CN106011618B - Method based on ESP bar strip continuous casting and rolling flow paths production DP780 steel - Google Patents
Method based on ESP bar strip continuous casting and rolling flow paths production DP780 steel Download PDFInfo
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- CN106011618B CN106011618B CN201610393922.2A CN201610393922A CN106011618B CN 106011618 B CN106011618 B CN 106011618B CN 201610393922 A CN201610393922 A CN 201610393922A CN 106011618 B CN106011618 B CN 106011618B
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/02—Ferrous alloys, e.g. steel alloys containing silicon
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
- C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
- C21D8/0221—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
- 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
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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
- C22C38/12—Ferrous alloys, e.g. steel alloys containing tungsten, tantalum, molybdenum, vanadium, or niobium
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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
- C22C38/16—Ferrous alloys, e.g. steel alloys containing copper
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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
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Abstract
The present invention provides a kind of method based on ESP bar strip continuous casting and rolling flow paths production DP780 steel, including：Raw material are selected, wherein, raw material include by mass percentage：0.06~0.20% C, 0.2~0.6% Si, 1.2~2.0% Mn, 0.1~0.5% Cr ,≤0.3% Mo, 0.02~0.05% Nb ,≤0.012% S ,≤0.015% P, 0.1%~0.5% Cu, remaining is ferro element；Raw material are subjected to converter smelting and LF stoves are smelted；Hot-strip of the molten steel to be formed by ESP producing lines generation different-thickness will be smelted from LF stoves, wherein, in ESP producing lines, the temperature of roughing outlet is 800 DEG C~860 DEG C, and the temperature of finish rolling outlet is not less than 800 DEG C；Determine ratio needed for the ferrite and martensite in hot-strip successively by secondary cooling hot-strip.It can achieve the purpose that energy conservation and environmental protection using the present invention and reduce cost.
Description
Technical Field
The invention relates to the technical field of steel, in particular to a method for producing dual-phase steel DP780 based on an ESP thin slab continuous casting and rolling process.
Background
In recent years, with the continuous decline of the steel market, steel is always in a state of little profit or no profit, so that steel manufacturers are forced to discuss the reduction of cost, and the environmental protection importance in China is further enhanced at present, so that the steel production process which discusses the reduction of cost and protects environment becomes a necessary survival path for the steel manufacturers.
Therefore, the new products developed and applied by the ESP are fully utilized, the national overall planning and industry planning are met, the relevant policy regulations of national transfer and innovation are met, the high-starting point development targets of process modernization, equipment maximization, production intensification, cyclic utilization of resources and energy, energy consumption minimization and economic benefit optimization can be met, and the method has very important significance for promoting energy conservation and emission reduction and technical progress of the steel industry and promoting enterprise transfer and upgrade, technological innovation and product structure adjustment.
The ESP (Endless Strip Production) line is a new generation of thin slab continuous casting and rolling Production line newly built by Avermedi, and has the characteristics of full-continuous Strip Production, excellent Production capacity of a single continuous casting line, large-scale Production of large-bandwidth Strip steel and high-quality Strip steel, low conversion cost from molten steel to hot rolled coils, most compact Production line process arrangement and the like because the continuous casting speed can reach 7m/min at most, a whole Strip steel can be produced in one casting process, and no head and tail are cut in the middle.
Among them, the dual phase steel has advantages of low yield ratio, high initial work hardening rate, good strength and plasticity combination, good formability and energy absorption, and has been developed into a high strength steel for stamping automobiles.
In conclusion, the invention provides a method for producing dual-phase steel DP780 based on an ESP thin slab continuous casting and rolling process, which aims to save energy, protect environment and reduce cost.
Disclosure of Invention
In view of the above problems, the present invention aims to provide a method for producing DP780 steel based on an ESP thin slab continuous casting and rolling process, which achieves the purposes of energy saving, environmental protection and cost reduction.
The invention provides a method for producing DP780 steel based on an ESP thin slab continuous casting and rolling process, which comprises the following steps: selecting raw materials, wherein the raw materials comprise the following components in percentage by mass: 0.06-0.20% of C, 0.2-0.6% of Si, 1.2-2.0% of Mn, 0.1-0.5% of Cr, less than or equal to 0.3% of Mo, 0.02-0.05% of Nb, less than or equal to 0.012% of S, less than or equal to 0.015% of P, 0.1-0.5% of Cu, and the balance of iron; performing converter smelting and LF furnace smelting on the raw materials; molten steel formed by smelting in an LF furnace is processed by an ESP production line to generate hot rolled strip steel with different thicknesses, wherein in the ESP production line, the temperature of a rough rolling outlet is 800-860 ℃, and the temperature of a finish rolling outlet is not lower than 800 ℃; sequentially determining the required proportion of ferrite and martensite in the hot-rolled strip steel through secondary cooling of the hot-rolled strip steel; firstly, cooling the hot rolled strip steel to 600-750 ℃, and then preserving heat for 2-10 s to enable the ferrite content in the hot rolled strip steel to reach the proportion required by DP780 steel; and then rapidly cooling the hot-rolled strip steel to 150-350 ℃ to enable the martensite content in the strip steel to reach the required proportion of DP780 steel.
