• 专利附录
  • 专利说明
  • 权利要求
  • 类似技术
  • 同族专利
  • 引用文献
  • 法律状态
  • 优先权
    • 专利摘要:
    patent abstract: "High strength seamless stainless steel pipe for tubular oilfield materials and method for producing it". The present invention relates to a high strength stainless steel pipe for oil field tubular materials having a wall thickness of over 25.4 mm and a high strength of a 758 mpa (ksi 110), yield stress. of grade or more with excellent hardness and excellent corrosion resistance. a steel material having a chemical composition containing by weight% c: 0,005% or more and 0,06% or less itself: 0,05% or more and 0,5% or less, mn: 0,2 % or more and 1,8% or less, cr: 15,5% or more and 18,0% or less, ni: 1,5% or more and 5,0% or less, v: 0,02% or plus and 0.2% or less, al: 0.002% or more and 0.05% or less, n: 0.01% or more and 0.15% or less, o: 0.006% or less, and further containing a or more than mo: 1,0% or more and 3,5% or less, w: 3,0% or less and cu: 3,5% or less, where the expressions of relations cr + 0,65ni + 0 , 60mo + 0.30w + 0.55cu-20c³19.5 and cr + mo + 0.50w + 0.30si-43.5c-0.4mn-ni-0.3cu-9n³11.5 are met, is done in a seamless steel tube by heating and hot rolling. 22990057v1 1/1 22990057v1
    公开号:BR112014029392B1
    申请号:R112014029392-9
    申请日:2013-05-30
    公开日:2019-09-24
    发明作者:Yukio Miyata；Yasuhide Ishiguro；Kazutoshi Ishikawa；Tetsu Nakahashi
    申请人:Jfe Steel Corporation；
    IPC主号:
    专利说明:

    Descriptive Report of the Invention Patent for STAINLESS STEEL TUBE WITHOUT SEWING OF HIGH RESISTANCE FOR TUBULAR MATERIALS OF PETROLEUM FIELDS AND METHOD FOR PRODUCTION OF THE SAME.
    Technical Field [001] The present invention relates to a seamless steel tube for tubular oilfield materials, in particular to a high strength seamless steel tube having both excellent low temperature toughness and excellent corrosion resistance. Background [002] Currently, deep oil wells that had never been taken into account and hydrogen sulfide gas fields whose development was abandoned due to their intense corrosion environment are being actively developed on a global scale from the point of view of a sharp increase in the price of crude oil and the depletion of oil resources that is being forecast in the near future. Such oil wells and gas fields are generally found at great depths in the soil and in an environment of intense corrosion, in which the atmosphere has a high temperature and contains CO2, Cl - , etc. Therefore, steel tubes for tubular materials from oil fields that are used to drill such oil wells and gas fields needed to have not only high strength, but also excellent corrosion resistance.
    [003] For oil wells and gas fields in an environment of intense corrosion containing CO2, Cl - , etc., martensitic stainless steel tubes with 13% Cr were used as steel tubes for tubular materials in oil fields in the past. However, there was a problem that ordinary martensitic stainless tubes cannot be used in an environment containing a large amount of Cl - and having a high temperature, over 100 ° C.
    Petition 870190044649, of 05/13/2019, p. 11/49
    2/30 [004] Therefore, in such an environment of corrosion and high temperature, duplex stainless steel tubes were used. However, there is a problem with the fact that since duplex stainless tubes contain a large amount of chemical bonding elements and are poor in terms of hot forming, duplex stainless steels can be produced using only particular types of processing hot and expensive.
    [005] To solve the problems described above, for example, the
    Patent Literature 1 describes a method for producing a high strength stainless steel tube with excellent corrosion resistance, the method including producing a steel tube material having a chemical composition including, in mass%, C: 0.005% to 0 , 05%, Si: 0.05% to 0.5%, Mn: 0.2% to 1.8%, Cr: 15.5% to 18%, Ni: 1.5% to 5%, Mo: 1% to 3.5%, V: 0.02% to 0.2%, N: 0.01% to 0.15%, and O: 0.006% or less, in which the relations of the expressions (1) and (2) below are satisfied, in a tube having a size specified by performing hot processing for tube production, cooling the tube to room temperature at a cooling rate equal to or greater than the air cooling rate. after tube production has been carried out and quenching the tube by reheating the tube to a temperature of 850 ° C or more, subsequently cooling the heated tube to a temperature of 100 ° C or less at a rate of cooling equal to u higher than the air cooling rate and then heating the cooled tube to a temperature of 700 ° C or less.
    Cr + 0.65Ni + 0.60Mo + 0.30W + 0.55Cu - 20C> 19.5 (1) (where the contents of Cr, Ni, Mo. W, Cu and C (mass%) of the chemical elements are respectively represented by the corresponding atomic symbols)
    Cr + Mo + 0.50W + 0.30Si-43.5C-0.4Mn-Ni-0.3Cu-9N> 11.5 (2)
    Petition 870190044649, of 05/13/2019, p. 12/49
    3/30 (where the contents of Cr, Mo, W, Si, C, Mn, Ni, Cu and N (% by mass) of the chemical elements are represented respectively by the corresponding atomic symbols). According to the technique described in Patent Literature 1, a high-strength stainless steel tube for tubular oilfield materials having sufficient effective corrosion resistance even in an environment of intense corrosion having an increased concentration of CO2, Cl-, etc. ., and an increased temperature of up to about 200 ° C in which a martensitic stainless steel with 13% Cr cannot be used, it can be stably produced.
    [006] In addition, Patent Literature 2 describes a method for producing a stainless steel tube, the method including producing a bar having a chemical composition containing, in mass%, C: 0001% to 0.05%, Si: 0.05% to 1%, Mn: 2% or less, Cr: 16% to 18%, Ni: 3.5% to 7%, Mo: more than 2% and 4% or less, Cu: 1 , 5% to 4%, rare earth element: 0.001% to 0.3%, Al sol .: 0.001% to 0.1%, Ca: 0.0001% to 0.3%, N: 0.05% or less and O: 0.05% or less, or also containing one or more elements selected from the group consisting of Ti: 0.5% or less, Zr: 0.5% or less, Hf: -0.5% or less and V: 0.5% or less in a steel tube by performing a hot processing and then quenching the steel tube. According to the technique described in Patent Literature 2, a stainless steel tube for tubular materials for oil fields can be produced having not only sufficiently effective corrosion resistance even in an environment of intense corrosion having a high temperature of up to about 130 ° C but also high strength.
    List of Citations
    Patent Literature [007] PTL 1 - Patent Application Publication not examined
    Petition 870190044649, of 05/13/2019, p. 13/49
    4/30
    Japanese No. 2005-336595 [008] PTL 2 - Japanese Patent No. 4577457
    Summary of the Invention
    Technical Problem [009] Currently, since oil wells and gas fields that are discovered very deep in the ground are being drilled more often than before, tubes for tubular materials from oil fields having a thick wall are required to prevent the tubes for tubular materials from oil fields are pressed due to the pressure of a geological layer. In the case of the technique described in Patent Literature 2, there is the problem that, when the tube has a wall thickness of more than 25.4 mm, the toughness deteriorates and thus the desired high toughness and high strength cannot be achieved at the same time.
    [0010] An objective of the present invention is, by solving the problems of the conventional techniques described above, to provide a seamless high strength stainless steel tube for tubular materials from oil fields having a wall thickness of more than 25.4 mm , having not only a high yield strength of a grade limit of 758 MPa (110 ksi) or more but also a high tenacity of 40 J or more in terms of absorbed energy vE-10 determined by performing a Charpy impact test at a test temperature of -10 ° C, and, in addition, having excellent corrosion resistance and a method for producing the steel tube. Here, excellent corrosion resistance refers to a case in which a pipe has excellent resistance to corrosion by CO2 effective even in a corrosion environment having a high temperature of 230 ° C or more and containing CO2 and Cl - .
    Solution to the Problem [0011] To achieve the objective described above, initially the
    Petition 870190044649, of 05/13/2019, p. 14/49
    5/30 present inventors have diligently conducted investigations into various factors that have an influence on toughness, and, as a result, have found it necessary to form a microstructure having a decreased grain diameter to increase the toughness of a stainless steel tube that has a thick wall. In the case of stainless steel having a chemical composition containing 16% to 18% Cr and about 2% to 6% Ni to increase corrosion resistance, the ferrite phase crystallizes at the moment of solidification, and part of the ferrite phase is transformed in austenite phase when stainless steel is cooled to room temperature. However, since the ferrite phase is not completely eliminated and part of the ferrite phase is retained, it is almost impossible to decrease the grain diameter even when thermal treatment is carried out later. Therefore, the present inventors thought of using a GSI spacing value (grain size index) between various phases such as ferrite phase and austenite phase (or martensite phase) as an index that expresses the degree of decrease in the grain diameter of a microstructure and found that in the case of a stainless steel tube having a chemical composition containing 16% to 18% Cr and about 1% to 6% Ni, there is an increase in toughness by decreasing the GSI value, that is, by decreasing the spacing between the various phases.
