CN1296498C - In-line process for the recrystallization of solidified coarse strips in carbon steel and in low-alloyed steel and so obtainable strips having a highly checked microstructure - Google Patents
In-line process for the recrystallization of solidified coarse strips in carbon steel and in low-alloyed steel and so obtainable strips having a highly checked microstructure Download PDFInfo
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- CN1296498C CN1296498C CNB02825466XA CN02825466A CN1296498C CN 1296498 C CN1296498 C CN 1296498C CN B02825466X A CNB02825466X A CN B02825466XA CN 02825466 A CN02825466 A CN 02825466A CN 1296498 C CN1296498 C CN 1296498C
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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
- C21D8/021—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips involving a particular fabrication or treatment of ingot or slab
- C21D8/0215—Rapid solidification; Thin strip casting
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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
- C21D8/0278—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips involving a particular surface treatment
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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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- 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
- C21D8/0263—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the heat treatment following hot rolling
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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
- C21D8/0247—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the heat treatment
- C21D8/0273—Final recrystallisation annealing
-
- 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
- C21D9/00—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
- C21D9/52—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for wires; for strips ; for rods of unlimited length
Abstract
The invention refers to an in-line process for the making of strips in carbon steel and in low-alloyed steel by a recrystallization (rolling and annealing) treatment of solidified coarse strips, having a coarse structure, aimed at inducing an advanced recrystallization of the material with homogenizing, refining and checking of the end microstructure, and the entailed improvement of the mechanical properties, in terms of a mix of strength and ductility/cold formability, and of the reproducibility thereof. This process comprises the following steps: casting, in a twin-roll continuous casting machine (A) of strips having a thickness ranging from 1 to 6 mm and a composition, expressed as percent by mass, comprising the following components: 0.02-0.20 C; 0.1-1.6 Mn; 0.02-2.00 Si; <0.05 A1; <0.03 S; <0.1 P; 0.01-1.5 Cr; 0.01-0.5 Ni; <0.5 Mo; 0.003-0.012 N, with substantially Fe q.s. to 100; controlled cooling of the strip in the section comprised between the casting rolls and a rolling system (E); holding the strip at a controlled temperature in an insulated system (F) comprised between an outlet of the rolling system (E) and an inlet in a heating system (G); heating the strip with said heating system (G) at temperatures ranging from 670 to 1150 DEG C for times ranging from 5 to 40 s, so as to attain a >95% b/v strip recrystallization; - controlled cooling in the section comprised between an outlet of said heating system (G) and a wrapping system.
Description
Technical field
The present invention is applicable to that principal character is to produce large size crystal grain (150-1500 μ m) in solidifying thick product by a kind of pair of roller or single roller and band machine directly continuous casting and the carbon steel and low alloy steel band made.
The present invention relates at band during the roll passage transmits, before coiler twines, solidifying the on-line Control recrystallize processing that the coarse-grain band carries out.Particularly carry out online and the rolling and annealing of successive fast (rapid heating and be incubated very short time at preset temperature), therefore, in fact other microstructure compositions (as ferrite) of work hardening obtain perfect recrystallization in austenite and the distortion in front.Rolling and annealing can be in austenite or ferrite stable status, or carries out at austenite and all stable mixing phase region of ferrite.
The present invention relates to use the thick band of continuous casting as starting material, and use the conventional online recrystallization method, make and universal or special hot rolling or the cold rolling thickness range suitable manufacture method at steel band and the thin plate of 4.5-0.7mm with annealing product.
Background technology
Thereby existing several methods that make initial austenite uniform crystal particlesization and refinement improve the mechanical property of continuous casting band by hot mechanical treatment make progress and obtain patent.
EP 0707908A1 describes a kind of being used at inert gas atmosphere in detail, as Ar (argon) or N
2The double roller continuous casting device of casting carbon steel band in (nitrogen).This band is subjected to online hot rolling (from 850 ℃ to 1350 ℃), and reduction in thickness is 5% to 50%, then cooling.Because hot rolling reduces grain-size (degree), the light sheet products of gained has good intensity and ductility.
Other structure refinement method (JP 61689846 and JP 63115654) relates to does not have the online thermal treatment of hot rolled, before final cooling and spooling, has at least a pair of heavy phase to become.Make band stand single or the multiple heat cyclical patterns: cooling, heating, cooling cause above-mentioned phase transformation.Carbon steel and low alloy steel for the thick Product Status of casting, at EP 0707908, illustrated among EP 0818545 and the JP 3249126 it has been carried out online heat-treating methods and device, wherein before or after the thermo compression that the thickness of the thick band of casting is chosen wantonly, this band once cools off, heat in stove subsequently, its purpose is its tissue of nucleation mechanism refinement by austenite crystal new after the phase transformation of ferrite phase region.Above-mentioned some technology is improved mechanical property except thinning microstructure, and as intensity, outside ductility and the toughness, its target also is to make band to have suitable surface smoothness (roughness).
