CN115216699A - Steel plate for normalizing Q460-grade pressure vessel and production method thereof - Google Patents

Steel plate for normalizing Q460-grade pressure vessel and production method thereof Download PDF

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CN115216699A
CN115216699A CN202210895703.XA CN202210895703A CN115216699A CN 115216699 A CN115216699 A CN 115216699A CN 202210895703 A CN202210895703 A CN 202210895703A CN 115216699 A CN115216699 A CN 115216699A
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steel
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龙渊
周文浩
刘丹
史术华
张青学
孙小平
李玉路
徐琛
杨小军
杜豪
刘晓玮
韩德川
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Hunan Valin Xiangtan Iron and Steel Co Ltd
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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
    • B22—CASTING; POWDER METALLURGY
    • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
    • B22D11/00—Continuous casting of metals, i.e. casting in indefinite lengths
    • B22D11/001—Continuous casting of metals, i.e. casting in indefinite lengths of specific alloys
    • 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
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    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
    • C21D1/26—Methods of annealing
    • C21D1/28—Normalising
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    • C21D6/00—Heat treatment of ferrous alloys
    • C21D6/001—Heat treatment of ferrous alloys containing Ni
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    • C21D6/00—Heat treatment of ferrous alloys
    • C21D6/005—Heat treatment of ferrous alloys containing Mn
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D6/00—Heat treatment of ferrous alloys
    • C21D6/008—Heat treatment of ferrous alloys containing Si
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    • 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
    • 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
    • C21D8/0221—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the working steps
    • C21D8/0226—Hot rolling
    • 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
    • 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
    • C22C38/06—Ferrous alloys, e.g. steel alloys containing aluminium
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/08—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
    • 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
    • C22C38/14—Ferrous alloys, e.g. steel alloys containing titanium or zirconium
    • 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
    • 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
    • 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
    • C21D2211/009—Pearlite
    • 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

A normalized Q460-grade pressure vessel steel plate and a production method thereof, the chemical components of the steel by mass percent are C = 0.16-0.20, si = 0.10-0.20, mn = 1.50-1.70, P ≤ 0.012, S ≤ 0.002, alt = 0.060-0.080, nb = 0.030-0.040, V = 0.10-0.12, ti =0.010-0.020, mo =0.04-0.06, ni =0.20-0.40, N =0.006-0.0010, ceq ≤ 0.51%, and the rest is Fe and residual elements; the adopted process route is as follows: converter smelting → LF refining → RH vacuum refining → continuous casting → slab heating → controlled rolling → heat treatment (normalizing + tempering). The steel structure of the invention is bainite, pearlite and ferrite, the mechanical property, the product surface and the processing quality are excellent, and the standard TI-grade flaw detection qualification rate of NB/T47013.3 is 100%.

