JPH0387317A - Production of steel tube or square steel tube having low yield ratio - Google Patents
Production of steel tube or square steel tube having low yield ratioInfo
- Publication number
- JPH0387317A JPH0387317A JP10796390A JP10796390A JPH0387317A JP H0387317 A JPH0387317 A JP H0387317A JP 10796390 A JP10796390 A JP 10796390A JP 10796390 A JP10796390 A JP 10796390A JP H0387317 A JPH0387317 A JP H0387317A
- Authority
- JP
- Japan
- Prior art keywords
- low
- yield ratio
- steel tube
- steel
- low yield
- 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.)
- Pending
Links
- 229910000831 Steel Inorganic materials 0.000 title claims abstract description 43
- 239000010959 steel Substances 0.000 title claims abstract description 43
- 238000004519 manufacturing process Methods 0.000 title claims description 19
- 238000001816 cooling Methods 0.000 claims abstract description 32
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 13
- 238000000034 method Methods 0.000 claims abstract description 12
- 229910001209 Low-carbon steel Inorganic materials 0.000 claims abstract description 8
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims abstract description 6
- 229910052799 carbon Inorganic materials 0.000 claims abstract description 6
- 238000005496 tempering Methods 0.000 claims description 11
- 229910000851 Alloy steel Inorganic materials 0.000 claims description 5
- 238000010438 heat treatment Methods 0.000 abstract description 11
- 229910045601 alloy Inorganic materials 0.000 abstract 1
- 239000000956 alloy Substances 0.000 abstract 1
- 230000000694 effects Effects 0.000 description 6
- 229910001566 austenite Inorganic materials 0.000 description 5
- 238000005482 strain hardening Methods 0.000 description 4
- 229910000859 α-Fe Inorganic materials 0.000 description 4
- 238000010276 construction Methods 0.000 description 3
- 238000000465 moulding Methods 0.000 description 3
- 238000005260 corrosion Methods 0.000 description 2
- 230000007797 corrosion Effects 0.000 description 2
- 230000007423 decrease Effects 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- 239000000203 mixture Substances 0.000 description 2
- 238000001556 precipitation Methods 0.000 description 2
- 238000007670 refining Methods 0.000 description 2
- 230000009466 transformation Effects 0.000 description 2
- 229910000885 Dual-phase steel Inorganic materials 0.000 description 1
- UCKMPCXJQFINFW-UHFFFAOYSA-N Sulphide Chemical compound [S-2] UCKMPCXJQFINFW-UHFFFAOYSA-N 0.000 description 1
- 238000005275 alloying Methods 0.000 description 1
- 230000033228 biological regulation Effects 0.000 description 1
- 150000001875 compounds Chemical class 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 229910000734 martensite Inorganic materials 0.000 description 1
- 238000009740 moulding (composite fabrication) Methods 0.000 description 1
- 239000003129 oil well Substances 0.000 description 1
- 238000003303 reheating Methods 0.000 description 1
- 238000005728 strengthening Methods 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 230000002195 synergetic effect Effects 0.000 description 1
Abstract
Description
【発明の詳細な説明】
（産業上の利用分野）
本発明は、降伏比の低い鋼管または角管の製造方法に関
するものである。DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method of manufacturing a steel pipe or square pipe with a low yield ratio.
（従来の技術）
近年鉄鋼材料を扱う各分野にわたって、競争力向上のた
めの使用特性の向上、製造コストの低減など各種の要求
が高まっている。(Prior Art) In recent years, various demands have been increasing across various fields that handle steel materials, such as improving usage characteristics to improve competitiveness and reducing manufacturing costs.