WO 95/13155 (ISHIKAWAJIMA and BHP) has also illustrated a kind of online thermal treatment of casting the carbon steel band, and its purpose is to verify this as cast condition band microstructure.Especially, after 900～1100 ℃ of optional single pass draught (20-50%), this cast strip is cooled to be lower than that austenitic transformation takes place is below the ferritic temperature, then at the stove internal heating of＜1200 ℃ of temperature up to material reaustenitizing (online normalizing).Therefore, austenite crystal through last cooling of checking band and spooling, can be obtained providing the tissue of sufficient intensity and the abundant refinement of ductile by refinement.
EP 0776984 (Japanese steel company) has reported a kind of method and the relevant device thereof of making the sheet metal strip volume from the continuous casting system of band continuously, and the step that comprises is: thermal distortion, reduction in thickness＞30%; In the nonoxidizing atmosphere of 800-1250 ℃ (being preferably 1100-1250 ℃) in the thermal treatment of stove internal heating; Speed with 20-40 ℃/S is cooled to 100 ℃; Pickling; Band spooling/shearing.The main purpose of this invention is that main foudry line and band pickling-side cut-final heat-treatment lines are coupled together, so that carry out a single consecutive steps, wherein pickling, side cut, band spooling/shear line can be connected to Strip casting-rolling-heat-treatment lines independently.Though this invention available metal comprises ordinary steel and special steel, unique example of report relates to a kind of stainless steel.
EP 0760397 (Japanese steel company) has also announced the stainless device of a kind of manufacturing, carries out a kind of method that comprises the following steps: casting, cooling, differing temps thermal distortion (rolling), realize perfect recrystallization by heating and cooling.Above-mentioned some method and other similar approach require to introduce one or more optional cooling systems, and a milling train seat, and reheating furnace in the middle of, this reheating furnace are positioned at upstream or the downstream that band is delivered to the milling train seat on the roll passage of wind.
The great majority experiment of above-mentioned carbon steel and low alloy steel all relates to the online thermal treatment or the hot mechanical treatment that can produce austenite-ferrite-austenite continuous phase transistion, so that before the cooling of band spooling, obtain the austenite structure of a kind of homogenizing and refinement, so that it is similar with traditional hot rolled band as far as possible.
Prior art was not instructed, by rolling at ferrite, austenite or mixing phase region, and at a subcritical phase region (＜Ac
3Treatment temp in the stove) directly anneal and develop a kind of online recrystallize and handle, by the carbon steel and low alloy steel product that the thick band of continuous casting and solidifying obtains having required mechanical property and processing performance, these products and hot rolling or cold rolling suitable with anneal band and sheet material.
The online recrystallize technology of minority always relates to the extremely slow high quality steel (stainless steel) of speed recrystallize, therefore, requires treatment temp just above 1050 ℃ usually, so that realize tangible recrystallize in the short period of time.
Obviously faster than stainless carbon steel, solidifying in the thick band very, the existence of coarse grain also suppresses recrystallization process for its recrystallize kinetics.Therefore, though solidify band in high temperature deformation, and in a single pass, be subjected to high distortion, its recrystallize is only partial, and in fact some crystal grain keep its initial how much patterns.Obtain some mechanical property and desired other alloying elements of microstructure if in carbon steel, be incorporated as, as Si, Cr, Ni and/or microalloy element, as V and Nb,＜950 ℃ temperature, it is non-existent that recrystallize is actually.Should consider, in prior art system, cause band suitably to cool off, simultaneously also because rolling speed very low (long duration of contact) and single pass draught usually very big (greater than the contact arc line length) with contacting of water-cooled roll.After rolling, cast thick thin strip (＜3.5mm) at once representative temperature general＜1050 ℃, usually＜1000 ℃, in addition at band in still air refrigerative situation, drop in several seconds＜950 ℃.Therefore, in hitherto known technology, the recrystallize of carbon steel and soft steel casting coarse texture is always partial, is mainly the heterogene structure of the big crystal grain that should not obtain required final performance.
An object of the present invention is to provide one make the carbon steel and low alloy steel band at Wiring technology, before twining, during the roll passage transmits, handle solidifying the recrystallize that the coarse-grain band carries out a control at coiler.
Particularly carry out online, annealing (rapid heating rolling with quick successive, at the preset temperature isothermal treatment for short time, so that make the austenite and/or the approximate recrystallize fully of ferrite of work hardening when being out of shape) and the cooling (comprising optional Direct Electroplating) before coiler twines.
A kind of manufacture method of steel band of the present invention can realize this purpose.
