CN107460413B - A kind of preparation method and application of 550MPa grades of Ultra-fine Grained high-strength weathering steel - Google Patents

A kind of preparation method and application of 550MPa grades of Ultra-fine Grained high-strength weathering steel Download PDF

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CN107460413B
CN107460413B CN201710703326.4A CN201710703326A CN107460413B CN 107460413 B CN107460413 B CN 107460413B CN 201710703326 A CN201710703326 A CN 201710703326A CN 107460413 B CN107460413 B CN 107460413B
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preparation
roughing
intermediate base
finish rolling
temperature
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CN107460413A (en
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武会宾
许立雄
秦哲
谢国海
刘宏志
朱经涛
王学伦
徐由标
安守勇
陈金伟
孙庆强
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University of Science and Technology Beijing USTB
Rizhao Steel Holding Group Co Ltd
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    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
    • C22C38/42—Ferrous alloys, e.g. steel alloys containing chromium with nickel with copper
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
    • C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
    • C21D8/0221—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the working steps
    • C21D8/0226—Hot rolling
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
    • C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
    • C21D8/0247—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the heat treatment
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • 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
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
    • C22C38/46—Ferrous alloys, e.g. steel alloys containing chromium with nickel with vanadium
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
    • C22C38/48—Ferrous alloys, e.g. steel alloys containing chromium with nickel with niobium or tantalum
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
    • C22C38/50—Ferrous alloys, e.g. steel alloys containing chromium with nickel with titanium or zirconium
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
    • C22C38/58—Ferrous alloys, e.g. steel alloys containing chromium with nickel with more than 1.5% by weight of manganese

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Mechanical Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Heat Treatment Of Sheet Steel (AREA)

Abstract

The present invention relates to a kind of preparation method and applications of 550MPa grades of Ultra-fine Grained high-strength weathering steel, the preparation method includes that continuous casting billet is directly entered M rack roughing mills under high pulling rate, (50%~60%) roughing is continuously depressed greatly by M passage, austenite grain significantly refines, after roughing, intermediate base quickly heats up to finish rolling entrance required temperature by induction heater, it is formed simultaneously reverse temperature field, then in turn through finish rolling group, section cooling, coiling machine, ultimately form that surface and core be relatively thick, thinner tissue signature at 1/4 thickness.Finish rolling and roughing are full endless rolling in production process.The present invention can get the Ultra-fine Grained high-strength weathering hot rolled strip that weatherability is equivalent to corten-A, realize the effect of " with Bao Daihou " and " with hot Dai Leng ", while making Vehicle mass reduction, improve Automobile Plate service life, production efficiency is improved, reduces production cost, while reducing energy consumption, discharge is reduced, realizes resource-conserving, environmentally friendly production.Belong to metallurgical technology field.

Description

A kind of preparation method and application of 550MPa grades of Ultra-fine Grained high-strength weathering steel
Technical field
The invention belongs to metallurgical technology fields.More particularly to a kind of preparation method of 550MPa grades of Ultra-fine Grained high-strength weathering steel And application.
Background technique
Weathering steel is adding a kind of low-alloy steel, major alloy made of a certain amount of alloying element in ordinary steel Ingredient is the elements such as Cu, P, Cr, Ni.Tough, modeling with high-quality steel prolong, form, welding, abrasion, high temperature, the spies such as antifatigue Property；Weatherability is 2~8 times of straight carbon steel, and coating is 1.5~10 times of straight carbon steel.Meanwhile it has antirust, keeps component anti- The features such as corrosion lengthens the life, consumption reduction is thinned, and saving of labor is energy saving.Compared to other lightweighting materials such as aluminium alloy, plastics, although high-strength steel Have many advantages, such as that at low cost, intensity is high, impact resistance is good, but its atmospheric corrosion resistance is relatively poor.In recent years, with China The fast development of national economy, the demand to the railway high-strength weathering steel of passenger and freight is increasing, in order to improve transport Efficiency mitigates carriage weight, saves transportation cost and extends compartment service life, it is desirable that the intensity of manufacture compartment weathering steel Rank and corrosion resisting property are continuously improved.Therefore, considering cost, processing method, recoverable etc., develop it is high-strength, The comprehensive performances such as ultra-thin, weather-proof are trends of the times in the high-strength steel of one.
