CN111926234B - Production method for producing super-thick high-strength steel plate for building with excellent thickness directivity based on continuous casting billet single frame - Google Patents
Production method for producing super-thick high-strength steel plate for building with excellent thickness directivity based on continuous casting billet single frame Download PDFInfo
- Publication number
- CN111926234B CN111926234B CN202010804046.4A CN202010804046A CN111926234B CN 111926234 B CN111926234 B CN 111926234B CN 202010804046 A CN202010804046 A CN 202010804046A CN 111926234 B CN111926234 B CN 111926234B
- Authority
- CN
- China
- Prior art keywords
- steel plate
- rolling
- less
- equal
- thickness
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Active
Links
Classifications
-
- 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
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
- C21D1/18—Hardening; Quenching with or without subsequent tempering
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D6/00—Heat treatment of ferrous alloys
- C21D6/005—Heat treatment of ferrous alloys containing Mn
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D6/00—Heat treatment of ferrous alloys
- C21D6/008—Heat treatment of ferrous alloys containing Si
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- 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
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D9/00—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
- C21D9/0081—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for slabs; for billets
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/001—Ferrous alloys, e.g. steel alloys containing N
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/002—Ferrous alloys, e.g. steel alloys containing In, Mg, or other elements not provided for in one single group C22C38/001 - C22C38/60
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/02—Ferrous alloys, e.g. steel alloys containing silicon
-
- 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
- C22C38/12—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
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/16—Ferrous alloys, e.g. steel alloys containing copper
Landscapes
- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Mechanical Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Physics & Mathematics (AREA)
- Thermal Sciences (AREA)
- Crystallography & Structural Chemistry (AREA)
- Heat Treatment Of Steel (AREA)
Abstract
The invention discloses a production method for producing an ultra-thick high-strength steel plate for a building with excellent thickness directivity based on a continuous casting billet single frame, wherein the steel plate is simple in component design, and cheap Ti, Cu and a proper amount of Nb alloy are mainly used as main strengthening alloy elements; the production method mainly controls the addition ratio of Si, Mn and Cu and the contents of harmful elements P, S and P + S in the steel plate through the smelting process, and reduces the internal gas content of the casting blank and the generation of defects such as inclusion, shrinkage cavity and the like; through controlled rolling, the coarse columnar crystal structure of a casting blank is crushed, crystal grains are refined, the fine and uniform structure in the thickness direction is ensured, and meanwhile, the strength is improved; by controlling heat treatment, the structure defect is further eliminated, the structure is improved, the components are homogenized, the crystal grains are refined, and the good thickness direction performance is obtained, and meanwhile, the strength is ensured to meet the requirement; the method has the advantages of low production cost, high product performance and high added value, improves the production efficiency and economic benefit, and has great popularization significance.
Description
Technical Field
The invention relates to the technical field of steel materials, in particular to a method for producing an ultra-thick high-strength steel plate for a building with excellent thickness directivity based on a continuous casting billet single frame.
Background
With the rapid development of national economy in China, the demand of various fields for thick steel plates is continuously increased, wherein high-rise buildings are particularly remarkable, and the thick steel plates are generally applied to key parts, so that extremely strict requirements are provided for the mechanical properties of the steel plates, particularly the properties in the thickness direction. In order to effectively transmit the rolling force to the core, improve the performance of the core and ensure the structural performance uniformity of the steel plate in the thickness direction, the rolling compression ratio is generally considered to be more than or equal to 3.0 so as to ensure the internal quality uniformity of the steel plate. In order to meet the requirement of the compression ratio, most steel mills producing ultra-thick steel plates adopt methods such as composite welding or ultra-large continuous casting to prepare mother blanks. However, these methods require enormous equipment costs, are expensive per ton of steel to produce, are inefficient, and are difficult to popularize and popularize. At present, the thickness of a continuous casting billet produced by a domestic medium plate factory is generally not more than 300mm, and in order to improve the core performance of a steel plate and improve the performance uniformity, a part of steel mills not only improve the production cost, but also reduce the welding performance of the steel plate by adding noble alloy elements such as Ni and the like. In addition, the steel mill generally adopts a rolling and normalizing heat treatment or quenching and tempering treatment mode when producing the steel plate, and the final required performance is achieved by sacrificing the strength or increasing the process flow, thereby further improving the production cost invisibly.
In China, the production of super-thick steel plates by continuous casting billets is reported mostly. For example, the application of Chinese patent application No. 201711310106.1 discloses a 160mm thick extra-thick plate produced under the condition of low compression ratio and a production method thereof, wherein a casting blank with the thickness of 320mm is adopted, and the chemical components are as follows: c: 0.14% -0.16%, Si: 0.15% -0.25%, Mn: 1.45% -1.55%, P: less than or equal to 0.015%, S: less than or equal to 0.0020 percent, Nb: 0.030-0.035%, V: 0.050% -0.055%, Ti: 0.010% -0.020%, Ni: 0.22-0.25%, Alt: 0.040% -0.060%. More precious alloy V and expensive alloy Ni are added, and the actual strength of the alloy can only reach the Q345 level and cannot meet the production of high-strength steel plates. The application with the Chinese patent application number of 201711310081.5 discloses a super-thick plate produced under the condition of low compression ratio and a production method thereof, wherein a Q390 steel plate with the thickness of 150mm, which is prepared by a continuous casting billet, is difficult to meet the requirement of higher strength level.
