CN107365940B - A kind of preparation method and application of 700MPa grades of Ultra-fine Grained high-strength weathering steel - Google Patents
A kind of preparation method and application of 700MPa grades of Ultra-fine Grained high-strength weathering steel Download PDFInfo
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/02—Ferrous alloys, e.g. steel alloys containing silicon
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
- C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
- C21D8/0221—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the working steps
- C21D8/0226—Hot rolling
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- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
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- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/04—Ferrous alloys, e.g. steel alloys containing manganese
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- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/06—Ferrous alloys, e.g. steel alloys containing aluminium
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- 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
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- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
- C22C38/44—Ferrous alloys, e.g. steel alloys containing chromium with nickel with molybdenum or tungsten
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- 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
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- 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
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- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
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- 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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- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D2211/00—Microstructure comprising significant phases
- C21D2211/005—Ferrite
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Abstract
The present invention relates to a kind of preparation method and applications of 700MPa 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
Technical field
The invention belongs to metallurgical technology fields.More particularly to a kind of preparation method of 700MPa grades of Ultra-fine Grained high-strength weathering steel
And its 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 700MPa, 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 and 700MPa grades surpass using traditional process
High-strength steel sheet, the production for railcar and boxcar.In contrast, China is in light weight material in automobile, especially
High-strength weathering steel research and development are started late with application, such as currently on the market using more beam steel be mostly 510MPa with
610MPa grades (tensile strength), and weather resistance is poor.But, as automobile high-strength weathering steel is recognized by domestic some iron and steel enterprises
The continuous intensification known, had taken up the exploitation and popularization of high-strength weathering Automobile Plate, 700MPa grade high-strength is weather-proof thin in recent years
The research and development of slab become major steel mill and associated vehicle manufacturer focus of attention.
Currently, the industrial production of 700MPa grades of high-strength hot-strips mostly uses the rolling of sheet billet list base or semi-endless rolled work
Skill, traditional mode of production process are as follows: → pickling → cold rolling is batched in continuous casting → slab reheating → roughing → finish rolling → section cooling →
→ annealing.As this rolling mill practice is previous in roughing using 200-280m long rolling bottom formula furnace or induction heater to continuous casting billet into
Row heating, and cocurrent is carried out 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 700MPa 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 700MPa 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 be by initial feed successively by continuous casting, roughing, finish rolling, section cooling and after batching step,
Obtain the final finished sheet billet of 700MPa grades of Ultra-fine Grained high-strength weathering steels；
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 1.2-3.5mm, width specifications 1500mm.
Further, finishing temperature is 810-860 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 refinement increases dislocation density, increases shape in addition, the low certifiable austenite of finishing temperature is not being rolled in crystal region
Become 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 580-660 DEG C.
Further, in the section cooling step, cooling velocity is 75% or more.
Further, the section cooling step uses the intensive type of cooling of leading portion, and cooling velocity is 75% 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 T2, 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.
Further, the roughing and finish rolling step are full endless rolling.
A kind of application of the preparation method of 700MPa 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 700MPa 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 13.5~14.0 it is super
Fine grain high-strength weathering steel.
Further, the chemical composition of the initial feed include: carbon, silicon, aluminium, manganese, copper, titanium, niobium, vanadium, molybdenum, nickel, chromium,
Phosphorus, sulphur, nitrogen and iron；
The mass fraction of each chemical composition of initial feed are as follows: 0.02-0.08% carbon, 0.05-0.35% silicon, 1.0-
1.7% manganese, 0.01-0.05% aluminium, chromium, 0.1-0.4% copper, 0.02-0.08% titanium, 0.01-0.05% niobium, 0.02-0.08%
Vanadium, 0.08-0.20% molybdenum, 0.05-0.30% nickel, 0.3-0.6% chromium, phosphorus≤0.015%, sulphur≤0.006%, nitrogen≤
0.005%, surplus is iron.
Further, the final finished sheet billet dimensions is 1.2-3.5mm × 1500mm, is organized as single-phase iron element
Body, mean grain size reaches 13.5-14.0 grade, and shows surface and core crystal grain is thicker, the thinner tissue spy of crystal grain at 1/4 thickness
Point.At room temperature, precipitate mainly includes (Ti, Nb) C, (Ti, Nb) N, (Ti, Mo) C and a small amount of (Ti, V) C, having a size of 20~
300nm etc..In atmospheric environment, steel slab 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 0.02-0.08% 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 0.05-0.35% in the initial feed, is used as ferrite former, rises
To the effect of solution strengthening, in addition low Si design 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.
