JP2010242163A - Method for manufacturing martensitic stainless steel seamless steel tube for oil well pipe - Google Patents
Method for manufacturing martensitic stainless steel seamless steel tube for oil well pipe Download PDFInfo
- Publication number
- JP2010242163A JP2010242163A JP2009092055A JP2009092055A JP2010242163A JP 2010242163 A JP2010242163 A JP 2010242163A JP 2009092055 A JP2009092055 A JP 2009092055A JP 2009092055 A JP2009092055 A JP 2009092055A JP 2010242163 A JP2010242163 A JP 2010242163A
- Authority
- JP
- Japan
- Prior art keywords
- less
- stainless steel
- martensitic stainless
- temperature
- tempering
- 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.)
- Granted
Links
- 229910000831 Steel Inorganic materials 0.000 title claims abstract description 42
- 239000010959 steel Substances 0.000 title claims abstract description 42
- 238000000034 method Methods 0.000 title claims abstract description 24
- 238000004519 manufacturing process Methods 0.000 title claims abstract description 20
- 229910001105 martensitic stainless steel Inorganic materials 0.000 title claims abstract description 20
- 239000003129 oil well Substances 0.000 title claims abstract description 16
- 238000005496 tempering Methods 0.000 claims abstract description 41
- 239000000203 mixture Substances 0.000 claims abstract description 28
- 238000010791 quenching Methods 0.000 claims abstract description 21
- 230000000171 quenching effect Effects 0.000 claims abstract description 21
- 239000012535 impurity Substances 0.000 claims abstract description 8
- 229910052750 molybdenum Inorganic materials 0.000 claims abstract description 7
- 229910052757 nitrogen Inorganic materials 0.000 claims abstract description 7
- 229910052804 chromium Inorganic materials 0.000 claims abstract description 6
- 229910052748 manganese Inorganic materials 0.000 claims abstract description 6
- 229910052717 sulfur Inorganic materials 0.000 claims abstract description 6
- 229910052721 tungsten Inorganic materials 0.000 claims abstract description 6
- 230000008569 process Effects 0.000 claims description 10
- 229910001220 stainless steel Inorganic materials 0.000 claims description 8
- 239000010935 stainless steel Substances 0.000 claims description 8
- 229910052735 hafnium Inorganic materials 0.000 claims description 7
- 229910052715 tantalum Inorganic materials 0.000 claims description 7
- 229910052726 zirconium Inorganic materials 0.000 claims description 7
- 238000010438 heat treatment Methods 0.000 abstract description 11
- 229910000734 martensite Inorganic materials 0.000 abstract description 9
- 229910052759 nickel Inorganic materials 0.000 abstract description 5
- 229910052698 phosphorus Inorganic materials 0.000 abstract description 5
- 229910052802 copper Inorganic materials 0.000 abstract description 3
- 229910052799 carbon Inorganic materials 0.000 abstract description 2
- 238000005260 corrosion Methods 0.000 description 36
- 230000007797 corrosion Effects 0.000 description 36
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 description 20
- 239000000463 material Substances 0.000 description 18
- 230000000694 effects Effects 0.000 description 17
- 230000008859 change Effects 0.000 description 15
- 239000003921 oil Substances 0.000 description 13
- 238000001816 cooling Methods 0.000 description 11
- 229910002092 carbon dioxide Inorganic materials 0.000 description 10
- 239000001569 carbon dioxide Substances 0.000 description 10
- 229910001566 austenite Inorganic materials 0.000 description 9
- 239000007858 starting material Substances 0.000 description 7
- 239000000460 chlorine Substances 0.000 description 6
- RWSOTUBLDIXVET-UHFFFAOYSA-N Dihydrogen sulfide Chemical compound S RWSOTUBLDIXVET-UHFFFAOYSA-N 0.000 description 4
- 230000015572 biosynthetic process Effects 0.000 description 4
- 239000007789 gas Substances 0.000 description 4
- 230000002829 reductive effect Effects 0.000 description 4
- 238000005336 cracking Methods 0.000 description 3
- 230000007423 decrease Effects 0.000 description 3
- 230000001681 protective effect Effects 0.000 description 3
- 230000009467 reduction Effects 0.000 description 3
- 230000009466 transformation Effects 0.000 description 3
- VEXZGXHMUGYJMC-UHFFFAOYSA-M Chloride anion Chemical compound [Cl-] VEXZGXHMUGYJMC-UHFFFAOYSA-M 0.000 description 2
- FAPWRFPIFSIZLT-UHFFFAOYSA-M Sodium chloride Chemical compound [Na+].[Cl-] FAPWRFPIFSIZLT-UHFFFAOYSA-M 0.000 description 2
- 230000009471 action Effects 0.000 description 2
- 230000002411 adverse Effects 0.000 description 2
- 239000007864 aqueous solution Substances 0.000 description 2
- 229910052801 chlorine Inorganic materials 0.000 description 2
- -1 chlorine ions Chemical class 0.000 description 2
- 238000009749 continuous casting Methods 0.000 description 2
- 230000006872 improvement Effects 0.000 description 2
- 238000002844 melting Methods 0.000 description 2
- 230000008018 melting Effects 0.000 description 2
- 238000005065 mining Methods 0.000 description 2
- 230000004044 response Effects 0.000 description 2
- 239000006104 solid solution Substances 0.000 description 2
- 230000006641 stabilisation Effects 0.000 description 2
- 238000011105 stabilization Methods 0.000 description 2
- 238000005728 strengthening Methods 0.000 description 2
- 238000009864 tensile test Methods 0.000 description 2
- 239000012085 test solution Substances 0.000 description 2
- 229910052720 vanadium Inorganic materials 0.000 description 2
- 101150113776 LMP1 gene Proteins 0.000 description 1
- 238000002441 X-ray diffraction Methods 0.000 description 1
- 239000008186 active pharmaceutical agent Substances 0.000 description 1
- 239000003795 chemical substances by application Substances 0.000 description 1
- 230000000052 comparative effect Effects 0.000 description 1
- 239000010779 crude oil Substances 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- 238000005553 drilling Methods 0.000 description 1
- 238000001192 hot extrusion Methods 0.000 description 1
- 229910000037 hydrogen sulfide Inorganic materials 0.000 description 1
- 238000007654 immersion Methods 0.000 description 1
- 238000009863 impact test Methods 0.000 description 1
- 229910052742 iron Inorganic materials 0.000 description 1
- 230000000670 limiting effect Effects 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- 238000003754 machining Methods 0.000 description 1
- 150000001247 metal acetylides Chemical class 0.000 description 1
- 125000000896 monocarboxylic acid group Chemical group 0.000 description 1
- 229910052758 niobium Inorganic materials 0.000 description 1
- 150000004767 nitrides Chemical class 0.000 description 1
- 229910052760 oxygen Inorganic materials 0.000 description 1
- 230000036961 partial effect Effects 0.000 description 1
- 238000005498 polishing Methods 0.000 description 1
- 238000001556 precipitation Methods 0.000 description 1
- 239000011253 protective coating Substances 0.000 description 1
- 238000003303 reheating Methods 0.000 description 1
- 230000000717 retained effect Effects 0.000 description 1
- 239000011780 sodium chloride Substances 0.000 description 1
- 238000009628 steelmaking Methods 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 230000007704 transition Effects 0.000 description 1
- 230000004580 weight loss Effects 0.000 description 1
- 229910000859 α-Fe Inorganic materials 0.000 description 1
Images
Landscapes
- Heat Treatment Of Articles (AREA)
Abstract
Description
本発明は、油井管用マルテンサイト系ステンレス継目無鋼管に係り、とくに、降伏強さYSが95ksi級(655〜758MPa)で、耐SSC性に優れた油井管用継目無鋼管の製造方法に関する。 The present invention relates to a martensitic stainless steel seamless pipe for oil well pipes, and more particularly to a method for producing a seamless steel pipe for oil well pipes having a yield strength YS of 95 ksi class (655 to 758 MPa) and excellent SSC resistance.
近年、原油価格の高騰や、近い将来に予想される石油資源の枯渇という観点から、従来、省みられなかったような深度が深い油田や、炭酸ガス、塩素イオン等を含む厳しい腐食環境の油田やガス田、さらには寒冷地や海底といった掘削環境が厳しい油田等の開発が盛んになっている。このような環境下で使用される油井用鋼管には、高強度で、かつ優れた耐食性、さらには優れた靭性を兼ね備えた材質を有することが要求される。 In recent years, from the viewpoint of soaring crude oil prices and the depletion of oil resources expected in the near future, oil fields with deeper depths that were not previously excluded, and oil fields with severe corrosive environments including carbon dioxide, chloride ions, etc. The development of oil fields and other harsh drilling environments such as cold regions and the seabed has become active. The oil well steel pipe used in such an environment is required to have a material having high strength, excellent corrosion resistance, and excellent toughness.
従来から、炭酸ガスCO2、塩素イオンCl−等を含む環境の油田、ガス田では、採掘に使用する油井管として13%Crマルテンサイト系ステンレス鋼管が多く使用されている。さらに最近では、炭酸ガスCO2、塩素イオンCl−に加えて、硫化水素H2Sを含む腐食環境が極めて厳しい油田等の開発が世界的規模で行われている。このような油田、ガス田の採掘に使用する油井管としては、高温下においても高強度で、しかも耐食性、耐応力腐食割れ性を兼ね備えた鋼管が要求される。 Conventionally, carbon dioxide CO 2, chloride ion Cl - oilfield environment and the like, in the gas field, the 13% Cr martensitic stainless steel pipes are widely used as oil country tubular goods for use in mining. More recently, development of oil fields and the like in which the corrosive environment containing hydrogen sulfide H 2 S in addition to carbon dioxide CO 2 and chlorine ions Cl − is extremely severe has been carried out on a global scale. As an oil well pipe used for mining such oil and gas fields, a steel pipe having high strength even at high temperatures and having both corrosion resistance and stress corrosion cracking resistance is required.
