CN100381598C - Orientating silicon steel, manufacturing process and equipment - Google Patents
Orientating silicon steel, manufacturing process and equipment Download PDFInfo
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- CN100381598C CN100381598C CNB2004100990807A CN200410099080A CN100381598C CN 100381598 C CN100381598 C CN 100381598C CN B2004100990807 A CNB2004100990807 A CN B2004100990807A CN 200410099080 A CN200410099080 A CN 200410099080A CN 100381598 C CN100381598 C CN 100381598C
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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
- C21D8/12—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of articles with special electromagnetic properties
- C21D8/1244—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of articles with special electromagnetic properties the heat treatment(s) being of interest
- C21D8/1255—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of articles with special electromagnetic properties the heat treatment(s) being of interest with diffusion of elements, e.g. decarburising, nitriding
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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
- C21D8/12—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of articles with special electromagnetic properties
- C21D8/1277—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of articles with special electromagnetic properties involving a particular surface treatment
- C21D8/1283—Application of a separating or insulating coating
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Abstract
The present invention relates to oriented silicon steel as well as a manufacture method and a manufacture device of the oriented silicon steel. The oriented silicon steel comprises the following components: 0.035 to 0.060 wt% of C, 2.5 to 3.5 wt% of Si, 0.08 to 1.8 wt% of Mn, 0.005 to 0.010 wt% of S, 0.015 to 0.035 wt% of Als, 0.0050 to 0.0090 wt% of N, 0.01 to 0.15 wt% of Sn, 0.010 to 0.030 wt% of P, 0.05 to 0.12 wt% of Cu, and the rest is Fe. The manufacture method comprises: a. smelting; b. hot rolling, casting blanks are heated to the temperature of 1100 to 1200 DEG C, a rolling temperature is lower than 1200 DEG C, a finishing temperature is above 850 DEG C, and a winding temperature is below 650 DEG C; c. normalizing, the normalizing annealing at the temperature of 1050 to 1180 DEG C (1 to 20 seconds) and at the temperature of 850 to 950 DEG C (30 to 200 seconds) of hot rolled plates are carried out, and the hot rolled plates are rapidly cooled; d. cold rolling, the cooled hot rolled plates are rolled to the thickness of finished plates by a primary cold rolling method or a repetitious cold rolling method with intermediate annealing; e. nitriding and decarbonization, high temperature annealing isolating agents which contain main components of MgO are coated; the high temperature annealing and the hot levelling annealing are carried out.
Description
Technical field
The present invention relates to a kind of oriented silicon steel and production method thereof, be characterized in obtaining the required inhibitor of secondary recrystallization by steel plate nitriding (Nitriding), form perfect Goss tissue during final high temperature annealing, and form Watch glass matter film, obtain oriented silicon steel finished product with tradition directed silicon steel homomorphosis.
Background technology
The production method of oriented silicon steel (Grain oriented silicon steel) is as follows traditionally:
Make steel with converter (or electric furnace), carry out secondary refining and alloying, continuous casting becomes slab, its basic chemical ingredients is Si (2.5~4.5%), [C] (0.01~0.10%), Mn (0.03~0.1%), S (0.012~0.050%), Als (0.01~0.05%), N (30~120ppm), the composition system that has also contains one or more in the elements such as Cu, Mo, Sb, Cr, B, Bi, and all the other are iron and unavoidable impurities element; The temperature of slab about special-purpose high temperature process furnace internal heating to 1400 ℃, and carry out insulation more than 30 minutes, make the abundant solid solution of inclusion, so that in course of hot rolling subsequently, in the silicon steel matrix, separate out second phase particle, the i.e. inhibitor tiny, disperse; After the hot-rolled sheet normalizing (or not normalizing), carry out pickling, remove scale on surface; With once cold rolling or comprise that twice above cold rolling process of process annealing rolls finished product thickness, carry out decarburizing annealing and coating is the annealing separating agent of main component with MgO, [C] in the steel plate taken off the degree that do not influence finished product magnetic (generally should below 30ppm); In the high-temperature annealing process, steel plate generation secondary recrystallization, Mg2SiO4 bottom form and purify physicochemical change such as (remove in the steel S, N etc. to the deleterious element of magnetic), obtain orientation degree height, oriented silicon steel that iron loss is low; At last, through the coating insulating coating and the annealing that stretches, obtain the oriented silicon steel of commercial applications form.
