CN112322977A - Ultralow-temperature high-strength pressure vessel steel plate and production method thereof - Google Patents
Ultralow-temperature high-strength pressure vessel steel plate and production method thereof Download PDFInfo
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- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
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- C22C38/00—Ferrous alloys, e.g. steel alloys
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- C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
- C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
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- C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
- C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
- C21D8/0247—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the heat treatment
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- C22C38/04—Ferrous alloys, e.g. steel alloys containing manganese
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- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
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- 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
Abstract
The invention relates to an ultralow-temperature high-strength pressure vessel steel and a production method thereof, wherein the steel plate comprises the following chemical components in percentage by weight: c is less than or equal to 0.1%, Si: 0.15-0.45%, Mn: 0.3-0.8%, P is less than or equal to 0.01%, S is less than or equal to 0.005%, Ni: 3.25-3.70%, Cr: 0.15-0.2%, Mo is less than or equal to 0.12%, V is less than or equal to 0.05%, and the balance is Fe and inevitable impurities; ceq = C + Mn/6+ (Cr + Mo + V)/5+ (Cu + Ni)/15 ≤ 0.45; the production process adopts a heat treatment process of quenching and tempering, and controls the water temperature and water amount during quenching, the prepared steel plate has good mechanical property, the yield strength is more than or equal to 300MPa, the tensile strength is 480-.
Description
Technical Field
The invention relates to an ultralow temperature high-strength pressure vessel steel plate and a production method thereof, which are mainly used for manufacturing ultralow temperature equipment such as large-scale deep cooling storage tanks, pressure vessels and the like in the chemical field.
Background
With the development of modern industry, the world energy consumption is more and more concentrated on gaseous energy, especially natural gas, which is clean, convenient and efficient high-quality energy. The natural gas resources in the world are abundant, the reserves are estimated to be 400-billion cubic meters, and the natural gas resources can be developed for two or three hundred years according to the current annual output level. However, natural gas is typically stored at locations remote from the primary consumption area, making storage and long-distance transportation of large quantities of natural gas an urgent issue to be addressed. If the natural gas can be made into liquid, the volume can be reduced by 600 times, so that the transportation and storage cost of the natural gas is greatly reduced; the natural gas is usually liquefied at-162 ℃, and thus a large amount of steel for a cryogenic vessel is used for an LNG carrier for transporting the liquefied natural gas and a storage tank for storing the liquefied natural gas. The demand of Liquefied Natural Gas (LNG) as a green energy source in China is increasing, more than 20 LNG projects are built in China coastal and are to be built in the next decade, and a large amount of the projects are used for manufacturing LNG storage tanks by using low-temperature container steel plates.
The ultralow temperature high-strength pressure vessel steel plate is also widely applied to the industries of boilers, chemical engineering, power stations, petroleum and the like, and is used for the fields of equipment and components for manufacturing reactors, heat exchangers, separators, spherical tanks, gas tanks, liquefied gas tanks, nuclear reactor pressure shells, boiler drums, liquefied petroleum gas tanks, hydropower station high-pressure water pipes, turbine shells and the like.
Most of ultra-low temperature high-strength pressure vessel steel plates are produced by adopting a production mode of normalizing and tempering, and the steel plates produced by the production mode cannot reach the required performance along with the increase of the thickness. Through tests, the invention adopts the quenching and tempering processes to obtain good internal structure.
Disclosure of Invention
The invention aims to provide a steel plate for an ultralow temperature container pressure container and a production method thereof, wherein the provided steel plate has good mechanical properties, the yield strength is more than or equal to 300MPa, the tensile strength is 480-610MPa, and the elongation is more than or equal to 21 percent; the microstructure is a tempered sorbite structure, and the grain size is controlled to be 8 grades.
In order to achieve the purpose, the technical scheme provided by the invention is as follows:
the ultralow-temperature high-strength pressure vessel steel plate comprises the following chemical components in percentage by weight: c is less than or equal to 0.1%, Si: 0.15-0.45%, Mn: 0.3-0.8%, P is less than or equal to 0.01%, S is less than or equal to 0.005%, Ni: 3.25-3.70%, Cr: 0.15-0.2%, Mo is less than or equal to 0.12%, V is less than or equal to 0.05%, and the balance is Fe and inevitable impurities; ceq = C + Mn/6+ (Cr + Mo + V)/5+ (Cu + Ni)/15 ≤ 0.45.
The steel plate for the ultralow-temperature high-strength pressure vessel has the advantages that both the non-metallic inclusion A, B, C, D and the DS type inclusion are less than or equal to 1.5 grade, the A + C type inclusion is less than or equal to 2.5 grade, the B + D + DS type inclusion is less than or equal to 2.5 grade, and the sum is less than or equal to 4.5 grade.