In addition, the preferable scheme is that in an ESP production line, the temperature of a rough rolling inlet is not lower than 950 ℃, and the temperature of an induction heating outlet is 1120-1180 ℃.
Further, it is preferable that the ratio of ferrite to martensite is 5:1 in the process of sequentially determining the required ratio of ferrite to martensite in the hot-rolled strip by secondarily cooling the hot-rolled strip.
In addition, it is preferable that the thickness of the hot-rolled steel strip is 1.5mm to 6.0 mm.
Further, it is preferable that C in the raw material forms martensite required for the DP780 steel in the process of producing the DP780 steel, in order to secure the strength of the DP780 steel.
Further, it is preferable that Si in the raw material forms ferrite necessary for the DP780 steel in the process of producing the DP780 steel.
According to the technical scheme, the method for producing the DP780 steel based on the ESP thin slab continuous casting and rolling process provided by the invention has the advantages that the DP780 steel is generated by adopting the ESP process, strip steel with various thickness specifications is directly generated from continuous casting, energy is saved, the environment is protected, and the cost is reduced.
To the accomplishment of the foregoing and related ends, one or more aspects of the invention comprise the features hereinafter fully described and particularly pointed out in the claims. The following description and the annexed drawings set forth in detail certain illustrative aspects of the invention. These aspects are indicative, however, of but a few of the various ways in which the principles of the invention may be employed. Further, the present invention is intended to include all such aspects and their equivalents.
Drawings
Other objects and results of the present invention will become more apparent and more readily appreciated as the same becomes better understood by reference to the following description and appended claims, taken in conjunction with the accompanying drawings. In the drawings:
fig. 1 is a schematic flow chart of a method for producing DP780 steel based on an ESP thin slab continuous casting and rolling process according to an embodiment of the present invention.
The same reference numbers in all figures indicate similar or corresponding features or functions.
Detailed Description
In the following description, for purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of one or more embodiments. It may be evident, however, that such embodiment(s) may be practiced without these specific details.
Aiming at the problems that cost reduction is needed and the existing steel generation is environment-friendly, the invention provides the method for producing the DP780 steel based on the ESP thin slab continuous casting and rolling process, and the production and manufacturing method for producing the DP780 steel by adopting the ESP process can directly produce strip steel with various thickness specifications from continuous casting, is environment-friendly and energy-saving and can reduce the cost.
Specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings.
In order to illustrate the method for producing DP780 steel based on the ESP thin slab continuous casting and rolling process provided by the invention, FIG. 1 shows the method for producing DP780 steel based on the ESP thin slab continuous casting and rolling process according to the embodiment of the invention.
As shown in FIG. 1, the method for producing DP780 steel based on the ESP thin slab continuous casting and rolling process provided by the invention comprises the following steps:
s110: selecting raw materials, wherein the raw materials comprise the following components in percentage by mass: 0.06-0.20% of C, 0.2-0.6% of Si, 1.2-2.0% of Mn, 0.1-0.5% of Cr, less than or equal to 0.3% of Mo, 0.02-0.05% of Nb, less than or equal to 0.012% of S, less than or equal to 0.015% of P, 0.1-0.5% of Cu, and the balance of iron;
s120: performing converter smelting and LF furnace smelting on the raw materials;
s130: the molten steel smelted and formed from the LF furnace is processed by an ESP production line to generate hot rolled strip steel with different thicknesses, wherein in the ESP production line, the temperature of a rough rolling outlet is 800-860 ℃, and the temperature of a finish rolling outlet is not lower than 800 ℃;
s140: sequentially determining the required proportion of ferrite and martensite in the hot-rolled strip steel through secondary cooling of the hot-rolled strip steel; wherein,
firstly, cooling the hot rolled strip steel to 600-750 ℃, and then preserving heat for 2-10 s to enable the ferrite content in the hot rolled strip steel to reach the proportion required by DP780 steel;
and then rapidly cooling the hot-rolled strip steel to 150-350 ℃ to enable the martensite content in the strip steel to reach the required proportion of DP780 steel.
The steps are a specific method for producing the DP780 steel by adopting an ESP process, and in the invention, the key points are that the DP780 steel is produced by adopting the ESP process to obtain ferrite and martensite in a certain proportion and ensure the mechanical property of the steel, so that the production in the ESP production process must be ensured and a controlled rolling and cooling process is adopted.
