CN113025918A - 800MPa steel based on multi-mode sheet billet continuous casting and rolling production line and production method thereof - Google Patents
800MPa steel based on multi-mode sheet billet continuous casting and rolling production line and production method thereof Download PDFInfo
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/18—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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- 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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- 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
- C21D9/46—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for sheet metals
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- C22C33/00—Making ferrous alloys
- C22C33/04—Making ferrous alloys by melting
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- C22C38/06—Ferrous alloys, e.g. steel alloys containing aluminium
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- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/22—Ferrous alloys, e.g. steel alloys containing chromium with molybdenum or tungsten
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- 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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- 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
- C22C38/28—Ferrous alloys, e.g. steel alloys containing chromium with titanium or zirconium
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D2211/00—Microstructure comprising significant phases
- C21D2211/005—Ferrite
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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
- C21D2211/009—Pearlite
Abstract
The invention provides 800MPa steel based on a multi-mode sheet billet continuous casting and rolling production line, which belongs to the technical field of steel, and comprises the following chemical components in percentage by mass: c: 0.03-0.15%, Si: less than or equal to 0.05 percent, Mn: 1.3-2.1%, Al: 0.02-0.35%, P: less than or equal to 0.010, S: not more than 0.005, Nb: 0.010-0.10%, Mo: 0.10-0.30%, Ti: 0.015-0.15%, Cr: 0.1-0.5%, N: less than or equal to 0.005 percent, and the balance of Fe and inevitable impurities. By improving the chemical components, the production line and the preparation method of the steel, the obtained steel plate has good shape, high dimensional precision and small strength fluctuation. The invention also provides a production method of 800MPa steel based on the multi-mode thin slab continuous casting and rolling production line.
Description
Technical Field
The invention belongs to the technical field of steel, and relates to 800MPa steel based on a multi-mode thin slab continuous casting and rolling production line and a production method thereof.
Background
Driven by the factors of 'replacing cold with heat', reducing cost, saving energy, reducing emission, shortening flow, improving efficiency and the like, the market has ever-increasing demand on high-performance thin/ultrathin hot-rolled strip steel, and the endless rolling technology has obvious effects on improving the product proportion, yield, size and shape precision and structural property uniformity of ultrathin strip steel, reducing energy consumption and roller consumption, saving energy and reducing emission. In recent years, several ESP production lines are put into production in domestic enterprises represented by Japanese steel, and common low-carbon ultrathin sheets and high-strength ultrathin hot rolled sheet products can be stably, reliably and accurately produced. The difference between the multi-mode thin slab continuous casting and rolling production line and the conventional ESP production line is that: the thickness of the plate blank is increased by 20-30mm compared with that of an ESP production line, a roller hearth type tunnel furnace is additionally arranged between the outlet of a continuous casting machine and rough rolling, the tunnel furnace comprises a fixed section and a movable section, the plate blank offline function is realized, single-blank, semi-endless and full-endless multi-mode rolling can be realized, and the product thickness range is expanded.
The high-strength steel can meet the safety and use requirements and achieve the purposes of weight reduction, energy conservation and emission reduction, becomes a new generation of environment-friendly material, is widely applied to the fields of engineering machinery, automobile manufacturing, container manufacturing and the like, and has increasingly expanded demand and good market prospect. The 800 MPa-grade high-strength steel is widely applied to the fields of automobile girders, automobile frames, carriages, crane booms and container carriage plates in the engineering machinery industry and the like, replaces low-strength-grade products, and realizes the reduction production. At present, 800 MPa-level high-strength steel is still produced by adopting a traditional hot continuous rolling production line, the traditional production line has the current situations of high production cost, long process flow, low efficiency, higher energy consumption and the like, and the traditional production line has the defects of poor plate shape, large strength fluctuation, poor dimensional precision control stability and the like in the aspect of product quality in the production of thin (1.5-4.0mm)800MPa high-strength steel. Therefore, a new production process of 800MPa high-strength steel is urgently needed to be developed.
Disclosure of Invention
In order to solve the technical problem that the precision and mechanical property of the thin 800MPa high-strength steel produced by the traditional production line fluctuate greatly, the invention provides the 800MPa steel based on the multi-mode thin slab continuous casting and rolling production line, and the tensile strength of the obtained steel reaches over 800MPa by improving the chemical components, the production line and the preparation method of the steel, and the steel has high dimensional precision and small strength fluctuation.
