CA2068592A1 - Method of producing grain-oriented electrical steel sheets or strips - Google Patents
Method of producing grain-oriented electrical steel sheets or stripsInfo
- Publication number
- CA2068592A1 CA2068592A1 CA002068592A CA2068592A CA2068592A1 CA 2068592 A1 CA2068592 A1 CA 2068592A1 CA 002068592 A CA002068592 A CA 002068592A CA 2068592 A CA2068592 A CA 2068592A CA 2068592 A1 CA2068592 A1 CA 2068592A1
- Authority
- CA
- Canada
- Prior art keywords
- strip
- annealing
- temperature
- range
- cold rolling
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
Links
- 238000000034 method Methods 0.000 title claims abstract description 41
- 229910001224 Grain-oriented electrical steel Inorganic materials 0.000 title claims abstract description 12
- 238000000137 annealing Methods 0.000 claims abstract description 87
- 238000005097 cold rolling Methods 0.000 claims abstract description 30
- 238000001816 cooling Methods 0.000 claims abstract description 30
- 238000005262 decarbonization Methods 0.000 claims abstract description 7
- 238000001953 recrystallisation Methods 0.000 claims abstract description 6
- 239000003795 chemical substances by application Substances 0.000 claims abstract description 5
- 239000012298 atmosphere Substances 0.000 claims abstract description 3
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims description 7
- 229910052799 carbon Inorganic materials 0.000 claims description 6
- 238000005098 hot rolling Methods 0.000 claims description 2
- 239000012535 impurity Substances 0.000 claims description 2
- 229910052742 iron Inorganic materials 0.000 claims description 2
- 238000005204 segregation Methods 0.000 claims description 2
- 230000009467 reduction Effects 0.000 abstract description 5
- 229910000831 Steel Inorganic materials 0.000 abstract description 4
- 239000010959 steel Substances 0.000 abstract description 4
- 238000005496 tempering Methods 0.000 abstract description 4
- 239000000203 mixture Substances 0.000 abstract description 3
- 230000008569 process Effects 0.000 description 21
- 230000010287 polarization Effects 0.000 description 12
- 238000004519 manufacturing process Methods 0.000 description 7
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 6
- 238000009826 distribution Methods 0.000 description 6
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 6
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 5
- 238000010438 heat treatment Methods 0.000 description 5
- 229910052739 hydrogen Inorganic materials 0.000 description 5
- 239000001257 hydrogen Substances 0.000 description 5
- 150000001247 metal acetylides Chemical class 0.000 description 5
- 239000006185 dispersion Substances 0.000 description 4
- 229910052757 nitrogen Inorganic materials 0.000 description 4
- 238000006722 reduction reaction Methods 0.000 description 4
- 229910000976 Electrical steel Inorganic materials 0.000 description 3
- 230000006872 improvement Effects 0.000 description 3
- 238000011835 investigation Methods 0.000 description 3
- 239000012299 nitrogen atmosphere Substances 0.000 description 3
- 238000001556 precipitation Methods 0.000 description 3
- 238000005507 spraying Methods 0.000 description 3
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 2
- 238000007796 conventional method Methods 0.000 description 2
- 230000007423 decrease Effects 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 101100073738 Escherichia coli (strain K12) kgtP gene Proteins 0.000 description 1
- OZBZONOEYUBXTD-UHFFFAOYSA-N OOOOOOOOO Chemical compound OOOOOOOOO OZBZONOEYUBXTD-UHFFFAOYSA-N 0.000 description 1
- 229910045601 alloy Inorganic materials 0.000 description 1
- 239000000956 alloy Substances 0.000 description 1
- 230000008901 benefit Effects 0.000 description 1
- 230000005540 biological transmission Effects 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 238000002149 energy-dispersive X-ray emission spectroscopy Methods 0.000 description 1
- 239000003112 inhibitor Substances 0.000 description 1
- 239000004922 lacquer Substances 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 239000000155 melt Substances 0.000 description 1
- 239000002245 particle Substances 0.000 description 1
- 238000005554 pickling Methods 0.000 description 1
- 230000005417 remagnetization Effects 0.000 description 1
- 238000005096 rolling process Methods 0.000 description 1
- 230000000087 stabilizing effect Effects 0.000 description 1
Classifications
-
- 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
- C21D8/1266—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 between cold rolling steps
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21B—ROLLING OF METAL
- B21B1/00—Metal-rolling methods or mills for making semi-finished products of solid or profiled cross-section; Sequence of operations in milling trains; Layout of rolling-mill plant, e.g. grouping of stands; Succession of passes or of sectional pass alternations
- B21B1/22—Metal-rolling methods or mills for making semi-finished products of solid or profiled cross-section; Sequence of operations in milling trains; Layout of rolling-mill plant, e.g. grouping of stands; Succession of passes or of sectional pass alternations for rolling plates, strips, bands or sheets of indefinite length
- B21B1/24—Metal-rolling methods or mills for making semi-finished products of solid or profiled cross-section; Sequence of operations in milling trains; Layout of rolling-mill plant, e.g. grouping of stands; Succession of passes or of sectional pass alternations for rolling plates, strips, bands or sheets of indefinite length in a continuous or semi-continuous process
- B21B1/28—Metal-rolling methods or mills for making semi-finished products of solid or profiled cross-section; Sequence of operations in milling trains; Layout of rolling-mill plant, e.g. grouping of stands; Succession of passes or of sectional pass alternations for rolling plates, strips, bands or sheets of indefinite length in a continuous or semi-continuous process by cold-rolling, e.g. Steckel cold mill
-
- 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
- C21D3/00—Diffusion processes for extraction of non-metals; Furnaces therefor
- C21D3/02—Extraction of non-metals
- C21D3/04—Decarburising
Landscapes
- Engineering & Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- Mechanical Engineering (AREA)
- Physics & Mathematics (AREA)
- Electromagnetism (AREA)
- Thermal Sciences (AREA)
- Manufacturing & Machinery (AREA)
- Crystallography & Structural Chemistry (AREA)
- Materials Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Manufacturing Of Steel Electrode Plates (AREA)
- Soft Magnetic Materials (AREA)
Abstract
METHOD OF PRODUCING GRAIN-ORIENTED ELECTRICAL STEEL
SHEETS OR STRIPS
ABSTRACT OF THE DISCLOSURE
The invention relates to a method of producing grain-oriented electrical steel sheets or strips having a final thickness in the range of 0.1 to 0.5 mm. A slab of a steel having the composition set forth in Claim 1 is hot rolled, then possibly annealed and then cold rolled In at least two stages with an intermediate annealing of the strip prior to the final cold rolling stage at a temperature in the range of 800 to 1100°C for 30 to 600 seconds and with an accelerated cooling from the intermediate annealing temperature at a speed higher than 50 K/sec. After a tempering annealing treatment prior to the final cold rolling stage, in which a thickness reduction of 40 to 80% is performed, a recrystallization annealing is carried out in a moist atmosphere, accompanied by the decarbonization of the strip cold rolled to the final thickness. After a separating agent has been applied to the strip surfaces, high temperature annealing is performed.
