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WO2016079922A1 - Procédé de fabrication de tube sans soudure haute résistance en acier inoxydable pour puits de pétrole - Google Patents

Procédé de fabrication de tube sans soudure haute résistance en acier inoxydable pour puits de pétrole Download PDF

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Publication number
WO2016079922A1
WO2016079922A1 PCT/JP2015/005248 JP2015005248W WO2016079922A1 WO 2016079922 A1 WO2016079922 A1 WO 2016079922A1 JP 2015005248 W JP2015005248 W JP 2015005248W WO 2016079922 A1 WO2016079922 A1 WO 2016079922A1
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Prior art keywords
less
steel pipe
temperature
heating
seamless
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English (en)
Japanese (ja)
Inventor
鈴木　健史
江口　健一郎
石黒　康英
俊輔 佐々木
裕己 牛田
城吾 後藤
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JFE Steel Corp
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JFE Steel Corp
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Priority to JP2016503262A priority Critical patent/JP6315076B2/ja
Publication of WO2016079922A1 publication Critical patent/WO2016079922A1/fr
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    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
    • C21D8/10—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of tubular bodies
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D9/00—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
    • C21D9/08—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for tubular bodies or pipes
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
    • C22C38/58—Ferrous alloys, e.g. steel alloys containing chromium with nickel with more than 1.5% by weight of manganese

Definitions

  • the present invention relates to a seamless steel pipe for oil wells that contains carbon dioxide (CO 2 ), chlorine ions (Cl ⁇ ), etc., and is suitable for use in oil wells and gas wells in extremely severe corrosive environments.
  • the present invention relates to a method for producing a high-strength stainless steel seamless pipe for oil wells, which has both excellent corrosion resistance and excellent low-temperature toughness.
  • Patent Document 1 describes a high-strength stainless steel pipe for oil wells excellent in corrosion resistance and a method for producing the same.
  • Cool to room temperature at a cooling rate to obtain a seamless steel pipe of the specified dimensions then reheat the seamless steel pipe to a temperature of 850 ° C or higher, then cool to 100 ° C or lower at a cooling rate of air cooling or higher, and then lower to 700 ° C or lower. It is characterized by a quenching and tempering treatment that is heated to a temperature.
  • This high-strength stainless steel seamless pipe has a structure with a ferrite phase of 10-60% by volume and the balance being a martensite phase, yield strength: high strength of 654 MPa or more, CO 2 and Cl ⁇
  • it has sufficient corrosion resistance even in severe corrosive environments up to 230 ° C, and has high toughness with absorbed energy at -40 ° C of Charpy impact test of 50J or more.
  • Japanese Patent No. 5109222 Japanese Patent Laid-Open No. 2005-336595
  • ferrite grains can be divided and refined by hot working. However, with thick materials, even if hot working is performed, it is difficult to impart sufficient strain to the center of the wall thickness, so ferrite grains cannot be separated at the center of the wall thickness. The coarsening of the ferrite grains may also occur by cooling after cold rolling. Coarse ferrite grains, particularly connected coarse ferrite grains, tend to be a propagation path for brittle cracks. For this reason, for example, in a steel pipe rolled at a high temperature with a high fraction of ferrite phase, in particular, a structure containing coarse ferrite grains is formed at the center of the thickness, and the toughness is often lowered. Further, when the ferrite grains become coarse, the strength is also affected, and in particular, the yield strength may be reduced.
  • Patent Document 1 does not mention temperature control during high-temperature heating or hot working of the material, and the temperature during high-temperature heating or hot working of the material affects the low-temperature toughness of the stainless steel seamless pipe. There is no mention of the impact.
  • the seamless steel pipe targeted by the technology described in Patent Document 1 is a steel pipe having a wall thickness of up to 12.7 mm at the most. Therefore, Patent Document 1 describes a thick steel pipe having a wall thickness exceeding 13 mm. There is no mention until.
  • An object of the present invention is to provide a method for producing a high-strength stainless steel seamless pipe for oil wells that has high strength, excellent corrosion resistance, and excellent low-temperature toughness. .
  • high strength refers to the case where the yield strength YS: 654 MPa (95 ksi) or higher is maintained, and “excellent low temperature toughness” refers to the Charpy impact test in accordance with JIS Z 2242. Test temperature: Absorption energy at -40 ° C vE -40 means 50J or more.
  • excellent corrosion resistance refers to a test solution held in an autoclave: 20% by mass NaCl aqueous solution (liquid temperature: 230 ° C, 100 atm CO 2 gas atmosphere).
  • the corrosion rate when the immersion time is 7 days (168 hours) is less than 0.12 mm / y.
