CN113088812A - High-strength-toughness ultralow-temperature impact-resistant tubing head forging blank and manufacturing method thereof - Google Patents
High-strength-toughness ultralow-temperature impact-resistant tubing head forging blank and manufacturing method thereof Download PDFInfo
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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
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21J—FORGING; HAMMERING; PRESSING METAL; RIVETING; FORGE FURNACES
- B21J5/00—Methods for forging, hammering, or pressing; Special equipment or accessories therefor
- B21J5/002—Hybrid process, e.g. forging following casting
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21J—FORGING; HAMMERING; PRESSING METAL; RIVETING; FORGE FURNACES
- B21J5/00—Methods for forging, hammering, or pressing; Special equipment or accessories therefor
- B21J5/06—Methods for forging, hammering, or pressing; Special equipment or accessories therefor for performing particular operations
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21J—FORGING; HAMMERING; PRESSING METAL; RIVETING; FORGE FURNACES
- B21J5/00—Methods for forging, hammering, or pressing; Special equipment or accessories therefor
- B21J5/06—Methods for forging, hammering, or pressing; Special equipment or accessories therefor for performing particular operations
- B21J5/08—Upsetting
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- 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
- C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
- C21D1/18—Hardening; Quenching with or without subsequent tempering
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
- C21D1/26—Methods of annealing
- C21D1/28—Normalising
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D6/00—Heat treatment of ferrous alloys
- C21D6/004—Heat treatment of ferrous alloys containing Cr and Ni
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D6/00—Heat treatment of ferrous alloys
- C21D6/005—Heat treatment of ferrous alloys containing Mn
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- 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
- C21D6/00—Heat treatment of ferrous alloys
- C21D6/008—Heat treatment of ferrous alloys containing Si
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- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D9/00—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
- C21D9/0068—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for particular articles not mentioned below
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- C22C33/04—Making ferrous alloys by melting
- C22C33/06—Making ferrous alloys by melting using master alloys
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- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/001—Ferrous alloys, e.g. steel alloys containing N
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- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/002—Ferrous alloys, e.g. steel alloys containing In, Mg, or other elements not provided for in one single group C22C38/001 - C22C38/60
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- C22C38/008—Ferrous alloys, e.g. steel alloys containing tin
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- C22C38/04—Ferrous alloys, e.g. steel alloys containing manganese
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- C22C38/06—Ferrous alloys, e.g. steel alloys containing aluminium
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- 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
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- 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
- C22C38/46—Ferrous alloys, e.g. steel alloys containing chromium with nickel with vanadium
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- C—CHEMISTRY; METALLURGY
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- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/60—Ferrous alloys, e.g. steel alloys containing lead, selenium, tellurium, or antimony, or more than 0.04% by weight of sulfur
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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
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Abstract
The invention discloses a high-strength-toughness ultralow-temperature impact-resistant tubing head forging blank and a manufacturing method thereof, wherein the high-strength-toughness ultralow-temperature impact-resistant tubing head forging blank contains the following chemical components in percentage by mass: c: 0.30-0.40%, Si: 0.20 to 0.50%, Mn: 0.70-1.00%, Cr: 1.00-1.30%, Ni: 0.20 to 0.50%, Mo: 0.20-0.30%, V: 0.02-0.05%, Al: 0.02 to 0.05 percent of P, less than or equal to 0.012 percent of S, less than or equal to 0.005 percent of S, less than or equal to 0.015 percent of five-harmful element Sn, less than or equal to 0.015 percent of As, less than or equal to 0.015 percent of Pb, less than or equal to 0.015 percent of Sb, less than or equal to 0.015 percent of Bi, less than or equal to 1.5ppm of gas [ H ], [ 15ppm of O ], and less than or equal to 60ppm of [ N; the balance of Fe and other inevitable impurities; the component design of the invention has obvious superiority and high purity of steel, the structural uniformity of the forging can be obviously improved by forging under high pressure, and the strength, the toughness and the low-temperature impact resistance at minus 60 ℃ of the blank of the oil pipe head forging can be obviously improved.
Description
Technical Field
The invention relates to the technical field of steel materials, in particular to a high-strength-toughness ultralow-temperature impact-resistant tubing head forging blank and a manufacturing method thereof.
Background
The tubing head is mounted on top of the casing head cross-piece, and after the final casing is installed, the tubing head is mounted to provide a load step to support the tubing string and to provide a sealed bore for tubing hanger or production casing/tubing annulus sealing. After completion, the tree is reinstalled onto the top flange of the tubing head cross-piece by connecting the tubing head reducing nipple. The tubing head made of the common CrMo steel material has low strength and poor toughness, can resist low-temperature impact of less than-60 ℃, and is brittle-broken in some extreme environments, thereby causing major accidents of oil wells and causing well blowout to be scrapped seriously.
