CN115094346B - Hot rolled strip steel with tensile strength more than or equal to 1200MPa and produced by adopting TSR production line and method - Google Patents
Hot rolled strip steel with tensile strength more than or equal to 1200MPa and produced by adopting TSR production line and method 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
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/38—Ferrous alloys, e.g. steel alloys containing chromium with more than 1.5% by weight of manganese
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21B—ROLLING OF METAL
- B21B1/00—Metal-rolling methods or mills for making semi-finished products of solid or profiled cross-section; Sequence of operations in milling trains; Layout of rolling-mill plant, e.g. grouping of stands; Succession of passes or of sectional pass alternations
- B21B1/46—Metal-rolling methods or mills for making semi-finished products of solid or profiled cross-section; Sequence of operations in milling trains; Layout of rolling-mill plant, e.g. grouping of stands; Succession of passes or of sectional pass alternations for rolling metal immediately subsequent to continuous casting
- B21B1/463—Metal-rolling methods or mills for making semi-finished products of solid or profiled cross-section; Sequence of operations in milling trains; Layout of rolling-mill plant, e.g. grouping of stands; Succession of passes or of sectional pass alternations for rolling metal immediately subsequent to continuous casting in a continuous process, i.e. the cast not being cut before rolling
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21B—ROLLING OF METAL
- B21B37/00—Control devices or methods specially adapted for metal-rolling mills or the work produced thereby
- B21B37/58—Roll-force control; Roll-gap control
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21B—ROLLING OF METAL
- B21B37/00—Control devices or methods specially adapted for metal-rolling mills or the work produced thereby
- B21B37/74—Temperature control, e.g. by cooling or heating the rolls or the product
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- 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
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- 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
- B22D11/06—Continuous casting of metals, i.e. casting in indefinite lengths into moulds with travelling walls, e.g. with rolls, plates, belts, caterpillars
- B22D11/0622—Continuous casting of metals, i.e. casting in indefinite lengths into moulds with travelling walls, e.g. with rolls, plates, belts, caterpillars formed by two casting wheels
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- 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
- B22D11/16—Controlling or regulating processes or operations
- B22D11/18—Controlling or regulating processes or operations for pouring
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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
- C21D11/00—Process control or regulation for heat treatments
- C21D11/005—Process control or regulation for heat treatments for cooling
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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
- C21D8/0221—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
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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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- 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
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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
- C22C38/001—Ferrous alloys, e.g. steel alloys containing N
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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
- C22C38/06—Ferrous alloys, e.g. steel alloys containing aluminium
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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
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/24—Ferrous alloys, e.g. steel alloys containing chromium with vanadium
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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
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/26—Ferrous alloys, e.g. steel alloys containing chromium with niobium or tantalum
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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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- 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
- C21D2211/008—Martensite
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Abstract
The hot rolled thin strip steel with the tensile strength more than or equal to 1200MPa grade produced by adopting a TSR production line comprises the following components in percentage by weight: c:0.12 to 0.20 percent, mn:1.8 to 3.0 percent, P is less than or equal to 0.01 percent, S is less than or equal to 0.01 percent, als:0.015 to 0.050 percent, cr is not more than 1.0 percent, N is not more than 0.005 percent, nb:0.01 to 0.05 percent or V: 0.06-0.20% of one or two of the components are added in a compounding way; the production method comprises the following steps: conventional smelting and refining; pouring into a blank; hot rolling; cooling; naturally cooling to room temperature after coiling; and (5) cold forming after unreeling and blanking. The invention not only ensures the mechanical property of the strip steel, but also can reduce the repeated heating, multiple dephosphorization, multipass rolling and the like of the strip steel by adding Nb or V or compounding the Nb and V and adopting TSR short-flow process production, and can cancel cold rolling and heat treatment, reduce the energy consumption by more than 80 percent and reduce the carbon dioxide emission by more than 70 percent, so that the surface roughness of the product is reduced from 1.5-3 mu m to less than 1 mu m, and a user does not need to acid wash before molding.