The yield strength of the ultralow-temperature high-strength pressure vessel steel plate is more than or equal to 300MPa, the tensile strength is 480-610MPa, and the elongation is more than or equal to 21 percent; the microstructure is a tempered sorbite structure, and the grain size is controlled to be 8 grades.
The thickness of the ultralow-temperature high-strength pressure vessel steel plate is 70mm, 75mm and 85 mm.
The production method of the ultralow-temperature high-strength pressure vessel steel plate comprises the steps of smelting, casting, heating, rolling, water cooling, heat treatment and the like.
The invention relates to a production method of an ultralow-temperature high-strength pressure vessel steel plate, which comprises the following steps: in the steel-making and steel ingot casting process, in order to ensure the low-temperature impact property of the steel plate and the uniformity of the mechanical properties of the large-thickness steel plate at all positions, the harmful element P, S is controlled at a lower level, the molten steel is subjected to VD vacuum degassing treatment, the purity of the molten steel is improved, the content of inclusions is reduced, and the appearance of the inclusions is improved by the molten steel through a calcium treatment technology; the superheat degree of the steel ingot is kept at 25 ℃ in the casting process, and the segregation degree of elements in the steel plate is reduced.
The production method of the ultralow-temperature high-strength pressure vessel steel plate comprises the following steps of heating, airing for 30min before steel loading, and braising for 1 h; low-speed steel burning is adopted, the temperature rising speed is 90-100 ℃/h below 1000 ℃, the maximum heating temperature is 1200 ℃, and the temperature is reduced by 15-30 ℃ before tapping.
The invention relates to a production method of an ultralow-temperature high-strength pressure vessel steel plate, which comprises the following steps: the rolling process comprises the following steps: heating the steel ingot in a soaking pit furnace at the heating temperature of 1180-. The rough rolling start temperature is 1000-.
In the rolling procedure, intermediate water cooling is performed between the finish rolling and the rough rolling, and the rough rolled blank is cooled, so that the steel airing time is shortened.
The production method of the ultralow-temperature high-strength pressure vessel steel plate comprises the step of water cooling, wherein an intermediate water cooling method is adopted in the steel airing process, the temperature of the steel plate is returned to 600-750 ℃, the steel plate is stacked and slowly cooled after being off-line, and the slow cooling time is 24 hours, 32 hours, 40 hours or 48 hours.
The method for producing a steel sheet for an ultra-low temperature high-strength pressure vessel according to the present invention, wherein the heat treatment stepIn order to ensure various performance indexes of the steel plate, a quenching and tempering process is adopted, wherein the quenching temperature is as follows: 865 once again at 875 deg.C, keeping the temperature for 30-50 minutes, and taking out of the furnace at 4400m3V =2min/m in water volume per hour swings for 20min, the water temperature is required to be 15 ℃, and the surface temperature of the steel plate is reduced to the room temperature; tempering temperature: 615 ℃ and 625 ℃, keeping the temperature in the furnace for 3.7-4min/mm, and taking out of the furnace for air cooling.
The production method of the ultralow-temperature high-strength pressure vessel steel plate provided by the invention finally obtains the 70mm low-temperature high-strength vessel 08Ni3DR, and the mechanical property of the steel plate reaches the design standard: the yield strength is more than or equal to 300MPa, the tensile strength is 480-610MPa, and the elongation is more than or equal to 21 percent; the microstructure is a tempered sorbite structure, and the grain size is controlled to be 8 grades.
The invention adopts the modes of electric furnace and external refining and vacuum degassing for smelting, and the steel is fine-grained killed steel. By adopting a two-stage controlled rolling technology and adding a proper amount of alloy elements, the alloy elements play roles of solid solution strengthening, fine grain strengthening and precipitation strengthening, the mechanical property of the steel plate is improved, and the prepared steel plate has good low-temperature toughness, high yield strength and high tensile strength.
After the steel plate is fully heated, different cooling conditions are applied to obtain different structures; the faster the cooling rate, the lower the red return, and generally the higher the grain size. According to the requirements of different steel plate sizes and single weight, the water temperature and the water quantity need to be adjusted so as to obtain the required structure and performance.
The invention has the beneficial effects that: the technical scheme provided by the invention can improve the performance qualification rate and the performance stability of the ultralow-temperature high-strength pressure vessel steel plate with the thickness of more than or equal to 40 mm.
Drawings
FIG. 1 is a heat treatment process route diagram of the method for producing a steel plate for an ultra-low temperature high strength pressure vessel according to the present invention.
Detailed Description
Example 1
The composition of the steel plate material of the 08Ni3DR ultralow temperature high strength pressure vessel with the thickness of 70mm in the embodiment is shown in Table 1, and the mechanical properties of the steel plate are shown in Table 2.