Disclosure of Invention
The invention aims to provide a high-strength-toughness ultralow-temperature impact-resistant tubing head forging blank and a manufacturing method thereof aiming at the defects in the prior art, wherein the production process flow is as follows: electric furnace smelting, LF refining, VD vacuum treatment, continuous casting process, heating, forging and heat treatment.
In order to achieve the purpose, the invention adopts the following technical scheme:
a high-strength-toughness ultralow-temperature impact-resistant tubing head forging blank comprises the following chemical components in percentage by mass: c: 0.30-0.40%, Si: 0.20 to 0.50%, Mn: 0.70-1.00%, Cr: 1.00-1.30%, Ni: 0.20 to 0.50%, Mo: 0.20-0.30%, V: 0.02-0.05%, Al: 0.02 to 0.05 percent of P, less than or equal to 0.012 percent of S, less than or equal to 0.005 percent of S, less than or equal to 0.015 percent of five-harmful element Sn, less than or equal to 0.015 percent of As, less than or equal to 0.015 percent of Pb, less than or equal to 0.015 percent of Sb, less than or equal to 0.015 percent of Bi, less than or equal to 1.5ppm of gas [ H ], [ 15ppm of O ], and less than or equal to 60ppm of [ N; the balance of Fe and other inevitable impurities.
The invention relates to a method for manufacturing a blank of a high-strength-toughness ultralow-temperature impact-resistant tubing head forging, which comprises the following steps of:
(1) electric furnace smelting: smelting in an electric arc furnace, adopting scrap steel and hot molten iron, wherein the proportion of the hot molten iron is more than or equal to 60 percent, and the total charging amount is 120 tons. The end point C is more than or equal to 0.07 percent, the P is less than or equal to 0.015 percent, and the residual elements meet the internal control requirement; the tapping temperature is 1640-1680 ℃. The tapping time of the electric furnace is more than or equal to 2.0 min; the residual steel amount of the electric furnace is more than or equal to 10 tons. Aluminum ingots, medium manganese, ferrosilicon and ferrochromium are adopted for deoxidation alloying, and silicon-manganese alloy is strictly forbidden to be added. Tapping and feeding sequence: aluminum ingot → medium manganese → ferrosilicon → ferrochrome → nickel plate → ferromolybdenum → ferrovanadium → active lime → premelting slag, the alloy is added according to the target components of C, Mn, Cr, Ni and Mo by 0.06 percent, the adding amount of the aluminum ingot is 1.2-1.6 kg/t, the adding amount of the lime is 6-8 kg/t, and the adding amount of the premelting slag is 6-8 kg/t. The addition amount of the alloy is properly adjusted according to the actual content of the alloy elements and the content of the residual elements in the molten steel of the electric furnace.
(2) LF refining: after the refining is in place, slag charge is added according to the slag condition, and the Al of the refined final slag is controlled2O320-31 percent and less than or equal to 0.5 percent of (FeO + MnO), and deoxidizing by using high-purity silicon carbide, wherein the adding amount is more than 1.0kg/t steel. Under the condition of good slagging, an appropriate amount of aluminum wires can be fed according to the deoxidation condition, and after fully stirring for 2min at the argon flow of 300-700 NL/min, a sample is taken for full analysis after soft blowing for 1 min. According to the analysis result of the primary sample, the contents of components such as C, Si, Mn, Cr, Ni, Mo, V and the like are adjusted according to the requirements of target components, the mixture is fully stirred for 1.5min by argon flow of 300-700 NL/min, and then the secondary sample is taken for analysis after soft blowing for 2 min. Before LF tapping, calcium wires are fed according to the length of 1.0-1.5 m/ton of steel, and then soft blowing is carried out for more than or equal to 2 min.
(3) Vacuum treatment in a VD furnace: and slagging off before entering a VD furnace. The vacuum degree is less than 67Pa, and the holding time is more than or equal to 12 minutes. The soft argon blowing time after VD treatment is not less than 15 minutes, and the stirring and cooling of the bare molten steel and the large argon amount are strictly forbidden during the soft argon blowing. Controlling the steel feeding temperature after soft argon blowing: a first furnace for continuous casting: 1579-1589 ℃, starting the second furnace: 1549-1569 ℃.
