CN110878400A - High-strength low-temperature pressure vessel SA537CL2 steel plate and production method thereof - Google Patents
High-strength low-temperature pressure vessel SA537CL2 steel plate and production method thereof Download PDFInfo
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/02—Ferrous alloys, e.g. steel alloys containing silicon
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
- C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
- C21D8/0205—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips of ferrous alloys
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- 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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- 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
- C22C38/04—Ferrous alloys, e.g. steel alloys containing manganese
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- 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
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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
- C22C38/08—Ferrous alloys, e.g. steel alloys containing nickel
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- C22C38/12—Ferrous alloys, e.g. steel alloys containing tungsten, tantalum, molybdenum, vanadium, or niobium
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- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/14—Ferrous alloys, e.g. steel alloys containing titanium or zirconium
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D2211/00—Microstructure comprising significant phases
- C21D2211/002—Bainite
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D2211/00—Microstructure comprising significant phases
- C21D2211/005—Ferrite
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Abstract
The invention provides a SA537CL2 steel plate for a high-strength low-temperature pressure vessel and a production method thereof, wherein the steel plate comprises the following chemical components: C. si, Mn, P, S, Als, Nb, V, Ni, and Ti, with the balance being Fe and residual elements; the steel plate is subjected to quenching, sub-temperature quenching and high-temperature tempering heat treatment, and the obtained structure mainly comprises a bainite tempered structure and ferrite. The steel plate has reasonable combination of chemical components, ensures good mechanical property and welding property through a reasonable production method, has compact internal structure and low content of non-metallic inclusions and harmful elements, and meets the use and manufacture requirements of industrial high-strength low-temperature pressure vessels.
Description
Technical Field
The invention belongs to the technical field of wide and thick plate metallurgy, and particularly relates to a high-strength low-temperature pressure vessel SA537CL2 steel plate and a production method thereof.
Background
With the continuous development of the industry in China, the requirements of production, storage and transportation equipment of petroleum and chemical products are more and more. The steel plates used for manufacturing the devices have more and more excellent comprehensive mechanical property requirements, particularly the strength property and the low-temperature impact toughness.
SA537CL2 is a high-strength pressure container widely used for manufacturing equipment and components such as reaction heat exchangers, separators, spherical tanks, oil gas tanks, liquefied gas tanks, nuclear reactor pressure shells, boiler steam drums, hydropower station high-pressure water pipes, turbine volutes and the like. In recent years, Liquefied Petroleum Gas (LPG) has been used in large quantities because of its advantages of cleanliness, sanitation, convenient storage and transportation, high calorific value, etc. The main components of LPG are propane and butane, but their liquefaction temperature is below-40 ℃ and their expansion coefficient is high, 1L of LPG has a vaporization volume of 250L. Therefore, a pressure vessel for storing LPG must have high strength and excellent low-temperature impact toughness at impact temperatures of-40 ℃ or lower.
In conclusion, the SA537Cl2 super-thick steel plate with lower impact temperature toughness for the pressure container is developed to meet the market demands at home and abroad and replace imported similar products, so that the steel plate has positive practical significance.
Disclosure of Invention
The invention aims to provide a high-strength low-temperature pressure vessel SA537CL2 steel plate which has reasonable combination of chemical components, higher strength and excellent low-temperature impact toughness and meets the use and manufacture requirements of industrial high-strength low-temperature pressure vessels.
The invention also aims to provide a production method of the SA537CL2 steel plate of the high-strength low-temperature pressure vessel, which is convenient for tissue production in the technical field of wide and thick plate metallurgy, and can improve the internal quality and the comprehensive performance of the SA537CL2 steel plate of the high-strength low-temperature pressure vessel.
The invention is realized by adopting the following technical scheme for achieving the aim:
a high-strength low-temperature pressure vessel SA537CL2 steel plate comprises the following chemical components in percentage by mass: c: 0.10-0.13%, Si: 0.20-0.40%, Mn: 1.50-1.58%, P: less than or equal to 0.01 percent, S: less than or equal to 0.003 percent, Als: 0.020-0.035%, Nb: 0.035-0.045%, V: 0.04-0.05%, Ni: 0.18-0.25%, Ti: 0.010-0.015% and the balance of Fe and residual elements;
the steel plate is subjected to heat treatment of quenching, sub-temperature quenching and high-temperature tempering, and the obtained structure mainly comprises a bainite tempered structure and ferrite.
