toughness at the electric resistance welded abutment. As is well known, the manufacturing method for electric resistance welded tubes involves forming a strip into a tube shape, heating and melting the tube edge using a high-frequency current, and welding by pressure welding with a squeeze roll, which requires high toughness of the electric resistance welded part. In some cases, pipes are made by applying normal seam normalization (post-heat treatment). Fig. 1 is a cross-sectional view of the vicinity of the ERW welded part of the ERW pipe manufactured by this method, and shows that the ERW abutment part 1 has cold welding and a welding defect called a penetrator, which is unique to ERW pipes. When actually used as a pipe, brittle fracture could occur along the electric resistance welded abutting portion starting from the defect. In addition, the electric resistance welding part, especially the electric resistance welding part, which consists of the electric resistance sewing abutment part 1 and the heat affected zones 2 and 2', is significantly tougher than the base material parts 3 and 3' because it is pressure welded at high temperature. Not only is it difficult to meet the required specifications due to deterioration of the steel, for example, the shear value is low, but there is also a risk that unstable ductile fracture is likely to occur. In electric resistance welding, when an abutting portion is upset, metal near the electric resistance welding portion causes a metal flow, and the direction of the flow rises toward the electric resistance welding portion. Figure 1 schematically shows this situation.
is the metal flow on one side of the heat affected zone, and θ is called the metal flow rise angle. It goes without saying that the rising angle of this metal flow varies depending on the amount of upset. Such an electric resistance stitching part (hereinafter referred to as electric resistance sewing part)
In order to address the problem of poor toughness from a destructive standpoint, conventional methods have been proposed, such as Japanese Patent Application Laid-Open No. 1983-1983, which aim to improve the toughness by post-heat-treating the electrical resistance welded part, as mentioned above.
There is a method proposed in No. 86442. However, although this method has the effect of shifting the energy transition temperature or fracture surface transition temperature to a lower temperature side as shown in FIG. 2, it does not increase the impact value itself. Furthermore, the present inventors have confirmed that the impact value may vary widely due to the maximum heating temperature of post-heat treatment, uneven temperature distribution in the tube thickness direction, etc. Furthermore, there is a method proposed in Japanese Patent Application Laid-open No. 1673-1983, which aims to obtain an electrical resistance welded part with a high impact value by reducing the metal flow rise angle in the heat-affected zone, but the present inventor et al. Experiments have shown that when welding is performed with a small rise in metal flow, for example, with a small amount of upset, cold welding and penetrator welding defects tend to occur frequently at the electric resistance welding joint as shown in Figure 3. This tends to become a starting point for brittle fracture, which actually results in a loss of reliability in terms of safety.Furthermore, the number of cases where the product is determined to be defective in an ultrasonic test increases, resulting in a significant decrease in productivity. On the other hand, with regard to the chemical composition of steel sheets, it is known that reducing the amount of sulfur in the steel increases the shearing energy, especially in shear py specimens taken from the direction perpendicular to the rolling direction. In the process, the effects of heating, melting, and pressure welding have not been sufficiently studied, both qualitatively and quantitatively. Furthermore, it should be noted that the relationship between the impact value of the ERW welded part and the chemical composition of the material is completely unknown, and it is difficult to stably supply ERW pipes with so-called high-toughness ERW welded parts, including other toughness improvement methods. This has traditionally not been possible. The present invention has been made in view of these conventional unsolved problems and to solve them. That is, the present inventors have previously discovered that when the amount of oxygen in steel is small, MnS forms a shape (grain boundary eutectic type) during solidification.
It was thought that the steel tends to form a rectangular shape, elongates long after rolling or pressure welding, and increases the amount of A-based inclusions. However, in the electric resistance welded part that is heated, melted, and pressure welded, the amount of oxygen in the steel is Based on the completely new knowledge that the amount of A-based inclusions does not substantially increase even if the amount of oxygen is low, the effect of reducing the variation in impact values due to low oxygen content is added, thereby producing a synergistic effect. The company has obtained extremely new knowledge that it is possible to improve the quality, safety, and reliability of ERW steel pipes without sacrificing productivity. The gist of the present invention is to provide an electric resistance welded steel pipe manufactured from a steel strip whose chemical composition is mainly composed of iron, other ordinary alloying elements, and unavoidable impurities. 0.002% or less, oxygen 0.004% or less, and A-based nonmetallic inclusions measured according to JISG 0555 in the ERW welded part are 0.009% or less. It is an electric resistance welded steel pipe that can stably secure an impact value of 2.4 kg·m/cm 2 or more at a test temperature of -30°C in a 2 mm V notch seam pylon test with an electric resistance welded part after seam norming. The present invention will be explained in detail below. First, the usual alloying elements referred to in the present invention are C,
Si, Mn, and if necessary Ni, Cr, Mo,
It refers to Cu and small amounts of Al, Nb, V, Ti, etc., and the range is C: 0.01 to 0.29%, Si: 0.01 to 0.60
%, Mn: 0.3 to 2.5%, and Ni: if necessary.