    [0012] From the results of such investigations by the present inventors, it has been found that when a hot processing including boring lamination is performed, there is a decrease in the GSI spacing between various phases by performing the hot processing under conditions such that the reduction of the rolling in a specified temperature range is equal to or greater than a certain value, resulting in a significant increase in toughness.
    [0013] Initially, the experimental results that became the basis of the present invention will be described.
    Petition 870190044649, of 05/13/2019, p. 15/49
    6/30 [0014] Steel materials (bars) having chemical composition containing, in mass%, 0.026% C, 0.20% Si, 0.24% Mn, 001% P, 0.001% S , 16.7% Cr, 3.11% Ni, 0.027% V, 2.13% Mo, 1.06% W, 0.51% Cu ,. 0.02% Al, 0.051% N and the balance being Fe and the inevitable impurities were heated to various heating temperatures. In addition, by carrying out hot rolling using a boring mill, an elongation mill, a mill with milling, etc., at various temperatures with various rolling reductions, seamless steel tubes having an outside diameter of 297 mm and a wall thickness from 26 to 34 mm were produced and cooled to room temperature by air cooling. Using a specimen to observe the microstructure that has been cut from the obtained steel tube, polished and etched with a Vilella reagent, a microstructure was observed using an optical microscope (at 400 times magnification). Performing the image analysis on the photograph taken of the microstructure, the GSI value was determined as an index representing the degree of decrease in the grain diameter of the microstructure. The GSI value was determined by counting the number of edges of ferrite-martensite grain per unit length (line / mm) in the direction of the wall thickness using the photograph of the microstructure obtained. In addition, using a Charpy impact specimen (having a thickness of 10 mm) cut from the steel tube obtained in the longitudinal direction of the steel tube, the absorbed energy vE-10 (J) at a temperature of -10 ° C test. The results obtained are illustrated in the form of the relationship between vE-10 and the GSI value in FIG. 1.
    [0015] Fig. 1 indicates that it is necessary to decrease the grain diameter of a microstructure for GSI: 120 or more to achieve the toughness of vE-10: 40 J or more. Incidentally, from the results of other experiments, the present inventors confirmed that a decrease
    Petition 870190044649, of 05/13/2019, p. 16/49
    7/30 tion in the grain diameter of a microstructure for GSI: 120 or more can be achieved by performing hot rolling under conditions such that the total rolling reduction in a temperature range of 1100 ° C to 900 ° C is 30% or more. In the case of hot rolling including boring rolling where the plate is heated to a common heating temperature (1100 ° C to 1250 ° C), the temperature range from 1100 ° C to 900 ° C corresponds to the lamination using a elongation laminator and mandrel laminator. That is to say, it was discovered that to increase the low temperature toughness of a seamless steel tube, that is, to decrease the grain diameter of a microstructure, it is necessary that a lamination using an elongation laminator or a mandrel laminator, etc., be performed under conditions such that the temperature is low and the lamination reduction is high, that is, the total lamination reduction is 30% or more.
    [0016] The present invention has been completed on the basis of the knowledge described above and other investigations. That is, the subject of the present invention is as follows.
    [0017] (1) A method for producing a high strength seamless stainless steel tube for oilfield oil materials having a wall thickness of more than 25.4 mm, the method including heating the steel material ; hot rolling, including boring rolling, the steel material in a seamless steel tube; and cooling the seamless steel tube to room temperature at a cooling rate equal to or greater than an air cooling rate, the steel material having a chemical composition containing, in mass%, C: 0.005% or more and 0.06% or less, Si: 0.05% or more and 0.5% or less, Mn: 0.2% or more and 1.8% or less, P: 0.03% or less, S : 0.005% or less, Cr: 15.5% or more and 18.0% or less, Ni: 1.5% or more and 5.0% or less, V: 0.02% or more and
    Petition 870190044649, of 05/13/2019, p. 17/49
    8/30
    0.2% or less, Al: 0.002% or more and 0.05% or less, N: 0.01% or more and 0.15% or less, O: 0.006% or less, and also containing one, two or more elements selected from Mo: 1.0% or more and 3.5% or less, W: 3.0% or less and Cu: 3.5% or less and the balance being Fe and the inevitable impurities, in which the relational expressions (1) and (2) below are satisfied, hot rolling including boring rolling is performed under conditions such that the total rolling reduction in a temperature range of 1100 ° C to 900 ° C is 30% or further, and after the cold rolled steel tube is cooled to room temperature, quenching or quenching is performed:
    Cr + 0.65Ni + 0.60Mo + 0.30W + 0.55Cu - 20C> 19.5 (1) (where Cr, Ni, Mo, W, Cu and C: contents (% by mass) of the chemical elements respectively represented by the corresponding atomic symbols)
    Cr + Mo + 050W + 0.30Si-43.5C-0.4Mn-Ni-0.3Cu-9N> 11.5 (2) (where Cr, Mo, W, Si, C, Mn, Ni, Cu and N: contents (% by mass) of the chemical elements represented by the corresponding atomic symbols respectively).
    [0018] (2) The method for producing a seamless high-strength stainless steel tube for tubular oilfield materials as per item (1), in which the chemical composition also contains, in mass%, one or more elements selected from Nb: 0.2% or less, Ti: 0.3% or less, Zr: 0.2% or less and B: 0.01% or less.
    [0019] (3) The method for producing a seamless high strength stainless steel tube for tubular materials from oil fields as per item (1) or (2), in which the chemical composition also contains, in% in mass, Ca: 0.01% or less.
    [0020] (4) A high strength seamless stainless steel tube
    Petition 870190044649, of 05/13/2019, p. 18/49
    9/30 having a wall thickness of more than 25.4 mm, the steel tube having a chemical composition containing, in mass%, C: 0.005% or more and 0.06% or less, Si: 0, 05% or more and 0.5% or less, Mn: 0.2% or more and 1.8% or less, P: 0.03% or less, S: 0.005% or less, Cr: 15.5% or more and 18.0% or less, Ni: 1.5% or more and 5.0% or less, V: 0.02% or more and 0.2% or less, Al: 0.002% or more and 0 , 05% or less, N: 0.01% or more and 0.15% or less, O: 0.006% or less, and also containing one, two or more elements selected from Mo: 1.0% or more and 3 , 5% or less, W: 3.0% or less, and Cu: 3.5% or less and the balance being Fe and the inevitable impurities, in which the relational expressions (1) and (2) below are satisfied, having a microstructure including a martensite phase as the main phase and a second phase consisting, by volume, of 10% or more and 60% or less of a ferrite phase and 0% or more and 10% or less of an austenite phase, in which the GSI value, which is defined as on humerus of edges of ferrite-martensite grains per unit length of a line segment drawn in the direction of the wall thickness, is 120 or more in the central portion in the direction of the wall thickness, and having excellent low temperature toughness and excellent resistance to corrosion:
    Cr + 0.65Ni + 0.6Mo + 0.30W + 0.55Cu - 20C> 19.5 (1) (where Cr, Ni., Mo, W, Cu and C: contents (mass%) of the chemical elements represented respectively by the corresponding atomic symbols)
    Cr + Mo + 0.50W + 0.30Si-43.5C-0.4Mn-Ni-0.3Cu-9N> 11.5 (2) (where Cr, Mo, W, Si, C, Mn, Ni, Cu and N: contents (% by mass) of chemical elements represented by the corresponding atomic symbols respectively).
    [0021] (5) The high strength seamless stainless steel tube for tubular materials from oil fields as per item (4),
    Petition 870190044649, of 05/13/2019, p. 19/49
    10/30 in which the chemical composition also contains, in mass%, one or more elements selected from Nb: 0.2% or less, Ti: 0.3% or less, Zr: 0.2% or less and B : 0.01% or less.
    [0022] (6) The high strength seamless stainless steel tube for tubular oilfield materials according to item (4) or (5), in which the chemical composition also contains, in mass%, Ca: 0 , 01% or less.