このような要求に対して、例えば特許文献1には、C:0.05mass%以下、Si:0.50mass%以下、Mn:0.30〜1.50mass%、P:0.03mass%以下、S:0.005mass%以下、Cr:11.0〜17.0mass%、Ni:3.0〜7.0mass%、Mo:0.5〜5.0mass%、Al:0.05mass%以下、N:0.01〜0.15mass%、O:0.005mass%以下を含み、かつNb:0.20mass%以下、V:0.20mass%以下のうちから選んだ少なくとも1種を含有し、残部は実質的にFeからなり、かつ次の3つの関係
0.8(Nb%)+(V%):0.02〜0.20、
(Cr%)+3.2(Mo%)+16(N%)+0.5(Ni%)−5(C%):17以上、
1.1{(Cr%)+1.5(Si%)+(Mo%)}−(Ni%)−0.5(Mn%)−30{(C%)+(N%)}:6以下、
を満足する、耐応力腐食割れ性および高温引張り特性に優れた油井管用高強度マルテンサイト系ステンレス鋼が提案されている。
In response to such a request, for example, in Patent Document 1, C: 0.05 mass% or less, Si: 0.50 mass% or less, Mn: 0.30 to 1.50 mass%, P: 0.03 mass% or less, S: 0.005 mass% or less , Cr: 11.0-17.0 mass%, Ni: 3.0-7.0 mass%, Mo: 0.5-5.0 mass%, Al: 0.05 mass% or less, N: 0.01-0.15 mass%, O: 0.005 mass% or less, and Contains at least one selected from Nb: 0.20 mass% or less, V: 0.20 mass% or less, with the balance being essentially Fe, and the following three relationships
0.8 (Nb%) + (V%): 0.02 to 0.20,
(Cr%) + 3.2 (Mo%) + 16 (N%) + 0.5 (Ni%) − 5 (C%): 17 or more,
1.1 {(Cr%) + 1.5 (Si%) + (Mo%)} − (Ni%) − 0.5 (Mn%) − 30 {(C%) + (N%)}: 6 or less,
A high-strength martensitic stainless steel for oil well pipes that satisfies the above requirements and has excellent stress corrosion cracking resistance and high-temperature tensile properties has been proposed.
また、特許文献2には、C:0.003〜0.050%、Si:0.05〜1.00%、Mn:0.10〜1.50%、Cr:10.5〜14.0%、Ni:1.5〜7.0%、V:0.02〜0.20%、N:0.003〜0.070%、およびTi:0.300%以下を含み、残部は実質的にFeからなり、不純物としてのPが0.035%以下、Sが0.010%以下であり、かつ{[Ti]−3.4[N]}/[C]> 4.5を満足する組成の鋼材を850〜950℃に加熱し焼入れした後、焼戻温度Tが鋼材のAc1点±35℃の範囲内の温度で、軟化特性値LMP1(=T(20+1.7log(t))×10−3)のばらつきΔLMP1が0.5以下となる条件で焼戻すことを特徴とするマルテンサイト系ステンレス鋼の製造方法が記載されている。特許文献2に記載された技術によれば、化学組成の調整とともに、適切な温度で焼入れを行うことにより、焼戻軟化曲線の傾きが急峻な傾きとなることが防止でき、さらに厳密な焼戻条件の制御により、マルテンサイト系ステンレス鋼の耐力のばらつきを小さく抑えることができるとしている。 In Patent Document 2, C: 0.003 to 0.050%, Si: 0.05 to 1.00%, Mn: 0.10 to 1.50%, Cr: 10.5 to 14.0%, Ni: 1.5 to 7.0%, V: 0.02 to 0.20%, N: 0.003 to 0.070%, and Ti: 0.300% or less, the balance being substantially made of Fe, P as an impurity is 0.035% or less, S is 0.010% or less, and {[Ti] -3.4 [ N]} / [C]> After heating and quenching a steel material having a composition satisfying 4.5 to 850 to 950 ° C., the tempering temperature T is within the range of Ac1 point ± 35 ° C. of the steel material, and the softening characteristic value LMP1 There is described a method for producing martensitic stainless steel characterized by tempering under the condition that the variation ΔLMP1 of (= T (20 + 1.7log (t)) × 10 −3 ) is 0.5 or less. According to the technique described in Patent Document 2, by adjusting the chemical composition and quenching at an appropriate temperature, it is possible to prevent the temper softening curve from becoming a steep slope, and more rigorous tempering. By controlling the conditions, it is said that variations in the proof stress of martensitic stainless steel can be kept small.
最近、開発される油田では、炭酸ガスCO2、塩素イオンCl−に加えて、硫化水素H2Sを含む腐食環境の油田が増加し、しかも経年変化による、含まれる硫化水素H2S濃度の増加が懸念されている。このため、使用する油井管用材料に対して、耐SSC性の向上が重視されるようになり、油井管用材料に対し硬さの低減が厳しく要求されるようになってきた。たとえば、YS95ksi級(655〜758MPa)の鋼管では、HRCで27未満という硬さ上限の規定を満足することが要求されている。 Recently, in the oil fields to be developed, oil fields with corrosive environments containing hydrogen sulfide H 2 S in addition to carbon dioxide CO 2 and chlorine ions Cl − have increased, and the concentration of hydrogen sulfide H 2 S contained due to secular change has increased. There is concern about the increase. For this reason, improvement in SSC resistance has been emphasized with respect to the oil well pipe material to be used, and a reduction in hardness has been strictly demanded for the oil well pipe material. For example, a steel pipe of YS95ksi class (655 to 758 MPa) is required to satisfy the hardness upper limit of less than 27 in HRC.
しかし、このような要求に対し、特許文献1に記載された技術では、焼戻し時の降伏強さの変化が大きく、最適焼戻温度範囲が狭いため、安定して所望の降伏強さを確保することが難しく、さらに所望の低硬さを兼備させることが難しいという問題があった。また、特許文献2に記載された技術によれば、降伏強さのばらつきが小さいマルテンサイト系ステンレス鋼管の製造が可能であるが、さらなる強度の安定化が要求されていた。 However, in response to such a request, the technique described in Patent Document 1 has a large change in yield strength during tempering, and the optimum tempering temperature range is narrow, so that the desired yield strength can be secured stably. In addition, there is a problem that it is difficult to combine desired low hardness. Further, according to the technique described in Patent Document 2, it is possible to manufacture a martensitic stainless steel pipe with a small variation in yield strength, but further strength stabilization has been required.
本発明は、かかる従来技術の問題を解決し、降伏強さYS95ksi級の高降伏強さを有し、さらにHRCで27未満という低硬さを兼備した、耐SSC性に優れた油井管用マルテンサイト系ステンレス鋼管を安定して製造する方法を提供することを目的とする。 The present invention solves such problems of the prior art, has a high yield strength of YS95ksi class, and has a low hardness of less than 27 in HRC, and has excellent SSC resistance and is excellent in martensite for oil well pipes. An object of the present invention is to provide a method for stably producing a stainless steel pipe.
従来成分組成(質量%で、0.03%C−0.20%Si−0.65%Mn−13%Cr−5.5%Ni−2%Mo−0.01%V−0.05%Nを含む組成)の13Crマルテンサイト系ステンレス鋼管を、950℃に加熱し焼入れしたのち、550〜680℃の各温度で焼戻した場合の強度変化を図1に示す。図1から、従来成分組成では、YS:95ksi級のYS範囲とするためには、焼戻温度を狭い温度範囲に調整する必要が有ること、しかもHRC27未満の低硬さとすることは困難であること、がわかる。 13Cr martensitic stainless steel pipe of conventional composition (composition containing 0.03% C-0.20% Si-0.65% Mn-13% Cr-5.5% Ni-2% Mo-0.01% V-0.05% N) FIG. 1 shows the change in strength when the steel was tempered by heating to 950 ° C. and then tempered at each temperature of 550 to 680 ° C. From FIG. 1, it is necessary to adjust the tempering temperature to a narrow temperature range in the conventional component composition in order to make the YS range of YS: 95 ksi class, and it is difficult to make the hardness less than HRC27. I understand that.
そこで、本発明者らは、上記した目的を達成するために、13Crマルテンサイト系ステンレス鋼管の焼戻特性におよぼす成分組成、焼入れ条件の影響について、鋭意研究した。その結果、まず所望の低硬さとするためには、0.015質量%以下という極低C量としたうえでさらに、0.03質量%以上のTiを含有する成分系として、更なる固溶C量の低減を図ることが必要であることに想到した。そしてさらに、極低C−Ti系としたうえで、焼入れ加熱温度を750〜840℃と低温化することにより、焼戻温度に対する降伏応力の変化が小さくなることを新規に見出した。この理由について、本発明者らは以下のように考えた。 Therefore, in order to achieve the above-mentioned object, the present inventors diligently studied the influence of the component composition and quenching conditions on the tempering characteristics of 13Cr martensitic stainless steel pipe. As a result, in order to achieve the desired low hardness first, the amount of C is as low as 0.015% by mass or less, and further, as a component system containing 0.03% by mass or more of Ti, further reduction of the amount of solid solution C is achieved. I realized that it was necessary to plan. Furthermore, the present inventors have newly found that the yield stress change with respect to the tempering temperature becomes small by reducing the quenching heating temperature to 750 to 840 ° C. after making it an extremely low C-Ti system. The present inventors considered the reason as follows.
