CN116287964A - Super duplex stainless steel with PREN (pre-treated steel) not less than 42 and preparation method of seamless tube - Google Patents
Super duplex stainless steel with PREN (pre-treated steel) not less than 42 and preparation method of seamless tube Download PDFInfo
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- 229910001039 duplex stainless steel Inorganic materials 0.000 title claims abstract description 90
- 238000002360 preparation method Methods 0.000 title claims abstract description 14
- 229910000831 Steel Inorganic materials 0.000 title claims description 41
- 239000010959 steel Substances 0.000 title claims description 41
- 238000005242 forging Methods 0.000 claims abstract description 65
- 238000000034 method Methods 0.000 claims abstract description 48
- 238000010438 heat treatment Methods 0.000 claims abstract description 47
- 238000003723 Smelting Methods 0.000 claims abstract description 28
- 238000005097 cold rolling Methods 0.000 claims abstract description 24
- 230000007797 corrosion Effects 0.000 claims abstract description 22
- 238000005260 corrosion Methods 0.000 claims abstract description 22
- 238000001125 extrusion Methods 0.000 claims abstract description 6
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 claims description 30
- 239000000243 solution Substances 0.000 claims description 24
- 229910052757 nitrogen Inorganic materials 0.000 claims description 21
- 239000002994 raw material Substances 0.000 claims description 20
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 claims description 18
- 238000004519 manufacturing process Methods 0.000 claims description 17
- 238000001556 precipitation Methods 0.000 claims description 17
- 238000004321 preservation Methods 0.000 claims description 14
- 238000001816 cooling Methods 0.000 claims description 12
- 238000005520 cutting process Methods 0.000 claims description 11
- 229910052698 phosphorus Inorganic materials 0.000 claims description 11
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 11
- 229910052786 argon Inorganic materials 0.000 claims description 9
- 229910052796 boron Inorganic materials 0.000 claims description 8
- 239000012535 impurity Substances 0.000 claims description 8
- 229910052759 nickel Inorganic materials 0.000 claims description 8
- 229910018072 Al 2 O 3 Inorganic materials 0.000 claims description 7
- 238000000137 annealing Methods 0.000 claims description 7
- 238000005266 casting Methods 0.000 claims description 7
- 229910052802 copper Inorganic materials 0.000 claims description 7
- 238000005554 pickling Methods 0.000 claims description 7
- 238000005238 degreasing Methods 0.000 claims description 6
- 229910052748 manganese Inorganic materials 0.000 claims description 6
- 238000002844 melting Methods 0.000 claims description 6
- 230000008018 melting Effects 0.000 claims description 6
- 238000012545 processing Methods 0.000 claims description 6
- 229910052750 molybdenum Inorganic materials 0.000 claims description 5
- 239000006104 solid solution Substances 0.000 claims description 5
- 229910052782 aluminium Inorganic materials 0.000 claims description 4
- 239000000203 mixture Substances 0.000 claims description 4
- 238000010079 rubber tapping Methods 0.000 claims description 3
- 238000003756 stirring Methods 0.000 claims description 3
- 238000005496 tempering Methods 0.000 claims 1
- 229910045601 alloy Inorganic materials 0.000 abstract description 10
- 239000000956 alloy Substances 0.000 abstract description 10
- PXHVJJICTQNCMI-UHFFFAOYSA-N nickel Substances [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 description 15
- 239000000047 product Substances 0.000 description 12
- 230000007547 defect Effects 0.000 description 10
- 229910000859 α-Fe Inorganic materials 0.000 description 7
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 6
- 229910052799 carbon Inorganic materials 0.000 description 6
- 239000010949 copper Substances 0.000 description 6
- 238000007689 inspection Methods 0.000 description 6
- 239000011572 manganese Substances 0.000 description 6
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 description 6
- 238000005498 polishing Methods 0.000 description 6
- 229910001566 austenite Inorganic materials 0.000 description 5
- 239000011651 chromium Substances 0.000 description 5
- 238000000227 grinding Methods 0.000 description 5
- 229910004261 CaF 2 Inorganic materials 0.000 description 4
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 4
- OAICVXFJPJFONN-UHFFFAOYSA-N Phosphorus Chemical compound [P] OAICVXFJPJFONN-UHFFFAOYSA-N 0.000 description 4
- 239000013078 crystal Substances 0.000 description 4
- 238000001514 detection method Methods 0.000 description 4
- 239000011574 phosphorus Substances 0.000 description 4
- VYZAMTAEIAYCRO-UHFFFAOYSA-N Chromium Chemical compound [Cr] VYZAMTAEIAYCRO-UHFFFAOYSA-N 0.000 description 3
- PWHULOQIROXLJO-UHFFFAOYSA-N Manganese Chemical compound [Mn] PWHULOQIROXLJO-UHFFFAOYSA-N 0.000 description 3
- 230000015572 biosynthetic process Effects 0.000 description 3
- 229910052804 chromium Inorganic materials 0.000 description 3
- 238000013461 design Methods 0.000 description 3
- 238000005553 drilling Methods 0.000 description 3
- 239000000463 material Substances 0.000 description 3
- 239000003345 natural gas Substances 0.000 description 3
- 230000000149 penetrating effect Effects 0.000 description 3
- ZOXJGFHDIHLPTG-UHFFFAOYSA-N Boron Chemical compound [B] ZOXJGFHDIHLPTG-UHFFFAOYSA-N 0.000 description 2
- ZOKXTWBITQBERF-UHFFFAOYSA-N Molybdenum Chemical compound [Mo] ZOKXTWBITQBERF-UHFFFAOYSA-N 0.000 description 2
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 2
- GWEVSGVZZGPLCZ-UHFFFAOYSA-N Titan oxide Chemical compound O=[Ti]=O GWEVSGVZZGPLCZ-UHFFFAOYSA-N 0.000 description 2
- 239000002253 acid Substances 0.000 description 2
- 238000011161 development Methods 0.000 description 2
- 239000012467 final product Substances 0.000 description 2
- 238000010304 firing Methods 0.000 description 2
- 230000005764 inhibitory process Effects 0.000 description 2
- 229910000765 intermetallic Inorganic materials 0.000 description 2
- 239000011733 molybdenum Substances 0.000 description 2
- 239000003921 oil Substances 0.000 description 2
