CN115404401A - 700 MPa-grade CSP short-process hot-rolled high-strength structural steel and manufacturing method thereof - Google Patents
700 MPa-grade CSP short-process hot-rolled high-strength structural steel and manufacturing method thereof Download PDFInfo
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- 238000000034 method Methods 0.000 title claims abstract description 33
- 229910000746 Structural steel Inorganic materials 0.000 title claims abstract description 18
- 238000004519 manufacturing process Methods 0.000 title claims abstract description 17
- 238000005096 rolling process Methods 0.000 claims abstract description 38
- 229910000831 Steel Inorganic materials 0.000 claims abstract description 32
- 239000010959 steel Substances 0.000 claims abstract description 32
- 239000000126 substance Substances 0.000 claims abstract description 16
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- 229910052785 arsenic Inorganic materials 0.000 claims abstract description 12
- 229910052757 nitrogen Inorganic materials 0.000 claims abstract description 12
- 239000012535 impurity Substances 0.000 claims abstract description 10
- 229910052742 iron Inorganic materials 0.000 claims abstract description 10
- 229910045601 alloy Inorganic materials 0.000 claims abstract description 7
- 239000000956 alloy Substances 0.000 claims abstract description 7
- 238000001816 cooling Methods 0.000 claims description 14
- 238000010438 heat treatment Methods 0.000 claims description 10
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 8
- 238000005266 casting Methods 0.000 claims description 7
- 238000009749 continuous casting Methods 0.000 claims description 6
- 238000009847 ladle furnace Methods 0.000 claims description 5
- 238000002791 soaking Methods 0.000 claims description 5
- 238000003723 Smelting Methods 0.000 claims description 4
- 238000007670 refining Methods 0.000 claims description 4
- 229910052717 sulfur Inorganic materials 0.000 claims description 4
- 238000002360 preparation method Methods 0.000 claims description 2
- 238000005452 bending Methods 0.000 abstract description 3
- 238000003466 welding Methods 0.000 abstract description 2
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 14
- 239000000463 material Substances 0.000 description 10
- 230000000694 effects Effects 0.000 description 7
- 239000010936 titanium Substances 0.000 description 7
- 238000001556 precipitation Methods 0.000 description 6
- 238000005728 strengthening Methods 0.000 description 6
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- 229910052799 carbon Inorganic materials 0.000 description 5
- 239000011572 manganese Substances 0.000 description 5
- 229910000859 α-Fe Inorganic materials 0.000 description 5
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 4
- PWHULOQIROXLJO-UHFFFAOYSA-N Manganese Chemical compound [Mn] PWHULOQIROXLJO-UHFFFAOYSA-N 0.000 description 4
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 4
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 description 4
- 229910052748 manganese Inorganic materials 0.000 description 4
- 229910052710 silicon Inorganic materials 0.000 description 4
- 239000010703 silicon Substances 0.000 description 4
- 229910052719 titanium Inorganic materials 0.000 description 4
- OAICVXFJPJFONN-UHFFFAOYSA-N Phosphorus Chemical compound [P] OAICVXFJPJFONN-UHFFFAOYSA-N 0.000 description 3
- 229910001566 austenite Inorganic materials 0.000 description 3
- 239000000203 mixture Substances 0.000 description 3
- 239000011574 phosphorus Substances 0.000 description 3
- 230000009466 transformation Effects 0.000 description 3
- NINIDFKCEFEMDL-UHFFFAOYSA-N Sulfur Chemical compound [S] NINIDFKCEFEMDL-UHFFFAOYSA-N 0.000 description 2
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 2
- 229910052782 aluminium Inorganic materials 0.000 description 2
- RQNWIZPPADIBDY-UHFFFAOYSA-N arsenic atom Chemical compound [As] RQNWIZPPADIBDY-UHFFFAOYSA-N 0.000 description 2
- 238000006243 chemical reaction Methods 0.000 description 2
- 238000013461 design Methods 0.000 description 2
- 239000011593 sulfur Substances 0.000 description 2
- 238000012360 testing method Methods 0.000 description 2
- 229910018072 Al 2 O 3 Inorganic materials 0.000 description 1
- 229910001208 Crucible steel Inorganic materials 0.000 description 1
- 229910000742 Microalloyed steel Inorganic materials 0.000 description 1
- 229910004283 SiO 4 Inorganic materials 0.000 description 1
- 238000005275 alloying Methods 0.000 description 1
- 229910001563 bainite Inorganic materials 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 229910052802 copper Inorganic materials 0.000 description 1
- 238000005336 cracking Methods 0.000 description 1
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- 238000011161 development Methods 0.000 description 1
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- 229910052758 niobium Inorganic materials 0.000 description 1
- 230000006911 nucleation Effects 0.000 description 1
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- 238000012545 processing Methods 0.000 description 1
- 238000012827 research and development Methods 0.000 description 1
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- 238000004781 supercooling Methods 0.000 description 1