High-strength weathering steel refers to Rel (yield strength) >=400MPa weathering steel, and this kind of steel is in special container and goods It is had broad application prospects in the manufacture of vehicle railway carriage.Since high-strength weathering steel is demanding corrosion proof while requiring height Intensity rank and preferable forming property and welding performance, therefore metallurgical technology process and equipment controlled level are required very The superhigh intensity weather-resistant steel plate of height, especially yield strength 550MPa, current only very few country can produce.Japanese, Germany, South Korea, Sweden etc. have produced the high-strength weathering steel of yield strength 400MPa or more using traditional process, are used for railcar With the production of boxcar.In contrast, China starts to walk in light weight material in automobile, especially high-strength weathering steel research and development with application Later, such as currently on the market using more box semitrailer carriage steel based on Q235 and Q345, not only intensity is low, weather-proof Performance is also poor.But, with the continuous intensification that domestic some iron and steel enterprises recognize automobile high-strength weathering steel, started in recent years Set about the exploitation and popularization of high-strength weathering Automobile Plate, the research and development of the weather-proof sheet billet of yield strength 550MPa grade high-strength become respectively Big steel mill and associated vehicle manufacturer focus of attention.
Currently, the industrial production of 550MPa grades of high-strength hot-strips of yield strength mostly uses the rolling of sheet billet list base or half nothing Head rolling mill practice, traditional mode of production process are as follows: → acid is batched in continuous casting → slab reheating → roughing → finish rolling → section cooling → Wash → cold rolling → annealing.The rolling bottom formula furnace or induction heater pair of 200-280m long are used as this rolling mill practice is previous in roughing Continuous casting billet is heated, and carries out cocurrent using rolling bottom formula.
Traditional rolling mill practice has production line length increase, equipment complicated composition, Operation and Maintenance is at high cost, energy consumption is high etc. Disadvantage.And since production line is too long (400m or more), essence is pricked inlet temperature and is unable to accurately control, and leads to the final structure property of product It is unstable.In addition, under the hot rolling surface quality and product specification of this single base rolling of tradition or semi-endless rolled production are not achieved It swims user to require, the hot rolled plate after pickling is generally required could supply by subsequent cold rolling, annealing process, so that production process is numerous Miscellaneous, production efficiency reduces, the production cost increases.
Summary of the invention
To solve the above problems, the present invention provides a kind of preparation method of 550MPa grades of Ultra-fine Grained high-strength weathering steel, tool Have the advantages that shorten process flow, fining austenite grains and the mechanical property for improving product.In addition, this method can be raw in ESP It is applied in producing line.
The present invention is achieved by the following technical solutions:
A kind of preparation method of 550MPa grades of Ultra-fine Grained high-strength weathering steel, the preparation method includes continuous casting step, roughing Step, finish rolling step, section cooling step and batch step；
The preparation method is that initial feed is successively passed through to continuous casting step, roughing step, finish rolling step, section cooling step It is rapid and after batching step, obtain final finished sheet billet；
The roughing step includes: that the continuous casting billet that the continuous casting step obtains is directly over M rack under high pulling rate is thick Milling train group carries out the big pressure of M passage, obtains intermediate base；
The roughing step and finish rolling step are full endless rolling.
Further, the high pulling rate is 3-7m/min.
Further, the M is positive integer, and M is not less than 3.
Further, the drafts of the big pressure of single pass of the big pressure of M passage is 50%-60%.
Further, the continuous casting billet that the continuous casting step obtains directly carries out roughing to it, without thick in traditional handicraft To the reheating link of slab before rolling, process flow is shortened, obtains higher single machine yield while reducing energy consumption.
Further, drafts big at high temperature in the roughing step refines original austenite grain significantly, Organization foundation is provided for final uniform tiny ferritic structure.
Further, the preparation method further includes intermediate base processing step；
The intermediate base processing step is after the roughing step；
The intermediate base processing step includes: that the intermediate base for obtaining the roughing step is placed in induction heater and quickly adds Heat is to temperature T1, the intermediate base that obtains that treated.
Further, the intermediate base processing step further include: the intermediate base for obtaining the roughing step successively passes through Rocking shears pushes away useless roller-way, after rotating hub is cut, then carries out induction heating.