焼入れ加熱温度を上記したように低温化することにより、形成されるオーステナイトは非常に微細なものとなる。非常に微細なオーステナイトを焼入れして得られるマルテンサイトも非常に微細なものとなる。このような非常に微細なマルテンサイト組織は、多数の変態開始サイトを有していることになり、再加熱時に早い段階からオーステナイトへの変態が開始することになる。すなわち実質的にAc1変態点が低下したことになる。このことにより、焼戻時に、焼戻温度の変化に対する析出オーステナイト量の変化が小さく、したがって、焼戻後の降伏強さの変化が小さくなる。焼戻温度に対する降伏応力の変化が小さくなることにより、所望範囲の降伏強さを有する鋼管を安定して製造できることになる。 By lowering the quenching heating temperature as described above, the formed austenite becomes very fine. The martensite obtained by quenching very fine austenite also becomes very fine. Such a very fine martensite structure has a large number of transformation start sites, and transformation to austenite starts at an early stage during reheating. That is, the Ac1 transformation point is substantially lowered. This reduces the change in the amount of precipitated austenite with respect to the change in tempering temperature during tempering, and thus reduces the change in yield strength after tempering. By reducing the change in the yield stress with respect to the tempering temperature, a steel pipe having a desired range of yield strength can be manufactured stably.
本発明は、かかる知見に基づき、さらに検討を加えて完成されたものである。すなわち、本発明の要旨は次のとおりである。
(1)質量%で、C:0.015%以下、Si:1.0%以下、Mn:2.0%以下、P:0.020%以下、S:0.010%以下、Al:0.01〜0.10%、Cr:10〜14%、Ni:3〜8%以下、Ti:0.03〜0.15%、N:0.015%以下を含み、さらに、Cu:1〜4%、Mo:1〜4%、W:1〜4%、Co:1〜4%のうちから選ばれた1種または2種以上を含有し、残部Feおよび不可避的不純物からなる組成を有するステンレス継目無鋼管に、750〜840℃の範囲の温度に加熱したのち焼入れする焼入れ処理と、650℃以下の温度で焼き戻す焼戻処理と、を施し、YS95ksi級の高降伏強さとロックウェルC硬さHRC27未満の低硬さとを兼備し、耐SSC性に優れるステンレス継目無鋼管とすることを特徴とする油井管用マルテンサイト系ステンレス継目無鋼管の製造方法。
(2)(1)において、前記組成に加えてさらに、質量%で、Nb:0.10%以下、Zr:0.10%以下、Hf:0.10%以下、Ta:0.10%以下のうちから選ばれた1種または2種以上を含有する組成とすることを特徴とする油井管用マルテンサイト系ステンレス継目無鋼管の製造方法。
(3)(1)または(2)において、前記組成に加えてさらに、質量%で、Ca:0.010%以下、REM:0.010%以下、Mg:0.010%以下、B:0.010%以下のうちから選ばれた1種または2種以上を含有する組成とすることを特徴とする油井管用マルテンサイト系ステンレス継目無鋼管の製造方法。
The present invention has been completed based on such findings and further studies. That is, the gist of the present invention is as follows.
(1) By mass%, C: 0.015% or less, Si: 1.0% or less, Mn: 2.0% or less, P: 0.020% or less, S: 0.010% or less, Al: 0.01-0.10%, Cr: 10-14% Ni: 3 to 8% or less, Ti: 0.03 to 0.15%, N: 0.015% or less, Cu: 1 to 4%, Mo: 1 to 4%, W: 1 to 4%, Co: 1 It hardens after heating to the temperature of the range of 750-840 degreeC to the stainless steel seamless steel pipe which contains the 1 type (s) or 2 types or more chosen from -4%, and has the composition which consists of remainder Fe and an unavoidable impurity. A stainless steel with excellent SSC resistance, with quenching treatment and tempering treatment tempering at a temperature of 650 ° C or less, combined with high yield strength of YS95ksi class and low hardness of Rockwell C hardness less than HRC27. The manufacturing method of the martensitic stainless steel seamless pipe for oil country tubular goods characterized by using a steel pipe.
(2) In (1), in addition to the above composition, in addition to mass, Nb: 0.10% or less, Zr: 0.10% or less, Hf: 0.10% or less, Ta: 0.10% or less Or the manufacturing method of the martensitic stainless steel seamless pipe for oil country tubular goods characterized by setting it as the composition containing 2 or more types.
(3) In (1) or (2), in addition to the above-mentioned composition, in mass%, Ca: 0.010% or less, REM: 0.010% or less, Mg: 0.010% or less, B: 0.010% or less The manufacturing method of the martensitic stainless steel seamless pipe for oil country pipes characterized by setting it as the composition containing 1 type, or 2 or more types.
本発明によれば、焼戻し時の降伏強さの変化が小さくなり、狭い適正焼戻温度範囲でも、安定して降伏強さ95ksi級の高強度を確保でき、かつHRC27未満の低硬さをも兼備できるという耐SSC性に優れた油井管用マルテンサイト系ステンレス継目無鋼管を安定して製造でき、産業上格段の効果を奏する。 According to the present invention, the change in yield strength at the time of tempering is reduced, and a high strength of a yield strength of 95 ksi can be secured stably even in a narrow appropriate tempering temperature range, and a low hardness of less than HRC27 is also achieved. The martensitic stainless steel seamless pipe for oil well pipes with excellent SSC resistance that can be used in combination can be manufactured stably, and has a remarkable industrial effect.
まず、本発明で、出発素材とするステンレス継目無鋼管の組成限定の理由について説明する。なお、以下、とくに断らないかぎり質量%は単に%と記す。
本発明では、C:0.015%以下、Si:1.0%以下、Mn:2.0%以下、P:0.020%以下、S:0.010%以下、Al:0.01〜0.10%、Cr:10〜14%、Ni:3〜8%、Ti:0.03〜0.15%、N:0.015%以下を含み、さらに、Cu:1〜4%、Mo:1〜4%、W:1〜4%、Co:1〜4%のうちから選ばれた1種または2種以上を含有し、残部Feおよび不可避的不純物からなる組成を有するステンレス継目無鋼管を出発素材とする。
First, the reason for limiting the composition of a stainless steel seamless steel pipe as a starting material in the present invention will be described. Hereinafter, unless otherwise specified, mass% is simply referred to as%.
In the present invention, C: 0.015% or less, Si: 1.0% or less, Mn: 2.0% or less, P: 0.020% or less, S: 0.010% or less, Al: 0.01-0.10%, Cr: 10-14%, Ni: 3-8%, Ti: 0.03-0.15%, N: 0.015% or less, further Cu: 1-4%, Mo: 1-4%, W: 1-4%, Co: 1-4% A stainless steel seamless steel pipe having a composition comprising one or more selected from among them and the balance of Fe and inevitable impurities is used as a starting material.
C:0.015%以下
Cは、マルテンサイト系ステンレス鋼の強度に関係する重要な元素であり、所望の高強度を確保するためには、0.003%以上含有することが望ましいが、0.015%を超える含有は、所望の低硬さを実現できなくなるとともに、靭性、さらには耐食性が低下しやすくなる。このため、本発明では、Cは0.015%以下に限定した。なお、好ましくは0.010%以下である。
C: 0.015% or less C is an important element related to the strength of martensitic stainless steel. To ensure the desired high strength, 0.003% or more is desirable, but more than 0.015% The desired low hardness cannot be realized, and the toughness and further the corrosion resistance are liable to be lowered. For this reason, in the present invention, C is limited to 0.015% or less. In addition, Preferably it is 0.010% or less.
Si:1.0%以下
Siは、通常の製鋼過程において脱酸剤として作用する元素であり、本発明では、0.05%以上含有させることが望ましいが、1.0%を超えて含有すると、靭性が低下し、さらに冷間加工性も低下する。このために、Siは1.0%以下に限定した。なお、好ましくは、安定した強度確保の観点から0.10〜0.30%である。
Si: 1.0% or less
Si is an element that acts as a deoxidizing agent in the normal steelmaking process. In the present invention, it is desirable to contain 0.05% or more, but if it exceeds 1.0%, the toughness is lowered, and cold workability is further reduced. Also decreases. For this reason, Si was limited to 1.0% or less. In addition, Preferably, it is 0.10 to 0.30% from a viewpoint of ensuring stable strength.
Mn:2.0%以下
Mnは、強度を増加させる元素であり、本発明では油井管用鋼管として必要な強度を確保するために0.1%以上含有することが望ましいが、2.0%を超える含有は、靭性に悪影響を及ぼす。このため、Mnは2.0%以下に限定した。なお、好ましくは0.3〜0.8%である。
P:0.020%以下
Pは、耐炭酸ガス腐食性等の耐食性を劣化させる元素であり、この発明では可及的に低減することが望ましいが、極端な低減は製造コストの上昇を招く。工業的に比較的安価に実施可能でかつ耐炭酸ガス腐食性等の耐食性を劣化させない範囲として、Pは0.020%以下に限定した。なお、好ましくは0.015%以下である。
Mn: 2.0% or less
Mn is an element that increases the strength. In the present invention, Mn is desirably contained in an amount of 0.1% or more in order to ensure the strength required as a steel pipe for oil country tubular goods. However, the content exceeding 2.0% adversely affects toughness. For this reason, Mn was limited to 2.0% or less. In addition, Preferably it is 0.3 to 0.8%.
