CN117070853A - Economical 550 MPa-grade hot rolled steel plate and elongation stable control method thereof - Google Patents
Economical 550 MPa-grade hot rolled steel plate and elongation stable control method thereof Download PDFInfo
- Publication number
- CN117070853A CN117070853A CN202311050744.XA CN202311050744A CN117070853A CN 117070853 A CN117070853 A CN 117070853A CN 202311050744 A CN202311050744 A CN 202311050744A CN 117070853 A CN117070853 A CN 117070853A
- Authority
- CN
- China
- Prior art keywords
- steel plate
- percent
- rolling
- cooling
- equal
- 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.)
- Pending
Links
- 229910000831 Steel Inorganic materials 0.000 title claims abstract description 169
- 239000010959 steel Substances 0.000 title claims abstract description 169
- 238000000034 method Methods 0.000 title claims abstract description 61
- 238000001816 cooling Methods 0.000 claims abstract description 64
- 238000010438 heat treatment Methods 0.000 claims abstract description 44
- 230000008569 process Effects 0.000 claims abstract description 37
- 230000009467 reduction Effects 0.000 claims abstract description 33
- 238000004519 manufacturing process Methods 0.000 claims abstract description 15
- 239000000126 substance Substances 0.000 claims abstract description 10
- 239000012535 impurity Substances 0.000 claims abstract description 7
- 238000005096 rolling process Methods 0.000 claims description 82
- 238000009749 continuous casting Methods 0.000 claims description 37
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 27
- 238000010583 slow cooling Methods 0.000 claims description 24
- 238000003723 Smelting Methods 0.000 claims description 20
- 238000005266 casting Methods 0.000 claims description 20
- 238000005507 spraying Methods 0.000 claims description 14
- 238000012937 correction Methods 0.000 claims description 13
- XEEYBQQBJWHFJM-UHFFFAOYSA-N iron Substances [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims description 12
- 229910052799 carbon Inorganic materials 0.000 claims description 11
- 238000002791 soaking Methods 0.000 claims description 10
- 229910052758 niobium Inorganic materials 0.000 claims description 8
- 239000002994 raw material Substances 0.000 claims description 8
- 239000002893 slag Substances 0.000 claims description 8
- 229910052720 vanadium Inorganic materials 0.000 claims description 8
- 229910052698 phosphorus Inorganic materials 0.000 claims description 6
- 229910052717 sulfur Inorganic materials 0.000 claims description 6
- 239000000446 fuel Substances 0.000 claims description 5
- 229910052748 manganese Inorganic materials 0.000 claims description 5
- 238000001953 recrystallisation Methods 0.000 claims description 5
- 238000007670 refining Methods 0.000 claims description 5
- 238000003756 stirring Methods 0.000 claims description 5
- 229910052719 titanium Inorganic materials 0.000 claims description 5
- 238000009849 vacuum degassing Methods 0.000 claims description 5
- 230000001133 acceleration Effects 0.000 claims description 4
- 229910052782 aluminium Inorganic materials 0.000 claims description 4
- 229910052742 iron Inorganic materials 0.000 claims description 4
- 229910052757 nitrogen Inorganic materials 0.000 claims description 4
- 238000007711 solidification Methods 0.000 claims description 4
- 230000008023 solidification Effects 0.000 claims description 4
- 229910045601 alloy Inorganic materials 0.000 abstract description 16
- 239000000956 alloy Substances 0.000 abstract description 16
- 238000005496 tempering Methods 0.000 abstract description 5
- 238000004781 supercooling Methods 0.000 abstract description 3
- 230000001276 controlling effect Effects 0.000 description 21
- 239000010955 niobium Substances 0.000 description 13
- 239000011572 manganese Substances 0.000 description 10
- 238000005728 strengthening Methods 0.000 description 10
- 239000010936 titanium Substances 0.000 description 8
- 229910001566 austenite Inorganic materials 0.000 description 7
- 238000005204 segregation Methods 0.000 description 7
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 6
- 229910001563 bainite Inorganic materials 0.000 description 6
- 238000013461 design Methods 0.000 description 6
- 230000000694 effects Effects 0.000 description 6
- 229910000734 martensite Inorganic materials 0.000 description 6
- 239000011159 matrix material Substances 0.000 description 6
- 230000009286 beneficial effect Effects 0.000 description 5
- 229910000859 α-Fe Inorganic materials 0.000 description 5
- ATJFFYVFTNAWJD-UHFFFAOYSA-N Tin Chemical compound [Sn] ATJFFYVFTNAWJD-UHFFFAOYSA-N 0.000 description 4
- 230000015572 biosynthetic process Effects 0.000 description 4
- 238000011009 performance qualification Methods 0.000 description 4
- 238000001556 precipitation Methods 0.000 description 4
- 239000006104 solid solution Substances 0.000 description 4
- 230000006866 deterioration Effects 0.000 description 3
- 230000006872 improvement Effects 0.000 description 3
- 150000004767 nitrides Chemical class 0.000 description 3
- 239000002245 particle Substances 0.000 description 3
- 238000011160 research Methods 0.000 description 3
- 230000009466 transformation Effects 0.000 description 3
- 208000012868 Overgrowth Diseases 0.000 description 2
- 238000004220 aggregation Methods 0.000 description 2
- 230000002776 aggregation Effects 0.000 description 2
- 239000013078 crystal Substances 0.000 description 2
- 230000007547 defect Effects 0.000 description 2
- 229910052751 metal Inorganic materials 0.000 description 2
- 239000002184 metal Substances 0.000 description 2
- 239000000203 mixture Substances 0.000 description 2
- 229910001562 pearlite Inorganic materials 0.000 description 2
- 230000001105 regulatory effect Effects 0.000 description 2
- 239000007787 solid Substances 0.000 description 2
- 229910000851 Alloy steel Inorganic materials 0.000 description 1
- VYZAMTAEIAYCRO-UHFFFAOYSA-N Chromium Chemical compound [Cr] VYZAMTAEIAYCRO-UHFFFAOYSA-N 0.000 description 1
- 229910000617 Mangalloy Inorganic materials 0.000 description 1
- PWHULOQIROXLJO-UHFFFAOYSA-N Manganese Chemical compound [Mn] PWHULOQIROXLJO-UHFFFAOYSA-N 0.000 description 1
- ZOKXTWBITQBERF-UHFFFAOYSA-N Molybdenum Chemical compound [Mo] ZOKXTWBITQBERF-UHFFFAOYSA-N 0.000 description 1
- 229910000746 Structural steel Inorganic materials 0.000 description 1
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 description 1
- QFGIVKNKFPCKAW-UHFFFAOYSA-N [Mn].[C] Chemical compound [Mn].[C] QFGIVKNKFPCKAW-UHFFFAOYSA-N 0.000 description 1
- 238000005275 alloying Methods 0.000 description 1
- 238000004458 analytical method Methods 0.000 description 1
- 238000010923 batch production Methods 0.000 description 1
- 229910052804 chromium Inorganic materials 0.000 description 1