Further, the temperature T1For the entry temperature at finishing of treated the intermediate base.
Further, the temperature T1It is 1100-1200 DEG C.
Further, the intermediate base processing step accurately controls intermediate base essence and pricks inlet temperature T1, meet and prick temperature eventually Degree requires；Meanwhile intermediate base surface temperature is high after induction heating, core temperature is low, and this reverse temperature field is slab thickness side Temperature basis is provided to special tissue signature's (surface and core are thicker, thinner at 1/4 thickness).
Further, the thickness of strand is 80-100mm.
Further, pulling rate is 3-7m/min in the continuous casting step.
It further, is 4-6.5t/min into the molten steel flow of casting machine in the continuous casting step.
Further, the finish rolling step includes: that treated that intermediate base carries out N to described using N rack mm finishing mill unit Passage pressure, obtains sheet billet.
Further, the N is positive integer, and N is not less than 5.
Further, the thickness specification of the sheet billet be 1.2-1.4mm, width specifications 1500mm.
Further, finishing temperature is 800-850 DEG C in the finish rolling step.
Further, the drafts of the single pass pressure of the N passage pressure is 30%-40%, can make austenite Crystal grain further refines, in addition, the lower certifiable austenite of finishing temperature is not being rolled in crystal region, increases dislocation density, increases Big deformation energy storage, improves the forming core rate of deformation induced ferrite and deformation-induced precipitation in subsequent cooling procedure.
Further, the section cooling step includes: the sheet billet for obtaining the finish rolling step, by equipped with a high position The laminar cooling system of water tank, takes the intensive type of cooling of leading portion, and the sheet billet is cooled to coiling temperature T2, cooled down Sheet billet.
Further, the coiling temperature T2It is 620-660 DEG C.
Further, in the section cooling step, cooling velocity is 50% or more.
Further, the section cooling step uses the intensive type of cooling of leading portion, and cooling velocity is 50% or more；This Kind of leading portion is intensive and the faster type of cooling, can make build up, and then improve the mechanical property of the final finished sheet billet.
Further, the step of batching includes: that the cooling sheet billet for obtaining the section cooling step carries out bundling Coiling process afterwards, coiling temperature T when batching2, it is air-cooled to room temperature after batching, obtains the final finished sheet billet.
Further, the bundling process carries out bundling using high-speed flying shear.
Further, the coiling process is batched using coiling machine.
Further, the preparation method further includes dephosphorization step, and the dephosphorization step is placed in front of the finish rolling step.
Further, after the dephosphorization step includes: the processing obtained using high pressure dephosphorization case to intermediate base processing step Intermediate base carry out dephosphorization.
A kind of application of the preparation method of 550MPa grades of Ultra-fine Grained high-strength weathering steel on ESP production line.
Further, the ESP production line overall length is 180-210m.
Further, the ESP production line overall length is 190m.
Further, each portion of ESP production line is directly connected to by strip.
Further, the production process of the ESP production line does not have threading and throws steel.
Further, the ESP production line continuous casting step is 6-10min to the time used in step is batched.
Further, the ESP production line continuous casting step is 7min to the time used in step is batched.
Further, the ESP production line can low cost, low energy consumption, it is compact, efficiently produce the high property of dimensional accuracy The excellent hot rolled thin strip coil of strip of energy.
A kind of application of the preparation method of 550MPa grades of Ultra-fine Grained high-strength weathering steels on ESP production line, is started Property use the big Reduction Technology of roughing and intermediate base induction heating technique, produce grain size number up to 13.0~13.5 grades Ultra-fine Grained high-strength weathering steel.
Further, the chemical composition of the initial feed include: carbon, silicon, aluminium, manganese, copper, titanium, niobium, nickel, chromium, phosphorus, sulphur, Nitrogen and iron；
The mass fraction of each chemical composition of initial feed are as follows: 0.02-0.06% carbon, 0.1-0.4% silicon, 1.0- 1.7% manganese, 0.01-0.05% aluminium, 0.1-0.4% copper, titanium 0.04-0.08%, niobium 0.02-0.05%, nickel 0.1-0.3%, chromium 0.3-0.7%, phosphorus≤0.015%, sulphur≤0.003%, nitrogen≤0.004%, surplus are iron.