In step S110, in the selection of the raw material for producing the DP780 steel, Mo is added to the raw material in an amount of 0.3% or less in order to suppress pearlite and obtain sufficient martensite while considering cost; in consideration of the strength 780MPa of the resultant DP780 steel, 0.02 to 0.05% of Nb is added to the raw material; for the requirement of the corrosion performance of the product, 0.1 to 0.5 percent of Cu is also contained in the raw material.
In the component design of the raw material, the proportion of C is 0.06-0.20%, and the proportion is mainly used for forming martensite of DP780 steel in a required amount and ensuring the strength of the DP780 steel. In consideration of properties of DP780 steel, such as weldability and the like, the C content is required to be 0.2% or less, and if C is too low (less than 0.02%), the dual phase structure is not easily obtained. C is an important element for improving the strength of the material, and the content of C can ensure the service performance of DP780 steel and reduce the production cost.
the addition of Si can change the form of austenite formed during heating in the critical zone, so that fine and uniformly distributed martensite is easily obtained, the good strengthening effect and the good matching of the strength and the ductility of the dual-phase steel are ensured, the Si is a solid solution strengthening element of ferrite, the segregation of carbon to austenite is accelerated, the gap solid solution strengthening is avoided, the generation of coarse carbides during cooling is avoided, and the extensibility of the dual-phase steel is improved.
the proportion of Mn in the raw materials is 1.0-2.0%, Mn has the effect of solid solution strengthening, can expand a gamma region, reduce gamma → α phase transition temperature, refine crystal grains, and can strongly delay pearlite transformation, thus being beneficial to bainite formation.
The proportion of Cr in the raw material is 0.1-0.5%, Cr is an austenite temperature element, and particularly the temperature range of Cr has stronger effect. Cr is a medium-strength carbide forming element, has strong affinity with C atoms, can block the diffusion of the C atoms, and has the comprehensive effect of increasing the stability of Mn, so that the hardenability of the steel is obviously improved, the pearlite transformation and the bainite transformation can be strongly delayed, and the coiling temperature range is expanded. Although Cr is a weak solid-solution strengthening element, it can increase the supercooling ability of austenite, thereby refining the structure and obtaining a strengthening effect. In addition, Cr can promote the diffusion of carbon to austenite, reduce the yield strength of ferrite and is more favorable for obtaining the low-yield-strength dual-phase steel.
The proportion of Mo in the raw material is less than or equal to 0.3 percent, Mo is a medium-strength carbide forming element, plays the roles of solid solution strengthening and precipitation strengthening in steel and has good influence on the hardenability of austenite. Mo can remarkably improve the stability of metastable austenite and inhibit the transformation of ferrite and pearlite, so that the transformation of high-temperature ferrite and pearlite in a CCT curve (Continuous cooling transformation of supercooled austenite) is remarkably shifted to the right, and the control of process parameters in actual production is facilitated. The addition of Mo can obviously reduce the sensitivity of steel grades to the controlled cooling process parameters, and ferrite and martensite dual-phase structures can be more easily obtained on a hot continuous rolling unit through a controlled rolling and controlled cooling process; and Mo is added to improve the tensile strength, reduce the yield ratio and keep the plasticity basically unchanged.
The proportion of Nb in the raw material is 0.02-0.05%, and Nb has obvious effects on grain refinement, phase transformation behavior and C enrichment in austenite. The Nb in a solid solution state retards static and dynamic recrystallization and austenite-to-ferrite transformation during hot deformation, thereby expanding the temperature range between the dynamic recrystallization termination temperature and Ac3 and facilitating rolling in the non-recrystallized zone. Nb is combined with C and N to form fine carbonitride, so that recrystallization can be delayed, ferrite grains are prevented from growing, and the steel has a strong fine-grain strengthening effect and a strong precipitation strengthening effect.
In step S120, converter and LF furnace smelting is performed according to the above-described components (step S110). That is, molten iron is smelted in a converter and then refined in an LF furnace to obtain molten steel with the components required for producing DP780 steel. The converter steelmaking (converter steelmaking) is characterized in that molten iron, scrap steel and ferroalloy are used as main raw materials, and the steelmaking process is completed in a converter by means of heat generated by physical heat of molten iron and chemical reaction among molten iron components without the help of external energy. The converter is mainly used for producing carbon steel, alloy steel and smelting copper and nickel.
An LF (ladle furnace), namely a ladle refining furnace, is a main external refining device in steel production. LF furnaces are generally referred to as refining furnaces in the steel industry, and are actually a special form of electric arc furnaces.