このうち建築分野では、構造物の安全性向上のため、特
に耐震性向上のために降伏比の低下が望まれている。こ
れまでは主に厚板分野でこの要求が強かったが、最近で
は鋼管分野でこの要求かたかまっている。低降伏比を有
する厚鋼板の製造方法に関しては、種々の方法が検討さ
れているが、残念ながら鋼管の分野では、少なくとも建
築用として検討された例はほとんどないのが現状である
。例えば電縫鋼管は、ホットコイルを成形して製造する
が、成形の際の加工硬化により降伏比が上昇するため、
降伏比の低い鋼管の製造には、不利な製造方法とされて
いる。例えば、低降伏比油井用電縫鋼管の製造方法とし
て、特開昭５７−１８１１８号があるが、低降伏比、を
得るためにＣ量をかなり増加しており（Ｃ量： ０．２
８〜０．４８％）、溶接性の観点からＣｅｑに規定のあ
る建築構造用としては、適用できない。また同様に、低
降伏比高張力電縫鋼管の製造方法として、特開昭５７−
１６１１９号があるが、これはホットコイルの段階で極
低ＹＲ鋼を製造し、電縫鋼管を製造する際の加工硬化を
押えるために、歪量をかなり制限しているが、実操業で
はかなり困難が伴う。Among these, in the field of construction, it is desired to reduce the yield ratio in order to improve the safety of structures, especially in order to improve their seismic resistance. Until now, this requirement has been strong mainly in the thick plate field, but recently this requirement has become stronger in the steel pipe field. Various methods have been studied for manufacturing thick steel plates with a low yield ratio, but unfortunately, in the field of steel pipes, there are currently almost no examples of such methods being studied, at least for construction purposes. For example, ERW steel pipes are manufactured by forming hot coils, but the yield ratio increases due to work hardening during forming.
It is considered to be a disadvantageous manufacturing method for manufacturing steel pipes with a low yield ratio. For example, there is a method for manufacturing ERW steel pipes for oil wells with a low yield ratio in JP-A-57-18118, but in order to obtain a low yield ratio, the amount of C is increased considerably (amount of C: 0.2
8 to 0.48%), it cannot be applied to architectural structures as specified by Ceq from the viewpoint of weldability. Similarly, as a method for manufacturing low yield ratio, high tensile resistance welded steel pipes, JP-A-57-
There is No. 16119, which manufactures ultra-low YR steel at the hot coil stage and limits the amount of strain considerably in order to suppress work hardening when manufacturing ERW steel pipes, but in actual operation it is considerably It is difficult.
（発明が解決しようとする課題）
建築用低降伏比鋼管または、角管として、弓張り強さ４
０〜６０キロレベルで降伏比７５％以下という要求があ
るが、現状の製造方法では製造が不可能である。つまり
、ホットコイルを丸く成形しただけで製造する非調質型
、いわゆるアズロール型では、その成形時の加工硬化の
ために、また調質型いわゆるＱＴ型では、その組織が焼
戻しマルテンサイトとなるため、降伏比７５％以下は達
成されていない。(Problem to be solved by the invention) As a low yield ratio steel pipe for construction or a square pipe, the bow strength is 4.
There is a requirement for a yield ratio of 75% or less at the 0-60 kg level, but this is impossible with current manufacturing methods. In other words, in the non-tempered type, the so-called azurol type, which is manufactured by simply forming a hot coil into a round shape, the structure is due to work hardening during forming, and in the tempered type, so-called QT type, the structure becomes tempered martensite. , a yield ratio of 75% or less has not been achieved.
（課題を解決するための手段）
そこで本発明者らは、降伏比を低下させるために、多数
の実験と詳細な検討を加えた結果、降伏比を低下させる
ためには、鋼のミクロ組織をフェライトと第２相の炭化
物の２相組織にする必要性を確認した。さらに、降伏比
を下げるためには、降伏点を下げ、引張り強さを高める
ことが重要であることも確認した。(Means for Solving the Problems) Therefore, the present inventors conducted numerous experiments and detailed studies in order to reduce the yield ratio. The necessity of creating a two-phase structure consisting of ferrite and a second phase of carbide was confirmed. Furthermore, it was confirmed that in order to lower the yield ratio, it is important to lower the yield point and increase the tensile strength.
本発明は、このような知見に基き、低降伏比を有する鋼
管または角管の製造を可能にしたもので、その要旨とす
るところは、低炭素鋼または低炭素低合金鋼管（または
角管）をＡｃ３以上に加熱し、その後空冷してＡｒｃ−
２０℃〜Ａｒ３−２５０℃から３０℃／ｓｅｅ以上の冷
却速度で水冷し、その後必要に応じて２００〜６００℃
の温度範囲で焼き戻しすることを特徴とする、降伏比の
低い鋼管（または角管〉の製造方法である。Based on this knowledge, the present invention has made it possible to manufacture steel pipes or square pipes with a low yield ratio. is heated to Ac3 or higher, then air cooled to create Arc-
Water cooling from 20°C to Ar3-250°C at a cooling rate of 30°C/see or higher, then 200 to 600°C as necessary
This is a method for manufacturing steel pipes (or rectangular pipes) with a low yield ratio, which is characterized by tempering at a temperature range of .