Description

Steel plate for normalizing Q460-grade pressure vessel and production method thereof
Technical Field
The invention belongs to the technology of steel smelting, rolling and heat treatment, and particularly relates to normalized Q460 grade steel for a pressure container and a production method thereof.
Background
With the social development and the continuous progress of steel material technology, pressure vessels are in the development stages of high reinforcement, low temperature, light weight, energy conservation, environmental protection and other technologies. At present, the highest strength mark in Chinese national standard GB/T713-2014 is Q420R, but the yield lower limit value is 420MPa, the tensile strength is 590 to 700MPa, the impact toughness only meets the low-temperature environment at minus 20 ℃, and various mechanical property indexes are difficult to meet the design requirements of pressure containers of special media. The steel for the high-grade normalized Q460-grade pressure container with the yield strength of more than or equal to 460Mpa and the tensile strength of 630-720Mpa and the transverse impact at the low temperature of minus 40 ℃ of more than or equal to 60J has wide application prospect in the market.
CN107326273A discloses a steel plate for a low-temperature container with a vanadium-nitrogen series Q460 strength level and a production method thereof, wherein the steel has the advantages that although the mechanical property meets the requirement, the quality of a casting blank is affected due to the excessively high content of V and N, the production cost is high, and meanwhile, the manufacturing process comprises sub-temperature quenching and tempering. CN110846570A discloses 'a high-toughness Q460 grade high-strength steel plate and a manufacturing method thereof', the steel adopts quenching and tempering heat treatment, and the defects are that the quenching and tempering production period is long, the working procedure cost is high, and the quenching plate type is poor.
At present, Q460 strength grade steel is usually produced by adopting quenching and tempering and TMCP processes, but the steel plate produced by the method does not conform to the normalized or normalized plus tempered delivery state required by EN10028-3 standard.
Disclosure of Invention
The invention aims to provide a steel plate for a normalizing Q460-grade pressure container and a production method thereof, wherein the steel plate with the yield strength ReH of more than or equal to 460MPa, the tensile strength Rm of more than or equal to 630-720 MPa, the elongation A after fracture of more than or equal to 17 percent and the impact absorption energy KV of more than or equal to 60J is produced by the component design of micro-N and micro-Mo in combination with controlled rolling and a reasonable heat treatment process.
The technical scheme of the invention is as follows:
a normalizing Q460-grade pressure vessel steel plate adopts the following process route: converter smelting → LF refining → RH vacuum refining → continuous casting → slab heating → controlled rolling → heat treatment, the chemical composition mass percent of the steel is C = 0.16-0.20, si = 0.10-0.20, mn = 1.50-1.70, P ≤ 0.012, S ≤ 0.002, alt =0.060-0.080, nb =0.030-0.040, V =0.10-0.12, ti =0.010-0.020, mo =0.04-0.06, ni =0.20-0.40, N =0.006-0.0010, ceq ≤ 0.51%, and the rest is Fe and residual elements; the steel structure is uniform and fine bainite, ferrite and pearlite, and the grain size is 10.0 to 12.0 grades.
A production method of a steel plate for a normalized Q460-grade pressure container comprises key process steps.
(1) Converter steelmaking: the tapping C is more than or equal to 0.07 percent, and the P is less than or equal to 0.010 percent; carrying out slag raking operation after tapping;
(2) LF refining: the total argon blowing time of the molten steel in the LF furnace is more than or equal to 40min, and the white slag holding time is more than or equal to 20min; performing soft argon blowing operation before the molten steel is discharged from the LF, wherein the soft argon blowing time is more than 8min;
(3) RH refining: the total argon blowing time of the RH furnace in the station is more than or equal to 25min, and the holding time of the vacuum degree below 0.5tor is more than or equal to 12min. Blowing nitrogen in the RH furnace in the whole process, wherein the nitrogen flow is 110 to 130m3/h, the molten steel temperature is 1590 to 1610 ℃, and the argon soft blowing time is more than or equal to 12min after air breaking;
(4) Continuous casting: the section of the continuous casting is 260mm, the whole-process protective casting is carried out in the continuous casting, and the casting temperature is controlled according to the liquidus temperature plus (8-15 ℃);
(5) Heating the plate blank: heating the plate blank in a stepping furnace, and controlling the temperature to be 1200-1240 ℃;
(6) Controlling rolling: the initial rolling temperature of the first stage is 980-1150 ℃, the final rolling temperature is more than 950 ℃, and the secondary rolling rate of the last three stages is more than 20 percent; the initial rolling temperature of the second stage is 840 to 920 ℃, the single-pass reduction rate is more than 10 percent before rolling for 3 passes, and the final rolling temperature is 760 to 800 ℃;
(7) Normalizing: heating at 830-850 ℃ for 1.5-2.0 min/mm, wherein the plate thickness is mmX;
