CN114000064A - Ultrahigh-strength hot-rolled steel strip with thickness less than 4mm and production method thereof - Google Patents
Ultrahigh-strength hot-rolled steel strip with thickness less than 4mm and production method thereof Download PDFInfo
- Publication number
- CN114000064A CN114000064A CN202111274414.XA CN202111274414A CN114000064A CN 114000064 A CN114000064 A CN 114000064A CN 202111274414 A CN202111274414 A CN 202111274414A CN 114000064 A CN114000064 A CN 114000064A
- Authority
- CN
- China
- Prior art keywords
- equal
- less
- steel strip
- rolled steel
- thickness
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
- 229910000831 Steel Inorganic materials 0.000 title claims abstract description 98
- 239000010959 steel Substances 0.000 title claims abstract description 98
- 238000004519 manufacturing process Methods 0.000 title claims abstract description 17
- 238000000034 method Methods 0.000 claims abstract description 50
- 238000001816 cooling Methods 0.000 claims abstract description 35
- 238000007670 refining Methods 0.000 claims abstract description 17
- 238000009749 continuous casting Methods 0.000 claims abstract description 14
- 238000003723 Smelting Methods 0.000 claims abstract description 7
- 238000006477 desulfuration reaction Methods 0.000 claims abstract description 7
- 230000023556 desulfurization Effects 0.000 claims abstract description 7
- 238000005098 hot rolling Methods 0.000 claims abstract description 7
- 239000012535 impurity Substances 0.000 claims abstract description 7
- OYPRJOBELJOOCE-UHFFFAOYSA-N Calcium Chemical compound [Ca] OYPRJOBELJOOCE-UHFFFAOYSA-N 0.000 claims abstract description 6
- 229910052791 calcium Inorganic materials 0.000 claims abstract description 6
- 239000011575 calcium Substances 0.000 claims abstract description 6
- 238000011282 treatment Methods 0.000 claims abstract description 6
- 238000005096 rolling process Methods 0.000 claims description 40
- 238000010438 heat treatment Methods 0.000 claims description 22
- 238000010583 slow cooling Methods 0.000 claims description 18
- XEEYBQQBJWHFJM-UHFFFAOYSA-N iron Substances [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims description 16
- 229910052719 titanium Inorganic materials 0.000 claims description 10
- 229910052748 manganese Inorganic materials 0.000 claims description 8
- 229910052757 nitrogen Inorganic materials 0.000 claims description 8
- 238000004321 preservation Methods 0.000 claims description 8
- 229910052717 sulfur Inorganic materials 0.000 claims description 8
- 229910052750 molybdenum Inorganic materials 0.000 claims description 7
- 229910052720 vanadium Inorganic materials 0.000 claims description 7
- 229910052698 phosphorus Inorganic materials 0.000 claims description 6
- 229910052742 iron Inorganic materials 0.000 claims description 5
- 238000010079 rubber tapping Methods 0.000 claims description 4
- 229910052760 oxygen Inorganic materials 0.000 claims description 3
- 229910001208 Crucible steel Inorganic materials 0.000 claims 1
- 238000001556 precipitation Methods 0.000 abstract description 16
- ATJFFYVFTNAWJD-UHFFFAOYSA-N Tin Chemical compound [Sn] ATJFFYVFTNAWJD-UHFFFAOYSA-N 0.000 abstract description 9
- 238000005266 casting Methods 0.000 abstract description 7
- 238000000265 homogenisation Methods 0.000 abstract description 3
- 239000007788 liquid Substances 0.000 abstract description 2
- 230000000052 comparative effect Effects 0.000 description 12
- 229910000859 α-Fe Inorganic materials 0.000 description 9
- 238000005204 segregation Methods 0.000 description 8
- 239000000126 substance Substances 0.000 description 8
- 229910001566 austenite Inorganic materials 0.000 description 7
- 238000005728 strengthening Methods 0.000 description 7
- 230000009466 transformation Effects 0.000 description 5
- 229910000734 martensite Inorganic materials 0.000 description 4
- 229910001562 pearlite Inorganic materials 0.000 description 4
- 238000001953 recrystallisation Methods 0.000 description 4
- 229910045601 alloy Inorganic materials 0.000 description 3
- 239000000956 alloy Substances 0.000 description 3
- 238000005452 bending Methods 0.000 description 3
- 229910001567 cementite Inorganic materials 0.000 description 3
- 230000000694 effects Effects 0.000 description 3
- KSOKAHYVTMZFBJ-UHFFFAOYSA-N iron;methane Chemical compound C.[Fe].[Fe].[Fe] KSOKAHYVTMZFBJ-UHFFFAOYSA-N 0.000 description 3
- 239000002244 precipitate Substances 0.000 description 3
- 230000001737 promoting effect Effects 0.000 description 3
- 230000009286 beneficial effect Effects 0.000 description 2
- 230000015572 biosynthetic process Effects 0.000 description 2
- 239000013078 crystal Substances 0.000 description 2
- 210000001787 dendrite Anatomy 0.000 description 2
- 239000011159 matrix material Substances 0.000 description 2
- 239000000203 mixture Substances 0.000 description 2
- 229910052758 niobium Inorganic materials 0.000 description 2
- 238000010899 nucleation Methods 0.000 description 2
- 230000006911 nucleation Effects 0.000 description 2
- 239000000047 product Substances 0.000 description 2
- 239000006104 solid solution Substances 0.000 description 2
- 229910020012 Nb—Ti Inorganic materials 0.000 description 1
- 229910011214 Ti—Mo Inorganic materials 0.000 description 1
- 230000002159 abnormal effect Effects 0.000 description 1
- 238000005275 alloying Methods 0.000 description 1
- 238000000137 annealing Methods 0.000 description 1
- 229910001563 bainite Inorganic materials 0.000 description 1
- 229910052796 boron Inorganic materials 0.000 description 1
- 229910052804 chromium Inorganic materials 0.000 description 1