The grain size of the steel sheet structure is 10 th order.
The thickness of the steel plate is 60-150 mm.
In order to obtain the steel plate, the production method adopted by the invention comprises the following steps: hot metal pretreatment, converter smelting, LF refining, VD vacuum refining, die casting, heating, controlled rolling and controlled cooling, and heat treatment of quenching, sub-temperature quenching and high-temperature tempering; the heating procedure time is controlled to be T-h (steel ingot thickness) multiplied by 15min/cm, the temperature of a hearth before steel loading is controlled to be less than or equal to 800 ℃, preheating is carried out for 3h, the target heat preservation temperature of a high-temperature section is 1260, 1290 ℃, and the heat preservation time is 13 h;
the controlled rolling and controlled cooling adopts two stages of controlled rolling and controlled cooling, the first stage is rough rolling and controlled cooling, the rough rolling stage adopts high temperature, low speed and large pressure, the rolling starting temperature is 1260-1280 ℃, the pass controlled reduction is 50-60 mm, and the controlled cooling is to carry out pass watering by using high pressure water of a rolling mill; after rough rolling is finished, the thickness of the intermediate blank is 2-3 times of that of the finished steel plate; the second stage is finish rolling and controlled cooling, the rolling temperature of the second stage is at the non-recrystallization temperature (Tnr), multi-pass and small-reduction rolling is carried out, the intermediate billet enters ACC to be cooled for multiple times, the temperature of the intermediate billet is reduced to be below Tnr (non-recrystallization temperature), and the finishing temperature is controlled to be Ar3+10 ℃; and cooling the steel plate by the ACC after final rolling, and controlling the temperature of the red returning of the steel plate to be 580-620 ℃ after the ACC is discharged.
The quenching temperature is AC3+ (30-50) DEG C, namely 910-930 ℃, and the quenching time is set to be 1.8-2.4 min/mm; the sub-temperature quenching adopts AC3- (30-60) DEG C, namely 820-850 ℃, and the quenching time is set to be 1.8-2.2 min/mm; the high-temperature tempering heat treatment temperature is 580-650 ℃, and the tempering time is set to be 3.0-6.0 min/mm.
The beneficial effects of the high-strength low-temperature pressure vessel SA537CL2 steel plate and the production method thereof provided by the application comprise:
the optimized chemical components are the premise, and the reasonable production method is ensured to obtain the proper metallographic structure. The rolling reduction is controlled to be 50-60 mm in the rough rolling large reduction pass, water is pumped in the rolling mill by high pressure water in the pass, a layer of hard shell relative to the inner part is formed on the surface of the steel ingot, the large rolling force permeates into the steel ingot, the crystal grains at the center of the steel ingot are fully crushed, the internal defects are closed, and the crystal grains are refined. The finish rolling is to carry out plastic deformation at the non-recrystallization temperature, the grains are pressed to be long, and the ferrite, austenite dislocation and vacancy formed by the strip are increased, so that more nucleation particles are provided for the subsequent heat treatment; the quenching is used for refining grains, the sub-temperature quenching is used for obtaining a ferrite and bainite structure and further refining grains, the high-temperature tempering is used for obtaining a tempered bainite structure, and the ferrite and the tempered bainite are used for ensuring the low-temperature high impact energy.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings that are required to be used in the embodiments will be briefly described below, it should be understood that the following drawings only illustrate some embodiments of the present invention and therefore should not be considered as limiting the scope, and for those skilled in the art, other related drawings can be obtained according to the drawings without inventive efforts.
FIG. 1 is a metallographic structure of Bhui + F at a thickness of 1/4 of a SA537CL2 steel plate provided in example 1 of the present application.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. The examples, in which specific conditions are not specified, were conducted under conventional conditions or conditions recommended by the manufacturer. The reagents or instruments used are not indicated by the manufacturer, and are all conventional products available commercially.
The following specifically describes the SA537CL2 steel sheet provided in the examples of the present application and the production method thereof.