The distinguishing feature of tradition directed silicon steel has:
(1) inhibitor just forms from the steel-making beginning, and in each operation thereafter, inhibitor all plays a role, and must control and adjust it;
(2) slab heat, Heating temperature are the Limiting Level of traditional heating stove up to 1420 ℃, and the control of rolling line temperature drop also is the limit of existing hot rolling technology;
(3) key of production technology is tissue, the texture of each stage steel plate of control, and the behavior of inhibitor;
(4) owing to heat, scaling loss is big, process furnace needs frequent the repairing, and utilization ratio is low, simultaneously, and the energy consumption height; The limit of hot rolled coil is split greatly, causes cold rolling process to produce difficulty, and lumber recovery is low, the cost height.
High temperature oriented silicon steel production technology is through the development of over half a century, very ripe, for the power electronics industrial expansion has been made contribution, produced top oriented silicon steel, but owing to the blockade on new techniques between its complex manufacturing, with high content of technology, enterprise seriously reaches reasons such as the specificity of product and aggregate demand be less, the steelmaker of grasping this technology is less; On the other hand, because heat, a series of problems have appearred, as the special-purpose high temperature process furnace must be arranged, productivity is poor, cost is high.In order to address these problems, in long-term production practice and research work, people have groped and have developed some successful ways, now are summarized as follows:
(1) electromagnetic-induction heating method
Nippon Steel and Kawasaki all have electromagnetic induction heating technology, and on essence, this method still belongs to high temperature slab heating means, in the heat stage that different is at slab, in electromagnetic induction heating furnace, feed N
2, H
2Two kinds of shielding gas, accurately controlled atmosphere, the high temperature oxidation of minimizing steel billet simultaneously, because rate of heating is fast, reduces the high temperature time inside furnace.This method has solved the limit preferably and has split problem, the limit can be split to reduce to below the 15mm, has improved the productivity of oriented silicon steel, splits but can not eliminate the limit fully.
(2) warm oriented silicon steel production method in
Warm oriented silicon steel production technology during factories such as Muscovite VIZ adopt, 1250~1300 ℃ of slab heating temperatures contain higher Cu in the chemical ingredients, be inhibitor with AlN and Cu.The inhibitor and the pyroprocess of this method are similar, also are a kind of geneogenous inhibitor.Problem is split on the limit that can avoid heat to bring fully, but shortcoming is to produce general oriented silicon steel, can not produce high magnetic induction grain-oriented silicon steel.
(3) Ri Ben low temperature slab heating means
Slab is in heating below 1250 ℃, and hot-rolled sheet is boundless to be split, and productivity is good.The nitriding of inhibitor after by decarburizing annealing obtains, and is a kind of posteriori acquisition type inhibitor, both can produce general oriented silicon steel, can produce high magnetic induction oriented silicon steel again.
(4) CSP produces the oriented silicon steel method
Problem is split on the hot rolling limit that this method has also solved oriented silicon steel, has improved productivity, has reduced production cost.Inhibitor also can be an acquisition day after tomorrow type, obtains by nitriding.
Obviously, low temperature slab heating technique has thoroughly solved the inherent defect of high temperature slab heating technique, has improved productivity, has reduced cost, has represented the direction of technical development.
The disclosed method of low-temperature oriented silicon steel technology such as Japanese Patent [flat 3-211232], its chemical ingredients 1 is: [C] 0.025%~0.075%, Si 2.5%~4.5%, S≤0.015%, Als 0.010~0.050%, N≤0.0010~0.0120%, Mn 0.05~0.45%, and all the other are Fe and inevitable inclusion Sn 0.01~0.10%.Slab is carrying out hot rolling after the heating below 1200 ℃, cold rolling or have the above cold rolling process of twice of process annealing to be rolled down to final product thickness with 1 time, cold rolling draft is more than 80%, then carry out decarburizing annealing and high temperature annealing, in the secondary recrystallization initial stage nitriding of decarburizing annealing and high temperature annealing.
Japanese patent laid-open 5-112827, chemical ingredients: [C] 0.025%~0.075%, Si2.5%~4.5%, S≤0.012%, Als 0.010~0.060%, N≤0.010%, Mn 0.08~0.45%, and P 0.015~0.045%, and all the other are Fe and inevitable inclusion.Slab carries out hot rolling after heating below 1200 ℃.With 1 time cold rolling or have the above cold rolling process of twice of process annealing to be rolled down to final product thickness, steel plate carries out continuous nitriding after the decarburizing annealing in traveling process, carries out high temperature annealing behind the separant coating, all good oriented silicon steels of production magnetic and bottom layer quality.
Continuous nitriding method: protective atmosphere is H
2And N
2Mixed gas, NH wherein
3Content is more than the 1000ppm, and the oxygen gesture is PH
2O/PH
2≤ 0.04, nitriding temperature is 500~900 ℃; During high temperature annealing, in 600~850 ℃ temperature range, keep weak oxide atmosphere.