- 239000002131 composite material Substances 0.000 description 1
- 239000000498 cooling water Substances 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 239000006185 dispersion Substances 0.000 description 1
- 238000004134 energy conservation Methods 0.000 description 1
- 230000002349 favourable effect Effects 0.000 description 1
- 239000012467 final product Substances 0.000 description 1
- 229910052739 hydrogen Inorganic materials 0.000 description 1
- 238000009776 industrial production Methods 0.000 description 1
- 230000016507 interphase Effects 0.000 description 1
- 239000002245 particle Substances 0.000 description 1
- 238000005191 phase separation Methods 0.000 description 1
- 238000007747 plating Methods 0.000 description 1
- 238000002360 preparation method Methods 0.000 description 1
- 238000003303 reheating Methods 0.000 description 1
- 238000005496 tempering Methods 0.000 description 1
- 239000013585 weight reducing agent Substances 0.000 description 1
Images
Classifications
-
- 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
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
- B22D11/00—Continuous casting of metals, i.e. casting in indefinite lengths
- B22D11/16—Controlling or regulating processes or operations
- B22D11/18—Controlling or regulating processes or operations for pouring
-
- 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
- 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
- C22C38/02—Ferrous alloys, e.g. steel alloys containing silicon
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/04—Ferrous alloys, e.g. steel alloys containing manganese
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/06—Ferrous alloys, e.g. steel alloys containing aluminium
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/12—Ferrous alloys, e.g. steel alloys containing tungsten, tantalum, molybdenum, vanadium, or niobium
-
- C—CHEMISTRY; METALLURGY
- 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
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P10/00—Technologies related to metal processing
- Y02P10/20—Recycling
Landscapes
- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Materials Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Physics & Mathematics (AREA)
- Thermal Sciences (AREA)
- Crystallography & Structural Chemistry (AREA)
- Heat Treatment Of Steel (AREA)
- Heat Treatment Of Sheet Steel (AREA)
Abstract
The invention relates to an ultra-high strength hot rolled steel strip with the thickness less than 4mm and a production method thereof, wherein the steel strip comprises the following components: 0.07-0.14% of C, 1.70-1.90% of Mn1.05-0.40% of Si, less than or equal to 0.015% of P, less than or equal to 0.005% of S, 0.010-0.060% of Als, less than or equal to 0.0040% of N, less than or equal to 0.0020% of O, 0.13-0.17% of Ti, 0.15-0.20% of Mo, 0.08-0.12% of V, and the balance of Fe and inevitable impurities, wherein the ratio of [ Ti ] -48[ N ]/14-96[ S ]/32)/([ C ] -12[ S ]/32) < 1.2. The method comprises the steps of desulfurization, converter smelting, LF refining, RH vacuum refining, calcium treatment, continuous casting, hot rolling, laminar cooling and curling. The casting blank homogenization, the liquid precipitation TiN control and the TiC precipitation phase regulation are carried out, the process is optimized, and the cost is reduced.
Description
Technical Field
The invention relates to an ultrahigh-strength hot-rolled steel strip with the thickness less than 4mm and a production method thereof, belonging to the technical field of steel strip rolling.
Background
In recent years, more and more attention is paid to resource conservation, energy conservation and emission reduction. The method is obvious in the automobile manufacturing industry, for example, increasingly strict emission standards are provided in the passenger vehicle industry, the development of new energy automobiles is greatly promoted, and the method is embodied in the aspects of light weight and weight reduction in the commercial vehicle industry. At present, 700 MPa-level tensile strength hot-rolled high-strength steel is generally applied to commercial vehicle frames, and achieves a remarkable light-weight effect, but the steel for the carriage mainly has a low strength level, and the light-weight level needs to be improved. Therefore, there is still a great need to develop high-strength hot rolled steel to promote the high-strength and light-weight process of commercial vehicles.
A high-strength thin steel sheet and a method for manufacturing the same are disclosed in the domestic patent publication No. CN 104254632B. The components by weight percentage are as follows: c: 0.08-0.20%, Mn: 0.1-3.0%, Si: 0.3% or less, Al: 0.10% or less, P: 0.10% or less, S: 0.030% or less, N: 0.010%, V: 0.20-0.80%, and one or two groups of Ti, Nb/Mo, B and Cr/Ni, and the rest is Fe and inevitable impurities. The steel with the above components is heated, rough rolled, finish rolled and annealed by plating to obtain a thin steel plate with yield strength of more than 1000MPa, the microstructure of the thin steel plate is more than 95% of ferrite, the grain size of precipitated phase is less than 10nm, and the number density is 1.0 multiplied by 105/um 3. VN microalloying is adopted in the method, proper strength is obtained through precipitation strengthening, but N easily forms N2 to cause bubbles under the skin of a casting blank, and the yield fluctuation of V in the finish rolling process is large, so the steel has certain limitation, and meanwhile, the annealing heat treatment can also increase the process cost.