  • the present inventors diligently studied various factors affecting the low-temperature toughness of a high-strength stainless steel seamless pipe having a ferrite-martensite two-phase structure.
  • the refinement of the ferrite phase is the most effective means for improving the low temperature toughness.
  • a steel pipe material adjusted to a predetermined composition is usually heated to a predetermined heating temperature range, Perform hot working.
  • the steel pipe material exhibits a structure composed of two phases of ferrite and austenite, but as the heating temperature rises, the fraction of the ferrite phase increases.
  • the ferrite grains are likely to grow rapidly and become coarse ferrite grains by being held at a high temperature for a long time. When coarse ferrite grains are formed, the low temperature toughness decreases.
  • the present inventors have further studied a measure for preventing the formation of the coarse ferrite grains. As a result, it has been found that when the austenite phase fraction is heated to a temperature range where the volume fraction is less than 10%, the growth rate of ferrite grains starts to increase rapidly. Based on this knowledge, the present inventors, in the heating process in the production of seamless steel pipes, if the austenite phase fraction is heated in a temperature range where the volume fraction is 10% or more, the grain growth of the ferrite grains during heating It was found that can be suppressed.
  • the above-mentioned heating is applied in all heating processes in the production of seamless steel pipes, and the growth of ferrite grains during heating can be suppressed, the ferrite grains can be divided and refined in the subsequent hot rolling process, and the structure becomes finer It was found that can be easily achieved.
  • the present invention has been completed on the basis of such findings and further studies. That is, the gist of the present invention is as follows. (1) A steel pipe material processing step in which a steel material is heated and hot-worked to form a steel pipe material, and a hot-working step in which the steel pipe material is heated, piped, formed, and made into a seamless steel pipe, A heat treatment step for performing heat treatment on the seamless steel pipe, and a method for producing the seamless steel pipe,
  • the steel material is mass%, C: 0.005 to 0.05%, Si: 0.05 to 0.5%, Mn: 0.2 to 1.8%, P: 0.03% or less, S: 0.005% or less, Cr: 15.5 to 18.0%, Ni : 1.5 to 5.0%, Mo: 1.0 to 3.5%, V: 0.02 to 0.2%, Al: 0.001 to 0.050%, N: 0.001 to 0.15%, O: 0.006% or less, the following formula (1) and the following (2 ) Formula Cr + 0.65Ni + 0.6Mo + 0.55Cu-20
  • a method for producing a high-strength stainless steel seamless pipe for oil wells having a yield strength YS: 654 MPa or more which is subjected to a tempering treatment to be heated to a temperature of 700 ° C. or less.
  • a quenching treatment is performed to cool to 100 ° C. or lower at a cooling rate of air cooling or higher.
  • a high-strength stainless steel seamless pipe for oil wells that has high strength, excellent corrosion resistance, and excellent low-temperature toughness can be easily manufactured, and has a remarkable industrial effect.
  • the ferrite grains can be made fine up to the thickness center of a high-strength stainless steel seamless steel pipe, and the thickness at which the processing amount at the center of the thickness cannot be increased. Even in the seamless steel pipe, there is an effect that the low temperature toughness can be improved.
  • the manufacturing method of the high strength stainless steel seamless steel pipe for oil wells of the present invention is a steel material, a steel pipe material processing step for heating and hot-working to make a steel pipe material, and the steel pipe material is heated, piped, molded,
  • a method for producing a seamless steel pipe comprising a hot working step for making a seamless steel pipe and a heat treatment step for heat-treating the seamless steel pipe, wherein the steel material is in mass%, C: 0.005-0.05%, Si : 0.05-0.5%, Mn: 0.2-1.8%, P: 0.03% or less, S: 0.005% or less, Cr: 15.5-18.0%, Ni: 1.5-5.0%, Mo: 1.0-3.5%, V: 0.02- Contains 0.2%, Al: 0.001 to 0.050%, N: 0.001 to 0.15%, O: 0.006% or less so as to satisfy formula (1) and formula (2) below, with the balance being Fe and inevitable impurities
  • the heating in the steel pipe material processing step and the hot working step is performed at
  • the heat treatment in the heat treatment step is subjected to tempering treatment of heating to a temperature of 700 ° C. or less.
  • the high strength stainless steel seamless steel pipe for oil wells obtained by this production method has a yield strength of YS: 654 MPa or more.
  • Cr + Mo + 0.3Si-43.5C-0.4Mn-Ni-0.3Cu-9N ⁇ 11.5
  • Cr, Ni, Mo, Cu, C, Si, Mn, N Content of each element (mass%)
  • the steel material is heated and hot worked to obtain a steel pipe material.