P: 0.020% or less P is an element that deteriorates corrosion resistance such as carbon dioxide corrosion resistance. In this invention, it is desirable to reduce it as much as possible, but extreme reduction leads to an increase in manufacturing cost. P is limited to 0.020% or less as a range that can be industrially implemented at a relatively low cost and does not deteriorate the corrosion resistance such as carbon dioxide corrosion resistance. In addition, Preferably it is 0.015% or less.
S:0.010%以下
Sは、パイプ製造過程において熱間加工性を著しく劣化させる元素であり、可及的に少ないことが望ましいが、0.010%以下に低減すれば通常工程でのパイプ製造が可能となることから、Sは0.010%以下に限定した。なお、好ましくは0.002%以下である。
Al:0.01〜0.10%
Alは、強力な脱酸作用を有する元素であり、このような効果を得るためには、0.01%以上の含有を必要とするが、0.10%を超える含有は、靭性に悪影響を及ぼす。このため、Alは0.01〜0.10%に限定した。なお、好ましくは0.04%以下である。
S: 0.010% or less S is an element that significantly deteriorates hot workability in the pipe manufacturing process, and it is desirable that it be as small as possible, but if it is reduced to 0.010% or less, pipes can be manufactured in the normal process. Therefore, S is limited to 0.010% or less. In addition, Preferably it is 0.002% or less.
Al: 0.01-0.10%
Al is an element having a strong deoxidizing action, and in order to obtain such an effect, the content of 0.01% or more is required, but the content exceeding 0.10% adversely affects toughness. For this reason, Al was limited to 0.01 to 0.10%. In addition, Preferably it is 0.04% or less.
Cr:10〜14%
Crは、保護被膜を形成して耐食性を向上させる元素で、とくに耐炭酸ガス腐食性、耐炭酸ガス応力腐食割れ性、耐SSC性等の向上に有効に寄与する元素である。Crを10%以上含有すれば、油井管用として必要な耐食性を確保できることから、本発明では10%をCr含有量の下限とした。一方、14%を超える多量の含有は、フェライトの生成が容易となり、マルテンサイト相の安定確保または熱間加工性の低下防止のために、多量の高価なオーステナイト生成元素の添加を必要とし経済的に不利となる。このため、Crは10〜14%の範囲に限定した。なお、好ましくは、所望の耐食性と焼戻後の強度安定化や熱間加工性の確保という観点から11.5〜13.5%である。
Cr: 10-14%
Cr is an element that improves the corrosion resistance by forming a protective film, and is an element that contributes effectively to the improvement of carbon dioxide gas corrosion resistance, carbon dioxide stress corrosion cracking resistance, SSC resistance, and the like. If Cr is contained in an amount of 10% or more, the corrosion resistance necessary for oil well pipes can be ensured. Therefore, in the present invention, 10% is set as the lower limit of the Cr content. On the other hand, a large content exceeding 14% facilitates the formation of ferrite, and requires the addition of a large amount of expensive austenite-generating elements to ensure the stability of the martensite phase or prevent the hot workability from decreasing. Disadvantageous. For this reason, Cr was limited to the range of 10 to 14%. Preferably, it is 11.5 to 13.5% from the viewpoint of desired corrosion resistance, strength stabilization after tempering and ensuring hot workability.
Ni:3〜8%
Niは、保護被膜を強固にする作用を有し、耐炭酸ガス腐食性等の耐食性を高めるとともに靭性をも向上させる元素である。このような効果を得るためには、3%以上の含有を必要とするが、8%を超える含有は、オーステナイト相を安定化させ、マルテンサイト相の形成を困難とし、安定した組織形成を妨げるとともに、製造コストの高騰を招く。このため、Niは3〜8%以下の範囲に限定した。なお、好ましくは5〜7%である。
Ni: 3-8%
Ni is an element that has an effect of strengthening the protective coating, and improves corrosion resistance such as carbon dioxide corrosion resistance and also improves toughness. In order to obtain such an effect, the content of 3% or more is required. However, the content exceeding 8% stabilizes the austenite phase, makes it difficult to form a martensite phase, and prevents stable structure formation. At the same time, the manufacturing cost increases. For this reason, Ni was limited to the range of 3 to 8% or less. In addition, Preferably it is 5 to 7%.
Ti:0.03〜0.15%
Tiは、本発明では重要な元素であり、Cと結合しTi炭化物を形成し、固溶Cを減少させ、極低C化とともに、所望の低硬さを実現させる本発明では重要な元素であり、このような効果を得るためには0.03%以上の含有を必要とする。一方、0.15%を超える含有は、靭性を低下させる。このため、Tiは0.03〜0.15%の範囲に限定した。なお、好ましくは0.06〜0.10%である。
Ti: 0.03-0.15%
Ti is an important element in the present invention, and combines with C to form Ti carbide, thereby reducing solid solution C, achieving an extremely low C and realizing a desired low hardness. In order to obtain such an effect, a content of 0.03% or more is required. On the other hand, the content exceeding 0.15% lowers toughness. For this reason, Ti was limited to the range of 0.03-0.15%. In addition, Preferably it is 0.06-0.10%.
N:0.015%以下
Nは、耐孔食性を向上させる作用を有するとともに、鋼中に固溶し、Cと同様に強度を増加させる作用を有する元素である。また、Nは、Tiと結合しTi窒化物を形成し、低硬さ化に有効に作用する有効Ti量を低減する。このため、本発明では、Nはできるだけ低減することが望ましい。0.015%を超えて含有すると、所望の低硬さを達成できなくなるため、本発明では、Nは0.015%以下に限定した。なお、好ましくは0.010%以下である。
N: 0.015% or less N is an element that has the effect of improving the pitting corrosion resistance and also has the effect of increasing the strength in the same manner as C by being dissolved in steel. Further, N combines with Ti to form Ti nitride, and reduces the effective Ti amount that effectively acts to reduce the hardness. For this reason, in the present invention, it is desirable to reduce N as much as possible. If the content exceeds 0.015%, the desired low hardness cannot be achieved. Therefore, in the present invention, N is limited to 0.015% or less. In addition, Preferably it is 0.010% or less.
Cu:1〜4%、Mo:1〜4%、W:1〜4%、Co:1〜4%のうちから選ばれた1種または2種以上
Cu、Mo、W、Coはいずれも、耐食性を向上させる作用を有する元素であり、必要に応じて選択して含有する。
Cuは、保護皮膜を強固にして耐孔食性を向上させる作用を有し、耐食性向上に有効に作用する元素であり、このような効果を得るためには、1%以上含有することが望ましい。一方、4%を超える含有は、一部が析出して靭性を低下させる。このため、含有する場合には、Cuは、1〜4%に限定した。なお、好ましくは1〜2%である。
One or more selected from Cu: 1-4%, Mo: 1-4%, W: 1-4%, Co: 1-4%
Cu, Mo, W, and Co are all elements that have an action of improving corrosion resistance, and are selected and contained as necessary.
Cu is an element that has a function of strengthening the protective film and improving the pitting corrosion resistance, and effectively acts to improve the corrosion resistance. In order to obtain such an effect, it is desirable to contain 1% or more. On the other hand, if the content exceeds 4%, a part of it is precipitated and the toughness is lowered. For this reason, when it contained, Cu was limited to 1-4%. In addition, Preferably it is 1-2%.
また、Moは、Cl−による孔食に対する抵抗性を増加させる作用を有し、耐食性向上に有効に作用する元素であり、このような効果を得るためには、1%以上含有することが望ましい。一方、4%を超えて含有すると、靭性が低下するとともに、材料コストを高騰させる。このため、含有する場合には、Moは1〜4%に限定した。なお、好ましくは1〜3%である。 Mo is an element that has an effect of increasing resistance to pitting corrosion caused by Cl − and effectively acts to improve corrosion resistance. In order to obtain such an effect, Mo is preferably contained in an amount of 1% or more. . On the other hand, when it contains exceeding 4%, toughness will fall and material cost will be raised. For this reason, when it contained, Mo was limited to 1-4%. In addition, Preferably it is 1-3%.
Wは孔食に対する抵抗性を増加させ、耐食性向上に有効に作用する元素であり、このような効果を得るためには、1%以上含有することが望ましい。一方、4%を超えて含有すると、靭性が低下するとともに、材料コストを高騰させる。このため、含有する場合には、Wは1〜4%に限定した。なお、好ましくは1〜2%である。
Coは、保護膜を強固にして耐孔食性向上に有効に作用する元素であり、このような効果を得るためには、1%以上含有することが望ましい。一方、4%を超えて含有すると、靭性が低下するとともに、材料コストを高騰させる。このため、含有する場合には、Coは1〜4%に限定した。なお、好ましくは1〜2%である。
W is an element that increases resistance to pitting corrosion and effectively acts to improve corrosion resistance. In order to obtain such an effect, W is desirably contained in an amount of 1% or more. On the other hand, when it contains exceeding 4%, toughness will fall and material cost will be raised. For this reason, when it contained, W was limited to 1-4%. In addition, Preferably it is 1-2%.
Co is an element that strengthens the protective film and effectively acts to improve pitting corrosion resistance. In order to obtain such an effect, it is desirable to contain 1% or more. On the other hand, when it contains exceeding 4%, toughness will fall and material cost will be raised. For this reason, when it contained, Co was limited to 1-4%. In addition, Preferably it is 1-2%.