- 239000011148 porous material Substances 0.000 description 2
- 239000000843 powder Substances 0.000 description 2
- 229910052710 silicon Inorganic materials 0.000 description 2
- 239000010703 silicon Substances 0.000 description 2
- 230000000087 stabilizing effect Effects 0.000 description 2
- 229910001220 stainless steel Inorganic materials 0.000 description 2
- 239000010935 stainless steel Substances 0.000 description 2
- 239000000126 substance Substances 0.000 description 2
- VEXZGXHMUGYJMC-UHFFFAOYSA-M Chloride anion Chemical compound [Cl-] VEXZGXHMUGYJMC-UHFFFAOYSA-M 0.000 description 1
- 235000008733 Citrus aurantifolia Nutrition 0.000 description 1
- FYYHWMGAXLPEAU-UHFFFAOYSA-N Magnesium Chemical compound [Mg] FYYHWMGAXLPEAU-UHFFFAOYSA-N 0.000 description 1
- 229910004298 SiO 2 Inorganic materials 0.000 description 1
- 241001062472 Stokellia anisodon Species 0.000 description 1
- 235000011941 Tilia x europaea Nutrition 0.000 description 1
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000005540 biological transmission Effects 0.000 description 1
- WUKWITHWXAAZEY-UHFFFAOYSA-L calcium difluoride Chemical compound [F-].[F-].[Ca+2] WUKWITHWXAAZEY-UHFFFAOYSA-L 0.000 description 1
- 238000004140 cleaning Methods 0.000 description 1
- 238000005336 cracking Methods 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- 230000001627 detrimental effect Effects 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 239000010436 fluorite Substances 0.000 description 1
- 239000007789 gas Substances 0.000 description 1
- 238000003306 harvesting Methods 0.000 description 1
- 239000000383 hazardous chemical Substances 0.000 description 1
- 239000004571 lime Substances 0.000 description 1
- 239000011159 matrix material Substances 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- TWNQGVIAIRXVLR-UHFFFAOYSA-N oxo(oxoalumanyloxy)alumane Chemical compound O=[Al]O[Al]=O TWNQGVIAIRXVLR-UHFFFAOYSA-N 0.000 description 1
- 239000003208 petroleum Substances 0.000 description 1
- 239000003209 petroleum derivative Substances 0.000 description 1
- 238000007670 refining Methods 0.000 description 1
- 239000013535 sea water Substances 0.000 description 1
- 238000005204 segregation Methods 0.000 description 1
- 238000000926 separation method Methods 0.000 description 1
- 239000002893 slag Substances 0.000 description 1
- 238000007711 solidification Methods 0.000 description 1
- 230000008023 solidification Effects 0.000 description 1
- 238000005728 strengthening Methods 0.000 description 1
- 239000004408 titanium dioxide Substances 0.000 description 1
- 210000005239 tubule Anatomy 0.000 description 1
- 238000003466 welding Methods 0.000 description 1
Classifications
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- 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
- 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
- C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
- C22B9/00—General processes of refining or remelting of metals; Apparatus for electroslag or arc remelting of metals
- C22B9/16—Remelting metals
- C22B9/18—Electroslag remelting
-
- 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
- C22C38/04—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
- C22C38/06—Ferrous alloys, e.g. steel alloys containing aluminium
-
- 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
- C22C38/42—Ferrous alloys, e.g. steel alloys containing chromium with nickel with copper
-
- 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
-
- 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
- C22C38/54—Ferrous alloys, e.g. steel alloys containing chromium with nickel with boron
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- 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
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- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Mechanical Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Manufacturing & Machinery (AREA)
- Physics & Mathematics (AREA)
- Thermal Sciences (AREA)
- Crystallography & Structural Chemistry (AREA)
- Heat Treatment Of Steel (AREA)
Abstract
The invention discloses a preparation method of super duplex stainless steel with PREN not less than 42 and a seamless pipe, which are characterized in that the super duplex stainless steel with PREN not less than 42 and the seamless pipe with high strength and high corrosion resistance is finally obtained by optimizing alloy components and adopting the processes of electric furnace smelting, electroslag remelting, forging cogging, extrusion pipe making, solution heat treatment and cold rolling.
Description
Technical Field
The invention belongs to the field of duplex stainless steel, and particularly relates to super duplex stainless steel with PREN more than or equal to 42 and a preparation method of a seamless pipe.
Background
The petrochemical industry is rapidly developed at present, but the development of petrochemical industry areas in China is unbalanced, chemical industry clusters taking petroleum, natural gas and the like as basic raw materials are mostly distributed in the west, and sales places of output products and downstream deep processing enterprises are mostly concentrated in eastern coastal areas, so that more than 95% of chemical raw materials need to be transported; "product and sales separation" determines the tightness of transportation of "hazardous chemical streams", so that steel materials used for manufacturing dangerous goods transportation equipment must not only have high strength, but also resist various forms of corrosion, and also resist seawater corrosion, and currently, duplex stainless steel and super duplex stainless steel are widely adopted for manufacturing related transportation equipment. As the corrosion resistance of the super duplex stainless steel for the transportation equipment is continuously improved, pren=cr% +3.3mo% +16n% 40-41 super duplex stainless steel has failed to meet the requirements, the demand is put forward for the component design and manufacturing method of super duplex stainless steel with PREN more than or equal to 42; this is also a pursuit in the drilling, harvesting and other industries of offshore oil and gas with equipment such as umbilical cables and transmission tubules.