According to a most preferred embodiment, this novel method comprises the following steps:
The cast thickness scope is at 1 to 6mm band in a kind of double-roller continuous casting machine (A), and by mass percentage, its composition is: 0.02-0.20C, 0.1-1.6Mn, 0.02-2.00Si,＜0.05Al,＜0.03S,＜0.1P, 0.01-1.5Cr, 0.01-0.5Ni,＜0.5Mo, 0.003-0.012N all the other are Fe and unavoidable impurities;
This band of section controlled chilling between a casting roll and a rolling system (E);
With above-mentioned rolling system (E), arrive (Ar at 1150 ℃
1-100) ℃ temperature range makes above-mentioned cast strip thermal distortion, is 15-80% until reduction in thickness, and above-mentioned thermal distortion is selected from following one group of technology:
-＞Ar
3Temperature is also rolling at complete austenite phase region, Ar
3Be to cool off austenite phase transformation continuously to begin temperature;
-＜Ar
1Temperature and complete ferrite phase region are rolling;
-at Ar
3To Ar
1Temperature range and austenite phase and ferritic phase coexisting state are rolling.
In the adiabatic system (F) between the inlet of rolling system (E) outlet and a heating system (G), and, make the band insulation at a controlled temperature.
With said heating system (G), 670 ℃ to 1150 ℃ temperature ranges, the heating band, the time is 5-40s, therefore,＞95% volume band recrystallize.
In said heating system (G) outlet with a kind of a plurality of coilers (N, controlled chilling band between winding system P) arranged.
Another object of the present invention provide with above-mentioned technology manufacturing, thickness is carbon steel and stainless strip 4.5～0.7mm, that have predetermined microstructure characteristic, this band can produce the following performance that is suitable for various Application Areass:
Non-abominable application as cold formability crooked and that draw, is used for the part of fabricator electrical appliance (refrigerator lid, scatterer, refrigerating system) and building industry (as gutter, window-frame, garage door, top ceiling etc.).
Cold shaping (as wheel rim) in abominable the application.
Structure applications (as protect block, auto parts, container, etc.).
Below, by explanation, will the present invention be described better in conjunction with the accompanying drawings to as an example a nonrestrictive embodiment, in the accompanying drawing:
Fig. 1 is used for the continuous caster of production thin strip of the present invention and a simple synoptic diagram of online recrystallize of band and high controlled chilling device.
Fig. 2 is online recrystallize and the refrigeration cycle figure that is used to cast thick band.
Fig. 3 and Fig. 4 band microstructure of optics microscopic examination.
With reference to figure 1, method of the present invention provides the continuous caster (A) that uses a kind of pair of roller or single roller/Cast Strip mould, and principal character is to form large size crystal grain (150-1500 μ m) in solidifying thick product.Be provided with refrigerating unit (B and the D) band that is used for by a kind of controllable manner cooling strip material in its direct downstream and pass through these devices continuously by the known pinch roll of this body structure (C) guiding.
Solidifying and when mould (A) was extracted out, band was subjected to a suitable power, for example acting on the power of two rollers, therefore limiting the generation of shrinkage cavity.Two surfaces of cast strip are cooled off, to reduce the growth of austenite crystal and surface oxide layer.The refrigeration cycle of determining the as cast condition steel band is to work to teeming speed, flow and active cooling surface long-pending (module).That above-mentioned a pair of cooling system B and D have is individual drive, transformable at independent section, can cause the band speed of cooling to reach the module of 200 ℃/S.
In said module, by realizing cooling from the selected type of cooling of a following prescription case: natural air, pressurized air, spray rare gas element, air-water, water or above-mentioned combination from inert chamber.
Downstream at cooling system (D), be provided with a rolling system of forming by one or more milling train seats (E), in one or more passages, the milling train seat can be finished total draught of 15-80%, be reduced to the size of allowing so that solid is shunk the residual pore that causes, and make the work hardening of organizing of instantaneous deformation existence.
These milling train seats are set as close as possible, so that the time quite short (less than obtaining 50% volume recrystallize required time) between passage, and make accumulated deformation in material (accumulated deformation is big more, and material recrystallize and softening kinetics are fast more).
More specifically, can make cast strip generation thermal distortion by means of two coherent milling train seats, each milling train seat provides the draught of 15-40%.
In addition, can be provided with an automotive quick-heat system (R), so that the temperature that enters the band of rolling system (E) according to the composition of steel and the hot mechanical cycles control carried out.
This automotive quick-heat system (R) is positioned at the downstream of controlled chilling system (D).
In the outlet of rolling system (E), also be provided with a system that constitutes by adiabatic air channel (F), interior logical natural air, rare gas element or its combination, its purpose is the band of the stove (G) that is about to enter next-door neighbour's rolling system (E) is incubated.Especially, under the mutually rolling situation of austenite, this adiabatic section prevents that temperature is reduced to Ar
3Below, and prevent from before austenite recrystallization, to begin phase transformation.
The stove of induction type, gaseous type or other of this types (G) can be worked under reduction or nonoxidizing atmosphere, and (less than 12s) brings up to 670-1150 ℃ of scope to strip temperature fast, is easy to realize in the time of insulation 5-40s the approaching recrystallize (95% volume) completely of material.As shown in Figure 2, annealing temperature is selected in austenite phase region (the austenite phase region is rolling), or ferrite phase region (the ferrite phase region is rolling), or ferrite and austenite coexistence mixing phase region (ferrite or mixing phase region are rolling).