The national patent, publication number CN 103194676B, discloses a 1000MPa super ferritic steel and a preparation method thereof, the components of which are calculated by weight percentage: c: 0.085-0.09%, Mn: 1.7-1.74%, Si: 0.21-0.23%, P: 0.053-0.0080%, S: 0.0050 to 0.0078%, N: 0.0041-0.0050%, Ti: 0.14 to 0.19%, Mo: 0.37-0.55%, and the balance of Fe and inevitable impurities. The components are smelted, cast and forged into a steel billet, the steel billet is heated at the temperature of 1250-. The invention is that the steel smelted in the laboratory is rolled after being forged into the billet, the sample size is smaller, and the uniformity of the steel smelted in the electric furnace in the laboratory is better, and when the industrial trial-manufacturing route of continuous casting, heating and rolling is adopted, the billet size is larger, the homogenization of the casting blank, the homogenization of the microstructure and the control difficulty of large-size liquated TiN are higher, so the invention has technical difficulty to be popularized to the industrial trial-manufacturing.
The national patent, publication No. CN 109023111B, discloses 1000 MPa-level hot-rolled automobile girder steel and a production method thereof, and the components thereof are calculated by weight percentage: c: 0.10-0.20%, Mn: 1.5-1.7%, Si is less than or equal to 0.10%, P is less than or equal to 0.015%, S is less than or equal to 0.005%, Nb: 0.045-0.055%, Ti: 0.08-0.10%, N is less than or equal to 40ppm, Als: 0.025-0.06%, H is less than or equal to 0.002%, and the balance is Fe and inevitable impurities. By adopting the production process of deep desulfurization pretreatment, converter smelting, LF refining, RH refining, continuous casting, slab heating, rough rolling, finish rolling and ultra-fast cooling, the finished steel with yield strength of more than or equal to 750MPa, tensile strength of more than or equal to 1000MPa, elongation of more than or equal to 10 percent, qualified 180-degree cold bending d-4 a and martensite proportion of more than or equal to 80 percent is obtained. According to the invention, Nb-Ti composite micro-alloying is adopted, and a rapid cooling process is combined to obtain the steel with most martensite of matrix structure, and tempering heat treatment is not carried out, so that the steel is expected to have low toughness, poor formability and limited application field.
In summary, most of the prior patents adopt a heat treatment process or form martensite to improve the strength and sacrifice the toughness so as to obtain 1000 MPa-grade ultrahigh-strength hot rolled steel, and have the defects of high production cost, insufficient comprehensive mechanical properties and difficulty in wide application through industrial production.
Disclosure of Invention
The invention aims to solve the technical problems that the production cost is higher and the comprehensive mechanical property is insufficient when the ultrahigh-strength hot rolled steel is produced by the existing process.
The technical scheme adopted by the invention for solving the technical problems is as follows: an ultra-high strength hot rolled steel strip with the thickness less than 4mm comprises the following components in percentage by weight: c: 0.07-0.14%, Mn: 1.70-1.90%, Si: 0.05-0.40%, P is less than or equal to 0.015%, S is less than or equal to 0.005%, Als: 0.010-0.060%, N is less than or equal to 0.0040%, O is less than or equal to 0.0020%, Ti: 0.13-0.17%, Mo 0.15-0.20%, V: 0.08 to 0.12% and satisfies 0.9 ≦ ([ Ti ] -48[ N ]/14 to 96[ S ]/32)/([ C ] -12[ S ]/32) ≦ 1.2, and the balance Fe and unavoidable impurities.
A production method of an ultrahigh-strength hot-rolled steel strip with the thickness less than 4mm comprises the following steps: the method comprises the steps of molten iron pre-desulfurization, converter smelting, LF refining, RH vacuum refining, calcium treatment, continuous casting, hot rolling, laminar cooling and coiling.
Wherein, the continuous casting billet in the method adopts low-temperature constant-speed casting, the temperature of the tundish is 1535-1545 ℃, the soft reduction is more than or equal to 5mm, the pulling speed is 0.9-1.2m/min, and the fluctuation of the pulling speed within 10s is not more than 0.05 m/min.
The continuous casting billet in the method directly enters a slab heating furnace through hot charging or enters the slab heating furnace through stacking and slow cooling.
Further, in the method, the tapping temperature of the steel billet in the slab heating furnace is 1230-; the total furnace time of furnace charging after slow cooling is 200-320min, and the stage heating time of the billet temperature being more than or equal to 1200 ℃ is more than or equal to 120 min.
Further, the width of the reheated steel billet in the method is adjusted by a fixed width press, and the side pressure of the fixed width is less than or equal to 150 mm.
