WO2024125407A1 - Highly corrosion-resistant oil well steel pipe and preparation method therefor - Google Patents

Highly corrosion-resistant oil well steel pipe and preparation method therefor Download PDF

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Publication number
WO2024125407A1
WO2024125407A1 PCT/CN2023/137477 CN2023137477W WO2024125407A1 WO 2024125407 A1 WO2024125407 A1 WO 2024125407A1 CN 2023137477 W CN2023137477 W CN 2023137477W WO 2024125407 A1 WO2024125407 A1 WO 2024125407A1
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WIPO (PCT)
Prior art keywords
oil well
well pipe
resistant oil
pipe steel
steel
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PCT/CN2023/137477
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French (fr)
Chinese (zh)
Inventor
宋志刚
丰涵
何建国
吴晓涵
朱玉亮
郑文杰
王宝顺
钱炯
王曼
孙文强
潘平伟
苏诚
陈根保
丁斌华
吴明华
姚亮
代卫星
Original Assignee
钢铁研究总院有限公司
浙江久立特材科技股份有限公司
湖州永兴特种不锈钢有限公司
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Publication of WO2024125407A1 publication Critical patent/WO2024125407A1/en

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Classifications

    • 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
    • C22C38/44—Ferrous alloys, e.g. steel alloys containing chromium with nickel with molybdenum or tungsten
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21B—ROLLING OF METAL
    • B21B39/00—Arrangements for moving, supporting, or positioning work, or controlling its movement, combined with or arranged in, or specially adapted for use in connection with, metal-rolling mills
    • 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
    • C21D8/105—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of tubular bodies of ferrous alloys
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C33/00—Making ferrous alloys
    • C22C33/04—Making ferrous alloys by melting
    • 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
    • C22C38/001—Ferrous alloys, e.g. steel alloys containing N
    • 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
    • C22C38/02—Ferrous alloys, e.g. steel alloys containing silicon
    • 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
    • C22C38/04—Ferrous alloys, e.g. steel alloys containing manganese
    • 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
    • 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
    • C21D2211/00—Microstructure comprising significant phases
    • C21D2211/001—Austenite
    • 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
    • C21D2211/00—Microstructure comprising significant phases
    • C21D2211/005—Ferrite
    • 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
    • C21D2211/00—Microstructure comprising significant phases
    • C21D2211/008—Martensite
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P10/00—Technologies related to metal processing
    • Y02P10/20—Recycling