Because the alloy content of super duplex stainless steel with PREN being more than or equal to 42 is higher than that of conventional super duplex stainless steel (PREN is in the range of 40-41), and the N content is also higher than that of conventional super duplex stainless steel, unexpected difficulties are caused to smelting and production. In order to solve the difficult problems and bottlenecks in smelting and production, the invention provides an electric furnace and electroslag to smelt/remelt PREN-42 super duplex stainless steel, and through alloy composition design, the invention avoids forging cogging and harmful phase precipitation in subsequent hot working.
At present, patents for the production of super duplex stainless steel products by adopting an electroslag remelting process are fewer. Chongqing material researchLiu Haiding et al (CN 201711374347.2) from Hospital Inc. invented an electroslag remelting system of super duplex stainless steel (UNS 32750, S32760, S32707, S32907, S33207, etc.) 2 :55-74％， CaO:5-20％，Al 2 O3:5-20％，MgO:5-15％，SiO 2 1-15%, so that the purity of the super duplex stainless steel is improved, harmful impurity elements are reduced, the electrode rod structure is optimized, the processing performance of the stainless steel is greatly improved, and the yield of hot processing is improved. Hu Huajun (CN 201310271485.3) of Jiangyin Hengshi forging Co., ltd.) proposes a forging method for super duplex stainless steel large-scale tube plate forgings, wherein a forging blank is produced by combining a plurality of small steel ingots with the weight of less than 10 tons and electroslag remelting into electroslag steel ingots with the diameter of 1750mm, but the patent does not specifically describe the electroslag condition. Du Xiaoliang (CN 201010281943.8) of Jiangsu New alloy practical Co., ltd.) in the production method of a super duplex stainless steel welding material, an electroslag remelting process is involved, and the ratio of electroslag is mainly: 25g of aluminum powder, 230g of aluminum oxide powder, 100g of lime, 100g of magnesium powder, 1240g of fluorite powder and 25g of titanium dioxide. The electroslag was applied at 42 volts and current 2200-2800A. Liao Yunhu et al (CN 201611105338.9) from Sichuan Liuhe forging Co., ltd.) utilize electroslag remelting refining to further reduce the content of impurity elements in the super duplex stainless steel, the steps and process parameters being that the slag system is CaF 2 ：Al 2 O 3 : caO: mgo=60:25:10:5; the power system is that the voltage is 56V plus or minus 2V and the current is 7500 plus or minus 300A.
Disclosure of Invention
Aiming at the defects in the prior art, the invention aims to provide the super duplex stainless steel with PREN more than or equal to 42 and the preparation method of the seamless pipe, which optimize alloy components from aspects of harmful phase inhibition, strength improvement and the like, ensure that an electroslag ingot does not have nitrogen pores by adopting the characteristics of an electroslag remelting process, ensure the smooth proceeding of a forging process, effectively reduce the surface grinding amount of a tube blank, improve the yield of a final product, prepare the super duplex stainless steel seamless pipe with excellent mechanical property and PREN more than or equal to 42, and meet the requirements of special industries such as dangerous goods transportation and treatment, drilling of offshore oil and natural gas and the like.
In order to achieve the above purpose, the invention adopts the following technical scheme:
the invention provides super duplex stainless steel with PREN not less than 42, which comprises the following components in percentage by weight: c:0.022 to 0.030 percent, si:0.10 to 0.80 percent of Mn:0.10 to 1.20 percent, less than or equal to 0.022 percent of P, less than or equal to 0.003 percent of S, less than or equal to 0.030 percent of Al, less than or equal to 0.50 percent of Cu and N: 0.265-0.295%, cr:25.7 to 26.0 percent of Ni:6.0 to 8.0 percent of Mo: 3.66-3.75%, B: 0.002-0.005%, and the balance of Ni and unavoidable impurities.
Preferably, the pitting corrosion resistance index PREN of the super duplex stainless steel with PREN being more than or equal to 42 meets the following conditions:
pren=cr+3.3×mo+16×n is not less than 42%; and/or
The critical temperature for precipitation of the harmful phase sigma phase of the super duplex stainless steel with PREN being more than or equal to 42 is as follows:
T σ ＝1000×(4.17-0.338×Cr+5.16×Mo) (1/11.2) 273 is less than or equal to 1000 ℃; and/or
The precipitation critical temperature of the harmful phase Cr2N phase of the super duplex stainless steel with PREN being more than or equal to 42 meets the following conditions:
T Cr2N ＝1000×(-61.1+40.4×C+1.97×Cr+2.49×Mo+59.6×N) (1/9.6) -273≤1080℃。
according to a second aspect of the invention, a super duplex stainless steel seamless pipe with PREN not less than 42 prepared from the super duplex stainless steel with PREN not less than 42 according to the first aspect of the invention is provided, wherein the room temperature tensile strength of the super duplex stainless steel seamless pipe with PREN not less than 42 is not less than 800MPa, the yield strength is not less than 650MPa, and the elongation is not less than 30%.
The third aspect of the invention provides a preparation method of a super duplex stainless steel seamless pipe with PREN being more than or equal to 42, which comprises the following steps:
s1, smelting, namely, proportioning raw materials of the super duplex stainless steel with PREN more than or equal to 42 according to the composition of claim 1, wherein the raw materials are smelted by an electric furnace and electroslag remelted to obtain electroslag ingots;
s2, forging and cogging, namely heating the electroslag ingot, and then forging and cogging to obtain a tube blank;
s3, extruding and manufacturing a tube, namely extruding and processing the tube blank, and obtaining a pierced billet after water cooling;
s4, solution heat treatment, namely performing solution heat treatment on the pierced billet, and then performing water cooling;
s5, cold rolling, namely cutting and pickling the pierced billet, and then performing multi-pass cold rolling to obtain the super duplex stainless steel seamless pipe with PREN more than or equal to 42.