Description
Technical Field
The invention relates to a steel and a manufacturing method thereof, and particularly belongs to hot rolled thin strip steel with the tensile strength of more than or equal to 1200MPa and the method which are produced by adopting a double-roll thin strip casting and rolling (TSR) production line and have the tensile strength of more than or equal to 1200.5-2.0 mm.
Background
Light weight is an important way to realize the green low carbon development of the automobile industry. The advanced high-strength steel and the ultra-high-strength steel are adopted for the lightweight design and manufacture of the car body safety structural member, so that the collision safety of the whole car can be improved, the oil consumption or the energy consumption can be reduced, and the car body safety structural member is favored by automobile companies at home and abroad. The martensitic steel belongs to ultra-high strength steel and can be directly used for parts such as automobile anti-collision beams, threshold, carriages and the like; in recent years, steel companies at home and abroad start development work of ultra-high strength martensitic steel based on respective production lines.
Typical martensitic steel sheet has a tensile strength in the range of 1000 to 1800MPa and is produced by the following process route: molten steel smelting, continuous casting, cooling, casting blank heating, hot continuous rolling, cooling, coiling, uncoiling, pickling, cold rolling, coiling, uncoiling, heating, annealing, cooling and coiling. Such as the documents of Chinese patent publication No. CN 109898018A, CN 114086071A and CN 111519109B. In the production route, the raw materials need to be repeatedly coiled and uncoiled, heated and cooled, hot rolled and cold rolled, and the like, and the production route has the characteristics of complex process flow, long production period and high energy consumption, so that the production and manufacturing cost of the materials is greatly increased. Currently, the development of ultra-high strength steel sheets with low energy consumption, low cost and high quality is an important research direction of iron and steel companies.
The near net shape steel production technology eliminates the cold rolling and annealing heat treatment procedures of the traditional sheet, directly replaces the traditional cold-rolled sheet with the hot-rolled sheet of sheet billet continuous casting and rolling or sheet strip continuous casting and rolling, has the remarkable advantages of simple process flow, consumption reduction, energy saving and low production cost, and causes wide attention in the industry. However, due to the technical characteristics of the rapid solidification process, the tissue uniformity of the produced thin strip steel is easily affected by the design of the material composition; meanwhile, as the thin slab or the thin strip is adopted for continuous casting and rolling production, the total rolling reduction of the thickness of the material is far smaller than that of the traditional process, and the fine grain strengthening effect of the structure is greatly different from that of the traditional process. Therefore, the ultra-high strength automobile sheet steel produced by adopting the near net shape technology cannot simply and directly adopt the traditional product technology, and innovation and breakthrough are required in component design and production process. As disclosed in Chinese patent publication No. CN 106381451B, a hot rolled martensitic steel of 1000MPa grade is produced by a CSP sheet billet continuous casting and rolling process and a production method thereof, but the martensitic steel has lower tensile strength (only 1000 MPa). Chinese patent publication No. CN 112522571A discloses a method for producing martensitic steel strip by continuous casting of thin strip, but it requires rapid cooling (cooling rate is >120 ℃/s) of hot rolled steel strip, and the actual production difficulty is high and the uniformity of product performance is difficult to ensure. Aiming at the problems in the prior art, a novel low-cost 1200MPa grade ultra-high strength martensitic steel near-net-shape manufacturing method is researched and designed, so that the problems in the prior art are overcome.
Disclosure of Invention
The invention aims to overcome the defects of complex process, high energy consumption and large fluctuation of product performance uniformity in the prior art, and provides hot rolled thin strip steel and a method, wherein the energy consumption can be reduced by more than 70 percent, the carbon dioxide emission can be reduced by more than 60 percent, the surface quality roughness of the product is reduced from 1.5-3 mu m to below 1 mu m, the production flow is further simplified, and a user does not need to acid wash the hot rolled thin strip steel before forming, and the tensile strength of the hot rolled thin strip steel is more than or equal to 1200MPa grade, which is produced by adopting a TSR production line.