Definitions

  • the present application relates to the technical field of corrosion-resistant steel, and in particular to a highly corrosion-resistant oil well pipe steel and a preparation method thereof.
  • Oil well pipe is an important consumable in the process of oil and gas exploration and development, accounting for about 40% of the total steel used in the oil and gas industry, and is an important part of oil and gas extraction equipment.
  • oil well pipe accounts for an average of 20% to 30% of the entire well construction cost. Therefore, whether the entire petroleum project can proceed smoothly is inseparable from the quality of oil well pipe.
  • the oil well pipe is placed in the casing and is used to collect oil and gas. Due to the flow of corrosive liquids in the oil well pipe, various corrosion-resistant products must be selected according to the corrosion situation.
  • Sichuan gas fields contain H2S
  • some oil and gas wells in Sichuan, North China and western oil and gas fields contain CO2 and H2S , CO2 , and C1 - coexist.
  • higher requirements are also placed on the corrosion resistance of oil well pipes.
  • the material for oil well pipes that resist CO2 corrosion is mainly 13Cr martensitic stainless steel, but martensitic steel cannot be used in an environment containing H2S .
  • 22Cr or 25Cr, 27Cr, the higher the Cr content, the better the corrosion resistance
  • duplex stainless steel with higher alloy content can meet the use requirements of oil well pipes, the material cost is high and is not suitable for large-scale industrial applications in oil and gas production scenarios. In view of the actual situation of oil and gas production in China and the limitation of mineral resources, it is imperative to develop highly corrosion-resistant oil well pipe materials.
  • the present application aims to provide a highly corrosion-resistant oil well pipe steel and a preparation method thereof, so as to solve the problems of high alloy element content and high cost of existing oil well pipe steel.
  • the present application provides a high corrosion resistant oil well pipe steel, wherein the components of the high corrosion resistant oil well pipe steel include, by mass percentage: C: ⁇ 0.03%, Cr: 17.3% to 18.4%, Mo: 0.5% to 2.0%, Ni: 1.0% to 2.8%, Mn: 1.0% to 3.5%, Si: 0.1% to 0.5%, N: 0.1% to 0.25%, P: ⁇ 0.03%, S: ⁇ 0.01%, and the balance is Fe and unavoidable impurities.
  • the composition of the high corrosion resistant oil well pipe steel can be, by mass percentage, C: 0.01% to 0.03%, Cr: 17.4% to 18.4%, Mo: 1.0% to 2.0%, Ni: 1.0% to 2.7%, Mn: 1.4% to 3.2%, Si: 0.1% to 0.5%, N: 0.13% to 0.25%, P: ⁇ 0.03%, S: ⁇ 0.01%, and the balance is Fe and unavoidable impurities.
  • the microstructure of the high corrosion resistant oil well pipe steel is a mixed structure of ferrite + austenite + martensite.
  • the volume percentage of austenite is 20% to 40%, and the volume percentage of martensite is 10% to 40%.
  • the austenite grain size is less than 3 ⁇ m.
  • the present application also provides a method for preparing high corrosion resistant oil well pipe steel, which is used to prepare the above-mentioned high corrosion resistant oil well pipe steel, comprising:
  • Step 1 Melting metal raw materials into molten steel
  • Step 2 smelting the molten steel into continuous casting billets or ingots by continuous casting or mold casting;
  • Step 3 Forging the continuous casting billet or ingot into a forging billet
  • Step 4 Roll the forged billet into a tube billet, and obtain high corrosion-resistant oil well pipe steel by controlling hot rolling and cooling process parameters.
  • step 3 the forging temperature is 1150-1250°C.
  • controlling the hot rolling and cooling process parameters includes: controlling the starting rolling temperature to be above 1050°C, the final rolling temperature to be above 950°C, the deformation in the first rolling pass to be no more than 30%, and the deformation in the final rolling pass to be no more than 50%.
  • the present invention has the following beneficial effects:
  • the high corrosion resistant oil well pipe steel of the present application accurately controls the mass percentage of Cr, Ni, Mn, Mo, and N elements in the steel, and combined with the hot deformation process of controlled rolling and controlled cooling, can obtain a mixed structure of ferrite + austenite + martensite, which greatly improves the corrosion resistance and strength of the oil well pipe steel. Since the 17Cr material of the present application has ultrafine martensite, the tensile strength of the material is better than that of duplex stainless steel with a higher Cr content, and high strength is achieved with a lower Cr content. Compared with the martensitic stainless steel of the prior art, the stainless steel of the present application introduces ferrite and austenite to obtain better intergranular corrosion resistance and H2S stress corrosion resistance.
  • the austenite content in the stainless steel of the present application is much higher than that of martensitic stainless steel. It is difficult to obtain an austenite content greater than 20% in martensitic stainless steel, so the material of the present application has better resistance to hydrogen embrittlement.
  • the steel of the present application not only ensures high strength, good plasticity and toughness, and excellent corrosion resistance, but also can ensure that the yield strength of the steel of the present application is greater than 600MPa (for example, 601-648MPa), the tensile strength is greater than 910MPa (for example, 911-1010MPa), and the elongation is greater than 22% (for example, 23%-24%).
  • 600MPa for example, 601-648MPa
  • the tensile strength is greater than 910MPa (for example, 911-1010MPa)
  • the elongation is greater than 22% (for example, 23%-24%).
  • 180°C CO 2 corrosion rate: 0.028g/m 2 h or less (e.g. 0.0203-0.0275g/m 2 h);
  • the steel of the present application has good toughness and excellent corrosion resistance, and has both the high strength of super martensitic stainless steel oil well pipe materials and the stress corrosion resistance, intergranular corrosion resistance and small amount of H 2 S stress corrosion resistance of duplex stainless steel. Since the Cr and Ni content of the steel of the present application is low, the raw material cost is equivalent to or even slightly lower than that of the super 13Cr martensitic stainless steel in the prior art, and the hot working performance is good, so the steel of the present application has low comprehensive cost, is economical and practical.
  • FIG1 is a microstructure diagram of the steel after hot rolling of Example 1 of the present application.
  • FIG2 is a transmission electron microscope image of point M in FIG1 of the present application.
  • FIG3 is a microstructure diagram of the steel of Example 2 of the present application.
  • FIG4 is a microstructure diagram of the steel of Example 3 of the present application.
  • FIG5 is a microstructure diagram of the steel of Example 4 of the present application.
  • FIG6 is a photograph of the hot-rolled plate of Example 1 of the present application.
  • the present application provides a high corrosion resistant oil well pipe steel, wherein the components of the high corrosion resistant oil well pipe steel include, by mass percentage, C: ⁇ 0.03%, Cr: 17.3% to 18.4%, Mo: 0.5% to 2.0%, Ni: 1.0% to 2.8%, Mn: 1.0% to 3.5%, Si: 0.1% to 0.5%, N: 0.1% to 0.25%, P: ⁇ 0.03%, S: ⁇ 0.01%, and the balance is Fe and unavoidable impurities.
  • Cr+3.3Mo+16N i.e., PREN
  • 60Ni+17Mn-12Mo-800N ⁇ 0
  • Cr, Mo, N, Ni, and Mn refer to the mass percentage of these elements ⁇ 100.
  • the mass percentage of the Cr element is 18.4%
  • the Cr here is 18.4.
  • Cr The main element to ensure the corrosion resistance of stainless steel. It is also a ferrite-forming element. Improper control of Cr content will increase the ferrite content in the organization and reduce the strength. Considering comprehensive considerations, its content is controlled at 17.3% to 18.4%.
  • Ni It is an element that strongly forms and stabilizes austenite and expands the austenite phase region. Ni is an element that improves the toughness and corrosion resistance of stainless steel in reducing media. Ni is also an important element for improving the resistance of austenite phase to transgranular stress corrosion in various media. At the same time, compared with Mn element, Ni element can reduce the cold work hardening tendency of austenite phase. Considering cost control, this application controls its content within 1.0% to 2.8%.
  • Mn It can increase the solubility of N in steel and inhibit the precipitation of harmful phase chromium nitride, but Mn reduces the toughness of stainless steel. Compared with Ni, Mn is an austenite-forming element. Mn has different hardening effects on the austenite phase of stainless steel and the overall material. Therefore, this application controls its content within 1.0% to 3.5%.
  • Si is added as a deoxidizer during the smelting process to achieve a deoxidation effect. Too much addition will deteriorate the intergranular corrosion resistance of the material.
  • the content of Si is controlled within 0.1% to 0.5% in this application.
  • N Like Ni, it is an element that strongly forms and stabilizes austenite and expands the austenite phase. N can also significantly improve the pitting corrosion resistance of the austenite phase in stainless steel, thereby improving the overall pitting corrosion resistance of stainless steel. In some media, N has a good effect on the stress resistance of stainless steel, and there is an optimal value. Further increasing the N content will reduce its stress corrosion resistance. N is also a relatively economical alloying element, but N reduces the hot working performance of stainless steel. Therefore, this application controls its content to 0.1% to 0.25%.
  • the present application comprehensively considers three aspects: guarantee of corrosion resistance, raw material cost caused by alloy element matching, precipitation of harmful phases caused by alloy element matching, and cost change caused by hot working yield.
  • Cr, Ni, Mn, and N in steel in order to ensure corrosion resistance, Cr+3.3Mo+16N ⁇ 26 is controlled.
  • Cr+3.3Mo+16N ⁇ 26 is controlled in order to make the maximum precipitation temperature of harmful phases lower than 750°C and ensure that the material has good hot working properties.
  • it is necessary to control the content of Ni, Mn, Mo, and N elements to meet the following requirements: 60Ni+17Mn-12Mo-800N ⁇ 0.
  • the composition of the above-mentioned high corrosion resistant oil well pipe steel can be calculated by mass percentage: C: 0.01% to 0.03%, Cr: 17.4% to 18.4%, Mo: 1.0% to 2.0%, Ni: 1.0% to 2.7%, Mn: 1.4% to 3.2%, Si: 0.1% to 0.5%, N: 0.13% to 0.25%, P: ⁇ 0.03%, S: ⁇ 0.01%, and the balance is Fe and unavoidable impurities.
  • Cr+3.3Mo+16N i.e., PREN
  • PREN is 26.1 to 27.8, and 60Ni+17Mn-12Mo-800N ⁇ -0.42.
  • the microstructure of the above-mentioned high corrosion-resistant oil well pipe steel is a mixed structure of ferrite + austenite + martensite, wherein the volume percentage of austenite is 20% to 40% (for example, 20% to 35%), and the volume percentage of martensite is 10% to 40% (for example, 30% to 40%).
  • the martensite is dispersed in the austenite in the form of ultrafine sheets, and is alternately stacked with the austenite and divided from each other, so that the austenite has a smaller grain size (for example, the austenite grain size is ⁇ 3 ⁇ m), and the thickness of the martensite sheet is less than 100nm.
  • the high corrosion-resistant oil well pipe steel of the present application is a three-phase structure.
  • the steel of the present application has the characteristics of low Cr and low alloy element content to obtain higher strength. It can also have the characteristics of high strength, resistance to intergranular corrosion, stress corrosion, high toughness and good welding performance, and has excellent comprehensive performance.
  • the composite structure of martensite and austenite can increase the interface density in the organization, thereby obtaining high-strength mechanical properties that are superior to traditional duplex stainless steel.
  • Its balanced phase ratio in the conventional hot working temperature range (900-1180°C) brings excellent hot working performance.
  • the multi-phase composite organizational form after hot working has better corrosion resistance than single-phase martensitic stainless steel while ensuring certain cold working performance.
  • the present application also provides a method for preparing the above-mentioned highly corrosion-resistant oil well pipe steel, comprising:
  • Step 1 Melting metal raw materials into molten steel
  • Step 2 smelting the molten steel into continuous casting billets or ingots by continuous casting or mold casting;
  • Step 3 heating the continuous casting billet or ingot at 1150-1250° C., forging and opening the billet to form a forging billet;
  • Step 4 Heat the forged billet at 1050-1250°C, roll it into a tube billet, and obtain high corrosion resistant oil well pipe steel by controlling the hot rolling and cooling process parameters.
  • the three-phase structure content of the high corrosion resistant oil well pipe steel is: martensite content 10%-40%, austenite content 20%-40%, and the rest is ferrite.