The production process of the steel plate comprises the working procedures of smelting, casting, heating, rolling, water cooling and heat treatment, and the specific process steps are as follows:
(1) smelting and casting processes: the content of P, S is strictly controlled, the molten steel is subjected to VD vacuum degassing treatment, the purity of the molten steel is improved, the content of inclusions is reduced, and the appearance of the inclusions is improved by the molten steel through a calcium treatment technology; the superheat degree of the steel ingot is kept at 25 ℃ in the casting process, and the segregation degree of elements in the steel plate is reduced;
(2) a heating procedure: airing the furnace for 30min before steel loading, and stewing the steel for 1 h; adopting low-speed steel burning, wherein the heating rate is 100 ℃/h below 1000 ℃, and the maximum heating temperature is 1200 ℃; cooling to 15 ℃ before tapping to ensure uniform temperature of steel ingots;
(3) a rolling procedure: heating the steel ingot in a soaking pit furnace at 1200 ℃, adopting a two-stage controlled rolling technology, fully austenitizing the steel ingot, then taking the steel ingot out of the furnace for rolling, descaling the surface of high-pressure water, carrying out rough rolling, controlling the reduction amount of the first three passes to be 35%, cooling the steel by using intermediate water in the steel airing process, and increasing the difference between the surface temperature and the core temperature of the steel plate, thereby increasing the deformation amount of the core of the steel plate to a certain extent and improving the core structure of the steel plate; the rough rolling initial temperature is 1010 ℃, the rough rolling finishing temperature is 990 ℃, the second-stage initial rolling temperature is 900 ℃, the second-stage final rolling temperature is 720 ℃, and the stack is slowly cooled after rolling;
(4) a water cooling process: cooling by adopting intermediate water in the steel airing process, returning to 750 ℃, and stacking and slowly cooling the steel plates for 24 hours after the steel plates are off-line;
(5) the heat treatment process comprises the following steps: in order to ensure various performance indexes of the steel plate, a quenching and tempering process is adopted, wherein the quenching temperature is as follows: 870 ℃, heat preservation for 40 minutes, and discharging from the furnace at 4400m3V =2min/m in water volume per hour swings for 20min, the water temperature is 15 ℃, and the surface temperature of the steel plate is reduced to the room temperature; tempering temperature: keeping the temperature in the furnace for 4min/mm at 620 ℃, and discharging and air cooling.
The microstructure of the steel plate is a tempered sorbite structure, and the grain size is controlled to be 8 grades; the non-metallic inclusion A, B, C, D and the DS type inclusion of the steel plate are less than or equal to 1.5 grade, the A + C type is less than or equal to 2.5 grade, the B + D + DS type is less than or equal to 2.5 grade, and the sum is less than or equal to 4.5 grade.
Example 2
The composition of the steel plate material of the 08Ni3DR ultralow temperature high strength pressure vessel with the thickness of 70mm in the embodiment is shown in Table 1, and the mechanical properties of the steel plate are shown in Table 2.
The production process of the steel plate comprises the working procedures of smelting, casting, heating, rolling, water cooling and heat treatment, and the specific process steps are as follows:
(1) smelting: the content of P, S is strictly controlled, the molten steel is subjected to VD vacuum degassing treatment, the purity of the molten steel is improved, the content of inclusions is reduced, and the appearance of the inclusions is improved by the molten steel through a calcium treatment technology; the superheat degree of the steel ingot is kept at 25 ℃ in the casting process, and the segregation degree of elements in the steel plate is reduced;
(2) a heating procedure: airing the furnace for 30min before steel loading, and stewing the steel for 1 h; adopting low-speed steel burning, wherein the heating rate is 100 ℃/h below 1000 ℃, and the maximum heating temperature is 1200 ℃; cooling to 15 ℃ before tapping to ensure uniform temperature of steel ingots;
(3) a rolling procedure: heating the steel ingot by a soaking pit furnace at 1200 ℃, adopting a two-stage controlled rolling technology, fully austenitizing the steel ingot, then taking the steel ingot out of the furnace for rolling, descaling the surface of high-pressure water, carrying out rough rolling, controlling the rolling reduction of the first three passes to be more than 35 percent in order to improve the internal loosening defect of the steel plate, and increasing the difference between the surface temperature and the core temperature of the steel plate by adopting an intermediate water cooling technology in the steel airing process, thereby increasing the deformation of the core of the steel plate to a certain extent and improving the core structure of the steel plate; the rough rolling starting temperature is 1000 ℃, the rough rolling finishing temperature is 970 ℃, the second-stage starting temperature is 890 ℃, the second-stage finishing temperature is 730 ℃, and the stack is slowly cooled after rolling;
(4) a water cooling process: in the steel airing process, an intermediate water cooling method is adopted, the steel plate is turned to 750 ℃, and the steel plate is stacked and slowly cooled for 24 hours after being off-line;
(5) the heat treatment process comprises the following steps: in order to ensure various performance indexes of the steel plate, a quenching and tempering process is adopted, wherein the quenching temperature is as follows: preserving heat for 40 minutes at 865 ℃, and discharging from the furnace at 4400m3V =2min/m in water volume per hour swings for 20min, the water temperature is 15 ℃, and the surface temperature of the steel plate is reduced to the room temperature; tempering temperature: 615 ℃, keeping the temperature in the furnace for 3.8min/mm, and discharging and air cooling.