Measures for achieving the above object:
the hot rolled thin strip steel with the tensile strength more than or equal to 1200MPa grade produced by adopting a TSR production line comprises the following components in percentage by weight: c:0.12 to 0.20 percent, mn:1.8 to 3.0 percent, P is less than or equal to 0.01 percent, S is less than or equal to 0.01 percent, als:0.015 to 0.050 percent, cr is not more than 1.0 percent, N is not more than 0.005 percent, nb:0.01 to 0.05 percent or V:0.06 to 0.20 percent of one or two of the components are added in a compounding way, and the balance is Fe and unavoidable impurities; the metallographic structure is full martensite or bainite with martensite plus volume ratio not more than 10%.
Preferably: the weight percentage content of Cr is 0.46-0.95%.
Further: the weight percentage of the added B is not more than 0.001 percent.
The production method of the hot rolled thin strip steel with the tensile strength more than or equal to 1200MPa grade by adopting a TSR production line comprises the following steps:
1) Conventionally smelting and refining to obtain molten steel with the components;
2) Pouring into a blank: strip casting is carried out using a twin roll casting apparatus to obtain cast strip, during which: controlling molten steel to perform thin strip continuous casting under the protection of conventional inert gas, wherein the blank pulling speed is 46-117 m/min, and the thickness of a continuous casting strip is 1.0-2.5 mm;
3) And (3) hot rolling: hot rolling the cast strip to a product thickness of 0.5-2.0 mm during: controlling the single-pass reduction ratio to be 20-60% and the finishing temperature to be 850-1000 ℃;
4) Cooling, namely cooling to the coiling temperature by adopting laminar flow type or aerosol type cooling at the cooling speed of not less than 50 ℃/s;
5) Naturally cooling to room temperature after coiling, and controlling the coiling temperature to be not more than 270 ℃;
6) And (5) cold forming is carried out after uncoiling and blanking.
Further: the coiling temperature is 180-265 ℃.
The action and mechanism of each element and main process in the invention:
c: carbon is the basic element in steel and is also the most economical and effective strengthening element. The design of the carbon content is low, and the strength is reduced after hot stamping forming; however, too high a carbon content reduces the plasticity of the steel and is disadvantageous in terms of weldability. Therefore, the carbon percentage content in the invention is controlled to be in the range of 0.12-0.20% from the economical and comprehensive performance viewpoints.
Mn: manganese has solid solution strengthening effect, and is one of important elements for improving the strength of the material; however, too high a manganese content tends to adversely affect weldability. Therefore, the upper limit of manganese is set to 3.0%, and the content of manganese added in the invention is 1.8-3.0%.
P: phosphorus is a harmful element in steel, and is easy to cause center segregation of casting blanks. Grain boundaries are easily segregated in the subsequent hot continuous rolling heating process, so that the brittleness of the steel is remarkably increased. Meanwhile, the content of the alloy is controlled below 0.01% based on cost consideration and without affecting the performance of the steel.
S sulfur is a very harmful element. Sulfur in steel is often present in the form of manganese sulfides, which inclusions deteriorate the toughness of the steel and cause anisotropy of properties, and therefore, it is necessary to control the sulfur content of the steel to be as low as possible. The sulfur content in the steel is controlled below 0.01% based on the manufacturing cost.
Als: aluminum is added for deoxidization, and when the content of Als is less than 0.015%, the effect thereof cannot be exerted; on the other hand, alumina agglomerates and inclusions are easily formed by adding a large amount of aluminum; therefore, the aluminum content is controlled to be in the range of 0.015 to 0.050%.
Cr is an important element for improving the hardenability of steel, and is dissolved in austenite to improve the stability of the austenite, thereby being beneficial to improving the hardenability of the steel; meanwhile, chromium can improve the tempering stability of steel. And after the chromium content exceeds 1.0%, the effect of improving the hardenability is rich, and the cast strip obtained by continuous casting is easy to generate surface cracks at high drawing speed, so that the strip breakage and steel leakage are caused or the surface quality of the product is affected. Therefore, the chromium content is controlled below 1.0%, and the weight percentage of Cr is preferably 0.46-0.95%.