The application with the Chinese patent application number of 201811142900.4 discloses a Z-direction performance steel plate with the thickness of 150mm and the low compression ratio and a production method thereof, wherein the temperature difference between the upper surface layer and the lower surface layer of the steel plate and the center part is relatively large by using an inter-pass instant cooling technology in the rough rolling stage, so that the effect of differential temperature rolling is achieved. The production method needs a cooling device with a longer interval between rough rolling and finish rolling, and on the other hand, the equipment failure is easily caused by the torque overrun in the rolling process due to the larger temperature difference between the inner surface and the outer surface, so the method is not popularized.
Based on the above situation, the search for a steel plate with extra thick, higher strength and better thickness directional performance by adopting more economic component design without increasing equipment investment becomes a problem to be solved urgently in the industry at present, and will bring greater significance to the production of extra thick plates. Therefore, the development of the ultra-thick high-strength steel plate for the building, which has the advantages of low production cost, quick production rhythm, excellent mechanical property, structural property in the thickness direction and high uniformity, has great social benefit and economic benefit.
Disclosure of Invention
The invention aims to provide a method for producing an ultra-thick high-strength steel plate for a building with excellent thickness direction performance based on a continuous casting blank single frame, aiming at the defects in the prior art, the method adopts a 300mm thick casting blank, and adopts the single frame to produce the ultra-thick high-strength steel plate for the building structure with the tensile strength of more than or equal to 660MPa, the yield ratio of less than or equal to 0.73, the performance in the thickness direction of more than or equal to 45 percent and the finished product thickness of 100-150 mm under the condition of not modifying equipment.
The invention relates to a method for producing an ultra-thick high-strength steel plate for a building, which has excellent thickness directivity and is based on a continuous casting billet single frame, wherein the steel plate contains the following elements in percentage by weight:
c: 0.12-0.20%, Si: 0.3-0.55%, Mn: 1.20-1.50%, Ti: 0.012-0.025%, Nb: 0.030-0.045%, Cu: 0.2-0.4%, Als: 0.010-0.045%, total oxygen content less than or equal to 6ppm, N content less than or equal to 30ppm, H content less than 1.2ppm, P less than or equal to 0.007%, S less than or equal to 0.002%, and simultaneously: p and S are more than 0.0035 and less than 0.008 percent, and 83 percent of Si and 354 percent of N are more than 23 percent;
the production method of the steel plate comprises the steps of converter top and bottom composite smelting → inclusion calcium treatment → LF furnace refining → vacuum treatment → continuous casting → casting blank slow cooling → casting blank heating → rolling mill rolling → cooling → heat treatment → finishing, and is characterized in that:
(1) the converter is subjected to top-bottom composite smelting, the total oxygen content is less than or equal to 6ppm, the N content is less than or equal to 30ppm, the H content is less than 1.2ppm, the P content is less than or equal to 0.007%, the S content is less than or equal to 0.002%, the P + S content is strictly limited to be more than 0.0035 and less than 0.008%, the casting speed is controlled to be 0.68-0.75 m/min in the continuous casting process, the casting speed fluctuation is less than 0.02, and a casting blank with the thickness of 300mm is continuously;
(2) after the casting blank is off-line, stacking and cooling the casting blank in a field without air vents at the periphery for more than or equal to 72 hours, cleaning and checking the casting blank, and then sending the casting blank downwards;
(3) controlling the heating time of the casting blank to be 350-400 min, wherein the soaking time is more than or equal to 55 min; heating to 1210-1230 ℃;
(4) the rolling of the rolling mill adopts two-stage controlled rolling, the steel plate swings back and forth to 1150 ℃ before reaching the rolling mill to start rolling, the number of times of a longitudinal rolling channel is strictly controlled to be less than or equal to 4 in one stage, the single-pass rolling reduction of the longitudinal rolling is more than or equal to 32mm, and the rolling speed is 1.2-1.6 m/s; rolling until the thickness of the intermediate blank is heated, wherein the thickness of the intermediate blank is controlled according to the thickness h multiplied by 1.03+ (20-40) mm of a finished product, and the thickness h of the finished product is 100-150 mm; cooling the intermediate blank to 1030-1060 ℃, starting the machine and removing the scale once; starting a machine body to remove the scale water and back-and-forth casting for 2 times when the temperature of the steel plate is reduced to 900-950 ℃, and controlling the speed of a roller way to be 0.8-1.0 m/s; the initial rolling temperature of the second stage is 840-850 ℃, the number of rolling passes is 3-4, and the load temperature of the final rolling is 830-840 ℃;
(5) cooling by water after rolling, wherein the starting cooling temperature is controlled to be 760-820 ℃, the cooling speed is controlled to be 25-30 ℃/S, and the temperature of red returning is controlled to be 580-630 ℃;
(6) air cooling the cooling bed to 250-300 ℃, performing down-line slow cooling, covering the lower part of the steel plate by using a common steel plate with the temperature of 150-300 ℃ as a base plate, and covering the upper part of the steel plate by using a steel plate with the temperature of 150-300 ℃, wherein the height of the stacked steel plate is required to be in the range of 800-1000 mm, the thickness of the base plate or the covering plate is more than or equal to 200mm, and the cooling time of the pile is more than or;
(7) the steel plate is subjected to high-temperature tempering heat treatment, the tempering temperature is controlled according to 620-650 ℃, and the heat preservation time is 2.5 times of the thickness h of a finished product.