（作 用）
本発明においては、加熱温度を＾Ｃ３変態点以上にして
、完全なオーステナイト１相にして、バイブ戒心やその
後の角管成形での加工硬化の影響を完全に除去し、その
後の＾「３変態点以下までの空冷でフェライトを析出さ
せ、その後の水冷を組み合わせることによって、２相鋼
化を達成することに成功している。(Function) In the present invention, the heating temperature is set to the C3 transformation point or higher to form a complete austenite single phase, completely eliminating the influence of work hardening in the vibrating process and subsequent square tube forming. ^ “By combining ferrite precipitation with air cooling to below the 3rd transformation point and subsequent water cooling, we have succeeded in achieving dual phase steel.
さらに焼き戻し温度を低くすることによって、第２相の
部分を必要以上に軟化させないことの相乗的効果により
、降伏比の低い鋼管（または角管）の製造を可能にした
ものである。Furthermore, by lowering the tempering temperature, the synergistic effect of not softening the second phase part more than necessary makes it possible to manufacture steel pipes (or square pipes) with a low yield ratio.
次に本発明の鋼管成形・角管成形・加熱・冷却・テンパ
ーの条件について述べる。Next, the conditions for steel pipe forming, square pipe forming, heating, cooling, and tempering of the present invention will be described.
まず、鋼管の成形およびその後の角管成形については、
特に規定はなくどのような成形でも許容される。例えば
鋼管はその製造方法から、シームレス鋼管、電縫鋼管、
ＵＯｔＩ４管、スパイラル鋼管、鍛接管等に分類できる
が、本発明はこれらどの製造方法でも許容される。ホッ
トコイルのような板から直接角管に成形して溶接したも
のでも、もちろん許容される。これは、その後の熱処理
での加熱温度を加工歪が除去される温度に規定するため
である。次に成形後加熱温度をＡｃ、以上にしたのは、
完全なオーステナイト１相組織として成形歪の完全除去
を狙ったためである。First, regarding steel pipe forming and subsequent square tube forming,
There are no particular regulations, and any molding is acceptable. For example, steel pipes are manufactured using different manufacturing methods, such as seamless steel pipes, electric resistance welded steel pipes,
Although it can be classified into UOtI4 pipes, spiral steel pipes, forge welded pipes, etc., any of these manufacturing methods are acceptable in the present invention. Of course, it is also acceptable to directly form a square tube from a plate such as a hot coil and weld it. This is to set the heating temperature in the subsequent heat treatment to a temperature at which processing strain is removed. Next, the heating temperature after molding was set to Ac or higher.
This is because the aim was to completely eliminate molding strain by creating a complete austenite single-phase structure.
加熱後に空冷を行なうのは、冷却前に適量のフェライト
を析出させて、完全な２相鋼化を狙ったものである。The purpose of performing air cooling after heating is to precipitate an appropriate amount of ferrite before cooling, with the aim of creating a complete duplex steel.
冷却開始温度の上限をＡｒ３−２（１℃としたのは降伏
点を低くするためであり、下限をＡｒ３−２５０℃とし
たのは、これ以下の低い温度から冷却すると加速冷却の
効果がうすく引張り強さが下がり、強度確保が困難なた
めである。The reason why the upper limit of the cooling start temperature was set to Ar3-2 (1℃) was to lower the yield point, and the lower limit was set to Ar3-250℃ because the effect of accelerated cooling is weak when cooling from a lower temperature than this. This is because the tensile strength decreases and it is difficult to secure strength.
Ａｒ３−２０〜Ａｒ５−２５Ｑに空冷後の水冷は、再加
熱時にオーステナイト化してＣの濃化した部分を焼入組
織とすることで充分硬化させ、引張り強さを高め低降伏
比を得るためである。水冷が不十分だと、焼入組織が充
分に硬化せず、結果として低降伏比が得られないため、
冷却速度を３０℃／ｓｅｅ以上に規定した。Water cooling after air cooling for Ar3-20 to Ar5-25Q is done in order to fully harden the part by turning it into austenite during reheating and making the C-enriched part a quenched structure, increasing the tensile strength and obtaining a low yield ratio. be. If water cooling is insufficient, the quenched structure will not harden sufficiently, resulting in a low yield ratio.
The cooling rate was set at 30° C./see or higher.