  • molten steel having a desired composition is melted using a conventional melting furnace such as a converter or an electric furnace, and a slab produced by a conventional casting method such as a continuous casting method is used as a steel material.
  • a conventional melting furnace such as a converter or an electric furnace
  • a slab produced by a conventional casting method such as a continuous casting method
  • the steel materials used in the present invention are in mass%, C: 0.005-0.05%, Si: 0.05-0.5%, Mn: 0.2-1.8%, P: 0.03% or less, S: 0.005% or less, Cr: 15.5- 18.0%, Ni: 1.5 to 5.0%, Mo: 1.0 to 3.5%, V: 0.02 to 0.2%, Al: 0.001 to 0.050%, N: 0.001 to 0.15%, O: 0.006% or less, the following formula (1) And the following formula (2) Cr + 0.65Ni + 0.6Mo + 0.55Cu-20C ⁇ 19.5 ......... (1) Cr + Mo + 0.3Si-43.5C-0.4Mn-Ni-0.3Cu-9N ⁇ 11.5 (2) (Here, Cr, Ni, Mo, Cu, C, Si, Mn, N: content of each element (mass%)) So that the balance is composed of Fe and inevitable impurities.
  • the steel material may contain one group or two or more groups selected from the following groups A to C in addition to the above composition.
  • Group A Cu: 3.5% or less
  • Group B Nb: 0.2% or less
  • Ti 0.3% or less
  • Zr 0.2% or less
  • W 3.0% or less
  • B 0.01% or less selected from 0.01% or less
  • Group C one or two selected from Ca: 0.01% or less
  • REM 0.01% or less
  • C 0.005-0.05%
  • C needs to contain 0.005% or more in order to secure a desired strength.
  • C exceeds 0.05%, sensitization during tempering due to Ni inclusion increases.
  • the C content is limited to a range of 0.005 to 0.05%.
  • the C content is 0.030 to 0.040%.
  • Si 0.05-0.5%
  • Si is an element that acts as a deoxidizer, and in order to obtain such an effect, it is necessary to contain 0.05% or more of Si.
  • the content of Si exceeding 0.5% decreases the corrosion resistance and hot workability. Therefore, the Si content is limited to the range of 0.05 to 0.5%.
  • the Si content is 0.10 to 0.30%.
  • Mn 0.2-1.8% Mn has the effect of increasing strength. In order to obtain such an effect, it is necessary to contain 0.2% or more of Mn. On the other hand, when Mn is contained exceeding 1.8%, toughness is reduced. Therefore, the Mn content is limited to the range of 0.2 to 1.8%. Preferably, the Mn content is 0.20 to 1.00%. More preferably, the Mn content is 0.30 to 0.50%.
  • P 0.03% or less
  • P is an element that segregates at grain boundaries as impurities and adversely affects corrosion resistance, low temperature toughness, etc.
  • a P content of 0.03% or less is acceptable because it does not have a significant adverse effect on corrosion resistance, low temperature toughness, and the like. For this reason, the P content is limited to 0.03% or less.
  • the P content is 0.02% or less.
  • S 0.005% or less S is an element that significantly reduces hot workability, and it is desirable to reduce it as much as possible. However, excessive reduction leads to an increase in refining costs. If the S content is 0.005% or less, normal hot working can be performed. For this reason, S content was limited to 0.005% or less. Preferably, the S content is 0.002% or less.
  • Cr 15.5-18.0% Cr has a function of forming a protective film and improving corrosion resistance. Furthermore, the strength of the steel is increased by solid solution. In order to obtain such an effect, it is necessary to contain 15.5% or more of Cr. On the other hand, when Cr is contained in a large amount exceeding 18.0%, the hot workability is lowered and the strength is also lowered. Therefore, the Cr content is limited to the range of 15.5 to 18.0%. Preferably, the Cr content is 16.6 to 17.5%.
  • Ni 1.5-5.0%
  • Ni has the effect of strengthening the protective film and enhancing the corrosion resistance. Furthermore, it dissolves to increase the strength of the steel and further improve the toughness. Such an effect is recognized when the Ni content is 1.5% or more.
  • the Ni content is 1.5% or more.
  • the Ni content is 2.5 to 4.5%. More preferably, the Ni content is 3.5 to 4.0%.
  • Mo 1.0-3.5%
  • Mo increases corrosion resistance by increasing resistance to pitting corrosion generated by chlorine ions (Cl ⁇ ).
  • the Mo content is limited to the range of 1.0 to 3.5%.
  • the Mo content is 2.0 to 3.5%. More preferably, the Mo content is 2.0 to 3.0%.