- 239000011651 chromium Substances 0.000 description 1
- 230000003749 cleanliness Effects 0.000 description 1
- 239000002131 composite material Substances 0.000 description 1
- 230000003111 delayed effect Effects 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 238000005098 hot rolling Methods 0.000 description 1
- 229910052739 hydrogen Inorganic materials 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 238000005272 metallurgy Methods 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 229910052750 molybdenum Inorganic materials 0.000 description 1
- 239000011733 molybdenum Substances 0.000 description 1
- GUCVJGMIXFAOAE-UHFFFAOYSA-N niobium atom Chemical compound [Nb] GUCVJGMIXFAOAE-UHFFFAOYSA-N 0.000 description 1
- 230000006911 nucleation Effects 0.000 description 1
- 238000010899 nucleation Methods 0.000 description 1
- TWNQGVIAIRXVLR-UHFFFAOYSA-N oxo(oxoalumanyloxy)alumane Chemical compound O=[Al]O[Al]=O TWNQGVIAIRXVLR-UHFFFAOYSA-N 0.000 description 1
- 229910052760 oxygen Inorganic materials 0.000 description 1
- 238000009628 steelmaking Methods 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
- 239000002344 surface layer Substances 0.000 description 1
- 230000000930 thermomechanical effect Effects 0.000 description 1
- LEONUFNNVUYDNQ-UHFFFAOYSA-N vanadium atom Chemical compound [V] LEONUFNNVUYDNQ-UHFFFAOYSA-N 0.000 description 1
- 238000003466 welding Methods 0.000 description 1
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
- B22D11/22—Controlling or regulating processes or operations for cooling cast stock or mould
- B22D11/225—Controlling or regulating processes or operations for cooling cast stock or mould for secondary cooling
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
- C21C5/00—Manufacture of carbon-steel, e.g. plain mild steel, medium carbon steel or cast steel or stainless steel
- C21C5/28—Manufacture of steel in the converter
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
- C21C7/00—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00
- C21C7/0075—Treating in a ladle furnace, e.g. up-/reheating of molten steel within the ladle
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
- C21C7/00—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00
- C21C7/10—Handling in a vacuum
-
- 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
- C22C38/001—Ferrous alloys, e.g. steel alloys containing N
-
- 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
-
- 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
Abstract
The invention relates to an economic 550MPa hot rolled steel plate and a stable control method for elongation thereof, wherein the steel plate comprises the chemical components of 0.13-0.17% of C, 0.20-0.40% of Si, 1.25-1.55% of Mn, less than or equal to 0.02% of P, less than or equal to 0.015% of S, 0.04-0.06% of Nb, 0.015-0.0250% of Ti, 0.015-0.035% of Al, 0.02-0.05% of V, 0.0004-0.0006% of B, 0.01-0.02% of N, 0.35-0.43% of Cev% of N, and the balance of Fe and impurities. By controlling each production process, the performance index requirements can be met without subsequent tempering heat treatment, and the problems that the model tracking is inaccurate and the cooling process window is narrowed after alloy reduction due to the fact that the head and tail temperatures of the economical steel plates are reduced rapidly and the length of the rolled steel plates is short, supercooling occurs at the head and the tail in the length direction of the steel plates, and the elongation of the steel plates is lower than the technical standard are solved.
Description
Technical Field
The invention relates to the technical field of hot-rolled steel plate production, in particular to a hot-rolled steel plate with thickness specification of 40-80 mm, economical grade and yield strength of 550MPa grade and a stable elongation control method thereof.
Background
The medium plate at 550MPa level is a main variety of the medium plate, and typically represents low-alloy Q550C/D/E steel, the steel is mainly based on carbon-manganese steel, and carbon and nitride forming elements such as microalloy element Nb, V, ti, cr are added into the steel, so that the toughness of the steel plate is improved through solid solution strengthening, precipitation strengthening and fine grain strengthening. According to statistics, the medium and heavy plates with the strength grade in the hot rolled steel plates produced annually in China account for 20-30% of the total yield. Therefore, development and research of manufacturing techniques of such low-cost steel sheets are significant. Along with the strict design indexes of engineering application fields such as engineering machinery, pipelines and the like, the requirements on indexes such as low-temperature toughness and the like of the steel plate are gradually improved on the premise of ensuring the service economy and the safety of the steel plate. For structural steel with special requirements on low-temperature toughness and 550MPa level, a low-carbon component design with carbon content below 0.10 percent is generally adopted, the manganese content is higher (1.6% -1.8%), and alloy elements such as niobium, vanadium, titanium, chromium, molybdenum and the like are added to ensure the performance, so that the production cost is relatively higher. If the medium and high carbon component design is adopted to replace the low carbon component design, the addition amount of alloy elements in steel is reduced, and meanwhile, the technological processes of steelmaking, rolling and cooling control are optimized, so that the alloy cost is obviously reduced.
TMCP (thermo-mechanical control process) is a technology generic term for performing air cooling or controlled cooling and accelerated cooling on the basis of controlled rolling by controlling a heating temperature, a rolling temperature and a rolling reduction in a hot rolling process. The TMCP process is considered to be an essential technique for producing low alloy steel sheets because it can produce high strength and high toughness steel without adding excessive alloying elements and requiring complicated subsequent heat treatment, and is a process that saves alloy and energy and is advantageous for environmental protection. As the market demands for TMCP steel continue to increase, the TMCP process itself is also continually evolving in application. Research from recent years has focused on controlling cooling, especially in terms of accelerated cooling. By accelerating the cooling rate after rolling, not only the growth of crystal grains can be suppressed, but also the ultra-fine ferrite structure or bainite structure, or even the martensite structure, required for high strength and high toughness can be obtained.