Titanium (Ti) in the initial feed, neodymium (Nb), vanadium (V) mass fraction select 0.02-0.08%, 0.01- respectively
0.05%, 0.02-0.08%, it is mainly the precipitation using carbonitride particle that micro titanium (Ti), neodymium (Nb), vanadium (V), which is added,
Strengthen, to guarantee the intensity of steel.
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, excessively high Nb content be easy to cause mixed crystal.And since the content of C, N in steel are lower, excessively high Ti,
Nb, V content can not play enough invigoration effects, will increase the cost of steel instead.In addition, micro Ti, Nb, V are added in steel
The recrystallization temperature of steel can be improved in element, enables steel that can complete to roll while obtaining storage large deformation at a higher temperature
Deformed austenite tissue, and then tiny phase-change organization is obtained, the intensity of steel is improved by refined crystalline strengthening.
The mass fraction of molybdenum (Mo) selects 0.08-0.20% in the initial feed, and effect is to improve the expansion of carbon atom
Property is dissipated, promotes the combination of titanium (Ti), neodymium (Nb), vanadium (V) and carbon (C), to promote the precipitates such as TiC, NbC, VC with molybdenum (Mo)
Complex form be precipitated, i.e., precipitate mainly includes (Ti, Nb) C, (Ti, Nb) N, (Ti, Mo) C and a small amount of (Ti, V) C, size
Between 20~300nm.In addition, molybdenum (Mo) can also refine the size of precipitate.
Chromium (Cr) in the initial feed, nickel (Ni), copper (Cu) mass fraction select 0.3-0.6%, 0.05- respectively
0.30%, 0.1-0.4%, chromium (Cr) and nickel (Ni) are primarily used to form fine and close internal layer corrosion products film, generate to matrix blunt
Change effect, copper (Cu) plug the hole in dimple shape rusty scale mainly with the formal distribution of CuS in outer layer corrosion products film, hinder
The infiltration for having stopped etchant gas inner layer, passivation and outer layer to matrix form corrosion products film and prevent etchant gas inside
Both infiltrations of layer act synergistically to reduce the corrosion rate of matrix.
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≤0.006% 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≤0.005% 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 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, V, Mo is sufficiently precipitated, by strong
Precipitation strength effect further increase the mechanical property of steel.
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 >=700MPa, tensile strength 800-900MPa, elongation > 12.0%, yield tensile ratio < 0.92, clod wash
180 ° of performance qualifications.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 700MPa grades of Ultra-fine Grained high-strength weathering steels of the invention has following advantageous effects:
(1) preparation method of the invention can strengthen tissue and the precipitation of final finished sheet billet, improve final finished thin plate
The mechanical property of base.
(2) application of the preparation method of a kind of 700MPa 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 13.5~14.0
Ultra-fine Grained high-strength weathering steel.
(3) the weather-proof steel surface and core that method of the invention obtains are thicker, 1/4 it is thick relatively locate thin tissue signature make it is thin
Slab has good cold forming capability, and good atmospheric corrosion resistance increases the service life of weathering steel.
(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；Production procedure can be shortened again, and before shortening production procedure
It puts, improves the surface quality of weathering steel, reduces the thickness specification of weathering steel, realize the technical effect of " with hot Dai Leng ", improve
The production efficiency of weathering steel reduces weathering steel production cost, while reducing production energy consumption, reduces discharge, reaches resource-effective, ring
The effect of border friendly production.
(5) the intermediate base of method of the invention after roughing step, directly carries out finish rolling to it after processing, without
Process flow is shortened to the reheating link of slab before roughing in traditional handicraft, reduces energy consumption, also obtains higher list
Machine yield.
(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 deformation energy storage, improves subsequent cooling procedure ferrite in addition, finishing temperature is lower to increase dislocation density
Forming core rate, and prevent recrystallization after Austenite Grain Growth.
(9) in method of the invention laminar flow cooling step use the intensive type of cooling of leading portion, and cooling velocity be 75% 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 700MPa grades of Ultra-fine Grained high-strength weathering steel to apply in ESP production line
On, as Figure 1-Figure 4.Its process flow 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.