Further, the thickness specification of the final finished sheet billet be 1.2-1.4mm, width specifications 1500mm, group Be woven to single-phase ferrite, mean grain size reaches 13.0-13.5 grade, and shows surface and core crystal grain is thicker, 1/4 it is thick at crystal grain Thinner tissue characteristic.At room temperature, precipitate mainly includes TiC, NbC and a small amount of (Ti, Nb) N, having a size of 500~200nm Between.In atmospheric environment, the weather-proof steel surface forms the double-deck corrosion products film, and internal layer is mainly the oxide of Cr, Ni, outside Layer is mainly the oxide and CuS of Fe.
The mass fraction of carbon (C) selects 0.02-0.06% in the initial feed, it is therefore an objective to continuous casting process be made to avoid peritectoid Reaction, prevents continuous casting billet solidification processing shrinkage big, and crackle even bleed-out is formed in subsequent roughing.Meanwhile excessively high C content The plasticity of steel can also declined, seriously affects the cold formability energy and weldability of steel.
The mass fraction of silicon (Si) selects 0.1-0.4% in the initial feed, is used as ferrite former, plays The effect of solution strengthening, in addition, the design of low silicon is conducive to improve weldability, cold formability and the antifatigue toughness of steel.
The mass fraction of manganese (Mn) selects 1.0-1.7% in the initial feed, on the one hand, manganese can pass through solution strengthening The intensity of steel when acting on guaranteeing low-carbon design；On the other hand, manganese can expand the area γ, reduce γ → α phase transition temperature, promote former material Material obtains low-temperature transformation tissue in quasi-polygonal ferrite or acicular ferrite structure etc., to improve matrix strength.But mistake High Mn content will affect the cold stamping and welding performance of steel, while rolling load being caused to increase.
The mass fraction of titanium (Ti) and niobium (Nb) selects 0.04-0.08% and 0.02- respectively in the initial feed 0.05%, micro titanium (Ti), niobium (Nb) is added mainly using the precipitation strength of carbonitride particle, to guarantee the strong of steel Degree.
In thin slab continuous casting and rolling process, excessively high Ti content be easy to cause slab side occur in the operation of rolling to split and make Unstable mechanical property is obtained, and excessively high Nb content be easy to cause mixed crystal.Due to the content of C, N in steel lower, excessively high Ti, Nb Content can not play enough invigoration effects, will increase the cost of steel instead.It can in addition, micro Ti, Nb element is added in steel The recrystallization temperature for improving steel enables steel to obtain the deformation of storage large deformation while can completing rolling at a higher temperature Austenite structure, and then tiny phase-change organization is obtained, the intensity of steel is improved by refined crystalline strengthening.
Chromium (Cr) in the initial feed, nickel (Ni), copper (Cu) mass fraction select 0.3-0.7%, 0.1- respectively 0.3%, 0.1-0.4%, chromium (Cr) and nickel (Ni) are primarily used to form fine and close internal layer corrosion products film, generate passivation to matrix Effect, copper (Cu) plug the hole in dimple shape rusty scale mainly with the formal distribution of CuS in outer layer corrosion products film, prevent The infiltration of etchant gas inner layer.Passivation and outer layer to matrix form corrosion products film and prevent etchant gas inner layer Both infiltrations act synergistically to reduce the corrosion rate of matrix, improve the weatherability of steel.
The mass fraction selection≤0.015% of phosphorus (P) in the initial feed, phosphorus (P) easily forms serious segregated zone, just The addition of phosphorus (P) can greatly improve the rank of banded structure in beginning raw material.
The mass fraction selection≤0.003% of sulphur (S) in the initial feed, since initial feed selects high Mn at setting up separately Meter, S form MnS field trash easily in steel, segregation phenomena occur.
The mass fraction selection≤0.004% of nitrogen (N) in the initial feed, nitrogen (N) easily generate slightly with Ti in high-temperature region Big liquation TiN, makes the Ti in steel lose precipitating reinforcing effect.
Therefore, it should try to control P, S in weathering steel, N content is in lower range.
The finished sheet base of obtained cooling after the section cooling is by bundling and batches, and slowly cools to after batching Room temperature.The mode for cooperating slow cooling after high temperature coiling, can be such that the nano-sized carbonitride of Ti, Nb is sufficiently precipitated, pass through strong analysis Invigoration effect further increases the mechanical property of steel out.