SHEETS OR STRIPS
ABSTRACT OF THE DISCLOSURE
The invention relates to a method of producing grain-oriented electrical steel sheets or strips having a final thickness in the range of 0.1 to 0.5 mm. A slab of a steel having the composition set forth in Claim 1 is hot rolled, then possibly annealed and then cold rolled In at least two stages with an intermediate annealing of the strip prior to the final cold rolling stage at a temperature in the range of 800 to 1100°C for 30 to 600 seconds and with an accelerated cooling from the intermediate annealing temperature at a speed higher than 50 K/sec. After a tempering annealing treatment prior to the final cold rolling stage, in which a thickness reduction of 40 to 80% is performed, a recrystallization annealing is carried out in a moist atmosphere, accompanied by the decarbonization of the strip cold rolled to the final thickness. After a separating agent has been applied to the strip surfaces, high temperature annealing is performed.
Description
2 ~ 2 .. -- 1 --BACKGROUND OF THE INVENTION
In the method known from European Patent 0 oL~7 129 for producing grain oriented electrical steel sheets or strips with a fina~ thickness in the range of 0.15 to 0.25 mm with at least two cold rolling stages and an intermediate annealing prior to the last cold rolling stage, said intermediate annealing is performed at a temperature in the range of 850 to 1100 C for at least 30 seconds to at most 15 minutes. Then the strip is cooled from the intermediate annealing temperature in the o o temperature range of 700 C to 200 C at a speed of at least 2.5 K/sec. and, without any subsequent tempering annealing treatment, rolled in the last cold rolling stage to the final thickness. During the cold rolling passes in said last cold rolling stage the strip temperature can be so adjusted as to lie in the range of 50 to 400 C.
In the comparable process, disclosed in European Patent 0 101 321 for the production of grain-oriented electrial steel sheets or strips with at least two cold rolling stages and an intermediate annealing prior to the last cold rolling stage, but also without temper annealing ~reatment prior to said last stage, a minimum speed of 5 K/sec is proposed for the rapid cooling o~ the strip from the intermediate annealing temperature. In that process the cooling speeds are preferably in the range o~
approximately 20 to 35 K/sec, to cool the strip following intermediate annealing over the temperature range of o o 900 C to 500 C. The characterizing feature of this process is the heating of the strip to the intermediate annealing temperature at a speed also preferably of approximately 20 to 35 K/sec.
If grain~oriented electrical steel sheets or strips are produced by the two aforementioned known methods - i.e., with a cooling ~rom the intermediate annealing temperature at a speed of 2.5 to approximately 40 K/sec, the magnetic property values, for example, the core loss, dif~er considerably. The reasons for this are the tolerances at each individual step o~ the process, e.g.
steel production/ composition of the melt, hot rolling, possibly hot strip annealing, cold rolling with intermediate annealing and also decarbonization annealing and high temperature annealing.
It is an object o~ the invention to improve the a~orementioned prior art methods that the magnetic properties of the electrical steel sheets or strips, more particularly magnetic polarization and core loss, reach more ~avourable values, while at the same time an improved statistical distribution o~ said values is achieved with less dispersion.
SUMMARY OF TH~ INVENTION
This problem is solved according to the invention by the following method:
A slab containing 2.0 to 4.0 % Si, 0.02 to 0.10 % C, 0.02 to 0.15 % Mn, o . oo8 to 0.08 % S and/or Se, max. 0.005 ~ Al, max. 0.3 % Cu, balance iron including unavoidable impurities and any grain boundary segregation elements - 3 - 2~ 9~
is hot rolled. The ho-t rolled strip may be annealed at a temperature in the range of 900 to 1100 C for 60 to 600 seconds. Then the hot strip is cold rolled in at least two cold rolling stages with an intermediate annealing of the strip at a temperature in the range of 800 to 1100 C
for 30 to 600 seconds prior to the last cold rolling stage and with a temper annealing treatmènt prior to the last cold rolling stage with a reduction in thickness of 40 to 80% in the last cold rolling stage. Prior to and/or during the cold rolling passes in the last cold rolling stage the temperature of the strip can preferably be adjusted ~o a value in the range of 50 to 400 C.
The strip cold rolled to its ~lnal thickness is then subjected to a recrystallization annealing in a moist atmosphere accompanied by decarbonization. The ~inal high temperature annealing is then performed after a separa~ing agent preferably containing ~gO has been applied to the strip surfaces.
The essential ~eature of the invention is that the strip, cold rolled to an intermediate thickness, is after the intermediate annealing subjected to accelerated cooling from the annealing temperature at a high speed of greater than 50 K/sec, preferably between 100 and 300 K/sec, and that after three months at the most ~ a tempering annealing treatment is performed in the temperature range of 300 to 700 C for at least 30 sec prior to the last cold rolling stage. Annealing for more than 15 minutes would be unoconomical. The accelerated cooling may be performed by spraying water.
The method according to the invention reduces the average values for the core loss.
