CN113088812B - 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 PDF

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CN113088812B
CN113088812B CN202110274878.4A CN202110274878A CN113088812B CN 113088812 B CN113088812 B CN 113088812B CN 202110274878 A CN202110274878 A CN 202110274878A CN 113088812 B CN113088812 B CN 113088812B
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furnace
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CN113088812A (en
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李金浩
韩蕾蕾
李成浩
欧阳峥容
刘珊珊
郑桂芸
张海霞
马传庆
张利平
李月
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Shandong Iron and Steel Co Ltd
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Shandong Iron and Steel Co Ltd
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Priority to PCT/CN2021/118763 priority patent/WO2022193587A1/en
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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
    • 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
    • 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
    • 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
    • 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
    • C21D1/18—Hardening; Quenching with or without subsequent tempering
    • 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
    • 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
    • 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
    • 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
    • C21D6/008—Heat treatment of ferrous alloys containing Si
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D9/00—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
    • C21D9/0068—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for particular articles not mentioned below
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C33/00—Making ferrous alloys
    • C22C33/04—Making ferrous alloys by melting
    • C22C33/06—Making ferrous alloys by melting using master alloys
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/001—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
    • C22C38/002—Ferrous alloys, e.g. steel alloys containing In, Mg, or other elements not provided for in one single group C22C38/001 - C22C38/60
    • 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
    • C22C38/008—Ferrous alloys, e.g. steel alloys containing tin
    • 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
    • C22C38/44—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
    • C22C38/46—Ferrous alloys, e.g. steel alloys containing chromium with nickel with vanadium
    • 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
    • C22C38/60—Ferrous alloys, e.g. steel alloys containing lead, selenium, tellurium, or antimony, or more than 0.04% by weight of sulfur
    • 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
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  • Treatment Of Steel In Its Molten State (AREA)
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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 to 0.40%, si:0.20 to 0.50%, mn: 0.70-1.00%, cr:1.00 to 1.30%, ni:0.20 to 0.50%, mo:0.20 to 0.30%, V:0.02 to 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.

Description

High-strength-toughness ultralow-temperature impact-resistant tubing head forging blank and manufacturing method thereof
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 re-installed onto the top flange of the four-way tubing head joint by connecting the tubing head reducing joints. 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 to 0.40%, si:0.20 to 0.50%, mn:0.70 to 1.00%, cr:1.00 to 1.30%, ni:0.20 to 0.50%, mo:0.20 to 0.30%, V:0.02 to 0.05%, al:0.02 to 0.05 percent, less than or equal to 0.012 percent of P, less than or equal to 0.005 percent of S, less than or equal to 0.015 percent of harmful elements 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 ], [ O ] less than or equal to 15ppm, and [ N ] less than or equal to 60ppm; 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 2.0min; the residual steel amount of the electric furnace is more than or equal to 10 tons. Aluminum ingot, medium manganese, ferrosilicon and ferrochromium are adopted for deoxidation and 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 reduction of 0.06% of the target components of C, mn, cr, ni and Mo, 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 controlled 2 O 3 And the content of the silicon carbide is not more than 20 percent to 31 percent, the content of the FeO and the MnO is not more than 0.5 percent, and the silicon carbide is deoxidized by high-purity silicon carbide, and 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, the argon flow is 300-700 NL/min, the mixture is fully stirred for 2min, and a sample is taken for full analysis after the mixture is softly blown 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 at the argon flow rate of 300-700 NL/min, and then the secondary sample is taken for analysis after soft blowing for 2min. Before LF tapping, calcium wires are fed according to the weight of 1.0-1.5 m/ton steel, and then soft blowing is carried out for more than or equal to 2min.
(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 can meet 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 lower 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. Controlling the superheat degree of the tundish in the normal heat according to a target of 15-30 ℃, wherein the temperature of the first tundish furnace is as follows: 1534-1544 deg.C (5 deg.C lower than heat exchange heat) and 1519-1529 deg.C of normal heat. 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 5.0-8.0Hz. 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: the round billet with the diameter of 700mm enters a heating furnace to be heated to 1200-1230 ℃, and the heat preservation time is more than or equal to 1 hour.