The method comprises the following steps of rolling a steel billet in two stages, sending the steel billet into a roughing mill for roughing, adopting 5-pass or 6-pass rolling, wherein the first-pass deformation is more than or equal to 19 percent, the other-pass single-pass deformation is more than or equal to 20 percent, and the thickness of an intermediate billet obtained after roughing is 36-42 mm.
Further, in the method, the intermediate blank is sent into a hot coil box or a heat preservation cover for heat preservation, the intermediate blank is sent into a finishing mill for finish rolling, 6-pass or 7-pass rolling is adopted, and the final rolling temperature is 860-940 ℃.
Further, in the method, the steel plate after finish rolling is subjected to laminar cooling, the cooling rate of 30-60 ℃/s is adopted for concentrated cooling, the final cooling temperature is 620-670 ℃, then coiling is carried out, the coiling temperature of the tail part 10m of the steel coil is 650-700 ℃, and the coiling temperature of the rest positions is 580-640 ℃.
Further, the coiled steel coil is sent into a slow cooling pit for slow cooling in the method, and the slow cooling time is more than or equal to 36 hours.
The invention has the beneficial effects that:
1. the steel provided by the method does not need to be subjected to heat treatment, and has the characteristics of low production cost, good equipment adaptability and capability of being produced on a common hot continuous rolling line.
2. The microstructure of the steel provided by the method is ferrite plus a precipitated phase, the strength and toughness are considered, and the forming performance is more excellent compared with high-strength steel with a martensite structure.
3. The method provides the measures of dendritic crystal segregation and component segregation of the steel, microstructure uniformity, liquid precipitation TiN control and precipitated phase regulation and control, and provides a strength and toughness control scheme of the ultra-high-strength hot rolled steel with the grade of 1000 MPa.
4. The method promotes the development and popularization of new hot-rolled products, promotes the development of hot-rolled high-strength steel, and meets the requirement of the national automobile manufacturing development. Meanwhile, the yield of each ton of steel is estimated to be 1000 yuan, and the yield is estimated to be 100 ten thousand yuan according to the annual yield of 1000 tons.
Drawings
FIG. 1 is a schematic microstructure of example 1 of the present invention;
FIG. 2 is a schematic microstructure of example 2 of the present invention;
FIG. 3 is a schematic microstructure of example 3 of the present invention;
FIG. 4 is a schematic microstructure of example 4 of the present invention;
FIG. 5 is a schematic view of the present invention showing the liquating of TiN;
FIG. 6 is a schematic view of the morphology of TiC precipitates of the present invention;
FIG. 7 is a schematic view of the microstructure of comparative example 1 of the present invention.
FIG. 8 is a schematic view of the microstructure of comparative example 2 of the present invention;
FIG. 9 is a schematic view of the microstructure of comparative example 3 of the present invention;
FIG. 10 is a schematic view of the microstructure of comparative example 4 of the present invention.
Detailed Description
The present invention will be further described with reference to the following examples and accompanying drawings.
As shown in fig. 1 to 10, the ultra-high strength hot rolled steel strip with a thickness of less than 4mm according to the present invention comprises the following components by weight: c: 0.07-0.14%, Mn: 1.70-1.90%, Si: 0.05-0.40%, P is less than or equal to 0.015%, S is less than or equal to 0.005%, Als: 0.010-0.060%, N is less than or equal to 0.0040%, O is less than or equal to 0.0020%, Ti: 0.13-0.17%, Mo 0.15-0.20%, V: 0.08 to 0.12% and satisfies 0.9 ≦ ([ Ti ] -48[ N ]/14 to 96[ S ]/32)/([ C ] -12[ S ]/32) ≦ 1.2, and the balance Fe and unavoidable impurities. As will be understood by those skilled in the art, C is mainly responsible for interstitial solid solution strengthening and forms carbide with V, Ti, Mo, etc., thereby performing precipitation strengthening, and thus a certain C content must be maintained, but if the C content is too high, pearlite or grain boundary cementite is easily formed, the carbide precipitation phase is reduced, and the strength of the steel is reduced, so that the C content is controlled to 0.07 to 0.14%.
Mn and Si are solid solution strengthening elements, and too high Mn easily causes center segregation and dendrite segregation and improves plasticity, influences the uniformity of the structure and reduces the obdurability, so that the Mn content is controlled to be 1.70-1.90%. Si can also improve the transformation temperature and inhibit the formation of cementite, but the plasticity of the steel is easily reduced due to the excessively high Si content, so the Si content is controlled to be 0.05-0.40%.
V can play a role in precipitation strengthening and refining original austenite grains by promoting austenite recrystallization. The content of V is controlled to be 0.08-0.12%.
The main functions of Mo are to improve the hardenability of steel, to suppress pearlite transformation, and to promote fine dispersion of the second phase precipitate of V, Ti, thereby improving the toughness of steel. The content of Mo is controlled to be 0.15-0.20%.
Ti is the most main precipitation strengthening original in the test steel, but because the chemical property of Ti is more active, S, N element in steel is easy to form large-particle inclusions such as Ti4C2S2, liquated TiN and the like, the N, S element content in the steel must be controlled, the liquated TiN is easy to grow up due to overhigh Ti content, the N content is controlled to be less than or equal to 0.0040%, the S content is controlled to be less than or equal to 0.0050%, and the Ti content is controlled to be 0.13-0.17%. Meanwhile, in order to fully exert the precipitation strengthening effect of TiC, the elements meet the following ideal chemical proportion: 0.9-1.2 of ([ Ti ] -48[ N ]/14-96[ S ]/32)/([ C ] -12[ S ]/32).