In atmospheric environment, the surface of the weathering steel forms the double-deck corrosion products film；The internal layer of the weathering steel is main For the oxide of Cr, Ni, the two forms fine and close corrosion products film, produces passivation to matrix, improve the anti-corrosion of matrix Performance；The outer layer of the weathering steel is mainly the oxide and CuS of Fe, wherein hole of the CuS integrated distribution in dimple shape rusty scale In, outer layer corrosion products film is plugged, the infiltration of atmosphere inner layer is prevented, to reduce the corrosion rate of matrix.Therefore, This anti-corrosion mechanism of bilayer that weathering steel has, so that the average corrosion rate in atmospheric environment of the weather-proof steel grade is less than 0.08g/(m2·h)。
Application of the preparation method on the ESP production line, the mechanics for the final finished sheet billet that the present invention obtains Performance are as follows: yield strength >=550MPa, tensile strength >=680MPa, elongation > 10.0%, yield tensile ratio < 0.94,180 ° of clod wash Performance is qualified.Weatherability is equivalent to corten-A.
The corten-A is to examine the one kind for stepping on steel, is the representative steel grade of U.S.'s Cu-P Series Steel, belongs to low-alloy high-strength Structural steel resisting atmosphere corrosion, the country are called weathering steel.
The ESP production line is the sheet billet endless rolling of new generation of Italian Giovanni Arvedi company invention Production line, the major techniques such as casting rate with higher, stable casting phase technology controlling and process, extensive automatic technology are special Point.
The reverse temperature field refers to that slab has surface and core temperature higher, the lower feature of temperature at 1/4 thickness.
A kind of preparation method of 550MPa grades of Ultra-fine Grained high-strength weathering steels of the invention has following advantageous effects:
(1) preparation method of the invention can improve the power of final finished sheet billet by build up and precipitation strength Learn performance.
(2) application of the preparation method of a kind of 550MPa grades of Ultra-fine Grained high-strength weathering steels of the invention on ESP production line, The big Reduction Technology of roughing and intermediate base induction heating technique are used in a creative way, produce grain size number up to 13.0~13.5 Ultra-fine Grained high-strength weathering steel.
(3) weathering steel that preparation method of the invention obtains has surface and core crystal grain thicker, and crystal grain is thinner at 1/4 thickness Tissue signature so that sheet billet has good cold forming capability, good atmospheric corrosion resistance improves weathering steel Service life.
(4) preparation method of compact, efficient endless rolling of the invention, can either meet thin gauge high-strength weathering automobile The production technology demand of Strip realizes the effect of " with Bao Daihou ", makes Vehicle mass reduction, to make effective load of automobile Quality increases, fuel consumption reduces and conevying efficiency improves；Again weathering steel can be improved under the premise of shortening production procedure Surface quality, reduce weathering steel thickness specification, realize " with hot Dai Leng " technical effect, improve weathering steel production effect Rate reduces weathering steel production cost, while reducing production energy consumption, reduces discharge, reaches resource-effective, environmentally friendly production Effect.
(5) method of the invention directly carries out roughing to it by the continuous casting billet that continuous casting step obtains, without traditional work Process flow is shortened to the reheating link of slab before roughing in skill, higher single machine is obtained while reducing energy consumption and is produced Amount.
(6) drafts big under method roughing step high temperature of the invention refines original austenite grain significantly, Organization foundation is provided for final uniform tiny ferritic structure.
(7) in method of the invention, intermediate base processing step accurately controls intermediate base essence and pricks inlet temperature, meets and pricks eventually Temperature requirement；Meanwhile intermediate base surface temperature is high after induction heating, core temperature is low, and this reverse temperature field is slab thickness The special tissue signature in direction (surface and core are thicker, thinner at 1/4 thickness) provides temperature basis.
(8) in method of the invention finish rolling step single pass rolling reduction be 30%-40%, can make austenite grain into Step refining increases dislocation density in addition, the lower certifiable austenite of finishing temperature is rolled in Unhydrated cement, increases deformation Energy storage improves the forming core rate of deformation induced ferrite and deformation-induced precipitation in subsequent cooling procedure.
(9) in method of the invention laminar flow cooling step use the intensive type of cooling of leading portion, and cooling velocity be 50% with On；This leading portion is intensive and the faster type of cooling, can make build up, and then improve the mechanical property of final products.
