CN111041361A - Mechanical connecting sleeve of-165 ℃ low-temperature-resistant steel bar for LNG storage tank and production method - Google Patents

Mechanical connecting sleeve of-165 ℃ low-temperature-resistant steel bar for LNG storage tank and production method Download PDF

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CN111041361A
CN111041361A CN201911293030.5A CN201911293030A CN111041361A CN 111041361 A CN111041361 A CN 111041361A CN 201911293030 A CN201911293030 A CN 201911293030A CN 111041361 A CN111041361 A CN 111041361A
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equal
temperature
less
production method
sleeve
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CN111041361B (en
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郭湛
汪开忠
于同仁
姜婷
张晓瑞
余良其
宋祖峰
尹德福
徐雁
黄社清
张步海
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Maanshan Iron and Steel Co Ltd
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Priority to PCT/CN2020/135058 priority patent/WO2021121109A1/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
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23P—METAL-WORKING NOT OTHERWISE PROVIDED FOR; COMBINED OPERATIONS; UNIVERSAL MACHINE TOOLS
    • B23P15/00—Making specific metal objects by operations not covered by a single other subclass or a group in this subclass
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
    • C21C5/00—Manufacture of carbon-steel, e.g. plain mild steel, medium carbon steel or cast steel or stainless steel
    • C21C5/52—Manufacture of steel in electric furnaces
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
    • C21C7/00—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00
    • C21C7/10—Handling in a vacuum
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C33/00—Making ferrous alloys
    • C22C33/04—Making ferrous alloys by melting
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/04—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
    • C22C38/08—Ferrous alloys, e.g. steel alloys containing nickel
    • 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
    • C22C38/12—Ferrous alloys, e.g. steel alloys containing tungsten, tantalum, molybdenum, vanadium, or niobium
    • 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
    • Y02P10/10—Reduction of greenhouse gas [GHG] emissions
    • Y02P10/143—Reduction of greenhouse gas [GHG] emissions of methane [CH4]
    • 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

Abstract

The invention provides a mechanical connecting sleeve of a steel bar resisting a low temperature of-165 ℃ for an LNG storage tank and a production method, wherein the production method comprises the following steps: turning an inner circle and an outer circle of a sleeve parent metal, machining an inner tooth by a tapping machine, quenching and tempering to manufacture the sleeve; base material composition: 0.06-0.12% of C, 0.30-0.50% of Si, 1.30-1.80% of Mn, 1.00-2.50% of Ni, 0.060-1.000% of V, less than or equal to 0.010% of P, less than or equal to 0.010% of S, less than or equal to 0.00015% of H, less than or equal to 0.0015% of O, and the balance of Fe and impurity elements. The invention adopts the mechanical connecting sleeve produced by steel different from the prior art and controls the production method, and the produced sleeve can meet the requirement of low temperature resistance of-165 ℃ of the reinforced concrete structure of low-temperature storage tanks such as LNG and the like in China.