The SA537CL2 steel plate provided by the application comprises the following chemical components (unit, wt%) by mass: c: 0.10-0.13%, Si: 0.20-0.40%, Mn: 1.50-1.58%, P: less than or equal to 0.01 percent, S: less than or equal to 0.003 percent, Als: 0.020-0.035%, Nb: 0.035-0.045%, V: 0.04-0.05%, Ni: 0.18-0.25%, Ti: 0.010-0.015% and the balance of Fe and residual elements;
the thickness of the SA537CL2 steel plate is not less than 60mm, and preferably 60-150 mm. When the thickness of the steel plate is changed within the range of 60-150mm, the alloy composition in the chemical composition of the corresponding SA537CL2 steel plate is preferably changed from low to high.
In the alloy of chemical composition, Nb C, N, V C, N and Ti C, N precipitates are generated by Nb, V, Ti and C to form precipitation strengthening and improve the strength of the steel plate, then Nb, V and Ti can refine grains and prevent the grains from growing to form fine-grained strengthening, Ni is a pure solid solution element in the steel and has the function of obviously reducing the cold-brittleness transition temperature, Ni and Fe exist in α and gamma iron phases in a mutual solution mode, ferrite grains are refined through the adsorption effect of the Ni and the Fe in the grains, the impact toughness of the steel is improved, and then the Ni has stronger hardenability, so that a bainite structure can be obtained when the steel plate is quenched, and the bainite tempered structure with good comprehensive performance can be obtained after tempering.
Among the alloys of chemical composition, C, Mn, V can significantly improve the strength of the steel sheet, and particularly, V can improve the temper resistance of the steel sheet. However, the inventors found that if C and V are contained in a predetermined amount, the low-temperature impact properties are deteriorated. In order to secure the low-temperature impact property, it is necessary to control the content of C, V while securing the strength.
In conclusion, the high-strength low-temperature pressure vessel SA537CL2 steel plate provided by the application has reasonable chemical component components, and the strength is improved through precipitation strengthening and fine-grain strengthening of Nb, V and Ti. The low-temperature impact property of the steel plate is ensured by controlling the upper limit of the C, V content and adding Ni element.
In addition, the application also provides a production method of the SA537CL2 steel plate, which comprises the following steps:
the KR pretreatment is carried out on the molten iron, the molten iron arriving at a station is subjected to slag skimming before and after the KR pretreatment, the thickness of a slag layer on the liquid surface is less than or equal to 25mm, the S content in the molten iron is less than or equal to 0.008 wt%, the desulfurization period is less than or equal to 26min, and the desulfurization temperature drop is less than or equal to 22 ℃ after the molten iron is stirred and desulfurized by the.
Carrying out oxidation decarburization and dephosphorization treatment on molten iron in a converter, controlling the oxygen content to be about 1100ppm, controlling the early-stage converting lance position to be about 1.3m, controlling the middle-stage and later-stage converting lance position to be about 1.0m, controlling the primary-stage and later-stage converting lance positions to be about 1560 ℃, controlling the point blowing time to be less than or equal to 2min, carrying out point blowing for 2 times and controlling the target temperature to be 1630 ℃. At the smelting end point of the converter, the carbon content in the molten steel is less than or equal to 0.07 percent, and the phosphorus content is less than or equal to 0.008 percent. And a slag blocking cone is adopted to block slag before tapping is finished, so that slagging and rephosphorization are prevented.
Refining is carried out in an LF furnace, alloy components are proportioned, and slagging and S removal are carried out. The refining is carried out by heating for three times, wherein 1200Kg of lime and 120Kg of fluorite balls are added into the molten steel before heating, the molten steel is thrown into an aluminum wire for 350m, and then the temperature is rapidly increased for slagging. Secondly, alloy components in the molten steel are heated and adjusted, and the alloy components are controlled to be in the lower limit of the range. And thirdly, heating to finely adjust the components to be close to the target components, and controlling the temperature to be about 1620 ℃.
And (3) performing VD vacuum treatment, controlling the vacuum pumping of the VD furnace to be below 67Pa, and keeping the vacuum pumping for more than or equal to 20min, so that gas impurities such as N, H, O in the molten steel can be fully floated, and the cleanliness of the molten steel is improved. And controlling the temperature of the VD ex-station molten steel to be about 1585 ℃.