The economic steel plate with 550MPa grade steel plate with reduced alloy cost and reduced process is produced by adopting TMCP process, but the rolling and cooling control process window is narrowed along with the reduction of alloy content. For an economic TMCP steel plate with a thick specification (40-80 mm) and 550MPa level, the thickness of the TMCP steel plate is increased, the temperature of the head and the tail of the steel plate is reduced rapidly, and the cooling process window is narrowed after alloy reduction, so that the head and the tail of the steel plate in the length direction are supercooled, the elongation of the steel plate is lower than the technical standard, and the production and popularization of the steel plate of the level type are limited.
Therefore, how to solve the problem that the head-to-tail elongation is lower than the technical standard, simultaneously reduce the production cost and improve the performance qualification rate of the steel plate is a key problem to be solved in realizing batch production of the economic 550 MPa-level hot rolled steel plate steel with the thickness specification of 40-80 mm.
So far, few researches are conducted on a control method for ensuring that the head-to-tail elongation percentage meets the technical standard of an economic steel plate with the thickness of 40-80 mm and the yield strength of more than or equal to 550MPa at home and abroad. The journal paper "analysis of the reason of the low alloy high strength steel Q550D extension failure" ("Shanxi metallurgy" 2010.1) mainly enhances the toughness of the steel plate by means of improving the purity of molten steel, modifying the inclusions, optimizing the rolling and cooling control processes, adopting tempering heat treatment and the like, but greatly increases the production period and the cost due to the adoption of off-line tempering heat treatment.
The 550 MPa-level steel plate elongation control method disclosed in the above document solves the problem that the elongation of a part of steel plates with thickness specifications is unqualified, but is not suitable for producing the economic steel plate with the yield strength of 550MPa and the thickness specification of 40-80 mm by adopting TMCP to replace an off-line heat treatment process.
Disclosure of Invention
The invention aims to overcome the problems and the defects existing in the prior art and provide a hot rolled steel plate with thickness specification of 40-80 mm, economical and yield strength of 550MPa and a stable control method for the elongation thereof; by controlling each production process, the performance index requirements of the steel plate can be met without subsequent tempering heat treatment, and the problems that the model tracking is inaccurate and the cooling process window is narrowed after the alloy is reduced due to the fact that the head and tail temperature of the economical steel plate is reduced rapidly and the length of the rolled steel plate is short, the head and tail of the steel plate in the length direction is supercooled, the elongation of the steel plate is lower than the technical standard, and the one-time performance qualification rate of the steel plate is affected are solved.
In order to achieve the above purpose, the invention is realized by adopting the following technical scheme:
an economical 550 MPa-grade hot rolled steel plate comprises the following chemical components in percentage by weight: 0.13 to 0.17 percent of C, 0.20 to 0.40 percent of Si, 1.25 to 1.55 percent of Mn, less than or equal to 0.02 percent of P, less than or equal to 0.015 percent of S, 0.04 to 0.06 percent of Nb, 0.015 to 0.0250 percent of Ti, 0.015 to 0.035 percent of Al, 0.02 to 0.05 percent of V, 0.0004 to 0.0006 percent of B, 0.01 to 0.02 percent of N, 0.35 to 0.43 percent of Cev, and the balance of Fe and unavoidable impurities.
Further, the thickness of the finished steel plate is 40-80 mm.
Further, the yield strength of the transverse stretching of the finished steel plate is more than or equal to 550MPa, the tensile strength is 670-830 MPa, the elongation is more than or equal to 16%, and the transverse Charpy impact energy at minus 20 ℃ is more than or equal to 27J.
The economic stable control method for the elongation percentage of the 550 MPa-level hot rolled steel plate comprises the steps of molten steel smelting, continuous casting, casting blank heating, controlled rolling, cooling and stacking slow cooling in the steel plate production process; wherein the following processes are controlled:
1) Smelting molten steel: pretreating raw materials by KR molten iron, controlling the S content to be less than or equal to 0.02%, and feeding the raw materials into a converter after slag skimming; the double slag method is adopted to remove P in the converter smelting, the P content is controlled to be less than or equal to 0.030%, and the C content is controlled to be 0.15% -0.18% at the end point of the converter smelting; then LF refining and RH vacuum degassing are carried out, and RH vacuum is kept for more than 20 min;
2) Continuous casting: controlling the continuous casting superheat degree to be 15-20 ℃, the continuous casting blank drawing speed to be 1.2-1.7 m/min, controlling the electromagnetic stirring current intensity of a secondary cooling area in the continuous casting stage to be 250-300A, and controlling the secondary cooling specific water quantity to be 1.9-2.5L/kg; casting blanks after being off-line are stacked for more than 12 hours after being put into heavy reduction at the horizontal sector section, namely the solidification tail end, wherein the reduction of the continuous casting blanks is 15-20 mm;
3) Heating a casting blank: heating the casting blank, wherein the temperature of the preheating section is 980-1150 ℃, the heating temperatures of the soaking section and the heating section are 1220-1250 ℃, the total heating time of the soaking section and the heating section is 3-4 h, and the total furnace time is 5.5-6.5 h; controlling the air-fuel ratio to be 1:2.1-1:2.5;
4) And (3) rolling control: rolling in two stages; the first stage is recrystallization rolling, the initial rolling temperature of rough rolling is more than or equal to 1100 ℃, the final rolling temperature of rough rolling is 985-1020 ℃, the rough rolling is not more than six times, and the pass reduction system is as follows: the reduction rate of at least the first two passes is more than 15 percent; the second stage is non-crystallizing rolling, the finish rolling start temperature is 870-930 ℃, the finish rolling temperature is 800-840 ℃, the finish rolling is not more than six passes, and the pass reduction system is as follows: the reduction rate of at least two of the first four passes is more than 20 percent; pre-correction investment;
5) And (3) cooling: laminar cooling is adopted, the opening cooling temperature is 775-820 ℃, the final cooling temperature is 400-450 ℃, and the cooling speed is 13-18 ℃/s; full-automatic controlled cooling is adopted, steel plates are subjected to head-tail shielding investment, the opening correction value of an upper header is-600 to-800 mm, and the opening correction value of a lower header is-1000 to-1400 mm: the upper header and the lower header are respectively provided with 3-6 groups of water, and the opening water quantity is 200-230 m 3 And/h, the water ratio of the upper header to the lower header is 2-2.4; the roller speed of the steel plate conveying roller way is 2.0-3.0 m/s, and the acceleration is 0.005m/s 2 The method comprises the steps of carrying out a first treatment on the surface of the After the steel plate is cooled, the side spraying is opened, and the side spraying is pressedThe force is 1-3 MPa, and the side water spraying amount is 35-70 m 3 /h；
4) Stacking and slow cooling: and (3) carrying out stacking slow cooling on the cooled steel plates, wherein the stacking slow cooling temperature is 400-600 ℃, the number of stacking blocks is not less than 12, and the slow cooling time is more than 12 hours.