The invention also provides a production method of 800MPa steel based on the multi-mode sheet billet continuous casting and rolling production line, which can achieve the purposes of energy conservation, consumption reduction, environmental protection and cost reduction by using the multi-mode sheet billet continuous casting and rolling production line for production.
The invention is realized by the following technical scheme:
the 800MPa steel based on the multi-mode sheet billet continuous casting and rolling production line comprises the following chemical components in percentage by mass:
c: 0.03-0.15%, Si: less than or equal to 0.05 percent, Mn: 1.3-2.1%, AI: 0.02-0.35%, P: less than or equal to 0.010, S: not more than 0.005, Nb: 0.010-0.10%, Mo: 0.10-0.30%, Ti: 0.015-0.15%, Cr: 0.1-0.5%, N: less than or equal to 0.005 percent, and the balance of Fe and inevitable impurities;
the metallographic structure of the steel is calculated by volume fraction as follows: 85-95% of ferrite, and the balance of pearlite;
the grain size of the ferrite is 2.5-4.0 μm;
the thickness of the steel is 1.0-12.7 mm.
A production method of 800MPa steel based on a multi-mode thin slab continuous casting and rolling production line comprises the following steps:
obtaining molten steel of 800MPa steel based on the multi-mode sheet billet continuous casting and rolling production line;
continuously casting the molten steel into a plate blank;
heating the plate blank, and then sequentially carrying out rough descaling, rough rolling, induction heating, fine descaling, finish rolling, laminar cooling, coiling and air cooling on the plate blank to obtain the 800MPa steel based on the multi-mode thin slab continuous casting and rolling production line;
the heating temperature of the slab is 1150-1200 ℃.
Further, the continuous casting speed of the molten steel is 3.5-6.5m/min, and the thickness of the plate blank is 110-123 mm.
Further, the dephosphorization pressure of the slab rough dephosphorization is more than or equal to 30 MPa.
Further, the inlet temperature of the rough rolling is more than or equal to 1150 ℃, 3-pass rolling is adopted, and the outlet temperature of the rough rolling is controlled to be 930-1000 ℃.
Further, the temperature of the induction heating outlet is controlled to be 1050-.
Further, the finish rolling is performed by any one of single billet rolling, semi-endless rolling and endless rolling;
when the single billet rolling is adopted in the finish rolling, double rows of phosphorus removal are adopted in the finish descaling, and the phosphorus removal pressure is more than or equal to 30 MPa;
when the semi-endless rolling or endless rolling is adopted for the finish rolling, the finish descaling adopts single-row dephosphorization, and the dephosphorization pressure is more than or equal to 30 MPa;
in the fine descaling, the distance between the dephosphorization nozzle and the slab is 60-110 mm.
Furthermore, the finish rolling adopts 5 passes of rolling, the accumulated deformation of the finish rolling is 70-80%, and the finish rolling temperature is controlled to be 820-.
Further, the cooling speed of the laminar cooling is more than or equal to 35 ℃/s, the coiling temperature is controlled to be 560 ℃ and 660 ℃, and the obtained steel coil is air-cooled to the room temperature.
Optionally, the molten steel is prepared by KR desulfurization, converter smelting, LF refining and VD refining in sequence.
One or more technical solutions in the embodiments of the present invention have at least the following technical effects or advantages:
1. the invention relates to 800MPa steel based on a multi-mode sheet billet continuous casting and rolling production line, which is produced based on the multi-mode sheet billet continuous casting and rolling production line, the component design mainly adopts a C-Si-Mn-Nb-Mo-Ti-Ct component system, the strength of the material is ensured mainly by solid solution strengthening of C, Mn, fine grain strengthening of Nb and precipitation strengthening of Nb-Mo-Ti-Cr, the yield strength of the obtained steel is more than 730MPa, the tensile strength is 800-880MPa, the elongation is more than 21 percent, transverse cold bending D is 0a and 180 degrees are qualified by combining the improvement of a rolling process, and the thickness of a steel plate can reach 1.0-12.7 mm.