(6) Free forging in a 5000-ton hydraulic press: and (3) allowing the round billet with the diameter of 700mm to enter a hydraulic press for free forging, adopting a three-pier and three-drawing process, and performing small rolling reduction on the round billet with the diameter of 30mm for the first pass, stretching rolling reduction on the round billet with the diameter of 30mm for the second pass, stretching rolling reduction on the round billet with the diameter of 40mm for the third pass, stretching rolling reduction on the round billet with the diameter of 45mm for the fourth pass, stretching rolling reduction on the round billet with the diameter of 65mm for the fifth pass and stretching rolling reduction on the round billet with the diameter of 70mm for the sixth pass.
(7) And (3) heat treatment: and carrying out integral heat treatment on the forged round blank, 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-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 levels 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 3min; 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 7kg/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 supplemented according to the slag condition, and the Al of the refined final slag is controlled 2 O 3 And (FeO + MnO) =0.3%, deoxidizing by using high-purity silicon carbide, and adding the silicon carbide in an amount of more than 1.0kg/t steel. Under the condition of good slagging, an appropriate amount of aluminum wire 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. Adjusting the contents of C, si, mn, cr, ni, mo, V, etc. according to the target component requirement based on the analysis result of the primary sample, stirring thoroughly for 1.5min with argon flow of 400NL/min, blowing for 2min, and taking outAnd (5) analyzing the secondary sample. 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 3min.
(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, the soft argon blowing time is 16 minutes, and the stirring and cooling of the bare molten steel and the large argon are strictly forbidden during the 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 superheat degree of the tundish is controlled according to a target of 20 ℃. The temperature of the casting blank entering the tension leveler 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 5.0Hz. 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) allowing the round billet with the diameter of 700mm to enter a hydraulic press for free forging, adopting a three-pier and three-drawing process, and performing small rolling reduction on the round billet with the diameter of 30mm for the first pass, stretching rolling reduction on the round billet with the diameter of 30mm for the second pass, stretching rolling reduction on the round billet with the diameter of 40mm for the third pass, stretching rolling reduction on the round billet with the diameter of 45mm for the fourth pass, stretching rolling reduction on the round billet with the diameter of 65mm for the fifth pass and stretching rolling reduction on the round billet with the diameter of 70mm for the sixth pass.
(7) And (3) heat treatment: and (3) carrying out integral heat treatment on the forged round blank, wherein the heat treatment process comprises normalizing, quenching (heating to 855 ℃, keeping the temperature, quenching the polymer), tempering (heating to 660 ℃, keeping the temperature, and cooling in air).
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 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 3.5min; the residual steel amount of the electric furnace is 10.6 tons. Aluminum ingot, medium manganese, ferrosilicon and ferrochromium are adopted for deoxidation and 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 reduction of 0.06% of the target components of C, mn, cr, ni and Mo, 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 7.2kg/t. The adding amount of the alloy is properly adjusted according to the actual content of the alloy element and the residual element content of the molten steel of the electric furnace.
(2) LF refining: after the refining is in place, slag charge is supplemented according to the slag condition, and the Al of the refined final slag is controlled 2 O 3 25%, (FeO + MnO) =0.2%, deoxidation using high purity silicon carbide, added in an amount greater than 1.0kg/t steel. Under the condition of good slagging, an appropriate amount of aluminum wire can be fed according to the deoxidation condition, and after fully stirring for 2min at the flow rate of 380NL/min of argon, 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 C, si, mn, cr, ni, mo, V and other components 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 2min. 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 3.5min.
(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. And 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 superheat degree of the middle package 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 at 282A, the frequency is controlled at 1.6Hz, the electromagnetic stirring current at the tail end is controlled at 120A, and the frequency is controlled at 5.0Hz. 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) allowing the round billet with the diameter of 700mm to enter a hydraulic machine for free forging, adopting a three-pier and three-drawing process, and carrying out small reduction on the pier thickness of the first pass by 30mm, drawing long reduction on the second pass by 30mm, drawing long reduction on the third pass by 40mm, drawing long reduction on the fourth pass by 45mm, drawing large reduction on the pier of the fifth pass by 65mm, and drawing long reduction on the sixth pass by 70mm.