(8) Tempering: the heating temperature is 560 to 610 ℃, and the heat preservation time is mm x (2.5 to 3.5) min/mm of the plate thickness.
The invention relates to a chemical composition design principle of steel:
c: carbon often forms carbide with other alloy elements in steel, and plays a role in solid solution and precipitation strengthening. The carbon content should be maintained at a certain level in terms of securing the strength of the steel sheet and reducing the alloy cost, but the carbon content should be reduced in terms of improving the low-temperature toughness of the steel sheet. Therefore, in consideration of the alloy components and the performance requirements of the steel, the C content of the steel is controlled to be 0.16-0.20%.
Si: the steel plate has a solid solution strengthening effect, can improve the yield strength of the steel plate, but is not beneficial to rolling refinement because the low-temperature toughness is reduced along with the increase of the Si content, and the temperature of a non-recrystallization area is reduced. The Si of the steel is controlled within the range of 0.10 to 0.20 percent, which is favorable for the comprehensive performance.
Mn: is a solid solution strengthening element, can refine crystal grains, is beneficial to improving the strength and toughness of the steel plate, but is easy to generate segregation and form MnS inclusions.
P: the cold-brittle element is an easily segregated element which easily causes "cold brittleness" at the time of cold working, increases temper brittleness, and is very disadvantageous to the low-temperature toughness of steel. Therefore, the phosphorus content in the steel should be strictly controlled, and P in the steel of the present invention is controlled to be 0.012% or less.
S: improve machinability, cause hot shortness, deteriorate the quality of steel, and affect weldability. S in the steel is controlled within 0.002%.
Nb: it has strong affinity with nitrogen and carbon in steel, and can form stable Nb (C, N) compound with it. Nb (C, N) particles dispersed and distributed along austenite grain boundaries can greatly improve the coarsening temperature of original austenite grains, thereby refining ferrite grains and improving low-temperature toughness and strength.
V: has strong precipitation strengthening and fine grain strengthening effects, can improve the strength and toughness of steel, reduce overheating sensitivity and improve thermal stability. The V of the steel is controlled to be 0.10 to 0.12 percent.
N: promote the generation of precipitates such as AlN, nb (C, N), VN and the like, fully exert two strengthening modes of fine grain strengthening and precipitation strengthening, and improve the strength and toughness matching of the steel. However, the excessively high N content reduces the occurrence of cracks on the surface of a casting blank caused by the thermoplasticity of the steel, so that the N content of the steel is controlled to be 0.006 to 0.0010 percent.
Mo: promote the generation of medium-temperature transformation bainite structure, and obviously improve the strength of the steel through phase transformation strengthening. However, bainite formed in an air-cooled state generally has coarse grains and poor low-temperature toughness, so that the Mo element of the invention is strictly controlled within 0.04-0.06%, and the toughness of the steel plate is ensured mainly by controlling the bainite proportion.
The principle of the invention on process design: according to the chemical composition design of the steel, the production process parameters of each procedure are strictly controlled, 0.04 to 0.06 percent of trace Mo element is mainly added, the micro N control of 0.006 to 0.0010 percent in molten steel is ensured through LF refining and RH whole-course nitrogen blowing, meanwhile, the performance of the steel plate can meet the set requirement by adopting a controlled rolling and normalizing and tempering heat treatment process, the structure of the steel plate is bainite, pearlite and ferrite, and the grain size reaches 10.0 to 12.0 grade.
The invention has the beneficial effects that: a. the component design adopts a component system of micro nitrogen and micro Mo, and on the basis of adding Al, nb and V micro alloy elements in steel, by adding trace N elements, precipitates such as AlN, nb (C, N), VN and the like are formed to realize fine grain and precipitation strengthening, so that the toughness of steel is improved, and the occurrence of casting blank surface cracks caused by the thermoplasticity of the steel cannot be obviously reduced. The addition of the micro Mo promotes a small amount of structures to be transformed into bainite, so that the strength of the steel is obviously improved, the addition amount of V alloy is reduced, the manufacturing cost is reduced, the toughness of the steel plate is ensured through strict control of the bainite structure proportion, and the performance of the steel plate meets the technical requirements of Table 1; b. a reasonable plate blank heating process is designed, sufficient solid solution of microalloy elements is ensured through long-time high-temperature heating, the original austenite grain size is continuously refined through high-temperature high-pressure low-speed rolling and a low-temperature controlled rolling process in the II stage, and meanwhile, the strength and toughness of a steel plate are improved through mutagenic precipitation in the rolling process and precipitation after rolling; c. after normalizing and tempering the steel plate, the original rolled crystal grains do not grow, the structure is uniform and fine bainite, ferrite and pearlite, and the grain size reaches 10.0 to 12.0 grades; d. the low-temperature toughness, the welding performance and the like of the steel plate are further improved by strictly controlling harmful elements P and S and CE; e. a normalized Q460-grade pressure container produced by a normalizing and tempering process is a 6-20mm steel plate, the yield strength ReH is more than or equal to 460MPa, the tensile strength Rm is 630-720 MPa, the elongation A after fracture is more than or equal to 17%, the impact absorption energy KV2-40 ℃ is more than or equal to 60J, and the supply state meets the EN10028-3 standard requirement.