  • V 0.02 to 0.2%
  • V has the effect of increasing the strength and improving the corrosion resistance. In order to obtain such an effect, it is necessary to contain 0.02% or more of V. On the other hand, if V exceeds 0.2%, toughness decreases. Therefore, the V content is limited to the range of 0.02 to 0.2%. Preferably, the V content is 0.02 to 0.08%. More preferably, the V content is 0.04 to 0.07%.
  • Al 0.001 to 0.050%
  • Al is an element that acts as a deoxidizer, and in order to obtain such an effect, it is necessary to contain 0.001% or more of Al.
  • the content of Al exceeding 0.050% adversely affects toughness.
  • the Al content is limited to 0.001 to 0.050%. More preferably, the Al content is 0.002 to 0.030%.
  • N 0.001 to 0.15%
  • N is an element that significantly improves the pitting corrosion resistance. In order to obtain such an effect, the N content of 0.001% or more is required. On the other hand, when N exceeds 0.15%, various nitrides are formed and the toughness is lowered. Therefore, the N content is limited to the range of 0.001 to 0.15%. Preferably, the N content is 0.002 to 0.008%.
  • O 0.006% or less
  • O (oxygen) exists as an oxide in steel and adversely affects various properties. For this reason, it is desirable to reduce the O content as much as possible. In particular, when O is contained in a large amount exceeding 0.006%, the hot workability, toughness, and corrosion resistance are remarkably deteriorated. Therefore, the O (oxygen) content is limited to 0.006% or less.
  • the above components are included in the above range, and the following formula (1) and formula (2): Cr + 0.65Ni + 0.6Mo + 0.55Cu-20C ⁇ 19.5 (1) Cr + Mo + 0.3Si-43.5C-0.4Mn-Ni-0.3Cu-9N ⁇ 11.5 (2)
  • the content is adjusted so as to satisfy.
  • Cr, Ni, Mo, Cu, C, Si, Mn, and N are content (mass%) of each element.
  • the elements not included in the elements described in the formulas (1) and (2) are calculated as 0%. To do.
  • CO 2, Cl - significantly the corrosion resistance in high temperature corrosive environments comprising improves.
  • (1) left side value is preferably set to 20.0 or higher.
  • hot workability is improved by adjusting the Cr, Mo, Si, C, Mn, Ni, Cu, and N contents so as to satisfy the formula (2).
  • P, S, and O are remarkably reduced, but only reducing P, S, and O ensures the hot workability necessary and sufficient for forming martensitic stainless steel seamless pipes.
  • Cr, Mo, Si, C, Mn should be satisfied so that P, S, and O are reduced and (2) is satisfied. It is important to adjust the contents of Ni, Cu and N.
  • the right side value of the formula (2) is 12.0 or more.
  • the balance other than the above components is Fe and inevitable impurities.
  • As an inevitable impurity for example, Co: 0.1% or less is acceptable.
  • one or more groups selected from Group A to Group C can be further contained as selective elements.
  • Group A Cu: 3.5% or less
  • Group B Cu strengthens the protective film, suppresses the penetration of hydrogen into the steel, and improves the resistance to sulfide stress corrosion cracking. In order to acquire such an effect, it is desirable to contain Cu 0.5% or more. On the other hand, if Cu content exceeds 3.5%, CuS grain boundary precipitation occurs, and hot workability decreases. For this reason, when Cu is contained, the Cu content is preferably limited to 3.5% or less. The Cu content is more preferably 0.6 to 1.2%, still more preferably 0.8 to 1.14%.
  • Group B Nb: 0.2% or less, Ti: 0.3% or less, Zr: 0.2% or less, W: 3.0% or less, B: 0.01% or less selected from Group B: Nb, Ti , Zr, W, and B are all elements contributing to an increase in strength, and can be selected and contained as necessary.
  • Nb 0.03% or more
  • Ti 0.03% or more
  • Zr 0.03% or more
  • W 0.2% or more
  • B 0.0002% or more
  • Group C Ca: 0.01% or less
  • REM One or two types selected from 0.01% or less Group C: Ca
  • REM has the effect of spheroidizing the shape of sulfide inclusions, and intervenes It is an element that has the effect of reducing the lattice strain of the matrix around the object and reducing the hydrogen trapping ability of inclusions, and can contain one or two kinds as necessary.
  • it contains more than Ca: 0.01% and REM: 0.01% the corrosion resistance decreases. For this reason, when it contains, it is preferable to limit to Ca: 0.01% or less and REM: 0.01% or less.
  • the steel material having the above composition is heated to a predetermined temperature by the heating device 1 shown in FIG. 1 and hot-worked by the hot processing device 2 to obtain a steel pipe material.
  • a round billet of a predetermined shape is used.
  • a hot working apparatus such as a steel slab rolling mill (rough and finish rolling mill) to be used is usually applicable.