ところで、鋼種によっては加熱後水冷だけでは靭性のよ
くないものがあり、靭性改善のために水冷後焼き戻し処
理の必要な場合がある。その際焼き戻し温度としては、
フェライトと第２相の炭化物の２相組織について、その
前の水冷で充分硬化した第２相部分をあまり高温で焼き
戻すと軟化しすぎ、これが引張り強さの低下つまり降伏
比の上昇の原因となるため、上限を６００℃とした。し
かし焼き戻し温度が低くて、２００℃未満になるとほと
んど焼き戻しの効果がなくなり、靭性が改善さ゛れない
場合があるため、その下限を２００℃とした。By the way, depending on the type of steel, there are some steels whose toughness is not good only by water cooling after heating, and it may be necessary to perform tempering treatment after water cooling in order to improve the toughness. At that time, the tempering temperature is
Regarding the two-phase structure of ferrite and second phase carbide, if the second phase part, which has been sufficiently hardened by water cooling, is tempered at too high a temperature, it will become too soft, which is the cause of the decrease in tensile strength and the increase in yield ratio. Therefore, the upper limit was set to 600°C. However, if the tempering temperature is too low to be less than 200°C, the tempering effect will be almost gone and the toughness may not be improved, so the lower limit was set at 200°C.
本発明法は低炭素鋼またはこれに特殊元素を添加した低
炭素低合金鋼に適用して好結果を得ることができる。好
ましい成分組成としては、Ｃ： ０．０５〜０．３０％
Ｓｔ ： ０．０２〜０．５０％
Ｍｎ ： ０．５０〜２．００％
Ａ！ｌ： ０．００１〜０．１００％
Ｎ ： ０．０００５〜０．０１００％を基本成分とす
る低炭素鋼、または前記基本成分の他に強度鋼の要求特
性によって、
Ｃｕ：２．０％以下
Ｎｌ ： ９．５％以下
Ｃｒ ： ５．５％以下
Ｍｏ：２．０％以下
Ｎｂ ： ０．１５％以下
Ｖ ： ０．３％以下
Ｔｉ ： ０．１５％以下
Ｂ ： ０．０００３〜０．００３０％Ｃａ ：
０．００８０％以下
の１種または２種以上添加してもよい。The method of the present invention can be applied to low carbon steel or low carbon low alloy steel to which special elements are added with good results. Preferred component compositions include: C: 0.05-0.30% St: 0.02-0.50% Mn: 0.50-2.00% A! L: 0.001-0.100% N: Low carbon steel with a basic component of 0.0005-0.0100%, or depending on the required characteristics of the strength steel in addition to the basic components, Cu: 2.0% or less Nl: 9.5% or less Cr: 5.5% or less Mo: 2.0% or less Nb: 0.15% or less V: 0.3% or less Ti: 0.15% or less B: 0.0003 to 0. 0030%Ca:
One or more types may be added in an amount of 0.0080% or less.
Ｃｕは強度上昇、耐食性向上に有用で添加されるが、２
．０％を越えて添加しても強度の上昇代がほとんどなく
なるので、含有量の上限は２．０％とする。Cu is added because it is useful for increasing strength and improving corrosion resistance, but 2
．． Even if it is added in excess of 0%, there is almost no increase in strength, so the upper limit of the content is set at 2.0%.
Ｎｉは低温靭性の改善に有用で添加されるが、高価な元
素であるため含有量は９．５％を上限とする。Ni is added because it is useful for improving low-temperature toughness, but since it is an expensive element, the upper limit of the content is 9.5%.
Ｃ「は強度上昇や耐食性向上に有用で添加されるが、多
くなると低温靭性、溶接性を阻害するため含有量は５．
５％を上限とする。C is added because it is useful for increasing strength and improving corrosion resistance, but if too much it impedes low-temperature toughness and weldability, so the content is 5.
The upper limit is 5%.
Ｍｏは強度上昇に有用であるが、多くなると溶接性を阻
害するため含有量は２．０％を上限とする。Mo is useful for increasing strength, but if too much Mo inhibits weldability, the upper limit of the content is 2.0%.
Ｎｂはオーステナイト粒の細粒化や強度上昇に有用で添
加されるが、多くなると溶接性を阻害するので含有量の
上限は０．１５％とする。Nb is added because it is useful for refining austenite grains and increasing strength, but if too much, it impedes weldability, so the upper limit of the content is set to 0.15%.
■は析出強化に有用であるが、多くなると溶接性を阻害
するため、含有量は０．３％を上限とする。(2) is useful for precipitation strengthening, but if too large, it impedes weldability, so the upper limit of content is 0.3%.