    Advantageous Effects of the Invention [0023] According to the present invention, a high strength seamless stainless steel tube for tubular oilfield materials having a wall thickness of more than 25.4 mm, having not only a high strength the yield strength of 758 MPa (110 ksi) or more but also a high tenacity of 40 J or more in terms of absorbed energy vE-10 in a Charpy impact test, having excellent corrosion resistance can be easily produced at low cost, which results in a significant industrial effect.
    Brief Description of the Drawing [0024] - Fig. 1 is a graph illustrating the relationship between the energy absorbed vE-10 in a Charpy impact test and a GSI value. Description of Modalities [0025] Initially, the method for producing a seamless high-strength stainless steel tube for tubular oilfield materials according to the present invention will be described. In the present invention, a seamless steel tube is produced by heating a steel material and by performing hot rolling including boring rolling.
    [0026] The reasons for the limitations in the chemical composition of a steel material used in the present invention will be described later. Hereafter, mass% used when describing a
    Petition 870190044649, of 05/13/2019, p. 20/49
    11/30 chemical composition is represented simply by%, unless noted differently.
    [0027] The steel material used in the present invention has a chemical composition containing C: 0.005% or more and 0.06% or less, Si: 0.05% or more and 0.5% or less, Mn: 0, 2% or more and 1.8% or less, P: 0.03% or less, S: 0.005% or less, Cr: 15.5% or more and 18.0% or less, Ni: 1.5% or more and 5.0% or less, V: 0.02% or more and 0.2% or less, Al: 0.002% or more and 0.05% or less, N: 0.01% or more and 0 , 15% or less, O: 0.006% or less, and also containing one, two or more elements selected from Mo: 1.0% or more and 3.5% or less and the balance being Fe and the inevitable impurities, in the which relational expressions (1) and (2) below are satisfied.
    Cr + 0.65Ni + 0.60Mo + 0.30W + 0.55Cu - 20C> 19.5 (1) (where Cr, Ni, Mo, W, Cu and C: contents (% by mass) of the chemical elements represented respectively by the corresponding atomic symbols)
    Cr + Mo + 0.50W + 0.30Si-43.5C-0.4Mn-Ni-0.3Cu-9N> 11.5 (2) (where Cr, Mo, W, Si, C, Mn, Ni. Cu, and N: contents (% by mass) of the chemical elements represented by the corresponding atomic symbols respectively).
    [0028] C: 0.005% or more and 0.06% or less [0029] C is a chemical element that is related to an increase in the strength of martensitic stainless steel. It is necessary for the C content to be 0.005% or more in the present invention. On the other hand, in the case where the C content is greater than 0.06%, there is a significant deterioration in corrosion resistance. Therefore, the C content is limited to 0.005% or more and 0.06% or less, preferably 0.01% or more and 0.04% or less.
    [0030] Si: 0.05% or more and 0.5% or less [0031] Si is a chemical element that works as an agent
    Petition 870190044649, of 05/13/2019, p. 21/49
    12/30 deoxidation, and Si is added in the amount of 0.05% or more in the present invention. However, in the case where the Si content is greater than 0.5%, there is a deterioration in the resistance to corrosion by CO2 and a deterioration in the hot forming capacity. Therefore, the Si content is limited to 0.05% or more and 0.5% or less, preferably 0.1% or more and 0.4% or less [0032] Mn: 0.2% or more and 1 , 8% or less [0033] Mn is a chemical element that increases resistance, and
    Mn is added in the amount of 0.2% or more to achieve the high resistance desired in the present invention. On the other hand, in the case where the Mn content is greater than 1.8%, there is a negative influence on the toughness. Therefore the Mn content is limited to 0.2% or more and 1.8% or less, preferably 0.2% or more and 0.8% or less.
    [0034] P: 0.03% or less [0035] Since P is a chemical element that deteriorates corrosion resistance, it is preferable that the P content is as small as possible in the present invention. However, since the P content is controlled at a comparatively low cost without deteriorating the corrosion resistance in the case where the P content is 0.03% or less, it is acceptable for the P content to be about 0 , 03% or less. Therefore, the P content is limited to 0.03% or less. Since there is an increase in the cost of production in the event that the P content is excessively small, it is preferable that the P content is 0.005% or more.
    [0036] S: 0.005% or less [0037] Since S is a chemical element that significantly deteriorates the hot forming capacity, it is preferable that the SW content is as small as possible. However, it is acceptable for the S content to be 0.005% or less, because it is possible to produce a tube using normal processes in the event that the S content is
    Petition 870190044649, of 05/13/2019, p. 22/49
    13/30
    0.005% or less. Therefore. the S content is limited to 0.005% or less. Since there is an increase in the cost of production in the event that the S content is excessively small, it is preferable that the S content is 0.0005% or more.
    [0038] Cr: 15.5% or more and 18.0% or less [0039] Cr is a chemical element that increases corrosion resistance as a result of the formation of a protective film and, in particular, contributes to an increase in resistance to corrosion by CO2. The Cr content must be 15.5% or more to increase corrosion resistance at a high temperature. On the other hand, in the case where the Cr content is greater than 18%, there is a deterioration in the hot deformation capacity, and there is a decrease in strength. [0040] Ni: 1.5% or more and 5.0% or less [0041] Ni is a chemical element that is effective in increasing corrosion resistance by reinforcing a protective film and increasing the strength of steel as a result the formation of a solid solution. These effects become noticeable if the Ni content is 1.5% or more. On the other hand, in the case where the Ni content is greater than 5.0%, since there is a decrease in the stability of a martensite phase, there is a decrease in resistance. Therefore, the Ni content is limited to 1.5% or more and 5.0% or less, preferably 3.0% or more and 4.5% or less.
    [0042] V: 0.02% or more and 0.2% or less [0043] V contributes to an increase in strength by reinforcing the solid solution and is effective in increasing resistance to fracture by corrosion stress. The V content must be 0.02% or more to achieve these effects. On the other hand, in the case where the V content is greater than 0.2%, there is a deterioration in the toughness. Therefore, the V content is limited to 0.02% or more and 0.2% or less, preferably 0.03% or more and 0.08% or less.
    Petition 870190044649, of 05/13/2019, p. 23/49
    14/30 [0044] Al: 0.002% or more and 0.05% or less [0045] Al is a chemical element that works as a deoxidizing agent and the Al content must be 0.002% or more to perform this It is made. On the other hand, in the case where the Al content is greater than 0.05%, since there is an increase in the amount of alumina containing inclusions, there is a deterioration in ductility and toughness. Therefore, the Al content is limited to 0.002% or more and 0.05% or less, preferably 0.01% or more and 0.04% or less.
    [0046] N: 0.01% or more and 0.15% or less [0047] N is a chemical element that noticeably increases the resistance to localized corrosion, and the N content must be 0.01% or more in the present invention. On the other hand, in the case where the N content is greater than 0.15%, several nitrides are formed and there is a deterioration in the toughness. Therefore, the N content is limited to 0.01% or more and 0.15% or less, preferably 0.02% or more and 0.08% or less.
    [0048] O: 0.006% or less [0049] O is present in steel as an oxide and has a negative effect on ductility, toughness, etc. Therefore, it is preferable that the O content is as small as possible. In particular, in the case where the O content is greater than 0.006%, there is a significant deterioration in the hot forming capacity, toughness and corrosion resistance. Therefore, the O content is limited to 0.006% or less.
    [0050] One or two elements selected from Mo: 1.0% or more and 3.5% or less, W: 3.0% or less and Cu: 3.5% or less [0051] Since Mo , W and Cu are all chemical elements that increase corrosion resistance, one, two or more elements selected from these chemical elements are added.
    [0052] Mo is a chemical element that contributes to the increase
    Petition 870190044649, of 05/13/2019, p. 24/49
    15/30 of corrosion resistance by increasing the resistance to localized corrosion caused by Cl - , and the Mo content must be 1.0% or more. On the other hand, in the case where the Mo content is greater than 3.5%, there is a deterioration in strength and toughness and there is an increase in the cost of the material. Therefore, in the case where Mo is added, the Mo content is limited to 1.0% or more and 3.5% or less, preferably 1.5% or more and 3.0% or less.
    [0053] W is a chemical element that contributes to an increase in corrosion resistance like Mo, and it is preferable that the Mo content is 0.5% or more. However, in the case where the W content is greater than 3.0%, there is a deterioration in the toughness, there is an increase in the material cost. Therefore, in the case where W is added, the W content is limited to 3.0% or less, preferably 0.5% or more and 2.6% or less.