上記した成分が基本の成分であるが、これら基本の組成に加えてさらに、選択元素として、Nb:0.10%以下、Zr:0.10%以下、Hf:0.10%以下、Ta:0.10%以下のうちから選ばれた1種または2種以上、および/または、Ca:0.010%以下、REM:0.010%以下、Mg:0.010%以下、B:0.010%以下のうちから選ばれた1種または2種以上、を含有できる。
Nb:0.10%以下、Zr:0.10%以下、Hf:0.10%以下、Ta:0.10%以下のうちから選ばれた1種または2種以上
Nb、Zr、Hf、Taは、いずれも炭化物を形成し、鋼の強度を増加させる作用を有する元素であり、必要に応じて選択して1種または2種以上を含有できる。
The above-mentioned components are basic components. In addition to these basic compositions, Nb: 0.10% or less, Zr: 0.10% or less, Hf: 0.10% or less, Ta: 0.10% or less as a selective element One or more selected, and / or Ca: not more than 0.010%, REM: not more than 0.010%, Mg: not more than 0.010%, B: not more than 0.010%, Can be contained.
One or more selected from Nb: 0.10% or less, Zr: 0.10% or less, Hf: 0.10% or less, Ta: 0.10% or less
Nb, Zr, Hf, and Ta are all elements that have the effect of forming carbides and increasing the strength of steel, and can be selected as necessary to contain one or more.
このような効果を得るためには、Nb:0.01%以上、Zr:0.01%以上、Hf:0.01%以上、Ta:0.01%以上、含有することが望ましい。一方、Nb:0.10%、Zr:0.10%、Hf:0.10%、Ta:0.10%を超えて含有すると、靱性が低下する。このため、含有する場合には、Nb:0.10%以下、Zr:0.10%以下、Hf:0.10%以下、Ta:0.10%以下にそれぞれ限定することが好ましい。 In order to obtain such effects, it is desirable to contain Nb: 0.01% or more, Zr: 0.01% or more, Hf: 0.01% or more, Ta: 0.01% or more. On the other hand, when Nb: 0.10%, Zr: 0.10%, Hf: 0.10% and Ta: 0.10% are contained, the toughness decreases. For this reason, when it contains, it is preferable to limit to Nb: 0.10% or less, Zr: 0.10% or less, Hf: 0.10% or less, Ta: 0.10% or less, respectively.
Ca:0.010%以下、REM:0.010%以下、Mg:0.010%以下、B:0.010%以下のうちから選ばれた1種または2種以上
Ca、REM、Mg、Bはいずれも、介在物の形状制御を介し、耐食性、とくに耐SSC性を向上させる作用を有する元素であり、必要に応じて1種または2種以上を選択し含有できる。このような効果を得るためには、Ca:0.0005%以上、REM:0.0005%以上、Mg:0.0005%以上、B:0.0005%以上含有することが望ましいが、Ca:0.010%、REM:0.010%、Mg:0.010%、B:0.010%をそれぞれ超える含有は、靭性、耐炭酸ガス腐食性を低下させる。このため、含有する場合には、Ca:0.010%以下、REM:0.010%以下、Mg:0.010%以下、B:0.010%以下にそれぞれ限定することが好ましい。
One or more selected from Ca: 0.010% or less, REM: 0.010% or less, Mg: 0.010% or less, B: 0.010% or less
Ca, REM, Mg, and B are all elements that have the effect of improving the corrosion resistance, particularly SSC resistance, through the shape control of inclusions, and one or more elements can be selected and contained as necessary. . In order to obtain such an effect, it is desirable to contain Ca: 0.0005% or more, REM: 0.0005% or more, Mg: 0.0005% or more, B: 0.0005% or more, but Ca: 0.010%, REM: 0.010%, Inclusions exceeding Mg: 0.010% and B: 0.010% lower toughness and carbon dioxide corrosion resistance. For this reason, when it contains, it is preferable to limit to Ca: 0.010% or less, REM: 0.010% or less, Mg: 0.010% or less, B: 0.010% or less, respectively.
上記した成分以外の残部は、Feおよび不可避的不純物からなる。不可避的不純物としては、V:0.03%以下、O:0.010%以下に調整することが望ましい。なお、不純物としてのVが0.03%を超えて多量に含有されると、著しく強度が増加し、安定して所望の高降伏強さと、所望の低硬さとを確保できなくなる。このため、Vは0.03%以下にすることが望ましい。なお、より好ましくは0.01%以下である。 The balance other than the components described above consists of Fe and inevitable impurities. As unavoidable impurities, it is desirable to adjust to V: 0.03% or less and O: 0.010% or less. If V as an impurity is contained in a large amount exceeding 0.03%, the strength is remarkably increased, and a desired high yield strength and a desired low hardness cannot be secured stably. For this reason, it is desirable that V be 0.03% or less. In addition, More preferably, it is 0.01% or less.
本発明では、上記した組成を有するステンレス継目無鋼管を出発素材として、焼入れ処理と焼戻処理とを施す。
本発明では、上記した組成を有する出発素材の製造方法はとくに限定する必要はないが、上記した組成を有する溶鋼を、転炉、電気炉、真空溶解炉等の通常公知の溶製方法で溶製し、連続鋳造法、造塊−分塊圧延法等、通常の方法でビレット等の鋼管素材とすることが好ましい。ついで、これら鋼管素材を加熱し、通常のマンネスマン−プラグミル方式、あるいはマンネスマン−マンドレルミル方式の製造工程を用いて熱間加工し造管して、所望寸法の継目無鋼管とし、出発素材とすることが好ましい。なお、プレス方式による熱間押出で継目無鋼管を製造してもよい。また、造管後、継目無鋼管は、空冷以上の冷却速度で室温まで冷却することが好ましい。
In the present invention, a stainless steel seamless steel pipe having the above-described composition is used as a starting material, and a quenching process and a tempering process are performed.
In the present invention, the production method of the starting material having the above composition is not particularly limited, but the molten steel having the above composition is melted by a generally known melting method such as a converter, an electric furnace, a vacuum melting furnace or the like. It is preferable to produce a steel pipe material such as billet by a usual method such as manufacturing, continuous casting method, ingot-making-slabbing method. Next, these steel pipe materials are heated and hot-worked and piped using a normal Mannesmann-plug mill method or Mannesmann-Mandrel mill manufacturing process to produce seamless steel pipes of the desired dimensions, and used as starting materials. Is preferred. In addition, you may manufacture a seamless steel pipe by the hot extrusion by a press system. Moreover, it is preferable that a seamless steel pipe is cooled to room temperature at a cooling rate equal to or higher than air cooling after pipe making.
出発素材(継目無鋼管)は、まず、焼入れ処理を施される。
本発明における焼入れ処理は、750〜840℃の範囲の温度に加熱したのち焼入れする処理とする。この範囲内の温度に加熱し、焼入れすることにより、微細なマルテンサイト相が形成され、焼戻処理時に、急激なγの形成が抑制されて、形成するγ量を適正範囲内に調整することが容易となるとともに、Ti炭化物の析出を促進する。このため、焼戻温度変化に伴う降伏強さの変化(低下)が小さく、安定して所望の降伏強さ、および所望の低硬さを確保することが可能となる。焼入れの加熱温度が、750℃未満では、完全なオーステナイト化が達成できず、焼戻後に所望の降伏強さを確保できなくなる。一方、840℃を超えると、オーステナイト粒が粗大となり、その後の焼戻処理で、急激なオーステナイト形成が生じるため、オーステナイト量の調整が難しくなる。その結果、降伏強さのばらつきが生じ、所望の降伏強さを安定して確保できなくなる。なお、焼入れ時の冷却は、加熱温度から空冷またはそれ以上の冷却速度で100℃以下の温度域まで冷却することが好ましい。本発明における出発素材は焼入れ性が高いため、空冷程度の冷却速度で100℃以下の温度域まで冷却すれば、十分な焼入れ組織(マルテンサイト組織)を得ることができる。また、焼入れ温度における保持時間は、10min以上とすることが組織の均一化の観点から好ましい。
The starting material (seamless steel pipe) is first quenched.
The quenching process in the present invention is a process of quenching after heating to a temperature in the range of 750 to 840 ° C. By heating to a temperature within this range and quenching, a fine martensite phase is formed, and during the tempering process, rapid γ formation is suppressed, and the amount of γ to be formed is adjusted within the appropriate range. Facilitates the precipitation of Ti carbide. For this reason, the change (decrease) in the yield strength accompanying the change in the tempering temperature is small, and it becomes possible to stably secure the desired yield strength and the desired low hardness. If the heating temperature for quenching is less than 750 ° C., complete austenite cannot be achieved, and a desired yield strength cannot be ensured after tempering. On the other hand, when the temperature exceeds 840 ° C., the austenite grains become coarse, and abrupt austenite formation occurs in the subsequent tempering treatment, making it difficult to adjust the amount of austenite. As a result, the yield strength varies, and the desired yield strength cannot be secured stably. The cooling at the time of quenching is preferably performed from the heating temperature to a temperature range of 100 ° C. or lower at a cooling rate of air cooling or higher. Since the starting material in the present invention has high hardenability, a sufficient quenched structure (martensitic structure) can be obtained by cooling to a temperature range of 100 ° C. or lower at a cooling rate of about air cooling. The holding time at the quenching temperature is preferably 10 min or more from the viewpoint of homogenizing the structure.