~ 4 ~ 2 BRIEF DESCRIPTION OF THE DRAWINGS
Fig. 1 shows a statistical distribution of the measured core loss values for 141 strips of grain-oriented electrical steel with a final thickness of 0.23 mm, produced according to conventional methods, Fig. 2 shows the distribution of the core loss values of 141 strips of grain-oriented electrical steel with a final thickness of 0.23 mm as in ~ig. 1, but produced according to the invention, Fig. 3 combines the results set out in Fig. 1 and 2, Fig. 4 shows the reduction of the core loss values due to the method according to the invention, Fig. 5 shows the magnetic properties as a fuction of the cooling rate from the intermediate annealing temperature with the temper annealing, according to the invention and without such temper annealing, Fig. 6 shows the magnetic properties of strips with a final thickness of 0.3 mm in dependence to the temper annealing temperature.
DETAILED DESCRIPTION OF T~E DRAWINGS
From the shift in the maximum distribution as can be seen from Figs. 1 to 3 the application o~ the method according to the invention leads to an approximately 5%
improvement in the core loss. At the same time the magnetic values obtained are evened out - i.e., there is less dispersion.
2 ~ 2 As shown in Fig. 4, the erfect or the altered intermedlate annealing according to the invention (intermediate annealing witn high cooling speed and tne subsequent temper annealing treatmeni) takes place particuiarly clearly in the case or strips which show rather poorer loss values by the known, conventional production process. The maximum reduc-tions in the C~e remagnetization loss are achieved by means of the process according to the lnvention in the case of tne strips which show poor loss values in the known process.
The core loss P 1.7/50 with conventional production is plotted on the abscissa axis in Fig. 4. Plotted on the ordinate axis is tne reduction in loss (= quality improvement) wnich takes place when the same strips were treated ln the manner accordinq to the invention prior to the last cold rolling stage. ~ig. 4 is ~ased on the same data material as Fig. 3.
The same effect is also observed if the treatment according to the in~JentiOn is performed in directly successive steps, the strip being cooled as rapidly as possible from tne intermediate annealing temperature to a ~empera~ure equal to or slightly below the temperature of the temper annealing treatment, wnerearter tne temper annealin~ treatment is performed immediately. Tne important feature is in every case the co~inalion or rapid cooling from the intermediate annealina tempera~ure and the rollowing additional temper anneaiing treatment at a temperature in the range or 300 to 700C, preferably 450 to 650 C, prior to the last cold rolling stage.
In what follows the quality-enhancing efrect of the process according to the invention will be made clear with rererence to the em~odiments set fortn in Table 1, a comparison being made between grain-oriented electrical steel sneets (1.1), (2.1) and ~3.1) produced by the process according to the invention and electrical steel sheets (1.0), (2.0) and (3.0) produced by the known, conventional process.
(1.0) First oî all a hot strip having a thickness of 2.0 mm was produced rrom a continuously cast slab containing 3.19% Si, 0.031% C, 0.061% Mn, 0.021% S, 0.06% Cu, less than 0.002%
Al, less than 0.005% N, residue Fe. The hot strip was then annealed at 1030 C for 150 seconds in a dry hydrogen/
nitrogen aimosphere (approximately 5% ~2 + 95% N2), whereaîter cooling was perîormed slowly for 40 seconds in air at rest and then rapidly using sprayed water. After a surrace pickling a rirst cold rolling was perrormed to an intermediaie thickness or 0.65 mm. Then ihe conventional intermediate annealing was perîormed at 980~C for 180 seconds, also in a dry hydrog0n/nitrogen atmosphere (approximately 5% H2 + 95~ N2)- Cooling from the intermediate annealing temperature to room temperature was performed in air at rest at a speed or 20 Kjsec. ~fter t;ne 2 ~
second cola rolling to tne rinal thickness or 0.30 mm, tne decarbonization annealing was perrormed in a moist nydrogen~nitrogen atmosphere (approximately 20~ H2 + 80%
N2; dew point higner than 35 C) at 84 C ror 120 sec. Arter the application of a separating layer or MgO, high temperature annealing was perrormed in a dry, i00% hydrogen aimosphere. Then tne cold strip was heated to 1200 C at a heating rate OI approximately ~0 Kjh, maintained ror 2 h and then cooled slowly (stress-freej. The magnetic values deiermined gave a core loss P1.7j50 = 1.22 W/kg and a magnetic polarization B8 = l.a3 T.
(1.1) Furtner not strips used in accordance with (1.0) were processed in the same way, but with the dirrerence that aîter the intermediate annealing, the acceleraled cooling and subsequent temper annealing treatment according to the invention were used. The intermediate annealing was perrormed at a temperature of 1020 C, also ror 180 seconds in a dry hydrogen/nitrogen atmospnere (approximately 5% H2 + 95% N2). Tnen the cooling rrom the intermediate annealing temperature to room temperature oy means or sprayed water was perrormed at a speed or 110 ~/sec. Then tne temper annealing treatment according to the invention was carried out at ~00C in air for approximately 300 seconds. The heating and cooling speeds were approximately 10 K/sec. The magnetic values obtained by means of this process resulted in a core loss P1.7/50 =
1.1~ W/kg and a magnetic polarization B8 = 1.87 T.
2 ~
(2.0j A hot strip with a finai thickness or 2.0 mm was produced rrom a siab containing 3.16% ~i, 0.032~ C, 0.060% I~n, 0.020~ S, 0.055~ Cu, less than 0.002~ Al, iess Ihan 0.005 N, residue Fe. ~ubsequent hot strip annealing, the cold rolling to an intermediate thickness OI 0 . 65 mm, the intermediate annealing and the cooling to room temperature were performed as in Exampie (l.0). After cold roiling to the finai ihickness of 0.27 mm, tne decarbonization annealing, ihe application OI the separating agent and the high temperature annealing were perrormed as in Example ~1.0). Tne magnetic values OI t;ne strips thus produced gave a core loss Pl.7j50 = 1.19 Wjkg and a magnetic polarization B8 = 1.84 T.