(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 4min; 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 reduction of 0.06% of the target components of C, mn, cr, ni and Mo, 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 7.3kg/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 supplemented according to the slag condition, and the Al of the refined final slag is controlled 2 O 3 And (FeO + MnO) =24.5%, (FeO + MnO) =0.4%, and high-purity silicon carbide is used for deoxidation, and the addition amount of the high-purity silicon carbide 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, 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 420NL/min, and then the secondary sample is taken for analysis after soft blowing for 2min. 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 4min.
(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 can meet the requirements of arc alignment and water gap alignment, and the nozzle atomization effect is good. The 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 superheat degree 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 5.3Hz. The temperature of the round billet with the diameter of 700mm entering a slow cooling pit is 763 ℃, 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 1213 ℃, and the heat preservation time is 1.4 hours.
(6) Free forging in a 5000-ton hydraulic press: and (3) allowing the round billet with the diameter of 700mm to enter a hydraulic press for free forging, adopting a three-pier and three-drawing process, and performing small rolling reduction on the round billet with the diameter of 30mm for the first pass, stretching rolling reduction on the round billet with the diameter of 30mm for the second pass, stretching rolling reduction on the round billet with the diameter of 40mm for the third pass, stretching rolling reduction on the round billet with the diameter of 45mm for the fourth pass, stretching rolling reduction on the round billet with the diameter of 65mm for the fifth pass and stretching rolling reduction on the round billet with the diameter of 70mm for the sixth pass.
(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
Figure BDA0002976205180000071
Figure BDA0002976205180000081
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 of intervals of process parameters (such as temperature, time and the like) and interval values, 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 (5)

1. A manufacturing method of a high-strength-toughness ultralow-temperature impact-resistant tubing head forging blank is characterized by comprising the following steps of: the forging blank comprises the following chemical components in percentage by mass: c:0.30 to 0.40%, si:0.20 to 0.50%, mn: 0.70-1.00%, cr:1.00 to 1.30%, ni:0.20 to 0.50%, mo:0.20 to 0.30%, V:0.02 to 0.05%, al:0.02 to 0.05 percent, less than or equal to 0.012 percent of P, less than or equal to 0.005 percent of S, less than or equal to 0.015 percent of harmful elements 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 ], [ O ] less than or equal to 15ppm, and [ N ] less than or equal to 60ppm; the balance of Fe and other inevitable impurities;
the manufacturing method 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 2.0min; 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 supplemented according to the slag condition, and the Al of the refined final slag is controlled 2 O 3 20% -31%, and (FeO + MnO) is less than or equal to 0.5%, and high-purity silicon carbide is used for deoxidation, wherein the addition amount of the silicon carbide is more than 1.0kg/t steel; under the condition of good slagging, feeding a proper amount of aluminum wires according to the deoxidation condition, fully stirring for 2min at the argon flow of 300-700 NL/min, soft blowing for 1min, and taking a sample for full analysis; according to the analysis result of the primary sample, the component contents of C, si, mn, cr, ni, mo and V are adjusted according to the target component requirements, 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 2min; before LF tapping, calcium wires are fed according to the proportion of 1.0-1.5 m/ton steel, and then soft blowing is carried out for more than or equal to 2min;
(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 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; controlling the superheat degree of the tundish in the normal heat according to a target of 15-30 ℃, wherein the temperature of the first tundish furnace is as follows: 1534-1544 ℃ and 1519-1529 ℃ of normal heat; the temperature of the casting blank in 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 ℃, and keeping the temperature for more than or equal to 1 hour;
(6) Hydraulic free forging:
the round billet with the diameter of 700mm enters a hydraulic press to be freely forged, a three-pier and three-drawing process is adopted, the first-pass pier thickness is reduced by 30mm in small pressing, the second-pass drawing length is reduced by 30mm, the third-pass pier thickness is reduced by 40mm, the fourth-pass drawing length is reduced by 45mm, the fifth-pass pier thickness is reduced by 65mm, and the sixth-pass drawing length is reduced by 70mm;
(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.
2. The manufacturing method according to claim 1, wherein in the step (2), aluminum ingot, 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 reduction of 0.06% of the target components of C, mn, cr, ni and Mo, 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.
3. The manufacturing method according to claim 1, wherein in the step (4), 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 5.0-8.0Hz.
4. The manufacturing method according to claim 1, 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.
5. The manufacturing method according to claim 1, 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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