Further, the thickness of the continuous casting billet is less than or equal to 300mm, and the continuous casting billet is rolled on a medium plate reciprocating rolling mill.
Further, the thickness of the rolled intermediate billet is 2.0-4 times of the thickness of the finished steel plate; in the process of waiting for the temperature of the rolled intermediate blank, at least two passes of mill descaling water are sprayed, the descaling time of each pass is 1-1.5 min, and the descaling pressure is 20-25 MPa.
Compared with the prior art, the invention has the beneficial effects that:
1) The defects of casting blank center segregation, inclusion, H, O content exceeding and the like caused by higher Mn content are overcome by keeping RH vacuum degassing time, so that the toughness of the steel plate is improved; the average index of carbon segregation can be effectively reduced and the tendency of segregation and central crack deterioration of casting blank can be restrained by controlling the continuous casting superheat degree, the blank drawing speed, the electromagnetic stirring current intensity of a secondary cooling zone and the secondary cooling specific water quantity; the billets after being offline are stacked for more than 12 hours, so that the aggregation of residual H can be reduced, and the generation of microcracks in the billets can be inhibited;
2) By controlling the preheating temperature, carbide and nitride of Nb are ensured to be quickly and fully dissolved in the matrix and fully diffused; the higher heating temperature is adopted, the furnace time of the soaking section and the heating section is ensured, the air-fuel ratio is controlled, the temperature difference between the surface and the core of the continuous casting billet is shortened, the transverse and longitudinal metal flow uniformity of the surface of the steel plate is improved, and the temperature uniformity of the upper surface and the lower surface of the billet in the subsequent rolling process is ensured; the aim of controlling the total in-furnace time is to effectively inhibit the overgrowth of austenite grains and ensure the performance of the steel plate;
3) The steel plate has reasonable chemical component design and low alloy addition, and the alloy cost is greatly reduced by increasing the C content and reducing the Mn content and adding a small amount of microalloy elements Nb, ti and V; TMCP rolling is adopted, so that the initial rolling temperature is increased, the high-temperature deformation resistance in the rough rolling and finish rolling stages is reduced, the reduction of each pass is improved, and the comprehensive performance of the steel plate is ensured;
4) The rolling process is controlled in two stages, the pass reduction of rough rolling and finish rolling is controlled, the thickness of an intermediate blank is optimized, and a flexible and changeable intermediate blank cooling process is adopted, so that the surface and the core of the intermediate blank have temperature gradients, the surface to the core of the steel plate are uniformly organized, the growth of crystal grains is restrained, and the plastic toughness of the steel plate is improved; the aim of pre-correction investment is to ensure the uniformity of the temperature of each part of the head, the middle and the tail of the steel plate after the steel plate is put into water; the side spraying investment is beneficial to the control of the shape of the steel plate, further improves the uniformity of the performance of the steel plate and reduces the occurrence probability of the shape problems of the buckling head and the buckling tail; the final cooling temperature and cooling speed of the steel plate are controlled, the formation of bainite and martensite phases on the surface of the steel plate and the number of the bainite phases in a core structure can be inhibited, the influence of bainite or martensite phase transformation on the surface on the toughness of the steel plate is avoided, and the mechanical properties of the steel plate are ensured to meet the requirements;
5) The stacking slow cooling process is adopted, and the slow cooling temperature and time are strictly controlled, so that the contents of a core band structure and a surface layer martensitic structure or a metastable lath bainitic structure are effectively reduced, and the plasticity and toughness of the steel plate are ensured; the properties of the finished steel plate are as follows: the yield strength of transverse stretching is more than or equal to 550MPa, the tensile strength is between 670 and 830MPa, the elongation is more than or equal to 16 percent, and the transverse Charpy impact energy at minus 20 ℃ is more than or equal to 27J.
Detailed Description
The invention relates to an economic 550 MPa-grade hot rolled steel plate, which comprises the following chemical components in percentage by weight: 0.13 to 0.17 percent of C, 0.20 to 0.40 percent of Si, 1.25 to 1.55 percent of Mn, less than or equal to 0.02 percent of P, less than or equal to 0.015 percent of S, 0.04 to 0.06 percent of Nb, 0.015 to 0.0250 percent of Ti, 0.015 to 0.035 percent of Al, 0.02 to 0.05 percent of V, 0.0004 to 0.0006 percent of B, 0.01 to 0.02 percent of N, 0.35 to 0.43 percent of Cev, and the balance of Fe and unavoidable impurities.
Further, the thickness of the finished steel plate is 40-80 mm.
Further, the yield strength of the transverse stretching of the finished steel plate is more than or equal to 550MPa, the tensile strength is 670-830 MPa, the elongation is more than or equal to 16%, and the transverse Charpy impact energy at minus 20 ℃ is more than or equal to 27J.