Preferably, in the step S1:
in the electric furnace smelting process, nitrogen stirring is adopted, argon protection pouring is adopted during molten steel tapping, and the flow of the argon is 2-5 Nm 3 And/h, wherein the casting temperature is 1600-1650 ℃; and/or
In the electroslag remelting process, the electroslag system adopted comprises the following components: caF (CaF) 2 ：Al 2 O 3 : caO: mgO=65-75:15-22:3-7:3-7; and/or
In the electroslag remelting process, the steady-state melting speed of the electroslag is 6.0-7.0 kg/min.
Preferably, in the step S2:
in the heating treatment process, the heating temperature is 1220-1250 ℃, and the heat preservation time is (110-130 min) multiplied by the thickness of the electroslag ingot per 100mm; and/or
In the forging and cogging process, the forging temperature is not less than 1100 ℃, and the forging stopping temperature is not less than 1000 ℃; and/or
In the forging and cogging process, the temperature of the surface of the electroslag ingot is more than or equal to 1000 ℃ through furnace return heating.
Preferably, in the step S2, the temperature of the return furnace is 1220-1250 ℃ and the heat preservation time is 40-60 min in the forging and cogging process.
Preferably, in the step S3, the extrusion temperature is 1150-1200 ℃.
Preferably, in the step S4, in the solution heat treatment, the solution temperature is 1080-1150 ℃ and the treatment time is 20-40 min.
Preferably, in the step S5:
in the cold rolling process, degreasing, solid solution annealing heat treatment and straightening are carried out after each pass of cold rolling; and/or
The room-temperature tensile strength of the super duplex stainless steel seamless pipe with PREN not less than 42 is not less than 800MPa, the yield strength is not less than 650MPa, and the elongation is not less than 30%.
The principle of the composition design of the super duplex stainless steel with PREN more than or equal to 42 is as follows:
c: the strong austenite forms elements, plays a role in stabilizing an austenite structure, and the increase of the elements can improve the mechanical property of the steel, but when the content is too high, the elements can be combined with Cr elements in the steel to form M23C6 type carbide, so that the surrounding matrix is lean in chromium, and the intergranular corrosion resistance is reduced. The carbon content is limited to a range of 0.022 to 0.030wt% in the present invention.
Si: the ferrite forming element is a deoxidizer in the smelting process on one hand, and can be used as an element for adjusting the ferrite phase content on the other hand. Too high a silicon content promotes precipitation of intermetallic compounds in the duplex stainless steel, so that the performance is lowered. The silicon content in the present invention is limited to a range of 0.10 to 0.80 wt%.
Mn: austenite forming and stabilizing elements are also deoxidizers in the smelting process. In addition, it has a relatively strong affinity for nitrogen, and its addition significantly increases the nitrogen solubility of the steel. However, excessive manganese may reduce the acid corrosion resistance of the duplex stainless steel, resulting in accelerated corrosion. The manganese content in the present invention is limited to a range of 0.10 to 1.20 wt%.
Cr: ferrite phase forming elements are also the most important elements for enabling the duplex stainless steel to obtain corrosion resistance, and the pitting corrosion resistance and the intergranular corrosion resistance of the steel are obviously improved. It has strong affinity with nitrogen and is also an important element for improving the nitrogen solubility of the duplex stainless steel. Therefore, the ferrite content of the duplex stainless steel can be adjusted by adding the ferrite, and the corrosion resistance of the steel is improved. However, it is also a key element for the formation of Sigma phases and intermetallic compounds in steel, so that the chromium content in the present invention is limited to the range of 25.70 to 26.00 wt%.
Ni: austenite forms and stabilizes elements, improving the acid corrosion resistance of stainless steel. But its content needs to be controlled since it determines the cost and price of the steel grade. The nickel content in the present invention is limited to a range of 6.00-8.00%.
Mo: the ferrite forming element, together with nitrogen, can significantly improve the corrosion resistance of the steel and promote the corrosion resistance of chromium in the steel. Molybdenum is however also a key element in steel for sigma phase and intermetallic formation and is expensive, too high increasing the cost of the alloy. The molybdenum content in the present invention is limited to a range of 3.66 to 3.75 wt%.
B: as a high temperature grain boundary strengthening element, the thermoplasticity of steel at high temperature can be improved. However, excessive amounts tend to cause low-melting-point phases to be easily formed on grain boundaries in duplex stainless steel, so that high-temperature hot workability is deteriorated. The boron content in the present invention is limited to a range of 0.002 to 0.005 wt%.
N: is one of important elements of the duplex stainless steel, is a strong austenite forming element like carbon, and can replace the austenitizing effect of nickel together with manganese; the corrosion resistance and the crevice corrosion resistance of the duplex stainless steel in a chloride ion environment can be obviously improved by the synergy of the corrosion resistance and the crevice corrosion resistance of the duplex stainless steel. It also increases the strength of duplex stainless steel without decreasing toughness. However, when the nitrogen content is too high, the nitrogen is separated out from molten steel in a nitrogen hole mode during smelting, so that products are scrapped, the deformation resistance during hot working is improved, and the hot working is difficult. The nitrogen content in the present invention is limited to a range of 0.265 to 0.295 wt%.
P, S: p, S is a detrimental element of the alloy of the present invention, and an excessively high content deteriorates the hot workability of the alloy and easily causes micro segregation, and the lower the content is, the better the content, and the content is controlled to be within the range of P.ltoreq.0.022 wt% and S.ltoreq.0.003 wt% in consideration of the manufacturing cost of the alloy.
The preparation method of the super duplex stainless steel and the seamless pipe with PREN more than or equal to 42 has the beneficial effects that:
according to the preparation method of the super duplex stainless steel with PREN more than or equal to 42 and the seamless pipe, alloy components are optimized from aspects of harmful phase inhibition, strength improvement and the like, and the characteristics of an electroslag remelting process are adopted, so that nitrogen pores do not appear in an electroslag ingot, the smooth proceeding of a forging process is ensured, the surface grinding amount of a pipe blank is effectively reduced, the yield of a final product is improved, the super duplex stainless steel seamless pipe with excellent mechanical property and PREN more than or equal to 42 is prepared, and the requirements of special industries such as dangerous goods transportation and treatment, drilling of marine petroleum and natural gas and the like are met.