- 229910052720 vanadium Inorganic materials 0.000 description 1
Images
Classifications
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/02—Ferrous alloys, e.g. steel alloys containing silicon
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- 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
-
- 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
-
- 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
-
- 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
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
- C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
- C21D8/0221—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the working steps
- C21D8/0226—Hot rolling
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
- C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
- C21D8/0247—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the heat treatment
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C33/00—Making ferrous alloys
- C22C33/04—Making ferrous alloys by melting
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/04—Ferrous alloys, e.g. steel alloys containing manganese
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/06—Ferrous alloys, e.g. steel alloys containing aluminium
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/14—Ferrous alloys, e.g. steel alloys containing titanium or zirconium
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D2211/00—Microstructure comprising significant phases
- C21D2211/002—Bainite
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D2211/00—Microstructure comprising significant phases
- C21D2211/005—Ferrite
Abstract
The invention discloses 700MPa CSP short-process hot-rolled high-strength structural steel and a manufacturing method thereof, wherein the structural steel comprises the following chemical components in percentage by weight: 0.045 to 0.069%, si: less than or equal to 0.20 percent, mn:0.9 to 1.3%, P: less than or equal to 0.012 percent, S: less than or equal to 0.003 percent, ti:0.11 to 0.20%, als:0.02 to 0.08 percent of Fe, less than or equal to 0.012 percent of As, less than or equal to 0.006 percent of N, and the balance of Fe and inevitable impurities. The thin steel plate strip with the yield strength of more than or equal to 700MPa level produced by the invention has the advantages of low process cost and alloy cost, tensile strength of more than or equal to 750MPa, elongation of more than or equal to 16 percent, higher extension plasticity, and extremely high product strength-plasticity product, and can meet various application requirements and application environments of users such as rolling, bending and other various forming processes, welding and the like.
Description
Technical Field
The invention relates to the field of microalloyed steel manufacturing, in particular to 700 MPa-grade CSP short-process hot-rolled low-cost high-strength structural steel and a manufacturing method thereof.
Background
How to realize the lightweight structure by improving the strength of the steel plate so as to achieve the effects of reducing consumption and energy, reducing the labor intensity of workers and the like becomes the necessity of the development of modern steel materials. In general structural steels, the level of plasticity tends to decrease as the strength of the material increases. The plasticity represents the deformation capability of the material, and the excessively low plasticity directly influences the forming of the structure of the user part, so that the problems of cracking and the like are easily caused, and the material is unusable. How to solve the problem of the pair of spears with strength and plasticity also becomes a difficult point for the research and development of steel material varieties.
High-strength steel with yield strength of 700MPa level is researched and manufactured in organizations and enterprises at home and abroad. A weather-resistant high-strength steel plate with excellent bending workability and a manufacturing method thereof (patent No. CN 1639371A) published abroad by Nippon iron works, a manufacturing method of 700MPa grade F/B high-strength strip steel developed domestically by northeast university (patent No. CN 1757783A), a high-strength cold-forming hot continuous rolling steel plate developed by Baoshan iron and Steel works Limited company and a manufacturing method thereof (patent No. CN 101153371A) have yield strength reaching 700MPa grade, but the whole production cost is high due to the fact that the design components contain precious alloys such as Cu, ni, V, mo, nb and the like. How to develop a low-alloy high-strength steel material which has high strength and high plasticity and simultaneously has economical efficiency and practicability has great difficulty.
Disclosure of Invention
The invention aims to solve the defects of the background technology, and provides hot-rolled high-strength steel with yield strength of 700MPa and a manufacturing method thereof, so that on one hand, high strength (yield strength is more than or equal to 700MPa, and tensile strength is more than or equal to 750 MPa) is ensured, high plasticity (elongation after fracture is more than or equal to 16%) is realized, and on the basis, low-cost design and production are realized.