The invention relates to an economic stable control method for the elongation percentage of a 550 MPa-grade hot rolled steel plate, wherein the steel plate production process comprises molten steel smelting, continuous casting, casting blank heating, controlled rolling, cooling and stacking slow cooling; wherein the following processes are controlled:
1) Smelting molten steel: pretreating raw materials by KR molten iron, controlling the S content to be less than or equal to 0.02%, and feeding the raw materials into a converter after slag skimming; the double slag method is adopted to remove P in the converter smelting, the P content is controlled to be less than or equal to 0.030%, and the C content is controlled to be 0.15% -0.18% at the end point of the converter smelting; then LF refining and RH vacuum degassing are carried out, and RH vacuum is kept for more than 20 min;
2) Continuous casting: controlling the continuous casting superheat degree to be 15-20 ℃, the continuous casting blank drawing speed to be 1.2-1.7 m/min, controlling the electromagnetic stirring current intensity of a secondary cooling area in the continuous casting stage to be 250-300A, and controlling the secondary cooling specific water quantity to be 1.9-2.5L/kg; casting blanks after being off-line are stacked for more than 12 hours after being put into heavy reduction at the horizontal sector section, namely the solidification tail end, wherein the reduction of the continuous casting blanks is 15-20 mm;
3) Heating a casting blank: heating the casting blank, wherein the temperature of the preheating section is 980-1150 ℃, the heating temperatures of the soaking section and the heating section are 1220-1250 ℃, the total heating time of the soaking section and the heating section is 3-4 h, and the total furnace time is 5.5-6.5 h; controlling the air-fuel ratio to be 1:2.1-1:2.5;
4) And (3) rolling control: rolling in two stages; the first stage is recrystallization rolling, the initial rolling temperature of rough rolling is more than or equal to 1100 ℃, the final rolling temperature of rough rolling is 985-1020 ℃, the rough rolling is not more than six times, and the pass reduction system is as follows: the reduction rate of at least the first two passes is more than 15 percent; the second stage is non-crystallizing rolling, the finish rolling start temperature is 870-930 ℃, the finish rolling temperature is 800-840 ℃, the finish rolling is not more than six passes, and the pass reduction system is as follows: the reduction rate of at least two of the first four passes is more than 20 percent; pre-correction investment;
5) And (3) cooling: laminar cooling is adopted, the opening cooling temperature is 775-820 ℃, the final cooling temperature is 400-450 ℃, and the cooling speed is 13-18 ℃/s; full-automatic controlled cooling is adopted, steel plates are subjected to head-tail shielding investment, the opening correction value of an upper header is-600 to-800 mm, and the opening correction value of a lower header is-1000 to-1400 mm: the upper header and the lower header are respectively provided with 3-6 groups of water, and the water is startedThe amount is 200-230 m 3 And/h, the water ratio of the upper header to the lower header is 2-2.4; the roller speed of the steel plate conveying roller way is 2.0-3.0 m/s, and the acceleration is 0.005m/s 2 The method comprises the steps of carrying out a first treatment on the surface of the The side spraying is started after the steel plate is cooled, the side spraying pressure is 1-3 MPa, and the side spraying water quantity is 35-70 m 3 /h；
4) Stacking and slow cooling: and (3) carrying out stacking slow cooling on the cooled steel plates, wherein the stacking slow cooling temperature is 400-600 ℃, the number of stacking blocks is not less than 12, and the slow cooling time is more than 12 hours.
Further, the thickness of the continuous casting billet is less than or equal to 300mm, and the continuous casting billet is rolled on a medium plate reciprocating rolling mill.
Further, the thickness of the rolled intermediate billet is 2.0-4 times of the thickness of the finished steel plate; in the process of waiting for the temperature of the rolled intermediate blank, at least two passes of mill descaling water are sprayed, the descaling time of each pass is 1-1.5 min, and the descaling pressure is 20-25 MPa.
The design principle of chemical components in the economic 550MPa hot rolled steel plate is as follows:
c: the steel is the most economical and basic strengthening element in the steel, and the strength of the steel can be obviously improved through solid solution strengthening and precipitation strengthening, but the improvement of the C content has negative effects on the plasticity, the toughness and the weldability of the steel. For this reason, the present invention sets the C content range to 0.13% to 0.17%.
Mn: the strength of the steel is improved by solid solution strengthening while compensating for the loss of strength of the steel sheet due to the decrease in the C content. In addition, the gamma-alpha transformation temperature can be reduced, ferrite grains are further refined, fine low-temperature transformation products are facilitated to be obtained, and the toughness of the products is improved. However, increasing the Mn content can aggravate the center segregation and the tissue deterioration of the continuous casting blank, is unfavorable for the improvement of the low-temperature toughness of the steel plate, and cannot ensure the uniformity of the cross-section tissue of the steel plate. Therefore, the Mn content range is set to 1.25% -1.55% in the present invention.
Si: has the functions of deoxidizing steel and improving the strength of the matrix. The improvement of Si content can purify ferrite and reduce pearlite content, which is beneficial to reducing the Bactger effect of the matrix material. However, since excessive Si reduces the toughness of the weld heat affected zone of the base material, the Si content is set to a range of 0.20% to 0.40% in the present invention.
N: the N element in the steel has no obvious effect except forming fine TiN grain refined austenite grains, so that the N element needs to be kept at a lower content level, and the N content is set to be 0.01-0.02 percent.
Al: it is usually used as a deoxidizer in steel and has the effect of refining the structure if AlN is formed. When the content of Al exceeds 0.035%, excessive aluminum oxide inclusions may decrease the cleanliness of the steel. However, when the Al content is too low, insufficient deoxidization is caused, and oxides are formed from easily oxidized elements such as Ti, so that the lower limit of the Al content is set to 0.015% in the present invention.
Nb: is one of common elements in modern microalloyed pipeline steel, has good fine grain strengthening and precipitation strengthening effects, and can delay austenite recrystallization; however, excessive Nb increases the production cost and difficulty in controlling the continuous casting process. According to the invention, the Nb content range is 0.04% -0.06%, and a reasonable TMCP process is matched, so that a uniform composite phase mainly comprising acicular ferrite or pearlite structure can be obtained, and the steel plate has good toughness.
V is a forming element with strong carbide and strong hardenability, can improve the low-temperature toughness of steel, and can improve the hardenability of steel, thereby improving the strength and the structural uniformity of steel, and simultaneously improving the hot brittleness of steel, and the V content range is selected to be 0.02-0.05%.
B-the element that enhances hardenability, B has an advantageous effect on hardenability because the nucleation process of ferrite is delayed, but the thermodynamic properties of the austenitic or ferritic matrix are not affected. Meanwhile, the solid solution B promotes the formation of a fine bainitic structure after controlled rolling and cooling, the fine bainitic structure contains more stable dislocation, deformation dislocation generated in austenite is inherited during the formation, and meanwhile, the steel plate toughness with the yield strength reaching 500-900 MPa can be obviously higher than that of common low-alloy high-strength steel by utilizing precipitation strengthening of Nb, ti, V and the like. The content range of B selected by the invention is 0.0004% -0.0006%.