The thickness of the steel plate is 100-150 mm, the performance of the steel plate in the thickness direction is 45-64%, the yield strength is 480-510 MPa, the tensile strength is 669-700 MPa, the yield ratio is not more than 0.73, the elongation is 26-30.5%, and the impact energy at the temperature of minus 20 ℃ is 189-255J.
The function and control of each component in the invention have the following characteristics:
c: the carbon can greatly improve the strength of the steel and the wear resistance of the steel plate, and when the content of the C is less than 0.12 percent, the strengthening effect of the C is weakened, so that the strength of the steel is insufficient; when the C content is higher than 0.20%, the welding cold crack sensitivity coefficient is improved, the low-temperature toughness of the base material and a welding heat affected zone is reduced strongly, and the cold and hot processing performance is influenced, so that the C content is controlled to be 0.12-0.20%.
Si: the tempering stability of the silicon energy high steel ensures that the alloy has higher hardness and strength than carbon steel with the same carbon content when being tempered at the same temperature; or under the condition of ensuring the same strength, the steel can be tempered at higher temperature to obtain better toughness. Meanwhile, silicon is an essential element for steel-making deoxidation, and is an element for inhibiting ferrite solid solution strengthening and carbide formation to increase the stability of retained austenite and further increase the ductility of a steel plate, and has a certain strengthening effect. When the silicon content is less than 0.3%, the effect cannot be ensured. When the silicon content exceeds a certain amount, the cleanliness of the steel is reduced, and scale defects which are not easy to pickle are generated, so that the silicon content is controlled to be 0.3-0.55%.
Mn: the steel has good solid solution strengthening effect, the strength of the steel is improved within a certain range, cementite appearing in grain boundaries after slow cooling is reduced, so that the toughness of the steel is improved, but the content of Mn cannot be too high, otherwise, the reduction of martensite phase transformation points is influenced, so that the amount of residual austenite at room temperature is increased, and therefore, the content is controlled to be 1.20-1.60%.
Ti: titanium is a strong deoxidizer in steel, can make the internal structure of steel compact, refine crystal grains, reduce aging sensitivity and cold brittleness, improve welding performance, and can reduce the difference of longitudinal and transverse performances by adding a certain amount of Ti. In addition, compared with the strengthening elements such as niobium, vanadium and the like, titanium has larger resource and cost advantages, the price is less than one tenth of the price, so the Ti content is designed as follows: 0.012-0.025%;
cu: copper can improve the strength, fatigue resistance and impact toughness of the steel plate, improve the welding performance, formability, machinability and the like, can generate remarkable strengthening effect without depending on carbon and nitrogen elements, has more economical efficiency compared with other precious alloys, but is easy to generate hot brittleness when the content exceeds a certain range, so that the Cu content is controlled within the range of 0.2-0.4%.
11 < Mn +16Si +20Cu < 15: the strength of the steel can be obviously improved by Mn, Si and Cu, but the welding performance of the steel can be influenced by too high content, the plasticity can be reduced, the strength of the steel can be influenced by too low content, according to experience, the strength and toughness of the steel plate can meet the design requirements under the conditions that other conditions are met and the conditions that 11 is less than Mn +16Si +20Cu is less than 15 are met, and therefore, the condition that 11 is less than Mn +16Si +20Cu is less than 15 is further limited.
Nb: the metal niobium is a strong carbide forming element and has strong grain refining and precipitation strengthening effects, and fine carbonitride particles formed by Nb can effectively inhibit austenite grains from growing large in the rolling process and have a strong refining effect on the final structure of a product, so that the strength, the low-temperature toughness and the elongation performance are improved. Nb is controlled to be 0.030-0.045%
And Als: aluminum is used as a nitrogen deoxidizing and fixing agent in steel making, so that crystal grains are refined, the aging of low-carbon steel is inhibited, the toughness of the steel at low temperature is improved, and the oxidation resistance of the steel can be improved. Controlling Als to be 0.010-0.045%
P: the biggest harm of phosphorus is to cause serious segregation and influence the performance in the thickness direction and the flaw detection result, and meanwhile, the phosphorus element increases the tempering brittleness and the cold brittleness sensitivity, so that the welding performance of the steel is deteriorated, and the plasticity is reduced, therefore, the P content is designed to be less than or equal to 0.007%.
S: sulphur is also a harmful element in normal conditions, and is generally present in steel in the form of FeS, which is poor in plasticity and low in melting point. FeS is distributed around the grain boundary when the molten steel is crystallized. Heating and rolling at 800-1200 ℃ can cause cracking through grain boundaries. In addition, S often forms strip-like MnS inclusions with Mn in molten steel, and it has been found that when the MnS content in steel is high, the lower the diffusion coefficient of hydrogen in steel is, the lower the mechanical properties and internal quality are. Therefore, the S content is designed to be less than or equal to 0.002 percent.