Drawings
FIG. 1 is a metallographic structure of the product of example 1.
FIG. 2 is a metallographic structure of the product of example 2.
Detailed Description
The present invention will be further described with reference to the following examples.
Example 1: production of steel for Q460 grade pressure container
The implementation process of the steel-making process comprises the following steps: tapping C =0.08% and P =0.009% from the converter, and slagging-off operation is carried out after tapping. The LF refining white slag is kept for 23min, and the outbound S =0.0018%; RH vacuum degree of 0.3tor, vacuum maintaining time of 12min and nitrogen flow of 120m 3 And/h, the incoming molten steel temperature of the RH furnace is 1604 ℃, and the outgoing molten steel temperature of the RH furnace is 1598 ℃. The soft argon blowing time is 14min, and the hydrogen is determined to be 1.4ppm. The thickness of a continuous casting section is 260mm, the superheat degree of molten steel of a continuous casting tundish is 8-13 ℃, and the smelting components are shown in Table 1.
The steel rolling process comprises the following implementation processes: the heating tapping temperature of the casting blank is 1224 ℃, the starting rolling temperature of the first stage is 1060 ℃, the reduction rates of the final three passes are respectively 20%,21% and 22%, the final rolling temperature is 992 ℃, and the thickness of the rolled intermediate blank is 80mm. The second stage is at the initial rolling temperature of 846 ℃, the final rolling temperature of 769 ℃, the reduction rates of the first three passes are respectively 12%, 11% and 11%, and the thickness of the rolled finished product is 20mm; and (3) normalizing process: keeping the temperature at 850 ℃ for 35min; and (3) tempering: the temperature is 590 ℃, and the temperature is kept for 60 min.
The product performance is shown in table 2, and the metallographic structure is shown in fig. 1.
Example 2: q460 grade steel for pressure vessel
The steel making process and the smelting chemical composition are the same as those in example 1.
The steel rolling process comprises the following implementation processes: the heating tapping temperature of the casting blank is 1215 ℃, the initial rolling temperature of the first stage is 1050 ℃, the reduction rates of the last three passes are respectively 20 percent, 22 percent and 24 percent, the final rolling temperature is 986 ℃, and the thickness of the rolled intermediate blank is 70mm. The initial rolling temperature of the second stage is 866 ℃, the final rolling temperature is 782 ℃, the reduction rates of the first three passes are 14%, 12% and 11% respectively, and the thickness of the rolled finished product is 12mm. And (3) normalizing process: keeping the temperature at 840 ℃ for 20min; and (3) tempering process: the temperature is 560 ℃, and the temperature is kept for 35 min.
The product performance is shown in table 2, and the metallographic structure is shown in fig. 2.
Example 3: q460 grade steel for pressure vessel
The steel making process and the smelting chemical composition are the same as those in example 1.
The steel rolling process comprises the following implementation processes: the heating tapping temperature of the casting blank is 1236 ℃, the rolling starting temperature of the first stage is 1070 ℃, the reduction rates of the last three passes are respectively 23 percent, 25 percent and 27 percent, the final rolling temperature is 1006 ℃, and the thickness of the rolled intermediate blank is 60mm. The second stage is at the initial rolling temperature of 916 ℃ and the final rolling temperature of 792 ℃, and the first three-pass reduction ratios are respectively as follows: 15 percent, 13 percent and 12 percent, and the thickness of the rolled finished product is 8mm. And (3) normalizing process: the temperature is 830 ℃, and the heat preservation time is 15min; and (3) tempering process: the temperature is 605 ℃, and the temperature is kept for 25 min.
The product properties are shown in table 2.
Table 1 example steel smelting chemistry (wt.%)
Figure 957952DEST_PATH_IMAGE001
。
TABLE 2 Performance test results of the steels of the examples
Figure 38647DEST_PATH_IMAGE002
。
As can be seen from table 1, the example compositions meet the design composition requirements. As can be seen from Table 2, after the steel of the invention is subjected to controlled rolling, normalizing and tempering, the steel plate has excellent strength and low-temperature toughness, completely meets the technical requirements of the invention purpose, and can be used for manufacturing pressure vessels.
As can be seen from fig. 1 and 2, the microstructure is fine bainite + pearlite + ferrite.