3% or less, Cr: 2.5% or less, Mo: 0.7% or less,
Contains Cu: 0.5% or less, Al: 0.1% or less, Nb: 0.08% or less, V: 0.3% or less, Ti: 0.05% or less, especially API5A, 5AC, 5AX and
This includes the range of constituent elements of ERW steel pipes used for 5L and 5LX standard oil country tubular goods and line pipes. Next, in the present invention, the sulfur content is set to 0.002% or less and the oxygen content is set to 0.004% or less for the following reasons. That is, the present inventors set C: 0.08 as shown in Table 1.
~0.128%, Si: 0.18~0.40%, Mn: 1.10~1.35
%, Al: 0.027~0.05%, Nb: 0.016~0.035%,
V: 0.01~0.04%, Cr: 0.006~0.015%, Cu:
Strength of API5LX-X65 with 0.006 to 0.01% as a basic component (proof strength 45.6Kg/mm2 or more, tensile strength 54.1Kg/
mm 2 or more), the welding phenomenon known in Japanese Patent Application Laid-Open No. 111851/1983 was carried out using high-frequency electric resistance welding equipment with various sulfur and oxygen levels.
Welding was carried out using a type 2 welding phenomenon, with the upset amount set at a constant condition of 3 mm.
【表】
これは、純粋に化学成分等の衝撃値に及ぼす影
響のみを得るためには、他の衝撃値に影響を及ぼ
す要因を極力排除するか又は排除できない場合に
は影響の程度を略一定にしたうえでないと究明で
きないためである。
即ち、衝撃値に影響を及ぼす他の要因の一つに
前述したメタルフロー立上り角度があるが、第１
図に示す如き電縫部近傍のメタルフロー４は電縫
溶接において不可避的に存在するもので排除する
ことはできない。そこで、メタルフロー立上り角
度θを略一定にし、衝撃値の及ぼす影響を略一定
にするためには、メタルフロー立上り角度θを支
配しているアプセツト量と、更にアプセツト量は
溶接現象によつても変わるものであるから、溶接
現象を一定にした溶接をする必要があるわけであ
る。一方、第１図から分るように、メタルフロー
立上り角度θは板厚内の位置によつて変わつてい
るものであるから、一定した測定位置を決めてお
く必要がある。そこで、以下、本発明においては
メタルフロー角度は板厚の1/4位置におけるメタ
ルフローの角度とするものである。
尚、溶接現象は高速度カメラで撮影し、溶接後
第２種の溶接現象で溶接されていたことを確認し
ている。このようにアプセツト量及び溶接現象を
一定にし、メタルフロー立上り角を略一定にして
電縫溶接を行なつた帯鋼から小試片を切り出し、
熱処理を施した後第６図に示した如く電縫衝合部
のノツチを加工した電縫部２mmＶノツチ衝撃試片
５を作成して、試験温度−30℃で衝撃試験を行な
つた。試験結果を前記第１表に化学成分と合わせ
て示す。
更に、この結果を基に、硫黄、酸素量とシヤル
ピー最低衝撃値（試験温度−30℃）の関係をプロ
ツトすると第４図のようになる。同図から明らか
な如く、硫黄が0.002％以下で、酸素が0.0040％
以下とした帯鋼により得られた電縫部のシヤルピ
ー最低衝撃値は硫黄、酸素がこれ等より高いレベ
ルにあるものと比較し、飛躍的に向上している事
が分る。しかし、硫黄が0.002％以下で、酸素が
0.004％以下であるにもかかわらず衝撃値の一向
に改善されないもの（第４図中破線で囲んだ△印
及び〇印参照）があつた。
そこで、更に本発明者等はシヤルピー試片加工
に供した電縫溶接後の同一帯鋼の残部で、電縫部
についてJISG0555の非金属介在物の試験方法に
準拠して、非金属介在物の清浄度を判定した。測
定結果を前記第１表に化学成分及び衝撃値と対比
して示す。
この結果、鋼中の硫黄量が0.002％以下、酸素
量が0.0040％以下であつても前記JIS法に基づく
電縫溶接部におけるＡ系介在物量が0.009％超で
あるか、又は電縫部におけるＡ系介在物量が
0.009％以下であつても、鋼中の硫黄量が0.002％
超、酸素量が0.004％超のいずれか一方又は両方
であるとシームノルマ後の電縫部２mmＶノツチシ
ヤルピーの衝撃値を試験温度−30℃において、
2.4Kg・ｍ／cm2以上を安定して確保することが困
難であることが分つた。これは従来の知見では予
想もつかなかつた結果であり、よつて本発明の電
縫管においては、電縫溶接部のＡ系介在物量が
0.009％以下であることを必須要件とするもので
ある。
尚、硫黄量については0.0015％以下はメチレン
青法、他は燃焼赤外吸収法により求めた分析値で
あり、また酸素量については真空溶融法により求
めた分析値である。
また、第１表に示した化学成分及び衝撃値とＡ
系介在物量の測定結果は前記基本成分における一
例であつて、本発明に言う通常の合金元素範囲内