  • the forging temperature is 1150-1250°C. This is because the material of the present application is a two-phase ferrite + austenite when it is higher than 800°C.
  • the ratio of the two phases changes with the heating temperature. The higher the heating temperature, the more ferrite content, and the corresponding austenite content decreases. Selecting this temperature range for heating ensures the full dissolution of harmful precipitated phases, and also makes the ferrite phase content in the material greater than 70%, so that the steel is forged in a single-phase region with better thermoplasticity, avoiding the difference in the thermal deformation capacity of the two phases of ferrite and austenite, which leads to the uncoordinated deformation of the two phases in the forging process and causes forging cracking.
  • the tube is hot-rolled and then water-cooled to room temperature to avoid the precipitation of harmful phases.
  • controlling the hot rolling and cooling process parameters includes: controlling the starting rolling temperature to be above 1050° C. (e.g., 1050-1200° C.), the final rolling temperature to be above 950° C. (e.g., 950° C.-1050° C.), the deformation amount of the first rolling pass to be no more than 30%, and the deformation amount of the final rolling pass to be no more than 50%.
  • the high corrosion resistant oil well pipe steel of the present application accurately controls the mass percentage of Cr, Ni, Mn, Mo, and N elements in the steel, and combines the hot deformation process of controlled rolling and controlled cooling to obtain a mixed structure of ferrite + austenite + martensite, which greatly improves the corrosion resistance and toughness of the oil well pipe steel.
  • increasing the Cr content can increase the strength of the material, but because the 17Cr material of the present application has ultrafine martensite, the tensile strength of the material is better than that of the material with a higher Cr content.
  • Duplex stainless steel In stainless steel, increasing the Cr content can increase the strength of the material, but because the 17Cr material of the present application has ultrafine martensite, the tensile strength of the material is better than that of the material with a higher Cr content.
  • the 17Cr three-phase stainless steel in the present application controls the content combination of Cr, Ni, Mn, Mo, and N, and obtains a three-phase structure with adjustable martensite content after hot rolling, thereby achieving high strength with a lower Cr content.
  • ferrite and austenite are introduced into the stainless steel in the present application to obtain better intergranular corrosion resistance and H2S stress corrosion resistance.
  • the austenite content in the stainless steel in the present application is much higher than that in martensitic stainless steel. It is difficult to obtain an austenite content greater than 20% in martensitic stainless steel. Therefore, the material in the present application has better resistance to hydrogen embrittlement.
  • the steel of the present application not only ensures high strength, good plasticity and toughness, and excellent corrosion resistance, but can also ensure that the yield strength of the steel of the present application is greater than 600MPa (for example, 601-648MPa), the tensile strength is greater than 910MPa (for example, 911-1010MPa), and the elongation is greater than 22% (for example, 23%-24%).
  • 600MPa for example, 601-648MPa
  • the tensile strength is greater than 910MPa (for example, 911-1010MPa)
  • the elongation is greater than 22% (for example, 23%-24%).
  • 180°C CO 2 corrosion rate: 0.028g/m 2 h or less (e.g. 0.0203-0.0275g/m 2 h);
  • the steel of the present application has good toughness and excellent corrosion resistance, and has both the high strength of super martensitic stainless steel oil well pipe materials and the stress corrosion resistance, intergranular corrosion resistance and small amount of H 2 S stress corrosion resistance of duplex stainless steel. Since the Cr and Ni content of the steel of the present application is low, the raw material cost is equivalent to or even slightly lower than that of the super 13Cr martensitic stainless steel of the prior art, and the hot working performance is good, so the steel of the present application has low comprehensive cost, is economical and practical.
  • Examples 1-4 of the present application provide a highly corrosion-resistant oil well pipe steel and a preparation method thereof.
  • the chemical compositions of the steels of Examples 1-4 are shown in Table 1.
  • the preparation method of Example 1 comprises:
  • Step 1 Melt the metal raw materials into molten steel; Use the die casting method to smelt the molten steel into Ingot, to obtain casting billet;
  • Step 2 After heating the ingot to 1150°C and keeping the temperature for 2 hours, forging and opening the ingot to form a forging ingot;
  • Step 3 Keep the forging billet at 1050°C for 2h and roll it into a tube billet.
  • the hot rolling and cooling process parameters the deformation amount of the first pass is 25%, the deformation amount of the final rolling pass is 48%, the final rolling plate thickness is controlled at about 3.5mm, and water cooling
  • the final rolling temperature is controlled at 960°C to adjust the three-phase structure content
  • the ferrite content is 40%
  • the martensite content is 40%
  • austenite content 20%.
  • the preparation method of Example 2 comprises:
  • Step 1 Melting metal raw materials into molten steel; using a die casting method to smelt the molten steel into steel ingots to obtain ingots;
  • Step 2 After heating the ingot to 1180°C and keeping the temperature for 1.5 hours, forging and opening the ingot to form a forging ingot;
  • Step 3 Keep the forging billet at 1150°C for 2h and roll it into a tube billet.
  • the hot rolling and cooling process parameters the deformation amount of the first pass is 28%, the deformation amount of the final rolling pass is 45%, the final rolling plate thickness is controlled at about 3.5mm, and water cooling
  • the final rolling temperature at 1000°C, the three-phase structure content is adjusted to 45% ferrite, 30% martensite, and 25% austenite.
  • the preparation method of Example 3 comprises:
  • Step 1 Melting metal raw materials into molten steel; using a die casting method to smelt the molten steel into steel ingots to obtain ingots;
  • Step 2 After heating the ingot to 1200°C and keeping the temperature for 1 hour, forging and opening the ingot to make a forging ingot;
  • Step 3 The forged billet is kept at 1200°C for 2h and rolled into a tube billet.
  • the hot rolling and cooling process parameters the deformation of the first pass is 23%, the deformation of the final rolling pass is 46%, the final rolling thickness is controlled at about 3.5mm, and water cooling
  • the final rolling temperature is controlled at 1050°C (the three-phase structure content is adjusted to 40% ferrite, 30% martensite, and 30% austenite.
  • the preparation method of Example 4 comprises:
  • Step 1 Melt the metal raw materials into molten steel; Use the die casting method to smelt the molten steel into Casting ingots to obtain billets;
  • Step 2 After heating the ingot to 1250°C and keeping it for 1 hour, forging and blanking are performed to form a forging billet;
  • Step 3 Keep the forging billet at 1200°C for 2h and roll it into a tube billet.
  • the hot rolling and cooling process parameters the deformation amount of the first pass is 26%, the deformation amount of the final rolling pass is 45%, the final rolled plate thickness is controlled at about 3.5mm, and water cooling
  • the final rolling temperature at 1050°C, the three-phase structure content is adjusted to 35% ferrite, 30% martensite, and 35% austenite.
  • Example 1 The specific process parameters of Examples 1-4 are shown in Table 2, the mechanical properties of Examples 1-4 are shown in Table 3, FIG1 is a microstructure diagram of the steel of Example 1 of the present application, and FIG2 is a transmission electron microscope image of point M in FIG1 of the present application, wherein the upper left corner is the diffraction spot of the martensite and austenite matrix at point A, which can prove the crystal structure of the black martensite sheet and the thickness of the martensite sheet is less than 100 nm.
  • Figures 3 to 5 are respectively microstructure diagrams of the steel of Examples 2 to 4 of the present application; the microstructures of Examples 1 to 4 are shown in Table 4 below.
  • the microstructure of the high corrosion resistant oil well pipe steel of the present application is a mixed structure of ferrite + austenite + martensite, wherein the volume percentage of austenite is 20% to 40% (e.g., 20% to 35%), and the volume percentage of martensite is 10% to 40% (e.g., 30% to 40%), and the martensite is dispersed in the austenite in the form of ultrafine flakes, alternately stacked with austenite, and divided from each other, so that the austenite has a smaller grain size (e.g., austenite grain size ⁇ 3 ⁇ m), and the thickness of the martensite sheet is less than 100 nm.
  • the volume percentage of austenite is 20% to 40% (e.g., 20% to 35%)
  • the volume percentage of martensite is 10% to 40% (e.g., 30% to 40%)
  • CO2 partial pressure 4.48MPa
  • total test pressure 10MPa
  • Test temperature 180°C or 200°C;
  • Test time 720 hours.
  • the corrosion conditions for pitting corrosion rate are as follows:
  • Test temperature 22 ⁇ 2°C;
  • Test time 72 hours;
  • Sample size 50 ⁇ 25 ⁇ 3mm, polished to 2000# sandpaper.
  • the test temperature is 22 ⁇ 2°C;
  • Test time 72 hours;
  • Sample size 50 ⁇ 25 ⁇ 3mm, polished to 2000# sandpaper.
  • the test temperature is 22 ⁇ 2°C;
  • Test time 720 hours
  • Sample size 50 ⁇ 5 ⁇ 2mm, polished to 2000# sandpaper;
  • the (180°C) CO 2 corrosion rate of the high corrosion resistant oil well pipe steel of Examples 1-4 is less than 0.028 g/m 2 h (e.g., 0.0203-0.0275 g/m 2 h); the (200°C) CO 2 corrosion rate is less than 0.1 g/m 2 h (e.g., 0.078-0.099 g/m 2 h); the pitting corrosion rate is less than 2.5 g/m 2 h (e.g., 1.693-2.433 g/m 2 h); the crevice corrosion rate is less than 5.9 g/m 2 h (e.g., 3.303-5.852 g/m 2 h); and the H 2 S stress corrosion test is passed.
  • 0.028 g/m 2 h e.g., 0.0203-0.0275 g/m 2 h
  • the (200°C) CO 2 corrosion rate is less than 0.1 g/m 2 h (e.g., 0.078-0.099 g/m
  • FIG. 5 is a diagram showing the results of the H 2 S stress corrosion test of Example 1.
  • FIG6 shows a photo of the hot rolled plate of Example 1, showing that there is no cracking at the edge, and the yield rate of the steel of the examples of the present application in the actual production process reaches more than 90%.
  • This comparative example provides a corrosion-resistant oil well pipe steel and a preparation method thereof.
  • the corrosion-resistant oil well pipe steel of this comparative example is 13Cr and is prepared by the current mature process of 13Cr.
  • the composition of the corrosion-resistant oil well pipe steel of this comparative example is C: 0.03%, Cr: 13%, Ni: 5%, Mo: 2%, Mn: 0.5%, Si: 0.5%, and the preparation method is: after heating and forging at 1150°C, water cooling, and then reheating to 860°C for 2h, quenching, and tempering at 620°C for 1 hour.
  • the microstructure of the steel of this comparative example is martensite (93%) + austenite (7%).
  • the mechanical properties are shown in Table 3 above, and the corrosion resistance results are shown in Table 5 above.
  • This comparative example provides a corrosion-resistant oil well pipe steel and a preparation method thereof.
  • the corrosion-resistant oil well pipe steel of this comparative example has the following components: C: 0.03%, Cr: 16%, Mo: 1.21%, N: 0.22%, Mn: 2.11%, and Si: 0.5%.
  • the preparation method is the same as that of Example 1.
  • microstructure of the steel of this comparative example is ferrite (15%) + martensite (65%) + austenite (20%).
  • the mechanical properties are shown in Table 3, and the corrosion resistance results are shown in Table 5.
  • This comparative example provides a corrosion-resistant oil well pipe steel and a preparation method thereof.
  • the corrosion-resistant oil well pipe steel of this comparative example has the following components: C: 0.04%, Cr: 16.5%, Ni: 1.12%, Mo: 1.32%, N: 0.16%, Mn: 2.82%, and Si: 0.5%.
  • the preparation method is the same as that of Example 1.
  • microstructure of the steel of this comparative example is ferrite (20%) + martensite (60%) + austenite (20%).
  • the mechanical properties are shown in Table 3, and the corrosion resistance results are shown in Table 5.
  • the high corrosion-resistant oil well pipe steel of the present application accurately controls the mass percentages of Cr, Ni, Mn, Mo, and N elements in the steel, and combines the hot deformation process of controlled rolling and controlled cooling to obtain a mixed structure of ferrite + austenite + martensite, which greatly improves the corrosion resistance and toughness of the oil well pipe steel.
  • the raw material cost is equivalent to or even slightly lower than that of the super 13Cr martensitic stainless steel in the prior art, and the hot processing performance is good.
  • the corrosion resistance of the high corrosion-resistant oil well pipe steel of the present application is better than that of the super 13Cr martensitic stainless steel. Therefore, the steel of the present application has low comprehensive cost, is economical, and is practical.