In the steps S130 and S140, in an ESP production line, the temperature of a casting blank entering a rough rolling inlet cannot be lower than 950 ℃, the temperature of a finish rolling rough rolling outlet is 800-860 ℃, an intermediate blank firstly enters an induction heating furnace before entering a finishing mill group, IH (the temperature of the induction heating outlet is 1120-1180 ℃, the intermediate blank exits from the induction heating furnace and enters the finishing mill group, and the temperature of the finish rolling outlet is not lower than 800 ℃, in addition, in the ESP production line, different parameters are set on a generating device according to actual requirements, and thus the medium carbon hot rolled TRIP steel with the thickness of 1.5-6.0 mm is generated.
The ratio of ferrite to martensite is controlled by controlling the cooling temperature after rolling, the ratio of ferrite to martensite in DP780 steel is 5:1 in general, and the ratio can be properly adjusted according to the strength and elongation of the steel in practical application.
And (3) cooling the hot-rolled strip steel twice to generate ferrite and martensite required by DP780 steel, and finally coiling and warehousing. Wherein, the first cooling is that the hot rolled strip steel is cooled to 600 ℃ to 750 ℃, and the temperature is kept for 2 to 10 seconds in the cooling temperature range on the layer cooling line to generate ferrite with a certain proportion; and then rapidly cooling to 150-350 ℃ to generate martensite in a certain proportion, and finally coiling and warehousing.
In an ESP production line, molten steel smelted from an LF furnace enters a continuous casting machine, a casting blank from the continuous casting machine directly enters a roughing mill set to be made into an intermediate blank (wherein the inlet temperature of the casting blank entering the roughing mill set is not lower than 950 ℃), then a wedge-shaped section at the head of the casting blank is segmented and cut off through pendulum shear, and then the casting blank enters a stacker (the stacker has the function of taking off the line at the stacker when the following equipment fails). The hot rolled strip steel directly passes through the hot rolling mill during normal rolling, then the intermediate billet enters a finishing mill group through flying shear head and tail cutting, and the hot rolled strip steel is produced from the finishing mill group (wherein the temperature of the hot rolled strip steel coming out of the finishing mill group is not lower than 800 ℃). And the hot rolled strip steel generated from the finishing mill group is cooled twice to generate ferrite and martensite required by DP780 steel, and the ferrite and the martensite are sent to a coiler through an output roller way and a pinch roll to be coiled and put in storage.
The present invention will be further illustrated by the following examples according to the above-described method of producing DP780 steel.
Example 1
Selecting raw materials, wherein the raw materials comprise the following components in percentage by mass: 0.06% of C, 0.5% of Si, 1.6% of Mn, 0.5% of Cr, 0.1% of Mo, 0.02% of Nb, 0.008% of S, 0.012% of P, 0.2% of Cu and the balance of iron element;
performing converter smelting and LF furnace smelting on the raw materials;
molten steel formed by smelting in an LF furnace is processed by an ESP production line to generate hot-rolled strip steel with the thickness of 3.0mm, wherein the temperature of a rough rolling outlet is 842 ℃ and the temperature of a finish rolling outlet is 812 ℃ in the process of processing the ESP production line;
cooling the hot-rolled strip steel to 680 ℃, and preserving heat for 4s to ensure that the ferrite content in the hot-rolled strip steel reaches the required proportion of DP780 steel; and then rapidly cooling the hot rolled strip steel to 250 ℃ to ensure that the martensite content in the hot rolled strip steel reaches the required proportion of DP780 steel.
Specification of DP780 steel: 3.0X 1250mm, yield strength: 512MPa, tensile strength: 822MPa, elongation: 19.5 percent.
Example 2
Selecting raw materials, wherein the raw materials comprise the following components in percentage by mass: 0.20% of C, 0.2% of Si, 1.2% of Mn, 0.1% of Cr, 0.3% of Mo, 0.03% of Nb, 0.012% of S, 0.015% of P, 0.2% of Cu and the balance of iron;
performing converter smelting and LF furnace smelting on the raw materials;
molten steel formed by smelting in an LF furnace is processed by an ESP production line to generate hot-rolled strip steel with the thickness of 5.0mm, wherein the temperature of a rough rolling outlet is 842 ℃ and the temperature of a finish rolling outlet is 800 ℃ in the process of processing the ESP production line;
cooling the hot rolled strip steel to 600 ℃, and preserving heat for 10s to ensure that the ferrite content in the hot rolled strip steel reaches the required proportion of DP780 steel; and then rapidly cooling the hot rolled strip steel to 150 ℃ to ensure that the martensite content in the hot rolled strip steel reaches the required proportion of DP780 steel.
Specification of DP780 steel: 5.0X 1250mm, yield strength: 532MPa, tensile strength: 722MPa, elongation: 21.5 percent.