2. The invention relates to a production method of 800MPa steel based on a multi-mode sheet billet continuous casting and rolling production line, which is characterized in that a rough rolling process and a finish rolling process are adopted to remove phosphorus twice to ensure the surface quality of strip steel, an intermediate billet is subjected to induction heating before finish rolling, carbonitrides of Nb and Ti formed by the rough rolling process are redissolved, Nb is separated out again in the finish rolling process, austenite grains are refined, ferrite grains are refined, Mo and Ti microalloy elements are separated out in a small amount in the finish rolling process, the (Ti, Nb and Mo) C form is separated out mainly in a laminar cooling process and a coiling process to improve the strength of the material, laminar cooling is adopted after rolling, the coiling temperature is adjusted according to different strip steel thicknesses to obtain 800MPa hot rolled strip steel with uniform performance, and the strip steel has good plate type, high dimensional accuracy and small strength fluctuation.
Drawings
In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings needed to be used in the description of the embodiments are briefly introduced below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings based on the drawings without creative efforts.
FIG. 1 is a process flow diagram of the present invention;
FIG. 2 is a metallographic structure diagram of a steel coil in example 3 of the present invention.
Detailed Description
The present invention will be described in detail below with reference to specific embodiments and examples, and the advantages and various effects of the present invention will be more clearly apparent therefrom. It will be understood by those skilled in the art that these specific embodiments and examples are for the purpose of illustrating the invention and are not to be construed as limiting the invention.
Throughout the specification, unless otherwise specifically noted, terms used herein should be understood as having meanings as commonly used in the art. Accordingly, unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. If there is a conflict, the present specification will control.
Unless otherwise specifically stated, various raw materials, reagents, instruments, equipment and the like used in the present invention are commercially available or can be prepared by existing methods.
In order to solve the technical problems, the embodiment of the invention provides the following general ideas:
the invention abandons the traditional hot continuous rolling production line, innovatively adopts a multi-mode thin slab continuous casting and rolling production line to produce 800MPa high-strength steel, improves the chemical components and the preparation process of the steel, obtains the steel with yield strength of more than 730MPa, tensile strength of 800 plus 880MPa, elongation of more than 21 percent, qualified transverse cold bending D of 0a and 180 degrees, and has good steel plate type, high dimensional precision, small strength fluctuation and controllable steel plate thickness of 1.0-12.7 mm.
Specifically, the 800MPa steel based on the multi-mode thin slab continuous casting and rolling production line comprises the following chemical components in percentage by mass:
c: 0.03-0.15%, Si: less than or equal to 0.05 percent, Mn: 1.3-2.1%, AI: 0.02-0.35%, P: less than or equal to 0.010, S: not more than 0.005, Nb: 0.010-0.10%, Mo: 0.10-0.30%, Ti: 0.015-0.15%, Cr: 0.1-0.5%, N: less than or equal to 0.005 percent, and the balance of Fe and inevitable impurities;
the metallographic structure of the steel is calculated by volume fraction as follows: 85-95% of ferrite, and the balance of pearlite;
the grain size of the ferrite is 2.5-4.0 μm;
the thickness of the steel is 1.0-12.7 mm.
A production method of 800MPa steel based on a multi-mode thin slab continuous casting and rolling production line comprises the following steps:
obtaining molten steel of 800MPa steel based on the multi-mode sheet billet continuous casting and rolling production line;
continuously casting the molten steel into a plate blank;
heating the plate blank, and then sequentially carrying out rough descaling, rough rolling, induction heating, fine descaling, finish rolling, laminar cooling, coiling and air cooling on the plate blank to obtain the 800MPa steel based on the multi-mode thin slab continuous casting and rolling production line;
the heating temperature of the slab is 1150-1200 ℃.
Further, the continuous casting speed of the molten steel is 3.5-6.5m/min, and the thickness of the plate blank is 110-123 mm.
Further, the dephosphorization pressure of the slab rough dephosphorization is more than or equal to 30 MPa.
Further, the inlet temperature of the rough rolling is more than or equal to 1150 ℃, 3-pass rolling is adopted, and the outlet temperature of the rough rolling is controlled to be 930-1000 ℃.
Further, the temperature of the induction heating outlet is controlled to be 1050-.