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Abstract

A highly corrosion-resistant oil well steel pipe and a preparation method therefor, relating to the technical field of corrosion-resistant steel, and used for solving the problems in the prior art of high alloy element content and high costs of an oil well steel pipe. The highly corrosion-resistant oil well steel pipe comprises the following components in percentage by mass: C: ≤0.03%; Cr: 17.3%-18.4%; Mo: 0.5%-2.0%; Ni: 1.0%-2.8%; Mn: 1.0%-3.5%; Si: 0.1%-0.5%; N: 0.1%-0.25%; P: ≤0.03%; S: ≤0.01%; and the remainder being Fe and inevitable impurities. The oil well steel pipe has high strength, good plasticity and toughness, and excellent corrosion resistance.

Description

一种高耐蚀油井管钢及其制备方法A high corrosion resistant oil well pipe steel and preparation method thereof 技术领域Technical Field
本申请涉及耐蚀钢技术领域，特别涉及一种高耐蚀油井管钢及其制备方法。The present application relates to the technical field of corrosion-resistant steel, and in particular to a highly corrosion-resistant oil well pipe steel and a preparation method thereof.
背景技术Background technique
油井管是石油、天然气勘探开发过程中的重要耗材，占油气工业用钢总量的40％左右，是石油、天然气开采设备中的重要组成部分。作为一种重要的石油装备物资，油井管在整个建井成本中平均占20％～30％。因此，整个石油工程能否顺利进行，与油井管材质量密不可分。油井管置于套管之中，用于采集油气。由于油井管内腐蚀性液体的流动，故须根据腐蚀情况选用各种抗腐蚀产品。在中国，四川气田含H2S,四川、华北和西部油气田的一些油气井含CO2及H2S、CO2、C1-共存。在这种采油条件下，对油井管的耐腐蚀性能也提出了更高要求。目前抗CO2腐蚀的油井管用材料以13Cr马氏体不锈钢为主，但马氏体钢不能在含H2S的环境使用。尽管选用更高合金含量的22Cr(或25Cr、27Cr，Cr含量越高耐蚀性越好)型双相不锈钢可以满足油井管使用要求，但是材料成本高，不适合油气开采场景的大批量工业应用。针对中国油气开采实际情况和矿产资源限制，开发高耐蚀油井管材料势在必行。Oil well pipe is an important consumable in the process of oil and gas exploration and development, accounting for about 40% of the total steel used in the oil and gas industry, and is an important part of oil and gas extraction equipment. As an important petroleum equipment material, oil well pipe accounts for an average of 20% to 30% of the entire well construction cost. Therefore, whether the entire petroleum project can proceed smoothly is inseparable from the quality of oil well pipe. The oil well pipe is placed in the casing and is used to collect oil and gas. Due to the flow of corrosive liquids in the oil well pipe, various corrosion-resistant products must be selected according to the corrosion situation. In China, Sichuan gas fields contain H2S , and some oil and gas wells in Sichuan, North China and western oil and gas fields contain CO2 and H2S , CO2 , and C1 - coexist. Under such oil production conditions, higher requirements are also placed on the corrosion resistance of oil well pipes. At present, the material for oil well pipes that resist CO2 corrosion is mainly 13Cr martensitic stainless steel, but martensitic steel cannot be used in an environment containing H2S . Although the use of 22Cr (or 25Cr, 27Cr, the higher the Cr content, the better the corrosion resistance) duplex stainless steel with higher alloy content can meet the use requirements of oil well pipes, the material cost is high and is not suitable for large-scale industrial applications in oil and gas production scenarios. In view of the actual situation of oil and gas production in China and the limitation of mineral resources, it is imperative to develop highly corrosion-resistant oil well pipe materials.
目前国内外关于良好综合性能油井管钢的品种和相应工艺流程已经有很多的专利，但大多存在成本过高或工艺复杂等问题而无法满足大量生产和实际应用的需要。At present, there are many patents at home and abroad on the varieties and corresponding process flows of oil well pipe steel with good comprehensive performance, but most of them have problems such as high cost or complex process and cannot meet the needs of mass production and practical application.
发明内容Summary of the invention
鉴于上述情况，本申请旨在提供一种高耐蚀油井管钢及其制备方法，用于解决现有油井管钢合金元素含量较高、成本较高的问题。In view of the above situation, the present application aims to provide a highly corrosion-resistant oil well pipe steel and a preparation method thereof, so as to solve the problems of high alloy element content and high cost of existing oil well pipe steel.
本申请的目的主要是通过以下技术方案实现的： The purpose of this application is mainly achieved through the following technical solutions:
一方面，本申请提供了一种高耐蚀油井管钢，高耐蚀油井管钢的组分以质量百分比计包括：C：≤0.03％、Cr：17.3％～18.4％、Mo：0.5％～2.0％、Ni：1.0％～2.8％、Mn：1.0％～3.5％、Si：0.1％～0.5％、N：0.1％～0.25％、P：≤0.03％、S：≤0.01％，余量为Fe及不可避免的杂质。On the one hand, the present application provides a high corrosion resistant oil well pipe steel, wherein the components of the high corrosion resistant oil well pipe steel include, by mass percentage: C: ≤0.03%, Cr: 17.3% to 18.4%, Mo: 0.5% to 2.0%, Ni: 1.0% to 2.8%, Mn: 1.0% to 3.5%, Si: 0.1% to 0.5%, N: 0.1% to 0.25%, P: ≤0.03%, S: ≤0.01%, and the balance is Fe and unavoidable impurities.
在一种可能的设计中，高耐蚀油井管钢的组分中，Cr+3.3Mo+16N≥26。In a possible design, in the composition of the high corrosion resistant oil well pipe steel, Cr+3.3Mo+16N≥26.
在一种可能的设计中，高耐蚀油井管钢的组分中，60Ni+17Mn-12Mo-800N≤0。In a possible design, in the composition of the high corrosion resistant oil well pipe steel, 60Ni+17Mn-12Mo-800N≤0.
在一种可能的设计中，高耐蚀油井管钢的组分以质量百分比计可以为：C：0.01％～0.03％、Cr：17.4％～18.4％、Mo：1.0％～2.0％、Ni：1.0％～2.7％、Mn：1.4％～3.2％、Si：0.1％～0.5％、N：0.13％～0.25％、P：≤0.03％、S：≤0.01％，余量为Fe及不可避免的杂质。In a possible design, the composition of the high corrosion resistant oil well pipe steel can be, by mass percentage, C: 0.01% to 0.03%, Cr: 17.4% to 18.4%, Mo: 1.0% to 2.0%, Ni: 1.0% to 2.7%, Mn: 1.4% to 3.2%, Si: 0.1% to 0.5%, N: 0.13% to 0.25%, P: ≤0.03%, S: ≤0.01%, and the balance is Fe and unavoidable impurities.
在一种可能的设计中，高耐蚀油井管钢的微观组织为铁素体+奥氏体+马氏体的混合组织。In a possible design, the microstructure of the high corrosion resistant oil well pipe steel is a mixed structure of ferrite + austenite + martensite.
在一种可能的设计中，高耐蚀油井管钢的微观组织中，奥氏体的体积百分含量为20％～40％，马氏体的体积百分含量为10％～40％。In a possible design, in the microstructure of the high corrosion resistant oil well pipe steel, the volume percentage of austenite is 20% to 40%, and the volume percentage of martensite is 10% to 40%.
在一种可能的设计中，高耐蚀油井管钢的微观组织中，奥氏体晶粒尺寸＜3μm。In a possible design, in the microstructure of the high corrosion resistant oil well pipe steel, the austenite grain size is less than 3 μm.
另一方面，本申请还提供了一种高耐蚀油井管钢的制备方法，用于制备上述高耐蚀油井管钢，包括：On the other hand, the present application also provides a method for preparing high corrosion resistant oil well pipe steel, which is used to prepare the above-mentioned high corrosion resistant oil well pipe steel, comprising:
步骤1：将金属原材料熔炼成钢水；Step 1: Melting metal raw materials into molten steel;
步骤2：采用连铸或模铸的方法将钢水冶炼成连铸坯或铸锭；Step 2: smelting the molten steel into continuous casting billets or ingots by continuous casting or mold casting;
步骤3：将连铸坯或铸锭锻造开坯，制成锻坯；Step 3: Forging the continuous casting billet or ingot into a forging billet;
步骤4：将锻坯轧制成管坯，通过控制热轧与冷却工艺参数得到高耐蚀油井管钢。Step 4: Roll the forged billet into a tube billet, and obtain high corrosion-resistant oil well pipe steel by controlling hot rolling and cooling process parameters.
在一种可能的设计中，步骤3中，锻造开坯温度为1150～1250℃。In a possible design, in step 3, the forging temperature is 1150-1250°C.
在一种可能的设计中，步骤4中，控制热轧与冷却工艺参数包括：控制开轧温度1050℃以上，终轧温度950℃以上，轧制首道次变形量不大于30％，轧制终道次变形量不大于50％。 In a possible design, in step 4, controlling the hot rolling and cooling process parameters includes: controlling the starting rolling temperature to be above 1050°C, the final rolling temperature to be above 950°C, the deformation in the first rolling pass to be no more than 30%, and the deformation in the final rolling pass to be no more than 50%.
与现有技术相比，本申请有益效果如下：Compared with the prior art, the present invention has the following beneficial effects:
a)本申请的高耐蚀油井管钢精确控制钢中Cr、Ni、Mn、Mo、N元素的质量百分比，结合控轧控冷的热变形工艺，能够获得铁素体+奥氏体+马氏体的混合组织，大幅度提高了油井管钢的耐蚀性及强度。由于本申请的17Cr材料中具有超细马氏体，使材料的抗拉强度优于更高Cr含量的双相不锈钢，实现利用较低Cr含量获得高强度。与现有技术的马氏体不锈钢比，本申请不锈钢中引入铁素体以及奥氏体获得更优良的耐晶间腐蚀性能以及抗H2S应力腐蚀性能。本申请不锈钢中奥氏体含量远高于马氏体不锈钢，马氏体不锈钢很难获得大于20％含量的奥氏体，因此本申请材料具有更好的抗氢脆能力。a) The high corrosion resistant oil well pipe steel of the present application accurately controls the mass percentage of Cr, Ni, Mn, Mo, and N elements in the steel, and combined with the hot deformation process of controlled rolling and controlled cooling, can obtain a mixed structure of ferrite + austenite + martensite, which greatly improves the corrosion resistance and strength of the oil well pipe steel. Since the 17Cr material of the present application has ultrafine martensite, the tensile strength of the material is better than that of duplex stainless steel with a higher Cr content, and high strength is achieved with a lower Cr content. Compared with the martensitic stainless steel of the prior art, the stainless steel of the present application introduces ferrite and austenite to obtain better intergranular corrosion resistance and H2S stress corrosion resistance. The austenite content in the stainless steel of the present application is much higher than that of martensitic stainless steel. It is difficult to obtain an austenite content greater than 20% in martensitic stainless steel, so the material of the present application has better resistance to hydrogen embrittlement.
b)本申请的钢不仅保证了高强度、良好的塑韧性以及优异的耐腐蚀性能，可以保证本申请钢的屈服强度大于600MPa(例如601～648MPa)，抗拉强度大于910MPa(例如911～1010MPa)，伸长率大于22％(例如23％～24％)。(180℃)CO2腐蚀速率0.028g/m2h以下(例如0.0203～0.0275g/m2h)；(200℃)CO2腐蚀速率0.1g/m2h以下(例如0.078～0.099g/m2h)；点腐蚀速率2.5g/m2h以下(例如1.693～2.433g/m2h)；缝隙腐蚀速率5.9g/m2h以下(例如3.303～5.852g/m2h)；H2S应力腐蚀试验均通过。b) The steel of the present application not only ensures high strength, good plasticity and toughness, and excellent corrosion resistance, but also can ensure that the yield strength of the steel of the present application is greater than 600MPa (for example, 601-648MPa), the tensile strength is greater than 910MPa (for example, 911-1010MPa), and the elongation is greater than 22% (for example, 23%-24%). (180℃) CO 2 corrosion rate: 0.028g/m 2 h or less (e.g. 0.0203-0.0275g/m 2 h); (200℃) CO 2 corrosion rate: 0.1g/m 2 h or less (e.g. 0.078-0.099g/m 2 h); pitting corrosion rate: 2.5g/m 2 h or less (e.g. 1.693-2.433g/m 2 h); crevice corrosion rate: 5.9g/m 2 h or less (e.g. 3.303-5.852g/m 2 h); H 2 S stress corrosion test was passed.
c)本申请的钢强韧性好、耐腐蚀性能优良，兼具超级马氏体不锈钢油井管材料的高强度和双相不锈钢的抗应力腐蚀、晶间腐蚀以及抗少量H2S应力腐蚀能力。由于本申请的钢的Cr、Ni含量低，原材料成本与现有技术的超级13Cr马氏体不锈钢相当甚至略低，同时热加工性能好，因此本申请的钢综合成本低、经济、实用。c) The steel of the present application has good toughness and excellent corrosion resistance, and has both the high strength of super martensitic stainless steel oil well pipe materials and the stress corrosion resistance, intergranular corrosion resistance and small amount of H 2 S stress corrosion resistance of duplex stainless steel. Since the Cr and Ni content of the steel of the present application is low, the raw material cost is equivalent to or even slightly lower than that of the super 13Cr martensitic stainless steel in the prior art, and the hot working performance is good, so the steel of the present application has low comprehensive cost, is economical and practical.
本申请的其他特征和优点将在随后的说明书中阐述，并且，部分的从说明书中变得显而易见，或者通过实施本申请而了解。本申请的目的和其他优点可通过在所写的说明书、权利要求书、以及附图中所特别指出的结构来实现和获得。 Other features and advantages of the present application will be described in the subsequent description, and some will become apparent from the description, or will be understood by practicing the present application. The purpose and other advantages of the present application can be realized and obtained by the structures specifically pointed out in the written description, claims, and drawings.
附图说明BRIEF DESCRIPTION OF THE DRAWINGS
附图仅用于示出具体实施例的目的，而并不认为是对本申请的限制，在整个附图中，相同的参考符号表示相同的部件。The accompanying drawings are only for the purpose of illustrating specific embodiments and are not to be considered as limiting the present application. The same reference symbols denote the same components throughout the accompanying drawings.
图1为本申请的实施例1的钢的热轧后显微组织图；FIG1 is a microstructure diagram of the steel after hot rolling of Example 1 of the present application;
图2为本申请的图1中的M处的透射电镜图；FIG2 is a transmission electron microscope image of point M in FIG1 of the present application;
图3为本申请的实施例2的钢的微观组织图；FIG3 is a microstructure diagram of the steel of Example 2 of the present application;