    [0054] Since Cu is effective in preventing hydrogen from penetrating steel by reinforcing a protective film, Cu contributes to an increase in corrosion resistance. It is preferable that the Cu content is 0.5% or more to achieve these effects. However, in the case where the Cu content is greater than 3.5%, there is a deterioration of the hot forming capacity. Therefore, in the case where Cu is added, the Cu content is limited to 3.5% or less, preferably 0.5% or more and 2.5% or less.
    [0055] The contents of the constituent chemical elements described above are controlled to be within the ranges described above, in which the relational expressions (1) and (2) low are satisfied.
    Cr + 0.65Ni + 0.60Mo + 0.30W + 0.55Cu - 20C> 19.5 (1) (where Cr, Ni, Mo, W, Cu and C: contents (% by mass) of the chemical elements represented respectively by the corresponding atomic symbols.
    Cr + Mo + 0.50W + 0.30Si-43.5C-0.4Mn-Ni-0.3Cu-9N> 11.5 (2)
    Petition 870190044649, of 05/13/2019, p. 25/49
    16/30 (where Cr, Mo, W, Si, C, Mn, Ni, Cu and N: contents (% by mass) of chemical elements represented respectively by the corresponding atomic symbols). Note that when the values of the left sides of the relational expressions (1) and (2) are calculated, the symbol is assigned a value of 0 in the event that the corresponding chemical element is not contained.
    [0056] Controlling the contents of Cr, Ni, Mo ,. W, Cu and C so that the relational expression (1) is satisfied, there is a significant increase in corrosion resistance (resistance to corrosion by CO2) at a high temperature (up to 230 ° C) in a corrosion environment containing CO2 and Cl - . It is preferable that the value on the left side of the relational expression (1) is 20.0 or more from the point of view of resistance to corrosion at high temperature.
    [0057] Controlling the contents of Cr, Mo, W, Si, C, Mn, Ni, Cu and
    N so that the relational expression (2) is satisfied, there is an increase in the hot work capacity, and work capacity that is required to produce a martensitic stainless steel tube can be achieved. It is preferable that the value on the left side of the relational expression (2) is 12.5 or more.
    [0058] The chemical composition described above is a basic chemical composition and, in addition to the basic chemical composition, one or more elements selected from Nb: 0.2% or less, Ti: 0.3% or less, Zr: 0, 2% or less and B: 0.01% or less and / or Ca: 0.01% or less can be added.
    [0059] One or more elements selected from Nb: 0.2% or less, Ti: 0.3% or less, Zr: 0.2% or less and B: 0.01% or less [0060] Since Nb, Ti, Zr and B are all chemical elements that increase the strength of the steel and increase the resistance to fracture by stress corrosion, one or more elements selected from these chemical elements can be added as needed
    Petition 870190044649, of 05/13/2019, p. 26/49
    17/30 river. It is preferable that the levels of these chemical elements are respectively Nb: 0.02% or more, Ti: 0.04% or more, Zr: 0.02% or more and B: 0.001% or more to achieve these effects. On the other hand, in the case where the levels of these chemical elements are respectively Nb: more than 0.2%, Ti: more than 0.3%, Zr: more than 0.2% and B: more than 0.01% , there is a deterioration in tenacity. Therefore, the levels of these chemical elements are respectively limited to Nb: 0.2% or less, Ti: 0.3% or less, Zr: 0.2% or less and B: -0.01% or less.
    [0061] Ca: 0.01% or less [0062] Since Ca is a chemical element that contributes to the sulfide morphology control function as a result of coalescence of sulfides containing inclusions, Ca can be added as needed. By the coalescence of sulfides containing inclusions, there is a decrease in the distortion of the structure of a matrix in the vicinity of the inclusions in order to obtain an effect of decreasing the ability to trap hydrogen from the inclusions. It is preferable that the Ca content is 0.0005% or more to achieve this effect. On the other hand, in the case where the Ca content is greater than 0.01%, there is an increase in the amount of oxides containing inclusions, which deteriorates the corrosion resistance. Therefore, in the case where Ca is added, it is preferable that the Ca content is 0.01% or less.
    [0063] The rest of the chemical composition different from the chemical constituents described above consists of Fe and the inevitable impurities. As an unavoidable impurity, O: 0.010% or less is acceptable.
    [0064] There is no particular limitation on which method is used to produce a steel tube material. However, it is preferable for molten steel having the specified chemical composition to be melted using a common refining method such as that using a
    Petition 870190044649, of 05/13/2019, p. 27/49
    18/30 steel converter and that the molten steel is transformed into a cast material such as a bar using a conventional casting method such as a continuous casting method. Note that, unlike a continuous casting method, it goes without saying that a casting material such as a bar can be produced using a conventional casting method.
    [0065] In the present invention, a seamless steel tube is produced by heating a steel material having the chemical composition described above, performing the common hot rolling including boring rolling using a laminator method with Mannesmann chuck or a Mannesmann boring mill method, and also performing p cooling to room temperature at a cooling rate equal to or greater than the air cooling rate. Here, the wall thickness of the sewn steel tube is adjusted to be greater than 25.4 mm. Needless to say, the size of the steel material that is the starting material is controlled to be within a suitable range to achieve a seamless steel pipe having such a wall thickness.
    [0066] Heating temperature of a steel material:
    1100 ° C or more and 1300 ° C or less [0067] In the case where the heating temperature of a steel material is less than 1100 ° C, there is an increase in the resistance to deformation due to the heating temperature being excessively low and it is difficult to perform hot rolling because the load on the laminators is too large. On the other hand, in the case where the heating temperature is higher than 1300 ° C, there is a deterioration of the toughness, due to an increase in the diameter of the crystal grain and there is a decrease in the yield due to an increase in the amount of loss by scale. Therefore, it is preferable that the heating temperature of a steel material is 1100 ° C or more and
    Petition 870190044649, of 05/13/2019, p. 28/49
    19/30
    1300 ° C or less, more preferably 1200 ° C or more and 1280 ° C or less.
    [0068] The steel material that has been heated to the heating temperature described above is subjected to hot rolling including boring rolling. Regarding hot rolling, any one of the Mannesmann mandrel rolling mill method, in which the steel material is subjected to processing using a boring rolling mill to perform boring rolling, a subsequent elongation rolling mill, a rolling mill with mandrel and a practical rolling mill, or also a calibrator rolling mill in that order, in which the Mannesmann boring mill method, in which the steel material is subjected to processing using a boring mill to perform boring milling, a subsequent mandrel laminator and a reducing laminator in that order can be used.
    [0069] In the present invention, hot rolling including boring rolling described above is performed under conditions such that the total rolling reduction in a temperature range of 1100 ° C to 900 ° C is 30% or more. By controlling the reduction in rolling in this temperature range to be within a suitable range, the spacing between edges of ferrite-austenite (martensite) grain can be controlled to be small and a decrease in grain diameter can be achieved, which results in an increase in toughness. Even in the case where the lamination reduction is controlled in a temperature range outside the range of 1100 ° C to 900 ° C, if the lamination reduction in the temperature range from 1100 ° C to 900 ° C is outside the appropriate range described above, a decrease in grain diameter according to the present invention cannot be achieved. In the case that the total reduction of lamination in this temperature range is less than 30%. It is difficult to achieve a decrease in
    Petition 870190044649, of 05/13/2019, p. 29/49
    20/30 grain diameter according to the present invention, i.e., it is difficult to control the GSI number of ferrite-austenite (martensite) grain edges per unit length in the direction of the wall thickness to be 120 or more. Therefore, the lamination reduction in the temperature range from 1100 ° C to 900 ° C is adjusted to be 30% or more. With this method, since it is possible to control the spacing between the edges of the ferrite-austenite (martensite) grains to be equal to or less than the specified value, a decrease in the grain diameter can be performed even in the case of a pipe. steel that has a thick wall, which results in an increase in toughness. It is noted that there is no particular limitation in the upper limit of the lamination reduction in this temperature range.
    [0070] In addition, there is no particular limitation on which rolling conditions are used outside the temperature range of 1100 ° C to 900 ° C as long as a seamless steel tube having a specific size and shape can be produced.
    [0071] The seamless steel tube that was produced by performing hot rolling for tube production as described above is subsequently subjected to cooling to room temperature at a cooling rate equal to or greater than the air cooling rate. . In the case of a steel tube having the chemical composition range according to the present invention, a microstructure including a martensite phase as the main phase can be achieved by performing the cooling at a cooling rate equal to or greater than the cooling rate at air.
    [0072] After the tube production has been carried out, the cooled steel tube is subsequently subjected to a heat treatment including quick-quench cooling.