にある他の鋼についても、硫黄0.002％以下、酸
素0.004％以下でかつ、電縫溶接部におけるＡ系
介在物が0.009％以下であれば、硫黄、酸素、Ａ
系介在物がこれ等より高いレベルにあるものと比
較し、電縫部の衝撃靭性が向上すると言う普遍的
な結果が得られることは言うまでもない。
尚、鋼中の硫黄、酸素を低減する手段として
は、例えば取鍋中の溶鋼と別の電極間でアークを
発生させ、精錬するLF法、スラブ自体を電極と
して再溶解するESR法、Ca等をアルゴンガスと
共に溶鋼中に吹き込むTN法等を用いることがで
きる。
また、Ａ系介在物を0.009％以下に低減する手
段としては、圧延時にＡ系介在物化するMnSや
シリケートが鋼中に含まれていなければ良く、
Al脱酸の強化とCa吹込は有効である、ESR法で
溶製した鋼の介在物はほとんどＣ系とからなるか
ら、ESR法はＡ系介在物生成防止法として極め
て優れている。LF法は精錬中に介在物を浮上さ
せるのでやはりＡ系介在物の低減手段となる。
更に、電縫衝合部に含まれる溶接欠陥も一種の
Ａ系介在物と見なせるから、Ａ系介在物を0.009
％以下に収めるには溶接欠陥発生を防止しなけれ
ばならない。そのためには、造管の際アプセツト
を十分に加え、特開昭52−11851号公報に言う溶
接現象が第２種となるように、特開昭53−79746
号における高周波電縫溶接制御装置を利用して、
溶接入力を制御すれば良い。
本発明において、以上のような構成により電縫
衝合部の２mmＶノツチシヤルピー衝撃値を高くす
ることができるものであつて、希土類元素等の特
殊元素を添加する必要が全くないため、実用的価
値が極めて高い。
以下、実施例により本発明の効果をさらに具体
的に示す。
実施例
第２表は本発明と従来のAPI 5LX−X52の強度
（耐力36.6Kg／mm2以上、引張り強さ46.4Kg／mm2以
上）をもつ電縫管用帯鋼で製管したものの化学成
分と電縫溶接部のＡ系介在物量測定結果を対比し
て示したものである。[Table] In order to obtain only the effects of chemical components on the impact value, it is necessary to eliminate other factors that affect the impact value as much as possible, or if they cannot be eliminated, the degree of influence should be kept approximately constant. This is because it cannot be investigated unless it is determined. In other words, one of the other factors that affects the impact value is the metal flow rise angle mentioned above, but the first
The metal flow 4 near the electric resistance welding part as shown in the figure inevitably exists in electric resistance welding and cannot be eliminated. Therefore, in order to make the metal flow rise angle θ approximately constant and the effect of the impact value approximately constant, it is necessary to determine the amount of upset that governs the metal flow rise angle θ, and also the amount of upset depending on the welding phenomenon. Since the welding phenomenon varies, it is necessary to perform welding with a constant welding phenomenon. On the other hand, as can be seen from FIG. 1, the metal flow rise angle θ changes depending on the position within the plate thickness, so it is necessary to determine a constant measurement position. Therefore, hereinafter, in the present invention, the metal flow angle is defined as the angle of metal flow at a position of 1/4 of the plate thickness. The welding phenomenon was photographed using a high-speed camera, and it was confirmed that the welding occurred as a type 2 welding phenomenon after welding. A small specimen was cut out from the steel band that had been subjected to electric resistance welding while keeping the upset amount and welding phenomenon constant and the metal flow rising angle approximately constant.