Also just like the low temperature technique of Acciai Speciali Terni S.P. A., Chinese patent CN-1228817A, chemical ingredients: Si 2.5~5%, C 0.002~0.075%, and Mn 0.05~0.4%, S (or S+0.503Se)<0.015%, the solvable Al 0.010~0.045% of acid, N 0.003~0.013%, Sn≤0.2%, and all the other are Fe and unavoidable impurities.The steel of mentioned component is cast into thin slab, in the heating of 1150~1300 ℃ temperature, after the hot rolling, carry out normalizing annealing and draft greater than 80% finally cold rolling, during final high temperature annealing, the control annealing atmosphere, the amount of nitrogen sucking that makes steel is less than 50ppm.This method mainly is suitable for sheet blank continuous casting and produces oriented silicon steel; But it does not adopt nitridation process.
Chinese patent CN-1231703A, the chemical ingredients system belongs to low-carbon (LC) and copper bearing composition system, and production method is basically identical also, and different is after decarburizing annealing steel plate to be carried out nitriding, and nitriding temperature is 900~1050 ℃, the nitriding amount is lower than 50ppm.Be suitable for thin slab and produce oriented silicon steel.
Chinese patent CN-1242057A, chemical ingredients: Si 2.5~4.5%; C 150~750ppm, best 250~500ppm; Mn 300~4000ppm, best 500~2000ppm; S<120ppm, best 50~70ppm; The solvable Al 100~400ppm of acid, best 200~350ppm; N 30~130ppm, best 60~100ppm; Ti<50ppm is preferably less than 30ppm; All the other are Fe and unavoidable impurities.1200~1320 ℃ of slab heating temperatures, 850~1050 ℃ of nitriding temperatures.All the other technologies and top two basic identical.
The low temperature technique that Posco Posco is arranged again, its low-temperature oriented silicon steel chemical ingredients is: C0.02~0.045%, Si 2.9~3.30%, and Mn 0.05~0.3%, sour solvable Al 0.005~0.019%, N0.003~0.008%, S<0.006%, Cu 0.30~0.70%, and Ni 0.30~0.70%, Cr 0.30~0.70%, and all the other are Fe and unavoidable impurities.In addition, contain B 0.001~0.012% in the steel; Decarburization and nitriding are carried out simultaneously, nitriding in wet atmosphere.The basis of this method is to be main inhibitor with BN.
By to both at home and abroad based on the producing oriented silicon steel by heating low temperature casting blank technical Analysis of nitridation process, can find: the technology of Japan concentrates on after the decarburizing annealing in the secondary recrystallization process, to the steel plate nitriding, nitriding temperature is low, and inhibitor formed in the early stage of high temperature annealing; The technology in Europe is to carry out nitriding after the decarburizing annealing, and perhaps decarburizing annealing and nitriding are carried out simultaneously, the nitriding temperature height; The technology of Posco Posco is applicable to that its low-carbon (LC) hangs down the high Cu of Al, Ni, Cr alloying constituent system, and nitriding and decarburization are carried out simultaneously.
When producing oriented silicon steel with the nitridation process of Japan, owing to do not have inhibitor in the steel plate, can not suppress growing up of primary recrystallization crystal grain, the primary recrystallization grain-size is mainly controlled by temperature and time, thereby the control of decarburizing annealing and nitridation process requirement is high, and process window is narrow; On the other hand, because nitriding is carried out after decarburizing annealing, surface of steel plate has formed one deck with SiO
2Be the zone of oxidation of main component, the homogeneity of nitriding and nitriding behavior are subject to the influence of surface oxide layer.Acciai Speciali Terni S.P. A.'s technical characterstic is the high temperature nitriding, in order to realize this technology, and the second phase particle that must have disperse to separate out in the hot-rolled sheet, the Heating temperature of slab is higher, as about 1250 ℃, thereby will control favourable being mingled with in the hot-rolled sheet.In addition, its nitriding is carried out after decarburization or with decarburizing annealing simultaneously, and nitriding also can be subjected to the influence of surface of steel plate zone of oxidation.Posco also is a technology mode of taking decarburization, nitriding to carry out simultaneously, and the surface of steel plate zone of oxidation is inevitable to the influence of nitriding; In addition, the Al content in the steel is low, is main inhibitor with BN, and the unstable of B will cause the instability of the ability that suppresses, and the stability of magnetic can be subjected to very big influence.
The chemical ingredients system of several low temperature slab heating technique oriented silicon steels is more as shown in table 1.