In the outlet of stove, be provided with cleaning system (H), be used for removing by local or overall reductive oxide compound of furnace atmosphere or oxide residue from strip surface.
In the downstream of cleaning system (H), along lead to coiler (N, on roll passage P), be provided with one group at least three controlled chilling modules (I, L, M).These modules can make band change in the rate of cooling of each independent section, its variation range from 800 ℃/s (supper-fast cooling) to 0.01 ℃/s (thermal insulation).
According to the strip temperature that detects with appropriate device at stove exit, and, determine the refrigeration cycle of band according to the microstructure characteristic of the chemical analysis composition that depends primarily on gas crystal grain physical size difficult to understand and steel, thereby the development tissues needed.On the roll passage, in each module, be provided with other temperature measuring equipments (as pyrometer) that to monitor thermal cycling.Producing by multiple composition the situation of the polyphase microstructure that constitutes as polygonal ferrite, bainite, martensite and/or residual austenite, its thermal cycling quite complicated (as quickening cooling, cool off in the air, twine).
An assembly in the cooling module also can be to strap electroplating.
Yet the temperature that is preferably in 900-150 ℃ is twined band.
Use the steel of following ingredients (by mass percentage) to carry out various laboratories and full-scale shop test:
0.02-0.20C, 0.1-1.6Mn, 0.02-2.00Si,＜0.05Al,＜0.03S,＜0.1P, 0.01-1.5Cr, 0.01-0.5Ni,＜0.5Mo, 0.003-0.012N, randomly also have:＜0.03Ti,＜0.10V,＜0.035Nb,＜0.005B, all the other are Fe and unavoidable impurities.
These test main points are:
(a) with to solidify macrostructure similar, the crystal grain of casting thick band has bigger mean sizes (＞150 μ m), and often is column crystal.
(b) adopt the initial crystalline substance of such size and above-mentioned chemical analysis composition, at on-line rolling state (15-40% draught, the rate of deformation 10-35S of the bent type of the thick band of casting
-1, texturing temperature 1100-1150 ℃) and can not activate dynamic recrystallization.
(c) will cause static state at 1000-1150 ℃ of 30-40% draught but still be that partial recrystallize still keeps significant coarse-grain percentage (＞50% volume).In fact, along with hot rolling stops the reduction of back strip temperature, original just very slowly austenite recrystallization kinetics become slower.This has just produced the heterogeneity of microstructure, and the checking/controlled chilling subsequently and the effect of winding can not make its equilibrium.
(d) by reducing the texturing temperature of austenite phase region, static recrystallize is suppressed, and in phase transformation subsequently, except that the initial austenite edge, in the deformation bands coarse-grain, the ferrite nucleation takes place all.Its net result be to a certain degree refinement but still be non-uniform tissue.
(e) crystal grain on the nearly surface of as cast condition and rolling thick band thin than center thickness district, this be since during on-line rolling the ununiformity of thickness deformation and thermograde cause.
(f) that omit after the on-line rolling or incomplete recrystallized, and have the low homogeneity of inadequate refinement and final microstructure concurrently, be the structure applications (requiring high strength and suitable toughness) of development band and directly application, in a key factor of construction industry and the alternative cold-strip of household appliance technical field.
(g) after the hot rolling stage (at 950-1150 ℃ greater than 15% distortion), at once be introduced in the online annealing of 1050-1100 ℃ of temperature, even its composition is in a kind of low alloy steel of indicated ultimate, in time, also can realize having the austenitic near perfect recrystallization (＞95% volume) of extremely thick initial tissue less than 40s.
(h) very high temperature can be quickened static recrystallize really, but causes excessive recrystallize austenite grain size (＞120 μ m).
(i) according to rolling and in the annealing temperature institute cumulative distortion of using, after the on-line Control recrystallize was handled, austenite crystal was to wait axle and uniformly, and mean sizes is 50-120 μ m.Under the situation of＞10 ℃/s rate of cooling and＞700 ℃ of temperature windings, after the checking cooling, these austenite crystals produce the ferrite crystal grain that is of a size of 15-30 μ m.Under latter event, also can observe pearlite region, its percent by volume is relevant with the carbon content of steel.
(j) homogenizing by austenite structure, and strip temperature is in the homogenizing of length and width direction, this online recrystallize can reduce tissue (as Polygons, the tissue of aciculiform and other inevitable forms) variation, the repeatability that helps mechanical property is particularly for the direct application product that substitutes the traditional cold strip.
(k) for soft steel band (c＜0.06%), even if at the ferrite phase region, promptly at Ar
1To Ar
1-100 ℃ temperature range also can be cast the rolling of thick band, and does not have the problem of excessive rolling load.Distortion for ferrite phase region＞25%, carry out online annealing＜40s at 670-720 ℃, and twine band fast in such temperature, can obtain having the crystal grain of 30-60 μ m size and the ferritic structure of subgrain (lower yield value) and even distribution of carbides (not having lamellar perlite), be applicable to non-abominable cold shaping step, as crooked and draw.