Meanwhile, the strict limitation is that P + S is more than 0.0035 percent and less than 0.008 percent. Phosphorus and sulfur are generally used as harmful elements in steel, but trace phosphorus and sulfur can act with manganese in a combined way, so that the strength can be improved, the machinability of the steel and the surface quality of a machined part can be improved, and according to experience, the effect can be achieved only when the requirement that 0.0035% and P + S are less than 0.008% is met.
In the technical scheme of the invention, the reasons for controlling the principles and main process parameters of the smelting, rolling cooling and heat treatment processes are as follows:
(1) converter and refining are controlled according to the production of clean steel, the total oxygen content in molten steel is less than or equal to 6ppm, the nitrogen content is less than or equal to 30ppm, the hydrogen content is less than 1.2ppm, P is less than or equal to 0.007%, S is less than or equal to 0.002%, the content of P plus S is strictly limited to be more than 0.0035% and less than 0.008%, the pulling speed is controlled to be 0.68-0.75 m/min, the pulling speed fluctuation is less than 0.02, a casting blank with the thickness of 300mm is continuously cast, the superheat degree is controlled to be within the range of 10-15 ℃, the internal gas content of the casting blank is reduced through the control parameters, the generation of defects such as inclusion, shrinkage cavity and the like; meanwhile, the Mn +16Si +20Cu is strictly limited to be more than 11 and less than 15;
(2) after the casting blank is off-line, the casting blank is cooled in a windless field at the periphery for more than or equal to 72 hours, so that the diffusion of C, Mn elements in the steel is promoted to reduce segregation, and meanwhile, supersaturated hydrogen in the steel has sufficient time to overflow, the internal quality of the casting blank is improved, the possibility of defect generation is reduced, the internal defect risk of a produced steel plate is reduced, and the flaw detection qualification rate and the thickness direction performance are improved;
(3) controlling the heating time of the casting blank to be 350-400 min, wherein the soaking time is more than or equal to 55 min; heating to 1210-1230 ℃; ensuring that micro-alloy elements in the steel are dissolved into austenite, and simultaneously preventing austenite grains from coarsening;
(4) the rolling of the rolling mill adopts two-stage controlled rolling, the steel plate swings back and forth to 1150 ℃ before reaching the rolling mill to start rolling, the number of times of a longitudinal rolling pass is strictly controlled to be less than or equal to 4 in one stage, the single-pass reduction rate of the longitudinal rolling is more than or equal to 32mm, and the rolling speed is 1.2-1.6 m/s; rolling to the thickness of an intermediate blank to be heated, controlling the thickness of the intermediate blank according to the thickness h multiplied by 1.03+ (20-40) mm of a finished product, (the thickness h of the finished product is 100-150 mm), cooling the intermediate blank to 1030-1060 ℃, starting up the body to remove the scale water once, aiming at shortening the time of heating and improving the rhythm, starting up the body to remove the scale water to pour back and forth 2 times when the temperature is 900-950 ℃, improving the short-term hardness of the surface of the steel plate through water spraying so that the rolling force is effectively transmitted to the center, crushing coarse columnar crystal structures of a casting blank to refine crystal grains, ensuring that the structures in the thickness direction are fine and uniform, and improving the strength simultaneously; when the surface hardness is too high and the steel plate enters a rolling mill, the torque is easy to exceed the upper limit, so that equipment faults are easy to occur, the steel plate is set within a certain temperature range before the two-stage rolling, the steel plate is slightly red, and the speed of a roller way is controlled to be 0.8-1.0 m/s; the initial rolling temperature of the second stage is 840-850 ℃, the number of rolling passes is 3-4, and the load temperature of the final rolling is 830-840 ℃;
(5) cooling after rolling is adopted, wherein the starting cooling temperature is controlled to be 760-820 ℃, the cooling speed is controlled to be 25-30 ℃/S, and the temperature of red returning is controlled to be 580-630 ℃, so that crystal grains are further refined, and the strength of the steel plate is improved;
(6) the steel plate is cooled from the air of a cooling bed to 250-300 ℃ and then is stacked and slowly cooled, a common steel plate with the temperature of 150-300 ℃ is used as a base plate below the steel plate, a steel plate with the temperature of 150-300 ℃ is used for covering the upper part of the steel plate, the height of the stacked steel plate is required to be within the range of 800-1000 mm, the thickness of the base plate or the covering plate is more than or equal to 200mm, and the stacking and cooling time is more than or equal to; the method can prevent poor internal quality of the steel plate caused by insufficient release of gaseous hydrogen, and simultaneously avoid defect detection and poor performance in the thickness direction caused by expansion of internal microcracks due to insufficient release of large internal stress;
(7) the steel plate is subjected to high-temperature tempering heat treatment, the tempering temperature is controlled according to 620-650 ℃, and the heat preservation time is 2.5 times the thickness h of the finished product; further eliminating the defects of the structure, refining the crystal grains, improving the structure, homogenizing the components, refining the crystal grains to obtain good performance in the thickness direction and simultaneously ensuring that the strength meets the requirements.