(4) Continuous casting protection pouring: the tundish is well baked and kept clean, and the baking temperature is more than or equal to 1100 ℃. The crystallizer meets the requirements of arc alignment and water gap alignment, and the nozzle atomization effect is good. The large ladle long nozzle is hermetically cast by using a graphite sealing gasket and argon blowing, the tundish is fully sealed, and argon is blown into the tundish before casting; the liquid level of the tundish is not less than 700mm, and the fluctuation of the liquid level of the crystallizer is less than or equal to +/-3 mm. The medium carbon alloy continuous casting covering slag is adopted, and a double-layer tundish covering agent is used. The superheat degree of the tundish in the normal heat is controlled according to a target of 15-30 ℃, and the temperature of the first tundish is as follows: 1534-1544 deg.C (heat exchange heat times minus 5 deg.C), and 1519-1529 deg.C for normal heat times. The temperature of the casting blank entering the tension leveler is more than or equal to 900 ℃. The electromagnetic stirring current of the crystallizer is controlled to be 250-300A, the frequency is controlled to be 1.0-2.0Hz, the electromagnetic stirring current at the tail end is controlled to be 100-150A, and the frequency is controlled to be 5.0-8.0 Hz. The temperature of the round billet with the diameter of 700mm entering a slow cooling pit is more than or equal to 750 ℃, and the pit discharging temperature is less than or equal to 100 ℃.
(5) Heating by a heating furnace: and (3) heating the round billet with the diameter of 700mm in a heating furnace to 1200-1230 ℃, wherein the heat preservation time is more than or equal to 1 hour.
(6) Free forging in a 5000-ton hydraulic press: and (3) freely forging the round billet with the diameter of 700mm in a hydraulic machine, adopting a three-pier and three-drawing process, and carrying out small reduction on the pier thickness of the first pass by 30mm, drawing length of the second pass by 30mm, drawing thickness of the third pass by 40mm, drawing length of the fourth pass by 45mm, drawing thickness of the fifth pass by 65mm, and drawing length of the sixth pass by 70 mm.
(7) And (3) heat treatment: and (3) carrying out integral heat treatment on the forged round billet, wherein the heat treatment process comprises normalizing, quenching (heating to 843-885 ℃ for heat preservation and then quenching with water or polymer), tempering (heating to 649-704 ℃ for heat preservation and then air cooling).
Compared with the prior art, the invention adopts the technical scheme to produce the beneficial effects that:
the component design of the invention has obvious superiority and high purity of steel, the structural uniformity of the forging can be obviously improved by forging under high pressure, the strength, the toughness and the low-temperature impact resistance at minus 60 ℃ of the blank of the oil pipe head forging can be obviously improved, the invention is used in various extreme environments, and the service life and the safety coefficient are greatly improved.
Detailed Description
The present invention will be further described with reference to the following examples.
Example 1
The chemical components and the mass percentage content of the high-strength-toughness ultralow-temperature impact-resistant tubing head forging blank in the embodiment are shown in table 1, and the balance of the components are Fe and inevitable impurities. Table 2 shows the mechanical properties of the examples. Table 3 shows the non-metallic inclusion grades of the examples.
The production process comprises electric furnace smelting, LF refining, VD vacuum treatment, continuous casting process, heating, forging and heat treatment, and the specific process steps are as follows:
(1) electric furnace smelting: smelting in an electric arc furnace, and adopting scrap steel and hot charging molten iron, wherein the proportion of the hot charging molten iron is 62 percent, and the total charging amount is 118 tons. The end point C is 0.08 percent, the P is 0.010 percent, and the residual elements meet the internal control requirement; the tapping temperature was 1650 ℃. Tapping time of the electric furnace is 3 min; the residual steel amount of the electric furnace is 10.5 tons. Aluminum ingots, medium manganese, ferrosilicon and ferrochromium are adopted for deoxidation alloying, and silicon-manganese alloy is strictly forbidden to be added. Tapping and feeding sequence: aluminum ingot → medium manganese → ferrosilicon → ferrochrome → nickel plate → ferromolybdenum → ferrovanadium → active lime → premelting slag, the alloy is added according to the target component of C, Mn, Cr, Ni and Mo by 0.06 percent, the adding amount of the aluminum ingot is 1.3kg/t, the adding amount of the lime is 6kg/t and the adding amount of the premelting slag is 7 kg/t. The addition amount of the alloy is properly adjusted according to the actual content of the alloy elements and the content of the residual elements in the molten steel of the electric furnace.