It batches step by continuous casting → roughing → centre base processing → finish rolling → section cooling → in ESP production line and obtains into
Product sheet billet.
The continuous casting billet that middle Baogang's water is formed by straight circular-arc type continuous casting machine 2 with a thickness of 90mm.
The continuous casting billet is directly entered 3 rack roughing mills 3 in the case where high pulling rate is 3-7m/min and carries out carrying out the big pressure of 3 passages
Under；
The drafts of the big pressure of single pass of the big pressure of 3 passage is 50%-60%.
The inlet temperature of the roughing is 1156 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 T1Treated as described
The entry temperature at finishing of intermediate base.
The temperature T1It is 1162 DEG C.
The finish rolling step includes: intermediate base temperature after the treatment when being 1162 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 2.5mm, width specifications 1500mm.
In the section cooling step, cooling velocity is 75% or more.
The finishing temperature of the finish rolling step is 815 DEG C.
The drafts of the single pass pressure of the N passage pressure is 30%-40%.
The section cooling step includes: the sheet billet for obtaining the finish rolling step, by being furnished with the layer of high water tank
Flow cooling system 10, takes the intensive type of cooling of leading portion, and the sheet billet is cooled to coiling temperature T2, obtain cooling thin plate
Base.
The step of batching includes: to batch after the cooling sheet billet that the section cooling step obtains is carried out bundling
Journey, coiling temperature T2, it is air-cooled to room temperature after batching, obtains the final finished sheet billet.
The bundling process carries out bundling using high-speed flying shear 11.
The coiling process is batched using downcoiler 12.
The coiling temperature T2It is 638 DEG C
The preparation method further includes dephosphorization step, and the dephosphorization step is placed in front of the finish rolling 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.
The roughing and finish rolling step are full endless rolling.
Relevant technological parameter is as shown in table 1 below in the composition of the initial feed, mass fraction and preparation method.
Relevant technological parameter in the composition of table 1-1 initial feed, mass fraction and preparation method
Composition, mass fraction and the preparation 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 in method, the 700MPa grade Ultra-fine Grained high-strength weathering steel being prepared (with
Lower abbreviation 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 700MPa grades of Ultra-fine Grained high-strength weathering steels of table 1-2
The weathering steel final products that the present embodiment is obtained by preparation method of the invention carry out sampling and are placed in SEM (scanning
Electron microscope) on observe pattern, and be analyzed as follows:
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 2.84 μm, and grain size number is 13.5 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 method that the present embodiment uses is substantially the same manner as Example 1, only the difference is that the composition of the initial feed, quality
The product of relevant technological parameter and the 700MPa being prepared grade Ultra-fine Grained high-strength weathering steel is advised in score and preparation method
Lattice, mean grain size and mechanical property are different.
Relevant technological parameter is as shown in following table 2-1 in the composition of the initial feed, mass fraction and preparation method.
Product specification, mean grain size and the mechanical property of the 700MPa grades of Ultra-fine Grained high-strength weathering steel are as shown in following table 2-2.
Relevant technological parameter in the composition of table 2-1 initial feed, mass fraction and preparation method
Composition, mass fraction and the preparation 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 in method, the 700MPa grade Ultra-fine Grained high-strength weathering steel being prepared
Product specification, mean grain size and mechanical property are as shown in following table 1-2.
Product specification, mean grain size and the mechanical property of 700MPa grades of Ultra-fine Grained high-strength weathering steels of table 2-2
Claims (9)
1. a kind of preparation method of 700MPa 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 is to obtain initial feed successively by continuous casting, roughing, finish rolling, section cooling and after batching step
The final finished sheet billet of 700MPa grades of Ultra-fine Grained high-strength weathering steels；
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 M is positive integer；
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, vanadium, molybdenum, nickel, chromium, phosphorus, sulphur, nitrogen and iron；
The mass fraction of each chemical composition of initial feed are as follows: 0.02-0.08% carbon, 0.05-0.35% silicon, 1.0-1.7%
Manganese, 0.01-0.05% aluminium, chromium, 0.1-0.4% copper, 0.02-0.08% titanium, 0.01-0.05% niobium, 0.02-0.08% vanadium,
0.08-0.20% molybdenum, 0.05-0.30% nickel, 0.3-0.6% chromium, phosphorus≤0.015%, sulphur≤0.006%, nitrogen≤0.005%,
Surplus is iron；
In atmospheric environment, the surface of the weathering steel forms the double-deck corrosion products film；The internal layer of the weathering steel be mainly Cr,
The oxide of Ni, the two form fine and close corrosion products film, produce passivation to matrix, improve the corrosion resisting property of matrix；
The outer layer of the weathering steel is mainly the oxide and CuS of Fe, and wherein CuS integrated distribution blocks up in the hole of dimple shape rusty scale
Outer layer corrosion products film has been filled in, the infiltration of atmosphere inner layer is prevented, to reduce the corrosion rate of matrix.