The technical scheme of the invention is as follows: a700 MPa CSP short-process hot-rolled high-strength structural steel is characterized by comprising the following chemical components in percentage by weight,
c:0.045 to 0.069%, si: less than or equal to 0.20 percent, mn:0.9 to 1.3%, P: less than or equal to 0.012 percent, S: less than or equal to 0.003 percent, ti:0.11 to 0.20%, als:0.02 to 0.08 percent of Fe, less than or equal to 0.012 percent of As, less than or equal to 0.006 percent of N, and the balance of Fe and inevitable impurities.
Preferably, the chemical components comprise the following chemical components in percentage by weight,
c: 0.048-0.050%, si: less than or equal to 0.15 percent, mn:1.10 to 1.13%, P: less than or equal to 0.010 percent, S: less than or equal to 0.003 percent, ti:0.160 to 0.165%, als:0.035 to 0.05 percent of Fe, less than or equal to 0.0036 percent of As, less than or equal to 0.005 percent of N, and the balance of Fe and inevitable impurities.
Preferably, the 700MPa CSP short-process hot-rolled high-strength structural steel has the thickness of 1.2-4.5 mm, the yield strength of more than or equal to 700MPa, the tensile strength of more than or equal to 750MPa and the elongation of more than or equal to 16%.
The invention also provides a preparation method of the 700MPa CSP short-process hot-rolled high-strength structural steel, which is characterized by comprising the following steps of:
1) Smelting in a converter, then refining in an LF furnace, and controlling the chemical components and weight percentage of molten steel as C:0.045 to 0.069%, si: less than or equal to 0.20 percent, mn:0.9 to 1.3%, P: less than or equal to 0.012 percent, S: less than or equal to 0.003 percent, ti:0.11 to 0.20%, als:0.02 to 0.08 percent of Fe, less than or equal to 0.012 percent of As, less than or equal to 0.006 percent of N, and the balance of Fe and inevitable impurities;
2) And then, carrying out thin slab continuous casting and rolling production on the molten steel: the thickness of the cast billet is 60-85 mm; heating the casting blank in a soaking furnace, wherein the heating temperature is controlled to be 1180-1230 ℃; rolling in a 7-rack finishing mill, wherein the starting rolling temperature of finish rolling is more than or equal to 1100 ℃, the reduction rate of the first three passes is more than or equal to 50%, the pass temperature is more than or equal to 1050 ℃, the reduction rate of the F4 pass is more than or equal to 40%, the reduction rate of the F5 pass is more than or equal to 35%, constant-speed rolling is adopted according to the thickness specification, the rolling speed is controlled to be 3.0-12.0 m/s, the final rolling temperature is controlled to be 870-930 ℃, and the rolling thickness is 1.2-4.5 mm;
3) Laminar cooling: the water cooling speed is 70-120 ℃/s, the temperature is cooled to 650-700 ℃, and then the temperature is cooled to 590-650 ℃ according to the water cooling speed of less than or equal to 10 ℃/s for coiling.
Preferably, in the step 1), the chemical components of the molten steel and the weight percentage of C: 0.048-0.050%, si: less than or equal to 0.15 percent, mn:1.10 to 1.13%, P: less than or equal to 0.010 percent, S: less than or equal to 0.003 percent, ti:0.160 to 0.165%, als:0.035 to 0.05 percent of the total weight of the alloy, less than or equal to 0.0036 percent of As, less than or equal to 0.005 percent of N, and the balance of Fe and inevitable impurities.
Preferably, in the step 2), the casting blank is heated in a soaking furnace, and the heating temperature is controlled to be 1220-1230 ℃.
Preferably, in the step 2), constant-speed rolling is adopted according to the thickness specification, the rolling speed is controlled to be 11-12m/s, and the finishing temperature is controlled to be 900-910 ℃.
Preferably, in the step 3), the temperature is cooled to 690-700 ℃, and then the cooled temperature is cooled to 640-650 ℃ at the water cooling speed of less than or equal to 10 ℃/s for coiling.
The chemical components of the present invention are explained below:
c, carbon C: carbon is the most economical strengthening element. However, if the carbon content is more than 0.07%, good formability of the material cannot be satisfied, and at the same time, peritectic reaction of molten steel during casting may occur, increasing the risk of continuous casting breakout, and too high carbon content may affect weldability of the steel. Therefore, the carbon content is limited to the range of 0.045 to 0.069%.