    [0073] In rapid cooling, the steel tube is heated to a heating temperature for rapid cooling of 850C or more
    Petition 870190044649, of 05/13/2019, p. 30/49
    21/30 and 1000 ° C or less, and then cooled with water. In the case where the heating temperature for rapid cooling is less than 850 ° C, the transformation into martensite does not progress sufficiently, and the desired high resistance cannot be achieved. In addition, there is a concern that intermetallic compounds may be formed and toughness and corrosion resistance may deteriorate. On the other hand, in the case where the heating temperature for rapid cooling is greater than 1000 ° C, the fraction of martensite formed becomes excessively high, and the resistance becomes excessively high. Therefore, it is preferable that the heating temperature for rapid cooling is 850 ° C or more and 1000 ° C or less. There is no particular limitation on a retention time when heating is performed for rapid cooling. Meantime. It is preferable that the retention time is 10 to 30 minutes from the point of view of productivity. In addition, it is more preferable that the heating temperature for rapid cooling is 920 ° C more and 980 ° C or less. [0074] After the rapid cooling is performed, the quench is also performed. In tempering, the steel tube is heated to a tempering temperature of 400 ° C or more and 700 ° C or less, and then cooled to a cooling rate equal to or greater than the air cooling rate. In the case where the tempering temperature is less than 400 ° C, a sufficient tempering effect cannot be achieved. On the other hand, in the case where the tempering temperature is higher than 700 ° C, there is a tendency for intermetallic compounds to precipitate, which can deteriorate toughness and corrosion resistance. Therefore, it is preferable that the tempering temperature is 400 ° C or more and 700 ° C or less. Note that there is no particular limitation on the retention time when heating for tempering is performed. However, it is preferable that the retention time is 20 to 60 minutes from the point of view of productivity. Furthermore, it is more preferable that
    Petition 870190044649, of 05/13/2019, p. 31/49
    22/30 tempering temperature is 550 ° C or more and 650 ° C or less.
    [0075] In addition, only the tempering described above can be performed without the execution of rapid cooling in the steel tube that wire subjected to the production of tubes.
    [0076] The seamless steel tube that is produced using the production method described above has a chemical composition described above and a microstructure including a martensite phase as the main phase and a second phase consisting of, by reason of volume, 10 % or more and 60% or less of a ferrite phase and 0% or more and 10% or less of an austenite phase. The steel tube is also a seamless thick high-strength stainless steel tube for tubular oilfield materials having a wall thickness of more than 25.4 mm and having a microstructure in which the GSI value, which is defined as the number of ferritemartensite grain edges per unit length of a line segment drawn in the direction of the wall thickness, is 120 or more in the central portion in the direction of the wall thickness.
    [0077] In the present invention, the microstructure includes a martensite phase as the main phase and a second phase consisting of, by reason of volume, 10% or more and 60% or less of a ferrite phase and 0% or more and 10% or less than an austenite phase to achieve the desired high strength.
    [0078] In the case where the volume ratio of a ferrite phase is less than 10%, there is a deterioration of the hot forming capacity. On the other hand, in the case where the volume ratio of a phase stinks a phase stinks a ferrite phase is greater than 60%, there is a deterioration in strength and toughness. In addition, although the second phase may include 10% or less of an austenite phase other than a ferrite phase, it is preferable that the volume ratio of an austenite phase is as small as possible, including 0%, to achieve
    Petition 870190044649, of 05/13/2019, p. 32/49
    23/30 sufficient strength. In the case where the volume ratio of an austenite phase is greater than 10%, it is difficult to achieve the desired high resistance.
    [0079] The steel tube according to the present invention has a microstructure including a martensite phase and a ferrite phase, and, in addition, an austenite phase retained as described above, in which a GSI value, which is defined as the number of edges of ferrite-martensite grains per unit length of a line segment drawn in the direction of the wall thickness is 120 or more in the central portion in the direction of the wall thickness. In the case where the GSI value is less than 120, since it is difficult to achieve a decrease in the grain diameter of a microstructure, it is difficult to achieve the desired toughness stably.
    [0080] Note that a GSI value (line / mm) is a value that can be determined by counting the number (lines / mm) of ferrite-martensite grain edges in the direction of the wall thickness using a photograph of the microstructure taken by observing a sample that has been etched with a Vilella reagent, using an optical microscope (magnification 100 to 1000 times).
    [0081] Hereinafter the present invention will also be described on the basis of Examples.
    EXAMPLES [0082] Cast steels having the chemical compositions given in
    Table 1 were cast using a steel converter, and then cast bars (steel materials having an outside diameter of 260 mm) using a continuous casting method. The steel materials obtained were heated to the temperatures given in Table 2, and then transformed into seamless steel tubes (having an external diameter of 168.3 to 297 mm and a wall thickness of 26 to 34 mm) by carrying out the rolling hot using a la method
    Petition 870190044649, of 05/13/2019, p. 33/49
    24/30 mining of Mannesmann chuck rolling in which the steel material is subjected to hot processing using a common boring rolling method, an elongation rolling mill, a mandrel rolling mill, and a practical rolling mill, or calibrator laminator in that order under conditions such that the reduction of lamination in a temperature range of 1100 ° C to 900 ° C satisfied the conditions given in Table 2. In addition, after hot rolling was performed, cooling was performed under the conditions given in Table 2. The seamless steel tubes obtained were subjected to quick-quenching under the conditions given in Table 2.
    [0083] Using specimens cut from the steel tubes obtained, a microstructure was observed, and tensile, toughness and corrosion resistance properties were investigated. Investigation methods will be described hereinafter.
    Observation of the Microstructure [0084] Using a specimen to observe the microstructure cut from the central portion in the direction of the wall thickness of the steel tube obtained, a microstructure in a cross section in the direction of the wall thickness that has been polished and etched with a vilella reagent, it was observed using an optical microscope (at a magnification of 100 to 1000 times). Using the photograph taken, the types of microstructures were identified, and the fraction (volume ratio) of a ferrite phase was calculated by performing image analysis.
    [0085] Here, that of the austenite phase (γ) was determined using an X-ray diffraction method. The integrated intensities of refracted X-rays for the plane (220) of a phase (γ) and the plane (211) ferrite phase (a) were determined, and the conversion was performed using the following execution:
    Petition 870190044649, of 05/13/2019, p. 34/49
    25/30 (volume ratio) = 100 / (1 + (laRy / lyRa)) where [0086] la: integrated intensity of a phase α [0087] ly: integrated intensity of a phase γ [0088] Ra: calculated value theoretically of α in the crystallography base [0089] Ry: theoretically calculated value of γ in the crystallography base [0090] Here, the phase fraction of a martensite phase was derived as a different remainder of these phases.
    [0091] In addition, the specimen for observation of the microstructure was etched with a Vilella reagent and observed using an optical microscope (at 400 times magnification). Using the photograph taken, the number (lines / mm) of ferritemartensite grain edges was counted in the direction of the wall thickness to calculate the GSI value.
    Tensile properties [0092] A specimen specified by the API standard (having a useful length of 50.8 mm) was cut from the central portion in the direction of the wall thickness of the steel tubes obtained according to the API standard so that the pull direction is the direction of the tube axis. By performing a tensile test based on the API standard, tensile properties (yield strength YS, tensile strength TS, and elongation El) were determined.
    (3) Tenacity [0093] Using a specimen with a V-notch (having a thickness of 10 mm) that was cut from the central portion in the direction of the wall thickness of the steel tube obtained according to the ISO standard of so that the longitudinal direction of the specimen was the circumferential direction of the tube, a Charpy impact test was performed
    Petition 870190044649, of 05/13/2019, p. 35/49
    26/30 under a condition of a test temperature of -10 ° C to determine the energy absorbed vE-10 (J). Here the number of specimens was 3 for each steel tube, the average value of the three was used as the value for the steel tube.
    (4) Corrosion resistance [0094] A specimen for a corrosion test (having a thickness of 3 mm, a width of 25 mm, and a length of 50 mm) was cut from the central portion in the direction of the wall thickness of the steel tube obtained and used for a corrosion test.
    [0095] In the corrosion test, the specimen was immersed in a 20% aqueous solution of NaCl (having a temperature of 230 ° C with 3.0 MPa dioxide gas being dissolved in the saturated state) that was contained in the autoclave , for 14 days. After the corrosion test was performed, determining the weight of the specimen, the corrosion rate was calculated from the decrease in weight. In addition, after the corrosion test was performed, the specimen was observed using a magnifying glass at a magnification rate of 50 times to observe whether localized corrosion occurred or not. A case in which localized corrosion with a diameter of 0.2 mm or more was observed was evaluated as a case in which localized corrosion occurred.
    [0096] The results obtained are shown in Table 3.