Detailed Description
In order to better understand the above technical solution of the present invention, the technical solution of the present invention is further described below with reference to examples.
The super duplex stainless steel with PREN not less than 42 provided by the invention comprises the following components in percentage by weight: c:0.022 to 0.030 percent, si:0.10 to 0.80 percent of Mn:0.10 to 1.20 percent, less than or equal to 0.022 percent of P, less than or equal to 0.003 percent of S, less than or equal to 0.030 percent of Al, less than or equal to 0.50 percent of Cu and N: 0.265-0.295%, cr:25.7 to 26.0 percent of Ni:6.0 to 8.0 percent of Mo: 3.66-3.75%, B: 0.002-0.005%, and the balance of Ni and unavoidable impurities.
The pitting corrosion resistance index PREN of the super duplex stainless steel with PREN being more than or equal to 42 meets the following conditions:
pren=cr+3.3×mo+16×n is not less than 42%; and/or
The critical temperature for precipitation of the harmful phase sigma phase of the super duplex stainless steel with PREN more than or equal to 42 is as follows:
T σ ＝1000×(4.17-0.338×Cr+5.16×Mo) (1/11.2) 273 is less than or equal to 1000 ℃; and/or
The precipitation critical temperature of the harmful phase Cr2N phase of the super duplex stainless steel with PREN more than or equal to 42 meets the following conditions:
T Cr2N ＝1000×(-61.1+40.4×C+1.97×Cr+2.49×Mo+59.6×N) (1/9.6) -273≤1080℃。
the super duplex stainless steel with PREN more than or equal to 42 can be manufactured into super duplex stainless steel seamless pipes with PREN more than or equal to 42, the room temperature tensile strength more than or equal to 800MPa, the yield strength more than or equal to 650MPa, and the elongation more than or equal to 30%.
The preparation method of the super duplex stainless steel seamless pipe with PREN more than or equal to 42 comprises the following process flows: electric furnace smelting, electroslag remelting, forging cogging, extruding to prepare a pipe, solution heat treatment and cold rolling, and specifically comprises the following steps of:
s1, smelting, namely proportioning raw materials according to the components of the super duplex stainless steel with PREN more than or equal to 42, wherein the raw materials are smelted by an electric furnace and electroslag remelted to obtain an electroslag ingot;
the specific process is as follows: firstly, proportioning raw materials according to the components of super duplex stainless steel with PREN more than or equal to 42, wherein the raw materials adopt clean scrap steel with low phosphorus and low copper, and the like; smelting the proportioned raw materials into an electrode rod by using an electric furnace smelting with the volume of more than or equal to 6 tons, wherein nitrogen stirring is adopted in the electric furnace smelting process, argon protection casting is adopted during molten steel tapping, and the argon flow is controlled to be 2-5 Nm 3 And/h, wherein the casting temperature is 1600-1650 ℃; and then electroslag remelting smelting is carried out to obtain an electroslag ingot, and the purity in steel is improved on one hand, and the formation of nitrogen holes in the electroslag ingot is reduced on the other hand through an electroslag remelting process with relatively high cooling speed during solidification, wherein the electroslag system adopted in the electroslag remelting process comprises the following components: caF (CaF) 2 ：Al 2 O 3 : caO: mgO=65-75:15-22:3-7:3-7, and the steady-state melting speed of the electroslag is 6.0-7.0 kg/min.
S2, forging and cogging, namely heating the electroslag ingot, and then forging and cogging to obtain a tube blank;
the specific process is as follows: the electroslag ingot is heated, excessive ferrite appears when the heating temperature is too high or the heat preservation time is too long, so that the advantage of the super duplex stainless steel on the steel performance is lost, and the phase appears high Wen, therefore, the heating temperature is controlled to 1220-1250 ℃, the upper limit is controlled as much as possible, and the temperature of the surface of the electroslag ingot is preferably up to 1250 ℃, the surface temperature of the electroslag ingot before forging is uniform, and the heat preservation time is 110-130min/100mm (thickness of the electroslag ingot), namely, the heat preservation time is (110-130 min) multiplied by the thickness of the electroslag ingot mm/100mm; then the forging and cogging are carried out,
because the steel has poor cast state thermoplasticity, the first firing adopts a light hammer to strike quickly, the deformation is controlled to be less than or equal to 5 percent, the purpose of breaking the cast state structure is to increase the deformation properly after the firing, the uniform deformation is needed to prevent surface cracks in the forging process, and the surface temperature of the electroslag ingot in the forging and cogging process is more than or equal to the critical temperature T of the sigma phase precipitation of the harmful phase σ (T σ ＝1000×(4.17-0.338×Cr+5.16×Mo) (1/11.2) -273≤1000℃) The surface temperature of the electroslag ingot in the forging and cogging process is more than or equal to 1000 ℃, when the surface temperature of the electroslag ingot is close to 1000 ℃, the furnace returning heating is immediately carried out to avoid the precipitation of harmful phase sigma, the furnace returning heating temperature is controlled to be 1220-1250 ℃, the heat preservation time is controlled to be 40-60 min, surface defects are cleaned during forging and after forging, the cracking of tip cracks along crystal development is prevented, particularly, the surface defects of a plurality of slender cracks which are consistent with the striking direction (and vertical to the deformation direction) are immediately subjected to the forging cleaning, and the surface defects are immediately polished or directly polished after carbon planing. Wherein in the forging and cogging process, the forging temperature is not less than 1100 ℃, the forging stopping temperature is not less than 1000 ℃,
s3, extruding and manufacturing a tube, namely extruding and processing the tube blank, and obtaining a pierced billet after water cooling;
the specific process is as follows: turning and cutting a tube blank obtained in the forging and cogging process into a steel bar with the conventional size of phi 236+/-5 mm multiplied by 450-800 m, then extruding the steel bar, controlling the extrusion temperature to 1150-1200 ℃, and performing water cooling after extrusion to obtain a pierced billet with the diameter of phi 114+/-5 mm multiplied by 12+/-0.5 mm;
s4, solution heat treatment, namely performing solution heat treatment on the pierced billet, and then performing water cooling;
the specific process is as follows: the pierced billet is subjected to solution heat treatment, and the precipitation of Cr2N phase of the harmful phase is prevented in the process, so that the solution heat treatment temperature is more than or equal to the critical precipitation temperature T of Cr2N phase of the harmful phase Cr2N (T Cr2N ＝1000×(-61.1+40.4×C+1.97×Cr+2.49×Mo+59.6×N) (1/9.6) 273 ℃ below zero is less than or equal to 1080 ℃, so that the solution heat treatment is controlled to be 1080-1150 ℃ and the treatment time is controlled to be 20-40 min, and then water cooling is performed.