Ｔｉはオーステナイト粒の細粒化に有用で添加されるが
、多くなると溶接性を阻害するため、含有量は０．３％
を上限とする。Ti is added because it is useful for refining austenite grains, but if it increases, it inhibits weldability, so the content is limited to 0.3%.
is the upper limit.
Ｂは微量の添加によって、鋼の焼入性を著しく高める効
果を有する。この効果を有効に得るためには、少なくと
もＱ、（１０００％を添加することが必要である。しか
し過多に添加するとＢ化合物を生成して、靭性を劣化さ
せるので、上限は０．００３Ｑ％とする。B has the effect of significantly increasing the hardenability of steel when added in a small amount. In order to effectively obtain this effect, it is necessary to add at least Q (1000%).However, if too much is added, B compounds are generated and the toughness is deteriorated, so the upper limit is 0.003Q%. do.
Ｃａは硫化物系介在物の形態制御に有用で添加されるが
、多くなると鋼中介在物を形成し鋼の性質を悪化させる
ため、含有量はｏ、ｏｏａ％を上限とする。Ca is added because it is useful for controlling the form of sulfide-based inclusions, but if too much Ca forms inclusions in the steel and deteriorates the properties of the steel, the upper limit of the content is set at o, ooa%.
（実 施 例）
第１表に供試材の化学成分を示し、第２表に鋼管または
角管のサイズ、熱処理条件と、得られた鋼管の１１＆械
的性質を示す。(Example) Table 1 shows the chemical composition of the test materials, and Table 2 shows the size of the steel pipe or square pipe, heat treatment conditions, and mechanical properties of the obtained steel pipe.
第２表で示しに鋼管Ｎｏ、ＡＩ、Ｂｌ、Ｃ１゜１）１．
Ｅｌ、Ｆｌ、Ｇｌ、）１１．Ｉ １．Ｊｌ。Table 2 shows the steel pipe No., AI, Bl, C1゜1)1.
El, Fl, Gl,)11. I 1. Jl.
Ｋｌ、Ｌｌ、Ｍｌ、Ｎｌ、０１．Ｐｉ、Ｑｌ。Kl, Ll, Ml, Nl, 01. Pi, Ql.
Ｒ１，３１，ＴＩ、ｔＪｌ、Ｖｌはそれぞれ本発明実施
鋼であり、本発明の狙いとする低降伏比（降伏比７０％
以下）を達成している。R1, 31, TI, tJl, and Vl are steels according to the present invention, and have a low yield ratio (yield ratio of 70%), which is the aim of the present invention.
The following) have been achieved.
これに対し、Ａ２は水冷開始温度が高すぎるため降伏比
が高くなっている。Ａ３は水冷開始温度が低すぎるため
強度が低くなっている。On the other hand, A2 has a high yield ratio because the water cooling start temperature is too high. A3 has low strength because the water cooling start temperature is too low.
Ａ４は加熱後の冷却速度が不足のため降伏比が高くなっ
ている。Ａ５は焼き戻し温度が高すぎるため降伏比が高
くなっている。A4 has a high yield ratio because the cooling rate after heating is insufficient. A5 has a high yield ratio because the tempering temperature is too high.
また、Ｂ２は焼き戻し温度が高すぎるため降伏比が高く
なっている。Ｃ２は冷却速度が不足のため降伏比が高く
なっている。Ｂ２は加熱温度と冷却開始温度が低すぎる
ため強度が低くなっている。Further, B2 has a high yield ratio because the tempering temperature is too high. C2 has a high yield ratio due to insufficient cooling rate. B2 has low strength because the heating temperature and cooling start temperature are too low.
（発明の効果）
以上詳細に説明した通り、本発明は特別に高価な合金元
素を使用することなく、５０ｋｇｆ／ｕ＋ｍ２以上の高
強度を有する低降伏比鋼管または角管を、安価に製造可
能としたもので、産業上その効果は大である。(Effects of the Invention) As explained in detail above, the present invention enables low yield ratio steel pipes or rectangular pipes having a high strength of 50 kgf/u+m2 or more to be manufactured at low cost without using particularly expensive alloying elements. As a result, the industrial effects are significant.