According to the technical scheme provided by the invention, medium-low carbon is adopted in steel components, cheap Ti, Cu and a proper amount of Nb alloy are used as main strengthening alloy elements, the addition ratio of Si, Mn and Cu is limited, and the content of harmful elements P, S and P + S is strictly controlled; through controlled rolling, the coarse columnar crystal structure of a casting blank is crushed, crystal grains are refined, the fine and uniform structure in the thickness direction is ensured, and meanwhile, the strength is improved; by controlling the heat treatment, the structure defect is further eliminated, the structure is improved, the components are homogenized, the crystal grains are refined, and the good thickness direction performance is obtained, and meanwhile, the strength is ensured to meet the requirement.
The production method of the super-thick high-strength construction steel with excellent thickness directivity based on the continuous casting billet single-frame production has the following beneficial effects:
(1) the steel plate has simple chemical components, the production process is easy to operate, and complex procedures such as composite welding and the like are not needed;
(2) compared with the production of steel plates with other thick specifications, the method does not need to forcibly require the compression ratio to be more than or equal to 3:1, the casting blank can meet the thickness of 300mm, the production of over 95 percent of medium and heavy plate production lines in China is met, the method has general popularization significance, and the method belongs to high value-added products;
(3) the steel plate with super-thickness, high strength and excellent thickness directional performance can be produced by adopting a low-cost component design system, continuously casting to form a blank and rolling by a single frame without major reconstruction of the existing production equipment, so that the production efficiency and the economic benefit are improved, and the method has great popularization significance.
Detailed Description
In order to better explain the technical solution of the present invention, the technical solution of the present invention is further described below with reference to specific examples, which are only exemplary to illustrate the technical solution of the present invention and do not limit the present invention in any way.
The following table 1 is a list of chemical components contained in steel plates according to examples and comparative examples of the present invention in percentage by mass;
tables 2 and 3 below are lists of values of main process parameters of each example and comparative example of the present invention;
table 4 below is a table showing the results of performance tests of the steel sheets manufactured according to the examples of the present invention and the comparative examples.
The invention discloses a production method of an ultra-thick high-strength building steel plate with excellent thickness directivity based on a continuous casting billet single frame, which comprises the following elements in percentage by weight:
c: 0.12-0.20%, Si: 0.3-0.55%, Mn: 1.20-1.50%, Ti: 0.012-0.025%, Nb: 0.030-0.045%, Cu: 0.2-0.4%, Als: 0.010-0.045%, total oxygen content less than or equal to 6ppm, N content less than or equal to 30ppm, H content less than 1.2ppm, P less than or equal to 0.007%, S less than or equal to 0.002%, and simultaneously: p and S are more than 0.0035 and less than 0.008 percent, and 83 percent of Si and 354 percent of N are more than 23 percent;
the production method of the steel plate comprises the steps of converter top and bottom composite smelting → inclusion calcium treatment → LF furnace refining → vacuum treatment → continuous casting → casting blank slow cooling → casting blank heating → rolling mill rolling → cooling → heat treatment → finishing, and is characterized in that:
(1) the converter is subjected to top-bottom composite smelting, the total oxygen content is less than or equal to 6ppm, the N content is less than or equal to 30ppm, the H content is less than 1.2ppm, the P content is less than or equal to 0.007%, the S content is less than or equal to 0.002%, the P + S content is strictly limited to be more than 0.0035 and less than 0.008%, the casting speed is controlled to be 0.68-0.75 m/min in the continuous casting process, the casting speed fluctuation is less than 0.02, and a casting blank with the thickness of 300mm is continuously;
(2) after the casting blank is off-line, stacking and cooling the casting blank in a field without air vents at the periphery for more than or equal to 72 hours, cleaning and checking the casting blank, and then sending the casting blank downwards;
(3) controlling the heating time of the casting blank to be 350-400 min, wherein the soaking time is more than or equal to 55 min; heating to 1210-1230 ℃;
(4) the rolling of the rolling mill adopts two-stage controlled rolling, the steel plate swings back and forth to 1150 ℃ before reaching the rolling mill to start rolling, the number of times of a longitudinal rolling channel is strictly controlled to be less than or equal to 4 in one stage, the single-pass rolling reduction of the longitudinal rolling is more than or equal to 32mm, and the rolling speed is 1.2-1.6 m/s; rolling until the thickness of the intermediate blank is heated, wherein the thickness of the intermediate blank is controlled according to the thickness h multiplied by 1.03+ (20-40) mm of a finished product, and the thickness h of the finished product is 100-150 mm; cooling the intermediate blank to 1030-1060 ℃, starting the machine and removing the scale once; starting a machine body to remove the scale water and back-and-forth casting for 2 times when the temperature of the steel plate is reduced to 900-950 ℃, and controlling the speed of a roller way to be 0.8-1.0 m/s; the initial rolling temperature of the second stage is 840-850 ℃, the number of rolling passes is 3-4, and the load temperature of the final rolling is 830-840 ℃;
(5) cooling by water after rolling, wherein the starting cooling temperature is controlled to be 760-820 ℃, the cooling speed is controlled to be 25-30 ℃/S, and the temperature of red returning is controlled to be 580-630 ℃;
(6) air cooling the cooling bed to 250-300 ℃, performing down-line slow cooling, covering the lower part of the steel plate by using a common steel plate with the temperature of 150-300 ℃ as a base plate, and covering the upper part of the steel plate by using a steel plate with the temperature of 150-300 ℃, wherein the height of the stacked steel plate is required to be in the range of 800-1000 mm, the thickness of the base plate or the covering plate is more than or equal to 200mm, and the cooling time of the pile is more than or;
(7) the steel plate is subjected to high-temperature tempering heat treatment, the tempering temperature is controlled according to 620-650 ℃, and the heat preservation time is 2.5 times of the thickness h of a finished product.