Further, the finish rolling is performed by any one of single billet rolling, semi-endless rolling and endless rolling;
when the finish rolling adopts single-billet rolling, the fine descaling adopts double-row dephosphorization, and the dephosphorization pressure is more than or equal to 30 MPa;
when the finish rolling adopts semi-endless rolling or endless rolling, the finish descaling adopts single-row dephosphorization, and the dephosphorization pressure is more than or equal to 30 MPa;
in the fine descaling, the distance between the dephosphorization nozzle and the slab is 60-110 mm.
Furthermore, the finish rolling adopts 5-pass rolling, the accumulated deformation of the finish rolling is 70-80%, and the finish rolling temperature is controlled to be 820-880 ℃.
Further, the cooling speed of the laminar cooling is more than or equal to 35 ℃/s, the coiling temperature is controlled to be 560 ℃ and 660 ℃, and the obtained steel coil is air-cooled to the room temperature.
Optionally, the molten steel is prepared by KR desulfurization, converter smelting, LF refining and VD refining in sequence.
The main alloy elements of the invention have the following functions and limited ranges:
c: carbon is the most important alloy element in steel and is one of the most economical elements for improving the strength, carbon atoms are limitedly and fixedly dissolved in gamma-Fe, a gamma phase region is enlarged, the influence on the structure and the performance is great, the strength and the hardness are mainly controlled, and the carbon and the micro alloy elements form carbonitrides to adjust the performance of the steel in a large range. The steel with too high carbon content is easy to form a banded structure in the slab smelting and rolling processes, the severe banded structure has adverse effects on the cold forming performance and the fatigue performance of the steel plate, and in addition, the C content is high, which is adverse to the welding performance of the material. If the carbon content is too low or even ultra-low, the smelting difficulty is increased. In order to meet the requirements of strength of S500MC with different thicknesses, C content is controlled as follows: 0.03 to 0.15 percent.
Si: in the invention, Si mainly influences the surface quality of hot-rolled strip steel, pickled steel plates and hot-dip galvanized strip steel, and according to the Sandlin effect, when the Si content is controlled to be below 0.05 percent, the coating structure is basically not influenced by silicon, and a bright coating with normal thickness can be obtained. In order to ensure the surface quality of the strip steel, Si is controlled to be less than or equal to 0.05 percent.
Mn: manganese and iron can be mutually replaced, and are replaced solute atoms in the iron-based solid solution, so that the Mn solid solution strengthening effect is good. Manganese, which is an austenite-forming element, also refines grains to improve strength, and expands a single austenite phase region. Manganese can lower the temperature of gamma → alpha transition obviously, so that the point A1 can be lowered, and ferrite grains can be refined. Manganese content design is primarily considered in terms of both performance requirements and production costs. In terms of production cost, manganese is the most economical alloying element for enlarging the austenite region, and meanwhile, manganese and sulfur form MnS, which is beneficial to improving the sulfide form in the test steel. However, too high manganese content as an alloying element increases the production cost of the test steel. Therefore, manganese is controlled to be 1.3 to 2.1%.
S, P and N: s, P and N elements are too high, which adversely affects the plasticity, toughness and fatigue properties of the material. The invention limits the S content to be controlled within 0.005%, the P content to be controlled within 0.015% and the N content to be controlled within 0.005%.
Nb: nb is one of key strengthening elements in HSLA steel, and has various strengthening mechanisms such as solid solution strengthening and precipitation in the thermomechanical process. The solid solution of Nb can obviously improve the dynamic recrystallization temperature of steel, thereby promoting the generation of deformation induced ferrite and precipitation through non-zone rolling; the dispersed precipitates of Nb can strengthen the matrix through the dragging effect on dislocation, and also can refine grains through the pinning effect on grain boundaries, thereby improving the strength of the steel. In addition, Nb can also ensure the refinement of weld joint structure and improve the strength after welding. Considering the cost factor, the production cost of the material is increased due to the excessively high Nb content, and Nb is controlled to be 0.010-0.10%.