The microstructure of the steel plate is a tempered sorbite structure, and the grain size is controlled to be 8 grades; the non-metallic inclusion A, B, C, D and the DS type inclusion of the steel plate are less than or equal to 1.5 grade, the A + C type is less than or equal to 2.5 grade, the B + D + DS type is less than or equal to 2.5 grade, and the sum is less than or equal to 4.5 grade.
Example 3
The composition of the steel plate material of 08Ni3DR ultra-low temperature high strength pressure vessel with the thickness of 75mm in the embodiment is shown in Table 1, and the mechanical property of the steel plate is shown in Table 2.
The production process of the steel plate comprises the working procedures of smelting, casting, heating, rolling, water cooling and heat treatment, and the specific process steps are as follows:
(1) smelting: the content of P, S is strictly controlled, the molten steel is subjected to VD vacuum degassing treatment, the purity of the molten steel is improved, the content of inclusions is reduced, and the appearance of the inclusions is improved by the molten steel through a calcium treatment technology; the superheat degree of the steel ingot is kept at 25 ℃ in the casting process, and the segregation degree of elements in the steel plate is reduced;
(2) a heating procedure: airing the furnace for 30min before steel loading, and stewing the steel for 1 h; adopting low-speed steel burning, wherein the heating rate is 90 ℃/h below 1000 ℃, and the maximum heating temperature is 1200 ℃; cooling to 15 ℃ before tapping to ensure uniform temperature of steel ingots;
(3) a rolling procedure: heating the steel ingot in a soaking pit furnace at the temperature of 1190 ℃, performing two-stage controlled rolling technology, fully austenitizing the steel ingot, performing out-of-furnace rolling, descaling the surface of high-pressure water, performing rough rolling, controlling the rolling reduction of the first three passes to 35% in order to improve the internal loosening defect of the steel plate, and increasing the difference between the surface temperature and the core temperature of the steel plate by adopting an intermediate water cooling technology in the steel airing process, so that the deformation of the core of the steel plate is increased to a certain extent, and the core structure of the steel plate is improved; the rough rolling start temperature is 1020 ℃, the rough rolling end temperature is 990 ℃, the second-stage start temperature is 910 ℃, the second-stage finish temperature is 740 ℃, and the stack is slowly cooled after rolling;
(4) a water cooling process: in the steel airing process, an intermediate water cooling method is adopted, the steel plate is turned to 750 ℃, and the steel plate is stacked and slowly cooled for 40 hours after being off-line;
(5) the heat treatment process comprises the following steps: in order to ensure various performance indexes of the steel plate, a quenching and tempering process is adopted, wherein the quenching temperature is as follows: 875 ℃ and preserving heat for 40 minutes, and discharging from the furnace at 4400m3V =2min/m in water volume per hour swings for 20min, the water temperature is 15 ℃, and the surface temperature of the steel plate is reduced to the room temperature; tempering temperature: 625 deg.CKeeping the temperature in the furnace for 3.7min/mm, and discharging and air cooling.
The microstructure of the steel plate is a tempered sorbite structure, and the grain size is controlled to be 8 grades; the non-metallic inclusion A, B, C, D and the DS type inclusion of the steel plate are less than or equal to 1.5 grade, the A + C type is less than or equal to 2.5 grade, the B + D + DS type is less than or equal to 2.5 grade, and the sum is less than or equal to 4.5 grade.
Example 4
The composition of the steel plate material of 08Ni3DR ultra-low temperature high strength pressure vessel with the thickness of 75mm in the embodiment is shown in Table 1, and the mechanical property of the steel plate is shown in Table 2.