A production method of an ultrahigh-strength hot-rolled steel strip with the thickness less than 4mm comprises the following steps: the method comprises the steps of molten iron pre-desulfurization, converter smelting, LF refining, RH vacuum refining, calcium treatment, continuous casting, hot rolling, laminar cooling and coiling. It can be understood by those skilled in the art that the billet with the thickness of 200- & ltwbr/& gtmm of the above chemical composition is preferably obtained through the flow of molten iron pre-desulfurization → converter smelting → LF refining → RH vacuum refining → calcium treatment → continuous casting. And simultaneously, limiting the chemical components of the steel strip, and preparing the steel strip by molten iron pre-desulfurization, converter smelting, LF refining, RH vacuum refining, calcium treatment, continuous casting, hot rolling, laminar cooling and coiling, wherein the yield strength is more than or equal to 800MPa, the tensile strength is 950-1050MPa, the elongation is more than 14%, the steel strip is qualified when the steel strip is subjected to a 180-degree cold bending test d which is 2a, the microstructure of the steel strip is more than 95% of ferrite structure, the grain size is 13.5-14.0 grade, the size of liquated TiN is less than 5 microns, and the size of a second-phase precipitate is less than 10 nanometers.
Wherein, the continuous casting billet in the method adopts low-temperature constant-speed casting, the temperature of the tundish is 1535-1545 ℃, the soft reduction is more than or equal to 5mm, the pulling speed is 0.9-1.2m/min, and the fluctuation of the pulling speed within 10s is not more than 0.05 m/min. As can be understood by those skilled in the art, in order to control the quality of the steel billet, the method actually prefers that the continuous casting steel billet is cast at a constant speed at a low temperature, wherein the temperature of a tundish is 1535 ℃ and 1545 ℃, the drawing speed is 0.9-1.2m/min under a light press, and the fluctuation of the drawing speed within 10s is not higher than 0.05 m/min.
The continuous casting billet in the method directly enters a slab heating furnace through hot charging or enters the slab heating furnace through stacking and slow cooling. As will be appreciated by those skilled in the art,
further, in the method, the tapping temperature of the steel billet in the slab heating furnace is 1230-; the total furnace time of furnace charging after slow cooling is 200-320min, and the stage heating time of the billet temperature being more than or equal to 1200 ℃ is more than or equal to 120 min. As can be understood by those skilled in the art, the main function of slab reheating is to make alloy elements solid-dissolve, if the slab heating temperature is lower, the alloy elements such as V, Ti, Mo and the like in the finished steel are not fully solid-dissolved, and the subsequent second phase precipitation is reduced, so that the strength is lower. Meanwhile, the higher slab heating temperature is easy to reduce the problems of dendrite segregation, component segregation and the like caused by the casting slab, so the tapping temperature is set at 1230-1270 ℃, and the stage heating time of the slab temperature being more than or equal to 1200 ℃ is required to be more than or equal to 120 min.
Further, the width of the reheated steel billet in the method is adjusted by a fixed width press, and the side pressure of the fixed width is less than or equal to 150 mm. As can be appreciated by those skilled in the art, in order to facilitate the subsequent hot rolling, the method preferably adjusts the width of the reheated slab by a constant width press, and the constant width side pressure is less than or equal to 150 mm.
The method comprises the following steps of rolling a steel billet in two stages, sending the steel billet into a roughing mill for roughing, adopting 5-pass or 6-pass rolling, wherein the first-pass deformation is more than or equal to 19 percent, the other-pass single-pass deformation is more than or equal to 20 percent, and the thickness of an intermediate billet obtained after roughing is 36-42 mm. As can be understood by those skilled in the art, the main effect of rough rolling is to refine grains through austenite dynamic recrystallization, and the single-pass deformation of the rough rolling must be larger than the critical deformation, otherwise, the central deformation of the steel plate is easy to be insufficient, so that the first-pass deformation of the rough rolling is controlled to be more than or equal to 19%, and the single-pass deformation of the rest passes is controlled to be more than or equal to 20%. Meanwhile, the adoption of the lower thickness of the intermediate blank is beneficial to improving the deformation amount of rough rolling, promoting the high-temperature precipitation of a recrystallization zone and refining austenite grains during finish rolling, thereby achieving the purpose of refining finished steel grains. Therefore, the present invention sets the thickness of the intermediate billet to 36 to 42 mm.
Further, in the method, the intermediate blank is sent into a hot coil box or a heat preservation cover for heat preservation, the intermediate blank is sent into a finishing mill for finish rolling, 6-pass or 7-pass rolling is adopted, and the final rolling temperature is 860-940 ℃. As will be understood by those skilled in the art, the primary function of finish rolling is to provide nucleation energy and nucleation sites for subsequent transformation by non-recrystallization deformation of austenite, wherein the finish rolling reduction and rolling temperature are key process parameters, the thickness of the intermediate billet is set to 36-42mm, the thickness of the finished product is 1.8-4.0mm, and the finish rolling reduction is 9 at the lowest, sufficient to fully refine austenite during finish rolling. Meanwhile, the steel plate is thin, the whole steel coil is long, the temperature of the tail part of the steel plate is obviously reduced, and a hot coil box or a heat preservation cover is adopted for heat preservation before finish rolling for reducing the temperature reduction of the tail part of the steel coil. In addition, in order to prevent the reduction of the strain-induced precipitation during the finish rolling when the rolling temperature is too low, thereby lowering the strength of the finished steel, the finish rolling temperature is controlled to a high level, i.e., to the range of 860 ℃ and 940 ℃.