Table 1 chemical ingredients system comparative unit wt.%
C | Si | Mn | P | S | N | Als | Cu | Sn | B | Ni | Cr | |
Japan | 0.025 ~ 0.075 | 2.5 ~ 4.5 | 0.05 ~ 0.45 | 0.015 ~ 0.045 | ≤ 0.015 | 0.0010 ~ 0.0120 | 0.010 ~ 0.050 | / | 0.01 ~ 0.10 | 0.0005 ~ 0.0080 | / | / |
AST | 0.002 ~ 0.075 | 2.5 ~ 5 | 0.05 ~ 0.4 | / | ≤ 0.015 | 0.003 ~ 0.013 | 0.010 ~ 0.045 | / | ≤ 0.2 | / | / | / |
Posco | 0.02 ~ 0.045 | 2.9 ~ 3.30 | 0.05 ~ 0.3 | / | < 0.006 | 0.003 ~ 0.008 | 0.005 ~ 0.019 | 0.30 ~ 0.70 | / | 0.001 ~ 0.012 | 0.30 ~ 0.70 | 0.30 ~ 0.70 |
As previously mentioned, high temperature slab heating means are produced oriented silicon steel and are had inherent defects such as energy consumption height, the process furnace service efficiency is low, measure on edge crack of hot rolled plate is big, productivity is bad, cost is low, low temperature slab heating technique is produced oriented silicon steel and can be addressed these problems preferably, thereby has powerful exploitation power.At present disclosed low temperature slab heating technique is produced oriented silicon steel in the patent documentation, nearly all is to be based upon on the basis of nitridation process, and the nitridation process technology is to realize the key of low temperature slab heating.In the existing nitriding method, the influence that nitriding amount in the steel plate and homogeneity are subjected to surface oxide layer, thus magnetic is exerted an influence.
Adopt the mode of slab heat to produce oriented silicon steel, slab heating temperature is up to 1400 ℃, make the favourable abundant solid solution that is mingled with, and after heating, carry out high temperature rolling, obtaining favourable inclusion distributes and size, when high temperature annealing, suppress primary recrystallization crystal grain, obtain good secondary recrystallization tissue.The shortcoming of this production method is:
(1) necessary special-purpose high-temperature heater;
(2) owing to heat, the steel slab surface slag is serious, causes process furnace frequently to repair, the maintenance cost height, and the operating rate of stove is low;
(3) thickness of slab is generally 200~250mm, for homogeneous heating, and necessary long-time heating, energy consumption height;
(4) the column crystal prosperity in the slab, grain boundary oxidation causes the limit to be split seriously, and back operation productivity is poor, and lumber recovery is low, the production cost height.
Summary of the invention
The object of the present invention is to provide a kind of oriented silicon steel and production method thereof, before decarburizing annealing steel plate is carried out nitriding and handle, surface of steel plate does not have zone of oxidation, has overcome the defective of other similar approach; On the other hand, in decarburizing annealing, nitrogen in the steel plate further spreads, and form (Al, Si) N is favourable and be mingled with, utilize its restraining effect to primary recrystallization crystal grain, can control the primary recrystallization tissue of steel plate effectively, to obtain to stablize, perfect secondary recrystallization finished product organizes highly beneficial.Making method of the present invention compare with other method has an enormous advantage.
For achieving the above object, technical scheme of the present invention is, a kind of oriented silicon steel, and its component (weight percent) is:
C 0.035~0.060%
Si 2.5~3.5%
Mn 0.08~1.8%
S 0.005~0.010%
Als 0.015~0.035%
N 0.0050~0.0090%
Sn 0.01~0.15%
P 0.010~0.030%
Cu 0.05~0.12%
All the other are Fe and inevitable inclusion.
The production method of oriented silicon steel of the present invention comprises the steps,
A. smelt, with converter or Electric furnace steel making, the molten steel of mentioned component obtains strand behind secondary refining and continuous casting;
B. hot rolling, strand are heated to 1100~1200 ℃, and start rolling temperature is less than 1200 ℃, and finishing temperature is more than 850 ℃, and coiling temperature is below 650 ℃;
C. normalizing is handled, and hot-rolled sheet carries out the normalizing annealing of 1050~1180 ℃ (1~20 seconds) and 850~950 ℃ (30~200 seconds), and cools off fast, and speed of cooling is greater than 25 ℃/s;
D. cold rolling, use once or be with the above cold rolling process of secondary of process annealing to roll production board thickness, its final draft must surpass 80%;
E. nitriding, decarburization are carried out nitriding processing and decarburizing annealing to the steel plate that rolls finished product thickness, and coating is the high temperature annealing separant of main component with MgO;
F. high temperature annealing and hot-leveling annealing, high temperature annealing routinely and hot-leveling technology are carried out.Wherein, described nitridation process comprises,
Heating zone dew point: below-20 ℃;
Nitriding temperature: 750~900 ℃;
Nitriding time: 5~50 seconds;
Nitriding medium: NH
3, require to use dried NH
3, dew point is below-20 ℃;
Protective atmosphere: H
2With N
2Mixed gas, H
2Content: 20~75%, below the atmosphere dew point-20 ℃, NH
3Concentration: 0.1~15%;
Nitriding amount: 50~200ppm, the purpose of nitriding is to form favourable being mingled with, by nitriding method of the present invention, after nitriding is finished, in the steel plate carbon rejection process, the nitrogen that infiltrates surface of steel plate will spread, and formation is mingled with based on (Al, Si) the favourable of N, to the restraining effect of having grown up of a crystal grain, be convenient to carry out the adjustment of grain structure.