他４名4 others
Claims (1)
℃〜Ａｒ＿３−２５０℃から３０℃／ｓｅｃ以上の冷却
速度で水冷することを特徴とする、降伏比の低い鋼管の
製造方法。２ 低炭素鋼または低炭素低合金鋼管を、 Ａｃ＿３以上に加熱し、その後空冷してＡｒ＿３−２０
℃〜Ａｒ＿３−２５０℃から３０℃／ｓｅｃ以上の冷却
速度で水冷し、その後２００〜６００℃の温度範囲で焼
き戻しすることを特徴とする、降伏比の低い鋼管の製造
方法。 ３ 低炭素鋼または低炭素低合金鋼管を、 Ａｃ＿３以上に加熱し、その後空冷してＡｒ＿３−２０
℃〜Ａｒ＿３−２５０℃から３０℃／ｓｅｃ以上の冷却
速度で水冷することを特徴とする、降伏比の低い角管の
製造方法。４ 低炭素鋼または低炭素低合金鋼管を、 Ａｃ＿３以上に加熱し、その後空冷してＡｒ＿３−２０
℃〜Ａｒ＿３−２５０℃から３０℃／ｓｅｃ以上の冷却
速度で水冷し、その後２００〜６００℃の温度範囲で焼
き戻しすることを特徴とする、降伏比の低い角管の製造
方法。[Claims] 1. Low carbon steel or low carbon low alloy steel pipe is heated to Ac_3 or higher and then air cooled to Ar_3-20.
A method for manufacturing a steel pipe with a low yield ratio, characterized by water cooling from ℃ to Ar_3-250℃ at a cooling rate of 30℃/sec or more. 2. Heat low carbon steel or low carbon low alloy steel pipe to Ac_3 or higher, then air cool to Ar_3-20.
A method for manufacturing a steel pipe with a low yield ratio, characterized by water cooling from ℃~Ar_3-250℃ at a cooling rate of 30℃/sec or more, and then tempering in a temperature range of 200 to 600℃. 3. Heat low carbon steel or low carbon low alloy steel pipe to Ac_3 or higher, then air cool to Ar_3-20.
A method for manufacturing a rectangular tube with a low yield ratio, characterized by water cooling from ℃ to Ar_3-250℃ at a cooling rate of 30℃/sec or more. 4. Heat low carbon steel or low carbon low alloy steel pipe to Ac_3 or higher, then air cool to Ar_3-20.
A method for manufacturing a rectangular tube with a low yield ratio, characterized by water-cooling from °C to Ar_3-250 °C at a cooling rate of 30 °C/sec or more, and then tempering in a temperature range of 200 to 600 °C.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP15017989 | 1989-06-13 | ||
| JP1-150179 | 1989-06-13 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH0387317A true JPH0387317A (en) | 1991-04-12 |
Family
ID=15491232
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP10796390A Pending JPH0387317A (en) | 1989-06-13 | 1990-04-24 | Production of steel tube or square steel tube having low yield ratio |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH0387317A (en) |
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH06192741A (en) * | 1992-12-28 | 1994-07-12 | Kubota Corp | Method for heat-treating thick walled cast steel pipe |
| JPH06192739A (en) * | 1992-12-25 | 1994-07-12 | Kubota Corp | Method for heat-treating thick welled cast steel pipe |
| JPH06192740A (en) * | 1992-12-28 | 1994-07-12 | Kubota Corp | Method for heat-treating thick walled cast steel pipe |
| JP2012021181A (en) * | 2010-07-12 | 2012-02-02 | Nippon Steel Corp | Heat treatment method and heat treating facility for steel pipe |
| EP2853615A1 (en) * | 2003-06-12 | 2015-04-01 | JFE Steel Corporation | Low yield ratio, high strength, high toughness, thick steel plate and welded steel pipe, and method for manufacturing the same |
-
1990
- 1990-04-24 JP JP10796390A patent/JPH0387317A/en active Pending
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH06192739A (en) * | 1992-12-25 | 1994-07-12 | Kubota Corp | Method for heat-treating thick welled cast steel pipe |
| JPH06192741A (en) * | 1992-12-28 | 1994-07-12 | Kubota Corp | Method for heat-treating thick walled cast steel pipe |
| JPH06192740A (en) * | 1992-12-28 | 1994-07-12 | Kubota Corp | Method for heat-treating thick walled cast steel pipe |
| EP2853615A1 (en) * | 2003-06-12 | 2015-04-01 | JFE Steel Corporation | Low yield ratio, high strength, high toughness, thick steel plate and welded steel pipe, and method for manufacturing the same |
| JP2012021181A (en) * | 2010-07-12 | 2012-02-02 | Nippon Steel Corp | Heat treatment method and heat treating facility for steel pipe |
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