Description

Mechanical connecting sleeve of-165 ℃ low-temperature-resistant steel bar for LNG storage tank and production method
Technical Field
The invention belongs to a steel material for low temperature and a preparation process thereof, and particularly relates to a mechanical connecting sleeve of a steel bar for resisting the low temperature of-165 ℃ for an LNG storage tank and a production method thereof.
Background
The steel bars are often used as framework materials of reinforced concrete structures, have supporting and reinforcing effects on building structures, and are sometimes used in certain low-temperature environments, and a typical building structure is a Liquefied Natural Gas (LNG) storage tank. Usually, the LNG storage temperature is-165 ℃, and the property of the metal material at low temperature is greatly changed compared with the normal temperature state, so that the metal material with low temperature resistance is required to be selected to ensure the safety of the LNG storage tank. For a long time, the low-temperature steel bars need to be imported from foreign countries, and domestic horse steel and the like realize domestic batch application of the low-temperature steel bars at present.
The low-temperature steel bars are delivered in a fixed length mode, and are used after being mechanically connected through sleeves in construction. The design temperature of the LNG storage tank is-165 ℃, so that the sleeve is required to have good room temperature performance, and the LNG storage tank is required to have good toughness performance at-165 ℃ to ensure the safety of the storage tank when LNG leaks. With the increasing construction strength of the urban LNG storage tanks in coastal ports in China, the demand for the low-temperature steel bar mechanical connecting sleeve is increased, but the specific components and the preparation method of the steel for the low-temperature steel bar mechanical connecting sleeve are not published in China.
The low-temperature steel bar mechanical connecting sleeve has the following requirements:
(1) the room temperature mechanical property of the sleeve meets the requirement of a 500 MPa-level steel bar I-level sleeve in JG/J107-2016 mechanical connection technical specification of steel bars;
(2) normal temperature unidirectional stretching performance f of sleeveO maxThe steel bar is not less than 550MPa when broken or the sleeve is not less than 605MPa when damaged0≤0.1mm，AsgtMore than or equal to 6.0 percent; high stress repeated tension and compression performance f of sleeveO maxThe steel bar is not less than 550MPa when broken or the sleeve is not less than 605MPa when damaged20Less than or equal to 0.3 mm; large deformation repeated tension-compression performance f of sleeveO maxThe steel bar is not less than 550MPa when broken or the sleeve is not less than 605MPa when damaged4≤0.3mm，u8≤0.6mm。
(3) Mechanical property f of sleeve in one-way stretching at-165 DEG CO maxThe breaking of the steel bar is more than or equal to 635MPa or the damage of the sleeve is more than or equal to 700MPa, Asgt≥3.0％。
The invention relates to a steel bar connecting sleeve, application No. 201010209694.1, which comprises a cylindrical sleeve body, wherein the inner surface of the sleeve body is provided with internal threads, the outer surface of the sleeve body is longitudinally provided with a plurality of longitudinal ribs protruding outwards, and the steel bar connecting sleeve is characterized in that the ends of the longitudinal ribs are arranged in an inclined shape with smooth and reduced height. The height is smoothly reduced in a diagonal shape or a diagonal arc shape. The rib strength can be effectively improved, the connection firmness is further guaranteed, and meanwhile the effects of saving forging materials and reducing cost can be achieved. The invention provides a steel bar connecting sleeve, application number 201010608926.0, which comprises an inner through hole, wherein the outer surface of the sleeve is provided with wrench clamping positions, the wrench clamping positions are prismatic teeth, the number of the prismatic teeth is more than or equal to 4, the inner through hole is cylindrical, threads are arranged in the inner through hole, and the threads arranged in the inner through hole are meshed with the threads at the end of a steel bar. The cross-section outer surface of the steel bar connecting sleeve is in the shape of the multi-edge tooth, and the defects that the existing steel bar connecting sleeve is not easy to screw and slip caused by the round outer surface are overcome. But none can be used for mechanical connection of low temperature steel bars at-165 deg.c design temperature.
Disclosure of Invention