At ferrite or mix phase region when rolling, even if the carbon steel band of 0.06-0.2% all can be annealed at short notice.In this situation, utilize close-to-critical range (Ac
1-Ac
3) annealing.According to outlet at stove, and finally organize aequum and type (for example bainite and high carbon martensite district according to being dispersed in existing ferrite, or bainite and remaining austenite district) controlled chilling before, needed carbon enrichment amount in the Ovshinsky scale of construction and the band is determined this temperature in the band.
By selecting the chemical analysis composition of steel, the online recrystallize of the thick band of casting of the present invention is handled and can be verified rolling and annealing temperature and online refrigeration cycle, has (polygon) ferrite such as axle such as grade, perlite and high carbon martensite needle-like carbide, clear and definite per-cent and/or bainite ferrite, the clear and definite per-cent/final microstructure remaining austenite district, suitable of clear and definite volume percent with development.Therefore, the different distributions of the microstructure component that heat that is obtained and handle to take place by recrystallize in stove and microstructure homogenizing can highly be verified provides the various combination of intensity, ductility and cold formability for band.
Especially, evaluated the performance with the product of the ferritic structure with 30-80 μ m equi-axed crystal and perlite or non-stratiform carbide, this tissue is to obtain from the online recrystallize that the austenite of the thick band of casting of the soft steel with very thick original texture (C＜0.06%) and ferrite carry out respectively.
Carried out containing Mn, the low alloy steel of Si and other elements chosen wantonly such as Cr is cast the online recrystallize of thick band and is handled and the controlled chilling processing, contain ferrite (＞55%) with development, the polyphase structure of bainite (5-40%) and dispersive high-carbon (1-15%C) martensitic regions.This tissue is characterised in that: for traditional polygonal ferrite/pearlitic structure, a high dislocation desity is arranged at the ferrite interface.The final material of gained has the stress-deformation curve of successive type, and good intensity and ductility over-all properties are arranged.Develop a kind of subcritical recrystallize of continuous casting band and handled, obtained having the microstructure of a considerable amount of remaining austenites (5-20%).
According to purpose of the present invention, some embodiment are disclosed below.
Example 1:
According to method of the present invention, use steel A to make the thick band of a kind of 1.6mm, the chemical analysis of steel A is reported in table 1.
The chemical analysis of table 1 steel A
| Steel | C | Mn | Si | Cr | Ni | Cu | Ti | Mo | S | P | Al | N |
| A | 0.048 | 0.73 | 0.28 | 0.07 | 0.07 | 0.18 | 0.01 | 0.02 | 0.002 | 0.008 | 0.005 | 0.0065 |
Molten steel casting in vertical continuous casting machine (A) with two roller molds and the average separating force of a 6t/m (ton/minute).Band is in mold outlet cooling, until reaching 1080-1100 ℃ temperature at the rolling system inlet.Producing the thickness total reduction is 3.5%.Shown in Fig. 2 is simple, carry out follow-up cooling and heating steps, the minimum temperature Tm that obtains the band in stove is 〉=850 ℃, and heating rate is 10 ℃/s, and maximum temperature is 1050 ℃, keeps the time of 10s.Outlet at stove is 15 ℃/s until twining the detection rate of cooling.Be wrapped in＞750 ℃ temperature carries out.The microstructure characteristic and the mechanical property of final band, as ferrite crystal grain mean sizes (d), perlite (P) %, minimum yield value (Re
L), strength at break (Rm), Re
L/ Rm ratio, elongation limit (A), report in table 2.The standard deviation and the ratio between the mean value of strength at break and elongation are respectively 2.5% and 3%.These values show the high verifiability of the final microstructure that online recrystallize causes.
The steel A band of table 2 final thickness 1.6mm
Microstructure characteristic and mechanical property
| d (□m) | P (％) | Re L (MPa) | Rm (MPa) | Rs/Rm (-) | A (％) |
| 17 | 2 | 260 | 365 | 0.71 | 28 |
Fig. 3 illustrates the typical microstructures of the band of opticmicroscope observation.
Obviously, produced a kind of ferritic structure with equi-axed crystal and pearlite region.
Example 2:
According to method of the present invention, use steel B, having made final thickness is the 1.6mm band, the chemical analysis of steel B is reported in table 3.
The chemical analysis of table 3 steel B
| Steel | C | Mn | Si | Cr | Ni | Cu | Ti | Mo | S | P | Al | N |
| B | 0.11 | 0.80 | 0.29 | 0.06 | 0.04 | 0.05 | 0.005 | 0.01 | 0.003 | 0.007 | 0.027 | 0.0042 |
Molten steel is cast in a vertical continuous casting machine with two roller molds and the average separating force of 5.5t/m.Band is in mold outlet cooling, until reaching 1080-1100 ℃ temperature at the rolling system inlet.Producing the total draught of thickness is 35%.Shown in Fig. 2 is simple, carry out follow-up cooling and heating steps, obtain the interior band minimum temperature Tm of stove and be 〉=850 ℃, heating rate is 8 ℃/s, and maximum temperature is 1050 ℃, and soaking time is 12s.At stove exit, until winding, detecting rate of cooling is 15 ℃/s.Be wrapped in＞750 ℃ temperature carries out.The microstructure characteristic and the mechanical property of final band, as ferrite crystal grain mean sizes (d), perlite P (%), minimum yield value (Re
L), strength at break (Rm), Re
L/ Rm ratio, elongation limit (A), report in table 4.The standard deviation of strength at break and elongation and the ratio between the mean value are respectively 3% and 3.5%.