(2) LF refining: after the refining is in place, slag charge is added according to the slag condition, and the Al of the refined final slag is controlled2O322% and 0.3% of (FeO + MnO), and deoxidizing with high purity silicon carbide, and the addition amount is more than 1.0kg/t steel. Under the condition of good slagging, an appropriate amount of aluminum wires can be fed according to the deoxidation condition, and after fully stirring for 2min at the argon flow rate of 360NL/min, a sample is taken for full analysis after soft blowing for 1 min. According to the analysis result of the primary sample, the contents of components such as C, Si, Mn, Cr, Ni, Mo, V and the like are adjusted according to the requirements of target components, the mixture is fully stirred for 1.5min by argon flow 400NL/min, and then the secondary sample is taken for analysis after soft blowing for 2 min. Before LF tapping, calcium wires are fed according to the proportion of 1.2 m/ton steel, and then soft blowing is carried out for 3 min.
(3) Vacuum treatment in a VD furnace: and slagging off before entering a VD furnace. The vacuum was less than 67Pa hold time 15 minutes. And after VD treatment, soft argon blowing time is 16 minutes, and bare molten steel and large argon amount are strictly forbidden to be stirred and cooled during soft argon blowing. Controlling the temperature of steel feeding to 1559 ℃ after soft argon blowing.
(4) Continuous casting protection pouring: the tundish was baked well and kept clean, baking temperature 1120 ℃. The crystallizer meets the requirements of arc alignment and water gap alignment, and the nozzle atomization effect is good. The large ladle long nozzle is hermetically cast by using a graphite sealing gasket and argon blowing, the tundish is fully sealed, and argon is blown into the tundish before casting; the liquid level of the tundish is 720mm, and the fluctuation of the liquid level of the crystallizer is less than or equal to +/-3 mm. The medium carbon alloy continuous casting covering slag is adopted, and a double-layer tundish covering agent is used. The degree of superheat of the tundish is controlled according to a target of 20 ℃. The temperature of the casting blank entering the withdrawal and straightening unit is 915 ℃. The electromagnetic stirring current of the crystallizer is controlled at 280A, the frequency is controlled at 1.6Hz, the electromagnetic stirring current at the tail end is controlled at 130A, and the frequency is controlled at 5.0 Hz. The temperature of the round billet with the diameter of 700mm entering a slow cooling pit is 762 ℃, and the pit outlet temperature is less than 100 ℃.
(5) Heating by a heating furnace: the round billet with the diameter of 700mm enters a heating furnace to be heated to 1210 ℃, and the heat preservation time is 1.5 hours.
(6) Free forging in a 5000-ton hydraulic press: and (3) freely forging the round billet with the diameter of 700mm in a hydraulic machine, adopting a three-pier and three-drawing process, and carrying out small reduction on the pier thickness of the first pass by 30mm, drawing length of the second pass by 30mm, drawing thickness of the third pass by 40mm, drawing length of the fourth pass by 45mm, drawing thickness of the fifth pass by 65mm, and drawing length of the sixth pass by 70 mm.
(7) And (3) heat treatment: and (3) carrying out integral heat treatment on the forged round billet, wherein the heat treatment process comprises normalizing, quenching (heating to 855 ℃, keeping the temperature, quenching the polymer) and tempering (heating to 660 ℃, keeping the temperature, and then air cooling).
Example 2
The chemical components and the mass percentage content of the high-strength-toughness ultralow-temperature impact-resistant tubing head forging blank in the embodiment are shown in table 1, and the balance of the components are Fe and inevitable impurities. Table 2 shows the results of mechanical properties of the examples. Table 3 shows the non-metallic inclusion grades of the examples.
The production process comprises electric furnace smelting, LF refining, VD vacuum treatment, continuous casting process, heating, forging and heat treatment, and the specific process steps are as follows:
(1) electric furnace smelting: smelting in an electric arc furnace, and adopting scrap steel and hot charging molten iron, wherein the proportion of the hot charging molten iron is 60.6 percent, and the total charging amount is 119.3 tons. The end point C is 0.08 percent, the P is 0.011 percent, and the residual elements meet the internal control requirement; the tapping temperature was 1652 ℃. Tapping time of the electric furnace is 3.5 min; the residual steel amount of the electric furnace is 10.6 tons. Aluminum ingots, medium manganese, ferrosilicon and ferrochromium are adopted for deoxidation alloying, and silicon-manganese alloy is strictly forbidden to be added. Tapping and feeding sequence: aluminum ingot → medium manganese → ferrosilicon → ferrochrome → nickel plate → ferromolybdenum → ferrovanadium → active lime → premelting slag, the alloy is added according to the target component of C, Mn, Cr, Ni and Mo by 0.06 percent, the adding amount of the aluminum ingot is 1.5kg/t, the adding amount of the lime is 7.6kg/t and the adding amount of the premelting slag is 7.2 kg/t. The addition amount of the alloy is properly adjusted according to the actual content of the alloy elements and the content of the residual elements in the molten steel of the electric furnace.