After heat treatment, a 2 mm V-notch impact specimen 5 was prepared with a notch in the electrical resistance stitched abutting part as shown in FIG. 6, and an impact test was conducted at a test temperature of -30°C. The test results are shown in Table 1 above together with the chemical components. Furthermore, based on these results, the relationship between the amounts of sulfur and oxygen and the minimum Charpy impact value (test temperature -30°C) is plotted as shown in Figure 4. As is clear from the figure, sulfur is less than 0.002% and oxygen is 0.0040%.
It can be seen that the minimum shear py impact value of the electric resistance welded part obtained with the following steel strips is dramatically improved compared to those with higher levels of sulfur and oxygen. However, if sulfur is less than 0.002% and oxygen is
There were cases where the impact value was not improved at all (see △ and ○ marks surrounded by broken lines in Fig. 4) even though the impact value was 0.004% or less. Therefore, the present inventors further conducted a process to clean the non-metallic inclusions using the remaining part of the same steel strip after ERW welding that was subjected to the processing of the SHARPY specimen, in accordance with the test method for non-metallic inclusions in JISG0555. The degree was determined. The measurement results are shown in Table 1 above in comparison with the chemical components and impact values. As a result, even if the sulfur content in the steel is 0.002% or less and the oxygen content is 0.0040% or less, the amount of A-based inclusions in the ERW welded part is more than 0.009% based on the JIS method, or The amount of inclusions in the system
Even if the sulfur content is 0.009% or less, the amount of sulfur in steel is 0.002%.
If the oxygen content is more than 0.004% or both, the impact value of the 2mmV notched seam after seam norming at a test temperature of -30℃,
It was found that it was difficult to stably secure 2.4Kg・m/cm 2 or more. This is a result that could not have been predicted based on conventional knowledge, and therefore, in the ERW pipe of the present invention, the amount of A-based inclusions in the ERW welded portion is reduced.
The essential requirement is that the content be 0.009% or less. Regarding the amount of sulfur, 0.0015% or less is an analytical value determined by the methylene blue method, and the others are analytical values determined by a combustion infrared absorption method, and the amount of oxygen is an analytical value determined by a vacuum melting method. In addition, the chemical components and impact values shown in Table 1 and A
The measurement results of the amount of system inclusions are an example of the above basic components, and also for other steels within the range of normal alloying elements referred to in the present invention, sulfur is 0.002% or less, oxygen is 0.004% or less, and the electric resistance welded part If the A-based inclusions are 0.009% or less, sulfur, oxygen,
Needless to say, the general result is that the impact toughness of the electrical resistance welded part is improved compared to those with higher levels of system inclusions. In addition, methods for reducing sulfur and oxygen in steel include, for example, the LF method in which an arc is generated between the molten steel in a ladle and another electrode for refining, the ESR method in which the slab itself is used as an electrode to remelt it, Ca, etc. It is possible to use the TN method, etc., in which argon gas is injected into the molten steel. In addition, as a means of reducing A-based inclusions to 0.009% or less, it is sufficient that the steel does not contain MnS or silicates, which become A-based inclusions during rolling.
Strengthening Al deoxidation and Ca injection are effective, and inclusions in steel produced by the ESR method are mostly C-based, so the ESR method is extremely effective as a method for preventing the formation of A-based inclusions. Since the LF method causes inclusions to float during refining, it is also a means of reducing A-based inclusions. Furthermore, since the welding defects included in the electric resistance welding abutment can also be considered as a type of A-based inclusion, the A-based inclusion is 0.009.
% or less, it is necessary to prevent welding defects from occurring. In order to do this, sufficient upset is added during pipe making, and the welding phenomenon described in JP-A-52-11851 is of the second type.
Using the high frequency electric resistance welding control device in
All you have to do is control the welding input. In the present invention, with the above-described configuration, it is possible to increase the 2 mmV notch mechanical strength impact value of the electric resistance stitching abutment part, and there is no need to add special elements such as rare earth elements, so it has no practical value. Extremely high. Hereinafter, the effects of the present invention will be illustrated more specifically by Examples. Example Table 2 shows the chemical composition of pipes made from steel strips for electric resistance welded pipes having the strengths of the present invention and the conventional API 5LX-X52 (yield strength 36.6 Kg/mm 2 or more, tensile strength 46.4 Kg/mm 2 or more). This figure shows a comparison of the results of measuring the amount of A-based inclusions in the electric resistance welded area.