(2.1) Ho~ s~rips according to (2.0) were processed in the same manner, ~ut again with the dif I erence thai the process accordin~ to the invention was used prior to the last cold rolling stage. The intermediate annealing was perIormed at a temperature OI 1020C, again for 180 seconds in a dry hydrogen/nitrogen aimosphere. Then cooling from the intermediate annealing temperature to room temperature was perrormed by spraying water at a speed or 120 K/sec. Tnen the strip was heat2d in air at 10 Kjsec to 600 C, neld at that iemperature for approximately 200 sec and recooled at the same speed. For the core loss and tne magnetic polarization, ihe following improved values were o~tained: Pl.7j50 = 1.08 W/kg and ~8 = 1.87 T.
- 9 - 2~ 2 (3.0) A not strip witA a final tnickness or` 2.0 mm was again produced rrom a contlnuously cast slab navina 3.23% Si, 0.030% C, 0.062% Mn, 0.020% S, 0.0~2% Cu, less than 0.002 Al, less tnan 0.005~ N, balance Fe. Subsequent hot sirip annealing, cold rolling io the intermediate thickness of 0.65 mm and the intermediate annealing were perrormed as in Examples (1.0) and (2.0) and cooling to room temperature was performed at a speed or 22 K/sec. Then the strip was cold rolled to tne final thickness or 0.23 mm. The decarbonization annealing, the application of the MgO
(separating ageni) and tne rollowing high temperature annealing were again performed in accordance with (1.0) and (2.0). The measured results were ror the core loss P1.7/50 = 1.06 W/kg and for magnetlc polarization e8 =
1.85 T.
(3.1) Strips first hot rolled, then annealed and then cold rolled to the intermediate thickness or 0.65 mm in accordance with (3.û) were annealed at a temperat:ure o~ 1020~C ~or 180 sec in a dry hydrogen/nitrogen atmosphere. Then cooling from this intermediate annealinq temperature to room temperature was performea ~y means of sprayed water at a speed OI
approximately 130 ~jsec. The rollowing temper annealing treatment was again perrormed as in Example (2.1). Arter the decar~onization and high temperature annealings according to (1.0), the results measured ror the resulting strips with an end taken as 0.23 mm were core loss P1.7/50 = 1.00 W/kg and magnetic polarization ~8 = 1.87 T.
Table 2 shows further grain-oriented electrical stee~l~s~n~ ~
produced bv the process according to the invention with a final tnickness OI ~ . 30 mm, witn iheir magnetic properties achieved.
They are compared with grain-oriented electrical steel sheets wi~h the same rinal ~hickness whicn were not produced by the process according to the invention.
As can be gathered from embodiments iO, 9, 8 and 7 in Taole 2 and the corresponding Fig. 5 J with rurther increasing values for the cooling speed, the core loss again rises and thererore deteriorates, unless tne temper annealing treatment according to the invention is used rollowing tne accelerated cooling ~rom the intermediate annealing temperature. Correspondingly, a decline in ihe direction of more unravourable values ror magnetic . . . _ polarization is discovered ir hign cooling speeds are used without any su~sequent temper annealing treatment according to the invention.
IL^, in contrast and according to the, process claimed, high cooling speeds are combined witn the rollowing temper annealing treatment according to the invention in tne temperature range o~ 300 to 700C, as embodiments 3, 1 and 2 in TaDle 2 and ~ig. 5 show, tne core losses measured continue to decline in the direction of lower and thererore more ravourable values. Correspondingly, the measured values ror ~agnetic polarization advantageously continue ~o increase in the direction or higher values.
Table 2 also shows the temperature range for the temper anneaiing treatment according to the invention, which is shown in graph ~rom in Fig. 6. Accordingly, the mos~ îavourable values for the core loss and magnetic polarization are reacned iI the temper annealing treatment OI the strip cold rolled to an intermediate thic~ness is per~ormed in the temperature range OI 450 to 650C, more particularly at a temperature of about 600 C, rollowing the accelerated cooling from the intermediate anneaiing temperature by means OI spraying water at a speed prererably higher than 100 K/sec.
The change in the intermediate annealing according to the invention, followed by accelerated cooling and temper annealing treatment improves the texture formation of grain-oriented electrical steel sheets with the stated alloy composition claimed, in comparison with conventional intermediate annealing. ~he efrec~ of the intermediate annealing modified according to the invention consists in a more ~avourable carbide precipitation, as numerous mlcrostructure investigations have shown.
An investigation of the cold rolling textures o~ the strips in the condiiion rollowing the last cold roiling arter a preceding conventional method oî produciion and a meihod according to the invention gave substantially identical textural courses.
However, an investigation or the texture o~ the corresponding decarbonized cold strips show clear dlrrerences in the Goss intensity, which in the case or grain-orientated electric quality sheets is a particularly important recrystallization - 12 ~
textural componeni in the decarbonized cold slrip. lt is distinctiy higner when the production process according to the invention is used.
the transmission ~lectron mi~oscoF
The carbon precipitation state wa5 investigated in/using lacquer replicas, directly arter the conventional intermediale annealing and after the i~proved type or intermediate annealing according to the invention.
An eiement-dispersive EDX analysis (STEM mode~ showed that carbides were to be round solely at the grain boundaries, independently of the kind of intermediate annealing.
In the conventional production method the grain boundary carbides .. .. . _ .. . . . .... . _ .
have length of 200 to 1000 nm ~typically 500 nm), while following tne intermediate annealing according to the invention (with accelerated cooling and tempering annealing treatment) they have lengths of 50 to 200 nm (typically 100 nm). In both cases the precipitations inside the grains are exclusively particles o~ the inhibitor phase, which is not af~ected by the ~eihod or treatment according to the invention. The fine dispersion and unifor~ity of distribution OI the grain boundary carbides is appreciably enhanced by the process according to the invention.
The result OI the type or intermediate annealing proposed according to the invention is that the carbon~ which is bonded in the substantially more ~inely distriDu~ed carbides, dissolves very much ~ore rapidly than in the conventional process in the heating phase or tne de~arbonizaiion annealing (prior to tne - 13 - 2~
start of recrysiallization). This is supported by the very much more unirorm distribution at the grain bcundaries.
The carbides do not inîluence tne process or cold rolling, but they have an effect on the recrystallization process. The recrystailization texture is sharpened; more Goss-oriented nuclei are produced i~proving the follo~ina seeondary recrystallization.