图4为本申请的实施例3的钢的微观组织图；FIG4 is a microstructure diagram of the steel of Example 3 of the present application;
图5为本申请的实施例4的钢的微观组织图；FIG5 is a microstructure diagram of the steel of Example 4 of the present application;
图6为本申请的实施例1的热轧板照片。FIG6 is a photograph of the hot-rolled plate of Example 1 of the present application.
具体实施方式Detailed ways
下面结合附图来具体描述本申请的优选实施例，其中，附图构成本申请一部分，并与本申请的实施例一起用于阐释本申请的原理。The preferred embodiments of the present application are described in detail below in conjunction with the accompanying drawings, wherein the accompanying drawings constitute a part of the present application and are used together with the embodiments of the present application to illustrate the principles of the present application.
本申请提供了一种高耐蚀油井管钢，高耐蚀油井管钢的组分以质量百分比计包括：C：≤0.03％、Cr：17.3％～18.4％、Mo：0.5％～2.0％、Ni：1.0％～2.8％、Mn：1.0％～3.5％、Si：0.1％～0.5％、N：0.1％～0.25％、P：≤0.03％、S：≤0.01％，余量为Fe及不可避免的杂质。The present application provides a high corrosion resistant oil well pipe steel, wherein the components of the high corrosion resistant oil well pipe steel include, by mass percentage, C: ≤0.03%, Cr: 17.3% to 18.4%, Mo: 0.5% to 2.0%, Ni: 1.0% to 2.8%, Mn: 1.0% to 3.5%, Si: 0.1% to 0.5%, N: 0.1% to 0.25%, P: ≤0.03%, S: ≤0.01%, and the balance is Fe and unavoidable impurities.
具体的，Cr+3.3Mo+16N(即PREN)≥26，且60Ni+17Mn-12Mo-800N≤0；其中Cr、Mo、N、Ni、Mn指的是这些元素的质量百分比×100。例如，Cr元素的质量百分比为18.4％，则此处的Cr为18.4。Specifically, Cr+3.3Mo+16N (i.e., PREN) ≥ 26, and 60Ni+17Mn-12Mo-800N ≤ 0; wherein Cr, Mo, N, Ni, and Mn refer to the mass percentage of these elements × 100. For example, the mass percentage of the Cr element is 18.4%, and the Cr here is 18.4.
以下对本申请中所含组分的作用及用量选择作具体说明：The following is a detailed description of the functions and dosage of the components contained in this application:
C：碳的加入虽然可以显著提高钢的硬度强度，但由于碳元素的高扩散能力，容易与Cr结合成M23C6型碳化物，该类型碳化物主要在700～900℃的温度范围内快速析出(≤0.5小时)，或者在550～700℃较长时间保温时析出。碳化物的析出造成局部贫Cr，增加了材料的晶间腐蚀敏感性，恶化耐腐蚀性能，因此，本申请中综合考虑强度和耐腐蚀性的综合效果，控制其含量≤0.03％。 C: Although the addition of carbon can significantly improve the hardness and strength of steel, due to the high diffusion capacity of carbon, it is easy to combine with Cr to form M23C6 type carbide, which is mainly precipitated quickly ( ≤0.5 hours) in the temperature range of 700-900℃, or precipitated when kept at 550-700℃ for a long time. The precipitation of carbides causes local Cr deficiency, increases the intergranular corrosion sensitivity of the material, and deteriorates the corrosion resistance. Therefore, in this application, the comprehensive effects of strength and corrosion resistance are comprehensively considered, and its content is controlled to be ≤0.03%.
Cr：保证不锈钢耐腐蚀性能的主要元素，同时也是铁素体形成元素，Cr含量控制不当会使组织中铁素体含量增加，降低强度，综合考虑控制其含量17.3％～18.4％。Cr: The main element to ensure the corrosion resistance of stainless steel. It is also a ferrite-forming element. Improper control of Cr content will increase the ferrite content in the organization and reduce the strength. Considering comprehensive considerations, its content is controlled at 17.3% to 18.4%.
Ni：是强烈形成并稳定奥氏体且扩大奥氏体相区的元素，Ni是提高不锈钢韧性和耐还原性介质腐蚀性能的元素，Ni还是提高奥氏体相耐多种介质穿晶型应力腐蚀的重要元素，与此同时，相对于Mn元素，Ni元素可以降低奥氏体相冷加工硬化倾向，在考虑成本控制的情况下本申请控制其含量在1.0％～2.8％。Ni: It is an element that strongly forms and stabilizes austenite and expands the austenite phase region. Ni is an element that improves the toughness and corrosion resistance of stainless steel in reducing media. Ni is also an important element for improving the resistance of austenite phase to transgranular stress corrosion in various media. At the same time, compared with Mn element, Ni element can reduce the cold work hardening tendency of austenite phase. Considering cost control, this application controls its content within 1.0% to 2.8%.
Mn：可以提高N在钢中的溶解度并抑制有害相氮化铬的析出，但Mn降低不锈钢的韧性，相对于Ni而言，Mn是一个的奥氏体形成元素，Mn对不锈钢奥氏体相及材料整体的硬化效果有区别，因此本申请控制其含量在1.0％～3.5％。Mn: It can increase the solubility of N in steel and inhibit the precipitation of harmful phase chromium nitride, but Mn reduces the toughness of stainless steel. Compared with Ni, Mn is an austenite-forming element. Mn has different hardening effects on the austenite phase of stainless steel and the overall material. Therefore, this application controls its content within 1.0% to 3.5%.
Mo：除提高不锈钢在氧化介质中的耐腐蚀性能，其对提高不锈钢耐还原性介质腐蚀性能有良好作用，同时，为了保证耐点蚀性能，Cr、Mo等提高PREN值的合金元素不宜过低，同时还需要考虑到合金成本控制和相平衡，综合考虑，控制其含量0.5％～2.0％。Mo: In addition to improving the corrosion resistance of stainless steel in oxidizing media, it also has a good effect on improving the corrosion resistance of stainless steel in reducing media. At the same time, in order to ensure pitting resistance, alloy elements such as Cr and Mo that increase the PREN value should not be too low. At the same time, alloy cost control and phase balance must also be considered. Comprehensively considered, its content is controlled to 0.5% to 2.0%.
Si：在冶炼过程中作为脱氧剂加入，可起到脱氧的效果，过高添加会恶化材料的耐晶间腐蚀性能。本申请控制其含量在0.1％～0.5％。Si: Si is added as a deoxidizer during the smelting process to achieve a deoxidation effect. Too much addition will deteriorate the intergranular corrosion resistance of the material. The content of Si is controlled within 0.1% to 0.5% in this application.
N：和Ni一样，是强烈形成并稳定奥氏体且扩大奥氏体相区的元素，N还能显著提高不锈钢中奥氏体相的耐点蚀性能，从而提高不锈钢整体耐点蚀性能，在一些介质中，N对不锈钢耐应力性能有良好的作用，且存在一个最佳值，进一步提高N含量，其耐应力腐蚀性能下降。N同时是一个比较经济的合金元素，但N降低不锈钢的热加工性能，因此，本申请控制其含量在0.1％～0.25％。N: Like Ni, it is an element that strongly forms and stabilizes austenite and expands the austenite phase. N can also significantly improve the pitting corrosion resistance of the austenite phase in stainless steel, thereby improving the overall pitting corrosion resistance of stainless steel. In some media, N has a good effect on the stress resistance of stainless steel, and there is an optimal value. Further increasing the N content will reduce its stress corrosion resistance. N is also a relatively economical alloying element, but N reduces the hot working performance of stainless steel. Therefore, this application controls its content to 0.1% to 0.25%.
S：会显著降低钢的热加工性能，且容易与Mn反应生成MnS夹杂，降低材料的耐点蚀性能和耐缝隙腐蚀性能。故而控制其含量≤0.01％。S: It will significantly reduce the hot working performance of steel and easily react with Mn to form MnS inclusions, which will reduce the material's resistance to pitting corrosion and crevice corrosion. Therefore, its content is controlled to ≤ 0.01%.
P：属于有害杂质元素，不但会恶化材料的塑性，也会降低材料的 耐腐蚀性能，故而控制其含量≤0.03％。P: It is a harmful impurity element, which will not only deteriorate the plasticity of the material, but also reduce the Corrosion resistance, so the content is controlled ≤ 0.03%.
具体的，本申请中综合考虑耐腐蚀性能的保证、合金元素匹配带来的原材料成本、合金元素匹配导致的有害相析出以及热加工成材率导致的成本变化等3个方面考虑，除钢中主要合金元素Cr、Ni、Mn、N单个元素含量的控制外，为保证耐蚀性，控制Cr+3.3Mo+16N≥26，为使有害相的最高析出温度低于750℃，保证材料具有良好的热加工性能，同时考虑三相比例能够在900～1180℃之间的热加工过程中可控，需要控制Ni、Mn、Mo、N元素含量满足：60Ni+17Mn-12Mo-800N≤0。Specifically, the present application comprehensively considers three aspects: guarantee of corrosion resistance, raw material cost caused by alloy element matching, precipitation of harmful phases caused by alloy element matching, and cost change caused by hot working yield. In addition to controlling the content of individual elements of the main alloying elements Cr, Ni, Mn, and N in steel, in order to ensure corrosion resistance, Cr+3.3Mo+16N≥26 is controlled. In order to make the maximum precipitation temperature of harmful phases lower than 750°C and ensure that the material has good hot working properties, and considering that the three-phase ratio can be controllable during hot working between 900 and 1180°C, it is necessary to control the content of Ni, Mn, Mo, and N elements to meet the following requirements: 60Ni+17Mn-12Mo-800N≤0.
为了进一步改善上述高耐蚀油井管钢的综合性能，上述高耐蚀油井管钢的组分以质量百分比计可以为：C：0.01％～0.03％、Cr：17.4％～18.4％、Mo：1.0％～2.0％、Ni：1.0％～2.7％、Mn：1.4％～3.2％、Si：0.1％～0.5％、N：0.13％～0.25％、P：≤0.03％、S：≤0.01％，余量为Fe及不可避免的杂质。其中，Cr+3.3Mo+16N(即PREN)为26.1～27.8，且60Ni+17Mn-12Mo-800N≤-0.42。In order to further improve the comprehensive performance of the above-mentioned high corrosion resistant oil well pipe steel, the composition of the above-mentioned high corrosion resistant oil well pipe steel can be calculated by mass percentage: C: 0.01% to 0.03%, Cr: 17.4% to 18.4%, Mo: 1.0% to 2.0%, Ni: 1.0% to 2.7%, Mn: 1.4% to 3.2%, Si: 0.1% to 0.5%, N: 0.13% to 0.25%, P: ≤0.03%, S: ≤0.01%, and the balance is Fe and unavoidable impurities. Among them, Cr+3.3Mo+16N (i.e., PREN) is 26.1 to 27.8, and 60Ni+17Mn-12Mo-800N≤-0.42.
具体的，上述高耐蚀油井管钢的微观组织为铁素体+奥氏体+马氏体的混合组织，其中，奥氏体的体积百分含量为20％～40％(例如20％～35％)，马氏体的体积百分含量为10％～40％(例如30％～40％)，马氏体呈超细的片状分散在奥氏体中，与奥氏体层叠交替，互相分割，使得奥氏体具有更小的晶粒尺寸(例如奥氏体晶粒尺寸＜3μm)，马氏体片的厚度小于100nm。Specifically, the microstructure of the above-mentioned high corrosion-resistant oil well pipe steel is a mixed structure of ferrite + austenite + martensite, wherein the volume percentage of austenite is 20% to 40% (for example, 20% to 35%), and the volume percentage of martensite is 10% to 40% (for example, 30% to 40%). The martensite is dispersed in the austenite in the form of ultrafine sheets, and is alternately stacked with the austenite and divided from each other, so that the austenite has a smaller grain size (for example, the austenite grain size is <3μm), and the thickness of the martensite sheet is less than 100nm.
与现有技术相比，本申请的高耐蚀油井管钢为三相组织，本申请的钢具有低Cr、低合金元素含量获得更高强度的特点，可同时具备高强度、耐晶间腐蚀、应力腐蚀以及高韧性及良好的焊接性能等特点，具备优异的综合性能。同时马氏体奥氏体的复合结构可以提高组织中的界面密度，从而获得优于传统双相不锈钢的高强度力学性能。其在常规热加工温度区间内(900-1180℃)均衡的相比例带来极佳的热加工性能，热加工后多相复合的组织形式在保证一定冷加工性能的同时拥有优于单相马氏体不锈钢的耐蚀性能。Compared with the prior art, the high corrosion-resistant oil well pipe steel of the present application is a three-phase structure. The steel of the present application has the characteristics of low Cr and low alloy element content to obtain higher strength. It can also have the characteristics of high strength, resistance to intergranular corrosion, stress corrosion, high toughness and good welding performance, and has excellent comprehensive performance. At the same time, the composite structure of martensite and austenite can increase the interface density in the organization, thereby obtaining high-strength mechanical properties that are superior to traditional duplex stainless steel. Its balanced phase ratio in the conventional hot working temperature range (900-1180°C) brings excellent hot working performance. The multi-phase composite organizational form after hot working has better corrosion resistance than single-phase martensitic stainless steel while ensuring certain cold working performance.
本申请还提供了上述高耐蚀油井管钢的制备方法，包括： The present application also provides a method for preparing the above-mentioned highly corrosion-resistant oil well pipe steel, comprising:
步骤1：将金属原材料熔炼成钢水；Step 1: Melting metal raw materials into molten steel;
步骤2：采用连铸或模铸的方法将钢水冶炼成连铸坯或铸锭；Step 2: smelting the molten steel into continuous casting billets or ingots by continuous casting or mold casting;
步骤3：将连铸坯或铸锭在1150～1250℃下加热，进行锻造开坯，制成锻坯；Step 3: heating the continuous casting billet or ingot at 1150-1250° C., forging and opening the billet to form a forging billet;
步骤4：将锻坯在1050～1250℃下加热，轧制成管坯，通过控制热轧与冷却工艺参数得到高耐蚀油井管钢。其中，高耐蚀油井管钢的三相组织含量为：马氏体含量10％～40％，奥氏体含量20％～40％，其余为铁素体。Step 4: Heat the forged billet at 1050-1250°C, roll it into a tube billet, and obtain high corrosion resistant oil well pipe steel by controlling the hot rolling and cooling process parameters. The three-phase structure content of the high corrosion resistant oil well pipe steel is: martensite content 10%-40%, austenite content 20%-40%, and the rest is ferrite.
具体的，上述步骤1和步骤2中，采用转炉或电炉冶炼、LF精炼、铸成铸坯。Specifically, in the above steps 1 and 2, converter or electric furnace smelting, LF refining and casting into ingots are adopted.