Nitrogen can improve the strength of the steel; however, the binding force of nitrogen, niobium and vanadium is strong, coarse niobium nitride and vanadium nitride can be formed in the high Wen Shigang, and the plasticity and toughness of the steel are seriously damaged; in addition, higher nitrogen content increases the micro-alloying element content required to stabilize the nitrogen element, thereby increasing costs. Therefore, the content of nitrogen element should be reduced as much as possible, and the nitrogen content in the present invention is controlled to be less than 0.005%.
Nb: niobium is a strong C, N carbide forming element. A small amount of niobium is added into the steel to form a certain amount of niobium carbon and niobium nitride, thereby preventing austenite grains from growing and refining the austenite grains, and greatly improving the strength and toughness of the steel after hot forming quenching; the purpose of adding a small amount of titanium into the steel is to fix the N element in the steel and avoid the combination of B and N. However, excessive niobium combines with C to form coarse carbonitrides, thereby reducing the hardness and strength of the martensite after quenching of the test steel. Therefore, the total content thereof is controlled to be in the range of 0.01 to 0.05%.
V is also a strong C, N compound forming element, can play a role in refining austenite grains, and a certain amount of niobium carbon and niobium nitride can be formed by adding a small amount of vanadium into the steel, so that the austenite grains are prevented from growing, and therefore, the quenched martensite lath is smaller in size, and the strength of the steel is greatly improved. So the content is controlled to be between 0.06 and 0.20 percent.
The element B is optional in the invention. Boron is an element for strongly improving the hardenability, and only a trace amount of boron is added to have obvious influence, so that the hardenability can be improved in multiple times, and other expensive metal elements are saved. The hardenability of the steel can be obviously improved by adding trace boron elements into the steel; however, the boron content is higher than 0.001%, and the cast strip obtained by continuous casting is easy to generate surface cracks at high drawing speed, thereby causing strip breakage and steel leakage or affecting the surface quality of the product. Therefore, the boron content in the present invention is controlled to 0.001% or less.
The invention controls molten steel to carry out thin strip continuous casting under the protection of conventional inert gas, and the thickness of the casting strip is 1.0-2.5 mm, because of the thinner original casting strip thickness, the subsequent hot rolling thinning pass can be effectively reduced, and the production energy consumption is reduced; however, the thickness of the cast strip is too thin, and the cast strip is easy to break under high stretching of cast rolling, so that the production continuity is affected. The molten steel is controlled to carry out continuous casting of the thin strip under the protection of conventional inert gas, so that the surface oxidation of the continuous casting thin strip can be avoided, the production strip breakage caused by pressing oxide into the continuous casting thin strip is prevented, and the surface quality of a product is improved.
The invention controls the single-pass reduction ratio to be 20-60%, and the finishing temperature to be 850-1000 ℃, which is beneficial to improving the material strength because the larger hot rolling reduction ratio can refine the grain of the strip steel. However, the single pass rolling reduction is too large, which is disadvantageous for controlling the plate shape, and the rolling load increases; considering that the patent only adopts single hot rolling, the rolling reduction is controlled within 60 percent in order to ensure that the shape and thickness precision of the product plate are controllable. In order to avoid the influence on the material performance caused by mixed crystal in the hot rolling stage, the final rolling temperature cannot be lower than the cooling recrystallization temperature of high-temperature austenite; meanwhile, the oxidation thickness of the surface of the strip steel increases along with the increase of the finishing temperature, so the finishing temperature of the invention is controlled within 850-1000 ℃.
The casting speed of the present invention is preferably 46-117 m/min because the casting speed is related to the drawing speed of the continuous casting thin strip and the steel production efficiency. The high pulling speed is beneficial to improving the production efficiency, but molten steel is easy to solidify in time in the double-roll casting machine, and the breakage and the steel leakage of the casting belt are induced; lower stretching will affect production efficiency, increase production costs, simultaneously will lead to cold hardening of the cast strip, increase subsequent rolling load and energy consumption, and be detrimental to control of strip shape.