(10) preparation method of the invention is applied on ESP production line, have low cost, low energy consumption, it is compact, efficiently give birth to The characteristics of output dimensional accuracy high-performance excellent hot rolled thin strip coil of strip.
Detailed description of the invention
Fig. 1 is the schematic diagram of the application of preparation method of the invention on ESP production line.
Fig. 2 is the SEM pattern of the ferrite crystal grain in the embodiment of the present invention 1 at 1/4 thickness of weather-resistant steel plate.
Fig. 3 is the precipitate SEM pattern of nanoscale even dispersion distribution in the embodiment of the present invention 1.
Fig. 4 is the section SEM pattern for the corrosion products film that slab is formed in atmospheric environment in the embodiment of the present invention 1.
Description of symbols: the straight circular-arc type continuous casting machine of 1- tundish, 2-, 3- roughing mill, 4- rocking shears, 5- push away useless roller-way, 6- Rotating hub cuts, 7- induction heater, 8- high pressure dephosphorization case, 9- finishing mill, 10- laminar cooling system, 11- high-speed flying shear, the underground 12- Coiling machine.
Specific embodiment
In order to make the objectives, technical solutions, and advantages of the present invention clearer, with reference to the accompanying drawings and embodiments, right The present invention is explained in further detail.It should be appreciated that specific embodiment described herein is used only for explaining the present invention, and It is not used in the restriction present invention.
On the contrary, the present invention covers any substitution done on the essence and scope of the present invention being defined by the claims, repairs Change, equivalent method and scheme.Further, in order to make the public have a better understanding the present invention, below to of the invention thin It is detailed to describe some specific detail sections in section description.Part without these details for a person skilled in the art The present invention can also be understood completely in description.
Embodiment 1
The present embodiment provides a kind of preparation methods of 550MPa grades of Ultra-fine Grained high-strength weathering steel, as Figure 1-Figure 4.Its work Skill process is as follows:
Middle Baogang's water is prepared first: initial feed being melted successively to pass through BOF converter refining, LF furnace essence after obtaining molten iron Refining, the refining of RH refining furnace, obtain middle Baogang's water.
Then middle Baogang's water is put into ESP production line as shown in Figure 1.
Pass through continuous casting step → roughing step → centre base processing step → finish rolling step → section cooling in ESP production line Step → batch step obtains finished sheet base.
The continuous casting billet that middle Baogang's water is formed by straight circular-arc type continuous casting machine 2 with a thickness of 80mm.
The continuous casting billet is directly entered 3 rack roughing mills 3 under the high pulling rate of 3-7m/min and carries out roughing；
The drafts of the big pressure of single pass of single roughing mill is 50%-60% in the roughing step.The roughing enters Mouth temperature is 1163 DEG C.
The intermediate base processing step include: the intermediate base successively by rocking shears 4, push away useless roller-way 5, after rotating hub cuts 6, Temperature T is quickly heated up into induction heater 71, the intermediate base that obtains that treated；
The temperature T1Entry temperature at finishing as the intermediate base.
The temperature T1It is 1160 DEG C.
The finish rolling step includes: intermediate base temperature after the treatment when being 1160 DEG C using 5 rack mm finishing mill units 9 5 passage pressures are carried out, finished sheet base is obtained.
The thickness specification of the sheet billet is 1.4mm, width specifications 1500mm.
The finishing temperature of the finish rolling step is 825 DEG C.
The drafts of the single pass pressure of the single finishing mill of the finish rolling step is 30%-40%.
The section cooling step includes: the finished sheet base for obtaining the finish rolling step, by being furnished with high water tank Laminar cooling system, take the intensive type of cooling of leading portion, the finished sheet base cooled down, coiling temperature is cooled to T2, obtain cooling finished sheet base.
The temperature T2It is 620 DEG C.
In the section cooling step, cooling velocity is 50% or more.
The step of batching includes: to batch after the finished sheet base that the section cooling step obtains is carried out bundling, is rolled up Take temperature T2, it is slowly cooled to room temperature after batching.
The bundling process carries out bundling using high-speed flying shear 11.
The coiling process is batched using downcoiler 12.