Example 3
Selecting raw materials, wherein the raw materials comprise the following components in percentage by mass: 0.10% of C, 0.5% of Si, 1.6% of Mn, 0.5% of Cr, 0.1% of Mo, 0.02% of Nb, 0.008% of S, 0.012% of P, 0.2% of Cu and the balance of iron element;
performing converter smelting and LF furnace smelting on the raw materials;
molten steel formed by smelting in an LF furnace is processed by an ESP production line to generate hot-rolled strip steel with the thickness of 2.5mm, wherein the temperature of a rough rolling outlet is 800 ℃ and the temperature of a finish rolling outlet is 812 ℃ in the process of processing the ESP production line;
cooling the hot-rolled strip steel to 680 ℃, and preserving heat for 4s to ensure that the ferrite content in the hot-rolled strip steel reaches the required proportion of DP780 steel; and rapidly cooling the hot rolled strip to 250 ℃ to enable the martensite content in the hot rolled strip to reach the required proportion of DP780 steel.
Specification of DP780 steel: 2.5 × 1250mm, yield strength: 576MPa, tensile strength: 843MPa, elongation: 23.5 percent.
Example 4
Selecting raw materials, wherein the raw materials comprise the following components in percentage by mass: 0.06% of C, 0.6% of Si, 1.6% of Mn, 0.5% of Cr, 0.1% of Mo, 0.02% of Nb, 0.008% of S, 0.012% of P, 0.21% of Cu and the balance of iron element;
performing converter smelting and LF furnace smelting on the raw materials;
molten steel formed by smelting in an LF furnace is processed by an ESP production line to generate hot-rolled strip steel with the thickness of 4.0mm, wherein the temperature of a rough rolling outlet is 860 ℃ and the temperature of a finish rolling outlet is 820 ℃ in the process of processing the ESP production line;
cooling the hot rolled strip steel to 750 ℃, and preserving heat for 6s to ensure that the ferrite content in the hot rolled strip steel reaches the required proportion of DP780 steel; and then rapidly cooling the hot rolled strip steel to 150 ℃ to ensure that the martensite content in the hot rolled strip steel reaches the required proportion of DP780 steel.
Specification of DP780 steel: 4.0X 1250mm, yield strength: 509MPa, tensile strength: 793MPa, elongation: 18.5 percent.
Example 5
Selecting raw materials, wherein the raw materials comprise the following components in percentage by mass: 0.06% of C, 0.5% of Si, 2.0% of Mn, 0.5% of Cr, 0.1% of Mo, 0.02% of Nb, 0.008% of S, 0.012% of P, 0.25% of Cu and the balance of iron element;
performing converter smelting and LF furnace smelting on the raw materials;
molten steel formed by smelting in an LF furnace is processed by an ESP production line to generate hot-rolled strip steel with the thickness of 6.0mm, wherein the temperature of a rough rolling outlet is 950 ℃ and the temperature of a finish rolling outlet is 812 ℃ in the process of processing the ESP production line;
cooling the hot-rolled strip steel to 680 ℃, and preserving heat for 4s to ensure that the ferrite content in the hot-rolled strip steel reaches the required proportion of DP780 steel; and then rapidly cooling the hot rolled strip steel to 150 ℃ to ensure that the martensite content in the hot rolled strip steel reaches the required proportion of DP780 steel.
Specification of DP780 steel: 6.0X 1250mm, yield strength: 506MPa, tensile strength: 789MPa, elongation: 18.4 percent.
Example 6
Selecting raw materials, wherein the raw materials comprise the following components in percentage by mass: 0.06% of C, 0.5% of Si, 2.0% of Mn, 0.5% of Cr, 0.1% of Mo, 0.02% of Nb, 0.008% of S, 0.012% of P, 0.15% of Cu and the balance of iron element;
performing converter smelting and LF furnace smelting on the raw materials;
molten steel formed by smelting in an LF furnace is processed by an ESP production line to generate hot-rolled strip steel with the thickness of 3.0mm, wherein the temperature of a rough rolling outlet is 834 ℃ and the temperature of a finish rolling outlet is 812 ℃ in the process of processing the ESP production line;
cooling the hot-rolled strip steel to 680 ℃, and preserving heat for 4s to ensure that the ferrite content in the hot-rolled strip steel reaches the required proportion of DP780 steel; and then rapidly cooling the hot rolled strip steel to 250 ℃ to ensure that the martensite content in the hot rolled strip steel reaches the required proportion of DP780 steel.
Specification of DP780 steel: 3.0X 1250mm, yield strength: 556MPa, tensile strength: 833MPa, elongation: 23 percent.