焼入れ処理を施された継目無鋼管は、引続き、焼戻処理を施される。焼戻処理の加熱温度(焼戻温度)は、650℃以下好ましくは550℃以上の温度とする。本発明では焼戻温度は、所望の降伏強さが確保できるように、組成に応じて適正な温度を選択することが肝要となる。焼戻温度が650℃を超えて高温となると、形成されるγ量が増大し、所望の降伏強さを確保できなくなる。また、550℃未満では、焼戻効果が期待できず、所望の降伏強さを確保できなくなる。本発明では焼戻温度は、所望の降伏強さが確保できるように、上記した温度範囲で、組成に応じて適正な温度を選択することが肝要となる。なお、焼戻温度での保持時間は20min以上とすることが強度ばらつきを防止する観点から好ましい。焼戻処理では、上記した焼戻温度で所定時間保持した後、好ましくは空冷以上の冷却速度で、冷却する。 The seamless steel pipe that has been subjected to the quenching process is subsequently subjected to a tempering process. The heating temperature (tempering temperature) in the tempering treatment is 650 ° C. or lower, preferably 550 ° C. or higher. In the present invention, it is important to select an appropriate tempering temperature according to the composition so that a desired yield strength can be secured. When the tempering temperature is higher than 650 ° C., the amount of γ formed increases, and the desired yield strength cannot be ensured. If the temperature is lower than 550 ° C., the tempering effect cannot be expected, and the desired yield strength cannot be ensured. In the present invention, it is important to select an appropriate tempering temperature in accordance with the composition within the above-described temperature range so that a desired yield strength can be ensured. The holding time at the tempering temperature is preferably 20 minutes or more from the viewpoint of preventing strength variation. In the tempering process, after holding for a predetermined time at the above-described tempering temperature, cooling is preferably performed at a cooling rate equal to or higher than air cooling.
上記した製造方法で得られる継目無鋼管は、上記した組成と、焼戻マルテンサイト相を主体とし、残留γ相が面積率で5〜25%、好ましくは10〜15%、含有する組織とを有し、95ksi級(655〜758MPa)の降伏強さと、HRCで27未満の低硬さとを兼備する、耐SSC性に優れた油井管用マルテンサイト系ステンレス継目無鋼管である。
以下、さらに実施例に基づいて、本発明を説明する。
The seamless steel pipe obtained by the manufacturing method described above has the above-described composition, and a structure containing mainly a tempered martensite phase and a residual γ phase in an area ratio of 5 to 25%, preferably 10 to 15%. It is a martensitic stainless steel seamless steel pipe for oil well pipes that has a yield strength of 95 ksi class (655 to 758 MPa) and a low hardness of less than 27 in HRC and excellent in SSC resistance.
Hereinafter, the present invention will be described based on examples.
表1に示す組成の溶鋼を脱ガス後、連続鋳造法でビレット(大きさ:207mmφ)に鋳造し、鋼管素材とした。これら鋼管素材を加熱し、マンネスマン方式の製造工程を用いて熱間加工し造管したのち、空冷して、継目無鋼管(外径177.8mmφ×肉厚12.7mm)とした。
得られた継目無鋼管から、試験材(鋼管)を採取し、該試験材(鋼管)に表2に示す条件で焼入れ処理、焼戻処理を施した。
The molten steel having the composition shown in Table 1 was degassed and cast into billets (size: 207 mmφ) by a continuous casting method to obtain a steel pipe material. These steel pipe materials were heated, hot-processed using the Mannesmann manufacturing process, piped, and then air-cooled to obtain seamless steel pipes (outer diameter 177.8 mmφ x wall thickness 12.7 mm).
A test material (steel pipe) was collected from the obtained seamless steel pipe, and the test material (steel pipe) was quenched and tempered under the conditions shown in Table 2.
焼入れ処理および焼戻処理を施された試験材(鋼管)から、組織観察用試験片を採取した。組織観察用試験片を研磨した後、残留γ量を、X線回折法を用いて測定した。
また、焼入れ処理および焼戻処理試験材(鋼管)から、引張方向が管軸方向となるように、API弧状引張試験片を採取し、API−5CTの規定に準拠して、引張試験を実施し引張特性(降伏強さYS、引張強さTS)を求めた。
From the test material (steel pipe) subjected to the quenching treatment and the tempering treatment, a structure observation specimen was collected. After polishing the tissue observation specimen, the amount of residual γ was measured using an X-ray diffraction method.
Also, API arc-shaped tensile test specimens are collected from the quenching and tempering test materials (steel pipes) so that the tensile direction is in the direction of the pipe axis, and a tensile test is performed in accordance with the provisions of API-5CT. Tensile properties (yield strength YS, tensile strength TS) were determined.
また、焼入れ処理および焼戻処理を施された試験材から、JIS Z 2242の規定に準拠して、Vノッチ試験片(10mm厚)を採取し、シャルピー衝撃試験を実施し、破面遷移温度Trs50を求め、靭性を評価した。
また、試験材から、厚さ3mm×幅30mm×長さ40mmの腐食試験片を機械加工によって作製し、腐食試験を実施した。
In addition, V-notched specimens (10 mm thick) were sampled from test materials that had been quenched and tempered in accordance with JIS Z 2242, conducted Charpy impact tests, and fracture surface transition temperature Trs50 And toughness was evaluated.
Moreover, a corrosion test piece having a thickness of 3 mm, a width of 30 mm, and a length of 40 mm was produced from the test material by machining, and a corrosion test was performed.
腐食試験は、オートクレーブ中に保持された試験液:20%NaCl水溶液(液温:150℃、30気圧のCO2ガス雰囲気)中に、腐食試験片を浸漬し、浸漬期間を1週間(168h)として実施した。腐食試験後の試験片について、重量を測定し、腐食試験前後の重量減から、腐食速度を算出した。
また、SSC試験は、NACE TM0177の Method−Aに準拠して実施した。試験溶液は5%NaCl-0.5%CH3COOH水溶液にCH3COONaを加えてpHを3.5としたものを用いた。なお、硫化水素分圧は0.10barとした。負荷応力は655MPaとした。
Corrosion test, the test solution retained in the autoclave: 20% NaCl aqueous solution (liquid temperature: 0.99 ° C., CO 2 gas atmosphere at 30 atm) during the corrosion test piece was immersed for one week immersion period (168h) As implemented. The test piece after the corrosion test was weighed, and the corrosion rate was calculated from the weight loss before and after the corrosion test.
The SSC test was performed in accordance with NACE TM0177 Method-A. The test solution used was a 5% NaCl-0.5% CH 3 COOH aqueous solution with CH 3 COONa added to a pH of 3.5. The hydrogen sulfide partial pressure was 0.10 bar. The applied stress was 655 MPa.
得られた結果を表3に示す。 The obtained results are shown in Table 3.
本発明例はいずれも、油井管として十分な耐食性を有し、さらにYSが95ksi以上の高降伏強さとHRCで27未満の低硬さを満足し、靭性および耐SSC性に優れたマルテンサイト系ステンレス継目無鋼管となっている。また、本発明例は、焼戻温度の変化に対し、降伏強さの変化が小さい鋼管となっている。一方、本発明の範囲から外れる比較例は、硬さが高すぎ、所望の低硬さを満足できず、あるいは、焼戻温度の変化に対する降伏強さの変化が大きいか、あるいは靱性が低下するかさらには所望の耐食性、とくに優れた耐SSC性を確保できていない。 All of the examples of the present invention have sufficient corrosion resistance as an oil well pipe, further satisfy a high yield strength of YS of 95 ksi or more and a low hardness of less than 27 in HRC, and have excellent toughness and SSC resistance. Stainless steel seamless steel pipe. Moreover, the example of this invention is a steel pipe with a small change of yield strength with respect to the change of tempering temperature. On the other hand, the comparative examples that are out of the scope of the present invention are too hard to satisfy the desired low hardness, or the change in yield strength with respect to the change in tempering temperature is large, or the toughness is reduced. Furthermore, desired corrosion resistance, particularly excellent SSC resistance cannot be ensured.
Claims (3)
C:0.015%以下、 N:0.015%以下、
Si:1.0%以下、 Mn:2.0%以下、
P:0.020%以下、 S:0.010%以下、
Al:0.01〜0.10%、 Cr:10〜14%、
Ni:3〜8%以下、 Ti:0.03〜0.15%、
N:0.015%以下
を含み、さらに、Cu:1〜4%、Mo:1〜4%、W:1〜4%、Co:1〜4%のうちから選ばれた1種または2種以上を含有し、残部Feおよび不可避的不純物からなる組成を有するステンレス継目無鋼管に、
750〜840℃の範囲の温度に加熱したのち焼入れする焼入れ処理と、
650℃以下の温度で焼き戻す焼戻処理と、
を施し、YS95ksi級の高強度とロックウェルC硬さHRC27未満の低硬さとを兼備し、耐SSC性に優れるステンレス継目無鋼管とすることを特徴とする油井管用マルテンサイト系ステンレス継目無鋼管の製造方法。 % By mass
C: 0.015% or less, N: 0.015% or less,
Si: 1.0% or less, Mn: 2.0% or less,
P: 0.020% or less, S: 0.010% or less,
Al: 0.01-0.10%, Cr: 10-14%,
Ni: 3 to 8% or less, Ti: 0.03 to 0.15%,
N: 0.015% or less, further Cu: 1-4%, Mo: 1-4%, W: 1-4%, Co: 1 to 4% selected from 1 to 4% Containing stainless steel seamless steel pipe having a composition consisting of the remainder Fe and inevitable impurities,
A quenching process in which the steel is heated to a temperature in the range of 750 to 840 ° C. and then quenched.
Tempering treatment tempering at a temperature of 650 ° C or lower,
Of martensitic stainless steel seamless pipe for oil well pipes, which has a high strength of YS95ksi class and low hardness of less than Rockwell C hardness HRC27 and is excellent in SSC resistance. Production method.