The production process of the steel plate comprises the working procedures of smelting, casting, heating, rolling, water cooling and heat treatment, and the specific process steps are as follows:
(1) smelting: the content of P, S is strictly controlled, the molten steel is subjected to VD vacuum degassing treatment, the purity of the molten steel is improved, the content of inclusions is reduced, and the appearance of the inclusions is improved by the molten steel through a calcium treatment technology; the superheat degree of the steel ingot is kept at 25 ℃ in the casting process, and the segregation degree of elements in the steel plate is reduced;
(2) a heating procedure: airing the furnace for 30min before steel loading, and stewing the steel for 1 h; adopting low-speed steel burning, wherein the heating rate is 90 ℃/h below 1000 ℃, and the maximum heating temperature is 1200 ℃; cooling to 15 ℃ before tapping to ensure uniform temperature of steel ingots;
(3) a rolling procedure: heating the steel ingot in a soaking pit furnace at 1180 ℃, performing two-stage controlled rolling technology, performing out-of-furnace rolling after the steel ingot is fully austenitized, descaling the surface of high-pressure water, performing rough rolling, controlling the rolling reduction of the first three passes to 35% in order to improve the internal loosening defect of the steel plate, and increasing the difference between the surface temperature and the core temperature of the steel plate by adopting an intermediate water cooling technology in the steel airing process, so that the deformation of the core of the steel plate is increased to a certain extent, and the core structure of the steel plate is improved; the rough rolling initial rolling temperature is 1010 ℃, the rough rolling finishing temperature is 990 ℃, the second-stage initial rolling temperature is 900 ℃, the second-stage final rolling temperature is 730 ℃, and the stack is slowly cooled after rolling;
(4) a water cooling process: in the steel airing process, an intermediate water cooling method is adopted, the steel plate is turned to 750 ℃, and the steel plate is stacked and slowly cooled for 24 hours after being off-line;
(5) the heat treatment process comprises the following steps: to ensure the steelThe performance indexes of the plate are as follows, quenching and tempering processes are adopted, and the quenching temperature is as follows: 870 ℃, heat preservation for 50 minutes, and discharging from the furnace at 4400m3V =2min/m in water volume per hour swings for 20min, the water temperature is 15 ℃, and the surface temperature of the steel plate is reduced to the room temperature; tempering temperature: 615 ℃, keeping the temperature in the furnace for 4.1min/mm, and discharging and air cooling.
The microstructure of the steel plate is a tempered sorbite structure, and the grain size is controlled to be 8 grades; the non-metallic inclusion A, B, C, D and the DS type inclusion of the steel plate are less than or equal to 1.5 grade, the A + C type is less than or equal to 2.5 grade, the B + D + DS type is less than or equal to 2.5 grade, and the sum is less than or equal to 4.5 grade.
Example 5
The composition of the steel plate material of the 08Ni3DR ultralow temperature high strength pressure vessel with the thickness of 70mm in the embodiment is shown in Table 1, and the mechanical properties of the steel plate are shown in Table 2.
The production process of the steel plate comprises the working procedures of smelting, casting, heating, rolling, water cooling and heat treatment, and the specific process steps are as follows:
(1) smelting: the content of P, S is strictly controlled, the molten steel is subjected to VD vacuum degassing treatment, the purity of the molten steel is improved, the content of inclusions is reduced, and the appearance of the inclusions is improved by the molten steel through a calcium treatment technology; the superheat degree of the steel ingot is kept at 25 ℃ in the casting process, and the segregation degree of elements in the steel plate is reduced;
(2) a heating procedure: airing the furnace for 30min before steel loading, and stewing the steel for 1 h; adopting low-speed steel burning, wherein the heating rate is 90 ℃/h below 1000 ℃, and the maximum heating temperature is 1200 ℃; cooling to 15 ℃ before tapping to ensure uniform temperature of steel ingots;
(3) a rolling procedure: the steel ingot is heated by a soaking pit furnace at 1180 ℃, a two-stage controlled rolling technology is adopted, the steel ingot is taken out of the furnace for rolling after being fully austenitized, descaling is carried out on the surface of high-pressure water, rough rolling is carried out, the rolling reduction in the first three passes is controlled to be 35%, the difference between the surface temperature and the core temperature of the steel plate is increased by adopting an intermediate water cooling technology in the steel airing process, so that the deformation of the core of the steel plate is increased to a certain extent, and the core structure of the steel plate is improved. The rough rolling initial rolling temperature is 1000 ℃, the rough rolling finishing temperature is 990 ℃, the second-stage initial rolling temperature is 910 ℃, the second-stage final rolling temperature is 740 ℃, and the stack is slowly cooled after rolling;
(4) a water cooling process: in the steel airing process, an intermediate water cooling method is adopted, the steel plate is turned to 750 ℃, and the steel plate is stacked and slowly cooled for 48 hours after being off-line;
(5) the heat treatment process comprises the following steps: in order to ensure various performance indexes of the steel plate, a quenching and tempering process is adopted, wherein the quenching temperature is as follows: 870 ℃, heat preservation for 30 minutes, and discharging from the furnace at 4400m3V =2min/m in water volume per hour swings for 20min, the water temperature is 15 ℃, and the surface temperature of the steel plate is reduced to the room temperature; tempering temperature: keeping the temperature in the furnace for 4min/mm at 625 ℃, and discharging and air cooling.