Example 7
Selecting raw materials, wherein the raw materials comprise the following components in percentage by mass: 0.06% of C, 0.5% of Si, 2.0% of Mn, 0.3% of Cr, 0.1% of Mo, 0.03% of Nb, 0.008% of S, 0.012% of P, 0.3% of Cu and the balance of iron;
performing converter smelting and LF furnace smelting on the raw materials;
molten steel formed by smelting in an LF furnace is processed by an ESP production line to generate hot-rolled strip steel with the thickness of 1.5mm, wherein the temperature of a rough rolling outlet is 800 ℃ and the temperature of a finish rolling outlet is 800 ℃ in the process of processing the ESP production line;
cooling the hot-rolled strip steel to 680 ℃, and preserving heat for 8s to ensure that the ferrite content in the hot-rolled strip steel reaches the required proportion of DP780 steel; and then rapidly cooling the hot rolled strip steel to 350 ℃ to ensure that the martensite content in the hot rolled strip steel reaches the required proportion of DP780 steel.
Specification of DP780 steel: 1.5 × 1250mm, yield strength: 591MPa, tensile strength: 843MPa, elongation: 25 percent.
Example 8
Selecting raw materials, wherein the raw materials comprise the following components in percentage by mass: 0.06% of C, 0.5% of Si, 1.6% of Mn, 0.5% of Cr, 0.1% of Mo, 0.03% of Nb, 0.0012% of S, 0.015% of P, 0.1% of Cu and the balance of iron;
performing converter smelting and LF furnace smelting on the raw materials;
molten steel formed by smelting in an LF furnace is processed by an ESP production line to generate hot-rolled strip steel with the thickness of 2.5mm, wherein the temperature of a rough rolling outlet is 842 ℃ and the temperature of a finish rolling outlet is 812 ℃ in the process of processing the ESP production line;
cooling the hot-rolled strip steel to 680 ℃, and preserving heat for 4s to ensure that the ferrite content in the hot-rolled strip steel reaches the required proportion of DP780 steel; and then rapidly cooling the hot rolled strip steel to 350 ℃ to ensure that the martensite content in the hot rolled strip steel reaches the required proportion of DP780 steel.
Specification of DP780 steel: 2.5 × 1250mm, yield strength: 545MPa, tensile strength: 842MPa, elongation: 19.5 percent.
Example 9
Selecting raw materials, wherein the raw materials comprise the following components in percentage by mass: 0.06% of C, 0.5% of Si, 1.6% of Mn, 0.5% of Cr, 0.1% of Mo, 0.02% of Nb, 0.008% of S, 0.012% of P, 0.2% of Cu and the balance of iron element;
performing converter smelting and LF furnace smelting on the raw materials;
molten steel formed by smelting in an LF furnace is processed by an ESP production line to generate hot-rolled strip steel with the thickness of 4.5mm, wherein the temperature of a rough rolling inlet is 950 ℃ and the temperature of a finish rolling outlet is 800 ℃ in the process of processing the ESP production line;
cooling the hot-rolled strip steel to 680 ℃, and preserving heat for 4s to ensure that the ferrite content in the hot-rolled strip steel reaches the required proportion of DP780 steel; and then rapidly cooling the hot rolled strip steel to 250 ℃ to ensure that the martensite content in the hot rolled strip steel reaches the required proportion of DP780 steel.
Specification of DP780 steel: 4.5 × 1250mm, yield strength: 512MPa, tensile strength: 822MPa, elongation: 19.5 percent.
Example 10
Selecting raw materials, wherein the raw materials comprise the following components in percentage by mass: 0.06% of C, 0.5% of Si, 1.6% of Mn, 0.5% of Cr, 0.1% of Mo, 0.02% of Nb, 0.008% of S, 0.012% of P, 0.2% of Cu and the balance of iron element;
performing converter smelting and LF furnace smelting on the raw materials;
molten steel formed by smelting in an LF furnace is processed by an ESP production line to generate hot-rolled strip steel with the thickness of 3.5mm, wherein in the process of processing by the ESP production line, the temperature of a rough rolling inlet is 980 ℃, and the temperature of a finish rolling outlet is 850 ℃;
cooling the hot-rolled strip steel to 680 ℃, and preserving heat for 10s to ensure that the ferrite content in the hot-rolled strip steel reaches the required proportion of DP780 steel; and then rapidly cooling the hot rolled strip steel to 250 ℃ to ensure that the martensite content in the hot rolled strip steel reaches the required proportion of DP780 steel.
Specification of DP780 steel: 3.5 × 1250mm, yield strength: 523MPa, tensile strength: 806MPa, elongation: 20 percent.