In addition to the process steps claimed according to the invention, in tne production of grain-oriented electrical steel sheets with a final thickness in the range or 0.1 to 0.5 mm, other steps have become known which can lead to an improvement in their magnetic properties. For example, tne values or the core ~ loss can be further reduced if during the conventional intermediate annealing of the strip cold rolled to an intermediate thickness, the strip is at the same time partially desarbonized. Similarly, the coreloss is reduced ir additional holding stages lastin~ several hours are interpolated in the course of the hign temperature box annealing during the heating phase. Combinations or these additional steps have also become known.
In contrast, in the process according to the invention such additional steps are not necessarily required, more particularly to achieve the aforedescribed stability of the magnetic properties or grain-oriented electrical steel sneets, as shown by a selection of 1~1 difrerent stripsO To advantaseously reduce tne statistical dispersion or the values ootained for the -- l d ~ t,~
core loss and magnetic polarization, ii is enough in the process according to the invention to provide tne proposed rapid cooling in comDination with the foilowing temper annealing treatment according to the invention arter conventional intermediate annealing has been perlormed. The essential advantage of the process according to the invention is thererore tne stabilizing erfect in the produciion or grain-oriented electricai steel sneets on their magnetic properties, such as core loss and magnetic polarization.
.
x x 8 o ~ .
O ~ 3 X X X O V
Q ~
V E~ co a~ ~ u~ ~
. h~ ~ .~ .
~ Y ~ ~ co o~ O ~o . ~ r S ~ ~ ~I O ~ O O G~ ~
~ N ~I ~
U~-SV ~ O O O U~ 3 ,_1 a~bO o ~ o I o I .
bO ~ O I O ~ O I -1 il~ C) ~ O I
~ l rl ~1 O
c-: ~ c) O O O o o ~I , a~
t~ OJ_~ ~ \J .
r S_ S_ O :; ~
S ~ ~ ~ ~ O
o O ~ 1 a~
1~: C~ 3 ¢ 3 ¢ 3 ¢
hq~a o o o o o o ,a a O o a~ o a~ o o~ ~ I s o c~
_ 16- 2~
Z ~ 1 3 U~ 0 C~ O '- ~
, O O
O X X
S: ~ ' O ~cx X X X X E
o ~n ~ ~ ~ ~ 3` ci~ o~ =r ~ ~- O C~ ) 0O ~ ~ 0~ U) .~
a~ ~ ~ ~ ~ ~ .C~ ~ o . 1~0 ~'J ~ O ~ O t~ s ,~
.,_.--:.-.. - -- .. _ ,~
~: ~ ~ ~OOOOOOOOO ~V ~/
~ S Ç O o o o o o o ô c~ o O O E "_, Q)V
o O o o o o ~ r ~v~
~ ~ ~-- O O U~ O O CJ~ O O 15~ O O a~ O ~ D ~
s: ~o ~ ~ s a~
(: O ~ V S S.. ~ ~ ~ ~ S, S~. S S ~ D
D W ~ NO O O O O O O O O O O ~ ~ S Y
o u~ â D
In the method known from European Patent 0 oL~7 129 for producing grain oriented electrical steel sheets or strips with a fina~ thickness in the range of 0.15 to 0.25 mm with at least two cold rolling stages and an intermediate annealing prior to the last cold rolling stage, said intermediate annealing is performed at a temperature in the range of 850 to 1100 C for at least 30 seconds to at most 15 minutes. Then the strip is cooled from the intermediate annealing temperature in the o o temperature range of 700 C to 200 C at a speed of at least 2.5 K/sec. and, without any subsequent tempering annealing treatment, rolled in the last cold rolling stage to the final thickness. During the cold rolling passes in said last cold rolling stage the strip temperature can be so adjusted as to lie in the range of 50 to 400 C.
In the comparable process, disclosed in European Patent 0 101 321 for the production of grain-oriented electrial steel sheets or strips with at least two cold rolling stages and an intermediate annealing prior to the last cold rolling stage, but also without temper annealing ~reatment prior to said last stage, a minimum speed of 5 K/sec is proposed for the rapid cooling o~ the strip from the intermediate annealing temperature. In that process the cooling speeds are preferably in the range o~
approximately 20 to 35 K/sec, to cool the strip following intermediate annealing over the temperature range of o o 900 C to 500 C. The characterizing feature of this process is the heating of the strip to the intermediate annealing temperature at a speed also preferably of approximately 20 to 35 K/sec.
If grain~oriented electrical steel sheets or strips are produced by the two aforementioned known methods - i.e., with a cooling ~rom the intermediate annealing temperature at a speed of 2.5 to approximately 40 K/sec, the magnetic property values, for example, the core loss, dif~er considerably. The reasons for this are the tolerances at each individual step o~ the process, e.g.
steel production/ composition of the melt, hot rolling, possibly hot strip annealing, cold rolling with intermediate annealing and also decarbonization annealing and high temperature annealing.
It is an object o~ the invention to improve the a~orementioned prior art methods that the magnetic properties of the electrical steel sheets or strips, more particularly magnetic polarization and core loss, reach more ~avourable values, while at the same time an improved statistical distribution o~ said values is achieved with less dispersion.
SUMMARY OF TH~ INVENTION
This problem is solved according to the invention by the following method:
A slab containing 2.0 to 4.0 % Si, 0.02 to 0.10 % C, 0.02 to 0.15 % Mn, o . oo8 to 0.08 % S and/or Se, max. 0.005 ~ Al, max. 0.3 % Cu, balance iron including unavoidable impurities and any grain boundary segregation elements - 3 - 2~ 9~
is hot rolled. The ho-t rolled strip may be annealed at a temperature in the range of 900 to 1100 C for 60 to 600 seconds. Then the hot strip is cold rolled in at least two cold rolling stages with an intermediate annealing of the strip at a temperature in the range of 800 to 1100 C
for 30 to 600 seconds prior to the last cold rolling stage and with a temper annealing treatmènt prior to the last cold rolling stage with a reduction in thickness of 40 to 80% in the last cold rolling stage. Prior to and/or during the cold rolling passes in the last cold rolling stage the temperature of the strip can preferably be adjusted ~o a value in the range of 50 to 400 C.