The steel B band of table 4 final thickness 1.6mm
Microstructure characteristic and mechanical property
| d (□m) | P (％) | Re L (MPa) | Rm (MPa) | Rs/Rm (-) | A (％) |
| 14 | 10 | 270 | 390 | 0.69 | 24 |
Fig. 4 illustrates the typical microstructures with the band of optics microscopic.
Example 3:
According to method of the present invention, use steel B, made the thick band of a kind of 1.6mm.The chemical analysis of steel B is reported in table 3.
Molten steel is cast in a vertical continuous casting machine with two roller molds and the average separating force of 6t/m.Band is in mold outlet cooling, until reaching 690 ℃ temperature at the rolling system inlet.The total reduction of the thickness of generation 35%.Shown in Fig. 2 is simple, carry out follow-up cooling and heating steps, the minimum temperature Tm that obtains band in the stove is 〉=670 ℃, and heating rate is 5 ℃/s, and maximum temperature is 720 ℃, soaking time 15s.
At stove exit, until winding, detecting rate of cooling is＜0.5 ℃/s.Be wrapped in 〉=700 ℃ temperature carries out.The microstructure characteristic and the mechanical property of final band are as the mean sizes (d) of ferrite crystal grain, minimum yield value Rc
L, strength at break (Rm), Re
L/ Rm ratio, elongation limit (A), report in table 5.
The online recrystallize of table 5, ferritic phase rolls
System, the steel A band of final thickness 1.6mm
Microstructure characteristic and mechanical property
| d (□m) | Re L (MPa) | Rm (MPa) | Rs/Rm (-) | A (％) |
| 30 | 370 | 450 | 0.82 | 32 |
It is to have a kind of ferritic structure that disperses non-stratiform carbide that opticmicroscope is observed clear and definite gained band.
Example 4
According to method of the present invention, use steel C, made a kind of band of 2.4mm final thickness.The chemical analysis of steel C is reported in table 6.
The chemical analysis of table 6 steel C
| Steel | C | Mn | Si | Cr | Ni | Cu | Ti | Mo | S | P | Al | N |
| C | 0.15 | 1.55 | 1.42 | 0.10 | 0.05 | 0.1 | 0.005 | 0.02 | 0.005 | 0.092 | 0.03 | 0.054 |
Molten steel is cast in a vertical continuous casting machine with two roller molds and 6.5t/m separating force.Band is in mold outlet cooling, and heating then is until reaching 840-860 ℃ temperature at the rolling system inlet.Produce the draught of 40% total thickness.Shown in Fig. 2 is simple, carry out follow-up cooling and heating steps, obtain the interior band minimum temperature Tm of stove and be 〉=880 ℃, heating rate is 8 ℃/s, and top temperature is 1050 ℃, and soaking time is 12s.In the downstream of stove, rate of cooling from 50 ℃/s to 700-680 ℃/s, the cooling of 5s natural air ,≤400 ℃ of pressurized air coolings (40-80 ℃/s).
Twine 400-380 ℃ temperature.
Produced a kind of mixing ferrite/bainite tissue with remaining austenite district.The remaining austenite percent by volume that records through X-ray diffraction is 12%.The mechanical property that this tissue gives is listed in table 7.
The steel C band of table 7 final thickness 2.2mm
Microstructure characteristic and mechanical property
| Austenite (%) | Rp0.2 (MPa) | Rm (MPa) | Rs/Rm (-) | A (％) |
| 12 | 570 | 980 | 0.57 | 24 |
Yield value (the Rp that raises
0.2) and strength at break always have low yield value/strength at break ratio simultaneously, good ductility (＞22% elongation) and high especially (＞elongation 16000MPa%) and the product of strength at break (A * Rm).
The favorable tissue homogeneity that obtains by the online recrystallize of the thick band of continuous casting, and the existence of remaining austenite gives its finished product these characteristics.