Example 11
Selecting raw materials, wherein the raw materials comprise the following components in percentage by mass: 0.06% of C, 0.5% of Si, 1.6% of Mn, 0.5% of Cr, 0.1% of Mo, 0.02% of Nb, 0.008% of S, 0.012% of P, 0.2% of Cu and the balance of iron element;
performing converter smelting and LF furnace smelting on the raw materials;
molten steel formed by smelting in an LF furnace is processed by an ESP production line to generate hot-rolled strip steel with the thickness of 2.5mm, wherein the temperature of a rough rolling outlet is 850 ℃ and the temperature of a finish rolling outlet is 800 ℃ in the process of processing the ESP production line;
cooling the hot rolled strip steel to 600 ℃, and preserving heat for 4s to ensure that the ferrite content in the hot rolled strip steel reaches the required proportion of DP780 steel; and then rapidly cooling the hot rolled strip steel to 250 ℃ to ensure that the martensite content in the hot rolled strip steel reaches the required proportion of DP780 steel.
Specification of DP780 steel: 2.5.0X 1250mm, yield strength: 517MPa, tensile strength: 807MPa, elongation: 21 percent.
Example 12
Selecting raw materials, wherein the raw materials comprise the following components in percentage by mass: 0.06% of C, 0.5% of Si, 1.6% of Mn, 0.5% of Cr, 0.1% of Mo, 0.02% of Nb, 0.008% of S, 0.012% of P, 0.2% of Cu and the balance of iron element;
performing converter smelting and LF furnace smelting on the raw materials;
molten steel formed by smelting in an LF furnace is processed by an ESP production line to generate hot-rolled strip steel with the thickness of 3.0mm, wherein the temperature of a rough rolling outlet is 842 ℃ and the temperature of a finish rolling outlet is 800 ℃ in the process of processing the ESP production line;
cooling the hot rolled strip steel to 750 ℃, and preserving heat for 10s to ensure that the ferrite content in the hot rolled strip steel reaches the required proportion of DP780 steel; and then rapidly cooling the hot rolled strip steel to 250 ℃ to ensure that the martensite content in the hot rolled strip steel reaches the required proportion of DP780 steel.
Specification of DP780 steel: 3.0X 1250mm, yield strength: 566MPa, tensile Strength: 816MPa, elongation: 22.3 percent.
Example 13
Selecting raw materials, wherein the raw materials comprise the following components in percentage by mass: 0.06% of C, 0.5% of Si, 1.6% of Mn, 0.5% of Cr, 0.1% of Mo, 0.02% of Nb, 0.008% of S, 0.012% of P, 0.2% of Cu and the balance of iron element;
performing converter smelting and LF furnace smelting on the raw materials;
molten steel formed by smelting in an LF furnace is processed by an ESP production line to generate hot-rolled strip steel with the thickness of 4.5mm, wherein the temperature of a rough rolling outlet is 860 ℃ and the temperature of a finish rolling outlet is 800 ℃ in the process of processing the ESP production line;
cooling the hot rolled strip steel to 600 ℃, and preserving heat for 2s to ensure that the ferrite content in the hot rolled strip steel reaches the required proportion of DP780 steel; and then rapidly cooling the hot rolled strip steel to 250 ℃ to ensure that the martensite content in the hot rolled strip steel reaches the required proportion of DP780 steel.
Specification of DP780 steel: 4.5 × 1250mm, yield strength: 534MPa, tensile strength: 807MPa, elongation: 21 percent.
Example 14
Selecting raw materials, wherein the raw materials comprise the following components in percentage by mass: 0.06% of C, 0.5% of Si, 1.6% of Mn, 0.5% of Cr, 0.1% of Mo, 0.02% of Nb, 0.008% of S, 0.012% of P, 0.2% of Cu and the balance of iron element;
performing converter smelting and LF furnace smelting on the raw materials;
molten steel formed by smelting in an LF furnace is processed by an ESP production line to generate hot rolled strip steel with the thickness of 6.0mm, wherein the temperature of a rough rolling outlet is 841 ℃ and the temperature of a finish rolling outlet is 800 ℃ in the process of processing the ESP production line;
cooling the hot rolled strip steel to 600 ℃, and preserving heat for 4s to ensure that the ferrite content in the hot rolled strip steel reaches the required proportion of DP780 steel; and then rapidly cooling the hot rolled strip steel to 350 ℃ to ensure that the martensite content in the hot rolled strip steel reaches the required proportion of DP780 steel.
Specification of DP780 steel: 6.0X 1250mm, yield strength: 509MPa, tensile strength: 792MPa, elongation: 25 percent.
It should be noted that the DP780 steel produced in the above examples has a negligible variation in thickness, and both the yield strength and the tensile strength have a variation of about 30MPa, which is described herein.
According to the method for producing the DP780 steel based on the ESP thin slab continuous casting and rolling process, the DP780 steel is produced by adopting the ESP process, strip steel with various thickness specifications is directly produced from continuous casting, and the method not only can save energy and protect environment, but also can reduce cost.