    Petition 870190044649, of 05/13/2019, p. 36/49
    Table 1
    Steel No. Chemical composition (% by mass) Note Ç Si Mn P s Cr Ni V Al N O Mo, W, Cu Nb, Ti, Zr, B Here Value on the right side of the relational expression (1) *) Satisfaction of relational expression(1) Value on the right side of the relational expression (2) **) Satisfaction of relational expression(2) THE 0.026 0.2 0.24 0.01 0.001 16.7 4.11 0.027 0.02 0.051 0.0025 Mo: 2.13W: 1.05Cu: 0.51 Nb: 0.04320.73 Yes 13.47 Yes Ex. B 0.019 0.18 0.49 0.01 0.001 17 3.88 0.045 0.02 0.049 0.0033 Mo: 2.59 20.7 Yes 14.3 Yes Ex. Ç 0.034 0.26 0.77 0.01 0.001 17.2 4.31 0.036 0.02 0.057 0.029 Mo: 2.34Cu: 0.56 Nb: 0.035Ti: 0.075 Zr: 0.0087 B: 0.001321.33 Yes 12.84 Yes Ex. D 0.023 0.33 0.66 0.01 0.001 16.1 3.59 0.054 0.02 0.047 0.0041 Mo: 2.01 W: 1.21Cu: 2.02 Ti: 0.07620.65 Yes 12.95 Yes Ex. AND 0.018 0.23 0.31 0.02 0.001 17.5 4 0.046 0.01 0.05 0.0019 Mo: 2.40Cu: 0.75 Nb: 0.04421.59 Yes 14.39 Yes Ex. F 0.012 0.27 0.45 0.02 0.001 16.7 2.6 0.46 0.01 0.056 0.0028 Mo: 1.90 19.29 No 14.83 Yes Ex.Comp. G 0.035 0.28 0.39 0.02 0.001 16.1 4.6 0.043 0.02 0.042 0.0024 Cu: 0.62 Ti: 0.02519.87 Yes 11.24 No Ex.Comp.
    *) Cr + 0.65Ni + 0.60Mo + 0.30W + 0.55Cu - 20C> 19.5 (1) **) Cr + Mo + 0.50W + 0.30Si - 43.5C - 0.4Mn - Ni - 0.3Cu-9N> 11.5 (2)
    Underlined value is out of range according to the present invention
    27/30
    Petition 870190044649, of 05/13/2019, p. 37/49
    Table 2
    Steel tube Steel No. Hot rolling Seamless steel tube Heat treatment Note Heating temperature (° C) Lamination reduction from 1100 ° C to 900 ° C(%) Hot rolling method *) Cooling after tube production Size (outside diameter in mm of wall thickness in mm) Quick cooling Hardening Heating temperature (° C) Retention time (min) Cooling Cooling stop temperature (° C) Heating temperature (° C) Retention time (min) 1 THE 1250 21 The cool. the water 297φχ34 960 30 cool. the water 25 620 60 Ex. Comp. 2 THE 1250 26 The cool. the water 297φχ 34 960 30 cool. the water 25 620 60 Ex. Comp. 3 THE 1250 34 The cool. the water 297φχ 34 960 30 cool. the water 25 620 60 Example 4 THE 1250 40 The cool. the water 297φχ 34 960 30 cool. the water 25 620 60 Example 5 THE 1250 38 The cool. the water 297φχ26 960 30 cool. the water 25 620 60 Example 6 THE 1250 45 The cool. the water 297φχ26 960 30 cool. the water 25 620 60 Example 7 B 1250 23 The cool. the water 297φχ32 1000 30 cool. the water 25 630 60 Ex. Comp. 8 B 1250 29 The cool. the water 297φχ32 1000 30 cool. the water 25 630 60 Ex. Comp. 9 B 1250 33 The cool. the water 297φχ32 1000 30 cool. the water 25 630 60 Example 10 B 1250 37 The cool. the water 297φχ32 1000 30 cool. the water 25 630 60 Example 11 Ç 1260 35 The cool. the water 297φχ32 980 30 cool. the water 25 600 60 Example 12 Ç 1260 40 B cool. the water 297φχ26 980 30 cool. the water 25 600 60 Example 13 D 1240 33 The cool. the water 297φχ32 980 30 cool. the water 25 600 60 Example 14 AND 1240 36 The cool. the water 297φχ32 980 30 cool. the water 25 590 60 Example 15 AND 1240 32 B cool. the water 297φχ26 980 30 cool. the water 25 600 60 Example 16 AND 1240 28 The cool. the water 297φχ32 980 30 cool. the water 25 610 60 Reference example 17 AND 1240 33 The cool. the water 297φχ32 980 30 cool. the water 25 610 60 Example 18 F 1240 35 The cool. the water 297φχ32 980 30 cool. the water 25 600 60 Ex. Comp. 19 G 1360 34 The cool. the water 297φχ26 980 30 cool. the water 25 600 60 Ex. Comp.
    *) a: Mannesmann boring mill method; b: Mannesmann boring mill method
    28/30
    Petition 870190044649, of 05/13/2019, p. 38/49
    Table 3
    Steel Tube No. Steel No. Microstructure Traction property Tenacity Corrosion resistance Note Type* M F γ GSI YS TS El VE-10 (J) Corrosion rate (mm / year) Existence of localized corrosion % by volume % by volume % by volume lines / mm MPa MPa % 1 THE M + F + γ 58 35 7 88 812 987 25.4 25 0.105 No Comparative Example 2 THE M + F + γ 58 34 8 113 833 974 23 38 0.098 No Comparative Example 3 THE M + F + γ 59 33 8 131 786 913 24.1 62 0.102 No Example 4 THE M + F + γ 55 37 8 145 823 952 22.8 105 0.978 No Example 5 THE M + F + γ 57 38 5 182 811 965 23.4 145 0.965 No Example 6 THE M + F + γ 59 33 8 194 798 987 24.4 152 0.104 No Example 7 B M + F + γ 63 29 8 79 799 944 24.1 23 0.108 No Comparative Example 8 B M + F + γ 55 39 6 105 783 916 23.6 32 0.093 No Comparative Example 9 B M + F + γ 57 41 2 132 800 933 21.5 82 0.078 No Example 10 B M + F + γ 60 32 8 140 812 945 25.4 125 0.069 No Example 11 Ç M + F + γ 65 28 7 135 868 1025 22.9 45 0.099 No Example 12 Ç M + F + γ 62 31 7 142 876 1033 22 79 0.087 No Example 13 D M + F + γ 59 36 5 136 796 987 23.2 84 0.082 No Example 14 AND M + F + γ 59 33 8 140 823 976 24.4 105 0.093 No Example 15 AND M + F + γ 61 33 6 133 856 1001 23 55 0.103 No Example 16 AND M + F + γ 59 33 8 137 889 1052 23.5 69 0.11 No Reference example 17 AND M + F + γ 61 31 8 141 901 1085 23.2 89 0.09 No Example 18 F M + F + γ 47 49 4 132 812 974 24.9 29 0.101 No Comparative Example 19 G M + F + γ 62 31 7 135 796 966 23.9 65 0.179 Yes Comparative Example
    *) M: martensite, F: ferrite, γ: austenite
    Underlined values are outside the range of the present invention
    29/30
    Petition 870190044649, of 05/13/2019, p. 39/49
    30/30 [0097] All examples of the present invention had a high strength of 758 MPa (110 ksi) or more and a high toughness of vE10 (J): 40 J or more despite having a large wall thickness. In addition, even in the environment of intense corrosion having a high temperature and containing CO2 and Cl - , the decrease in weight due to corrosion was 0.127 mm / year or less and localized corrosion did not occur, which means that these steel tubes were excellent in terms of corrosion resistance.
    [0098] On the other hand, in the case of comparative examples that were outside the range according to the present invention, it corresponded to one or more of a case in which the desired high resistance was not achieved, a case in which the GSI value was less than 120 and vE-10 (J) was less than 40 J, which means high toughness was not achieved stably, and a case in which a decrease in weight due to corrosion was greater than 0.127 mm / year, which means that there was a deterioration in corrosion resistance.