  • the obtained steel pipe material is charged into a steel pipe material heating device 3 and heated to a predetermined temperature, and then the heated steel pipe material is hot-worked by a hot working device 4 to produce a product pipe (seam A hot-working process is carried out.
  • reheating may be performed by the reheating device 5 and hot working may be continued.
  • the hot working device 4 used in the hot working process is usually a hot working device used when the steel pipe material is a seamless steel pipe having a predetermined size, such as a Mannesmann-plug mill method, a Mannesmann mandrel mill method. Any hot working apparatus such as can be applied.
  • a Mannesmann inclined piercing machine using a barrel-type roll, a cone-type roll, or the like can be applied.
  • any conventionally known piercing and rolling apparatus such as a hot extrusion piercing machine can be applied.
  • the hot working device 4 there is a rolling device 42 that performs hot working on the hollow material obtained by the piercing and rolling device 41 to form a seamless steel pipe having a predetermined shape.
  • the rolling device 42 any conventionally known rolling device that performs reduction rolling, straightening rolling, or the like can be applied.
  • the rolling device 42 there are an elongator 421 for expanding the hollow element tube, a plug mill 422 for extending the expanded hollow element thinly and long, a reeler 423 for smoothing the inner and outer surfaces of the hollow element tube, and a hollow element tube. It is preferable that the sizing mill 424 that adjusts to a predetermined size is arranged in that order.
  • the reheating apparatus 5 for compensating for the drop in the steel pipe temperature can be installed in the intermediate process of hot rolling.
  • FIG. 1 the example provided in the entrance side of the sizing mill 424 is shown.
  • the rolling device 42 a mandrel mill in which the hollow hollow tube is a hollow steel tube of a predetermined size, a reducer that performs a slight reduction to adjust the outer diameter and thickness. May be sequentially arranged.
  • the heating of the steel material in the steel pipe material processing step described above, and the heating or reheating of the steel pipe material in the hot processing step described above are performed under a temperature condition where the austenite phase is at least 10% by volume fraction.
  • the heating device 1 used for heating the steel material in the steel tube material processing step may be any ordinary heating furnace that can heat the steel material to a predetermined temperature, and is not particularly limited.
  • the walking beam heating furnace Can be illustrated.
  • an induction heating furnace may be used.
  • the steel pipe raw material heating apparatus 3 used for heating the steel pipe raw material in the hot working process described above may be any ordinary heating furnace capable of heating the steel pipe raw material to a predetermined temperature, and is not particularly limited.
  • a rotary hearth type heating furnace can be exemplified. Note that an induction heating furnace may be used.
  • the heating in the steel tube material processing step, the heating in the hot processing step, or the reheating causes the ferrite grains to grow under a temperature condition in which the austenite phase fraction is less than 10% in volume fraction.
  • the structure of the product pipe becomes coarse, and it becomes impossible to secure desired characteristics, particularly desired low temperature toughness.
  • heating (including reheating) in the steel pipe material processing step and the hot processing step was limited to temperature conditions where the austenite phase fraction was 10% or more in terms of volume fraction. If the austenite phase fraction during heating is less than 10% in terms of volume fraction, the ferrite grains grow remarkably, and it becomes impossible to secure desired fine ferrite grains, and the low temperature toughness of the product pipe is lowered.
  • the austenite phase fraction during heating depends on the composition and the heating temperature
  • the austenite phase fraction and the heating temperature are preliminarily determined by an equilibrium calculation or a heating experiment according to the composition of the target steel pipe. Know the relationship in detail.
  • the “heating temperature” is the highest heating temperature of the heating from the viewpoint of the austenite phase fraction during heating.
  • the holding time at the maximum heating temperature is not particularly limited. The influence of the holding time at the maximum heating temperature is small compared to the influence of the heating temperature, and it is desirable to hold it for a short time from the viewpoint of productivity, etc. Needless to say, it is limited.
  • the lower limit temperature at which the austenite phase fraction is less than 10% in terms of volume fraction is obtained from the relationship between the austenite phase fraction during heating and the heating temperature ascertained in advance.
  • the heating described above is carried out by adjusting the temperature to be lower than the temperature. And it is preferable to set it as 1000 degreeC or more from a viewpoint of keeping hot workability favorable. In the case of performing piercing and rolling as hot working, it is more preferable that the temperature range is 1100 ° C. or higher.
  • the steel pipe material heated under the above heating conditions is subjected to a hot working process to be a product pipe (seamless steel pipe).