【表】
本発明材及び従来材の製管条件は管径323.9
φ、肉厚12.7t、突合せ型状Ｉ型、溶接速度25
ｍ／minを一定にしたうえで、板厚の1/4の位置
におけるメタルフロー立上り角度がいろいろの角
度になるように溶接現象とアプセツト量を変えて
電縫溶接を行なつた、溶接後は管表面で最高加熱
温度930℃とし、電縫部全体がオーステナイト化
温度まで加熱されるようにシームノルマ処理を施
した。
シームノルマ後、電縫部２mmＶノツチシヤルピ
ー試片を採取し、試験温度−30℃で衝撃試験を行
なつた。シヤルピー最低衝撃値とメタルフロー立
上り角度の関係で試験結果を整理したものを第５
図に示す。
従来のものは第５図の▲、■、●、×などが示
すように、従来から知られている傾向の如く、メ
タルフロー立上り角度が大きくなる程衝撃値が低
下し、しかもその水準も全体にかなり低いもので
あつたのに対し、本発明のもの（第５図中〇印、
△印）ではメタルフロー立上り角度の変動に殆ど
依存しないで、しかも従来のレベルより極めて高
い衝撃値レベルを維持していることが明らかであ
る。これは、溶接現象、アプセツト量等によつて
シヤルピー最低衝撃値があまり変わらず一様に高
靭性電縫衝合部を有する電縫鋼管の製造が可能で
あると言うことで、このことは全ての電縫溶接ミ
ルで普遍的に製管できると言うことである。
更に、従来試みられているようなメタルフロー
立上り角度を小さくして靭性向上をはかる必要が
ないものであるからペネトレーター等の溶接欠陥
が少ない電縫溶接ができ生産性をも高くして製管
でき、工業的に極めて優れた技術的価値があるも
のである。
また、本発明の電縫鋼管においては、電縫部に
おけるＡ系非金属介在物（主としてMnS）の量
を極めて低く制限しているため、かかる介在物に
起因して溶接部が選択的に腐食するいわゆる溝食
に対しても優れた耐食性を示すことはいうまでも
ない。
尚、本発明の技術は電縫鋼管の製造以外にも例
えば形鋼などの電縫溶接にも適用することが可能
である。[Table] Pipe manufacturing conditions for the present invention material and conventional material are pipe diameter 323.9
φ, wall thickness 12.7t, butt type I type, welding speed 25
With m/min constant, electric resistance welding was performed by changing the welding phenomenon and upset amount so that the metal flow rise angle at the 1/4th position of the plate thickness varied. The maximum heating temperature was set at 930°C on the tube surface, and seam norm treatment was applied so that the entire electrical resistance welded part was heated to the austenitizing temperature. After the seam norming, a 2 mm V-notch seam specimen was taken from the electrical resistance welded portion and subjected to an impact test at a test temperature of -30°C. The fifth section summarizes the test results in terms of the relationship between the minimum impact value of Shapey and the rise angle of metal flow.
As shown in the figure. As shown by the ▲, ■, ●, ×, etc. in Figure 5, in the conventional model, the impact value decreases as the metal flow rise angle increases, as is the conventionally known tendency, and the overall level is also lower. In contrast, the values of the present invention (marked with ○ in Figure 5,
It is clear that the impact value level (marked with △) is almost independent of fluctuations in the metal flow rise angle and maintains an extremely higher impact value level than the conventional level. This means that it is possible to manufacture ERW steel pipes that have uniformly high toughness ERW abutments without changing the minimum shear strength impact value much due to welding phenomena, upset amount, etc. This means that pipes can be universally manufactured using the ERW welding mill. Furthermore, since there is no need to improve toughness by reducing the rise angle of the metal flow, which has been attempted in the past, it is possible to perform electric resistance welding with fewer weld defects such as penetrators, and to manufacture pipes with high productivity. , which has extremely excellent technical value industrially. In addition, in the electric resistance welded steel pipe of the present invention, the amount of A-based nonmetallic inclusions (mainly MnS) in the electric resistance welded portion is limited to an extremely low level, so that the welded portion may selectively corrode due to such inclusions. Needless to say, it also exhibits excellent corrosion resistance against so-called groove corrosion. Note that the technique of the present invention can be applied not only to the production of electric resistance welded steel pipes but also to electric resistance welding of section steel and the like.