(2) LF refining: after the refining is in place, slag charge is added according to the slag condition, and the Al of the refined final slag is controlled2O325%, (FeO + MnO) ═ 0.2%, and deoxygenation was performed using high purity silicon carbide, added at a level greater than 1.0kg/t steel. Under the condition of good slagging, an appropriate amount of aluminum wires can be fed according to the deoxidation condition, and after fully stirring for 2min at the argon flow of 380NL/min, a sample is taken for full analysis after soft blowing for 1 min. According to the analysis result of the primary sample, the contents of components such as C, Si, Mn, Cr, Ni, Mo, V and the like are adjusted according to the requirements of target components, the mixture is fully stirred for 1.5min by argon flow 410NL/min, and then the secondary sample is taken for analysis after soft blowing for 2 min. Before LF tapping, calcium wires are fed according to the proportion of 1.3 m/ton steel, and then soft blowing is carried out for 3.5 min.
(3) Vacuum treatment in a VD furnace: and slagging off before entering a VD furnace. The vacuum was less than 67Pa hold time 13 minutes. After VD treatment, the soft argon blowing time is 17 minutes, and the stirring and cooling of the bare molten steel and the large argon amount are strictly forbidden during the soft argon blowing. Controlling the temperature of steel feeding to 1555 ℃ after soft argon blowing.
(4) Continuous casting protection pouring: the tundish was baked well and kept clean at a baking temperature of 1125 ℃. The crystallizer meets the requirements of arc alignment and water gap alignment, and the nozzle atomization effect is good. The large ladle long nozzle is hermetically cast by using a graphite sealing gasket and argon blowing, the tundish is fully sealed, and argon is blown into the tundish before casting; the liquid level of the tundish is 730mm, and the fluctuation of the liquid level of the crystallizer is less than or equal to +/-3 mm. The medium carbon alloy continuous casting covering slag is adopted, and a double-layer tundish covering agent is used. The degree of superheat of the tundish is controlled according to a target of 21 ℃. The temperature of the casting blank entering the tension leveler is 920 ℃. The electromagnetic stirring current of the crystallizer is controlled to be 282A, the frequency is controlled to be 1.6Hz, the electromagnetic stirring current at the tail end is controlled to be 120A, and the frequency is controlled to be 5.0 Hz. The temperature of the round billet with the diameter of 700mm entering a slow cooling pit is 775 ℃, and the pit discharging temperature is less than 100 ℃.
(5) Heating by a heating furnace: the round billet with the diameter of 700mm enters a heating furnace to be heated to 1223 ℃, and the heat preservation time is 1.6 hours.
(6) Free forging in a 5000-ton hydraulic press: and (3) freely forging the round billet with the diameter of 700mm in a hydraulic machine, adopting a three-pier and three-drawing process, and carrying out small reduction on the pier thickness of the first pass by 30mm, drawing length of the second pass by 30mm, drawing thickness of the third pass by 40mm, drawing length of the fourth pass by 45mm, drawing thickness of the fifth pass by 65mm, and drawing length of the sixth pass by 70 mm.
(7) And (3) heat treatment: and (3) carrying out integral heat treatment on the forged round billet, wherein the heat treatment process comprises normalizing, quenching (heating to 860 ℃ for heat preservation and then polymer quenching), tempering (heating to 662 ℃ for heat preservation and then air cooling).
Example 3
The chemical components and the mass percentage content of the high-strength-toughness ultralow-temperature impact-resistant tubing head forging blank in the embodiment are shown in table 1, and the balance of the components are Fe and inevitable impurities. Table 2 shows the results of mechanical properties of the examples. Table 3 shows the non-metallic inclusion grades of the examples.