Ti: titanium is a ferrite-forming element that expands the single austenite phase region, with a maximum solubility of 0.75% for Ti in pure gamma-Fe and a maximum solubility of about 6% for pure alpha-Fe. Ti is a strong carbonitride element that first forms TiN in the steel, the size of TiN particles being related to its precipitation process. Coarse TiN (> 0.5 μm) is a precipitated phase in the liquid state or molten steel solidification process, and cannot effectively prevent the crystal grains from growing due to coarse and sparse distribution, and does not play a role in strengthening. Fine TiN particles are precipitated after the molten steel is solidified, and the fine TiN particles are very stable and can effectively prevent austenite grains from growing large, so that the structure is refined. As the Ti content increases, TiN particles coarsen, the amount of fine TiC increases, and the precipitation strengthening effect causes the strength of the steel to be obviously improved along with the increase of the Ti content. The fine TiC precipitation in the steel is influenced by the transformation temperature, the higher the transformation temperature is, the greater the tendency of the precipitated particles to lose the coherent relationship is, and the precipitation strengthening is weakened through diffusion and growth. Therefore, at a higher Ti content, the number of non-coherent precipitates increases, and the precipitation strengthening effect is weakened. The Ti-containing second phase particles can prevent the growth of a coarse crystal area in the welding process and refine crystal grains, and the two kinds of particles jointly act to improve the welding performance of the steel.
Mo: mo is an important alloy element, and the difference and the interaction between the Mo and Fe, C and other alloy elements in the atomic structure, the size and the crystal lattice can improve the strength, the toughness, the hardness and the wear resistance of steel, and can also improve the hardenability, the hardenability and the delayed fracture resistance of the steel. Mo element is combined with Ti, Nb and V to form composite carbide, the precipitated carbide is finer along with the increase of Mo content, the fine carbide precipitates mainly on dislocation lines of a ferrite region, the elimination of dislocation at high temperature is hindered by the addition of Mo, the dislocation density in a matrix is increased, more positions are provided for nucleation of the carbide, the number of precipitated phases is increased, and the strength of the material is increased. But Mo is a more expensive alloy element, and the content of Mo is controlled to be below 0.30 percent.
Al: al is one of effective deoxidizing elements, and can form nitrides to refine grains. Too high Al content impairs the toughness of the steel and also deteriorates the toughness of the weld heat-affected zone.
Cr: cr is an element with strong hardenability, plays a role in solid solution strengthening in a matrix, and is added with a proper amount in order to obtain finer ferrite grains, so that the hardenability of the material is improved, and the grains are refined. However, excessive Cr element can cause the welding performance of the material to be deteriorated, so the invention controls the content of the Cr element to be 0.1-0.5%.
The production process adopted by the invention has the following control key points:
based on the production of multi-mode sheet billet continuous casting and rolling production line, multi-mode sheet billet continuous casting and rolling production line compares traditional production line, has increased a roller hearth type tunnel furnace between conticaster export and the rough rolling, and the tunnel furnace includes fixed section and removal section, possesses the slab function of inserting the production line, can realize single billet, half endless and full endless multi-mode rolling, expands product thickness range.
The molten iron is subjected to KR desulfurization pretreatment and a conventional converter smelting process, and LF and VD double refining treatment is adopted to obtain molten steel with required components.
The continuous casting speed is controlled to be 3.5-6.5m/min, the thickness of the casting blank is 110-.
And phosphorus removal is carried out before rough rolling, and the phosphorus removal pressure is more than or equal to 30 MPa. The rough rolling adopts irreversible 3-pass rolling, and the temperature of the outlet of the rough rolling is controlled to be 930-1000 ℃. In order to ensure the final rolling temperature, the slab is heated by electromagnetic induction after rough rolling, and the heating outlet temperature is controlled at 1050-. The finish rolling adopts 5-pass rolling, the accumulated deformation of the finish rolling is 70-80%, and the finishing temperature is controlled to be 800-880 ℃. After rolling, laminar cooling is adopted, the coiling temperature is controlled to be 560-.
According to the rolling mode, different phosphorus removal modes are adopted before finish rolling, double-row phosphorus removal is adopted for single-billet rolling, single-row phosphorus removal is adopted for semi-endless or endless rolling, phosphorus removal pressure is larger than or equal to 30MPa, the distance between a phosphorus removal nozzle and a slab is adjusted according to the thickness of the slab, and the adjustment range is 60-110 mm.