Claims (15)
1. a manufacturing has the method for the carbon steel and low alloy steel band of high checking microstructure, comprises the following steps: successively
The cast thickness scope is the band of 1-6mm in a kind of double-roller continuous casting machine (A), presses mass percent, and its composition is 0.02-0.20C, 0.1-1.6Mn, 0.02-2.00Si,＜0.05Al,＜0.03S,＜0.1P, 0.01-1.5Cr, 0.01-0.5Ni,＜0.5Mo, 0.003-0.012N all the other are Fe and unavoidable impurities;
This band of section controlled chilling between a casting roll and a rolling system (E);
Arrive (Ar at 1150 ℃
1-100) ℃ temperature range is carried out thermal distortion by the rolling system (E) to cast strip, is 15-80% until reduction in thickness, and above-mentioned thermal distortion is selected from following one group of technology:
-＞Ar
3Temperature and a complete austenite phase region rolling, Ar
3Be to cool off austenite phase transformation continuously to begin temperature;
-＜Ar
1Temperature and a complete ferrite phase region rolling;
-at Ar
3To Ar
1Temperature range, and austenite mutually and the ferritic phase coexisting state rolling;
In the outlet of rolling system (E) and the adiabatic system (F) between heating system (G) inlet, under a controlled temperature, band is incubated;
At 670-1150 ℃ of temperature range heating band, the time is 5-40s with said heating system (G), therefore, obtains＞the band recrystallize of 95% volume;
Export and have a plurality of coilers (N, the section between winding system P) carries out controlled chilling to the gained band in said heating system (G).
2. according to the method for the described manufacturing carbon steel and low alloy steel of claim 1 band, it is characterized in that above-mentioned steel band also contains in described casting step:＜0.03Ti,＜0.10V,＜0.035Nb and＜0.005B.
3. according to the method for claim 1 or 2 described manufacturing carbon steel and low alloy steel bands, it is characterized in that by means of individual drive, each section variable, can make the band rate of cooling reach a pair of system (B and D) of the module of 200 ℃/s, section reaching between casting roll and the pinch roll (C) between pinch roll (C) and the rolling system (E) produces above-mentioned controlled chilling.
4. according to the method for the described manufacturing carbon steel and low alloy steel of claim 3 band, it is characterized in that using the type of cooling of selecting from following one group of cooling scheme to realize above-mentioned cooling: natural air, forced ventilation is sprayed rare gas element, air-water, water or its combination in inert chamber.
5. according to the method for the described manufacturing carbon steel and low alloy steel of claim 1 band, it is characterized in that said heating system (G) is in reduction or nonoxidizing atmosphere work.
6. according to the method for the described manufacturing carbon steel and low alloy steel of claim 5 band, it is characterized in that, said heating system (G) is in the temperature work of selecting from following one group of temperature range: corresponding to the temperature that only has the austenite phase, corresponding to the temperature that only has ferritic phase, the temperature that coexists mutually corresponding to ferrite and austenite.
7. according to the method for the described manufacturing carbon steel and low alloy steel of claim 6 band, it is characterized in that, there is the system (H) of a cleaning strip surface said heating system (G) back, is used for from oxide compound or the oxide residue of its surface removing by furnace atmosphere part or Restore All.
8. according to the method for the described manufacturing carbon steel and low alloy steel of claim 1 band, it is characterized in that, by a system (F) that is made of the adiabatic air channel of contain air or rare gas element or its combination, band is incubated under a controlled temperature in rolling system (E) outlet.
9. according to the method for the described manufacturing carbon steel and low alloy steel of claim 1 band, it is characterized in that, outlet at heating system (G), band is subjected to being positioned at three cooling module (I of rolling passage at least, L, M) cooling, these cooling modules can be implemented in each independent section rate of cooling variable, band, and variation range is from the supper-fast adiabatic cooling that is cooled to 0.01 ℃/s of 800 ℃/s.
10. according to the method for the described manufacturing carbon steel and low alloy steel of claim 9 band, it is characterized in that in of above-mentioned cooling module, can electroplating to band.
11. according to the method for the described manufacturing carbon steel and low alloy steel of claim 1 band, it is characterized in that making cast strip produce thermal distortion by two successive milling train seats, each can make band that the reduction in thickness of 15-40% is arranged.
12. according to the method for the described manufacturing carbon steel and low alloy steel of claim 11 band, it is short to it is characterized in that time ratio between the passage between the continuous-rolling seat reaches the recrystallize required time of 50% volume.
13. according to the method for the described manufacturing carbon steel and low alloy steel of claim 3 band, it is characterized in that being provided with a heating system (R), be used for the section heating band between pinch roll (C) and rolling system (E).
14. the method according to the described manufacturing carbon steel and low alloy steel of claim 13 band is characterized in that, said heating system (R) is positioned at the downstream of controlled chilling system (D).