第１図は電縫溶接部近傍の横断面を示す模式
図、第２図は溶接したままのものと後熱処理を施
したものの電縫部衝撃試験結果の関係を示す図、
第３図はメタルフロー立上り角度と欠陥発生率の
関係を示す図、第４図は帯鋼中の硫黄、酸素量と
シヤルピー最低衝撃値の関係を示す図、第５図は
メタルフロー立上り角度とシヤルピー最低衝撃値
の関係を示す図、第６図ａ，ｂは電縫部衝撃試片
作成法を示す図である。
１……電縫部衝合部、２，２′……熱影響部、
３，３′……母材部、４……メタルフロー、５…
…２mmＶノツチ衝撃試片、θ……メタルフロー立
上り角度。
Fig. 1 is a schematic diagram showing a cross section near the ERW welded part, Fig. 2 is a diagram showing the relationship between the impact test results of the ERW part as welded and after heat treatment.
Figure 3 is a diagram showing the relationship between metal flow rise angle and defect occurrence rate, Figure 4 is a diagram showing the relationship between sulfur and oxygen content in steel strip and the minimum shear py impact value, and Figure 5 is a graph showing the relationship between metal flow rise angle and defect occurrence rate. Figures 6a and 6b are diagrams showing the relationship between the shear pee minimum impact value and the method for preparing an impact test piece for the electrical resistance welded part. 1...Erw seam abutment part, 2, 2'...Heat affected zone,
3, 3'...Base metal part, 4...Metal flow, 5...
...2mm V-notch impact specimen, θ...metal flow rise angle.
Claims (1)
及び不可避的不純物からなる帯鋼を素材として製
造された電縫鋼管にあつて、該不純物元素のう
ち、硫黄0.002％以下、酸素0.004％以下であり、
かつ、電縫溶接部におけるJISG 0555により測定
されるＡ系非金属介在物が0.009％以下であるこ
とを特徴とする電縫衝合部靭性の優れた電縫鋼
管。1. For electric resistance welded steel pipes manufactured from steel strips whose chemical composition is mainly composed of iron, other ordinary alloying elements, and unavoidable impurities, sulfur is 0.002% or less and oxygen is 0.004% or less of the impurity elements. and
An electric resistance welded steel pipe having excellent toughness at an electric resistance welded joint, characterized in that the amount of A-based nonmetallic inclusions measured according to JISG 0555 in the electric resistance welded seam is 0.009% or less.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2030078A JPS54112369A (en) | 1978-02-23 | 1978-02-23 | Electric welded steel tube provided with high toughness electric welded zone |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2030078A JPS54112369A (en) | 1978-02-23 | 1978-02-23 | Electric welded steel tube provided with high toughness electric welded zone |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS54112369A JPS54112369A (en) | 1979-09-03 |
| JPS6260462B2 true JPS6260462B2 (en) | 1987-12-16 |
Family
ID=12023291
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP2030078A Granted JPS54112369A (en) | 1978-02-23 | 1978-02-23 | Electric welded steel tube provided with high toughness electric welded zone |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS54112369A (en) |
Families Citing this family (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH0724940B2 (en) * | 1984-04-09 | 1995-03-22 | 新日本製鐵株式会社 | ERW steel pipe with excellent sour resistance |
| JPH0617542B2 (en) * | 1985-03-13 | 1994-03-09 | 日新製鋼株式会社 | High strength ERW steel pipe with good pipe expandability |
| JPS61213344A (en) * | 1985-03-18 | 1986-09-22 | Kawasaki Steel Corp | High toughness seamless steel pipe |
| JPS62274049A (en) * | 1986-05-22 | 1987-11-28 | Nippon Steel Corp | Continuously-cast steel for resistance welded tube excellent in sour resistance and toughness at low temperature |
| JP2974846B2 (en) * | 1991-06-14 | 1999-11-10 | 株式会社日本製鋼所 | Low temperature structural steel |
Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5118912A (en) * | 1974-08-08 | 1976-02-14 | Nippon Steel Corp | RENZOKUCHUZOZAINYORU KOKYODODEN HOKOKAN |
-
1978
- 1978-02-23 JP JP2030078A patent/JPS54112369A/en active Granted
Patent Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5118912A (en) * | 1974-08-08 | 1976-02-14 | Nippon Steel Corp | RENZOKUCHUZOZAINYORU KOKYODODEN HOKOKAN |
Also Published As
| Publication number | Publication date |
|---|---|
| JPS54112369A (en) | 1979-09-03 |
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