The method for producing DP780 steel based on the ESP thin slab continuous casting and rolling process proposed according to the present invention is described above by way of example with reference to the accompanying drawings. However, it will be appreciated by those skilled in the art that various modifications may be made to the method of producing DP780 steel based on the ESP thin slab continuous casting and rolling process set forth above without departing from the scope of the invention. Therefore, the scope of the present invention should be determined by the contents of the appended claims.
Claims (6)
1. A method for producing DP780 steel based on an ESP thin slab continuous casting and rolling process comprises the following steps:
selecting raw materials, wherein the raw materials comprise the following components in percentage by mass: 0.06-0.20% of C, 0.2-0.6% of Si, 1.2-2.0% of Mn, 0.1-0.5% of Cr, less than or equal to 0.3% of Mo, 0.02-0.05% of Nb, less than or equal to 0.012% of S, less than or equal to 0.015% of P, 0.1-0.5% of Cu, and the balance of iron;
carrying out converter smelting and LF furnace smelting on the raw materials;
hot-rolled strip steel with different thicknesses is generated from molten steel smelted from the LF furnace through an ESP production line, wherein in the ESP production line, the temperature of a rough rolling outlet is 800-860 ℃, the temperature of a finish rolling outlet is not lower than 800 ℃, and the temperature of an induction heating outlet is 1120-1180 ℃;
sequentially determining the required proportion of ferrite and martensite in the hot-rolled strip steel through secondary cooling of the hot-rolled strip steel; wherein,
firstly, cooling the hot rolled strip steel to 600-750 ℃, and then preserving heat for 2-10 s to enable the ferrite content in the hot rolled strip steel to reach the proportion required by DP780 steel;
and then rapidly cooling the hot-rolled strip steel to 150-350 ℃ so that the martensite content in the hot-rolled strip steel reaches the required proportion of DP780 steel.
2. The method for producing DP780 steel based on ESP thin slab continuous casting and rolling process as claimed in claim 1,
in the ESP production line, the temperature of a rough rolling inlet is not lower than 950 ℃.
3. The method for producing DP780 steel based on ESP thin slab continuous casting and rolling process as claimed in claim 1,
in the process of sequentially determining the required ratio of ferrite to martensite in the hot-rolled strip by secondarily cooling the hot-rolled strip, the ratio of ferrite to martensite is 5: 1.
4. The method for producing DP780 steel based on ESP thin slab continuous casting and rolling process as claimed in claim 1,
the thickness of the hot-rolled strip steel is 1.5 mm-6.0 mm.
5. The method for producing DP780 steel based on ESP thin slab continuous casting and rolling process as claimed in claim 1,
in the process of producing the DP780 steel, C in the raw material forms martensite required for the DP780 steel to secure the strength of the DP780 steel.
6. The method for producing DP780 steel based on ESP thin slab continuous casting and rolling process as claimed in claim 1,
during the production of DP780 steel, Si in the raw material forms ferrite required for DP780 steel.
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| CN106834886B (en) * | 2016-12-30 | 2018-11-27 | 日照宝华新材料有限公司 | Method based on ESP bar strip continuous casting and rolling flow path production thin gauge RE65Mn steel |
| CN106834885B (en) * | 2016-12-30 | 2018-11-06 | 日照钢铁控股集团有限公司 | The method for producing Thin Specs Q345 Series Steels based on ESP bar strip continuous casting and rolling flow paths |
| CN106801195B (en) * | 2016-12-30 | 2018-11-27 | 日照宝华新材料有限公司 | Method based on ESP bar strip continuous casting and rolling flow path production thin gauge RE75Cr1 steel |
| CN106756508B (en) * | 2016-12-30 | 2018-11-06 | 日照钢铁控股集团有限公司 | The method for producing Thin Specs REH380LA steel based on ESP bar strip continuous casting and rolling flow paths |
| CN107641699B (en) * | 2017-09-20 | 2019-06-18 | 武汉钢铁有限公司 | Method based on CSP process production thin gauge hot rolling DP780 steel |
| CN107739799A (en) * | 2017-09-30 | 2018-02-27 | 日照宝华新材料有限公司 | Based on the method that SPFH590 steel is produced completely without head sheet continuous casting and rolling |
| CN109055867B (en) * | 2018-08-30 | 2021-06-29 | 日照钢铁控股集团有限公司 | Method for producing high-hole-expansion hot-dip galvanized plate with tensile strength of 540MPa |
| CN110004362B (en) * | 2019-04-01 | 2021-06-18 | 山东钢铁集团日照有限公司 | Production method for improving yield ratio and hole expanding performance of cold-rolled DP780 steel |
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