This patent is based on multi-mode sheet bar continuous casting and rolling production line production 800MPa hot rolling steel, and the component design mainly adopts C-Si-Mn-Nb-Mo-Ti-Cr composition system, mainly relies on C, Mn solid solution strengthening, the fine grain of Nb reinforce and the precipitation strengthening of Nb-Mo-Ti-Cr to guarantee the intensity of material, and in the cast rolling process, adopts two times dephosphorization of rough rolling and finish rolling, guarantees the surface quality of belted steel. And induction heating is carried out on the intermediate billet before finish rolling, so that carbo-nitrides of Nb and Ti formed in the rough rolling are redissolved, Nb is separated out again in the finish rolling stage, austenite grains are refined, and ferrite grains are further refined. The micro-alloying elements Mo and Ti are less precipitated in the finish rolling stage, and are mainly precipitated in the (Ti, Nb, Mo) C form in the laminar cooling process and the coiling stage, so that the strength of the material is improved. After rolling, laminar cooling is adopted, and the coiling temperature is adjusted according to different strip steel thicknesses to obtain 800MPa hot rolled strip steel with uniform performance.
The following will explain in detail an 800MPa steel based on multi-mode thin slab continuous casting and rolling production line and its production method in combination with examples, comparative examples and experimental data.
Examples
800MPa steel based on a multi-mode sheet billet continuous casting and rolling production line is prepared by the following method:
(1) performing KR desulfurization, conventional converter smelting and LF and VD furnace double refining treatment to obtain target molten steel, wherein the molten steel comprises the following chemical components in percentage by mass:
c: 0.03-0.15%, Si: less than or equal to 0.05 percent, Mn: 1.3-2.1%, AI: 0.02-0.35%, P: less than or equal to 0.010, S: not more than 0.005, Nb: 0.010-0.10%, Mo: 0.10-0.30%, Ti: 0.015-0.15%, Cr: 0.1-0.5%, N: less than or equal to 0.005 percent, and the balance of Fe and inevitable impurities.
(2) Continuously casting the molten steel into a plate blank: the pulling speed of the plate blank is 3.5-6.5m/min, and the thickness of the plate blank is 110-123 mm.
(3) The soaking temperature of the slab in a tunnel furnace of the multi-mode sheet billet continuous casting and rolling production line is 1150-plus-1200 ℃, rough phosphorus removal is carried out before rough rolling, the phosphorus removal pressure is not less than 30MPa, the inlet temperature of the rough rolling is not less than 1150 ℃, the rough rolling adopts irreversible 3-pass rolling, and the outlet temperature of the rough rolling is controlled to 930-plus-1000 ℃.
(4) Induction heating and rough descaling are carried out before finish rolling, the temperature of an induction heating outlet is controlled to be 1050-;
when the finish rolling adopts single-billet rolling, the fine descaling adopts double-row dephosphorization, and the dephosphorization pressure is more than or equal to 30 MPa;
when the finish rolling adopts semi-endless rolling or endless rolling, the finish descaling adopts single-row dephosphorization, and the dephosphorization pressure is more than or equal to 30 MPa;
in the fine descaling, the distance between the dephosphorization nozzle and the slab is 60-110 mm.
(5) Finish rolling: the finish rolling adopts 5-pass rolling, the accumulated deformation of the finish rolling is 70-80%, the finish rolling temperature is controlled to be 820-.
The chemical compositions of the steels of the examples of the invention are shown in table 1, table 2 shows the manufacturing process of the steels of the examples of the invention, and table 3 shows the mechanical properties of the steels of the examples of the invention.