Ti: is a strong solid N element, and exists in the form of TiN in the continuous casting billet. The fine TiN particles can effectively inhibit the growth of austenite grains when the continuous casting billet is reheated, and are beneficial to improving the solid solubility of Nb in austenite and improving the impact toughness of a welding heat affected zone. However, when the Ti addition exceeds a certain value, tiN particles coarsen, thereby improving the stress concentration level of the particle interface and the matrix. Therefore, the Ti content is selected to be 0.015-0.025%.
P, S: is an unavoidable impurity element in steel, and theoretically, the lower the concentration is, the better. But cannot be infinitely low due to smelting costs and process considerations. Therefore, the upper limit of the P, S content is set to 0.02% and 0.015%, respectively.
The thickness of the economical 550 MPa-grade hot rolled steel plate is 40-80 mm, and continuous casting blanks with the thickness below 300mm are used for production on a medium plate reciprocating mill. The production process comprises molten steel smelting, continuous casting, casting blank heating, controlled rolling, cooling and stacking slow cooling. In order to improve the condition that the elongation of the finished steel plate does not reach the standard, the following process is controlled:
1) Smelting molten steel: smelting according to the set chemical components, namely, 0.13 to 0.17 percent of C, 0.20 to 0.40 percent of Si, 1.25 to 1.55 percent of Mn, less than or equal to 0.02 percent of P, less than or equal to 0.015 percent of S, 0.04 to 0.06 percent of Nb, 0.015 to 0.0250 percent of Ti, 0.015 to 0.035 percent of Al, 0.02 to 0.05 percent of V, 0.0004 to 0.0006 percent of B, 0.01 to 0.02 percent of N, 0.35 to 0.43 percent of Cev, and the balance of Fe and unavoidable impurities. Raw materials are pretreated by KR molten iron, the S content is controlled to be lower than 0.02 percent, and the raw materials enter a converter after slag skimming; the double slag method is adopted to remove P in the converter smelting, the P content is controlled to be less than or equal to 0.030%, and the C content is controlled to be 0.15% -0.18% at the end point of the converter smelting; then LF refining and RH vacuum degassing are carried out, and RH vacuum is kept for more than 20 min.
2) Continuous casting: controlling the continuous casting superheat degree to be 15-20 ℃, the continuous casting blank drawing speed to be 1.2-1.7 m/min, controlling the electromagnetic stirring current intensity of a secondary cooling area in the continuous casting stage to be 250-300A, and controlling the secondary cooling specific water quantity to be 1.9-2.5L/kg; reducing the average index of carbon segregation by the above measures to suppress segregation; and the secondary cooling strength is limited, so that the trend of the deterioration of the central crack of the casting blank is restrained. The horizontal sector section, namely the solidification end, is put into heavy reduction, the continuous casting billet reduction is 15-20 mm, and the central loose grade and segregation of the casting billet are reduced; and stacking the cast blanks after the offline for more than 12 hours so as to reduce the aggregation of residual H and inhibit the generation of microcracks in the steel blanks.
3) Heating a casting blank: feeding a casting blank (with the thickness of below 300 mm) into a step heating furnace for heating, wherein the temperature interval of a preheating section is 980-1150 ℃, so that carbide and nitride of Nb are quickly and fully dissolved in a matrix and fully diffused; the heating temperature of the soaking section and the heating section is 1220-1250 ℃, the total heating time of the soaking section and the heating section is 3-4 hours, and the total furnace time is 5.5-6.5 hours. The opening degrees of the upper burner and the lower burner of the heating furnace are regulated, and the air-fuel ratio is controlled to be 1:2.1-1:2.5. The method adopts higher heating temperature and ensures the time of a soaking section and a heating section in a furnace, so as to shorten the temperature difference between the surface and the core of the continuous casting billet and improve the transverse and longitudinal metal flow uniformity of the surface of the steel plate. The total in-furnace time is controlled to effectively inhibit the overgrowth of austenite grains and ensure the performance of the steel plate.
4) And (3) rolling control: rolling in two stages; the first stage is recrystallization rolling (rough rolling), the initial rolling temperature of rough rolling is more than or equal to 1100 ℃, the final rolling temperature interval of rough rolling is 985-1020 ℃, the rough rolling is not more than six times, and the rolling reduction of the first two times is preferably more than 15%.
The thickness of the rolled intermediate billet is 2.0-4 times of the thickness of the finished steel plate; in the process of waiting for the temperature of the rolled intermediate billet, the descaling water of a two-pass rolling mill is preferably sprayed, the descaling time of each pass is 1-1.5 min, and the descaling pressure is 20-25 MPa.
The second stage is non-crystallizing rolling (finish rolling), the finish rolling initial temperature interval is 870-930 ℃, the finish rolling final temperature interval is 800-840 ℃, the finish rolling is not more than six passes, and the pass reduction system is that the reduction rate of the first four passes with two passes is more than 20%.
Grain structures at different stages are thinned through two-stage rolling, and the structures from the surface to the core of the steel plate are uniform through an intermediate billet cooling mode, so that the low-temperature toughness of the steel plate is improved. The purpose of the pre-correction investment is to prevent the steel plate head from tilting upwards in the rolling process, and water is stored on the surface of the steel plate in the subsequent cooling control process, so that the performance uniformity is affected.
5) And (3) cooling: collectingLaminar cooling is adopted, the opening cooling temperature range is 775-820 ℃, the final cooling temperature range is 400-450 ℃, and the cooling speed is 13-18 ℃/s. Full-automatic controlled cooling is adopted, steel plates are subjected to head-tail shielding investment, the opening correction value of an upper header is-600 to-800 mm, and the opening correction value of a lower header is-1000 to-1400 mm: the header is opened with 3-6 groups of water, and the opened water quantity is 200-230 m 3 And/h, the water ratio of the upper header to the lower header is 2-2.4; the roller speed of the steel plate conveying roller way is 2.0-3 m/s, and the acceleration is 0.005m/s 2 . The side spraying is started after the steel plate is cooled, the side spraying pressure is 1-3 MPa, and the side spraying water quantity is 35-70 m 3 And/h. The cooling speed and the reddening temperature are controlled in the cooling process, and the head and the tail of the steel plate are shielded during the cooling control, so that the bainite and martensite phase formation of different parts of the head, the middle and the tail of the steel plate and the number of the bainite phase in the core structure are effectively regulated and controlled, and the toughness of the steel plate is ensured. The side spraying investment is beneficial to controlling the shape of the steel plate, improving the uniformity of the performance of the steel plate and reducing the occurrence probability of shape problems such as buckling heads, buckling tails and the like.