Claims (2)

1. A normalized Q460-grade pressure vessel steel plate is produced by the following process route: converter smelting → LF refining → RH vacuum refining → continuous casting → slab heating → controlled rolling → heat treatment, which is characterized in that: the chemical components of the steel by mass percent are C = 0.16-0.20, si =0.10-0.20, mn =1.50-1.70, P ≤ 0.012, S ≤ 0.002, alt =0.060-0.080, nb =0.030-0.040, V =0.10-0.12, ti =0.010-0.020, mo =0.04-0.06, ni =0.20-0.40, N =0.006-0.0010, ceq ≤ 0.51%, and the balance of Fe and residual elements; the steel structure is uniform and fine bainite, ferrite and pearlite, and the grain size is 10.0 to 12.0 grades.
2. A production method of a steel plate for a normalized Q460-grade pressure container is characterized by comprising the following key process steps:
(1) Converter steelmaking: the tapping C is more than or equal to 0.07 percent, and the P is less than or equal to 0.010 percent; carrying out slag skimming operation after tapping;
(2) LF refining: the total argon blowing time of the molten steel in the LF furnace is more than or equal to 40min, and the white slag holding time is more than or equal to 20min; carrying out soft argon blowing operation before the molten steel is discharged from the LF, wherein the soft argon blowing time is more than 8min;
(3) RH refining: the total argon blowing time of the RH furnace in the station is more than or equal to 25min, and the holding time of the vacuum degree below 0.5tor is more than or equal to 12min;
nitrogen is blown in the RH furnace in the whole process, the nitrogen flow is 110 to 130m < 3 >/h, the molten steel temperature is 1590 to 1610 ℃, and the argon soft blowing time after air breaking is more than or equal to 12min;
(4) Continuous casting: the section of the continuous casting is 260mm, the continuous casting is carried out with whole-process protection casting, and the casting temperature is controlled according to the liquidus temperature plus (8-15 ℃);
(5) Heating the plate blank: heating the plate blank in a stepping furnace, and controlling the temperature to be 1200-1240 ℃;
(6) Controlling rolling: the initial rolling temperature of the first stage is 980-1150 ℃, the final rolling temperature is more than 950 ℃, and the secondary rolling rate of the last three stages is more than 20 percent; the initial rolling temperature of the second stage is 840 to 920 ℃, the single-pass reduction rate is more than 10 percent before rolling for 3 passes, and the final rolling temperature is 760 to 800 ℃;
(7) Normalizing: heating at 830-850 ℃, and keeping the temperature for a time equal to the thickness of the plate mmX (1.5-2.0) min/mm;
(8) Tempering: the heating temperature is 560 to 610 ℃, and the heat preservation time is mm x (2.5 to 3.5) min/mm of the plate thickness.
CN202210895703.XA 2022-07-28 2022-07-28 Steel plate for normalizing Q460-grade pressure vessel and production method thereof Withdrawn CN115216699A (en)

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN116855834A (en) * 2023-07-22 2023-10-10 湖南华菱湘潭钢铁有限公司 Production method for reducing strip-shaped tissue grade of Q345D medium plate

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CN105369131A (en) * 2015-11-10 2016-03-02 湖南华菱湘潭钢铁有限公司 Production method of Q420R steel of steel board for pressure container
CN109161800A (en) * 2018-09-25 2019-01-08 湖南华菱湘潭钢铁有限公司 A kind of production method of the anti-SSCC liquefied gas truck tank tank body steel of low temperature
CN110438396A (en) * 2019-07-31 2019-11-12 江阴兴澄特种钢铁有限公司 The special thick container steel of a kind of low compression ratio, high-performance Q 345R ultra-wide and its manufacturing method
CN112981235A (en) * 2021-01-22 2021-06-18 江阴兴澄特种钢铁有限公司 Hardened and tempered steel plate with yield strength of 420MPa grade for building structure and production method thereof

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Publication number Priority date Publication date Assignee Title
CN105369131A (en) * 2015-11-10 2016-03-02 湖南华菱湘潭钢铁有限公司 Production method of Q420R steel of steel board for pressure container
CN109161800A (en) * 2018-09-25 2019-01-08 湖南华菱湘潭钢铁有限公司 A kind of production method of the anti-SSCC liquefied gas truck tank tank body steel of low temperature
CN110438396A (en) * 2019-07-31 2019-11-12 江阴兴澄特种钢铁有限公司 The special thick container steel of a kind of low compression ratio, high-performance Q 345R ultra-wide and its manufacturing method
CN112981235A (en) * 2021-01-22 2021-06-18 江阴兴澄特种钢铁有限公司 Hardened and tempered steel plate with yield strength of 420MPa grade for building structure and production method thereof

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN116855834A (en) * 2023-07-22 2023-10-10 湖南华菱湘潭钢铁有限公司 Production method for reducing strip-shaped tissue grade of Q345D medium plate

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