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP2009092055A JP5487689B2 (en) | 2009-04-06 | 2009-04-06 | Manufacturing method of martensitic stainless steel seamless pipe for oil well pipe |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP2009092055A JP5487689B2 (en) | 2009-04-06 | 2009-04-06 | Manufacturing method of martensitic stainless steel seamless pipe for oil well pipe |
Publications (2)
Publication Number | Publication Date |
---|---|
JP2010242163A true JP2010242163A (en) | 2010-10-28 |
JP5487689B2 JP5487689B2 (en) | 2014-05-07 |
Family
ID=43095494
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
JP2009092055A Active JP5487689B2 (en) | 2009-04-06 | 2009-04-06 | Manufacturing method of martensitic stainless steel seamless pipe for oil well pipe |
Country Status (1)
Country | Link |
---|---|
JP (1) | JP5487689B2 (en) |
Cited By (22)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
WO2012117546A1 (en) * | 2011-03-03 | 2012-09-07 | エヌケーケーシームレス鋼管株式会社 | LOW-C, HIGH-Cr STEEL PIPE OF 862 MPa GRADE WITH HIGH CORROSION RESISTANCE, AND PROCESS FOR PRODUCING SAME |
JP2015161010A (en) * | 2014-02-28 | 2015-09-07 | Jfeスチール株式会社 | Martensitic stainless steel tube for line pipe excellent in reel barge construction property and manufacturing method therefor |
CN104968808A (en) * | 2013-01-31 | 2015-10-07 | 杰富意钢铁株式会社 | Manufacturing method and manufacturing equipment for seamless steel pipe or tube with excellent toughness |
JP2017013075A (en) * | 2015-06-26 | 2017-01-19 | 新日鐵住金株式会社 | Production method for martensitic stainless steel tube |
WO2017168874A1 (en) * | 2016-03-29 | 2017-10-05 | Jfeスチール株式会社 | High-strength seamless stainless-steel pipe for oil well |
WO2017200083A1 (en) * | 2016-05-20 | 2017-11-23 | 新日鐵住金株式会社 | Steel bar for downhole member and downhole member |
WO2018079111A1 (en) | 2016-10-25 | 2018-05-03 | Jfeスチール株式会社 | Seamless pipe of martensitic stainless steel for oil well pipe, and method for producing seamless pipe |
WO2019065116A1 (en) | 2017-09-29 | 2019-04-04 | Jfeスチール株式会社 | Oil well pipe martensitic stainless seamless steel pipe and production method for same |
WO2019065114A1 (en) | 2017-09-29 | 2019-04-04 | Jfeスチール株式会社 | Oil well pipe martensitic stainless seamless steel pipe and production method for same |
WO2019065115A1 (en) | 2017-09-29 | 2019-04-04 | Jfeスチール株式会社 | Oil well pipe martensitic stainless seamless steel pipe and production method for same |
WO2019225280A1 (en) | 2018-05-25 | 2019-11-28 | Jfeスチール株式会社 | Martensitic stainless steel seamless steel tube for oil well pipes, and method for producing same |
WO2019225281A1 (en) | 2018-05-25 | 2019-11-28 | Jfeスチール株式会社 | Martensitic stainless steel seamless steel tube for oil well pipes, and method for producing same |
WO2020067247A1 (en) * | 2018-09-27 | 2020-04-02 | 日本製鉄株式会社 | Martensitic stainless steel material |
WO2020095559A1 (en) | 2018-11-05 | 2020-05-14 | Jfeスチール株式会社 | Seamless martensite stainless steel tube for oil well pipes, and method for manufacturing same |
JP2020531691A (en) * | 2017-08-25 | 2020-11-05 | 宝山鋼鉄股▲分▼有限公司 | Refining method of ultra-low carbon 13Cr stainless steel |
US10876183B2 (en) | 2015-07-10 | 2020-12-29 | Jfe Steel Corporation | High-strength seamless stainless steel pipe and method of manufacturing high-strength seamless stainless steel pipe |
CN113186462A (en) * | 2021-04-20 | 2021-07-30 | 钢铁研究总院 | High-strength Cr-Ni-Co-Mo stainless steel for ultralow temperature and toughening heat treatment method |
US11268161B2 (en) | 2017-01-13 | 2022-03-08 | Jfe Steel Corporation | High strength seamless stainless steel pipe and method for producing same |
CN114318123A (en) * | 2020-09-29 | 2022-04-12 | 宝山钢铁股份有限公司 | High-strength low-hardness low-cost 13Cr oil casing steel, oil casing and manufacturing method thereof |
US11306369B2 (en) | 2017-02-24 | 2022-04-19 | Jfe Steel Corporation | High-strength stainless steel seamless pipe for oil country tubular goods, and method for producing same |
CN114717472A (en) * | 2022-01-27 | 2022-07-08 | 天津钢管制造有限公司 | Low-hardness alloy seamless steel pipe and heat treatment method |
CN114829647A (en) * | 2019-12-24 | 2022-07-29 | 杰富意钢铁株式会社 | High-strength stainless steel seamless steel pipe for oil well |
Families Citing this family (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US11965232B2 (en) * | 2018-10-02 | 2024-04-23 | Nippon Steel Corporation | Martensitic stainless seamless steel pipe |
Citations (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPH02243740A (en) * | 1989-03-15 | 1990-09-27 | Sumitomo Metal Ind Ltd | Martensitic stainless steel material for oil well and its manufacture |
JP2002105603A (en) * | 2000-10-04 | 2002-04-10 | Nkk Corp | Martensitic stainless steel |
JP2002105604A (en) * | 2000-10-05 | 2002-04-10 | Kawasaki Steel Corp | HIGH-Cr MARTENSITIC STAINLESS STEEL PIPE FOR LINEPIPE HAVING EXCELLENT CORROSION RESISTANCE AND WELDABILITY, AND ITS PRODUCTION METHOD |
-
2009
- 2009-04-06 JP JP2009092055A patent/JP5487689B2/en active Active
Patent Citations (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPH02243740A (en) * | 1989-03-15 | 1990-09-27 | Sumitomo Metal Ind Ltd | Martensitic stainless steel material for oil well and its manufacture |
JP2002105603A (en) * | 2000-10-04 | 2002-04-10 | Nkk Corp | Martensitic stainless steel |
JP2002105604A (en) * | 2000-10-05 | 2002-04-10 | Kawasaki Steel Corp | HIGH-Cr MARTENSITIC STAINLESS STEEL PIPE FOR LINEPIPE HAVING EXCELLENT CORROSION RESISTANCE AND WELDABILITY, AND ITS PRODUCTION METHOD |
Cited By (44)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
WO2012117546A1 (en) * | 2011-03-03 | 2012-09-07 | エヌケーケーシームレス鋼管株式会社 | LOW-C, HIGH-Cr STEEL PIPE OF 862 MPa GRADE WITH HIGH CORROSION RESISTANCE, AND PROCESS FOR PRODUCING SAME |
JP5793556B2 (en) * | 2011-03-03 | 2015-10-14 | エヌケーケーシームレス鋼管株式会社 | 862 MPa class low C high Cr steel pipe having high corrosion resistance and manufacturing method thereof |
US9677160B2 (en) | 2011-03-03 | 2017-06-13 | Nkk Tubes | Low C-high Cr 862 MPa-class steel tube having excellent corrosion resistance and a manufacturing method thereof |
CN104968808A (en) * | 2013-01-31 | 2015-10-07 | 杰富意钢铁株式会社 | Manufacturing method and manufacturing equipment for seamless steel pipe or tube with excellent toughness |
US20150368734A1 (en) * | 2013-01-31 | 2015-12-24 | Jfe Steel Corporation | Method and facility for manufacturing seamless steel pipe with excellent toughness |
EP2952592A4 (en) * | 2013-01-31 | 2016-04-27 | Jfe Steel Corp | Manufacturing method and manufacturing equipment for seamless steel pipe or tube with excellent toughness |
JP2015161010A (en) * | 2014-02-28 | 2015-09-07 | Jfeスチール株式会社 | Martensitic stainless steel tube for line pipe excellent in reel barge construction property and manufacturing method therefor |
JP2017013075A (en) * | 2015-06-26 | 2017-01-19 | 新日鐵住金株式会社 | Production method for martensitic stainless steel tube |
US10876183B2 (en) | 2015-07-10 | 2020-12-29 | Jfe Steel Corporation | High-strength seamless stainless steel pipe and method of manufacturing high-strength seamless stainless steel pipe |
WO2017168874A1 (en) * | 2016-03-29 | 2017-10-05 | Jfeスチール株式会社 | High-strength seamless stainless-steel pipe for oil well |
JPWO2017168874A1 (en) * | 2016-03-29 | 2018-04-05 | Jfeスチール株式会社 | High strength stainless steel seamless steel pipe for oil well |
EP3438305A4 (en) * | 2016-03-29 | 2019-02-06 | JFE Steel Corporation | High-strength seamless stainless-steel pipe for oil well |
US11414719B2 (en) | 2016-03-29 | 2022-08-16 | Jfe Steel Corporation | High strength stainless steel seamless pipe for oil country tubular goods |
US20190136337A1 (en) * | 2016-03-29 | 2019-05-09 | Jfe Steel Corporation | High strength stainless steel seamless pipe for oil country tubular goods |
JP6264521B1 (en) * | 2016-05-20 | 2018-01-24 | 新日鐵住金株式会社 | Steel bar for downhole member and downhole member |
WO2017200083A1 (en) * | 2016-05-20 | 2017-11-23 | 新日鐵住金株式会社 | Steel bar for downhole member and downhole member |
US10995394B2 (en) | 2016-05-20 | 2021-05-04 | Nippon Steel Corporation | Steel bar for downhole member, and downhole member |
RU2710808C1 (en) * | 2016-05-20 | 2020-01-14 | Ниппон Стил Корпорейшн | Steel long products for well element and well element |
WO2018079111A1 (en) | 2016-10-25 | 2018-05-03 | Jfeスチール株式会社 | Seamless pipe of martensitic stainless steel for oil well pipe, and method for producing seamless pipe |