The casting process adopts water-cooling die casting with copper plate heat conduction, and the copper plate has good heat conductivity coefficient, so that the cooling speed of molten steel is increased. This can greatly reduce segregation during solidification, and obtain a cast steel ingot with uniform composition and excellent internal structure. Demoulding, cleaning and charging 12h after casting.
The heating time of the steel ingot is controlled to be T ═ h (steel ingot thickness) multiplied by 15 min/cm. The temperature of the furnace before steel charging is controlled to be less than or equal to 800 ℃, preheating is carried out for 3 hours, the temperature difference between the surface and the interior of the steel ingot is reduced, and surface cracks caused by overlarge temperature stress are avoided. The target temperature of the high temperature section is 1260, 1290 ℃, such as 1265 ℃, 1285 ℃ and 1280 ℃. The holding time is 13 h. By controlling the heating time and temperature of the steel ingot, the steel ingot is ensured to be uniformly burnt through, the deformation resistance is reduced, the alloy elements in the steel ingot can be fully dissolved, and the coarsening of austenite grains is also prevented.
The steel ingot rolling adopts two-stage controlled rolling and controlled cooling. In the rough rolling stage, high-temperature, low-speed and high-pressure reduction is carried out, and meanwhile, high-pressure dephosphorization water is used for cooling the surface of the steel ingot, so that differential temperature rolling is formed. The initial rolling temperature is 1260-1280 ℃, preferably 1270 ℃. The linear speed of the low-speed rolling mill is controlled to be 1.15 m/min. The rolling reduction of the large rolling pass is controlled to be 50-60 mm. And water is pumped by high-pressure water of the rolling mill for each pass, so that a layer of hard shell relative to the inside is formed on the surface of the steel ingot, the hard shell is favorable for the penetration of rolling force of the rolling mill, the pressing force can be ensured to be fully transmitted to the inside of the steel ingot, and the core crystal grains of the steel ingot are fully crushed. The thickness of the rough-rolled cold steel is controlled to be 250-300 mm, and the accumulated reduction rate of finish rolling is ensured to be more than or equal to 50%.
After rough rolling is finished, the intermediate billet enters ACC to be cooled for multiple times, so that the temperature of the intermediate billet is reduced to be lower than Tnr (non-recrystallization temperature), and the problems of poor low-temperature impact caused by finish rolling and mixed crystal are avoided. The inventor finds that the intermediate billet is cooled by water, and the cooling speed is higher than that in the air, so that the rolling yield is improved. And secondly, the intermediate blank is cooled quickly, so that the internal segregation of the steel plate can be improved, and the ductility and toughness of the quarter and half of the thickness of the steel plate are improved.
And the finish rolling adopts multi-pass and low-reduction rolling, the finish rolling temperature is controlled at Ar3+10 ℃, and Ar3 is the temperature at which austenite begins to transform when the steel plate is cooled. In the finish rolling process, the inventors found that the finish rolling temperature is high as the start rolling temperature of finish rolling is high, and that the low-temperature impact toughness of the steel sheet is poor when the finish rolling temperature is close to the upper limit of the non-recrystallized region, but that when the finish rolling temperature is low and is lower than the non-recrystallized region and close to Ar3, a coarse pro-eutectoid ferrite structure is generated inside the steel sheet, and the plasticity and toughness of the steel sheet deteriorate, resulting in the elongation and impact properties of the steel sheet being inadequate.
ACC controlled cooling ensures that the controlled rolling structure is uniformly and finely transformed, and avoids generating a coarse bainite structure. The temperature of the controlled cooling and the controlled re-reddening is controlled to be 580-620 ℃. The temperature of the reddening decreases as the thickness of the sheet increases.
Further, the rolled steel plate is subjected to heat treatment of quenching, sub-temperature quenching and high-temperature tempering.