Further, in the method, the steel plate after finish rolling is subjected to laminar cooling, the cooling rate of 30-60 ℃/s is adopted for concentrated cooling, the final cooling temperature is 620-670 ℃, then coiling is carried out, the coiling temperature of the tail part 10m of the steel coil is 650-700 ℃, and the coiling temperature of the rest positions is 580-640 ℃. As can be understood by those skilled in the art, phase transformation and interphase precipitation can occur during laminar cooling, and ferrite supersaturation precipitation can occur during subsequent coiling and slow cooling. In order to avoid forming coarse proeutectoid ferrite, pearlite, grain boundary cementite and other abnormal structures in the cooling process, rapid concentrated cooling is carried out by adopting a rapid cooling rate and a low final cooling temperature, so that the austenite structure is converted into a full ferrite structure. The cooling rate and the final cooling temperature are preferably controlled to 30-60 ℃/s and 620 ℃ and 670 ℃ respectively, and at the final cooling temperature, the phase separation is also favorably promoted. In addition, the coiling temperature is mainly set by considering that the nose point temperature of the supersaturated ferrite precipitation is positioned near 600 ℃, the coiling temperature is controlled in the range of 580-640 ℃, which is favorable for promoting the supersaturated ferrite precipitation, and meanwhile, the higher coiling temperature is adopted at the tail part of the steel coil so as to reduce the temperature loss in the steel coil in the coiling process.
Further, the coiled steel coil is sent into a slow cooling pit for slow cooling in the method, and the slow cooling time is more than or equal to 36 hours. As can be understood by those skilled in the art, the method preferably sends the coiled steel coil into a slow cooling pit for slow cooling, and the final product can be obtained after the slow cooling time is more than or equal to 36 hours.
Table 1 shows the compositions of examples and comparative examples, Table 2 shows hot rolling process parameters of examples and comparative examples, and Table 3 shows mechanical properties of steels of examples and comparative examples.
TABLE 1
TABLE 2
TABLE 3
In the method, the V-Ti-Mo component route is adopted in the embodiment 1 to the embodiment 4, the finished steel plate is obtained through hot continuous rolling and rapid cooling, and the mechanical property meets the requirements that the tensile strength is 950-1050MPa, the yield strength is more than 800MPa, the elongation is more than 14 percent, and the 180-degree cold bending test d is qualified as 2 a. The combination of the attached figures 5 and 6 shows that TiN can be controlled below 5 microns, and the precipitated phase of nano TiC is dispersed and distributed in the matrix.
The chemical components of the comparative example 1 have low Mn and Ti contents, the heating temperature of the plate blank is more than or equal to 1200 ℃, the time is short, the alloy elements are not fully dissolved, and the tensile strength of the finished steel is low. In comparative example 2 ([ Ti ] -48[ N ]/14-96[ S ]/32)/([ C ] -12[ S ]/32): 0.69, the stoichiometry is not satisfied, it is shown that C has a margin in addition to the formation of the MC precipitated phase, and since comparative example 2 has a low cooling rate and a high final cooling temperature, transformation of coarse pro-eutectoid ferrite and pearlite structures is easily promoted, resulting in a decrease in the strength of the finished steel. The chemical components of the comparative example 3 meet the requirements, but the cooling speed is too high, the final cooling temperature is lower, the second phase is inhibited from being separated out, the strength of the finished steel is reduced, and the microstructure of the finished steel is bainite. The content of N in chemical components is higher than that of the chemical components in comparative example 4, the probability of forming liquated TiN is increased, the temperature of the ladle is higher, the secondary cooling water adopts a weak cooling mode, dendritic crystal segregation and component segregation of a casting blank are easily caused, the laminar cooling rate is lower, the final cooling temperature is higher, the microstructure is further coarse, and the strength and the toughness of steel are reduced.
Claims (10)
1. An ultra-high strength hot rolled steel strip with the thickness less than 4mm is characterized by comprising the following components in percentage by weight: c: 0.07-0.14%, Mn: 1.70-1.90%, Si: 0.05-0.40%, P is less than or equal to 0.015%, S is less than or equal to 0.005%, Als: 0.010-0.060%, N is less than or equal to 0.0040%, O is less than or equal to 0.0020%, Ti: 0.13-0.17%, Mo 0.15-0.20%, V: 0.08 to 0.12% and satisfies 0.9 ≦ ([ Ti ] -48[ N ]/14 to 96[ S ]/32)/([ C ] -12[ S ]/32) ≦ 1.2, and the balance Fe and unavoidable impurities.