The mechanical connecting sleeve for the-165 ℃ low-temperature-resistant steel bars for the LNG storage tank and the production method thereof provided by the invention have the advantages that the room-temperature mechanical property of the produced sleeve meets the requirement of a 500 MPa-level steel bar I-level sleeve in JG/J107-O max635MPa or more or sleeve damage fO max≥700MPa，AsgtNot less than 3.0%.
The specific technical scheme of the invention is as follows:
a production method of a mechanical connecting sleeve of a steel bar resisting a low temperature of-165 ℃ for an LNG storage tank comprises the following steps:
1) preparing a base material for a mechanical connecting sleeve of a steel bar with low temperature of-165 ℃ for an LNG storage tank;
2) the base material is processed into a sleeve.
The base material for the mechanical connecting sleeve of the-165 ℃ low-temperature resistant steel bar for the LNG storage tank in the step 1) comprises the following components in percentage by weight:
0.06-0.12% of C, 0.30-0.50% of Si, 1.30-1.80% of Mn, 1.00-2.50% of Ni, 0.060-1.000% of V, less than or equal to 0.010% of P, less than or equal to 0.010% of S, less than or equal to 0.00015% of H, less than or equal to 0.0015% of O, and the balance of Fe and impurity elements.
Further, the step 1) comprises the following process flows:
electric arc furnace smelting → LF furnace refining → RH vacuum degassing → continuous casting square billet → forging round steel.
The step 1) is specifically as follows:
smelting in an electric arc furnace, wherein the content of the end point C is less than or equal to 0.05 percent, and the temperature is 1620-1660 ℃;
the argon flow in the refining of the LF furnace is 200 plus 600NL/min at the early stage of the refining of the LF furnace, the molten steel is preferably not greatly turned over, the argon flow in the later stage of the refining is 20-150NL/min, the liquid level of the molten steel is not exposed, the slag surface slightly fluctuates, the O content in the steel is controlled by feeding an aluminum wire at the later stage of the refining, and the outlet temperature of the LF furnace is 1635 plus 1650 ℃;
the RH vacuum degassing: the degree of vacuum in the RH furnace front period is less than or equal to 100 Pa, the holding time is more than or equal to 10 minutes, and the gas flow is increased by 800-1200 NL/min; the later-period holding time is more than or equal to 10 minutes, and the gas flow is increased by 600 NL/min; [H] when the temperature is less than or equal to 1.5ppm, the temperature is 1575-1585 ℃; starting argon blowing stirring, wherein the flow of argon is 20-150 standard liters per minute, so that the liquid level of steel is not exposed, and the slag surface fluctuates slightly;
the continuous casting square billet comprises the following specific steps: after the components are qualified, the mixture is continuously cast into 150mm2The superheat degree (temperature) of molten steel in a tundish of a square billet is less than or equal to 30 ℃;
the forged round steel specifically comprises the following steps: forging to round steel as the base material for making the sleeve, wherein the forging heating temperature is 1100-1300 ℃, the initial forging temperature is more than or equal to 1100 ℃, and the final forging temperature is more than or equal to 850 ℃.
The step 2) comprises the following processes: turning the inner circle and the outer circle → tapping the inner teeth by machining → quenching → tempering.
And selecting the type of the sleeve to be processed according to JG/T163-2013 sleeve for steel bar mechanical connection. Turning an outer circle by using a lathe, wherein the size precision is IT7-IT6, and the roughness value is Ra6.3-0.8 mu m; turning an inner circle by using a numerical control lathe, wherein the size precision is IT4-IT3, and the roughness value is Ra1.6-0.4 mu m; the tapping machine is adopted to process the inner teeth, the tooth inclination angle is 75 degrees, and the processing tolerance is less than or equal to 0.02P.
The quenching refers to heating to 880 ℃, preserving heat for 1h, and adopting water quenching treatment;
the tempering is heating to 550 ℃, preserving heat for 2 hours, and then air cooling to room temperature.
In the step 2), according to the sleeve model requirement of BB5 in JG/T163-2013 sleeve for steel bar mechanical connection, a sleeve parent metal is processed into a sleeve, and the sleeve is quenched at 880 ℃ for 1h to improve the strength, and tempered at 550 ℃ for 2h to improve the low-temperature toughness.
The steel of the invention has the following functions of elements:
carbon: at present, the C content of a common mechanical connecting sleeve is 0.42-0.47%, and the C content of the mechanical connecting sleeve is 0.06-0.12% by comprehensively considering the requirements of performance, particularly low-temperature toughness. The reduction of the C content is not only beneficial to the improvement of the low-temperature toughness of the steel, but also beneficial to the improvement of the corrosion resistance, the welding performance and the like.
Silicon: si is inexpensive, promotes the precipitation of proeutectoid ferrite in steel, has little influence on the formation of pearlite, and can increase A1、A3The critical point has strong solid solution strengthening effect, but the toughness is not good due to too high Si content, and the Si content is selected to be 0.30-0.50%.
Manganese: reduction of Mn by A1、A3At the critical point, the pearlite transformation is delayed, the ferrite transformation is also delayed, Mn has the effects of solid solution strengthening and hardenability improvement, and the content range of Mn is selected to be 1.30-1.80%.
Nickel: ni has the functions of refining the crystal grains of steel and improving the low-temperature performance of the steel, has the functions of solid solution strengthening and hardenability improvement, but is expensive, and the content range of Ni is selected to be 1.00-2.50%.
Vanadium: the invention adopts V as a microalloying element, and the addition of V is necessary for improving the strength of steel and ensuring the strength performance of the steel. V is rich resource in China, and V dissolved in austenite can remarkably increase the hardenability of steel, and precipitate carbide or carbonitride of V in ferrite, so that the steel has remarkable precipitation strengthening effect. The V content range is selected to be 0.060-1.000%.
Sulfur, phosphorus: s, P it is a harmful element in the steel used for the sleeve, the lower the requirement, the better, the invention is controlled by less than or equal to 0.010%.
Hydrogen, oxygen: H. o belongs to harmful gas, H can cause white point microcracks, and O forms oxide inclusions in steel, so that the low-temperature toughness of the material is reduced.
The mechanical connecting sleeve for the steel bar resisting the low temperature of-165 ℃ for the LNG storage tank is produced by the method.
The invention adopts the mechanical connecting sleeve produced by steel different from the prior art, can meet the requirement of low temperature resistance of-165 ℃ of the reinforced concrete structure of low temperature storage tanks such as LNG and the like in China by controlling the production method of the invention, and the room temperature mechanical property of the sleeve meets the requirement of a 500 MPa-level I-level sleeve of the steel bar in JG/J107-2016 (mechanical connection of reinforcing steel bars) technical specification, namely the sleeve is a sleeve at normal temperatureUniaxial tensile Property fO maxThe steel bar is not less than 550MPa when broken or the sleeve is not less than 605MPa when damaged0≤0.1mm，AsgtMore than or equal to 6.0 percent; high stress repeated tension and compression performance f of sleeveO maxThe steel bar is not less than 550MPa when broken or the sleeve is not less than 605MPa when damaged20Less than or equal to 0.3 mm; large deformation repeated tension-compression performance f of sleeveO maxThe steel bar is not less than 550MPa when broken or the sleeve is not less than 605MPa when damaged4≤0.3mm，u8Less than or equal to 0.6 mm; mechanical property f of sleeve in one-way stretching at-165 DEG CO maxThe breaking of the steel bar is more than or equal to 635MPa or the damage of the sleeve is more than or equal to 700MPa, Asgt≥3.0％。
Detailed Description
Example 1 to example 6
A production method of a mechanical connecting sleeve of a steel bar resisting a low temperature of-165 ℃ for an LNG storage tank comprises the following steps:
1) preparing a steel base material for a mechanical connecting sleeve of a-165 ℃ low-temperature-resistant steel bar for an LNG storage tank;
2) and processing the sleeve parent metal into a sleeve.
The specific process flow is as follows: electric arc furnace smelting → LF furnace refining → RH vacuum degassing → continuous casting square billet → forging round steel → turning inner and outer circles → tapping machine processing inner teeth → quenching → tempering.