The quenching adopts a high-temperature quenching process of AC3+ (30-50) DEG C, and AC3 is the temperature at which the internal structure is completely transformed into austenite in the heating process of the steel plate. The quenching temperature is 910-930 ℃, such as 915 ℃, 918 ℃, 923 ℃, 925 ℃ and the like. The heat preservation time of quenching can be set to be 1.8-2.4 min/mm, such as 1.9min/mm, 2.0min/mm, 2.2min/mm and 2.4min/mm according to the plate thickness. The larger the thickness, the larger the heating coefficient and the longer the heating time. The quenching temperature and the heat preservation time are sufficient to ensure the austenitization of the steel plate structure, so that the internal structure is uniform and single. Quenching is carried out by adopting a quenching machine, and the steel plate is taken out of the furnace and is quickly put into water to be cooled to normal temperature. The steel plate can not stay in the air for too long in the quenching process, so that the phenomenon that the air cooling speed is low and abnormal structures are generated is avoided. Secondly, the required flow of the high-pressure section of the quenching machine is maximum, the water flow of the 1 section of the high-pressure section of the quenching machine is adjusted to be 450m3/h, the water flow of the two sections of the high-pressure section is adjusted to be 300m3/h, and the water flow of the three sections is adjusted to be 250m 3/h. Fully ensures the maximum cooling speed of the steel plate, leads the structure obtained after quenching to be refined uniformly, and avoids overlarge difference of the structure of one fourth and one half of the surface of the steel plate. The main function of the heat treatment is to completely unify and refine the internal structure of the steel plate.
The sub-temperature quenching adopts a low-temperature quenching process of AC3- (30-60) DEG C. The quenching temperature is 820-850 ℃, such as 826 ℃, 828 ℃, 832 ℃, 836 ℃ and the like. The heat preservation time of quenching is set to be 1.8-2.2 min/mm, such as 1.9min/mm, 2.0min/mm and 2.2min/mm according to the plate thickness. The larger the thickness, the larger the heating coefficient and the longer the heating time. And similarly, the steel plate is discharged from the furnace and is quickly put into water, and the cooling speed of the quenching machine is adjusted to be maximum.
In the sub-temperature quenching heat treatment, the inventor finds that when the steel plate is heated to a temperature lower than AC3- (20-40), the steel plate mainly has two structures, namely an austenite structure which is completely transformed, and a ferrite structure which is about to be transformed. In the subsequent quenching water cooling process, austenite undergoes structure cooling transformation, while ferrite does not undergo transformation, and is directly preserved in the final state of the steel sheet. The ferrite structure has excellent plasticity and toughness, and the low-temperature impact property of the steel plate is ensured. The heat treatment mainly has the effect of increasing the proportion of ferrite in the internal structure of the steel plate, so that the low-temperature impact property of the steel plate is improved.
After the sub-temperature quenching, tempering heat treatment is carried out. The temperature of the tempering heat treatment is 580-650 ℃, such as 590 ℃, 600 ℃, 620 ℃, 630 ℃, 650 ℃ and the like. The tempering time is set to be 3.0-6.0 min/mm, such as 3.5min/mm, 4.0min/mm, 5.0min/mm, 6.0min/mm and the like. The tempering temperature needs to be determined in consideration of the overall properties of the steel sheet. The tempering temperature is too high, the tempering time is too long, and the strength of the steel plate is not enough. If the tempering time is short, the strength of the steel sheet is excessively high, but the impact properties are poor.
Air cooling and flattening after tempering. Air cooling to 350-400 ℃, then leveling and pressing the plate shape, and flattening the plate shape with the temperature by a flattening machine in the flattening process to ensure that the plate shape meets the use requirements of customers.
And after flattening, performing fire-cut finishing, surface inspection and internal flaw detection, and finally warehousing.
The high-strength low-temperature pressure container SA537CL2 produced by the process has the yield strength of more than or equal to 415MPa, the tensile strength of more than or equal to 550MPa, the elongation of more than or equal to 22 percent and the transverse impact energy of more than or equal to 120J at minus 60 ℃.
The features and properties of the present invention are described in further detail below with reference to examples.
Example 1
This example provides a SA537CL2 steel sheet (unit, wt%) with a thickness of 70 mm: c: 0.10%, Si: 0.30% of Mn: 1.50%, P: 0.008%, S: 0.002%, Als: 0.030%, Nb: 0.035%, V: 0.040%, Ni: 0.20%, and Ti: 0.012%, the balance being Fe and residual elements.