2. A production method of an ultrahigh-strength hot-rolled steel strip with the thickness less than 4mm is characterized by comprising the following steps: the method comprises the steps of molten iron pre-desulfurization, converter smelting, LF refining, RH vacuum refining, calcium treatment, continuous casting, hot rolling, laminar cooling and coiling.
3. A method of producing ultra high strength hot rolled steel strip having a thickness < 4mm as claimed in claim 2 wherein: the continuous casting billet is cast at a low temperature and a constant speed, the temperature of the tundish is 1535-1545 ℃, the soft reduction is more than or equal to 5mm, the pulling speed is 0.9-1.2m/min, and the fluctuation of the pulling speed within 10s is not more than 0.05 m/min.
4. A method of producing ultra high strength hot rolled steel strip having a thickness < 4mm as claimed in claim 2 wherein: the continuously cast steel billet is directly fed into a slab heating furnace through hot charging or is fed into the slab heating furnace after being stacked and slowly cooled.
5. A method of producing ultra high strength hot rolled steel strip having a thickness < 4mm as claimed in claim 4 wherein: the tapping temperature of the steel billet in the slab heating furnace is 1230-; the total furnace time of furnace charging after slow cooling is 200-320min, and the stage heating time of the billet temperature being more than or equal to 1200 ℃ is more than or equal to 120 min.
6. A method of producing ultra high strength hot rolled steel strip having a thickness < 4mm as claimed in claim 5 wherein: the width of the reheated billet is adjusted by a fixed-width press, and the side pressure of the fixed width is less than or equal to 150 mm.
7. A method of producing ultra high strength hot rolled steel strip having a thickness < 4mm as claimed in claim 2 wherein: the method comprises the following steps of rolling a steel billet in two stages, sending the steel billet into a rough rolling mill for rough rolling, adopting 5-pass or 6-pass rolling, wherein the first-pass deformation is more than or equal to 19 percent, the other-pass single-pass deformation is more than or equal to 20 percent, and the thickness of an intermediate billet obtained after rough rolling is 36-42 mm.
8. A method of producing ultra high strength hot rolled steel strip having a thickness < 4mm as claimed in claim 7 wherein: and (3) conveying the intermediate blank into a hot coil box or a heat preservation cover for heat preservation, conveying the intermediate blank into a finishing mill for finish rolling, and adopting 6-pass or 7-pass rolling at the finishing temperature of 860-940 ℃.
9. A method of producing ultra high strength hot rolled steel strip having a thickness < 4mm as claimed in claim 8 wherein: and carrying out laminar cooling on the finish-rolled steel plate, carrying out concentrated cooling at a cooling rate of 30-60 ℃/s, wherein the final cooling temperature is 620-670 ℃, then coiling is carried out, the coiling temperature of the tail part 10m of the steel coil is 650-700 ℃, and the coiling temperature of the rest positions is 580-640 ℃.
10. A method of producing ultra high strength hot rolled steel strip having a thickness < 4mm as claimed in claim 9 wherein: and feeding the coiled steel coil into a slow cooling pit for slow cooling, wherein the slow cooling time is more than or equal to 36 h.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202111274414.XA CN114000064B (en) | 2021-10-29 | 2021-10-29 | Ultrahigh-strength hot-rolled steel strip with thickness less than 4mm and production method thereof |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202111274414.XA CN114000064B (en) | 2021-10-29 | 2021-10-29 | Ultrahigh-strength hot-rolled steel strip with thickness less than 4mm and production method thereof |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN114000064A true CN114000064A (en) | 2022-02-01 |
| CN114000064B CN114000064B (en) | 2023-03-31 |
Family
ID=79925326
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202111274414.XA Active CN114000064B (en) | 2021-10-29 | 2021-10-29 | Ultrahigh-strength hot-rolled steel strip with thickness less than 4mm and production method thereof |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN114000064B (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114686753A (en) * | 2022-04-20 | 2022-07-01 | 张家港宏昌钢板有限公司 | Method for producing 40Mn hot-rolled steel, and use thereof |
| CN115710612A (en) * | 2022-09-13 | 2023-02-24 | 攀钢集团攀枝花钢铁研究院有限公司 | Production method of vanadium-titanium-containing steel |
Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN106756471A (en) * | 2016-11-11 | 2017-05-31 | 攀钢集团攀枝花钢铁研究院有限公司 | 345MPa grades of vanadium titanium microalloying anti-seismic structure hot continuous rolling steel band and preparation method thereof |
| CN107151763A (en) * | 2017-05-27 | 2017-09-12 | 武汉钢铁有限公司 | The high-strength cold-formed use hot rolled strip of Thin Specs and its production method |
| CN109182909A (en) * | 2018-10-12 | 2019-01-11 | 攀钢集团攀枝花钢铁研究院有限公司 | Automobile steering system medium carbon steel and its production method |