Complex function annealing furnace of the present invention, its body of heater comprises heating zone, nitriding section, decarbonization section and reduction section, it is characterized in that, three atmosphere disrupters are set between described heating zone, nitriding section, decarbonization section and the reduction section, make things convenient for the atmosphere control of each stove section, make it can not influence each other.
Wherein, described atmosphere disrupter is a diaphragm structure.
Described heating zone is radiator tube heating or electromagnetic induction heating, fast steel band is heated to nitriding temperature.
Described nitriding section, decarbonization section and reduction section adopt Electric heating.
Decarbonization section had both play a part the steel plate decarburization is also played the N diffusion, formed (Al, Si) N inhibitor.
A) smelt
It is generally acknowledged that producing oriented silicon steel with nitriding process needs S is controlled at below 0.007%.But the present invention finds, when S<0.005%, can influence secondary recrystallization and magnetic property on the contrary, and this may be that AlN is with (Cu) there is certain phase relation in Mn: (2110) between the S
AlN// (110)
(Mn, Cu) SRelevant, S too high levels or the low excessively form of separating out that all can influence AlN.For this reason, among the present invention S content is controlled between 0.005%~0.010%.
Add Cu can separate out micro-small and dispersed (Cu, Mn)
xS or Cu
xThe S particle, restraint strengthens, and improves finished product magnetic.Add (110)<001 after Cu can also improve hot-rolled sheet and decarburizing annealing〉position is to crystal grain, reduces (100)<001〉position is to crystal grain, promotes secondary recrystallization.But the rapid alligatoring when 0.12% can make precipitate in normalizing when above of Cu content, thus influence AlN separate out form and distribution.Therefore, among the present invention Cu content is controlled between 0.05%~0.12%.
The present invention is owing to adopt traditional casting process, and therefore the oriented steel production technique with the employing CSP of announcements such as patent CN-1228817A, US6273964B1, US6296719B1 has bigger difference.
B) hot rolling
Strand is in process furnace internal heating to 1100~1200 ℃, and less than 1200 ℃ of open rollings, the temperature finish to gauge more than 850 ℃ rolls into the hot-rolled sheet of 1.5~3.5mm thickness, and coiling temperature is below 650 ℃.
The Heating temperature of slab is mainly determined that by following two factors the first is in order to ensure hot worked stability, and the general requirement Heating temperature is higher, and this has constituted lowest temperature; It two is in order to prevent the deterioration of magnetic property, requires Heating temperature low, and this has just constituted upper temperature limit.In traditional oriented steel production technique, for in the annealing process of hot rolling or hot-rolled sheet, forming inhibitor such as tiny, uniform MnS, AlN, must earlier strand be heated to 1350~1400 ℃ and make MnS thick in the strand, the solid solution of AlN precipitate, be a kind of slab heat technology therefore.
Serious problems such as split for overcoming oxidation, limit that the heat technology brings, existing employing nitriding forms directional silicon steel slab low-temperature heat technology such as acquired inhibitor (Low temperature slabreheating), mainly contain following a few class: the one, in the high temperature annealing separant, add the nitriding chemical ingredients, make the steel band nitriding form (Al in the high temperature annealing stage then, Si) inhibitor such as N is as the flat 1-230721 of special permission communique, flat 1-283324 etc.; Another kind of is to utilize the nitriding atmosphere of high temperature annealing temperature rise period to carry out nitriding.This two class is all inhomogeneous etc. former thereby fail to obtain the product of magnetic stability because of nitriding.On this basis, another technology that occurs is to feed active stronger ammonia after process annealing, decarburizing annealing or in decarburizing annealing in atmosphere, the technology that is disclosed as the flat 2-182866 of Japan's special permission communique, flat 2-228425, flat 2-294428, flat 3-2324, WO9902742 etc.Patent US6273964B1 and US6296719B1 have disclosed the oriented steel production technique that adopts CSP, because the speed of cooling of strand is very fast, can significantly reduce the mean sizes of precipitate in the strand, therefore in process furnace subsequently, as long as can make the inhibitor solid solution to thin slab implementation lesser temps (1150 ℃~1300 ℃) and the heating of short period (10~20 minutes), so also can realize the slab low-temperature heat; As be aided with the nitriding of decarbonization process, can obtain high magnetic strength product.