The preparation method further includes dephosphorization step, and the dephosphorization step is placed in the intermediate base processing step and the essence It rolls between step.
The dephosphorization step includes: using the intermediate base processing steps of 8 pairs of the high pressure dephosphorization case intermediate base that obtains that treated Carry out dephosphorization.
Relevant technological parameter is as shown in following table 1-1 in the chemical composition and preparation method of the initial feed.
Relevant technological parameter in the chemical composition and preparation method of table 1-1 initial feed
In the chemical composition and preparation method of preparation method according to the present invention and the present embodiment selection initial feed Application of the relevant technological parameter on ESP production line, the 550MPa grade Ultra-fine Grained high-strength weathering steel being prepared is (hereinafter referred to as Weathering steel) product specification, mean grain size and mechanical property as shown in following table 1-2.
Product specification, mean grain size and the mechanical property of 550MPa grades of Ultra-fine Grained high-strength weathering steels of table 1-2
The present embodiment is analyzed as follows by the weathering steel that preparation method of the invention obtains:
Fig. 2 is the SEM pattern of the ferrite crystal grain at 1/4 thickness of weather-resistant steel plate, and through measuring, the average crystal grain of weathering steel is straight Diameter is 3.73 μm, and grain size number is 13.0 grades.As seen from the figure, section cooling step uses leading portion intensive and faster cooling side Formula can improve the mechanical property of final products by build up.
Fig. 3 is the precipitate SEM pattern of nanoscale even dispersion distribution.As seen from the figure, the nano-scale carbon of Ti, Nb, V, Mo Nitride is sufficiently precipitated, and can be further improved the mechanical property of weathering steel by strong precipitation strength effect.
Fig. 4 is the section SEM pattern for the corrosion products film that weathering steel is formed in atmospheric environment.As seen from the figure, weathering steel In atmospheric environment, the surface of weathering steel forms the double-deck corrosion products film；The internal layer of weathering steel is mainly the oxide of Cr, Ni, Fine and close corrosion products film is formed, passivation is produced to matrix, improves the corrosion resisting property of matrix；The outer layer master of weathering steel It to be the oxide and CuS of Fe, wherein CuS integrated distribution plugs outer layer corrosion products film in the hole of dimple shape rusty scale, The infiltration of atmosphere inner layer is prevented, to reduce the corrosion rate of matrix.Therefore, this bilayer that weathering steel has is anti-corrosion Mechanism, so that average corrosion rate of the weathering steel in atmospheric environment is less than 0.08g/ (m2·h)。
Embodiment 2
The present embodiment use method it is substantially the same manner as Example 1, unlike the initial feed chemical composition and The product specification of relevant technological parameter and the 550MPa being prepared grade Ultra-fine Grained high-strength weathering steel, average crystalline substance in preparation method Granularity and mechanical property.
Relevant technological parameter is as shown in following table 2-1 in the chemical composition and preparation method of the initial feed.It is described Product specification, mean grain size and the mechanical property of 550MPa grades of Ultra-fine Grained high-strength weathering steels are as shown in following table 2-2.
Relevant technological parameter in the chemical composition and preparation method of table 2-1 initial feed
The chemical composition of preparation method according to the present invention and the present embodiment initial feed is related in preparation method Technological parameter, product specification, mean grain size and the mechanical property of the 550MPa grade Ultra-fine Grained high-strength weathering steel being prepared It can be as shown in following table 1-2.