| CN109735775A (en) * | 2019-02-12 | 2019-05-10 | 唐山不锈钢有限责任公司 | A kind of 1000MPa grades of superhigh-strength hot strip rolling and its production method |
| CN113278872A (en) * | 2021-05-19 | 2021-08-20 | 攀钢集团研究院有限公司 | VN microalloying engineering machinery steel and manufacturing method thereof |
-
2021
- 2021-10-29 CN CN202111274414.XA patent/CN114000064B/en active Active
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN106756471A (en) * | 2016-11-11 | 2017-05-31 | 攀钢集团攀枝花钢铁研究院有限公司 | 345MPa grades of vanadium titanium microalloying anti-seismic structure hot continuous rolling steel band and preparation method thereof |
| CN107151763A (en) * | 2017-05-27 | 2017-09-12 | 武汉钢铁有限公司 | The high-strength cold-formed use hot rolled strip of Thin Specs and its production method |
| CN109182909A (en) * | 2018-10-12 | 2019-01-11 | 攀钢集团攀枝花钢铁研究院有限公司 | Automobile steering system medium carbon steel and its production method |
| CN109735775A (en) * | 2019-02-12 | 2019-05-10 | 唐山不锈钢有限责任公司 | A kind of 1000MPa grades of superhigh-strength hot strip rolling and its production method |
| CN113278872A (en) * | 2021-05-19 | 2021-08-20 | 攀钢集团研究院有限公司 | VN microalloying engineering machinery steel and manufacturing method thereof |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114686753A (en) * | 2022-04-20 | 2022-07-01 | 张家港宏昌钢板有限公司 | Method for producing 40Mn hot-rolled steel, and use thereof |
| CN115710612A (en) * | 2022-09-13 | 2023-02-24 | 攀钢集团攀枝花钢铁研究院有限公司 | Production method of vanadium-titanium-containing steel |
Also Published As
| Publication number | Publication date |
|---|---|
| CN114000064B (en) | 2023-03-31 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN102586688B (en) | A kind of dual phase sheet steel and manufacture method thereof | |
| CN107502819B (en) | A kind of 600MPa grades of 0.6mm or less thin gauge cold-rolled biphase steel and preparation method thereof | |
| CN111996467A (en) | 980 MPa-grade galvanized high-strength steel and preparation method thereof | |
| CN107012392B (en) | A kind of 600MPa grade high-strength low-alloy cold-strip steel and its production method | |
| CN111172466B (en) | Plasticity-enhanced cold-rolled dual-phase steel with tensile strength of 590MPa and production method thereof | |
| CN106636911B (en) | With the 900MPa grade hot rolled steel sheets and its manufacturing method of sheet billet Direct Rolling | |
| CN114000064B (en) | Ultrahigh-strength hot-rolled steel strip with thickness less than 4mm and production method thereof | |
| CN110592348A (en) | Ultra-low carbon cold rolled steel performance grading control method | |
| CN112779401B (en) | High-reaming hot-rolled pickled steel plate with yield strength of 550MPa | |
| CN112410671A (en) | Production method for producing steel for rim by adopting complex phase structure | |
| CN103361552A (en) | V-N microalloyed 460MPa thick plate and manufacturing method thereof | |
| CN114921726A (en) | Low-cost high-yield-ratio cold-rolled hot-galvanized ultrahigh-strength steel and production method thereof | |
| CN113957359A (en) | High-strength steel for automobile wheels and preparation method thereof | |
| CN109735768A (en) | A kind of 650MPa level low alloy high-strength steel and its production method | |
| CN113802054A (en) | Hot rolled steel plate with yield strength of 420MPa and manufacturing method thereof | |
| CN115572912B (en) | Economical 460 MPa-level steel plate cooling uniformity control method for engineering structure | |
| CN115491593B (en) | Hot rolled thin strip steel with tensile strength more than or equal to 1800MPa and produced by adopting TSR production line and method | |
| CN114000068B (en) | Low-nitrogen ultrahigh-strength hot-rolled steel strip with thickness of 4-10mm and production method thereof | |
| CN107829026B (en) | thin-specification 980 MPa-grade dual-phase steel and processing method thereof | |
| CN116103566A (en) | Steel with good low-temperature toughness for railway bogie and thick specification and manufacturing method thereof | |
| CN110938771A (en) | Hot-rolled steel plate for wheel with tensile strength of 630MPa and manufacturing method thereof | |
| CN112410676B (en) | Hot-rolled low-carbon steel and production method thereof | |
| CN115232938A (en) | Hot rolled steel strip for 700 MPa-level high-strength engineering machinery and production method thereof | |
| CN113403540A (en) | 500 MPa-level low-alloy high-strength cold-rolled steel plate and production method thereof | |
| CN105838997B (en) | Si Mn system 780MPa grade hot-rolled dual-phase steels and its production method |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| GR01 | Patent grant | ||
| GR01 | Patent grant | ||
| TR01 | Transfer of patent right | ||
| TR01 | Transfer of patent right |
Effective date of registration: 20231123 Address after: 617000 Taoyuan street, East District, Panzhihua, Sichuan Province, No. 90 Patentee after: PANGANG GROUP PANZHIHUA IRON & STEEL RESEARCH INSTITUTE Co.,Ltd. Patentee after: PANGANG GROUP PANZHIHUA STEEL & VANADIUM Co.,Ltd. Patentee after: XICHANG STEEL VANADIUM CO.,LTD., PANGANG Group Address before: 617000 Taoyuan street, East District, Panzhihua, Sichuan Province, No. 90 Patentee before: PANGANG GROUP PANZHIHUA IRON & STEEL RESEARCH INSTITUTE Co.,Ltd. |