The production method comprises the following steps:
the KR pretreatment is carried out on the molten iron, the molten iron arriving at a station is subjected to slag skimming before and after the KR pretreatment, the thickness of a slag layer on the liquid surface is less than or equal to 25mm, the S content in the molten iron is less than or equal to 0.006 wt% after the molten iron is stirred and desulfurized by the KR, the desulfurization period is less than or equal to 25min, and the desulfurization temperature drop is less than or equal.
In the smelting process of the converter, the oxygen content is controlled to be about 1100ppm, the blowing lance position at the early stage is controlled to be about 1.3m, the blowing lance position at the middle and later stages is controlled to be about 1.0m, the first-falling temperature is about 1560 ℃, the point blowing time is less than or equal to 2min, the point blowing is carried out for 2 times, and the target temperature is 1630 ℃. At the smelting end point of the converter, the carbon content in the molten steel is less than or equal to 0.07 percent, and the phosphorus content is less than or equal to 0.008 percent. And a slag blocking cone is adopted to block slag before tapping is finished, so that slagging and rephosphorization are prevented.
The refining adopts an LF furnace, the molten steel is heated, 1200Kg of lime and 120Kg of fluorite balls are added into the molten steel, the molten steel is thrown into an aluminum wire for 350m, and then the temperature is rapidly increased for slagging. And secondly, controlling the alloy composition to be in the lower limit of the range. And thirdly, heating the fine tuning component to enable the fine tuning component to approach the target component. And (3) carrying out vacuum treatment on the VD furnace, controlling the vacuum pumping of the VD furnace to be below 67Pa, keeping for 20min, and controlling the temperature of the molten steel leaving the VD furnace to be about 1585 ℃.
Demoulding, cleaning and charging 12h after casting. The temperature of a furnace hearth before steel charging is controlled to be less than or equal to 800 ℃, preheating is carried out for 3 hours, the target heat preservation temperature of a high-temperature section is 1270 ℃, and the heat preservation time is 13 hours.
The rolling was then carried out on a 3800 rolling mill at a start rolling temperature of 1260 ℃. The linear speed of the rolling mill is controlled at 1.15 m/min. The rolling reduction is controlled to be 55 mm/pass in the large rolling pass, the thickness of the rough-rolled cold steel is controlled to be 250mm, the rolling temperature of the finish rolling is controlled to be 770 ℃, and the temperature of the finish rolling is controlled to be 760 ℃. The steel plate water temperature is 760 ℃, and the ACC controlled cooling and red returning temperature is 615 ℃.
The quenching temperature is 923 ℃, and the heat preservation time of quenching is set to be 2.0 min/mm. The sub-temperature quenching temperature is 830 ℃, and the heat preservation time is 1.9 min/mm. The tempering temperature is 635 ℃, and the tempering time is set to be 5.5 min/mm.
Then air-cooling to 360 ℃, and then flattening with temperature. And finally finishing, inspecting, detecting defects and warehousing.
Example 2
This example provides a SA537CL2 steel sheet (unit, wt%) with a thickness of 120 mm: c: 0.12%, Si: 0.30%, Mn: 1.53%, P: 0.008%, S: 0.002%, Als: 0.031%, Nb: 0.040%, V: 0.043%, Ni: 0.22%, and Ti: 0.012%, the balance being Fe and residual elements.
The manufacturing method of the SA537CL2 steel plate is different from that in example 1 in that: the thickness of the rolled cold steel is 260mm, and the ACC re-reddening temperature is controlled at 600 ℃. The quenching temperature is 925 ℃, and the heat preservation time of quenching is set to be 2.1 min/mm. The sub-temperature quenching temperature is 835 ℃, and the heat preservation time is 2.0 min/mm. The tempering temperature is 615 ℃, and the tempering time is set to be 5.0 min/mm. The rest of the production is the same as the engineering process.
Example 3
This example provides a SA537CL2 steel sheet (unit, wt%) with a thickness of 150 mm: c: 0.13%, Si: 0.30%, Mn: 1.56%, P: 0.008%, S: 0.002%, Als: 0.032%, Nb: 0.043%, V: 0.048%, Ni: 0.24%, and Ti: 0.012%, the balance being Fe and residual elements.