The production process comprises electric furnace smelting, LF refining, VD vacuum treatment, continuous casting process, heating, forging and heat treatment, and the specific process steps are as follows:
(1) electric furnace smelting: smelting in an electric arc furnace, and adopting scrap steel and hot charging molten iron, wherein the proportion of the hot charging molten iron is 61 percent, and the total charging amount is 120.3 tons. The end point C is 0.09 percent, the P is 0.013 percent, and residual elements meet the internal control requirement; the tapping temperature was 1646 ℃. Tapping time of the electric furnace is 4 min; the residual steel amount of the electric furnace is 10.8 tons. Aluminum ingots, medium manganese, ferrosilicon and ferrochromium are adopted for deoxidation alloying, and silicon-manganese alloy is strictly forbidden to be added. Tapping and feeding sequence: aluminum ingot → medium manganese → ferrosilicon → ferrochrome → nickel plate → ferromolybdenum → ferrovanadium → active lime → premelting slag, the alloy is added according to the target component of C, Mn, Cr, Ni and Mo by 0.06 percent, the adding amount of the aluminum ingot is 1.3kg/t, the adding amount of the lime is 7.2kg/t and the adding amount of the premelting slag is 7.3 kg/t. The addition amount of the alloy is properly adjusted according to the actual content of the alloy elements and the content of the residual elements in the molten steel of the electric furnace.
(2) LF refining: after the refining is in place, slag charge is added according to the slag condition, and the Al of the refined final slag is controlled2O324.5% and 0.4% of (FeO + MnO), and deoxidizing with high purity silicon carbide, the addition amount is more than 1.0kg/t steel. Under the condition of good slagging, an appropriate amount of aluminum wires can be fed according to the deoxidation condition, and after fully stirring for 2min by using the argon flow 410NL/min, a sample is taken for full analysis after soft blowing for 1 min. According to the analysis result of the primary sample, according to the target componentAdjusting the contents of C, Si, Mn, Cr, Ni, Mo, V and other components, fully stirring for 1.5min by argon flow of 420NL/min, soft blowing for 2min, and sampling for analysis. Before LF tapping, calcium wires are fed according to the proportion of 1.4 m/ton steel, and then soft blowing is carried out for 4 min.
(3) Vacuum treatment in a VD furnace: and slagging off before entering a VD furnace. The vacuum was less than 67Pa hold time 14 minutes. And after VD treatment, the soft argon blowing time is 18 minutes, and the stirring and cooling of the bare molten steel and the large argon amount are strictly forbidden during the soft argon blowing. After the soft argon blowing, the temperature of the upper steel is controlled to be 1560 ℃.
(4) Continuous casting protection pouring: the tundish was baked well and kept clean, baking temperature 1120 ℃. The crystallizer meets the requirements of arc alignment and water gap alignment, and the nozzle atomization effect is good. The large ladle long nozzle is hermetically cast by using a graphite sealing gasket and argon blowing, the tundish is fully sealed, and argon is blown into the tundish before casting; the liquid level of the tundish is 728mm, and the fluctuation of the liquid level of the crystallizer is less than or equal to +/-3 mm. The medium carbon alloy continuous casting covering slag is adopted, and a double-layer tundish covering agent is used. The degree of superheat of the tundish is controlled according to a target of 22 ℃. The temperature of the casting blank entering the tension leveler is 921 ℃. The electromagnetic stirring current of the crystallizer is controlled at 279A, the frequency is controlled at 1.5Hz, the electromagnetic stirring current at the tail end is controlled at 118A, and the frequency is controlled at 5.3 Hz. The temperature of the round billet with the diameter of 700mm entering a slow cooling pit is 763 ℃, and the pit outlet temperature is less than 100 ℃.
(5) Heating by a heating furnace: the round billet with the diameter of 700mm enters a heating furnace to be heated to 1213 ℃, and the heat preservation time is 1.4 hours.
(6) Free forging in a 5000-ton hydraulic press: and (3) freely forging the round billet with the diameter of 700mm in a hydraulic machine, adopting a three-pier and three-drawing process, and carrying out small reduction on the pier thickness of the first pass by 30mm, drawing length of the second pass by 30mm, drawing thickness of the third pass by 40mm, drawing length of the fourth pass by 45mm, drawing thickness of the fifth pass by 65mm, and drawing length of the sixth pass by 70 mm.
(7) And (3) heat treatment: and (3) carrying out integral heat treatment on the forged round billet, wherein the heat treatment process comprises normalizing, quenching (heating to 862 ℃ for heat preservation and then polymer quenching), tempering (heating to 658 ℃ for heat preservation and then air cooling).