6) Stacking and slow cooling: and (3) carrying out stacking slow cooling on the cooled steel plates, wherein the stacking slow cooling temperature is 400-600 ℃, the number of stacking blocks is not less than 12, and the slow cooling time is more than 12 hours. The low-temperature stacking is adopted, so that the contents of a strip-shaped structure, a martensitic structure or a metastable lath-shaped bainitic structure are reduced, and the plasticity and toughness of the steel plate are ensured.
The invention combines the chemical components and the production process, and solves the problems that the elongation of the steel plate is lower than the technical standard and the one-time performance qualification rate of the steel plate is affected because the head and tail temperature of the economic 550 MPa-level hot rolled steel plate is reduced rapidly and the cooling process window is narrowed after alloy reduction, so that supercooling occurs at the head and the tail of the steel plate in the length direction.
The following examples are given by way of illustration of detailed embodiments and specific procedures based on the technical scheme of the present invention, but the scope of the present invention is not limited to the following examples.
[ example ]
Table 1 shows the chemical composition of each example steel, table 2 shows the smelting process parameters of each example steel, and table 3 shows the heating process parameters of each example cast slab; table 4 shows rolling process parameters of the steels of each example; table 5 shows the reduction of each pass of each example steel at different rolling stages; table 6 shows the cooling control process parameters of the steel plates of each example; table 7 shows the stacking slow cooling process parameters and the properties of the finished steel plates of each example.
Table 1 chemical composition (wt.%)
| Examples | C | Si | Mn | N | Al | Nb | Ti | V | B | Cev |
| 1 | 0.16 | 0.35 | 1.52 | 0.016 | 0.026 | 0.041 | 0.016 | 0.038 | 0.0004 | 0.41 |
| 2 | 0.17 | 0.29 | 1.30 | 0.019 | 0.018 | 0.058 | 0.019 | 0.043 | 0.0006 | 0.39 |
| 3 | 0.15 | 0.38 | 1.45 | 0.020 | 0.029 | 0.049 | 0.025 | 0.025 | 0.0004 | 0.39 |
| 4 | 0.13 | 0.21 | 1.55 | 0.012 | 0.033 | 0.058 | 0.022 | 0.032 | 0.0005 | 0.39 |
| 5 | 0.14 | 0.29 | 1.52 | 0.018 | 0.028 | 0.043 | 0.018 | 0.041 | 0.0004 | 0.39 |
| 6 | 0.16 | 0.32 | 1.49 | 0.019 | 0.023 | 0.053 | 0.017 | 0.029 | 0.0006 | 0.41 |
Note that: the impurity element P in the steel is less than or equal to 0.02 percent, and S is less than or equal to 0.015 percent.
Table 2 parameters of the smelting process for steels
TABLE 3 heating process parameters of casting blanks
Table 4 parameters of the rolling process of steel
Table 5 reduction of steel in each pass at different rolling stages
Table 6 controlled cooling process parameters for steels
Table 7 stacking slow cooling process parameters of steel and properties of finished steel plate
Therefore, after the economic 550 MPa-level hot rolled steel plate elongation stable control method is adopted, the performance index requirements of the steel plate can be met without subsequent tempering heat treatment, and the problems that the economic steel plate is lower than the technical standard and the primary performance qualification rate of the steel plate is affected due to the fact that the head and tail temperature is reduced rapidly and the cooling process window is narrowed after alloy reduction, supercooling occurs at the head and the tail in the length direction of the steel plate are solved.
The foregoing is only a preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art, who is within the scope of the present invention, should make equivalent substitutions or modifications according to the technical scheme of the present invention and the inventive concept thereof, and should be covered by the scope of the present invention.
Claims (6)
1. An economical 550 MPa-grade hot rolled steel plate is characterized by comprising the following chemical components in percentage by weight: 0.13 to 0.17 percent of C, 0.20 to 0.40 percent of Si, 1.25 to 1.55 percent of Mn, less than or equal to 0.02 percent of P, less than or equal to 0.015 percent of S, 0.04 to 0.06 percent of Nb, 0.015 to 0.0250 percent of Ti, 0.015 to 0.035 percent of Al, 0.02 to 0.05 percent of V, 0.0004 to 0.0006 percent of B, 0.01 to 0.02 percent of N, 0.35 to 0.43 percent of Cev, and the balance of Fe and unavoidable impurities.
2. An economical 550 MPa-grade hot-rolled steel sheet according to claim 1, characterized in that the thickness of the finished steel sheet is 40-80 mm.
3. The economical 550 MPa-grade hot-rolled steel plate according to claim 1, wherein the yield strength of the transverse stretching of the finished steel plate is more than or equal to 550MPa, the tensile strength is 670-830 MPa, the elongation is more than or equal to 16%, and the transverse Charpy impact energy at-20 ℃ is more than or equal to 27J.