    Petition 870190044649, of 05/13/2019, p. 40/49
    权利要求:
    Claims (6)
    [1]
    1/4
    1. Method for producing a seamless high-strength stainless steel tube for tubular materials for oil fields having a wall thickness of more than 25.4 mm, the method characterized by the fact that it comprises heating a steel material; hot rolling, including boring rolling, the steel material in a seamless steel tube; and cooling the seamless steel tube at a cooling rate equal to or greater than the air cooling rate, the steel material having a chemical composition containing, in mass%,
    C: 0.005% or more and 0.06% or less,
    Si: 0.05% or more and 0.5% or less,
    Mn: 0.2% or more and 1.8% or less,
    P: 0.03% or less,
    S: 0.005% or less,
    Cr: 15.5% or more and 18.0% or less,
    Ni: 1.5% or more and 4.5% or less,
    V: 0.02% or more and 0.2% or less,
    Al: 0.002% or more and 0.05% or less,
    N: 0.01% or more and 0.15% or less,
    O: 0.006% or less, and also containing one, two or more elements selected from among
    Mo: 1.0% or more and 3.5% or less,
    W: 3.0% or less, and
    Cu: 3.5% or less, and the balance being Fe and the inevitable impurities, where the relational expressions (1) and (2) below are satisfied, hot rolling, including boring rolling, is performed under conditions such that the total reduction of lamination in a tempera range
    Petition 870190044649, of 05/13/2019, p. 41/49
    [2]
    2/4 temperatures from 1100 ° C to 900 ° C are 30% or more, and after the rolled steel tube is cooled to room temperature, quick-quench or quench is performed:
    Cr + 0.65Ni + 0.60Mo + 0.30W + 0.55Cu - 20C> 19.5 (1)
    Cr + Mo + 0.50W + 0.30Si - 43.5C - 0.4Mn - Ni - 0.3Cu 9N> 11.5 (2) where Cr, Mo, W, Si, C, Mn, Ni, Cu and N: contents (% by mass) of the chemical elements represented by the corresponding atomic symbols respectively.
    2. Method for producing a seamless high-strength stainless steel tube for tubular materials for oil fields according to claim 1, characterized by the fact that the chemical composition also contains, in mass%, one or more elements selected from Nb: 0.2% or less, Ti: 0.3% or less, Zr: 0.2% or less and B: 0.01% or less.
    [3]
    3. Method for producing a seamless, high-strength stainless steel tube for tubular materials for oil fields according to claim 1 or 2, characterized by the fact that the chemical composition also contains, in mass%,
    Ca: 0.01% or less.
    [4]
    4. High-strength seamless stainless steel tube for tubular materials for oil fields produced by the method as defined in any of claims 1 to 3, characterized by the fact that it has a wall thickness of more than 25.4 mm, the steel tube having a chemical composition containing, in% by mass,
    C: 0.005% or more and 0.06% or less,
    Si: 0.05% or more and 0.5% or less,
    Mn: 0.2% or more and 1.8% or less,
    P: 0.03% or less,
    Petition 870190044649, of 05/13/2019, p. 42/49
    3/4
    S: 0.005% or less,
    Cr: 15.5% or more and 18.0% or less,
    Ni: 1.5% or more and 4.5% or less,
    V: 0.02% or more and 0.2% or less,
    Al: 0.002% or more and 0.05% or less,
    N: 0.01% or more and 0.15% or less,
    O: 0.006% or less, and also containing one, two or more elements selected from among
    Mo: 1.0% or more and 3.5% or less,
    W: 3.0% or less, and
    Cu: 3.5% or less, and the balance being Fe and the inevitable impurities, in which the relational expressions (1) and (2) below are satisfied, having a microstructure including a martensite phase as the main phase and a second phase consisting in, by volume, 10% or more and 41% or less of a ferrite phase and 0% or more and 10% or less of an austenite phase, in which the GSI value, which is defined as the number of edges of ferrite-martensite grains per unit length of a line segment drawn in the direction of wall thickness, is 120 or more in the central portion in the direction of the pipe thickness, and having excellent low temperature toughness and excellent corrosion resistance:
    Cr + 0.65Ni + 0.60Mo + 0.30W + 0.55Cu - 20C> 19.5 (1)
    Cr + Mo + 0.50W + 0.30Si - 43.5C - 0.4Mn - Ni - 0.3Cu 9N> 11.5 (2) where Cr, Mo, W, Si, C, Mn, Ni, Cu and N: contents (% by mass) of the chemical elements represented respectively by the corresponding atomic symbols, in which, in the technical characteristic of excellent toughness at low temperature, the test temperature refers to the toughness of
    Petition 870190044649, of 05/13/2019, p. 43/49
    4/4
    40J or more in terms of energy absorbed vE-10 determined by conducting a Charpy impact test at a temperature of -10 o C, in which, in the technical characteristic of excellent corrosion resistance, in an environment of intense corrosion at a high temperature of 230 o C or more and containing CO2 and Cl - , a reduction in weight due to corrosion is 0.127 mm / year or less and localized corrosion does not occur.
    [5]
    5. High strength seamless stainless steel tube for tubular materials for oil fields according to claim 4, characterized by the fact that the chemical composition also contains, in mass%, one or more elements selected from among
    Nb: 0.2% or less,
    Ti: 0.3% or less,
    Zr: 0.2% or less, and
    B: 0.01% or less.
    [6]
    6. High strength seamless stainless steel tube for tubular materials for oil fields according to claim 4 or 5, characterized by the fact that the chemical composition also contains, in mass%,
    类似技术:
    公开号 | 公开日 | 专利标题
    BR112014029392B1|2019-09-24|HIGH-RESISTANT STAINLESS STEEL PIPE FOR TUBULAR FIELD MATERIALS AND METHOD FOR PRODUCTION
    US10151011B2|2018-12-11|High-strength stainless steel seamless tube or pipe for oil country tubular goods, and method of manufacturing the same
    US9758850B2|2017-09-12|High strength stainless steel seamless pipe with excellent corrosion resistance for oil well and method of manufacturing the same
    BR112016027036B1|2021-04-13|HIGH RESISTANCE SEAMLESS STAINLESS STEEL TUBE FOR TUBULAR ARTICLES IN THE OIL FIELD AND METHOD FOR MANUFACTURING THE SAME
    BR112014030346B1|2020-05-05|tubular materials from oil fields and production methods
    BR112014017204B1|2019-04-02|STAINLESS STEEL FOR OIL WELLS AND STAINLESS STEEL PIPES FOR OIL WELLS
    BR112017009762B1|2021-09-08|LOW ALLOY STEEL OIL WELL TUBE AND LOW ALLOY STEEL OIL WELL TUBE MANUFACTURING METHOD
    BR112017004534B1|2021-05-04|high strength seamless steel tube for tubular products for the oil industry and manufacturing method of the same
    BR112020003067A2|2020-08-25|seamless tube of high strength stainless steel for tubular petroleum products in the country, and process for manufacturing it
    BR112016000543B1|2020-11-17|low alloy oil well steel pipe and method for making the same
    BRPI1014949B1|2020-06-02|STAINLESS STEEL FOR OIL WELL, STAINLESS STEEL TUBE FOR OIL WELL, AND METHOD OF MANUFACTURING STAINLESS STEEL FOR OIL WELL.