The manufacturing method of the SA537CL2 steel plate is different from that in example 1 in that: the thickness of the rolled cold steel is 300mm, and the ACC re-reddening temperature is controlled to be 585 ℃. The quenching temperature is 928 ℃, and the heat preservation time of quenching is set to be 2.2 min/mm. The sub-temperature quenching temperature is 845 ℃, and the heat preservation time is 2.1 min/mm. The tempering temperature is 600 ℃, and the tempering time is set to be 4.0 min/mm. The rest of the production is the same as the engineering process. Air cooling to 400 ℃ after tempering, and flattening with temperature.
Examples of the experiments
The SA537CL2 plate obtained in example 1-3 was used as a sample, and the chemical composition and mechanical properties of the steel plate, the sample sampling position and the sample preparation were performed according to the standard GB/T2975. The low-temperature impact toughness test is carried out according to the GB/T229 standard, the tensile property test is carried out according to the GB/T228 standard, and the bending property test is carried out according to the GB/T232 standard. The results of the measurements are shown in Table 1 below.
TABLE 1 test results
As can be seen from Table 1, the SA537CL2 steel sheets for high-strength low-temperature pressure vessels with different thicknesses provided in examples 1 to 3 of the present application have good strength properties and low-temperature impact properties.
In example 1, the metallographic structure of one fourth was as shown in fig. 1, and the total level of inclusions was low, the matrix structure was bainite tempered structure + ferrite, and the grain size was 10.0. The fine bainite structure and the refined grains provide good comprehensive mechanical properties for the steel plate.
From the above test results, it can be seen that the component structure, impurity content and performance index of the SA537CL2 steel sheet for high-strength low-temperature pressure vessels provided in the examples of the present application all satisfy the requirements of the SA537CL2 steel sheet.
In addition, the surface inspection and internal flaw detection yield of the SA537CL2 steel plate reach 100.00 percent.
In some embodiments, the steel plate has a yield strength of 415MPa or more, a tensile strength of 550MPa or more, an elongation of 22% or more, and a transverse impact energy of 120J or more at-60 ℃.
In summary, the high-strength low-temperature pressure vessel SA537CL2 steel provided by the application has reasonable combination of chemical components, production process and internal structure, and can have strong strength performance and low-temperature impact performance. The production method is simple and easy to operate, and is beneficial to improving the quality of the SA537CL2 steel plate and improving the service performance of the steel plate.
The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (5)
1. A high-strength low-temperature pressure vessel SA537CL2 steel plate is characterized by comprising the following chemical components in percentage by mass: c: 0.10-0.13%, Si: 0.20-0.40%, Mn: 1.50-1.58%, P: less than or equal to 0.01 percent, S: less than or equal to 0.003 percent, Als: 0.020-0.035%, Nb: 0.035-0.045%, V: 0.04-0.05%, Ni: 0.18-0.25%, Ti: 0.010-0.015% and the balance of Fe and residual elements; the steel plate is subjected to heat treatment of quenching, sub-temperature quenching and high-temperature tempering, and the obtained structure mainly comprises a bainite tempered structure and ferrite.
2. The high-strength low-temperature pressure vessel SA537CL2 steel plate according to claim 1, wherein the grain size of the steel plate structure is grade 10.
3. The high strength low temperature pressure vessel SA537CL2 steel plate of claim 1, characterized in that the steel plate has a thickness of 60-150 mm.
4. A high strength low temperature pressure vessel SA537CL2 steel plate according to claim 1, characterized by yield strength not less than 415MPa, tensile strength not less than 550MPa, elongation not less than 22%, -60 ℃ transverse impact energy not less than 120J.