  • the hot working process is not particularly limited as long as it can be a seamless steel pipe having a predetermined dimension and shape, and a normal hot working apparatus is used so that the predetermined dimension and shape can be secured. Hot working such as piercing rolling, stretching rolling, reduced diameter rolling, straightening rolling and the like can be performed. After these hot workings, the steel can be cooled to room temperature at a cooling rate equal to or higher than that of air cooling to obtain a seamless steel pipe (heat treated raw pipe) having a predetermined size and shape.
  • the martensite phase becomes the main structure, and a desired quenched structure can be obtained.
  • the “cooling rate higher than air cooling” referred to herein means 0.01 ° C./s or higher.
  • the obtained heat-treated raw pipe (seamless steel pipe) is then heat-treated in a heat treatment step.
  • a tempering treatment is performed by heating to a temperature of 700 ° C. or lower.
  • the structure By heating to a tempering temperature of 700 ° C. or lower, preferably 400 ° C. or higher, and tempering, the structure is mainly composed of a tempered martensite phase and has a structure consisting of a fine ferrite phase and a retained austenite phase. And a high-strength stainless steel seamless steel pipe (product pipe) having excellent low-temperature toughness.
  • a quenching process may be performed before the tempering process described above.
  • the quenching treatment is preferably a treatment of reheating to a quenching temperature: 850 ° C. or higher and then cooling to 100 ° C. or lower, preferably 50 ° C. or lower at a cooling rate of air cooling or higher. If the quenching temperature is less than 850 ° C., quenching may be insufficient and desired strength may not be ensured. For this reason, it is preferable to limit the quenching temperature to a temperature of 850 ° C. or higher. Further, if the quenching temperature is too high, the amount of tempered martensite may be reduced and desired quenching characteristics may not be obtained. Therefore, the temperature is preferably 1050 ° C. or lower. Further, the “cooling rate higher than air cooling” referred to herein means 0.01 ° C./s or higher.
  • subject here refers to the phase with the largest area ratio.
  • structure mainly composed of a tempered martensite phase refers to a case where the phase occupies 50% or more by volume ratio.
  • the residual austenite phase is 20% or less by volume.
  • the ferrite phase is 10 to 40% by volume, preferably 20 to 35%. If the ferrite phase is less than 10%, desired corrosion resistance cannot be obtained. On the other hand, if the content exceeds 40%, the strength decreases.
  • a tempered martensite phase as a measurement method of the structure having a fine ferrite phase and a retained austenite phase, first, from a seamless steel pipe, to collect a specimen for structure observation, Polishing so that the cross section perpendicular to the tube axis direction (C cross section) becomes the observation surface and corroding (corrosion of bilera liquid (mixed with picric acid, hydrochloric acid and ethanol in proportions of 2 g, 10 ml and 100 ml, respectively))
  • the tissue is observed and imaged using an optical microscope (magnification: 100 times).
  • image analysis is performed to obtain a tissue fraction.
  • EBSD method Electro BackscatterElectroDiffraction Method
  • the retained austenite phase fraction is measured using an X-ray diffraction method.
  • the fraction of the tempered martensite phase is calculated as the remainder other than these phases.
  • this structure of the present invention can be controlled by setting a specific component composition, performing a tempering process at a specific temperature, performing a quenching process at a specific temperature, and the like.
  • the quenching temperature is heated to a temperature of 850 ° C. or higher. Even in this case, the heating temperature is adjusted so as to satisfy the temperature condition that the austenite phase is 10% or more by volume. There is a need to. By heating while satisfying such heating conditions, grain growth can be suppressed and desired excellent mechanical properties can be stably obtained.
  • the temperature at which the above heat treatment is performed is the temperature of the outer surface of the steel pipe.
  • Steel pipes with such a structure have a high strength of yield strength: 654 MPa or higher and an excellent low temperature toughness where the absorbed energy at a Charpy impact test at the center of the wall thickness is 50 J or higher at -40 ° C. It has a seamless steel pipe.
  • the steel pipe manufactured by the manufacturing method of the present invention can be a thick steel pipe having a wall thickness exceeding 13 mm.
  • Molten steel having the composition shown in Table 1 was melted in a converter and cast into a slab (slab: thickness 260 mm) by a continuous casting method.
  • a test piece (20 mm ⁇ 20 mm ⁇ 10 mm) was sampled from the obtained slab and subjected to a heat treatment experiment.
  • the test piece was heated to various temperatures in an experimental heat treatment furnace (small heat treatment furnace), held for 30 minutes, then immersed in water and rapidly cooled.
  • specimens for tissue observation were collected, polished and corroded (corrosion solution: Viera solution), and the tissues were observed with an optical microscope (magnification: 100 times) and imaged in each of 9 or more fields of view. .
  • tissue photograph was performed, and the area ratio of the martensite phase was computed. The area ratio of the obtained martensite phase was assumed to be equivalent to the volume fraction of the austenite phase at the heating temperature.