TABLE 1 thickness and chemical composition of steels of examples 1-10 and comparative examples 1-3
| Examples | Thickness of | C | Si | Mn | P | S | AIs | Nb | Ti | Mo | Cr | N |
| 1 | 1.0 | 0.045 | 0.032 | 1.66 | 0.009 | 0.0020 | 0.035 | 0.025 | 0.095 | 0.15 | 0.25 | 0.004 |
| 2 | 1.2 | 0.033 | 0.035 | 1.75 | 0.008 | 0.0040 | 0.030 | 0.020 | 0.105 | 0.17 | 0.28 | 0.003 |
| 3 | 1.5 | 0.042 | 0.030 | 1.80 | 0.006 | 0.0030 | 0.042 | 0.018 | 0.102 | 0.12 | 0.32 | 0.003 |
| 4 | 2.0 | 0.041 | 0.028 | 1.83 | 0.009 | 0.0040 | 0.033 | 0.023 | 0.10 | 0.19 | 0.34 | 0.003 |
| 5 | 3.0 | 0.043 | 0.031 | 1.83 | 0.007 | 0.0030 | 0.044 | 0.028 | 0.115 | 0.20 | 0.13 | 0.005 |
| 6 | 4.0 | 0.045 | 0.031 | 1.95 | 0.006 | 0.0010 | 0.034 | 0.022 | 0.12 | 0.15 | 0.35 | 0.005 |
| 7 | 6.0 | 0.065 | 0.021 | 1.81 | 0.005 | 0.0050 | 0.034 | 0.034 | 0.131 | 0.25 | 0.41 | 0.004 |
| 8 | 8.0 | 0.12 | 0.042 | 1.82 | 0.004 | 0.0020 | 0.032 | 0.035 | 0.117 | 0.23 | 0.38 | 0.003 |
| 9 | 10.0 | 0.13 | 0.037 | 1.75 | 0.008 | 0.0032 | 0.033 | 0.038 | 0.12 | 0.27 | 0.46 | 0.004 |
| 10 | 12.7 | 0.14 | 0.032 | 2.05 | 0.008 | 0.0038 | 0.043 | 0.051 | 0.13 | 0.25 | 0.42 | 0.004 |
| Comparative example 1 | 1.5 | 0.07 | 0.18 | 1.90 | 0.010 | 0.009 | 0.045 | 0.025 | 0.11 | -- | -- | 0.004 |
| Comparative example 2 | 3.0 | 0.07 | 0.20 | 1.84 | 0.013 | 0.008 | 0.044 | 0.035 | 0.10 | -- | -- | 0.0033 |
| Comparative example 3 | 6.0 | 0.08 | 0.18 | 1.82 | 0.016 | 0.010 | 0.042 | 0.020 | 0.09 | -- | -- | 0.0032 |
TABLE 2 production Process of steels of examples 1-10 and comparative examples 1-3
TABLE 3 mechanical Properties of the steels of examples 1-10 and comparative examples 1-3
As can be seen from tables 1-3: the invention adopts a multi-mode sheet billet continuous casting and rolling production line, adopts a C-Si-Mn-Nb-Mo-Ti-Cr component system by adjusting the chemical components of steel and improving the continuous casting and rolling process, and obtains the steel with yield strength of more than 730Mpa, tensile strength of 800-880Mpa, elongation of more than 21 percent, qualified transverse cold bending D of 0a and 180 degrees, good steel plate type, high dimensional precision, small strength fluctuation and controllable steel plate thickness of 1.0-12.7 mm.
The steels of comparative examples 1 to 3 did not achieve the effects of examples 3, 5 and 7 in terms of yield strength, tensile strength and elongation, compared to examples having the same steel sheet thickness.
Finally, it should also be noted that the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus.
While preferred embodiments of the present invention have been described, additional variations and modifications in those embodiments may occur to those skilled in the art once they learn of the basic inventive concepts. Therefore, it is intended that the appended claims be interpreted as including preferred embodiments and all such alterations and modifications as fall within the scope of the invention.
It will be apparent to those skilled in the art that various changes and modifications may be made in the present invention without departing from the spirit and scope of the invention. Thus, if such modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include such modifications and variations.
Claims (10)
1. The 800MPa steel based on the multi-mode sheet billet continuous casting and rolling production line is characterized by comprising the following chemical components in percentage by mass:
c: 0.03-0.15%, Si: less than or equal to 0.05 percent, Mn: 1.3-2.1%, Al: 0.02-0.35%, P: less than or equal to 0.010, S: not more than 0.005, Nb: 0.010-0.10%, Mo: 0.10-0.30%, Ti: 0.015-0.15%, Cr: 0.1-0.5%, N: less than or equal to 0.005 percent, and the balance of Fe and inevitable impurities;
the metallographic structure of the steel is calculated by volume fraction as follows: 85-95% of ferrite, and the balance of pearlite;
the grain size of the ferrite is 2.5-4.0 μm;
the thickness of the steel is 1.0-12.7 mm.