The microstructure of the steel plate is a tempered sorbite structure, and the grain size is controlled to be 8 grades; the non-metallic inclusion A, B, C, D and the DS type inclusion of the steel plate are less than or equal to 1.5 grade, the A + C type is less than or equal to 2.5 grade, the B + D + DS type is less than or equal to 2.5 grade, and the sum is less than or equal to 4.5 grade.
Example 6
The composition of the steel plate material of 08Ni3DR ultra-low temperature high strength pressure vessel with the thickness of 75mm in the embodiment is shown in Table 1, and the mechanical property of the steel plate is shown in Table 2.
The production process of the steel plate comprises the working procedures of smelting, casting, heating, rolling, water cooling and heat treatment, and the specific process steps are as follows:
(1) smelting: the content of P, S is strictly controlled, the molten steel is subjected to VD vacuum degassing treatment, the purity of the molten steel is improved, the content of inclusions is reduced, and the appearance of the inclusions is improved by the molten steel through a calcium treatment technology. The superheat degree of the steel ingot is kept at 25 ℃ in the casting process, and the segregation degree of elements in the steel plate is reduced;
(2) a heating procedure: airing the furnace for 30min before steel loading, and stewing the steel for 1 h; adopting low-speed steel burning, wherein the heating rate is 95 ℃/h below 1000 ℃, and the maximum heating temperature is 1200 ℃; cooling to 15 ℃ before tapping to ensure uniform temperature of steel ingots;
(3) the steel ingot is heated by a soaking pit furnace at 1200 ℃, a two-stage controlled rolling technology is adopted, the steel ingot is taken out of the furnace for rolling after being fully austenitized, descaling is carried out on the surface of high-pressure water, rough rolling is carried out, the rolling reduction of the first three passes is controlled to be 35 percent in order to improve the internal loosening defect of the steel plate, and an intermediate water cooling technology is adopted in the steel airing process to increase the difference between the surface temperature and the core temperature of the steel plate, so that the deformation of the core of the steel plate is increased to a certain extent, and. The rough rolling initial temperature is 1010 ℃, the rough rolling finishing temperature is 990 ℃, the second-stage initial temperature is 890 ℃, the second-stage final temperature is 720 ℃, and the stack is slowly cooled after rolling;
(4) a water cooling process: in the steel airing process, an intermediate water cooling method is adopted, the steel plate is turned to 750 ℃, and the steel plate is stacked and slowly cooled for 32 hours after being off-line;
(5) the heat treatment process comprises the following steps: in order to ensure various performance indexes of the steel plate, a quenching and tempering process is adopted, wherein the quenching temperature is as follows: 875 ℃ and preserving heat for 30 minutes, and discharging from the furnace at 4400m3V =2min/m in water volume per hour swings for 20min, the water temperature is 15 ℃, and the surface temperature of the steel plate is reduced to the room temperature; tempering temperature: keeping the temperature in the furnace for 4min/mm at 620 ℃, and discharging and air cooling.
The microstructure of the steel plate is a tempered sorbite structure, and the grain size is controlled to be 8 grades; the non-metallic inclusion A, B, C, D and the DS type inclusion of the steel plate are less than or equal to 1.5 grade, the A + C type is less than or equal to 2.5 grade, the B + D + DS type is less than or equal to 2.5 grade, and the sum is less than or equal to 4.5 grade.
Example 7
The composition of the steel plate material of the 08Ni3DR ultralow temperature high strength pressure vessel with the thickness of 80mm in the embodiment is shown in Table 1, and the mechanical properties of the steel plate are shown in Table 2.