The strip cold rolled to its ~lnal thickness is then subjected to a recrystallization annealing in a moist atmosphere accompanied by decarbonization. The ~inal high temperature annealing is then performed after a separa~ing agent preferably containing ~gO has been applied to the strip surfaces.
The essential ~eature of the invention is that the strip, cold rolled to an intermediate thickness, is after the intermediate annealing subjected to accelerated cooling from the annealing temperature at a high speed of greater than 50 K/sec, preferably between 100 and 300 K/sec, and that after three months at the most ~ a tempering annealing treatment is performed in the temperature range of 300 to 700 C for at least 30 sec prior to the last cold rolling stage. Annealing for more than 15 minutes would be unoconomical. The accelerated cooling may be performed by spraying water.
The method according to the invention reduces the average values for the core loss.
~ 4 ~ 2 BRIEF DESCRIPTION OF THE DRAWINGS
Fig. 1 shows a statistical distribution of the measured core loss values for 141 strips of grain-oriented electrical steel with a final thickness of 0.23 mm, produced according to conventional methods, Fig. 2 shows the distribution of the core loss values of 141 strips of grain-oriented electrical steel with a final thickness of 0.23 mm as in ~ig. 1, but produced according to the invention, Fig. 3 combines the results set out in Fig. 1 and 2, Fig. 4 shows the reduction of the core loss values due to the method according to the invention, Fig. 5 shows the magnetic properties as a fuction of the cooling rate from the intermediate annealing temperature with the temper annealing, according to the invention and without such temper annealing, Fig. 6 shows the magnetic properties of strips with a final thickness of 0.3 mm in dependence to the temper annealing temperature.
DETAILED DESCRIPTION OF T~E DRAWINGS
From the shift in the maximum distribution as can be seen from Figs. 1 to 3 the application o~ the method according to the invention leads to an approximately 5%
improvement in the core loss. At the same time the magnetic values obtained are evened out - i.e., there is less dispersion.
2 ~ 2 As shown in Fig. 4, the erfect or the altered intermedlate annealing according to the invention (intermediate annealing witn high cooling speed and tne subsequent temper annealing treatmeni) takes place particuiarly clearly in the case or strips which show rather poorer loss values by the known, conventional production process. The maximum reduc-tions in the C~e remagnetization loss are achieved by means of the process according to the lnvention in the case of tne strips which show poor loss values in the known process.
The core loss P 1.7/50 with conventional production is plotted on the abscissa axis in Fig. 4. Plotted on the ordinate axis is tne reduction in loss (= quality improvement) wnich takes place when the same strips were treated ln the manner accordinq to the invention prior to the last cold rolling stage. ~ig. 4 is ~ased on the same data material as Fig. 3.
The same effect is also observed if the treatment according to the in~JentiOn is performed in directly successive steps, the strip being cooled as rapidly as possible from tne intermediate annealing temperature to a ~empera~ure equal to or slightly below the temperature of the temper annealing treatment, wnerearter tne temper annealin~ treatment is performed immediately. Tne important feature is in every case the co~inalion or rapid cooling from the intermediate annealina tempera~ure and the rollowing additional temper anneaiing treatment at a temperature in the range or 300 to 700C, preferably 450 to 650 C, prior to the last cold rolling stage.
In what follows the quality-enhancing efrect of the process according to the invention will be made clear with rererence to the em~odiments set fortn in Table 1, a comparison being made between grain-oriented electrical steel sneets (1.1), (2.1) and ~3.1) produced by the process according to the invention and electrical steel sheets (1.0), (2.0) and (3.0) produced by the known, conventional process.
(1.0) First oî all a hot strip having a thickness of 2.0 mm was produced rrom a continuously cast slab containing 3.19% Si, 0.031% C, 0.061% Mn, 0.021% S, 0.06% Cu, less than 0.002%
Al, less than 0.005% N, residue Fe. The hot strip was then annealed at 1030 C for 150 seconds in a dry hydrogen/
nitrogen aimosphere (approximately 5% ~2 + 95% N2), whereaîter cooling was perîormed slowly for 40 seconds in air at rest and then rapidly using sprayed water. After a surrace pickling a rirst cold rolling was perrormed to an intermediaie thickness or 0.65 mm. Then ihe conventional intermediate annealing was perîormed at 980~C for 180 seconds, also in a dry hydrog0n/nitrogen atmosphere (approximately 5% H2 + 95~ N2)- Cooling from the intermediate annealing temperature to room temperature was performed in air at rest at a speed or 20 Kjsec. ~fter t;ne 2 ~
second cola rolling to tne rinal thickness or 0.30 mm, tne decarbonization annealing was perrormed in a moist nydrogen~nitrogen atmosphere (approximately 20~ H2 + 80%
N2; dew point higner than 35 C) at 84 C ror 120 sec. Arter the application of a separating layer or MgO, high temperature annealing was perrormed in a dry, i00% hydrogen aimosphere. Then tne cold strip was heated to 1200 C at a heating rate OI approximately ~0 Kjh, maintained ror 2 h and then cooled slowly (stress-freej. The magnetic values deiermined gave a core loss P1.7j50 = 1.22 W/kg and a magnetic polarization B8 = l.a3 T.
(1.1) Furtner not strips used in accordance with (1.0) were processed in the same way, but with the dirrerence that aîter the intermediate annealing, the acceleraled cooling and subsequent temper annealing treatment according to the invention were used. The intermediate annealing was perrormed at a temperature of 1020 C, also ror 180 seconds in a dry hydrogen/nitrogen atmospnere (approximately 5% H2 + 95% N2). Tnen the cooling rrom the intermediate annealing temperature to room temperature oy means or sprayed water was perrormed at a speed or 110 ~/sec. Then tne temper annealing treatment according to the invention was carried out at ~00C in air for approximately 300 seconds. The heating and cooling speeds were approximately 10 K/sec. The magnetic values obtained by means of this process resulted in a core loss P1.7/50 =
1.1~ W/kg and a magnetic polarization B8 = 1.87 T.