US11268161B2 (en) | 2017-01-13 | 2022-03-08 | Jfe Steel Corporation | High strength seamless stainless steel pipe and method for producing same |
US11306369B2 (en) | 2017-02-24 | 2022-04-19 | Jfe Steel Corporation | High-strength stainless steel seamless pipe for oil country tubular goods, and method for producing same |
JP2020531691A (en) * | 2017-08-25 | 2020-11-05 | 宝山鋼鉄股▲分▼有限公司 | Refining method of ultra-low carbon 13Cr stainless steel |
US11401570B2 (en) | 2017-09-29 | 2022-08-02 | Jfe Steel Corporation | Martensitic stainless steel seamless pipe for oil country tubular goods, and method for manufacturing same |
WO2019065115A1 (en) | 2017-09-29 | 2019-04-04 | Jfeスチール株式会社 | Oil well pipe martensitic stainless seamless steel pipe and production method for same |
WO2019065114A1 (en) | 2017-09-29 | 2019-04-04 | Jfeスチール株式会社 | Oil well pipe martensitic stainless seamless steel pipe and production method for same |
US11827949B2 (en) | 2017-09-29 | 2023-11-28 | Jfe Steel Corporation | Martensitic stainless steel seamless pipe for oil country tubular goods, and method for manufacturing same |
EP3690074A4 (en) * | 2017-09-29 | 2020-08-05 | JFE Steel Corporation | Oil well pipe martensitic stainless seamless steel pipe and production method for same |
WO2019065116A1 (en) | 2017-09-29 | 2019-04-04 | Jfeスチール株式会社 | Oil well pipe martensitic stainless seamless steel pipe and production method for same |
JP6540921B1 (en) * | 2017-09-29 | 2019-07-10 | Jfeスチール株式会社 | Martensitic stainless steel seamless steel pipe for oil well pipe and method for producing the same |
JP6540922B1 (en) * | 2017-09-29 | 2019-07-10 | Jfeスチール株式会社 | Martensitic stainless steel seamless steel pipe for oil well pipe and method for producing the same |
JP6540920B1 (en) * | 2017-09-29 | 2019-07-10 | Jfeスチール株式会社 | Martensitic stainless steel seamless steel pipe for oil well pipe and method for producing the same |
WO2019225281A1 (en) | 2018-05-25 | 2019-11-28 | Jfeスチール株式会社 | Martensitic stainless steel seamless steel tube for oil well pipes, and method for producing same |
WO2019225280A1 (en) | 2018-05-25 | 2019-11-28 | Jfeスチール株式会社 | Martensitic stainless steel seamless steel tube for oil well pipes, and method for producing same |
US11773461B2 (en) | 2018-05-25 | 2023-10-03 | Jfe Steel Corporation | Martensitic stainless steel seamless pipe for oil country tubular goods, and method for manufacturing same |
WO2020067247A1 (en) * | 2018-09-27 | 2020-04-02 | 日本製鉄株式会社 | Martensitic stainless steel material |
JPWO2020067247A1 (en) * | 2018-09-27 | 2021-08-30 | 日本製鉄株式会社 | Martensitic stainless steel |
JP6743992B1 (en) * | 2018-11-05 | 2020-08-19 | Jfeスチール株式会社 | Martensitic stainless seamless steel pipe for oil country tubular goods and method for producing the same |
WO2020095559A1 (en) | 2018-11-05 | 2020-05-14 | Jfeスチール株式会社 | Seamless martensite stainless steel tube for oil well pipes, and method for manufacturing same |
CN114829647A (en) * | 2019-12-24 | 2022-07-29 | 杰富意钢铁株式会社 | High-strength stainless steel seamless steel pipe for oil well |
EP4043591A4 (en) * | 2019-12-24 | 2022-10-12 | JFE Steel Corporation | High-strength stainless steel seamless pipe for oil wells |
CN114318123A (en) * | 2020-09-29 | 2022-04-12 | 宝山钢铁股份有限公司 | High-strength low-hardness low-cost 13Cr oil casing steel, oil casing and manufacturing method thereof |
CN113186462A (en) * | 2021-04-20 | 2021-07-30 | 钢铁研究总院 | High-strength Cr-Ni-Co-Mo stainless steel for ultralow temperature and toughening heat treatment method |
CN114717472B (en) * | 2022-01-27 | 2024-03-15 | 天津钢管制造有限公司 | Low-hardness alloy seamless steel pipe and heat treatment method |
CN114717472A (en) * | 2022-01-27 | 2022-07-08 | 天津钢管制造有限公司 | Low-hardness alloy seamless steel pipe and heat treatment method |
Also Published As
Publication number | Publication date |
---|---|
JP5487689B2 (en) | 2014-05-07 |
Similar Documents
Publication | Publication Date | Title |
---|---|---|
JP5487689B2 (en) | Manufacturing method of martensitic stainless steel seamless pipe for oil well pipe | |
JP5145793B2 (en) | Martensitic stainless steel seamless pipe for oil well pipe and method for producing the same | |
US11072835B2 (en) | High-strength seamless stainless steel pipe for oil country tubular goods, and method for producing the same | |
JP6460229B2 (en) | High strength stainless steel seamless steel pipe for oil well | |
JP5211841B2 (en) | Manufacturing method of duplex stainless steel pipe | |
RU2459884C1 (en) | Tube from high-strength stainless steel with high cracking resistance at strains in sulphide-bearing medium and high-temperature gas corrosion resistance on exposure to carbon dioxide | |
JP4978073B2 (en) | High toughness ultra-high strength stainless steel pipe for oil wells with excellent corrosion resistance and method for producing the same | |
WO2017138050A1 (en) | High strength stainless steel seamless pipe for oil well and manufacturing method therefor | |
CN110168124B (en) | Duplex stainless steel and method for producing same | |
JP6237873B2 (en) | High strength stainless steel seamless steel pipe for oil well | |
JP6156609B1 (en) | High strength stainless steel seamless steel pipe for oil well and method for producing the same | |
JP2015110822A (en) | High strength seamless stainless steel tube for oil well, having excellent corrosion resistance, and method for manufacturing the same | |
EA025503B1 (en) | Method for producing high-strength steel material excellent in sulfide stress cracking resistance | |
WO2014112353A1 (en) | Stainless steel seamless tube for use in oil well and manufacturing process therefor | |
JP5499575B2 (en) | Martensitic stainless steel seamless pipe for oil well pipe and method for producing the same | |
WO2019065116A1 (en) | Oil well pipe martensitic stainless seamless steel pipe and production method for same | |
WO2017149570A1 (en) | Low-alloy, high-strength seamless steel pipe for oil well | |
WO2017149571A1 (en) | Low-alloy, high-strength seamless steel pipe for oil well | |
WO2019065115A1 (en) | Oil well pipe martensitic stainless seamless steel pipe and production method for same | |
CN112955576A (en) | Martensitic stainless steel seamless steel pipe for oil well pipe and method for producing same | |
JP6859921B2 (en) | Stainless steel materials and stainless steel pipes | |
JP2006152332A (en) | Martensitic stainless steel pipe and manufacturing method therefor | |
JP7207557B2 (en) | Stainless seamless steel pipe for oil country tubular goods and manufacturing method thereof | |
CN115917028A (en) | Stainless steel seamless steel pipe and method for manufacturing same | |
JP6152929B1 (en) | Low alloy high strength seamless steel pipe for oil wells |
Legal Events
Date | Code | Title | Description |
---|---|---|---|
A621 | Written request for application examination |
Free format text: JAPANESE INTERMEDIATE CODE: A621 Effective date: 20120223 |
|
RD03 | Notification of appointment of power of attorney |
Free format text: JAPANESE INTERMEDIATE CODE: A7423 Effective date: 20130710 |
|
A977 | Report on retrieval |
Free format text: JAPANESE INTERMEDIATE CODE: A971007 Effective date: 20130925 |
|
A131 | Notification of reasons for refusal |
Free format text: JAPANESE INTERMEDIATE CODE: A131 Effective date: 20131015 |
|
A521 | Request for written amendment filed |
Free format text: JAPANESE INTERMEDIATE CODE: A523 Effective date: 20131125 |
|
TRDD | Decision of grant or rejection written | ||
A01 | Written decision to grant a patent or to grant a registration (utility model) |
Free format text: JAPANESE INTERMEDIATE CODE: A01 Effective date: 20140128 |
|
A61 | First payment of annual fees (during grant procedure) |
Free format text: JAPANESE INTERMEDIATE CODE: A61 Effective date: 20140210 |
|
R150 | Certificate of patent or registration of utility model |
Ref document number: 5487689 Country of ref document: JP Free format text: JAPANESE INTERMEDIATE CODE: R150 |
|
R250 | Receipt of annual fees |
Free format text: JAPANESE INTERMEDIATE CODE: R250 |
|
R250 | Receipt of annual fees |
Free format text: JAPANESE INTERMEDIATE CODE: R250 |
|
R250 | Receipt of annual fees |
Free format text: JAPANESE INTERMEDIATE CODE: R250 |
|
R250 | Receipt of annual fees |
Free format text: JAPANESE INTERMEDIATE CODE: R250 |