具体的，上述步骤3中，锻造开坯温度为1150～1250℃，这是因为本申请材料在高于800℃时为铁素体+奥氏体两相，两相比例随加热温度变化，加热温度越高，铁素体含量越多，相应的奥氏体含量降低。选择该温度范围加热同时保证了有害析出相的充分回溶，也使材料中铁素体相含量大于70％，使钢在热塑性更好的接近单相区锻造开坯，避免了由于铁素体和奥氏体两种相的热变形能力的不同，导致锻造过程两相变形不协调引起锻造开裂。Specifically, in the above step 3, the forging temperature is 1150-1250°C. This is because the material of the present application is a two-phase ferrite + austenite when it is higher than 800°C. The ratio of the two phases changes with the heating temperature. The higher the heating temperature, the more ferrite content, and the corresponding austenite content decreases. Selecting this temperature range for heating ensures the full dissolution of harmful precipitated phases, and also makes the ferrite phase content in the material greater than 70%, so that the steel is forged in a single-phase region with better thermoplasticity, avoiding the difference in the thermal deformation capacity of the two phases of ferrite and austenite, which leads to the uncoordinated deformation of the two phases in the forging process and causes forging cracking.
具体的，上述步骤4中，热轧成管坯后水冷到室温，避免有害相的析出。Specifically, in the above step 4, the tube is hot-rolled and then water-cooled to room temperature to avoid the precipitation of harmful phases.
具体的，上述步骤4中，由于本申请的油井管钢具有优良的热加工窗口，控制热轧与冷却工艺参数包括：控制开轧温度1050℃以上(例如1050～1200℃)，终轧温度950℃以上(例如950℃～1050℃)，轧制首道次变形量不大于30％，轧制终道次变形量不大于50％。Specifically, in the above step 4, since the oil well pipe steel of the present application has an excellent hot working window, controlling the hot rolling and cooling process parameters includes: controlling the starting rolling temperature to be above 1050° C. (e.g., 1050-1200° C.), the final rolling temperature to be above 950° C. (e.g., 950° C.-1050° C.), the deformation amount of the first rolling pass to be no more than 30%, and the deformation amount of the final rolling pass to be no more than 50%.
与现有技术相比，本申请的高耐蚀油井管钢精确控制钢中Cr、Ni、Mn、Mo、N元素的质量百分比，结合控轧控冷的热变形工艺，能够获得铁素体+奥氏体+马氏体的混合组织，大幅度提高了油井管钢的耐蚀性及强韧性。在不锈钢中，Cr含量增加可提高材料的强度，但是由于本申请的17Cr材料中具有超细马氏体，使材料的抗拉强度优于更高Cr含量 的双相不锈钢。本申请17Cr三相组织不锈钢与现有技术的双相不锈钢比，通过控制Cr、Ni、Mn、Mo、N的含量组合，在热轧后获得马氏体含量可调节的三相组织，实现利用较低Cr含量获得高强度。与现有技术的马氏体不锈钢比，本申请不锈钢中引入铁素体以及奥氏体获得更优良的耐晶间腐蚀性能以及抗H2S应力腐蚀性能。本申请不锈钢中奥氏体含量远高于马氏体不锈钢，马氏体不锈钢很难获得大于20％含量的奥氏体，因此本申请材料具有更好的抗氢脆能力。Compared with the prior art, the high corrosion resistant oil well pipe steel of the present application accurately controls the mass percentage of Cr, Ni, Mn, Mo, and N elements in the steel, and combines the hot deformation process of controlled rolling and controlled cooling to obtain a mixed structure of ferrite + austenite + martensite, which greatly improves the corrosion resistance and toughness of the oil well pipe steel. In stainless steel, increasing the Cr content can increase the strength of the material, but because the 17Cr material of the present application has ultrafine martensite, the tensile strength of the material is better than that of the material with a higher Cr content. Duplex stainless steel. Compared with the duplex stainless steel in the prior art, the 17Cr three-phase stainless steel in the present application controls the content combination of Cr, Ni, Mn, Mo, and N, and obtains a three-phase structure with adjustable martensite content after hot rolling, thereby achieving high strength with a lower Cr content. Compared with the martensitic stainless steel in the prior art, ferrite and austenite are introduced into the stainless steel in the present application to obtain better intergranular corrosion resistance and H2S stress corrosion resistance. The austenite content in the stainless steel in the present application is much higher than that in martensitic stainless steel. It is difficult to obtain an austenite content greater than 20% in martensitic stainless steel. Therefore, the material in the present application has better resistance to hydrogen embrittlement.
本申请的钢不仅保证了高强度、良好的塑韧性以及优异的耐腐蚀性能，可以保证本申请钢的屈服强度大于600MPa(例如601～648MPa)，抗拉强度大于910MPa(例如911～1010MPa)，伸长率大于22％(例如23％～24％)。(180℃)CO2腐蚀速率0.028g/m2h以下(例如0.0203～0.0275g/m2h)；(200℃)CO2腐蚀速率0.1g/m2h以下(例如0.078～0.099g/m2h)；点腐蚀速率2.5g/m2h以下(例如1.693～2.433g/m2h)；缝隙腐蚀速率5.9g/m2h以下(例如3.303～5.852g/m2h)；H2S应力腐蚀试验均通过。The steel of the present application not only ensures high strength, good plasticity and toughness, and excellent corrosion resistance, but can also ensure that the yield strength of the steel of the present application is greater than 600MPa (for example, 601-648MPa), the tensile strength is greater than 910MPa (for example, 911-1010MPa), and the elongation is greater than 22% (for example, 23%-24%). (180℃) CO 2 corrosion rate: 0.028g/m 2 h or less (e.g. 0.0203-0.0275g/m 2 h); (200℃) CO 2 corrosion rate: 0.1g/m 2 h or less (e.g. 0.078-0.099g/m 2 h); pitting corrosion rate: 2.5g/m 2 h or less (e.g. 1.693-2.433g/m 2 h); crevice corrosion rate: 5.9g/m 2 h or less (e.g. 3.303-5.852g/m 2 h); H 2 S stress corrosion test was passed.
本申请的钢强韧性好、耐腐蚀性能优良，兼具超级马氏体不锈钢油井管材料的高强度和双相不锈钢的抗应力腐蚀、晶间腐蚀以及抗少量H2S应力腐蚀能力。由于本申请的钢的Cr、Ni含量低，原材料成本与现有技术的超级13Cr马氏体不锈钢相当甚至略低，同时热加工性能好，因此本申请的钢综合成本低、经济、实用。The steel of the present application has good toughness and excellent corrosion resistance, and has both the high strength of super martensitic stainless steel oil well pipe materials and the stress corrosion resistance, intergranular corrosion resistance and small amount of H 2 S stress corrosion resistance of duplex stainless steel. Since the Cr and Ni content of the steel of the present application is low, the raw material cost is equivalent to or even slightly lower than that of the super 13Cr martensitic stainless steel of the prior art, and the hot working performance is good, so the steel of the present application has low comprehensive cost, is economical and practical.
实施例1-4Examples 1-4
下面以具体的实施例与对比例来展示本申请钢的成分和工艺参数精确控制的优势。选择13Cr作为腐蚀性能的比较对象。The advantages of precise control of the composition and process parameters of the steel of the present application are demonstrated below with specific examples and comparative examples. 13Cr is selected as a comparison object for corrosion performance.
本申请的实施例1-4提供了一种高耐蚀油井管钢及其制备方法，实施例1-4钢的化学成分见表1。Examples 1-4 of the present application provide a highly corrosion-resistant oil well pipe steel and a preparation method thereof. The chemical compositions of the steels of Examples 1-4 are shown in Table 1.
实施例1的制备方法包括：The preparation method of Example 1 comprises:
步骤1：将金属原材料熔炼成钢水；采用模铸的方法将钢水冶炼成 钢锭，得到铸坯；Step 1: Melt the metal raw materials into molten steel; Use the die casting method to smelt the molten steel into Ingot, to obtain casting billet;
步骤2：将铸坯加热至1150℃保温2h后，进行锻造开坯，制成锻坯；Step 2: After heating the ingot to 1150°C and keeping the temperature for 2 hours, forging and opening the ingot to form a forging ingot;
步骤3：将锻坯在1050℃下保温2h，轧制成管坯，通过控制热轧与冷却工艺参数(首道次变形量25％，终轧道次变形量48％，终轧板厚控制在3.5mm左右，水冷)，控制终轧温度960℃调整三相组织含量，铁素体含量40％，马氏体含量40％，奥氏体含量20％。Step 3: Keep the forging billet at 1050°C for 2h and roll it into a tube billet. By controlling the hot rolling and cooling process parameters (the deformation amount of the first pass is 25%, the deformation amount of the final rolling pass is 48%, the final rolling plate thickness is controlled at about 3.5mm, and water cooling), the final rolling temperature is controlled at 960°C to adjust the three-phase structure content, the ferrite content is 40%, the martensite content is 40%, and the austenite content is 20%.
实施例2的制备方法包括：The preparation method of Example 2 comprises:
步骤1：将金属原材料熔炼成钢水；采用模铸的方法将钢水冶炼成钢锭，得到铸坯；Step 1: Melting metal raw materials into molten steel; using a die casting method to smelt the molten steel into steel ingots to obtain ingots;
步骤2：将铸坯加热至1180℃保温1.5h后，进行锻造开坯，制成锻坯；Step 2: After heating the ingot to 1180°C and keeping the temperature for 1.5 hours, forging and opening the ingot to form a forging ingot;
步骤3：将锻坯在1150℃下保温2h，轧制成管坯，通过控制热轧与冷却工艺参数(首道次变形量28％，终轧道次变形量45％，终轧板厚控制在3.5mm左右，水冷)，通过控制终轧温度1000℃调整三相组织含量，铁素体含量45％，马氏体含量30％，奥氏体含量25％。Step 3: Keep the forging billet at 1150°C for 2h and roll it into a tube billet. By controlling the hot rolling and cooling process parameters (the deformation amount of the first pass is 28%, the deformation amount of the final rolling pass is 45%, the final rolling plate thickness is controlled at about 3.5mm, and water cooling), and by controlling the final rolling temperature at 1000°C, the three-phase structure content is adjusted to 45% ferrite, 30% martensite, and 25% austenite.
实施例3的制备方法包括：The preparation method of Example 3 comprises:
步骤1：将金属原材料熔炼成钢水；采用模铸的方法将钢水冶炼成钢锭，得到铸坯；Step 1: Melting metal raw materials into molten steel; using a die casting method to smelt the molten steel into steel ingots to obtain ingots;
步骤2：将铸坯加热至1200℃保温1h后，进行锻造开坯，制成锻坯；Step 2: After heating the ingot to 1200°C and keeping the temperature for 1 hour, forging and opening the ingot to make a forging ingot;
步骤3：将锻坯在1200℃下保温2h，轧制成管坯，通过控制热轧与冷却工艺参数(首道次变形量23％，终轧道次变形量46％，终轧板厚控制在3.5mm左右，水冷)，通过控制终轧温度1050℃(调整三相组织含量，铁素体含量40％，马氏体含量30％，奥氏体含量30％。Step 3: The forged billet is kept at 1200℃ for 2h and rolled into a tube billet. By controlling the hot rolling and cooling process parameters (the deformation of the first pass is 23%, the deformation of the final rolling pass is 46%, the final rolling thickness is controlled at about 3.5mm, and water cooling), the final rolling temperature is controlled at 1050℃ (the three-phase structure content is adjusted to 40% ferrite, 30% martensite, and 30% austenite.
实施例4的制备方法包括：The preparation method of Example 4 comprises:
步骤1：将金属原材料熔炼成钢水；采用模铸的方法将钢水冶炼成 铸锭，得到铸坯；Step 1: Melt the metal raw materials into molten steel; Use the die casting method to smelt the molten steel into Casting ingots to obtain billets;
步骤2：将铸锭加热至1250℃保温1h后，进行锻造开坯，制成锻坯；Step 2: After heating the ingot to 1250°C and keeping it for 1 hour, forging and blanking are performed to form a forging billet;
步骤3：将锻坯在1200℃下保温2h，轧制成管坯，通过控制热轧与冷却工艺参数(首道次变形量26％，终轧道次变形量45％，终轧板厚控制在3.5mm左右，水冷)，通过控制终轧温度1050℃调整三相组织含量，铁素体含量35％，马氏体含量30％，奥氏体含量35％。Step 3: Keep the forging billet at 1200°C for 2h and roll it into a tube billet. By controlling the hot rolling and cooling process parameters (the deformation amount of the first pass is 26%, the deformation amount of the final rolling pass is 45%, the final rolled plate thickness is controlled at about 3.5mm, and water cooling), and by controlling the final rolling temperature at 1050°C, the three-phase structure content is adjusted to 35% ferrite, 30% martensite, and 35% austenite.
实施例1-4的具体工艺参数见表2，实施例1-4的力学性能见表3，图1为本申请的实施例1的钢的微观组织图，图2是本申请的图1中的M处的透射电镜图，其中左上角是A处马氏体与奥氏体基体的衍射斑，可以证明黑色马氏体片的晶体结构以及马氏体片的厚度＜100nm。The specific process parameters of Examples 1-4 are shown in Table 2, the mechanical properties of Examples 1-4 are shown in Table 3, FIG1 is a microstructure diagram of the steel of Example 1 of the present application, and FIG2 is a transmission electron microscope image of point M in FIG1 of the present application, wherein the upper left corner is the diffraction spot of the martensite and austenite matrix at point A, which can prove the crystal structure of the black martensite sheet and the thickness of the martensite sheet is less than 100 nm.
图3-图5分别为本申请的实施例2-4的钢的微观组织图；实施例1-4的微观组织如下表4所示。本申请的高耐蚀油井管钢的微观组织为铁素体+奥氏体+马氏体的混合组织，其中，奥氏体的体积百分含量为20％～40％(例如20％～35％)，马氏体的体积百分含量为10％～40％(例如30％～40％)，马氏体呈超细的片状分散在奥氏体中，与奥氏体层叠交替，互相分割，使得奥氏体具有更小的晶粒尺寸(例如奥氏体晶粒尺寸＜3μm)，马氏体片的厚度小于100nm。Figures 3 to 5 are respectively microstructure diagrams of the steel of Examples 2 to 4 of the present application; the microstructures of Examples 1 to 4 are shown in Table 4 below. The microstructure of the high corrosion resistant oil well pipe steel of the present application is a mixed structure of ferrite + austenite + martensite, wherein the volume percentage of austenite is 20% to 40% (e.g., 20% to 35%), and the volume percentage of martensite is 10% to 40% (e.g., 30% to 40%), and the martensite is dispersed in the austenite in the form of ultrafine flakes, alternately stacked with austenite, and divided from each other, so that the austenite has a smaller grain size (e.g., austenite grain size <3 μm), and the thickness of the martensite sheet is less than 100 nm.
表1实施例1-4的化学成分wt％
Table 1 Chemical composition of Examples 1-4 (wt%)
表2实施例1-4的具体工艺参数
Table 2 Specific process parameters of Examples 1-4
表3实施例1-4的力学性能
Table 3 Mechanical properties of Examples 1-4
表4实施例1-4的钢的微观组织