S5, cold rolling, namely cutting and pickling the pierced billet, and then performing multi-pass cold rolling to obtain the super duplex stainless steel seamless pipe with PREN more than or equal to 42.
The specific process is as follows: cutting and pickling the pierced billet, and then carrying out multi-pass cold rolling according to the size of the pierced billet and the size of a final finished product to obtain a boron-containing super duplex stainless steel seamless pipe, such as 4-5 times of cold rolling; the degreasing treatment, the solution annealing heat treatment and the straightening are required to be carried out after each cold rolling pass, wherein the treatment temperature is 1080-1150 ℃ and the treatment time is 20-40 min during the solution annealing heat treatment.
The finished product performance detection shows that the room temperature tensile strength of the super duplex stainless steel seamless pipe with PREN more than or equal to 42 is more than or equal to 800MPa, the yield strength is more than or equal to 650MPa, and the elongation is more than or equal to 30%.
The super duplex stainless steel, seamless pipe and preparation method of PREN not less than 42 of the present invention are further described below with reference to specific examples.
Example 1
1) Electric furnace smelting
Smelting by adopting a 40-ton electric furnace, and smelting the electrode rod with the following components (weight percentage) according to the components of the super duplex stainless steel with PREN more than or equal to 42 as raw materials:
c:0.025%, si:0.50%, mn:0.60%, P:0.018%, S:0.003%, al:0.012%, cu:0.30%, N:0.28%, cr:25.85%, ni:7.0%, mo:3.705%, B:0.003%, the balance being nickel and unavoidable impurities.
The raw materials adopt the following principle: clean scrap steel with low phosphorus and low copper and the like are used as raw materials; argon protection pouring is adopted in electric furnace smelting, and the pouring temperature is 1630 ℃. Casting into an electrode rod with the diameter of 422 mm.
2) Electroslag remelting
The electroslag system adopted is CaF 2 :Al 2 O 3 CaO, mgO=70:16:7:7, the steady-state melting speed of the electroslag is controlled to be 6.0-7.0 kg/min, and the capping time is 40 minutes.
3) Forging cogging
Heating temperature and holding time are selected: heating temperature is selected to 1240 ℃; the temperature of the open forging electroslag ingot is uniform. The heat preservation time is 120min/100mm (thickness of electroslag ingot), namely, the heat preservation time is 120min multiplied by the thickness of the electroslag ingot to be mm/100mm;
forging: forging temperature: 1110 ℃, stop forging temperature: 1000 ℃. In the forging and cogging process, the heating temperature of the return furnace (return chamber furnace) is 1220 ℃, and the temperature is kept for 60 minutes.
Surface defects are cleaned during and after forging, so that cracks of tip cracks are prevented from developing along crystals, and particularly, the surface defects of a plurality of slender cracks which are consistent with the striking direction (and vertical to the deformation direction) are required to be immediately cleaned by stopping forging, and polishing or direct polishing is performed immediately after carbon planing.
4) Extruded tube
Preparation:
turning and cutting the tube blank after hot forging into a steel rod with the conventional size of phi 236mm multiplied by 750mm, and carrying out surface dye inspection to display forging cracks on the surface of the steel rod; then adopting a surface grinding method to remove micro cracks on the surface of the steel bar, otherwise, the smooth running and quality of the penetrating pipe are affected;
extruding a pipe:
and (3) extruding the steel bar at 1180 ℃ to obtain the finished pierced billet with the size phi of 114 multiplied by 12mm.
3) Solution heat treatment
Carrying out solution heat treatment on the pierced billet: water cooling at 1080 deg.c for 30 min.
4) Cold rolling
Cutting and pickling the pierced billet; then carrying out multi-pass cold rolling according to the size of the pierced billet and the size of a final finished product, and carrying out degreasing, solid solution annealing heat treatment (1080 ℃ for 40 min) and straightening after each pass of cold rolling; the final size of the finished product is phi 38 multiplied by 4mm.
The super duplex stainless steel seamless pipe with PREN not less than 42 is subjected to performance detection and tissue inspection, and the results are shown in tables 1 and 2.
Example 2
1) Electric furnace smelting
Smelting by adopting a 40-ton electric furnace, and smelting the electrode rod with the following components (weight percentage) according to the components of the super duplex stainless steel with PREN more than or equal to 42 as raw materials:
c:0.030%, si:0.80%, mn:1.20%, P:0.016%, S:0.003%, al:0.012%, cu:0.50%, N:0.295%, cr:26.0%, ni:8.0%, mo:3.75%, B:0.005% of nickel and the balance of unavoidable impurities.
The raw materials adopt the following principle: clean scrap steel with low phosphorus and low copper and the like are used as raw materials; argon protection pouring is adopted in electric furnace smelting, and the pouring temperature is 1610 ℃. Casting into an electrode rod with the diameter of 422 mm.