The steel plate for the super-thick high-strength building, which is manufactured by adopting the element component contents and the processing steps, has the thickness of 100-150 mm, the performance of the steel plate in the thickness direction of 45-64%, the yield strength of 480-510 MPa, the tensile strength of 669-700 MPa, the yield ratio of less than or equal to 0.73, the elongation of 26-30.5% and the impact power of 189-255J at-20 ℃.
TABLE 1 steelmaking Process and chemical composition Table (wt%) for inventive and comparative examples
TABLE 2 Key procedure List for inventive and comparative examples
TABLE 3 List of the Process parameters for the inventive examples and comparative examples
TABLE 4 quality of the inventive and comparative examples
As can be seen from the above table 4, the steel plate with the thickness of 100-150 mm produced by adopting the components and the production process provided by the invention has the properties of 45-64% in the thickness direction, the yield strength of 480-510 MPa, the tensile strength of 669-700 MPa, the yield ratio of not more than 0.73, the elongation of 26-30.5% and the impact power of 189-255J at-20 ℃. The ultrasonic detection meets the special level requirement.
In contrast to comparative examples 1 and 2, the performance in the thickness direction is only 9-25%, the strength can only meet 345-level, and the flaw detection is unqualified for the second level.
The data in tables 1 to 4 show that the method can be used for producing the steel plate for the building structure, which has the thickness specification of 100-150 mm and the thickness direction performance of 45-64% and meets the requirements of special flaw detection and has the tensile strength of 660MPa, by adopting a single-stand rolling mill for a continuous casting billet with the thickness of 300 mm.
The above description is only a preferred embodiment of the present invention, and not intended to limit the scope of the present invention, and all modifications and equivalents of the present invention, which are made by the present specification and directly/indirectly applied to other related technical fields within the spirit of the present invention are included in the scope of the present invention.
Claims (2)
1. A production method for producing an ultra-thick high-strength steel plate for a building with excellent thickness directivity based on a continuous casting billet single frame is characterized in that the steel plate consists of the following elements in percentage by weight: c: 0.12-0.20%, Si: 0.3-0.55%, Mn: 1.20-1.50%, Ti: 0.012-0.025%, Nb: 0.030-0.045%, Cu: 0.2-0.4%, Als: 0.010-0.045%, total oxygen content less than or equal to 6ppm, N content less than or equal to 30ppm, H content less than 1.2ppm, P less than or equal to 0.007%, S less than or equal to 0.002%, and simultaneously: p and S are more than 0.0035 and less than 0.008 percent, 83 percent of Si and 354 percent of N are more than 23, Mn, 16Si and 20Cu are more than 11 and less than 15, and the balance is Fe and inevitable impurities;
the production method of the steel plate comprises the steps of converter top and bottom composite smelting → inclusion calcium treatment → LF furnace refining → vacuum treatment → continuous casting → casting blank slow cooling → casting blank heating → rolling mill rolling → cooling → heat treatment → finishing, and is characterized in that:
(1) the converter is subjected to top-bottom composite smelting, the total oxygen content is less than or equal to 6ppm, the N content is less than or equal to 30ppm, the H content is less than 1.2ppm, the P content is less than or equal to 0.007%, the S content is less than or equal to 0.002%, the P + S content is strictly limited to be more than 0.0035 and less than 0.008%, the casting speed is controlled to be 0.68-0.75 m/min in the continuous casting process, the casting speed fluctuation is less than 0.02, and a casting blank with the thickness of 300mm is continuously;
(2) after the casting blank is off-line, stacking and cooling the casting blank in a field without air vents at the periphery for more than or equal to 72 hours, cleaning and checking the casting blank, and then sending the casting blank downwards;
(3) controlling the heating time of the casting blank to be 350-400 min, wherein the soaking time is more than or equal to 55 min; heating to 1210-1230 ℃;
(4) the rolling of the rolling mill adopts two-stage controlled rolling, the steel plate swings back and forth to 1150 ℃ before reaching the rolling mill to start rolling, the number of times of a longitudinal rolling channel is strictly controlled to be less than or equal to 4 in one stage, the single-pass rolling reduction of the longitudinal rolling is more than or equal to 32mm, and the rolling speed is 1.2-1.6 m/s; rolling until the thickness of the intermediate blank is heated, wherein the thickness of the intermediate blank is controlled according to the thickness h multiplied by 1.03+ (20-40) mm of a finished product, and the thickness h of the finished product is 100-150 mm; cooling the intermediate blank to 1030-1060 ℃, starting the machine and removing the scale once; starting a machine body to remove the scale water and back-and-forth casting for 2 times when the temperature of the steel plate is reduced to 900-950 ℃, and controlling the speed of a roller way to be 0.8-1.0 m/s; the initial rolling temperature of the second stage is 840-850 ℃, the number of rolling passes is 3-4, and the load temperature of the final rolling is 830-840 ℃;
(5) cooling by water after rolling, wherein the starting cooling temperature is controlled to be 760-820 ℃, the cooling speed is controlled to be 25-30 ℃/s, and the temperature of red returning is controlled to be 580-630 ℃;
(6) air cooling the cooling bed to 250-300 ℃, performing down-line slow cooling, covering the lower part of the steel plate by using a common steel plate with the temperature of 150-300 ℃ as a base plate, and covering the upper part of the steel plate by using a steel plate with the temperature of 150-300 ℃, wherein the height of the stacked steel plate is required to be in the range of 800-1000 mm, the thickness of the base plate or the covering plate is more than or equal to 200mm, and the cooling time of the pile is more than or;
(7) the steel plate is subjected to high-temperature tempering heat treatment, the tempering temperature is controlled according to 620-650 ℃, and the heat preservation time is 2.5 times of the thickness h of a finished product.