2 ~
(2.0j A hot strip with a finai thickness or 2.0 mm was produced rrom a siab containing 3.16% ~i, 0.032~ C, 0.060% I~n, 0.020~ S, 0.055~ Cu, less than 0.002~ Al, iess Ihan 0.005 N, residue Fe. ~ubsequent hot strip annealing, the cold rolling to an intermediate thickness OI 0 . 65 mm, the intermediate annealing and the cooling to room temperature were performed as in Exampie (l.0). After cold roiling to the finai ihickness of 0.27 mm, tne decarbonization annealing, ihe application OI the separating agent and the high temperature annealing were perrormed as in Example ~1.0). Tne magnetic values OI t;ne strips thus produced gave a core loss Pl.7j50 = 1.19 Wjkg and a magnetic polarization B8 = 1.84 T.
(2.1) Ho~ s~rips according to (2.0) were processed in the same manner, ~ut again with the dif I erence thai the process accordin~ to the invention was used prior to the last cold rolling stage. The intermediate annealing was perIormed at a temperature OI 1020C, again for 180 seconds in a dry hydrogen/nitrogen aimosphere. Then cooling from the intermediate annealing temperature to room temperature was perrormed by spraying water at a speed or 120 K/sec. Tnen the strip was heat2d in air at 10 Kjsec to 600 C, neld at that iemperature for approximately 200 sec and recooled at the same speed. For the core loss and tne magnetic polarization, ihe following improved values were o~tained: Pl.7j50 = 1.08 W/kg and ~8 = 1.87 T.
- 9 - 2~ 2 (3.0) A not strip witA a final tnickness or` 2.0 mm was again produced rrom a contlnuously cast slab navina 3.23% Si, 0.030% C, 0.062% Mn, 0.020% S, 0.0~2% Cu, less than 0.002 Al, less tnan 0.005~ N, balance Fe. Subsequent hot sirip annealing, cold rolling io the intermediate thickness of 0.65 mm and the intermediate annealing were perrormed as in Examples (1.0) and (2.0) and cooling to room temperature was performed at a speed or 22 K/sec. Then the strip was cold rolled to tne final thickness or 0.23 mm. The decarbonization annealing, the application of the MgO
(separating ageni) and tne rollowing high temperature annealing were again performed in accordance with (1.0) and (2.0). The measured results were ror the core loss P1.7/50 = 1.06 W/kg and for magnetlc polarization e8 =
1.85 T.
(3.1) Strips first hot rolled, then annealed and then cold rolled to the intermediate thickness or 0.65 mm in accordance with (3.û) were annealed at a temperat:ure o~ 1020~C ~or 180 sec in a dry hydrogen/nitrogen atmosphere. Then cooling from this intermediate annealinq temperature to room temperature was performea ~y means of sprayed water at a speed OI
approximately 130 ~jsec. The rollowing temper annealing treatment was again perrormed as in Example (2.1). Arter the decar~onization and high temperature annealings according to (1.0), the results measured ror the resulting strips with an end taken as 0.23 mm were core loss P1.7/50 = 1.00 W/kg and magnetic polarization ~8 = 1.87 T.
Table 2 shows further grain-oriented electrical stee~l~s~n~ ~
produced bv the process according to the invention with a final tnickness OI ~ . 30 mm, witn iheir magnetic properties achieved.
They are compared with grain-oriented electrical steel sheets wi~h the same rinal ~hickness whicn were not produced by the process according to the invention.
As can be gathered from embodiments iO, 9, 8 and 7 in Taole 2 and the corresponding Fig. 5 J with rurther increasing values for the cooling speed, the core loss again rises and thererore deteriorates, unless tne temper annealing treatment according to the invention is used rollowing tne accelerated cooling ~rom the intermediate annealing temperature. Correspondingly, a decline in ihe direction of more unravourable values ror magnetic . . . _ polarization is discovered ir hign cooling speeds are used without any su~sequent temper annealing treatment according to the invention.
IL^, in contrast and according to the, process claimed, high cooling speeds are combined witn the rollowing temper annealing treatment according to the invention in tne temperature range o~ 300 to 700C, as embodiments 3, 1 and 2 in TaDle 2 and ~ig. 5 show, tne core losses measured continue to decline in the direction of lower and thererore more ravourable values. Correspondingly, the measured values ror ~agnetic polarization advantageously continue ~o increase in the direction or higher values.
Table 2 also shows the temperature range for the temper anneaiing treatment according to the invention, which is shown in graph ~rom in Fig. 6. Accordingly, the mos~ îavourable values for the core loss and magnetic polarization are reacned iI the temper annealing treatment OI the strip cold rolled to an intermediate thic~ness is per~ormed in the temperature range OI 450 to 650C, more particularly at a temperature of about 600 C, rollowing the accelerated cooling from the intermediate anneaiing temperature by means OI spraying water at a speed prererably higher than 100 K/sec.
The change in the intermediate annealing according to the invention, followed by accelerated cooling and temper annealing treatment improves the texture formation of grain-oriented electrical steel sheets with the stated alloy composition claimed, in comparison with conventional intermediate annealing. ~he efrec~ of the intermediate annealing modified according to the invention consists in a more ~avourable carbide precipitation, as numerous mlcrostructure investigations have shown.
An investigation of the cold rolling textures o~ the strips in the condiiion rollowing the last cold roiling arter a preceding conventional method oî produciion and a meihod according to the invention gave substantially identical textural courses.
However, an investigation or the texture o~ the corresponding decarbonized cold strips show clear dlrrerences in the Goss intensity, which in the case or grain-orientated electric quality sheets is a particularly important recrystallization - 12 ~
textural componeni in the decarbonized cold slrip. lt is distinctiy higner when the production process according to the invention is used.
the transmission ~lectron mi~oscoF
The carbon precipitation state wa5 investigated in/using lacquer replicas, directly arter the conventional intermediale annealing and after the i~proved type or intermediate annealing according to the invention.
An eiement-dispersive EDX analysis (STEM mode~ showed that carbides were to be round solely at the grain boundaries, independently of the kind of intermediate annealing.