Step 1) preparation of the parent metal is specifically as follows: smelting in an electric arc furnace, wherein the content of the end point C is less than or equal to 0.05 percent, and the temperature is 1620-1660 ℃; the argon flow in the early stage of LF furnace refining is 200 plus 600NL/min, the argon flow in the later stage of refining is 20-150NL/min, the liquid level of the steel is not exposed, the slag surface fluctuates slightly, the content of O in the steel is controlled by feeding an aluminum wire in the later stage of refining, and the outlet temperature of the LF furnace is 1635 plus 1650 ℃; the degree of vacuum in the RH furnace front period is less than or equal to 100 Pa, the holding time is more than or equal to 10 minutes, and the gas flow is increased by 800-1200 NL/min; the later-period holding time is more than or equal to 10 minutes, and the gas flow is increased by 600 NL/min; [H] and (3) when the steel liquid surface is not more than 1.5ppm, the temperature of the steel liquid surface is 1575-. After the components are qualified, the steel is continuously cast into a square billet, and the superheat degree (temperature) of the molten steel of a tundish is less than or equal to 30 ℃.
The steel for the minus 165 ℃ low-temperature-resistant steel bar mechanical connecting sleeve for the LNG storage tank adopts specific chemical components, 6-furnace steel is smelted according to the process, and the process control conditions of the electric arc furnace smelting process, the LF furnace process, the vacuum degassing process and the continuous casting process are shown in tables 1-2.
TABLE 1 smelting, LF and RH process control in examples 1-6 of the present invention
Figure BDA0002319750520000041
Figure BDA0002319750520000051
The square billet is forged into round steel serving as a base material for manufacturing the sleeve, the forging heating temperature is 1100-1300 ℃, the initial forging temperature is more than or equal to 1100 ℃, and the final forging temperature is more than or equal to 850 ℃.
TABLE 2 control of continuous casting and forging processes in examples 1 to 6 of the present invention
Figure BDA0002319750520000052
The chemical components of the steel for a mechanical coupling sleeve of-165 c low temperature resistant steel bars for LNG tanks used in examples 1 to 6 are shown in table 3, and the balance is iron and inevitable impurities.
TABLE 3 Components (unit: wt%) of inventive examples 1 to 6
Figure BDA0002319750520000053
The dimensional accuracy and tolerance of the steel processing sleeve models of examples 1-6 of the present invention are shown in table 4. Turning an outer circle by using a lathe, wherein the size precision is IT7-IT6, and the roughness value is Ra6.3-0.8 mu m; turning an inner circle by using a numerical control lathe, wherein the size precision is IT4-IT3, and the roughness value is Ra1.6-0.4 mu m; the tapping machine is adopted to process the inner teeth, the tooth inclination angle is 75 degrees, and the processing tolerance is less than or equal to 0.02P.
TABLE 4 physical dimensions and tolerances for examples 1-6 of the present invention
Figure BDA0002319750520000061
The uniaxial tensile mechanical properties of the steels of examples 1-6 of the present invention are shown in table 5.
TABLE 5 uniaxial tensile mechanical properties of the steels of examples 1 to 6 of the invention
Figure BDA0002319750520000062
Wherein R iseLFor yield strength, RmFor tensile strength, AgtTotal elongation at maximum force.
The uniaxial tensile mechanical properties of the sleeves produced in examples 1-6 of the invention are shown in table 6.
TABLE 6 unidirectional tensile mechanical properties of sleeves according to examples 1-6 of the present invention
Figure BDA0002319750520000063
Figure BDA0002319750520000071
Wherein f isO maxFor tensile strength, u0For residual deformation, AsgtTotal elongation at maximum force.
The high stress repeated tension and compression performance of the sleeves of examples 1-3 of the invention is shown in Table 7.
TABLE 7 high stress repeated tension and compression Properties of the sleeves of examples 1-6 of the present invention
Figure BDA0002319750520000072
Wherein f isO maxFor tensile strength, u20Is the residual deformation.
The large deformation repeated tension-compression performance of the sleeves of examples 1-6 of the invention is shown in Table 8.
TABLE 8 repeated large deformation tension-compression performance of sleeves according to examples 1 to 6 of the present invention
Figure BDA0002319750520000073
Figure BDA0002319750520000081
Wherein f isO maxFor tensile strength, u4、u8Is the residual deformation.
The mechanical properties of the sleeve of examples 1 to 6 of the present invention at a temperature of-165 ℃ are shown in Table 9.
TABLE 9 unidirectional tensile mechanical Properties of sleeves according to examples 1-6 of the present invention
Figure BDA0002319750520000082
Wherein R iseLFor yield strength, RmFor tensile strength, AgtTotal elongation at maximum force.
The uniaxial tensile properties at-165 ℃ of the sleeves of examples 1 to 6 of the invention are shown in Table 10.
TABLE 10 uniaxial tensile properties at-165 ℃ for sleeves of examples 1-6 of the invention
Figure BDA0002319750520000083
Wherein f isO maxFor tensile strength, AgtTotal elongation at maximum force.