Silicon Si: silicon purifies ferrite and prevents the formation of coarse carbides during cooling, but silicon also readily forms Fe 2 SiO 4 And a eutectoid product is formed on the surface of the steel billet and FeO and is solidified into an anchor structure, so that the FeO is difficult to remove, and the final surface quality is influenced. Therefore, the silicon content is limited to the range of 0.20% or less.
Manganese Mn: manganese is the most effective element for improving the strength and toughness, and can effectively delay pearlite transformation. If the content is less than 0.9 percent, the strength requirement of the material cannot be met; however, since the addition of excessive manganese also easily causes peritectic reaction of molten steel and causes quality problems such as continuous casting cracks, the manganese content is limited to a range of 0.9 to 1.3%.
Titanium Ti: the precipitation strengthening effect of titanium is outstanding, the titanium precipitation strengthening effect is an economic and effective element for ensuring the strength of steel, and the titanium content range of the invention is designed to be 0.11-0.20%.
Phosphorus P: phosphorus tends to cause center segregation, which affects formability. In the invention, the content of phosphorus is controlled to be less than or equal to 0.012 percent.
Aluminum Als: as an effective deoxidizer in the smelting process, simultaneously has a certain grain refining effect, improves the strength of steel, but is easy to form Al 2 O 3 And (4) inclusion. In the invention, the content of acid-soluble aluminum is controlled to be 0.02 to 0.08 percent
Arsenic As: the toughness and plasticity of the material can be greatly reduced, and the arsenic content is strictly controlled to be less than or equal to 0.012 percent in the invention.
Sulfur S, nitrogen N: easily combined with Ti in steel, influences the strengthening effect of Ti and greatly influences the plasticity of steel, and in the invention, the sulfur is controlled to be less than or equal to 0.003 percent and the nitrogen is controlled to be less than or equal to 0.006 percent.
In the present invention, noble alloying elements such as Nb, cu, ni, mo, and the like are not added from the viewpoint of improving the formability of the material and the economy, except for limiting the ranges of the above chemical components.
The control of the main process is explained below.
The CSP production line is characterized in that a continuous casting billet directly enters a heating furnace for heating after being cast and cut, is rolled by a 7-pass rolling mill after being discharged from the furnace for dephosphorization, and is coiled after being cooled by laminar flow; compared with the conventional process, the time and energy consumption of the whole production process are greatly reduced, and the method has the characteristic of environmental protection.
And selecting a blank thickness of 62-85mm for rolling according to different finished product thicknesses by combining the load condition of a production line rolling mill.
The casting blank is heated and insulated at 1180-1230 ℃, and the temperature can ensure that more alloy elements are dissolved into austenite in a solid mode and are separated out at a subsequent low-temperature stage to achieve a larger strengthening effect.
The finishing rolling temperature is controlled to be 870-930 ℃, and the austenite can obtain larger deformation storage energy through the deformation in the temperature range, so that dynamic conditions and nucleation points are provided for subsequent ferrite phase transformation and precipitation.
The intermediate temperature is controlled between 650 ℃ and 700 ℃, and the austenite supercooling degree is increased by rapidly cooling to the temperature range after rolling, so that the ferrite transformation is facilitated, and a foundation is provided for subsequent interphase precipitation and dispersion precipitation.
The coiling temperature is controlled at 590-650 ℃, and the temperature interval can separate out the nanometer precipitated phase to the maximum extent so as to achieve the precipitation strengthening effect.
The rolling speed is controlled to be 3.0-12.0 m/s for constant-speed rolling according to the thickness of a finished product, so that the stability of the coil-feeding process and the stability of the overall performance are ensured.
The invention has the beneficial effects that:
compared with the prior art, the process cost and the alloy cost of the produced thin steel plate strip with the yield strength of more than or equal to 700MPa are low, the tensile strength is more than or equal to 750MPa, the elongation is more than or equal to 16%, the product has higher extension plasticity, the product has extremely high product of strength and elongation (up to 15.6 GPa%), the product can be applied to the field of high-strength structural members with higher forming requirements, and various forming processes such as rolling and bending, various application requirements such as welding and the like and application environments can be met.