2. A method for producing 800MPa steel based on a multi-mode thin slab continuous casting and rolling line as claimed in claim 1, characterized in that it comprises:
obtaining molten steel of 800MPa steel based on the multi-mode sheet billet continuous casting and rolling production line;
continuously casting the molten steel into a plate blank;
heating the plate blank, and then sequentially carrying out rough descaling, rough rolling, induction heating, fine descaling, finish rolling, laminar cooling, coiling and air cooling on the plate blank to obtain the 800MPa steel based on the multi-mode thin slab continuous casting and rolling production line;
the heating temperature of the slab is 1150-1200 ℃.
3. The method for producing the 800MPa steel based on the multi-mode thin slab continuous casting and rolling production line as claimed in claim 2, wherein the molten steel continuous casting speed is 3.5-6.5m/min, and the slab thickness is 110-123 mm.
4. The production method of 800MPa steel based on the multi-mode thin slab continuous casting and rolling production line according to claim 2, characterized in that the dephosphorization pressure of the crude dephosphorization is more than or equal to 30 MPa.
5. The method for producing the 800MPa steel based on the multi-mode thin slab continuous casting and rolling production line as claimed in claim 2, wherein the rough rolling inlet temperature is more than or equal to 1150 ℃, and the rough rolling outlet temperature is controlled to 930-1000 ℃ by adopting 3-pass rolling.
6. The method for producing 800MPa steel based on multi-mode thin slab continuous casting and rolling production line as claimed in claim 2, wherein the temperature of the induction heating outlet is controlled to 1050-.
7. The method for producing 800MPa steel based on a multi-mode thin slab continuous casting and rolling production line according to claim 2, wherein the finish rolling is any one of single slab rolling, semi-endless rolling and endless rolling;
when the single billet rolling is adopted in the finish rolling, double rows of phosphorus removal are adopted in the finish descaling, and the phosphorus removal pressure is more than or equal to 30 MPa;
when the semi-endless rolling or endless rolling is adopted for the finish rolling, the finish descaling adopts single-row dephosphorization, and the dephosphorization pressure is more than or equal to 30 MPa;
in the fine descaling, the distance between the dephosphorization nozzle and the slab is 60-110 mm.
8. The method for producing the 800MPa steel based on the multi-mode thin slab continuous casting and rolling production line as claimed in claim 2, wherein the finish rolling adopts 5-pass rolling, the accumulated deformation of the finish rolling is 70-80%, and the finish rolling temperature is controlled to be 820-880 ℃.
9. The method for producing the 800MPa steel based on the multi-mode thin slab continuous casting and rolling production line as claimed in claim 2, wherein the cooling speed of laminar cooling is not less than 35 ℃/s, the coiling temperature is controlled to be 560 ℃ and 660 ℃, and the obtained steel coil is air-cooled to room temperature.
10. The production method of 800MPa steel based on the multi-mode thin slab continuous casting and rolling production line of claim 2, wherein the molten steel is prepared by KR desulfurization, converter smelting, LF refining and VD refining in sequence.
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN115323285A (en) * | 2022-07-13 | 2022-11-11 | 首钢京唐钢铁联合有限责任公司 | Compartment steel plate and preparation method thereof |
| CN115747632A (en) * | 2022-09-28 | 2023-03-07 | 首钢集团有限公司 | Thin hot rolled steel and preparation method thereof |
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| CN110983180A (en) * | 2019-12-16 | 2020-04-10 | 首钢集团有限公司 | Hot-rolled high-strength steel and preparation method and application thereof |
| CN111672907A (en) * | 2020-05-12 | 2020-09-18 | 首钢集团有限公司 | Method for preparing S500MC steel coil based on multi-mode sheet billet continuous casting and rolling production line and product thereof |
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Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110983180A (en) * | 2019-12-16 | 2020-04-10 | 首钢集团有限公司 | Hot-rolled high-strength steel and preparation method and application thereof |
| CN111672907A (en) * | 2020-05-12 | 2020-09-18 | 首钢集团有限公司 | Method for preparing S500MC steel coil based on multi-mode sheet billet continuous casting and rolling production line and product thereof |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN115323285A (en) * | 2022-07-13 | 2022-11-11 | 首钢京唐钢铁联合有限责任公司 | Compartment steel plate and preparation method thereof |
| CN115747632A (en) * | 2022-09-28 | 2023-03-07 | 首钢集团有限公司 | Thin hot rolled steel and preparation method thereof |
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