Table 1 shows the chemical compositions of steels of examples of the present invention
Chemical composition | Example 1 | Example 2 | Example 3 |
C | 0.33% | 0.34% | 0.35% |
Si | 0.35% | 0.38% | 0.31% |
Mn | 0.84% | 0.88% | 0.90% |
P | 0.010% | 0.011% | 0.009% |
S | 0.003% | 0.002% | 0.003% |
Cr | 1.20% | 1.22% | 1.25% |
Ni | 0.30% | 0.28% | 0.23% |
Mo | 0.25% | 0.22% | 0.21% |
V | 0.035% | 0.030% | 0.040% |
Sn | 0.005% | 0.006% | 0.004% |
As | 0.004% | 0.005% | 0.003% |
Pb | 0.003% | 0.003% | 0.002% |
Sb | 0.004% | 0.001% | 0.002% |
Bi | 0.005% | 0.002% | 0.003% |
[H] | 1.2ppm | 1.1ppm | 1.0ppm |
[O] | 10ppm | 11ppm | 9ppm |
[N] | 55ppm | 50ppm | 48ppm |
Table 2 shows the mechanical properties
Tensile strength | Yield strength | Elongation percentage | Shrinkage rate | Impact at-60 ℃ | |
Example 1 | 872 | 663 | 32.5 | 51 | 56 |
Example 2 | 901 | 656 | 28 | 56 | 59 |
Example 3 | 895 | 687 | 27 | 52 | 57 |
Technical requirements | ≥675MPa | ≥530MPa | ≥20% | ≥41% | ≥30J |
TABLE 3 grades of non-metallic inclusions
As can be seen from the tables 2-3, the tensile strength of the obtained forging blank can be about 900MPa, the yield strength is increased by more than 200MPa compared with the technical requirement, the yield strength is increased by more than 650MPa, the yield strength is increased by more than 120MPa compared with the similar forging, other performance parameters are far higher than the technical requirement, and the remarkable technical effect is achieved.
The method can be realized by upper and lower limit values and interval values of intervals of process parameters (such as temperature, time and the like), and embodiments are not listed.
Conventional technical knowledge in the art can be used for the details which are not described in the present invention.
Finally, it should be noted that the above embodiments are only used for illustrating the technical solutions of the present invention and are not limited. Although the present invention has been described in detail with reference to the embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted without departing from the spirit and scope of the invention as defined in the appended claims.
Claims (6)
1. A high-strength and high-toughness ultralow-temperature impact-resistant tubing head forging blank is characterized in that: the forging blank comprises the following chemical components in percentage by mass: c: 0.30-0.40%, Si: 0.20 to 0.50%, Mn: 0.70-1.00%, Cr: 1.00-1.30%, Ni: 0.20 to 0.50%, Mo: 0.20-0.30%, V: 0.02-0.05%, Al: 0.02 to 0.05 percent of P, less than or equal to 0.012 percent of S, less than or equal to 0.005 percent of S, less than or equal to 0.015 percent of five-harmful element Sn, less than or equal to 0.015 percent of As, less than or equal to 0.015 percent of Pb, less than or equal to 0.015 percent of Sb, less than or equal to 0.015 percent of Bi, less than or equal to 1.5ppm of gas [ H ], [ 15ppm of O ], and less than or equal to 60ppm of [ N; the balance of Fe and other inevitable impurities.
2. A manufacturing method of a high-strength-toughness ultralow-temperature impact-resistant tubing head forging blank comprises the following steps:
(1) electric furnace smelting:
smelting in an electric arc furnace, wherein scrap steel and hot molten iron are adopted, the proportion of the hot molten iron is more than or equal to 60 percent, and the total charging amount is 120 tons; the end point C is more than or equal to 0.07 percent, the P is less than or equal to 0.015 percent, and the residual elements meet the internal control requirement; the tapping temperature is 1640-1680 ℃. The tapping time of the electric furnace is more than or equal to 2.0 min; the residual steel amount of the electric furnace is more than or equal to 10 tons;
(2) LF refining:
after the refining is in place, slag charge is added according to the slag condition, and the Al of the refined final slag is controlled2O320 to 31 percent of (FeO + MnO) and less than or equal to 0.5 percent of the total amount of the steel, and deoxidizing by using high-purity silicon carbide, wherein the adding amount of the silicon carbide is more than 1.0kg/t of steel; under the condition of good slagging, an appropriate amount of aluminum wires can be fed according to the deoxidation condition, and after fully stirring for 2min at the argon flow rate of 300-700 NL/min, a sample is taken for full analysis after soft blowing for 1 min; according to the analysis result of the primary sample, the contents of components such as C, Si, Mn, Cr, Ni, Mo, V and the like are adjusted according to the requirements of target components, after the argon flow is 300-700 NL/min and fully stirred for 1.5min, the secondary sample is taken for analysis after the soft blowing is carried out for 2 min; before LF tapping, feeding a calcium line according to the thickness of 1.0-1.5 m/ton steel, and then soft blowing for more than or equal to 2 min;