2. The production method of the steel plate for the super-thick high-strength building with excellent thickness directional performance based on the continuous casting billet single frame as claimed in claim 1, is characterized in that: the thickness of the steel plate is 100-150 mm, the thick tensile section shrinkage rate of the steel plate is 45-64%, the yield strength is 480-510 MPa, the tensile strength is 669-700 MPa, the yield ratio is not more than 0.73, the elongation is 26-30.5%, and the impact energy at minus 20 ℃ is 189-255J.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202010804046.4A CN111926234B (en) | 2020-08-12 | 2020-08-12 | Production method for producing super-thick high-strength steel plate for building with excellent thickness directivity based on continuous casting billet single frame |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202010804046.4A CN111926234B (en) | 2020-08-12 | 2020-08-12 | Production method for producing super-thick high-strength steel plate for building with excellent thickness directivity based on continuous casting billet single frame |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN111926234A CN111926234A (en) | 2020-11-13 |
| CN111926234B true CN111926234B (en) | 2021-06-22 |
Family
ID=73312166
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202010804046.4A Active CN111926234B (en) | 2020-08-12 | 2020-08-12 | Production method for producing super-thick high-strength steel plate for building with excellent thickness directivity based on continuous casting billet single frame |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN111926234B (en) |
Families Citing this family (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113249642B (en) * | 2021-03-22 | 2023-03-07 | 江阴兴澄特种钢铁有限公司 | Large-thickness SA299GrB steel plate for steam drum end socket and manufacturing method thereof |
| CN113862425B (en) * | 2021-09-16 | 2022-10-14 | 湖南华菱湘潭钢铁有限公司 | Production process for improving flaw detection qualification rate of DQ steel plate |
| CN115679202A (en) * | 2022-06-27 | 2023-02-03 | 宝武集团鄂城钢铁有限公司 | Super-thick steel plate without heat treatment and with excellent Z-directional performance and production method thereof |
| CN115094331B (en) * | 2022-07-18 | 2023-05-09 | 柳州钢铁股份有限公司 | Low-cost Q690 steel plate and production method thereof |
Citations (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102061424A (en) * | 2010-12-21 | 2011-05-18 | 南阳汉冶特钢有限公司 | Super-thick Q390GJC-Z35 steel plate for high-rise buildings and production method thereof |
| CN103397251A (en) * | 2013-08-05 | 2013-11-20 | 武汉钢铁(集团)公司 | 150-190 mm thick bridge steel produced by continuous casting slab and technology thereof |
| CN105755369A (en) * | 2016-04-28 | 2016-07-13 | 江阴兴澄特种钢铁有限公司 | Easy-to-weld and low-temperature steel plate with excellent lamellar tearing resistance and manufacturing method thereof |
| CN105908086A (en) * | 2016-06-30 | 2016-08-31 | 江阴兴澄特种钢铁有限公司 | Extremely-thick low-alloy steel plate with low compression ratio and preparation method thereof |
| CN106319380A (en) * | 2015-06-16 | 2017-01-11 | 鞍钢股份有限公司 | Low compression ratio 690MPa grade extra thick steel plate and production method thereof |
| CN108914005A (en) * | 2018-08-10 | 2018-11-30 | 武汉钢铁集团鄂城钢铁有限责任公司 | A kind of the spy's thickness anti-corrosion steel plate and its production method of the excellent in low temperature toughness of yield strength > 460MPa |
| CN110306117A (en) * | 2019-08-02 | 2019-10-08 | 武汉钢铁集团鄂城钢铁有限责任公司 | A kind of high uniformity super thick structural steel plate and its manufacturing method |
| CN110343967A (en) * | 2019-08-02 | 2019-10-18 | 武汉钢铁集团鄂城钢铁有限责任公司 | A kind of uniform steel plate of normalizing rolling acquisition longitudinal direction performance and its manufacturing method |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS61136624A (en) * | 1984-12-08 | 1986-06-24 | Nippon Steel Corp | Manufacture of high toughness steel material having thick section and yield point of 42-<90kgf/mm2 |
-
2020
- 2020-08-12 CN CN202010804046.4A patent/CN111926234B/en active Active
Patent Citations (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102061424A (en) * | 2010-12-21 | 2011-05-18 | 南阳汉冶特钢有限公司 | Super-thick Q390GJC-Z35 steel plate for high-rise buildings and production method thereof |
| CN103397251A (en) * | 2013-08-05 | 2013-11-20 | 武汉钢铁(集团)公司 | 150-190 mm thick bridge steel produced by continuous casting slab and technology thereof |
| CN106319380A (en) * | 2015-06-16 | 2017-01-11 | 鞍钢股份有限公司 | Low compression ratio 690MPa grade extra thick steel plate and production method thereof |