  • Table 1 shows that the lower limit temperature T (° C.) at which the austenite phase is less than 10% is different for each steel having a different composition.
  • the obtained slab was charged into a heating device, heated under the conditions shown in Table 2 (billet rolling: maximum heating temperature, extraction temperature), subjected to hot working (billet rolling), and rounded.
  • Billet outer diameter: 260mm ⁇
  • the obtained steel pipe material is charged into a steel pipe material heating device, heated under the conditions shown in Table 2 (piercing and rolling: maximum heating temperature, extraction temperature), and heat in which a piercer, an elongator, a plug mill, and a reeler are sequentially installed. It was hot-worked with a hot-working machine, and further charged into a re-heating machine and hot-worked (rectified rolling) with a sizing mill to produce a seamless steel pipe (outer diameter 244.5 mm ⁇ x wall thickness 13.84 mm). In addition, it air-cooled after hot processing.
  • heating conditions were five patterns, pattern a to pattern e.
  • the obtained seamless steel pipe was subjected to quenching treatment and tempering treatment under the conditions shown in Table 3 as a heat treatment step.
  • the quenching process was not performed and only the tempering process was performed.
  • the hardening process was set as the process immersed in a water tank, after charging a steel pipe in the hardening heating furnace and heating to the hardening heating temperature shown in Table 3.
  • a tempering treatment was performed under the conditions shown in Table 3 after the quenching treatment or without the quenching treatment. After tempering, air cooling was performed.
  • Specimens were collected from the obtained heat-treated seamless steel pipe and subjected to structure observation, tensile test, impact test and corrosion resistance test.
  • the test method was as follows.
  • Microstructure observation A specimen for microstructural observation is collected from the obtained seamless steel pipe, and is polished and corroded so that a cross section (C cross section) perpendicular to the tube axis direction becomes an observation surface. Then, the tissue was observed and imaged using an optical microscope (magnification: 100 times). Using the obtained tissue photograph, image analysis was performed to obtain a tissue fraction. The ferrite grains were measured by an EBSD method using a scanning electron microscope, and the area of the average crystal grains was calculated with different crystal grains in regions where the orientations of adjacent grains differed by 5 ° or more.
  • the retained austenite phase fraction was measured using an X-ray diffraction method.
  • the calculation was performed using the integral intensity of I ⁇ : ⁇ , the integral intensity of I ⁇ : ⁇ , the crystallographic theoretical calculation value of R ⁇ : ⁇ , and the crystallographic theoretical calculation value of R ⁇ : ⁇ .
  • the fraction of the tempered martensite phase was calculated as the remainder other than these phases.
  • Corrosion resistance test A corrosion test piece (size: thickness 3 mm x width 30 mm x length 40 mm) was sampled from the obtained seamless steel pipe and subjected to a corrosion test. In addition, the corrosion resistance test was not implemented about the steel pipe outside this invention range.
  • the corrosion test was conducted by immersing the corrosion test piece in a test solution retained in an autoclave: 20% by mass NaCl aqueous solution (liquid temperature: 230 ° C., 100 atmospheres CO 2 gas atmosphere), and immersion period: 7 days (168 Time).
  • the test piece after the corrosion test was weighed, and the corrosion rate calculated from the weight loss before and after the corrosion test was obtained. The case where the corrosion rate was less than 0.12 mm / y was regarded as acceptable.
  • the microstructure can be refined, the desired corrosion resistance is maintained, and the yield strength is 654 MPa or more, but the absorbed energy at a test temperature of ⁇ 40 ° C. is 50 J or more.
  • the toughness is remarkably improved.
  • the maximum heating temperature in the heating in the steel pipe material processing step and the heating in the hot processing step is equal to or higher than the lower limit temperature at which the austenite phase is less than 10% in volume fraction. The structure cannot be refined and the desired high toughness cannot be ensured.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Manufacturing & Machinery (AREA)
  • Heat Treatment Of Steel (AREA)

Abstract

Cette invention concerne un procédé de fabrication d'un tube sans soudure haute résistance en acier inoxydable pour puits de pétrole, présentant une excellente résistance à la corrosion et une excellente ténacité à basse température. Un matériau d'acier est configuré pour avoir une composition qui contient de 0,005 à 0,05 % de C, de 0,05 à 0,5 % de Si, de 0,2 à 1,8 % de Mn, 0,03 % ou moins de P, 0,005 % ou moins de S, de 15,5 à 18,0 % de Cr, de 1,5 à 5 % de Ni, de 1,0 à 3,5 % de Mo, de 0,02 à 0,2 % de V, de 0,001 à 0,050 % d'Al, de 0,001 à 0,15 % de N et 0,006 % ou moins de O, de telle sorte que ces éléments satisfont des relations spécifiques. Un tube sans soudure en acier est obtenu par chauffage au cours d'une étape de traitement d'un matériau de tube en acier et par chauffage au cours d'une étape de formage à chaud dans des conditions de température telles que les phases d'austénite pendant le chauffage représentent au moins 10 % en termes de fraction volumique. Suite à cela, une trempe est effectuée, au cours de laquelle le tube sans soudure en acier est chauffé à une température inférieure ou égale à 700 °C.