Product specification, mean grain size and the mechanical property of 550MPa grades of Ultra-fine Grained high-strength weathering steels of table 2-2

Claims (3)

1. a kind of preparation method of 550MPa grades of Ultra-fine Grained high-strength weathering steel, which is characterized in that the preparation method includes continuous casting Step, roughing step, finish rolling step, section cooling step and batch step；
The preparation method be initial feed is successively passed through continuous casting step, roughing step, finish rolling step, section cooling step and After batching step, final finished sheet billet is obtained；
The roughing step includes: that the continuous casting billet that the continuous casting step obtains is directly over M rack roughing mill under high pulling rate Group carries out the big pressure of M passage, obtains intermediate base；
The thickness of strand is 80-100mm；
The high pulling rate is 3-7m/min；
The M is positive integer, and M is not less than 3；
The single pass rolling reduction of the big pressure of M passage is 50-60%；
The roughing step and finish rolling step are full endless rolling；
The chemical composition of the initial feed includes: carbon, silicon, aluminium, manganese, copper, titanium, niobium, nickel, chromium, phosphorus, sulphur, nitrogen and iron；It is described first The mass fraction of each chemical composition of beginning raw material are as follows: 0.02-0.06% carbon, 0.1-0.4% silicon, 1.0-1.7% manganese, 0.01- 0.05% aluminium, 0.1-0.4% copper, titanium 0.04-0.08%, niobium 0.02-0.05%, nickel 0.1-0.3%, chromium 0.3-0.7%, phosphorus≤ 0.015%, sulphur≤0.003%, nitrogen≤0.004%, surplus are iron；
The thickness specification of the finished sheet base is 1.2-1.4mm, width specifications 1500mm, and mean grain size reaches 13.0- 13.5 grades；Yield strength >=550MPa of the finished sheet base, tensile strength >=680MPa, elongation > 10.0%, Qu Qiang Than < 0.94,180 ° of performance qualifications of clod wash, weatherability is equivalent to corten-A；
The preparation method further includes intermediate base processing step；
The intermediate base processing step is after the roughing step；
The intermediate base processing step includes: that the intermediate base for obtaining the roughing step is placed in induction heater and quickly heats up to Temperature T1, the intermediate base that obtains that treated；
The temperature T1It is 1100-1200 DEG C；
The finish rolling step includes: that treated that intermediate base carries out the pressure of N passage to described using N rack mm finishing mill unit, is obtained Sheet billet；The N is positive integer, and N is not less than 5；
Finishing temperature is 800-850 DEG C in the finish rolling step；
The drafts of the single pass pressure of the N passage pressure is 30-40%；
The section cooling step includes: that the sheet billet is passed through the laminar cooling system equipped with high water tank, takes leading portion The sheet billet is cooled to coiling temperature T by the intensive type of cooling2, obtain cooling sheet billet；
The step of batching includes: by coiling process, coiling temperature T when batching after the cooling sheet billet progress bundling2, batch After be air-cooled to room temperature, obtain final finished sheet billet；
In the section cooling step, cooling velocity is 50% or more；
The coiling temperature T2It is 620-660 DEG C.
2. a kind of preparation method of 550MPa grades of Ultra-fine Grained high-strength weathering steels according to claim 1, which is characterized in that institute Stating preparation method further includes dephosphorization step, and the dephosphorization step is placed in front of the finish rolling step.
3. a kind of preparation method of 550MPa grades of Ultra-fine Grained high-strength weathering steels according to claim 1 or 2 is in ESP production line On application, which is characterized in that the ESP production line overall length be 180-210m；The ESP production line continuous casting step to batch step The rapid time used is 6-10min.
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CN108486466B (en) * 2018-04-23 2019-11-19 马钢(集团)控股有限公司 A kind of yield strength 550MPa grade high ductility weather-resistant steel plate and preparation method thereof
CN109338212B (en) * 2018-09-26 2019-11-26 武汉钢铁有限公司 Using the yield strength >=550MPa thin gauge weathering steel and method of short route production
CN109266960B (en) * 2018-09-26 2019-11-26 武汉钢铁有限公司 Using the tensile strength >=800MPa thin gauge weathering steel and method of short route production
CN109881091B (en) * 2019-02-21 2021-06-15 江苏沙钢集团有限公司 High-strength weather-resistant steel thin strip and production method thereof
CN111101071B (en) * 2020-02-25 2021-04-13 湖南华菱涟源钢铁有限公司 High-strength weathering steel and production method thereof
CN111702010B (en) * 2020-06-23 2022-03-11 中冶赛迪工程技术股份有限公司 Production process of thin strip by continuous casting and rolling
CN112176259A (en) * 2020-10-14 2021-01-05 邯郸钢铁集团有限责任公司 550 Mpa-grade high-strength weathering steel and production method thereof

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CN106367686A (en) * 2016-08-30 2017-02-01 日照宝华新材料有限公司 Method of producing weathering steel by thin slab casting and rolling process based on ESP
CN106702283A (en) * 2016-12-30 2017-05-24 日照宝华新材料有限公司 Method for producing thin-gauge S355J0W steel based on ESP sheet billet continuous casting and rolling process

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