    BR112012024756B1|2018-09-25|high strength stainless steel for oil well and tube high strength stainless steel for oil well
    BR112014019065B1|2019-03-26|METHOD FOR PRODUCING A RESISTANT STRENGTH RESISTANT STRENGTH STEEL MATERIAL
    BR102014005015A2|2016-02-16|martensitic-ferritic stainless steel, manufactured product, process for producing forged parts or bars or blades of martensitic-ferritic stainless steel and process for producing all seamless martensitic-ferritic stainless steel
    BR112019017764A2|2020-03-31|MARTENSITIC STAINLESS STEEL PRODUCT
    JP5804232B1|2015-11-04|Martensitic Cr-containing steel and steel pipe for oil well
    EP2947167A1|2015-11-25|Stainless steel seamless tube for use in oil well and manufacturing process therefor
    ES2719981T3|2019-07-17|High strength steel material for oil wells and tubular oilfield products
    BR112013020445B1|2019-08-13|duplex stainless steel and production method for the same
    BR112017006937B1|2021-05-04|low alloy steel pipe for oil well
    JP6372070B2|2018-08-15|Ferritic / martensitic duplex steel and oil well steel pipe
    US11193179B2|2021-12-07|Seamless stainless steel pipe for oil country tubular goods and method of manufacturing the same
    BR112013022812B1|2019-01-22|duplex stainless steel
    BRPI0609856A2|2010-05-11|stainless steel pipe having excellent swelling capacity for oilfield tubular products
    BR112015031596B1|2020-03-03|SEAMLESS STEEL TUBE FOR IN-LINE TUBE USED IN ACRYLIC ENVIRONMENTS
    同族专利:
    公开号 | 公开日
    RU2584100C1|2016-05-20|
    US20150101711A1|2015-04-16|
    BR112014029392A2|2017-06-27|
    EP2857530B1|2018-12-12|
    CA2872342C|2018-07-17|
    WO2013179667A1|2013-12-05|
    CA2872342A1|2013-12-05|
    EP2857530A4|2015-11-04|
    CN104379774A|2015-02-25|
    AU2013268908A1|2014-11-20|
    IN2014KN02395A|2015-05-01|
    EP2857530A1|2015-04-08|
    ES2708275T3|2019-04-09|
    JP2013249516A|2013-12-12|
    JP5488643B2|2014-05-14|
    CN104379774B|2017-04-26|
    AU2013268908B2|2016-01-28|
    引用文献:
    公开号 | 申请日 | 公开日 | 申请人 | 专利标题
    JPS5711927B2|1976-06-14|1982-03-08|
    JP5109222B2|2003-08-19|2012-12-26|Ｊｆｅスチール株式会社|High strength stainless steel seamless steel pipe for oil well with excellent corrosion resistance and method for producing the same|
    CN100497705C|2003-10-31|2009-06-10|杰富意钢铁株式会社|High strength stainless steel pipe for line pipe excellent in corrosion resistance and method for production thereof|
    US7862666B2|2003-10-31|2011-01-04|Jfe Steel Corporation|Highly anticorrosive high strength stainless steel pipe for linepipe and method for manufacturing same|
    JP4462005B2|2003-10-31|2010-05-12|Ｊｆｅスチール株式会社|High strength stainless steel pipe for line pipe with excellent corrosion resistance and method for producing the same|
    JP4792778B2|2005-03-29|2011-10-12|住友金属工業株式会社|Manufacturing method of thick-walled seamless steel pipe for line pipe|
    CN1840731A|2005-03-31|2006-10-04|住友金属工业株式会社|Method for manufacturing seamless steel pipe for mechanical parts|
    JP4635764B2|2005-07-25|2011-02-23|住友金属工業株式会社|Seamless steel pipe manufacturing method|
    JP4893196B2|2006-09-28|2012-03-07|Ｊｆｅスチール株式会社|High strength stainless steel pipe for oil well with high toughness and excellent corrosion resistance|
    ES2674255T3|2008-03-28|2018-06-28|Nippon Steel & Sumitomo Metal Corporation|Stainless steel for use in oil well tube|
    AR073884A1|2008-10-30|2010-12-09|Sumitomo Metal Ind|STAINLESS STEEL TUBE OF HIGH RESISTANCE EXCELLENT IN RESISTANCE TO FISURATION UNDER VOLTAGE SULFURS AND CORROSION OF GAS OF CARBONIC ACID IN HIGH TEMPERATURE.|
    US8778928B2|2009-01-26|2014-07-15|Danpet Ab|Indolyl-oxadiazolyl-diazabicyclononane derivatives and their medical and diagnostical use|
    AR076669A1|2009-05-18|2011-06-29|Sumitomo Metal Ind|STAINLESS STEEL FOR PETROLEUM WELLS, STAINLESS STEEL TUBE FOR PETROLEUM WELLS, AND STAINLESS STEEL MANUFACTURING METHOD FOR PETROLEUM WELLS|
    BR112012002024B1|2009-08-21|2019-01-29|Nippon Steel & Sumitomo Metal Corporation|Thick wall seamless steel tube manufacturing method.|
    MX2012012435A|2010-04-28|2013-03-05|Nippon Steel & Sumitomo Metal Corp|High-strength stainless steel for oil well and high-strength stainless steel pipe for oil well.|JP5967066B2|2012-12-21|2016-08-10|Ｊｆｅスチール株式会社|High strength stainless steel seamless steel pipe for oil well with excellent corrosion resistance and method for producing the same|
    KR101554787B1|2013-12-24|2015-09-21|주식회사 포스코|Super duplex stainless steel having an excellent corrosion resistance and hot workability|
    CN103966525B|2014-05-21|2016-05-11|攀钢集团江油长城特殊钢有限公司|A kind of chromium high molybdenum high ferritic stainless steel seamless tubular goods and manufacture method thereof|
    CN105463562A|2014-09-05|2016-04-06|上海金保莱不锈钢有限公司|Manufacturing method for seamless stainless steel pipe resistant to corrosion of anions|
    WO2016079922A1|2014-11-18|2016-05-26|Ｊｆｅスチール株式会社|Method for producing high-strength stainless steel seamless pipe for oil wells|
    JP6237873B2|2014-11-19|2017-11-29|Ｊｆｅスチール株式会社|High strength stainless steel seamless steel pipe for oil well|
    MX2017006869A|2014-11-27|2017-08-14|Jfe Steel Corp|Device array for manufacturing seamless steel pipe or tube and manufacturing method for duplex stainless steel seamless pipe or tube using same.|
    WO2016113794A1|2015-01-15|2016-07-21|Ｊｆｅスチール株式会社|Seamless stainless steel pipe for oil well, and method for manufacturing same|
    JP6202010B2|2015-01-16|2017-09-27|Ｊｆｅスチール株式会社|Manufacturing method of high-strength duplex stainless steel seamless steel pipe|
    JP6206423B2|2015-01-22|2017-10-04|Ｊｆｅスチール株式会社|High strength stainless steel plate excellent in low temperature toughness and method for producing the same|
    JP6292142B2|2015-02-06|2018-03-14|Ｊｆｅスチール株式会社|Manufacturing method of high strength stainless steel seamless steel pipe for oil well|
    EP3260564A4|2015-02-20|2017-12-27|JFE Steel Corporation|High-strength seamless thick-walled steel pipe and process for producing same|
    JP6341125B2|2015-03-17|2018-06-13|Ｊｆｅスチール株式会社|Method for producing duplex stainless steel pipe|
    JP6341181B2|2015-03-25|2018-06-13|Ｊｆｅスチール株式会社|Method for producing duplex stainless steel seamless pipe|
    BR112018000540A2|2015-07-10|2018-09-18|Jfe Steel Corp|high strength seamless stainless steel tube and method for manufacturing high strength seamless stainless steel tube|
    CA2980889C|2015-08-04|2020-02-25|Nippon Steel & Sumitomo Metal Corporation|Stainless steel and stainless steel product for oil well|
    JP6686320B2|2015-08-05|2020-04-22|日本製鉄株式会社|Manufacturing method of stainless steel pipe|
    JP6515340B2|2015-08-18|2019-05-22|日本製鉄株式会社|Oil well tube|
    JP6409827B2|2015-08-18|2018-10-24|Ｊｆｅスチール株式会社|Manufacturing method of seamless stainless steel pipe for oil well|
    EP3385403B1|2016-02-08|2020-01-01|JFE Steel Corporation|High-strength seamless stainless steel pipe for oil country tubular goods and method of manufacturinghigh-strength seamless stainless steel pipe|
    JP6156609B1|2016-02-08|2017-07-05|Ｊｆｅスチール株式会社|High strength stainless steel seamless steel pipe for oil well and method for producing the same|
    WO2018020886A1|2016-07-27|2018-02-01|Ｊｆｅスチール株式会社|High strength seamless stainless steel pipe for oil wells and production method therefor|
    CN106399865A|2016-11-17|2017-02-15|无锡明盛纺织机械有限公司|High-temperature-resistant and abrasion-resistant material for circulating fluidized bed boiler|
    CN110312816A|2017-02-24|2019-10-08|杰富意钢铁株式会社|Oil well high-strength stainless steel seamless steel tube and its manufacturing method|
    EP3604591A4|2017-03-28|2020-09-02|Nippon Steel Corporation|Martensitic stainless steel material|
    CN107433428A|2017-08-22|2017-12-05|苏州双金实业有限公司|A kind of processing method of stainless-steel pipe easy to operate|
    BR112021000039A2|2018-07-09|2021-03-30|Nippon Steel Corporation|SEAMLESS STEEL TUBE AND METHOD FOR ITS PRODUCTION|
    法律状态:
    2019-02-12| B07A| Application suspended after technical examination (opinion) [chapter 7.1 patent gazette]|
    2019-07-30| B09A| Decision: intention to grant [chapter 9.1 patent gazette]|
    优先权:
    申请号 | 申请日 | 专利标题
    JP2012-125126|2012-05-31|
    JP2012125126A|JP5488643B2|2012-05-31|2012-05-31|High strength stainless steel seamless pipe for oil country tubular goods and method for producing the same|
    PCT/JP2013/003411|WO2013179667A1|2012-05-31|2013-05-30|High-strength stainless steel seamless pipe for use as oil well piping, and manufacturing method therefor|
    [返回顶部]