Drawings
FIG. 1 is a metallographic structure diagram of 700MPa CSP short-process hot-rolled high-strength structural steel.
Detailed Description
The following specific examples further illustrate the invention in detail. Table 1 is a list of chemical compositions for each example of the invention; table 2 is a table of the main process parameters of each embodiment of the present invention; the embodiments of the invention are produced according to the following steps:
1) Smelting in a converter, then refining in an LF (ladle furnace), and controlling the chemical components and the weight percentage of molten steel as C:0.045 to 0.069%, si: less than or equal to 0.20 percent, mn:0.9 to 1.3%, P: less than or equal to 0.012%, S: less than or equal to 0.003 percent, ti:0.11 to 0.20%, als:0.02 to 0.08 percent of Fe, less than or equal to 0.012 percent of As, less than or equal to 0.006 percent of N, and the balance of Fe and inevitable impurities;
2) And then, carrying out thin slab continuous casting and rolling production on the molten steel: the thickness of the cast billet is 60-85 mm; heating the casting blank in a soaking furnace, wherein the heating temperature is controlled to be 1180-1230 ℃; rolling in a 7-stand finishing mill, wherein the starting temperature of finish rolling is more than or equal to 1100 ℃, the reduction rate of the first three passes is more than or equal to 50%, the pass temperature is more than or equal to 1050 ℃, the reduction rate of the F4 pass is more than or equal to 40%, the reduction rate of the F5 pass is more than or equal to 35%, constant-speed rolling is adopted according to the thickness specification, the rolling speed is controlled to be 3.0-12.0 m/s, the final rolling temperature is controlled to be 870-930 ℃, and the rolling thickness is 1.2-4.5 mm;
3) Laminar cooling: the water cooling speed is 70-120 ℃/s, the steel is cooled to the intermediate cooling temperature of 650-700 ℃, and then the steel is cooled to 590-650 ℃ at the water cooling speed of less than or equal to 10 ℃/s for coiling.
The chemical composition list of examples 1-5 is shown in table 1 below, the main process parameters of examples 1-5 are shown in table 2 below, and the mechanical property test results of the products obtained in examples 1-5 are shown in table 3 below.
Table 1 chemical composition list of each example of the invention
Table 2 list of main process parameters of various embodiments of the present invention
TABLE 3 mechanical Property test results List of the various embodiments of the present invention
As can be seen from Table 3, the final products obtained in examples 1-5 have yield strength of not less than 700MPa, tensile strength of not less than 750MPa, elongation of not less than 16%, and product of strength and elongation of up to 15.64 GPa. The metallographic structure of the product is shown in figure 1, the structure type is ferrite or ferrite plus a small amount of bainite, and the structure type has good plasticity, so that the product can meet the requirement of the subsequent processing process.
Claims (8)
1. A700 MPa CSP short-process hot-rolled high-strength structural steel is characterized by comprising the following chemical components in percentage by weight,
c:0.045 to 0.069%, si: less than or equal to 0.20 percent, mn:0.9 to 1.3%, P: less than or equal to 0.012 percent, S: less than or equal to 0.003 percent, ti:0.11 to 0.20%, als:0.02 to 0.08 percent of Fe, less than or equal to 0.012 percent of As, less than or equal to 0.006 percent of N, and the balance of Fe and inevitable impurities.
2. The 700MPa CSP short run hot rolled high strength structural steel according to claim 1, comprising the following chemical components in weight percent,
c: 0.048-0.050%, si: less than or equal to 0.15 percent, mn:1.10 to 1.13%, P: less than or equal to 0.010 percent, S: less than or equal to 0.003 percent, ti:0.160 to 0.165%, als:0.035 to 0.05 percent of the total weight of the alloy, less than or equal to 0.0036 percent of As, less than or equal to 0.005 percent of N, and the balance of Fe and inevitable impurities.
3. The 700MPa CSP short process hot-rolled high-strength structural steel as claimed in claim 1, wherein the 700MPa CSP short process hot-rolled high-strength structural steel has a thickness of 1.2-4.5 mm, a yield strength of not less than 700MPa, a tensile strength of not less than 750MPa, and an elongation of not less than 16%.