15. the method according to the described manufacturing carbon steel and low alloy steel of claim 1 band is characterized in that, band is at 150-900 ℃ temperature range spooling.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| IT2001RM000678A ITRM20010678A1 (en) | 2001-11-15 | 2001-11-15 | PROCEDURE FOR THE ONLINE RECRYSTALLIZATION OF RAW SOLIDIFICATION TAPES IN CARBON STEEL AND IN ALLOY AND BONDED STEEL |
| ITRM2001A000678 | 2001-11-15 |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN1606629A CN1606629A (en) | 2005-04-13 |
| CN1296498C true CN1296498C (en) | 2007-01-24 |
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ID=11455880
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CNB02825466XA Expired - Fee Related CN1296498C (en) | 2001-11-15 | 2002-11-15 | In-line process for the recrystallization of solidified coarse strips in carbon steel and in low-alloyed steel and so obtainable strips having a highly checked microstructure |
Country Status (6)
| Country | Link |
|---|---|
| EP (1) | EP1444371B1 (en) |
| CN (1) | CN1296498C (en) |
| AT (1) | ATE293174T1 (en) |
| DE (1) | DE60203733T2 (en) |
| IT (1) | ITRM20010678A1 (en) |
| WO (1) | WO2003062476A1 (en) |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE102005063058B3 (en) * | 2005-12-29 | 2007-05-24 | Thyssenkrupp Nirosta Gmbh | Producing cold rolled strip of ferritic stainless steel comprises controlled cooling before cold rolling |
| CN103305759B (en) * | 2012-03-14 | 2014-10-29 | 宝山钢铁股份有限公司 | Thin strip continuous casting 700MPa grade high-strength weather-resistant steel manufacturing method |
| CN103305770B (en) * | 2012-03-14 | 2015-12-09 | 宝山钢铁股份有限公司 | A kind of manufacture method of thin strap continuous casting 550MPa level high-strength air corrosion-resistant steel band |
| CN103302255B (en) * | 2012-03-14 | 2015-10-28 | 宝山钢铁股份有限公司 | A kind of thin strap continuous casting 700MPa level high-strength air corrosion-resistant steel manufacture method |
| CN103305754B (en) * | 2012-03-14 | 2015-09-23 | 宝山钢铁股份有限公司 | A kind of age hardening thin strap continuous casting low-carbon microalloy steel band manufacture method |
| EP2821520B1 (en) * | 2013-07-03 | 2020-11-11 | ThyssenKrupp Steel Europe AG | Method for the coating of steel flat products with a metallic protective layer |
| JP6452037B2 (en) * | 2014-02-04 | 2019-01-16 | 日立金属株式会社 | Casting method and casting apparatus |
| EP3754033B1 (en) | 2014-12-16 | 2022-08-24 | Greer Steel Company | Method of forming rimfire ammunition cartridge |
| CN112517863A (en) * | 2019-09-19 | 2021-03-19 | 宝山钢铁股份有限公司 | High-strength thin-specification patterned steel plate/belt and manufacturing method thereof |
| CN114669613B (en) * | 2022-04-19 | 2023-06-20 | 安徽工业大学 | Flexible roller contact type Bao Daizu cooling method |
Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0707908A1 (en) * | 1994-04-04 | 1996-04-24 | Nippon Steel Corporation | Twin-roll type continuous casting method and device |
| EP0776984A1 (en) * | 1995-05-08 | 1997-06-04 | Nippon Steel Corporation | Equipment for continuously manufacturing metal coils and metal coil manufacturing method |
| EP0818545A1 (en) * | 1996-01-26 | 1998-01-14 | Nippon Steel Corporation | Process for continuously casting sheet metal and apparatus for continuously producing sheet metal |
| CN1306582A (en) * | 1997-12-19 | 2001-08-01 | 埃克森美孚上游研究公司 | Ultra-high strength dual phase steels with excellent cryogenic temperature toughness |
-
2001
- 2001-11-15 IT IT2001RM000678A patent/ITRM20010678A1/en unknown
-
2002
- 2002-11-15 DE DE60203733T patent/DE60203733T2/en not_active Expired - Fee Related
- 2002-11-15 AT AT02793320T patent/ATE293174T1/en not_active IP Right Cessation
- 2002-11-15 WO PCT/IT2002/000728 patent/WO2003062476A1/en not_active Application Discontinuation
- 2002-11-15 EP EP02793320A patent/EP1444371B1/en not_active Expired - Lifetime
- 2002-11-15 CN CNB02825466XA patent/CN1296498C/en not_active Expired - Fee Related
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0707908A1 (en) * | 1994-04-04 | 1996-04-24 | Nippon Steel Corporation | Twin-roll type continuous casting method and device |
| EP0776984A1 (en) * | 1995-05-08 | 1997-06-04 | Nippon Steel Corporation | Equipment for continuously manufacturing metal coils and metal coil manufacturing method |
| EP0818545A1 (en) * | 1996-01-26 | 1998-01-14 | Nippon Steel Corporation | Process for continuously casting sheet metal and apparatus for continuously producing sheet metal |
| CN1306582A (en) * | 1997-12-19 | 2001-08-01 | 埃克森美孚上游研究公司 | Ultra-high strength dual phase steels with excellent cryogenic temperature toughness |
Also Published As
| Publication number | Publication date |
|---|---|
| DE60203733D1 (en) | 2005-05-19 |
| ITRM20010678A1 (en) | 2003-05-15 |
| DE60203733T2 (en) | 2006-02-09 |
| ITRM20010678A0 (en) | 2001-11-15 |
| ATE293174T1 (en) | 2005-04-15 |
| EP1444371A1 (en) | 2004-08-11 |
| EP1444371B1 (en) | 2005-04-13 |
| CN1606629A (en) | 2005-04-13 |
| WO2003062476A1 (en) | 2003-07-31 |
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