C) normalizing
Hot-rolled sheet carries out the normalizing annealing of 1050~1180 ℃ (1~20 seconds)+(850~950 ℃ * 30~200 seconds), and cools off fast, and speed of cooling is greater than 25 ℃/s.
D) cold rolling
With once or the above cold-rolling practice of secondary of band process annealing roll production board thickness, but final draft must surpass 80%.
E) nitriding, decarburization
The steel plate that rolls finished product thickness is carried out nitriding processing and decarburizing annealing (Decarburizationannealing), and coating is the high temperature annealing separant of main component with MgO.Nitridation technique as gordian technique of the present invention is described as follows:
The described nitriding process of US6296719B1 is after decarburizing annealing, and nitriding temperature is 900~1050 ℃, usually more than 1000 ℃.By nitriding, steel band can increase the nitrogen content of 50ppm, thereby forms tiny aluminium nitride precipitated phase, and this process must contain the water vapor of 0.5~100g/m3.And the nitriding process of this patent is before decarburization, and the water-content in the atmosphere is far below 0.5g/m3.
The nitriding method that Japan flat 2-294428, the WO9902742 of special permission communique disclosed all carries out simultaneously with decarburization, main (the Al that in the crystal boundary on steel band top layer, forms, Si) inhibitor such as N, therefore the surface layer grain that makes primary recrystallization is effectively suppressed and very tiny, but inner crystal grain is very thick, and the result makes secondary recrystallization become unstable; And, increased difficulty and complicacy owing to must control decarburization and nitriding process simultaneously, therefore this method also is difficult to obtain the product of magnetic stability.The present invention is owing to carried out nitriding and handle before decarburization, thus decarburization and nitriding process can be separately, controlled effectively, guaranteed the stable control of decarburized amount, nitriding amount, thereby obtained stable magnetic.
The flat 2-182866 of Japan special permission communique discloses is nitriding method after decarburizing annealing, but this method is not owing to have inhibitor in the steel plate, can not suppress growing up of primary recrystallization crystal grain, the primary recrystallization grain-size is mainly controlled by temperature and time, thereby the control of decarburizing annealing and nitridation process requirement is high, and process window is narrow; On the other hand, because nitriding is carried out after decarburizing annealing, surface of steel plate has formed one deck with SiO
2Be the zone of oxidation of main component, the homogeneity of nitriding and nitriding behavior are subject to the influence of surface oxide layer.And therefore the present invention can avoid above-mentioned nitriding process to produce the inherent defect of orientation silicon steel process owing to carry out the nitriding processing prior to decarburization, has obtained good magnetic performance.
Beneficial effect of the present invention
(1) nitriding efficient height, the steel plate nitriding does not have the influence of surface film oxide;
(2) nitriding temperature is higher, and the nitriding in 800~900 ℃ of scopes of experimental result steel plate is best;
(3) the nitrogen diffusion in the steel plate is infiltrated in decarburizing annealing after the nitriding, forms inhibitor;
(4) solved the intrinsic contradictions of high temperature oriented silicon steel production method fully, energy consumption is low, production cost is low, and in addition, owing to do not need special-purpose high temperature bar plate heating stove, the handiness of production improves greatly, does not constitute the production capacity restriction of hot rolls, and potential benefit is big.
Embodiment
Embodiment 1: with the steel-making of 500kg vacuum oven, chemical ingredients and hot-rolled condition are shown in table 2 and table 3.The cooling of 1150 ℃ of normalizing conditions * 5s+930 ℃ * 70s+50 ℃/s, cold rolling of strip steel be to 0.30mm, 850 ℃ of nitridings, and the about 110ppm of nitriding carries out high temperature annealing and smooth annealing after decarburization and the coating MgO separant, is coated with insulation layer, surveys magnetic.Experimental result is as shown in table 4.