5. A production method of the high-strength low-temperature pressure vessel SA537CL2 steel plate as claimed in claims 1-4, comprising the following steps: hot metal pretreatment, converter smelting, LF refining, VD vacuum refining, die casting, heating, controlled rolling and controlled cooling, and heat treatment of quenching, sub-temperature quenching and high-temperature tempering; the method is characterized in that:
the heating procedure time is controlled to be T-h (steel ingot thickness) multiplied by 15min/cm, the temperature of a hearth before steel loading is controlled to be less than or equal to 800 ℃, preheating is carried out for 3h, the target heat preservation temperature of a high-temperature section is 1260, 1290 ℃, and the heat preservation time is 13 h;
the controlled rolling and controlled cooling adopts two stages of controlled rolling and controlled cooling, the first stage is rough rolling and controlled cooling, the rough rolling stage adopts high temperature, low speed and large pressure, the rolling starting temperature is 1260-1280 ℃, the pass controlled reduction is 50-60 mm, and the controlled cooling is to carry out pass watering by using high pressure water of a rolling mill; after rough rolling is finished, the thickness of the intermediate blank is 2-3 times of that of the finished steel plate; the second stage is finish rolling and controlled cooling, the rolling temperature of the second stage is at the non-recrystallization temperature (Tnr), multi-pass and small-reduction rolling is carried out, the intermediate billet enters ACC to be cooled for multiple times, the temperature of the intermediate billet is reduced to be below Tnr (non-recrystallization temperature), and the finishing temperature is controlled to be Ar3+10 ℃; after the finish rolling, the steel plate is cooled by the ACC again, and after the ACC is discharged, the temperature of the red returning of the steel plate is controlled to be 580-620 ℃; the quenching temperature is AC3+ (30-50) DEG C, namely 910-930 ℃, and the quenching time is set to be 1.8-2.4 min/mm; the sub-temperature quenching adopts AC3- (30-60) DEG C, namely 820-850 ℃, and the quenching time is set to be 1.8-2.2 min/mm; the high-temperature tempering temperature is 580-650 ℃, and the tempering time is set to be 3.0-6.0 min/mm.
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| CN111621708A (en) * | 2020-06-30 | 2020-09-04 | 南阳汉冶特钢有限公司 | Novel steel plate with impact toughness higher than P690QL2 steel plate for LPG ship storage tank and production method thereof |
| CN111893269A (en) * | 2020-07-28 | 2020-11-06 | 西安建筑科技大学 | Method for making heat treatment process window of low-temperature pressure vessel steel |
| CN112941412A (en) * | 2021-01-30 | 2021-06-11 | 南阳汉冶特钢有限公司 | Production method of extra-thick 550 MPa-grade anti-seismic and weather-resistant steel |
| CN114875304A (en) * | 2022-03-31 | 2022-08-09 | 新余钢铁股份有限公司 | Quenched and tempered high-strength steel plate for SA537MCL2 pressure vessel and production method thereof |
| CN116815074A (en) * | 2023-06-07 | 2023-09-29 | 北京科技大学 | High-strength and high-toughness Q690F super-thick weather-resistant steel plate with excellent thickness uniformity and preparation method thereof |
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| CN111621708A (en) * | 2020-06-30 | 2020-09-04 | 南阳汉冶特钢有限公司 | Novel steel plate with impact toughness higher than P690QL2 steel plate for LPG ship storage tank and production method thereof |
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| CN111893269A (en) * | 2020-07-28 | 2020-11-06 | 西安建筑科技大学 | Method for making heat treatment process window of low-temperature pressure vessel steel |
| CN111893269B (en) * | 2020-07-28 | 2022-05-10 | 西安建筑科技大学 | Method for making heat treatment process window of low-temperature pressure vessel steel |
| CN112941412A (en) * | 2021-01-30 | 2021-06-11 | 南阳汉冶特钢有限公司 | Production method of extra-thick 550 MPa-grade anti-seismic and weather-resistant steel |
| CN114875304A (en) * | 2022-03-31 | 2022-08-09 | 新余钢铁股份有限公司 | Quenched and tempered high-strength steel plate for SA537MCL2 pressure vessel and production method thereof |
| CN116815074A (en) * | 2023-06-07 | 2023-09-29 | 北京科技大学 | High-strength and high-toughness Q690F super-thick weather-resistant steel plate with excellent thickness uniformity and preparation method thereof |
| CN116815074B (en) * | 2023-06-07 | 2024-02-09 | 北京科技大学 | High-strength and high-toughness Q690F super-thick weather-resistant steel plate with excellent thickness uniformity and preparation method thereof |
| CN117004885A (en) * | 2023-07-24 | 2023-11-07 | 鞍钢股份有限公司 | Ultralow-temperature high-strength container steel plate and manufacturing method thereof |
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Application publication date: 20200313 |