Table 4 Microstructure of steel of Examples 1-4

为了说明本申请的钢的耐蚀性能，将实施例1-4的钢通过5种不同条件对耐蚀性能进行衡量，并与相同测试条件下的13Cr进行对比，通过此实验来评价本申请的钢在不同腐蚀环境中的耐蚀性能。耐蚀试验的结果如表5所示，相应的试验条件如下所述：In order to illustrate the corrosion resistance of the steel of the present application, the corrosion resistance of the steel of Examples 1-4 was measured under 5 different conditions and compared with 13Cr under the same test conditions. This experiment was used to evaluate the corrosion resistance of the steel of the present application in different corrosive environments. The results of the corrosion test are shown in Table 5, and the corresponding test conditions are as follows:
(180℃或200℃)CO2腐蚀速率的腐蚀条件如下：(180℃ or 200℃) The corrosion conditions of CO 2 corrosion rate are as follows:
1、介质(地层水)mg/L：CO3 2-/0，HCO3 -/189,OH-/0,Cl-/128000,SO4 2-/430,Ca2+/8310,Mg2+/561,K+/6620,Na+/76500)；1. Medium (formation water) mg/L: CO 3 2- /0, HCO 3 - /189, OH - /0, Cl - /128000, SO 4 2- /430, Ca 2+ /8310, Mg 2+ /561, K + /6620, Na + /76500);
2、CO2分压：4.48MPa，试验总压：10MPa；2. CO2 partial pressure: 4.48MPa, total test pressure: 10MPa;
3、试验温度180℃或200℃；3. Test temperature: 180℃ or 200℃;
4、试验时间720小时。4. Test time: 720 hours.
点腐蚀速率的腐蚀条件如下：The corrosion conditions for pitting corrosion rate are as follows:
1、试验温度：22±2℃；1. Test temperature: 22±2℃;
2、介质：100g试剂级三氯化铁FeCl3·6H2O溶于900mL IV型试剂级水(质量比约6％)；2. Medium: 100g reagent grade ferric chloride FeCl 3 ·6H 2 O is dissolved in 900mL IV type reagent grade water (mass ratio about 6%);
3、试验时间：72小时；3. Test time: 72 hours;
4、试样尺寸：50×25×3mm打磨至2000#砂纸。4. Sample size: 50×25×3mm, polished to 2000# sandpaper.
缝隙腐蚀速率的腐蚀条件如下：The corrosion conditions for crevice corrosion rate are as follows:
1、试验温度为22±2℃；1. The test temperature is 22±2℃;
2、100g试剂级三氯化铁FeCl3·6H2O溶于900mL IV型试剂级水(质量比约6％)；2. Dissolve 100g reagent grade ferric chloride FeCl 3 ·6H 2 O in 900mL IV reagent grade water (mass ratio about 6%);
3、试验时间：72小时；3. Test time: 72 hours;
4、试样尺寸：50×25×3mm打磨至2000#砂纸。4. Sample size: 50×25×3mm, polished to 2000# sandpaper.
H2S应力腐蚀试验的腐蚀条件如下：The corrosion conditions of H2S stress corrosion test are as follows:
1、试验温度为22±2℃；1. The test temperature is 22±2℃;
2、50g NaCl、25g[23.8mL]CH3COOH、4.1g CH3COONa溶于921mL IV型试剂级水(质量比约5wt％的氯化钠、2.5wt％的冰醋酸和0.41wt％的醋酸钠)； 2. 50 g NaCl, 25 g [23.8 mL] CH 3 COOH, and 4.1 g CH 3 COONa were dissolved in 921 mL IV reagent grade water (mass ratio of about 5 wt % sodium chloride, 2.5 wt % glacial acetic acid, and 0.41 wt % sodium acetate);
3、试验时间：720小时；3. Test time: 720 hours;
4、试样尺寸：50×5×2mm打磨至2000#砂纸；4. Sample size: 50×5×2mm, polished to 2000# sandpaper;
5、四点弯曲试验，加载力为80％屈服应力。5. Four-point bending test, loading force is 80% yield stress.
从表5可知，实施例1-4的高耐蚀油井管钢的(180℃)CO2腐蚀速率0.028g/m2h以下(例如0.0203～0.0275g/m2h)；(200℃)CO2腐蚀速率0.1g/m2h以下(例如0.078～0.099g/m2h)；点腐蚀速率2.5g/m2h以下(例如1.693～2.433g/m2h)；缝隙腐蚀速率5.9g/m2h以下(例如3.303～5.852g/m2h)；H2S应力腐蚀试验均通过。本申请的实施例1-4的耐蚀性均优于13Cr，特别是200℃时的耐CO2腐蚀性能，本申请远优于超级13Cr，可在更苛刻的环境使用，即适用更大井深的环境使用。如图5所示为实施例1的H2S应力腐蚀试验结果图。As can be seen from Table 5, the (180°C) CO 2 corrosion rate of the high corrosion resistant oil well pipe steel of Examples 1-4 is less than 0.028 g/m 2 h (e.g., 0.0203-0.0275 g/m 2 h); the (200°C) CO 2 corrosion rate is less than 0.1 g/m 2 h (e.g., 0.078-0.099 g/m 2 h); the pitting corrosion rate is less than 2.5 g/m 2 h (e.g., 1.693-2.433 g/m 2 h); the crevice corrosion rate is less than 5.9 g/m 2 h (e.g., 3.303-5.852 g/m 2 h); and the H 2 S stress corrosion test is passed. The corrosion resistance of Examples 1-4 of the present application is better than that of 13Cr, especially the CO 2 corrosion resistance at 200°C. The present application is far better than super 13Cr and can be used in more demanding environments, that is, suitable for use in environments with greater well depths. FIG. 5 is a diagram showing the results of the H 2 S stress corrosion test of Example 1. FIG.
表5腐蚀试验数据
Table 5 Corrosion test data
为了说明本申请钢的热加工性能，对实施例1-4的钢热轧后板材的边缘质量进行统计，以实施例1为例。图6所示为实施例1的热轧板照片，可见边缘无开裂，本申请的实施例的钢在实际生产过程中的成材率达到90％以上。In order to illustrate the hot working performance of the steel of the present application, the edge quality of the steel plates after hot rolling of Examples 1-4 is statistically analyzed, taking Example 1 as an example. FIG6 shows a photo of the hot rolled plate of Example 1, showing that there is no cracking at the edge, and the yield rate of the steel of the examples of the present application in the actual production process reaches more than 90%.
发明人在研究中进行了大量的深入研究，现在将其中一些效果不好 的方案作为对比例列举如下：The inventor has conducted a lot of in-depth research in the research and now will introduce some of the poor results The scheme is listed as a comparative example as follows:
对比例1Comparative Example 1
本对比例提供了一种耐蚀油井管钢及其制备方法，本对比例的耐蚀油井管钢为13Cr，采用目前13Cr的成熟工艺制备。本对比例的耐蚀油井管钢的成分为C：0.03％，Cr：13％，Ni：5％，Mo：2％，Mn：0.5％，Si：0.5％，制备方法：经1150℃加热锻造后，水冷，再重新加热到860℃保温2h，淬火，620℃回火1小时。This comparative example provides a corrosion-resistant oil well pipe steel and a preparation method thereof. The corrosion-resistant oil well pipe steel of this comparative example is 13Cr and is prepared by the current mature process of 13Cr. The composition of the corrosion-resistant oil well pipe steel of this comparative example is C: 0.03%, Cr: 13%, Ni: 5%, Mo: 2%, Mn: 0.5%, Si: 0.5%, and the preparation method is: after heating and forging at 1150°C, water cooling, and then reheating to 860°C for 2h, quenching, and tempering at 620°C for 1 hour.
本对比例的钢的微观组织为马氏体(93％)+奥氏体(7％)。力学性能如上表3所示，耐蚀性能结果如上表5所示。The microstructure of the steel of this comparative example is martensite (93%) + austenite (7%). The mechanical properties are shown in Table 3 above, and the corrosion resistance results are shown in Table 5 above.
对比例2Comparative Example 2
本对比例提供了一种耐蚀油井管钢及其制备方法，本对比例的耐蚀油井管钢的成分为C：0.03％，Cr：16％，Mo：1.21％，N：0.22％，Mn：2.11％，Si：0.5％，制备方法与实施例1相同。This comparative example provides a corrosion-resistant oil well pipe steel and a preparation method thereof. The corrosion-resistant oil well pipe steel of this comparative example has the following components: C: 0.03%, Cr: 16%, Mo: 1.21%, N: 0.22%, Mn: 2.11%, and Si: 0.5%. The preparation method is the same as that of Example 1.
本对比例的钢的微观组织为铁素体(15％)+马氏体(65％)+奥氏体(20％)。力学性能能如表3所示，耐蚀性能结果如表5所示。The microstructure of the steel of this comparative example is ferrite (15%) + martensite (65%) + austenite (20%). The mechanical properties are shown in Table 3, and the corrosion resistance results are shown in Table 5.
对比例3Comparative Example 3
本对比例提供了一种耐蚀油井管钢及其制备方法，本对比例的耐蚀油井管钢的成分为C：0.04％，Cr：16.5％，Ni：1.12％，Mo：1.32％，N：0.16％，Mn：2.82％，Si：0.5％，制备方法与实施例1相同。This comparative example provides a corrosion-resistant oil well pipe steel and a preparation method thereof. The corrosion-resistant oil well pipe steel of this comparative example has the following components: C: 0.04%, Cr: 16.5%, Ni: 1.12%, Mo: 1.32%, N: 0.16%, Mn: 2.82%, and Si: 0.5%. The preparation method is the same as that of Example 1.
本对比例的钢的微观组织为铁素体(20％)+马氏体(60％)+奥氏体(20％)。力学性能如表3所示，耐蚀性能结果如表5所示。The microstructure of the steel of this comparative example is ferrite (20%) + martensite (60%) + austenite (20%). The mechanical properties are shown in Table 3, and the corrosion resistance results are shown in Table 5.
对比实施例和对比例可见，本申请的高耐蚀油井管钢精确控制钢中Cr、Ni、Mn、Mo、N元素的质量百分比，结合控轧控冷的热变形工艺，能够获得铁素体+奥氏体+马氏体的混合组织，大幅度提高了油井管钢的耐蚀性及强韧性，原材料成本与现有技术的超级13Cr马氏体不锈钢相当甚至略低，同时热加工性能好，本申请的高耐蚀油井管钢的耐蚀性能优于超级13Cr马氏体不锈钢，因此本申请的钢综合成本低、经济、实用。 By comparing the embodiments and comparative examples, it can be seen that the high corrosion-resistant oil well pipe steel of the present application accurately controls the mass percentages of Cr, Ni, Mn, Mo, and N elements in the steel, and combines the hot deformation process of controlled rolling and controlled cooling to obtain a mixed structure of ferrite + austenite + martensite, which greatly improves the corrosion resistance and toughness of the oil well pipe steel. The raw material cost is equivalent to or even slightly lower than that of the super 13Cr martensitic stainless steel in the prior art, and the hot processing performance is good. The corrosion resistance of the high corrosion-resistant oil well pipe steel of the present application is better than that of the super 13Cr martensitic stainless steel. Therefore, the steel of the present application has low comprehensive cost, is economical, and is practical.
以上所述，仅为本申请较佳的具体实施方式，但本申请的保护范围并不局限于此，任何熟悉本技术领域的技术人员在本申请揭露的技术范围内，可轻易想到的变化或替换，都应涵盖在本申请的保护范围之内。 The above is only a preferred specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any changes or substitutions that can be easily conceived by any technician familiar with the technical field within the technical scope disclosed in the present application should be covered within the protection scope of the present application.