PCT/JP2015/005248 2014-11-18 2015-10-19 Procédé de fabrication de tube sans soudure haute résistance en acier inoxydable pour puits de pétrole Ceased WO2016079922A1 (fr)

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JP2016145372A (ja) * 2015-02-06 2016-08-12 Ｊｆｅスチール株式会社 油井用高強度ステンレス継目無鋼管の製造方法
WO2018131340A1 (fr) * 2017-01-13 2018-07-19 Ｊｆｅスチール株式会社 Tuyau en acier inoxydable sans soudure à résistance élevée et son procédé de fabrication
JPWO2022224640A1 (fr) * 2021-04-21 2022-10-27
WO2024209843A1 (fr) * 2023-04-06 2024-10-10 Ｊｆｅスチール株式会社 Tuyau en acier inoxydable sans soudure et son procédé de production
EP4372117A4 (fr) * 2021-09-29 2025-10-29 Jfe Steel Corp Tube sans soudure en acier inoxydable à haute résistance pour puits de pétrole et son procédé de fabrication

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JP2013249516A (ja) * 2012-05-31 2013-12-12 Jfe Steel Corp 油井管用高強度ステンレス鋼継目無管およびその製造方法

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JPH05345960A (ja) * 1992-04-24 1993-12-27 Nippon Steel Corp 高Ｃｒ鋼の熱間加工性を向上させる加熱法
JP4867088B2 (ja) * 2001-06-21 2012-02-01 住友金属工業株式会社 高Ｃｒ系継目無鋼管の製造方法
JP5109222B2 (ja) * 2003-08-19 2012-12-26 Ｊｆｅスチール株式会社 耐食性に優れた油井用高強度ステンレス継目無鋼管およびその製造方法

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WO2010050519A1 (fr) * 2008-10-30 2010-05-06 住友金属工業株式会社 Tuyau en acier inoxydable à haute limite élastique présentant une résistance élevée à la corrosion fissurante en présence d'hydrogène sulfuré et une résistance à la corrosion en présence de dioxyde de carbone à haute température
JP2013249516A (ja) * 2012-05-31 2013-12-12 Jfe Steel Corp 油井管用高強度ステンレス鋼継目無管およびその製造方法

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Publication number Priority date Publication date Assignee Title
JP2016145372A (ja) * 2015-02-06 2016-08-12 Ｊｆｅスチール株式会社 油井用高強度ステンレス継目無鋼管の製造方法
WO2018131340A1 (fr) * 2017-01-13 2018-07-19 Ｊｆｅスチール株式会社 Tuyau en acier inoxydable sans soudure à résistance élevée et son procédé de fabrication
JP6384636B1 (ja) * 2017-01-13 2018-09-05 Ｊｆｅスチール株式会社 高強度ステンレス継目無鋼管およびその製造方法
US11268161B2 (en) 2017-01-13 2022-03-08 Jfe Steel Corporation High strength seamless stainless steel pipe and method for producing same
JPWO2022224640A1 (fr) * 2021-04-21 2022-10-27
WO2022224640A1 (fr) * 2021-04-21 2022-10-27 Ｊｆｅスチール株式会社 Tuyau en acier inoxydable et son procédé de fabrication
JP7279863B2 (ja) 2021-04-21 2023-05-23 Ｊｆｅスチール株式会社 ステンレス鋼管およびその製造方法
CN117120653A (zh) * 2021-04-21 2023-11-24 杰富意钢铁株式会社 不锈钢管及其制造方法
EP4293133A4 (fr) * 2021-04-21 2025-07-30 Jfe Steel Corp Tuyau en acier inoxydable et son procédé de fabrication
EP4372117A4 (fr) * 2021-09-29 2025-10-29 Jfe Steel Corp Tube sans soudure en acier inoxydable à haute résistance pour puits de pétrole et son procédé de fabrication
WO2024209843A1 (fr) * 2023-04-06 2024-10-10 Ｊｆｅスチール株式会社 Tuyau en acier inoxydable sans soudure et son procédé de production
JPWO2024209843A1 (fr) * 2023-04-06 2024-10-10

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