Table 2 experimental steel chemical ingredients unit: %
Embodiment | C | Si | Mn | P | S | Al | N | Cu | Sn |
A | 0.055 | 3.20 | 0.13 | 0.020 | 0.0060 | 0.0275 | 0.0070 | 0.065 | 0.08 |
B | 0.049 | 3.26 | 0.15 | 0.017 | 0.0075 | 0.0234 | 0.0085 | 0.061 | 0.03 |
Table 3 experimental steel hot-rolled condition unit ℃
Heating temperature | Finishing temperature | Coiling temperature | Thickness (mm) | |
A | 1170 | 920 | 500 | 2.3 |
B | 1140 | 900 | 520 | 2.3 |
Table 4 experimental result
B8(T) | P1.7/50(w/kg) | |
AA BB | 1.93 1.93 | 0.97 0.99 |
Embodiment 2: carry out the nitriding condition experiment with A hot-rolled condition steel in A composition and the table 3 in the table 2, under 850 ℃ * 10s, dew point is as shown in table 5 to the influence of nitriding amount, and the relation of nitriding amount and magnetic is as shown in table 6.
The relation of table 5 dew point and nitriding amount
The heating zone dew point (℃) | The nitriding dew point (℃) | Nitriding amount (ppm) | |
1 | -25 | -25 | 150 |
2 | -20 | -30 | 145 |
3 | -5 | -10 | 70 |
The relation of table 6 nitriding amount and magnetic
Nitriding amount (ppm) | B8(T) | P1.7/50(w/kg) | |
1 | 90 | 1.91 | 1.00 |
2 | 120 | 1.95 | 0.95 |
3 | 150 | 1.93 | 0.97 |
Other embodiment of the present invention see Table 7:
Table 7 unit: wt%
Embodiment | C | Si | Mn | P | S | Al sol. | N | Cu | Sn | B 8(T) | P 17/50 |
1 | 0.045 | 3.25 | 0.18 | 0.023 | 0.006 | 0.027 | 0.0070 | 0.05 | 0.08 | 1.93 | 0.98 |
2 | 0.035 | 3.20 | 0.16 | 0.020 | 0.005 | 0.028 | 0.0074 | 0.06 | 0.08 | 1.91 | 1.00 |
3 | 0.050 | 3.22 | 0.15 | 0.021 | 0.005 | 0.025 | 0.0081 | 0.07 | 0.04 | 1.95 | 0.95 |
4 | 0.051 | 3.18 | 0.14 | 0.019 | 0.007 | 0.026 | 0.0075 | 0.05 | 0.07 | 1.93 | 0.98 |
5 | 0.047 | 3.15 | 0.13 | 0.018 | 0.008 | 0.024 | 0.0065 | 0.08 | 0.06 | 1.94 | 0.96 |
6 | 0.055 | 3.30 | 0.17 | 0.022 | 0.008 | 0.027 | 0.0068 | 0.07 | 0.09 | 1.93 | 0.96 |
7 | 0.049 | 3.26 | 0.15 | 0.017 | 0.007 | 0.023 | 0.0085 | 0.06 | 0.03 | 1.93 | 0.99 |
8 | 0.055 | 3.15 | 0.13 | 0.015 | 0.007 | 0.019 | 0.0080 | 0.07 | 0.05 | 1.90 | 1.02 |
9 | 0.050 | 3.48 | 0.12 | 0.019 | 0.006 | 0.015 | 0.0072 | 0.08 | 0.10 | 1.94 | 0.95 |
10 | 0.040 | 3.50 | 0.10 | 0.025 | 0.007 | 0.020 | 0.0063 | 0.09 | 0.14 | 1.91 | 1.02 |
11 | 0.043 | 2.50 | 0.11 | 0.030 | 0.009 | 0.021 | 0.0052 | 0.09 | 0.01 | 1.90 | 1.03 |
12 | 0.060 | 3.05 | 0.12 | 0.011 | 0.005 | 0.031 | 0.0070 | 0.09 | 0.12 | 1.92 | 0.99 |
13 | 0.053 | 3.10 | 0.08 | 0.025 | 0.008 | 0.035 | 0.0091 | 0.10 | 0.08 | 1.92 | 1.00 |
14 | 0.045 | 2.95 | 0.15 | 0.012 | 0.007 | 0.017 | 0.0083 | 0.12 | 0.09 | 1.91 | 1.01 |
15 | 0.052 | 3.15 | 0.17 | 0.022 | 0.008 | 0.026 | 0.0075 | 0.07 | 0.06 | 1.94 | 0.97 |
16 | 0.055 | 3.20 | 0.13 | 0.020 | 0.006 | 0.028 | 0.0070 | 0.07 | 0.15 | 1.93 | 0.97 |
Comparative example | 0.051 | 3.10 | 0.15 | / | 0.007 | 0.021 | 0.0080 | / | / | 1.88 | 1.15 |
Annotate: comparative example is the data among the CN1242057A
Method of the present invention has solved the problem that prior art exists effectively, and compare with the similar approach of Japan, Posco and Acciai Speciali Terni S.P. A., method of the present invention, before decarburizing annealing steel plate being carried out nitriding handles, surface of steel plate does not have zone of oxidation, has overcome the defective of other similar approach; On the other hand, in decarburizing annealing, the nitrogen diffusion in the steel plate, and form (Al, Si) N is favourable and be mingled with, utilize its restraining effect, can control the primary recrystallization tissue of steel plate effectively primary recrystallization crystal grain, to obtain to stablize, perfect secondary recrystallization finished product organizes highly beneficial.Making method of the present invention compare with other method has an enormous advantage.