Claims (10)

  1. 一种高耐蚀油井管钢，其特征在于，所述高耐蚀油井管钢的组分以质量百分比计包括：C：≤0.03％、Cr：17.3％～18.4％、Mo：0.5％～2.0％、Ni：1.0％～2.8％、Mn：1.0％～3.5％、Si：0.1％～0.5％、N：0.1％～0.25％、P：≤0.03％、S：≤0.01％，余量为Fe及不可避免的杂质。A high corrosion resistant oil well pipe steel, characterized in that the components of the high corrosion resistant oil well pipe steel include, by mass percentage: C: ≤0.03%, Cr: 17.3%-18.4%, Mo: 0.5%-2.0%, Ni: 1.0%-2.8%, Mn: 1.0%-3.5%, Si: 0.1%-0.5%, N: 0.1%-0.25%, P: ≤0.03%, S: ≤0.01%, and the balance is Fe and unavoidable impurities.
  2. 根据权利要求1所述的高耐蚀油井管钢，其特征在于，所述高耐蚀油井管钢的组分中，Cr+3.3Mo+16N≥26。The high corrosion resistant oil well pipe steel according to claim 1 is characterized in that, in the composition of the high corrosion resistant oil well pipe steel, Cr+3.3Mo+16N≥26.
  3. 根据权利要求1所述的高耐蚀油井管钢，其特征在于，所述高耐蚀油井管钢的组分中，60Ni+17Mn-12Mo-800N≤0。The high corrosion resistant oil well pipe steel according to claim 1 is characterized in that, among the components of the high corrosion resistant oil well pipe steel, 60Ni+17Mn-12Mo-800N≤0.
  4. 根据权利要求1所述的高耐蚀油井管钢，其特征在于，所述高耐蚀油井管钢的组分以质量百分比计可以为：C：0.01％～0.03％、Cr：17.4％～18.4％、Mo：1.0％～2.0％、Ni：1.0％～2.7％、Mn：1.4％～3.2％、Si：0.1％～0.5％、N：0.13％～0.25％、P：≤0.03％、S：≤0.01％，余量为Fe及不可避免的杂质。The high corrosion resistant oil well pipe steel according to claim 1 is characterized in that the components of the high corrosion resistant oil well pipe steel, in terms of mass percentage, are: C: 0.01% to 0.03%, Cr: 17.4% to 18.4%, Mo: 1.0% to 2.0%, Ni: 1.0% to 2.7%, Mn: 1.4% to 3.2%, Si: 0.1% to 0.5%, N: 0.13% to 0.25%, P: ≤0.03%, S: ≤0.01%, and the balance is Fe and unavoidable impurities.
  5. 根据权利要求1所述的高耐蚀油井管钢，其特征在于，所述高耐蚀油井管钢的微观组织为铁素体+奥氏体+马氏体的混合组织。The high corrosion resistant oil well pipe steel according to claim 1 is characterized in that the microstructure of the high corrosion resistant oil well pipe steel is a mixed structure of ferrite + austenite + martensite.
  6. 根据权利要求5所述的高耐蚀油井管钢，其特征在于，所述高耐蚀油井管钢的微观组织中，奥氏体的体积百分含量为20％～40％，马氏体的体积百分含量为10％～40％。The high corrosion resistant oil well pipe steel according to claim 5 is characterized in that, in the microstructure of the high corrosion resistant oil well pipe steel, the volume percentage of austenite is 20% to 40%, and the volume percentage of martensite is 10% to 40%.
  7. 根据权利要求5所述的高耐蚀油井管钢，其特征在于，所述高耐蚀油井管钢的微观组织中，奥氏体晶粒尺寸＜3μm。The high corrosion resistant oil well pipe steel according to claim 5 is characterized in that, in the microstructure of the high corrosion resistant oil well pipe steel, the austenite grain size is less than 3 μm.
  8. 一种高耐蚀油井管钢的制备方法，其特征在于，用于制备权利要求1-7任一项所述的高耐蚀油井管钢，包括：A method for preparing a highly corrosion-resistant oil well pipe steel, characterized in that it is used to prepare the highly corrosion-resistant oil well pipe steel according to any one of claims 1 to 7, comprising:
    步骤1：将金属原材料熔炼成钢水；Step 1: Melting metal raw materials into molten steel;
    步骤2：采用连铸或模铸的方法将钢水冶炼成连铸坯或铸锭； Step 2: smelting the molten steel into continuous casting billets or ingots by continuous casting or mold casting;
    步骤3：将连铸坯或铸锭锻造开坯，制成锻坯；Step 3: Forging the continuous casting billet or ingot into a forging billet;
    步骤4：将锻坯轧制成管坯，通过控制热轧与冷却工艺参数得到高耐蚀油井管钢。Step 4: Roll the forged billet into a tube billet, and obtain high corrosion-resistant oil well pipe steel by controlling hot rolling and cooling process parameters.
  9. 根据权利要求8所述的制备方法，其特征在于，所述步骤3中，锻造开坯温度为1150～1250℃。The preparation method according to claim 8 is characterized in that in step 3, the forging temperature is 1150-1250°C.
  10. 根据权利要求7-9任一项所述的制备方法，其特征在于，所述步骤4中，控制热轧与冷却工艺参数包括：控制开轧温度1050℃以上，终轧温度950℃以上，轧制首道次变形量不大于30％，轧制终道次变形量不大于50％。 The preparation method according to any one of claims 7 to 9 is characterized in that, in step 4, controlling the hot rolling and cooling process parameters includes: controlling the starting rolling temperature to be above 1050°C, the final rolling temperature to be above 950°C, the deformation in the first rolling pass to be no more than 30%, and the deformation in the final rolling pass to be no more than 50%.
PCT/CN2023/137477 2022-12-13 2023-12-08 Highly corrosion-resistant oil well steel pipe and preparation method therefor WO2024125407A1 (en)

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