The production process of the steel plate comprises the working procedures of smelting, casting, heating, rolling, water cooling and heat treatment, and the specific process steps are as follows:
(1) smelting: the content of P, S is strictly controlled, the molten steel is subjected to VD vacuum degassing treatment, the purity of the molten steel is improved, the content of inclusions is reduced, and the appearance of the inclusions is improved by the molten steel through a calcium treatment technology. The superheat degree of the steel ingot is kept at 25 ℃ in the casting process, and the segregation degree of elements in the steel plate is reduced;
(2) a heating procedure: airing the furnace for 30min before steel loading, and stewing the steel for 1 h; adopting low-speed steel burning, wherein the heating rate is 95 ℃/h below 1000 ℃, and the maximum heating temperature is 1200 ℃; cooling to 15 ℃ before tapping to ensure uniform temperature of steel ingots;
(3) a rolling procedure: the steel ingot is heated by a soaking pit furnace at the heating temperature of 1190 ℃, a two-stage controlled rolling technology is adopted, the steel ingot is taken out of the furnace for rolling after being fully austenitized, descaling is carried out on the surface of high-pressure water, rough rolling is carried out, the rolling reduction in the first three passes is controlled to be 35 percent, the difference between the surface temperature and the core temperature of the steel plate is increased by adopting an intermediate water cooling technology in the steel airing process, so that the deformation of the core of the steel plate is increased to a certain extent, and the core structure of the steel plate is improved. The rough rolling starting temperature is 1030 ℃, the rough rolling finishing temperature is 990 ℃, the second-stage starting temperature is 890 ℃, the second-stage finishing temperature is 720 ℃, and the stack is slowly cooled after rolling;
(4) a water cooling process: in the steel airing process, an intermediate water cooling method is adopted, the steel plate is turned to 750 ℃, and the steel plate is stacked and slowly cooled for 32 hours after being off-line;
(5) the heat treatment process comprises the following steps: in order to ensure various performance indexes of the steel plate, a quenching and tempering process is adopted, wherein the quenching temperature is as follows: 865 deg.C, holding for 50 min, taking out of the furnace at 4400m3V =2min/m in water volume per hour swings for 20min, the water temperature is 15 ℃, and the surface temperature of the steel plate is reduced to the room temperature; tempering temperature: keeping the temperature in the furnace for 3.8min/mm at 620 ℃, and discharging and air cooling.
The microstructure of the steel plate is a tempered sorbite structure, and the grain size is controlled to be 8 grades; the non-metallic inclusion A, B, C, D and the DS type inclusion of the steel plate are less than or equal to 1.5 grade, the A + C type is less than or equal to 2.5 grade, the B + D + DS type is less than or equal to 2.5 grade, and the sum is less than or equal to 4.5 grade.
Example 8
The composition of the steel plate material of the 08Ni3DR ultralow temperature high strength pressure vessel with the thickness of 80mm in the embodiment is shown in Table 1, and the mechanical properties of the steel plate are shown in Table 2.
The production process of the steel plate comprises the working procedures of smelting, casting, heating, rolling, water cooling and heat treatment, and the specific process steps are as follows:
(1) smelting: the content of P, S is strictly controlled, the molten steel is subjected to VD vacuum degassing treatment, the purity of the molten steel is improved, the content of inclusions is reduced, and the appearance of the inclusions is improved by the molten steel through a calcium treatment technology. The superheat degree of the steel ingot is kept at 25 ℃ in the casting process, and the segregation degree of elements in the steel plate is reduced;
(2) a heating procedure: airing the furnace for 30min before steel loading, and stewing the steel for 1 h; adopting low-speed steel burning, wherein the heating rate is 100 ℃/h below 1000 ℃, and the maximum heating temperature is 1200 ℃; cooling to 15 ℃ before tapping to ensure uniform temperature of steel ingots;
(3) the steel ingot is heated by a soaking pit furnace at the heating temperature of 1195 ℃, a two-stage controlled rolling technology is adopted, the steel ingot is taken out of the furnace for rolling after being fully austenitized, descaling is carried out on the surface of high-pressure water, rough rolling is carried out, the rolling reduction in the first three passes is controlled to be 35 percent, the difference between the surface temperature and the core temperature of the steel plate is increased by adopting an intermediate water cooling technology in the steel airing process, so that the deformation of the core of the steel plate is increased to a certain extent, and the core structure of the steel plate is improved. The rough rolling initial rolling temperature is 1000 ℃, the rough rolling finishing temperature is 990 ℃, the second-stage initial rolling temperature is 900 ℃, the second-stage final rolling temperature is 730 ℃, and the stack is slowly cooled after rolling;
(4) a water cooling process: in the steel airing process, an intermediate water cooling method is adopted, the steel plate is turned to 750 ℃, and the steel plate is stacked and slowly cooled for 24 hours after being off-line;
(5) the heat treatment process comprises the following steps: in order to ensure various performance indexes of the steel plate, a quenching and tempering process is adopted, wherein the quenching temperature is as follows: 870 ℃, heat preservation for 50 minutes, and discharging from the furnace at 4400m3V =2min/m in water volume per hour swings for 20min, the water temperature is required to be 15 ℃, and the surface temperature of the steel plate is reduced to the room temperature; tempering temperature: 615 ℃, keeping the temperature in the furnace for 3.9min/mm, and discharging and air cooling.
The microstructure of the steel plate is a tempered sorbite structure, and the grain size is controlled to be 8 grades; the non-metallic inclusion A, B, C, D and the DS type inclusion of the steel plate are less than or equal to 1.5 grade, the A + C type is less than or equal to 2.5 grade, the B + D + DS type is less than or equal to 2.5 grade, and the sum is less than or equal to 4.5 grade.