Low temperature slab heating technique is produced the cutting edge technology that oriented silicon steel has been represented the oriented silicon steel development, the enforcement of the inventive method is except nitriding decarburization stove needs particular design, all the other equipment are the conventional equipment of producing oriented silicon steel, and conventional decarburization annealing furnace can be transformed into nitriding decarburization stove, the realization technology is simple, thereby has good popularizing application prospect.
Claims (8)
1. oriented silicon steel, the weight percent of its component is:
C 0.035~0.060%
Si 2.5~3.5%
Mn 0.08~1.8%
S 0.005~0.010%
Als 0.015~0.035%
N 0.0050~0.0090%
Sn 0.01~0.15%
P 0.010~0.030%
Cu 0.05~0.12%
All the other are Fe and inevitable inclusion;
Described oriented silicon steel, by following method manufacturing:
A. smelt, with converter or Electric furnace steel making, molten steel obtains strand behind secondary refining and continuous casting;
B. hot rolling, strand are heated to 1100~1200 ℃, and start rolling temperature is less than 1200 ℃, and finishing temperature is more than 850 ℃, and coiling temperature is below 650 ℃;
C. normalizing is handled, and hot-rolled sheet carries out 1050~1180 ℃ of 1~20 second and 850~950 ℃ of normalizing annealings of 30~200 seconds down down, and cools off fast, and speed of cooling is greater than 25 ℃/s;
D. cold rolling, use once or be with the above cold rolling process of secondary of process annealing to roll production board thickness, its final draft must surpass 80%;
E. nitriding, decarburization are carried out nitriding processing and decarburizing annealing to the steel plate that rolls finished product thickness, and coating is the high temperature annealing separant of main component with MgO;
F. high temperature annealing and hot-leveling annealing, high temperature annealing routinely and hot-leveling technology are carried out.
2. the production method of an oriented silicon steel comprises the steps,
A. smelt, with converter or Electric furnace steel making, molten steel obtains strand behind secondary refining and continuous casting;
B. hot rolling, strand are heated to 1100~1200 ℃, and start rolling temperature is less than 1200 ℃, and finishing temperature is more than 850 ℃, and coiling temperature is below 650 ℃;
C. normalizing is handled, and hot-rolled sheet carries out 1050~1180 ℃ of 1~20 second and 850~950 ℃ of normalizing annealings of 30~200 seconds down down, and cools off fast, and speed of cooling is greater than 25 ℃/s;
D. cold rolling, use once or be with the above cold rolling process of secondary of process annealing to roll production board thickness, its final draft must surpass 80%;
E. nitriding, decarburization are carried out nitriding processing and decarburizing annealing to the steel plate that rolls finished product thickness, and coating is the high temperature annealing separant of main component with MgO;
F. high temperature annealing and hot-leveling annealing, high temperature annealing routinely and hot-leveling technology are carried out.
3. the production method of oriented silicon steel as claimed in claim 2 is characterized in that, described nitridation process comprises,
Heating zone dew point: below-20 ℃;
Nitriding temperature: 750~900 ℃;
Nitriding time: 5~50 seconds;
Nitriding medium: NH
3, require to use dried NH
3, dew point is below-20 ℃;
Protective atmosphere: H
2With N
2Mixed gas, H
2Content: 20~75%, below the atmosphere dew point-20 ℃, NH
3Concentration: 0.1~15%;
Nitriding amount: 50~200ppm.
4. the production method of oriented silicon steel as claimed in claim 2 is characterized in that, earlier decarburization is carried out in the steel plate nitriding again.
5. complex function annealing furnace, its body of heater comprises heating zone, nitriding section, decarbonization section and reduction section, it is characterized in that, three atmosphere disrupters are set between described heating zone, nitriding section, decarbonization section and the reduction section.
6. complex function annealing furnace as claimed in claim 5 is characterized in that, described atmosphere disrupter is a diaphragm structure.
7. complex function annealing furnace as claimed in claim 5 is characterized in that, described heating zone is radiator tube heating or electromagnetic induction heating.
8. complex function annealing furnace as claimed in claim 5 is characterized in that, described nitriding section, decarbonization section and reduction section adopt Electric heating.
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