2) Electroslag remelting
The electroslag system adopted is CaF 2 :Al 2 O 3 CaO, mgO=73:17:5:5, electroslag steady-state voltage 58-62V, current 10000-11500A, electroslag steady-state melting speed 6.0-7.0 kg/min, capping time 43 minutes.
3) Forging cogging
Heating temperature and holding time are selected: the heating temperature is selected to be 1230 ℃; the temperature of the open forging electroslag ingot is uniform. The heat preservation time is 120min/100mm (thickness of electroslag ingot), namely, the heat preservation time is 120min multiplied by the thickness of the electroslag ingot to be mm/100mm;
forging: forging temperature: 1130 ℃, stop forging temperature: 1040 ℃. In the forging cogging process, the temperature is heated to 1240 ℃ by a furnace returning (a furnace returning chamber), and the temperature is kept for 60 minutes.
Surface defects are cleaned during and after forging, so that cracks of tip cracks are prevented from developing along crystals, and particularly, the surface defects of a plurality of slender cracks which are consistent with the striking direction (and vertical to the deformation direction) are required to be immediately cleaned by stopping forging, and polishing or direct polishing is performed immediately after carbon planing.
4) Extruded tube
Preparation:
turning and cutting the tube blank after hot forging into a steel rod with the conventional size of phi 236mm multiplied by 800mm, and carrying out surface dye inspection to display forging cracks on the surface of the steel rod; then adopting a surface grinding method to remove micro cracks on the surface of the steel bar, otherwise, the smooth running and quality of the penetrating pipe are affected;
extruding a pipe:
and (3) extruding the steel bar at 1180 ℃ to obtain the finished pierced billet with the size phi of 114 multiplied by 12mm.
3) Solution heat treatment
Carrying out solution heat treatment on the pierced billet: water cooling at 1080 deg.c for 30 min.
4) Cold rolling
Cutting and pickling the pierced billet; then carrying out multi-pass cold rolling according to the size of the pierced billet and the size of the final finished product, and carrying out degreasing, solid solution annealing heat treatment (1150 ℃ multiplied by 20 min) and straightening after each pass of cold rolling; the final size of the finished product is phi 57 multiplied by 5.7mm.
The super duplex stainless steel seamless pipe with PREN not less than 42 is subjected to performance detection and tissue inspection, and the results are shown in tables 1 and 2.
Example 3
1) Electric furnace smelting
Smelting by adopting a 40-ton electric furnace, and smelting the electrode rod with the following components (weight percentage) according to the components of the super duplex stainless steel with PREN more than or equal to 42 as raw materials:
c:0.022%, si:0.10%, mn:0.10%, P:0.020%, S:0.002%, al:0.013%, cu:0.10%, N:0.265%, cr:25.7%, ni:6.0%, mo:3.66%, B:0.002%, the balance being nickel and unavoidable impurities.
The raw materials adopt the following principle: clean scrap steel with low phosphorus and low copper and the like are used as raw materials; argon protection pouring is adopted in electric furnace smelting, and the pouring temperature is 1630 ℃. Casting into an electrode rod with the diameter of 422 mm.
2) Electroslag remelting
The electroslag system adopted is CaF 2 :Al 2 O 3 CaO, mgO=70:18:6:6, electroslag steady-state voltage 58-62V, current 10000-11500A, electroslag steady-state melting speed 6.0-7.0 kg/min, capping time 42 minutes.
3) Forging cogging
Heating temperature and holding time are selected: heating temperature is selected to 1240 ℃; the temperature of the open forging electroslag ingot is uniform. The heat preservation time is 120min/100mm (thickness of electroslag ingot), namely, the heat preservation time is 120min multiplied by the thickness of the electroslag ingot to be mm/100mm;
forging: forging temperature: 1130 ℃, stop forging temperature: 1020 ℃. In the forging and cogging process, the heating temperature of the return furnace (return chamber furnace) is 1220 ℃, and the temperature is kept for 60 minutes.
Surface defects are cleaned during and after forging, so that cracks of tip cracks are prevented from developing along crystals, and particularly, the surface defects of a plurality of slender cracks which are consistent with the striking direction (and vertical to the deformation direction) are required to be immediately cleaned by stopping forging, and polishing or direct polishing is performed immediately after carbon planing.
4) Extruded tube
Preparation:
turning and cutting the tube blank after hot forging into a steel rod with the conventional size of phi 236mm multiplied by 700mm, and carrying out surface dye inspection to display forging cracks on the surface of the steel rod; then adopting a surface grinding method to remove micro cracks on the surface of the steel bar, otherwise, the smooth running and quality of the penetrating pipe are affected;
extruding a pipe:
and (3) extruding the steel bar at 1180 ℃ to obtain the finished pierced billet with the size phi of 114 multiplied by 12mm.
3) Solution heat treatment
Carrying out solution heat treatment on the pierced billet: water cooling at 1080 deg.c for 30 min.
4) Cold rolling
Cutting and pickling the pierced billet; then carrying out multi-pass cold rolling according to the size of the pierced billet and the size of a final finished product, and carrying out degreasing, solid solution annealing heat treatment (1100 ℃ for 30 min) and straightening after each pass of cold rolling; the final size of the finished product is phi 38 multiplied by 4mm.
The super duplex stainless steel seamless pipe with PREN not less than 42 is subjected to performance detection and tissue inspection, and the results are shown in tables 1 and 2.