(3) vacuum treatment in a VD furnace:
slagging off before entering a VD furnace; the vacuum degree is less than 67Pa, and the holding time is more than or equal to 12 minutes; the soft argon blowing time after VD treatment is not less than 15 minutes, and the stirring and cooling of the bare molten steel and the large argon amount are strictly forbidden during the soft argon blowing; controlling the steel feeding temperature after soft argon blowing: a first furnace for continuous casting: 1579-1589 ℃, starting the second furnace: 1549-1569 ℃;
(4) continuous casting protection pouring:
the tundish is well baked and kept clean, and the baking temperature is more than or equal to 1100 ℃; the large ladle long nozzle is hermetically cast by using a graphite sealing gasket and argon blowing, the tundish is fully sealed, and argon is blown into the tundish before casting; the liquid level of the tundish is not lower than 700mm, and the fluctuation of the liquid level of the crystallizer is +/-3 mm; adopting medium carbon alloy continuous casting covering slag and using a double-layer tundish covering agent; the superheat degree of the tundish in the normal heat is controlled according to a target of 15-30 ℃, and the temperature of the first tundish is as follows: 1534-1544 ℃ and 1519-1529 ℃ of normal heat; the temperature of the casting blank entering a tension leveler is more than or equal to 900 ℃; the temperature of the round billet with the diameter of 700mm entering a slow cooling pit is more than or equal to 750 ℃, and the pit outlet temperature is less than or equal to 100 ℃;
(5) heating by a heating furnace:
heating the round billet with the diameter of 700mm in a heating furnace to 1200-1230 ℃, wherein the heat preservation time is more than or equal to 1 hour;
(6) hydraulic free forging:
the round billet with the diameter of 700mm enters a hydraulic machine for free forging, a three-pier and three-drawing process is adopted, the pier thickness of the first pass is reduced by 30mm, the drawing length of the second pass is reduced by 30mm, the pier thickness of the third pass is reduced by 40mm, the drawing length of the fourth pass is reduced by 45mm, the pier thickness of the fifth pass is reduced by 65mm, and the drawing length of the sixth pass is reduced by 70 mm;
(7) and (3) heat treatment:
and carrying out integral heat treatment on the forged round billet, wherein the heat treatment process comprises normalizing, quenching and tempering.
3. The manufacturing method according to claim 2, wherein in the step (2), aluminum ingots, medium manganese, ferrosilicon and ferrochrome are adopted for deoxidation alloying, and silicon-manganese alloy is strictly prohibited; tapping and feeding sequence: aluminum ingot → medium manganese → ferrosilicon → ferrochrome → nickel plate → ferromolybdenum → ferrovanadium → active lime → premelting slag, the alloy is added according to the target components of C, Mn, Cr, Ni and Mo by 0.06 percent, the adding amount of the aluminum ingot is 1.2-1.6 kg/t, the adding amount of the lime is 6-8 kg/t, and the adding amount of the premelting slag is 6-8 kg/t.
4. The manufacturing method as claimed in claim 2, wherein in the step (4), the electromagnetic stirring current of the crystallizer is controlled at 250-300A, the frequency is controlled at 1.0-2.0Hz, the electromagnetic stirring current at the end is controlled at 100-150A, and the frequency is controlled at 5.0-8.0 Hz.
5. The manufacturing method according to claim 2, wherein in the heat treatment of the step (7), the quenching is: heating to 843-885 ℃, keeping the temperature, quenching with water or polymer, and tempering: heating to 649-704 deg.C, keeping the temp. and air cooling.
6. The manufacturing method according to claim 2, wherein the forging blank manufactured by the above manufacturing method has mechanical properties of: the tensile strength is more than or equal to 675MPa, the yield strength is more than or equal to 530MPa, the elongation is more than or equal to 20 percent, and the shrinkage is more than or equal to 41 percent; the low-temperature impact energy at minus 60 ℃ is more than or equal to 30J; the impurity A is not more than 1.0 grade in fineness, the A is not more than 1.0 grade in thickness, the B is not more than 1.5 grade in fineness, the B is not more than 1.0 grade in thickness, the C is not more than 1.0 grade in fineness, the C is not more than 1.0 grade in thickness, the D is not more than 1.0 grade in fineness and the D is not more than 1.0 grade in thickness.
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