4. The stable elongation control method for an economical 550MPa grade hot rolled steel plate according to any one of claims 1 to 3, wherein the steel plate production process comprises molten steel smelting, continuous casting, casting blank heating, controlled rolling, cooling and stacking slow cooling; wherein the following processes are controlled:
1) Smelting molten steel: pretreating raw materials by KR molten iron, controlling the S content to be less than or equal to 0.02%, and feeding the raw materials into a converter after slag skimming; the double slag method is adopted to remove P in the converter smelting, the P content is controlled to be less than or equal to 0.030%, and the C content is controlled to be 0.15% -0.18% at the end point of the converter smelting; then LF refining and RH vacuum degassing are carried out, and RH vacuum is kept for more than 20 min;
2) Continuous casting: controlling the continuous casting superheat degree to be 15-20 ℃, the continuous casting blank drawing speed to be 1.2-1.7 m/min, controlling the electromagnetic stirring current intensity of a secondary cooling area in the continuous casting stage to be 250-300A, and controlling the secondary cooling specific water quantity to be 1.9-2.5L/kg; casting blanks after being off-line are stacked for more than 12 hours after being put into heavy reduction at the horizontal sector section, namely the solidification tail end, wherein the reduction of the continuous casting blanks is 15-20 mm;
3) Heating a casting blank: heating the casting blank, wherein the temperature of the preheating section is 980-1150 ℃, the heating temperatures of the soaking section and the heating section are 1220-1250 ℃, the total heating time of the soaking section and the heating section is 3-4 h, and the total furnace time is 5.5-6.5 h; controlling the air-fuel ratio to be 1:2.1-1:2.5;
4) And (3) rolling control: rolling in two stages; the first stage is recrystallization rolling, the initial rolling temperature of rough rolling is more than or equal to 1100 ℃, the final rolling temperature of rough rolling is 985-1020 ℃, the rough rolling is not more than six times, and the pass reduction system is as follows: the reduction rate of at least the first two passes is more than 15 percent; the second stage is non-crystallizing rolling, the finish rolling start temperature is 870-930 ℃, the finish rolling temperature is 800-840 ℃, the finish rolling is not more than six passes, and the pass reduction system is as follows: the reduction rate of at least two of the first four passes is more than 20 percent; pre-correction investment;
5) And (3) cooling: laminar cooling is adopted, the opening cooling temperature is 775-820 ℃, the final cooling temperature is 400-450 ℃, and the cooling speed is 13-18 ℃/s; full-automatic controlled cooling is adopted, steel plates are subjected to head-tail shielding investment, the opening correction value of an upper header is-600 to-800 mm, and the opening correction value of a lower header is-1000 to-1400 mm: the upper header and the lower header are respectively provided with 3-6 groups of water, and the opening water quantity is 200-230 m 3 And/h, the water ratio of the upper header to the lower header is 2-2.4; the roller speed of the steel plate conveying roller way is 2.0-3.0 m/s, and the acceleration is 0.005m/s 2 The method comprises the steps of carrying out a first treatment on the surface of the The side spraying is started after the steel plate is cooled, the side spraying pressure is 1-3 MPa, and the side spraying water quantity is 35-70 m 3 /h；
4) Stacking and slow cooling: and (3) carrying out stacking slow cooling on the cooled steel plates, wherein the stacking slow cooling temperature is 400-600 ℃, the number of stacking blocks is not less than 12, and the slow cooling time is more than 12 hours.
5. The stable control method for the elongation percentage of the economic 550MPa grade hot rolled steel plate according to claim 4, wherein the thickness of the continuous casting billet is less than or equal to 300mm, and the rolling is carried out on a medium plate reciprocating rolling mill.
6. The stable control method for elongation of an economical 550MPa grade hot rolled steel plate according to claim 4, wherein the thickness of the rolled intermediate billet is 2.0-4 times of the thickness of the finished steel plate; in the process of waiting for the temperature of the rolled intermediate blank, at least two passes of mill descaling water are sprayed, the descaling time of each pass is 1-1.5 min, and the descaling pressure is 20-25 MPa.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202311050744.XA CN117070853A (en) | 2023-08-21 | 2023-08-21 | Economical 550 MPa-grade hot rolled steel plate and elongation stable control method thereof |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202311050744.XA CN117070853A (en) | 2023-08-21 | 2023-08-21 | Economical 550 MPa-grade hot rolled steel plate and elongation stable control method thereof |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN117070853A true CN117070853A (en) | 2023-11-17 |
Family
ID=88707546
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202311050744.XA Pending CN117070853A (en) | 2023-08-21 | 2023-08-21 | Economical 550 MPa-grade hot rolled steel plate and elongation stable control method thereof |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN117070853A (en) |
-
2023
- 2023-08-21 CN CN202311050744.XA patent/CN117070853A/en active Pending
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN109536846B (en) | High-toughness hot-rolled steel plate with yield strength of 700MPa and manufacturing method thereof | |
| CN112981254B (en) | Wide high-strength high-toughness thick-wall X80M pipeline steel plate and manufacturing method thereof | |
| CN109097699B (en) | 900 MPa-grade hot-rolled automobile girder steel and manufacturing method thereof | |
| CN110629114A (en) | Low-cost high-strength high-toughness bridge steel and preparation method thereof | |
| CN111455269A (en) | Yield strength 960MPa grade very high strength marine steel plate and manufacturing method thereof | |
| CN110846577A (en) | 690 MPa-grade high-strength low-yield-ratio medium-thickness manganese steel and manufacturing method thereof | |
| CN112813344B (en) | High-strength high-toughness easy-to-weld structural steel plate with yield strength of 620MPa and preparation method thereof | |
| CN113430458B (en) | Ultrahigh-strength steel plate with yield strength of more than 1040MPa and manufacturing method thereof | |
| CN112981257A (en) | Economical thick-wall high-strength high-toughness X70M hot-rolled steel plate and manufacturing method thereof | |
| JP2661845B2 (en) | Manufacturing method of oxide-containing refractory section steel by controlled rolling | |
| CN112779401B (en) | High-reaming hot-rolled pickled steel plate with yield strength of 550MPa | |
| CN110157987B (en) | NQT-process-based large-thickness wear-resistant steel plate with good-40-DEG C low-temperature toughness and preparation method thereof | |
| CN113957359A (en) | High-strength steel for automobile wheels and preparation method thereof | |
| CN115572912B (en) | Economical 460 MPa-level steel plate cooling uniformity control method for engineering structure | |
| CN113802054A (en) | Hot rolled steel plate with yield strength of 420MPa and manufacturing method thereof | |
| CN114134387B (en) | 1300 MPa-tensile-strength thick-specification ultrahigh-strength steel plate and manufacturing method thereof | |
| CN115558851A (en) | Hot rolled steel plate for 370 MPa-level engineering structure and manufacturing method thereof | |
| CN113604736B (en) | High-strength medium plate with yield strength of 800MPa and preparation method thereof | |
| CN115572901A (en) | 630 MPa-grade high-hardening-tempering-stability low-carbon low-alloy steel plate and manufacturing method thereof | |
| CN111321340A (en) | Hot rolled steel plate with yield strength of 450MPa and manufacturing method thereof | |
| CN111910128B (en) | Steel plate for Q690-grade coal mine hydraulic support and production method thereof | |
| CN113755745B (en) | High-reaming hot-rolled pickled steel plate with tensile strength of 650MPa | |
| CN113802060A (en) | Low-cost steel plate for engineering structure and manufacturing method thereof | |
| CN117070853A (en) | Economical 550 MPa-grade hot rolled steel plate and elongation stable control method thereof | |
| CN115652211B (en) | Economical 420 MPa-level steel plate cooling uniformity control method for engineering structure |
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 |