2. a kind of preparation method of 700MPa grades of Ultra-fine Grained high-strength weathering steels according to claim 1, which is characterized in that institute
Stating 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.
3. a kind of preparation method of 700MPa grades of Ultra-fine Grained high-strength weathering steels according to claim 2, which is characterized in that institute
Stating 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, obtains sheet billet；
The N is positive integer；
The section cooling step includes: the sheet billet for obtaining the finish rolling step, cold by the laminar flow equipped with high water tank
But system takes the intensive type of cooling of leading portion, by the sheet billet to coiling temperature T2, obtain cooling sheet billet；
The step of batching includes: that the cooling sheet billet for obtaining the section cooling step carries out coiling process after bundling, volume
Coiling temperature T when taking2, it is air-cooled to room temperature after batching, obtains the final finished sheet billet；
The coiling temperature T2It is 580-660 DEG C.
4. a kind of preparation method of 700MPa grades of Ultra-fine Grained high-strength weathering steels according to claim 1, which is characterized in that institute
M is stated not less than 3.
5. a kind of preparation method of 700MPa grades of Ultra-fine Grained high-strength weathering steels according to claim 1, which is characterized in that institute
Stating high pulling rate is 3-7m/min.
6. a kind of preparation method of 700MPa grades of Ultra-fine Grained high-strength weathering steels according to claim 3, which is characterized in that institute
N is stated not less than 5.
7. a kind of preparation method of 700MPa 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.
8. a kind of any one of -7 preparation methods of 700MPa grades of Ultra-fine Grained high-strength weathering steel are raw in ESP according to claim 1
Application in producing line.
9. a kind of preparation method of 700MPa grades of Ultra-fine Grained high-strength weathering steels according to claim 8 is on ESP production line
Application, which is characterized in that the ESP production line overall length be 180-210m.
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| 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 |
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| CN111455287B (en) * | 2020-03-30 | 2021-09-17 | 南京钢铁股份有限公司 | 500 MPa-grade low-yield-ratio weather-resistant bridge steel and manufacturing method thereof |
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| JPS6056021A (en) * | 1983-09-06 | 1985-04-01 | Kawasaki Steel Corp | Production of grain oriented silicon steel sheet |
| CN1609257A (en) * | 2004-11-16 | 2005-04-27 | 武汉钢铁(集团)公司 | Acicular constituent high strength weathering resistant steel and producing method thereof |
| CN102168229A (en) * | 2010-02-25 | 2011-08-31 | 宝山钢铁股份有限公司 | Weather resistant steel plate and manufacturing method thereof |
| CN103290335A (en) * | 2013-05-21 | 2013-09-11 | 马钢(集团)控股有限公司 | High-strength and high-corrosion-resistance steel plate material with yield strength of 900 MPa and production method thereof |
| 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 |
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Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS6056021A (en) * | 1983-09-06 | 1985-04-01 | Kawasaki Steel Corp | Production of grain oriented silicon steel sheet |
| CN1609257A (en) * | 2004-11-16 | 2005-04-27 | 武汉钢铁(集团)公司 | Acicular constituent high strength weathering resistant steel and producing method thereof |
| CN102168229A (en) * | 2010-02-25 | 2011-08-31 | 宝山钢铁股份有限公司 | Weather resistant steel plate and manufacturing method thereof |
| CN103290335A (en) * | 2013-05-21 | 2013-09-11 | 马钢(集团)控股有限公司 | High-strength and high-corrosion-resistance steel plate material with yield strength of 900 MPa and production method thereof |
| 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 |
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