| CN105755369A (en) * | 2016-04-28 | 2016-07-13 | 江阴兴澄特种钢铁有限公司 | Easy-to-weld and low-temperature steel plate with excellent lamellar tearing resistance and manufacturing method thereof |
| CN105908086A (en) * | 2016-06-30 | 2016-08-31 | 江阴兴澄特种钢铁有限公司 | Extremely-thick low-alloy steel plate with low compression ratio and preparation method thereof |
| CN108914005A (en) * | 2018-08-10 | 2018-11-30 | 武汉钢铁集团鄂城钢铁有限责任公司 | A kind of the spy's thickness anti-corrosion steel plate and its production method of the excellent in low temperature toughness of yield strength > 460MPa |
| CN110306117A (en) * | 2019-08-02 | 2019-10-08 | 武汉钢铁集团鄂城钢铁有限责任公司 | A kind of high uniformity super thick structural steel plate and its manufacturing method |
| CN110343967A (en) * | 2019-08-02 | 2019-10-18 | 武汉钢铁集团鄂城钢铁有限责任公司 | A kind of uniform steel plate of normalizing rolling acquisition longitudinal direction performance and its manufacturing method |
Also Published As
| Publication number | Publication date |
|---|---|
| CN111926234A (en) | 2020-11-13 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN111926234B (en) | Production method for producing super-thick high-strength steel plate for building with excellent thickness directivity based on continuous casting billet single frame | |
| CN110295320B (en) | Large-wall-thickness X52MS acid-resistant pipeline steel plate produced by LF-RH refining process and manufacturing method thereof | |
| CN108642381B (en) | Hot-rolled high-toughness low-temperature-resistant H-shaped steel with yield strength of 460MPa and preparation method thereof | |
| CN111876691A (en) | Super-thick high-toughness weather-resistant bridge steel plate and production method thereof | |
| CN111455269A (en) | Yield strength 960MPa grade very high strength marine steel plate and manufacturing method thereof | |
| CN114369764B (en) | High-performance thick hot-rolled H-shaped steel with yield strength of 460MPa and production method thereof | |
| CN113234995A (en) | Ultra-thick hot-rolled H-shaped steel with yield strength of 600MPa and production method thereof | |
| CN112226673A (en) | Hot rolled steel plate with 650 MPa-grade tensile strength and manufacturing method thereof | |
| CN110106445B (en) | High-strength high-low-temperature-toughness steel for ocean platform casting node and preparation method thereof | |
| CN113846269B (en) | Cold-rolled high-weather-resistance steel plate with high strength and plasticity and preparation method thereof | |
| CN114058974B (en) | 15.9-grade corrosion-resistant high-strength bolt steel and production method and heat treatment method thereof | |
| CN115181911A (en) | Super-thick Q500qE bridge steel plate and production method thereof | |
| CN110184530B (en) | Normalized steel sheet for pipe used under low temperature and acidic conditions and method for producing same | |
| CN114807751B (en) | A516Gr.70 (HIC) acid-resistant pipe steel with excellent die-welding and low-temperature performances and manufacturing method thereof | |
| CN112375997B (en) | Manufacturing method of X70M pipeline steel plate used under low-cost and ultralow-temperature conditions | |
| CN114941100A (en) | 130-plus-155 extra-thick low-carbon equivalent F-level high-strength steel plate for offshore wind power and manufacturing method thereof | |
| CN115074639A (en) | Hot-rolled steel plate for automobile beam with tensile strength of 600MPa | |
| CN113755759A (en) | Thick-specification high-toughness low-alloy high-strength structural steel and production method thereof | |
| CN111778450A (en) | Medium-manganese medium-thickness steel for 800MPa engineering machinery and manufacturing method thereof | |
| CN112593155B (en) | Anti-seismic, fire-resistant and weather-resistant steel plate for high-strength building structure and preparation method thereof | |
| CN115786806B (en) | High-strength low-carbon equivalent extra-thick steel plate with good low-temperature toughness and manufacturing method thereof | |
| CN114134414B (en) | Low-yield-ratio high-toughness steel and preparation method thereof | |
| CN114134405B (en) | Acicular ferrite/massive ferrite steel plate for ship and manufacturing method thereof | |
| CN115369328B (en) | Low-temperature-resistant rolled steel and production method thereof | |
| JP2543282B2 (en) | Method for producing controlled rolled steel with excellent toughness |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| GR01 | Patent grant | ||
| GR01 | Patent grant |