4. A preparation method of 700 MPa-grade CSP short-process hot-rolled high-strength structural steel is characterized by comprising the following steps:
1) Smelting in a converter, then refining in an LF (ladle furnace), and controlling the chemical components and the weight percentage of molten steel as C:0.045 to 0.069%, si: less than or equal to 0.20 percent, mn:0.9 to 1.3%, P: less than or equal to 0.012 percent, S: less than or equal to 0.003 percent, ti:0.11 to 0.20%, als:0.02 to 0.08 percent of Fe, less than or equal to 0.012 percent of As, less than or equal to 0.006 percent of N, and the balance of Fe and inevitable impurities;
2) And then, carrying out thin slab continuous casting and rolling production on the molten steel: the thickness of the cast billet is 60-85 mm; heating the casting blank in a soaking furnace, wherein the heating temperature is controlled to be 1180-1230 ℃; rolling in a 7-rack finishing mill, wherein the starting rolling temperature of finish rolling is more than or equal to 1100 ℃, the reduction rate of the first three passes is more than or equal to 50%, the pass temperature is more than or equal to 1050 ℃, the reduction rate of the F4 pass is more than or equal to 40%, the reduction rate of the F5 pass is more than or equal to 35%, constant-speed rolling is adopted according to the thickness specification, the rolling speed is controlled to be 3.0-12.0 m/s, the final rolling temperature is controlled to be 870-930 ℃, and the rolling thickness is 1.2-4.5 mm;
3) Laminar cooling: the water cooling speed is 70-120 ℃/s, the temperature is cooled to 650-700 ℃, and then the temperature is cooled to 590-650 ℃ according to the water cooling speed of less than or equal to 10 ℃/s for coiling.
5. The method for preparing 700MPa CSP short-process hot-rolled high-strength structural steel according to claim 4, characterized in that in the step 1), the chemical components of molten steel and the weight percentage of C: 0.048-0.050%, si: less than or equal to 0.15 percent, mn:1.10 to 1.13%, P: less than or equal to 0.010%, S: less than or equal to 0.003 percent, ti:0.160 to 0.165%, als:0.035 to 0.05 percent of Fe, less than or equal to 0.0036 percent of As, less than or equal to 0.005 percent of N, and the balance of Fe and inevitable impurities.
6. The method for preparing 700MPa CSP short-process hot-rolled high-strength structural steel as claimed in claim 4, wherein in the step 2), the casting blank is heated in a soaking furnace, and the heating temperature is controlled to be 1220-1230 ℃.
7. The method for preparing 700MPa CSP short-process hot-rolled high-strength structural steel according to claim 4, wherein in the step 2), constant-speed rolling is adopted according to the thickness specification, the rolling speed is controlled to be 11-12m/s, and the final rolling temperature is controlled to be 900-910 ℃.
8. The method for preparing 700MPa CSP short-process hot-rolled high-strength structural steel as claimed in claim 4, wherein in the step 3), the temperature is cooled to 690-700 ℃, and then the steel is cooled to 640-650 ℃ according to the water cooling speed of less than or equal to 10 ℃/s for coiling.
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| CN102965573A (en) * | 2012-11-30 | 2013-03-13 | 武汉钢铁(集团)公司 | High-strength thin steel plate produced by CSP (cast steel plate) process and preparation method of plate |
| CN104342601A (en) * | 2014-11-17 | 2015-02-11 | 武汉钢铁(集团)公司 | Ti-containing low-manganese and low-silicon hot-rolled steel with Rel being greater than or equal to 400MPa and production method adopting CSP (cast steel plate) |
| CN114345938A (en) * | 2022-01-04 | 2022-04-15 | 湖南华菱涟源钢铁有限公司 | Method for producing high-strength steel with yield strength of 700MPa grade based on short process and low cost |
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Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102965573A (en) * | 2012-11-30 | 2013-03-13 | 武汉钢铁(集团)公司 | High-strength thin steel plate produced by CSP (cast steel plate) process and preparation method of plate |
| CN104342601A (en) * | 2014-11-17 | 2015-02-11 | 武汉钢铁(集团)公司 | Ti-containing low-manganese and low-silicon hot-rolled steel with Rel being greater than or equal to 400MPa and production method adopting CSP (cast steel plate) |
| CN114345938A (en) * | 2022-01-04 | 2022-04-15 | 湖南华菱涟源钢铁有限公司 | Method for producing high-strength steel with yield strength of 700MPa grade based on short process and low cost |
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