The cooling speed is controlled to be not lower than 50 ℃/s and cooled to be lower than 270 ℃, and the cooling coiling temperature is preferably 180-265 ℃, because the critical cooling speed and the critical final temperature of the thin steel plate which is developed by the invention and is converted into martensite in the cooling process are controlled, otherwise, the thin steel plate cannot be sufficiently cooled to the required strength; the plate strip waste heat can be used for carrying out self-tempering treatment on the temperature of the plate, so that the internal stress generated during cooling is reduced or eliminated, and the plasticity of the strip steel is improved; meanwhile, the strip steel can utilize waste heat to reduce the deformation resistance of the strip steel, and is convenient to curl.
Compared with the prior art, the invention not only can ensure the mechanical property of martensitic steel with the tensile strength of 1200MPa grade by adding Nb, V or the composite addition of the Nb and the V and controlling the elements such as Cr and B in the components and adopting a TSR short flow process, but also can reduce the procedures of repeated heating, dephosphorization, multipass rolling and the like of strip steel in the production process, and can cancel the procedures of cold rolling and annealing heat treatment, thereby reducing the energy consumption by more than 80 percent and reducing the carbon dioxide emission by more than 70 percent, reducing the roughness of the surface quality of the product from the traditional 1.5-3 mu m to less than 1 mu m, and ensuring that a user does not need to carry out acid washing before forming.
Drawings
FIG. 1 is a view showing the metallographic structure of a steel sheet according to the present invention as fully martensitic.
Detailed Description
The present invention will be described in detail below:
table 1 is a listing of chemical components of each example and comparative example of the present invention;
table 2 is a list of the main process parameters for each example and comparative example of the present invention;
table 3 shows a list of performance test results for each of the examples and comparative examples of the present invention.
The production of each embodiment of the invention is carried out according to the following steps:
1) Conventionally smelting and refining to obtain molten steel with the components;
2) Pouring into a blank: strip casting is carried out using a twin roll casting apparatus to obtain cast strip, during which: controlling molten steel to perform thin strip continuous casting under the protection of conventional inert gas, wherein the blank pulling speed is 46-117 m/min, and the thickness of a continuous casting strip is 1.0-2.5 mm;
3) And (3) hot rolling: hot rolling the cast strip to a product thickness of 0.5-2.0 mm during: controlling the single-pass reduction ratio to be 20-60% and the finishing temperature to be 850-1000 ℃;
4) Cooling, namely cooling to the coiling temperature by adopting laminar flow type or aerosol type cooling at the cooling speed of not less than 50 ℃/s;
5) Naturally cooling to room temperature after coiling, and controlling the coiling temperature to be not more than 270 ℃;
6) And (5) cold forming is carried out after uncoiling and blanking.
Table 1 chemical composition (wt.%) of each example and comparative example of the present invention
Table 2 list of values of the main process parameters for each example and comparative example of the present invention
TABLE 3 Performance test results for each example and comparative example of the present invention
As can be seen from Table 3, the direct cold forming tensile strength of the inventive steel sheet reaches over 1200MPa by the TSR twin-roll strip casting process, which is much higher than the strength of the existing TSR production line products; the method has important significance for propelling the light-weight horizontal lifting of the automobile and reducing the energy consumption and carbon emission of steel production.
This embodiment is merely a best example and is not intended to limit the implementation of the technical solution of the present invention.