Claims (10)

1. The production method of the mechanical connecting sleeve of the steel bar with the temperature of-165 ℃ for the LNG storage tank is characterized by comprising the following steps of:
1) preparing a base material for a mechanical connecting sleeve of a steel bar with low temperature of-165 ℃ for an LNG storage tank;
2) processing a base material into a sleeve;
the base material for the mechanical connecting sleeve of the-165 ℃ low-temperature resistant steel bar for the LNG storage tank in the step 1) comprises the following components in percentage by weight:
0.06-0.12% of C, 0.30-0.50% of Si, 1.30-1.80% of Mn, 1.00-2.50% of Ni, 0.060-1.000% of V, less than or equal to 0.010% of P, less than or equal to 0.010% of S, less than or equal to 0.00015% of H, less than or equal to 0.0015% of O, and the balance of Fe and impurity elements.
2. The production method according to claim 1, wherein step 1) comprises the following process flow:
electric arc furnace smelting → LF furnace refining → RH vacuum degassing → continuous casting square billet → forging round steel.
3. The method as claimed in claim 2, wherein the electric arc furnace is used for smelting, the end point C content is less than or equal to 0.05%, and the temperature is 1620-.
4. The production method as claimed in claim 2, wherein the LF furnace refining, the argon flow at the early stage of the LF furnace refining is 200-600NL/min, the argon flow at the later stage of the refining is 20-150NL/min, and the LF furnace outlet temperature is 1635-1650 ℃.
5. The production method according to claim 2, characterized in that the RH vacuum degassing: the degree of vacuum in the RH furnace front period is less than or equal to 100 Pa, the holding time is more than or equal to 10 minutes, and the gas flow is increased by 800-1200 NL/min; the later-period holding time is more than or equal to 10 minutes, and the gas flow is increased by 600 NL/min; [H] when the temperature is less than or equal to 1.5ppm, the temperature is 1575-1585 ℃; argon blowing stirring is started, and the flow of argon is 20-150 normal liters per minute.
6. The production method according to claim 2, characterized in that the continuous casting billet is in particular: continuously casting into square billet, and the superheat degree of molten steel in a tundish is less than or equal to 30 ℃.
7. The production method according to claim 2, wherein the forged round steel is specifically: the forging heating temperature is 1100-1300 ℃, the initial forging temperature is more than or equal to 1100 ℃, and the final forging temperature is more than or equal to 850 ℃.
8. The production method according to claim 1, wherein step 2) comprises the following process: turning the inner circle and the outer circle → tapping the inner teeth by a machine → quenching → tempering; the quenching refers to heating to 880 ℃, preserving heat for 1h, and adopting water quenching treatment.
9. The production method according to claim 8, wherein the tempering is heating to 550 ℃, keeping the temperature for 2 hours, and then cooling to room temperature.
10. A mechanical coupling sleeve for-165 ℃ cryogenic steel bars for LNG storage tanks produced by the method of any one of claims 1 to 9.
CN201911293030.5A 2019-12-16 2019-12-16 Mechanical connecting sleeve of-165 ℃ low-temperature-resistant steel bar for LNG storage tank and production method Active CN111041361B (en)

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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2021121109A1 (en) * 2019-12-16 2021-06-24 马鞍山钢铁股份有限公司 -165°c-low-temperature-resistant rebar mechanical connection coupler for lng storage tank and production method therefor
CN113265586A (en) * 2021-05-14 2021-08-17 广东韶钢松山股份有限公司 Sleeve for mechanically connecting low-temperature-resistant steel bars for LNG storage tank and manufacturing method

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CN113265586A (en) * 2021-05-14 2021-08-17 广东韶钢松山股份有限公司 Sleeve for mechanically connecting low-temperature-resistant steel bars for LNG storage tank and manufacturing method

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