TABLE 1 mechanical Properties of super duplex stainless Steel seamless tubes with PREN being greater than or equal to 42
TABLE 2 nonmetallic inclusion level of super duplex stainless steel seamless tubes with PREN > 42
As can be seen from the combination of Table 1, the super duplex stainless steel seamless pipe with PREN not less than 42 has room temperature tensile strength of 800MPa, yield strength not less than 650MPa, elongation not less than 30%, pitting corrosion resistance index PREN not less than 42, and precipitation critical temperature of harmful phase sigma phase meeting: t (T) σ The critical temperature of precipitation of the harmful phase Cr2N is less than or equal to 1000 ℃, and the critical temperature of precipitation of the harmful phase Cr2N is as follows: t (T) Cr2N The precipitation critical temperature of the harmful phase M23C6 is less than or equal to 1080 ℃, and the precipitation critical temperature of the harmful phase M23C6 meets the following conditions: t (T) M23C6 Not less than 880 ℃. As can be seen from Table 2, the super duplex stainless steel seamless tube with PREN not less than 42 according to the inventionFewer nonmetallic inclusions.
It will be appreciated by persons skilled in the art that the above embodiments are provided for illustration only and not for limitation of the invention, and that variations and modifications of the above described embodiments are intended to fall within the scope of the claims of the invention as long as they fall within the true spirit of the invention.
Claims (10)
1. The super duplex stainless steel with PREN not less than 42 is characterized by comprising the following components in percentage by weight: c:0.022 to 0.030 percent, si:0.10 to 0.80 percent of Mn:0.10 to 1.20 percent, less than or equal to 0.022 percent of P, less than or equal to 0.003 percent of S, less than or equal to 0.030 percent of Al, less than or equal to 0.50 percent of Cu and N: 0.265-0.295%, cr:25.7 to 26.0 percent of Ni:6.0 to 8.0 percent of Mo: 3.66-3.75%, B: 0.002-0.005%, and the balance of Ni and unavoidable impurities.
2. The super duplex stainless steel having PREN not less than 42 as claimed in claim 1,
the pitting corrosion resistance index PREN of the super duplex stainless steel with PREN being more than or equal to 42 meets the following conditions:
pren=cr+3.3×mo+16×n is not less than 42%; and/or
The critical temperature for precipitation of the harmful phase sigma phase of the super duplex stainless steel with PREN being more than or equal to 42 is as follows:
T σ ＝1000×(4.17-0.338×Cr+5.16×Mo) (1/11.2) 273 is less than or equal to 1000 ℃; and/or
The precipitation critical temperature of the harmful phase Cr2N phase of the super duplex stainless steel with PREN being more than or equal to 42 meets the following conditions:
T Cr2N ＝1000×(-61.1+40.4×C+1.97×Cr+2.49×Mo+59.6×N) (1/9.6) -273≤1080℃。
3. a super duplex stainless steel seamless pipe with PREN not less than 42 prepared based on the super duplex stainless steel with PREN not less than 42 according to claim 1 or 2, wherein the room temperature tensile strength of the super duplex stainless steel seamless pipe with PREN not less than 42 is not less than 800MPa, the yield strength is not less than 650MPa, and the elongation is not less than 30%.
4. The preparation method of the super duplex stainless steel seamless pipe with PREN being more than or equal to 42 is characterized by comprising the following steps of:
s1, smelting, namely, proportioning raw materials of the super duplex stainless steel with PREN more than or equal to 42 according to the composition of claim 1, wherein the raw materials are smelted by an electric furnace and electroslag remelted to obtain electroslag ingots;
s2, forging and cogging, namely heating the electroslag ingot, and then forging and cogging to obtain a tube blank;
s3, extruding and manufacturing a tube, namely extruding and processing the tube blank, and obtaining a pierced billet after water cooling;
s4, solution heat treatment, namely performing solution heat treatment on the pierced billet, and then performing water cooling;
s5, cold rolling, namely cutting and pickling the pierced billet, and then performing multi-pass cold rolling to obtain the super duplex stainless steel seamless pipe with PREN more than or equal to 42.
5. The method for producing super duplex stainless steel seamless tube according to claim 4, wherein in step S1:
in the electric furnace smelting process, nitrogen stirring is adopted, argon protection pouring is adopted during molten steel tapping, and the flow of the argon is 2-5 Nm 3 And/h, wherein the casting temperature is 1600-1650 ℃; and/or
In the electroslag remelting process, the electroslag system adopted comprises the following components: caF (CaF) 2 ：Al 2 O 3 : caO: mgO=65-75:15-22:3-7:3-7; and/or
In the electroslag remelting process, the steady-state melting speed of the electroslag is 6.0-7.0 kg/min.
6. The method for producing super duplex stainless steel seamless tube according to claim 5, wherein in step S2:
in the heating treatment process, the heating temperature is 1220-1250 ℃, and the heat preservation time is (110-130 min) multiplied by the thickness of the electroslag ingot per 100mm; and/or
In the forging and cogging process, the forging temperature is not less than 1100 ℃, and the forging stopping temperature is not less than 1000 ℃; and/or
In the forging and cogging process, the temperature of the surface of the electroslag ingot is more than or equal to 1000 ℃ through furnace return heating.
7. The method for producing super duplex stainless steel seamless pipe according to claim 6, wherein in step S2, the temperature of the tempering furnace is 1220-1250 ℃ and the heat preservation time is 40-60 min.
8. The process for producing a super duplex stainless steel seamless tube having a PREN > 42 according to claim 4, wherein in step S3, the extrusion temperature is 1150-1200deg.C during the extrusion tube production process.
9. The method for producing a super duplex stainless steel seamless tube having a PREN of 42 or more according to claim 4, wherein in the step S4, the solution temperature is 1080 to 1150 ℃ and the treatment time is 20 to 40 minutes in the solution heat treatment.
10. The method for producing super duplex stainless steel seamless tube according to claim 4, wherein in step S5:
in the cold rolling process, degreasing, solid solution annealing heat treatment and straightening are carried out after each pass of cold rolling; and/or
The room-temperature tensile strength of the super duplex stainless steel seamless pipe with PREN not less than 42 is not less than 800MPa, the yield strength is not less than 650MPa, and the elongation is not less than 30%.
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