Claims (2)
1. The hot rolled thin strip steel with the tensile strength more than or equal to 1200MPa grade produced by adopting a TSR production line comprises the following components in percentage by weight: c:0.12 to 0.20 percent, mn:2.71 to 3.0 percent, P is less than or equal to 0.01 percent, S is less than or equal to 0.01 percent, als: 0.031-0.050%, cr:0.81 to 1.0 percent, N is less than or equal to 0.005 percent, nb:0.01 to 0.05 percent or V:0.13 to 0.20 percent of one or two of the components are added in a compounding way, and the balance is Fe and unavoidable impurities; the metallographic structure is full martensite or bainite with martensite added volume ratio not more than 10%; the production steps are as follows:
1) Conventionally smelting and refining to obtain molten steel;
2) Pouring into a blank: strip casting is carried out using a twin roll casting apparatus to obtain cast strip, during which: controlling molten steel to perform thin strip continuous casting under the protection of conventional inert gas, wherein the blank pulling speed is 46-50 m/min, and the thickness of a continuous casting strip is 1.0-2.5 mm;
3) And (3) hot rolling: hot rolling the cast strip to a product thickness of 0.5-2.0 mm during: the single-pass reduction rate is controlled to be 56-60%,
the final rolling temperature is 850-1000 ℃;
4) Cooling, namely cooling to the coiling temperature at the cooling speed of 50-72 ℃ per second by adopting laminar flow type or aerosol type cooling;
5) Naturally cooling to room temperature after coiling, and controlling the coiling temperature to be not more than 245 ℃;
6) And (5) cold forming is carried out after uncoiling and blanking.
2. The method for producing hot rolled thin strip steel with tensile strength not less than 1200MPa grade by adopting a TSR production line according to claim 1, comprising the steps of:
1) Conventionally smelting and refining to obtain molten steel;
2) Pouring into a blank: strip casting is carried out using a twin roll casting apparatus to obtain cast strip, during which: controlling molten steel to perform thin strip continuous casting under the protection of conventional inert gas, wherein the blank pulling speed is 46-50 m/min, and the thickness of a continuous casting strip is 1.0-2.5 mm;
3) And (3) hot rolling: hot rolling the cast strip to a product thickness of 0.5-2.0 mm during: the single-pass reduction rate is controlled to be 56-60%,
the final rolling temperature is 850-1000 ℃;
4) Cooling, namely cooling to the coiling temperature at the cooling speed of 50-72 ℃ per second by adopting laminar flow type or aerosol type cooling;
5) Naturally cooling to room temperature after coiling, and controlling the coiling temperature to be not more than 245 ℃;
6) And (5) cold forming is carried out after uncoiling and blanking.
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| CN100372962C (en) * | 2005-03-30 | 2008-03-05 | 宝山钢铁股份有限公司 | Superhigh strength steel plate with yield strength more than 1100Mpa and method for producing same |
| CN100494451C (en) * | 2005-03-30 | 2009-06-03 | 宝山钢铁股份有限公司 | Superhigh strength steel plate with yield strength more than 960Mpa and method for producing same |
| JP5277648B2 (en) * | 2007-01-31 | 2013-08-28 | Ｊｆｅスチール株式会社 | High strength steel sheet with excellent delayed fracture resistance and method for producing the same |
| CN103302255B (en) * | 2012-03-14 | 2015-10-28 | 宝山钢铁股份有限公司 | A kind of thin strap continuous casting 700MPa level high-strength air corrosion-resistant steel manufacture method |
| CN103305755B (en) * | 2012-03-14 | 2015-10-28 | 宝山钢铁股份有限公司 | The high-strength steel band manufacture method of a kind of thin strap continuous casting low-carbon microalloy |
| CN103266274B (en) * | 2013-05-22 | 2015-12-02 | 宝山钢铁股份有限公司 | A kind of superhigh intensity cold rolling weather resisting steel plate and manufacture method thereof |
| CN106222555B (en) * | 2016-08-24 | 2018-03-20 | 武汉钢铁有限公司 | With the thin hot forming steel of tensile strength >=1300MPa of sheet billet Direct Rolling and production method |
| CN112522571B (en) * | 2019-09-19 | 2022-03-18 | 宝山钢铁股份有限公司 | Method for producing martensite steel strip by twin-roll thin-strip continuous casting |
| CN112522576B (en) * | 2019-09-19 | 2022-11-18 | 宝山钢铁股份有限公司 | Thin-gauge high-corrosion-resistance steel and production method thereof |
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