TABLE 1 chemical composition (wt%) of steel sheet of each example
TABLE 2 mechanical Properties of the steel sheets of the examples
Claims (10)
1. The utility model provides an ultra-low temperature high strength pressure vessel steel sheet which characterized in that: the steel plate comprises the following chemical components in percentage by weight: c is less than or equal to 0.1%, Si: 0.15-0.45%, Mn: 0.3-0.8%, P is less than or equal to 0.01%, S is less than or equal to 0.005%, Ni: 3.25-3.70%, Cr: 0.15-0.2%, Mo: less than or equal to 0.12 percent, V: less than or equal to 0.05 percent, and the balance of Fe and inevitable impurities; ceq = C + Mn/6+ (Cr + Mo + V)/5+ (Cu + Ni)/15 ≤ 0.45.
2. The ultra-low temperature high strength pressure vessel steel sheet as claimed in claim 1, wherein: the steel plate non-metal inclusion A, B, C, D and DS type inclusion are less than or equal to 1.5 grade, A + C type is less than or equal to 2.5 grade, B + D + DS type is less than or equal to 2.5 grade, and the sum is less than or equal to 4.5 grade.
3. The steel plate for the ultralow-temperature high-strength pressure vessel as claimed in claim 1, wherein the steel plate has a yield strength of 300MPa or more, a tensile strength of 480-610MPa or more, and an elongation of 21% or more; the microstructure is a tempered sorbite structure, and the grain size is controlled to be 8 grades.
4. The ultra-low temperature high strength pressure vessel steel sheet as claimed in claim 1, wherein the steel sheet has a thickness of 70mm, 75mm, 85 mm.
5. The method for producing a steel plate for an ultra-low temperature high strength pressure vessel as claimed in claim 1, comprising the steps of smelting, casting, heating, rolling, water cooling, heat treatment, etc., wherein:
the heat treatment process adopts a quenching and tempering process, and the quenching temperature is as follows: 865 once again at 875 deg.C, keeping the temperature for 30-50 minutes, and taking out of the furnace at 4400m3V =2min/m in water volume per hour swings for 20min, the water temperature is required to be 15 ℃, and the surface temperature of the steel plate is reduced to the room temperature; tempering temperature: 615 ℃ and 625 ℃, keeping the temperature in the furnace for 3.7-4min/mm, and taking out of the furnace for air cooling.
6. The method for producing an ultra-low temperature high strength pressure vessel steel sheet as claimed in claim 5, wherein the steel-making and ingot-casting process comprises: strictly controlling the content of harmful element P, S, and carrying out VD vacuum degassing treatment and calcium treatment on the molten steel; the steel ingot was kept at a superheat degree of 25 c during casting.
7. The method for manufacturing a steel plate for an ultra-low temperature high strength pressure vessel as claimed in claim 5, wherein: in the heating procedure, the furnace is dried for 30min before steel loading, and steel is braised for 1 h; low-speed steel burning is adopted, the temperature rising speed is 90-100 ℃/h below 1000 ℃, the maximum heating temperature is 1200 ℃, and the temperature is reduced by 15-30 ℃ before tapping.
8. The method for manufacturing an ultra-low temperature high strength pressure vessel steel sheet as claimed in claim 5, wherein the rolling process: heating the steel ingot in a soaking pit furnace at the heating temperature of 1180-; the rough rolling start temperature is 1000-.
9. The method for manufacturing a steel plate for an ultra-low temperature high strength pressure vessel as claimed in claim 8, wherein: and the intermediate water cooling is between the finish rolling and the rough rolling, and the blank opened by the rough rolling is cooled.
10. The method for manufacturing a steel plate for an ultra-low temperature high strength pressure vessel as claimed in claim 5, wherein: in the water cooling step, an intermediate water cooling method is adopted in the steel airing process, the temperature is returned to 600 ℃ and 750 ℃, and the steel plates are stacked and slowly cooled after being off line.
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|---|---|---|---|---|
| CN114737113A (en) * | 2022-03-24 | 2022-07-12 | 南京钢铁股份有限公司 | 3.5Ni steel and production method thereof |
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| CN110499458A (en) * | 2019-08-19 | 2019-11-26 | 舞阳钢铁有限责任公司 | The production method of big thickness ultra-wide DIWA353 steel plate |
| CN110791711A (en) * | 2019-11-14 | 2020-02-14 | 舞阳钢铁有限责任公司 | Production method of extra-thick VL E460-grade quenched and tempered high-strength ship plate |
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| JPH0525541A (en) * | 1991-07-17 | 1993-02-02 | Sumitomo Metal Ind Ltd | Production of non-ni-added-type steel plate having high toughness and high tensile strength |
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| CN114737113A (en) * | 2022-03-24 | 2022-07-12 | 南京钢铁股份有限公司 | 3.5Ni steel and production method thereof |
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