In the conventional production method the grain boundary carbides .. .. . _ .. . . . .... . _ .
have length of 200 to 1000 nm ~typically 500 nm), while following tne intermediate annealing according to the invention (with accelerated cooling and tempering annealing treatment) they have lengths of 50 to 200 nm (typically 100 nm). In both cases the precipitations inside the grains are exclusively particles o~ the inhibitor phase, which is not af~ected by the ~eihod or treatment according to the invention. The fine dispersion and unifor~ity of distribution OI the grain boundary carbides is appreciably enhanced by the process according to the invention.
The result OI the type or intermediate annealing proposed according to the invention is that the carbon~ which is bonded in the substantially more ~inely distriDu~ed carbides, dissolves very much ~ore rapidly than in the conventional process in the heating phase or tne de~arbonizaiion annealing (prior to tne - 13 - 2~
start of recrysiallization). This is supported by the very much more unirorm distribution at the grain bcundaries.
The carbides do not inîluence tne process or cold rolling, but they have an effect on the recrystallization process. The recrystailization texture is sharpened; more Goss-oriented nuclei are produced i~proving the follo~ina seeondary recrystallization.
In addition to the process steps claimed according to the invention, in tne production of grain-oriented electrical steel sheets with a final thickness in the range or 0.1 to 0.5 mm, other steps have become known which can lead to an improvement in their magnetic properties. For example, tne values or the core ~ loss can be further reduced if during the conventional intermediate annealing of the strip cold rolled to an intermediate thickness, the strip is at the same time partially desarbonized. Similarly, the coreloss is reduced ir additional holding stages lastin~ several hours are interpolated in the course of the hign temperature box annealing during the heating phase. Combinations or these additional steps have also become known.
In contrast, in the process according to the invention such additional steps are not necessarily required, more particularly to achieve the aforedescribed stability of the magnetic properties or grain-oriented electrical steel sneets, as shown by a selection of 1~1 difrerent stripsO To advantaseously reduce tne statistical dispersion or the values ootained for the -- l d ~ t,~
core loss and magnetic polarization, ii is enough in the process according to the invention to provide tne proposed rapid cooling in comDination with the foilowing temper annealing treatment according to the invention arter conventional intermediate annealing has been perlormed. The essential advantage of the process according to the invention is thererore tne stabilizing erfect in the produciion or grain-oriented electricai steel sneets on their magnetic properties, such as core loss and magnetic polarization.
.
x x 8 o ~ .
O ~ 3 X X X O V
Q ~
V E~ co a~ ~ u~ ~
. h~ ~ .~ .
~ Y ~ ~ co o~ O ~o . ~ r S ~ ~ ~I O ~ O O G~ ~
~ N ~I ~
U~-SV ~ O O O U~ 3 ,_1 a~bO o ~ o I o I .
bO ~ O I O ~ O I -1 il~ C) ~ O I
~ l rl ~1 O
c-: ~ c) O O O o o ~I , a~
t~ OJ_~ ~ \J .
r S_ S_ O :; ~
S ~ ~ ~ ~ O
o O ~ 1 a~
1~: C~ 3 ¢ 3 ¢ 3 ¢
hq~a o o o o o o ,a a O o a~ o a~ o o~ ~ I s o c~
_ 16- 2~
Z ~ 1 3 U~ 0 C~ O '- ~
, O O
O X X
S: ~ ' O ~cx X X X X E
o ~n ~ ~ ~ ~ 3` ci~ o~ =r ~ ~- O C~ ) 0O ~ ~ 0~ U) .~
a~ ~ ~ ~ ~ ~ .C~ ~ o . 1~0 ~'J ~ O ~ O t~ s ,~
.,_.--:.-.. - -- .. _ ,~
~: ~ ~ ~OOOOOOOOO ~V ~/
~ S Ç O o o o o o o ô c~ o O O E "_, Q)V
o O o o o o ~ r ~v~
~ ~ ~-- O O U~ O O CJ~ O O 15~ O O a~ O ~ D ~
s: ~o ~ ~ s a~
(: O ~ V S S.. ~ ~ ~ ~ S, S~. S S ~ D
D W ~ NO O O O O O O O O O O ~ ~ S Y
o u~ â D
Claims (9)
1. A method of producing grain-oriented electrical steel sheets or strips having a final thickness in the range of 0.1 to 0.5 mm, by hot rolling a slab which contains
2.0 to 4.0 % Si, 0.02 to 0.10 % C, 0.02 to 0.15 % Mn, 0.008 to 0.08 % S and/or Se, max. 0.005 % Al;
max. 0.3 % Cu balance iron including unavoidable impurities, and any grain boundary segregation elements, cold rolling the hot strip in at least two cold rolling stages with an intermediate annealing of the strip at a temperature in the range of 800 to 1100°C for 30 to 600 seconds and accelerated cooling prior to the last cold rolling stage, recrystallization annealing in a moist atmosphere with decarbonization of the strip cold rolled to the final thickness, applying a separating agent to the strip surface and finally high temperature annealing, characterized in that cooling is performed from the intermediate annealing temperature at a speed greater than 50 K/sec, and temper annealing immediately thereafter or after 3 months at the most in the temperature range of 300 to 700°C for at least 30 seconds prior to the last cold rolling stage, in which the thickness is reduced from 40 to 80 %.
2. A method according to claim 1, characterized in that the strip is subjected to accelerated cooling immediately from the intermediate annealing temperature to the temperature of the temper annealing treatment.
max. 0.3 % Cu balance iron including unavoidable impurities, and any grain boundary segregation elements, cold rolling the hot strip in at least two cold rolling stages with an intermediate annealing of the strip at a temperature in the range of 800 to 1100°C for 30 to 600 seconds and accelerated cooling prior to the last cold rolling stage, recrystallization annealing in a moist atmosphere with decarbonization of the strip cold rolled to the final thickness, applying a separating agent to the strip surface and finally high temperature annealing, characterized in that cooling is performed from the intermediate annealing temperature at a speed greater than 50 K/sec, and temper annealing immediately thereafter or after 3 months at the most in the temperature range of 300 to 700°C for at least 30 seconds prior to the last cold rolling stage, in which the thickness is reduced from 40 to 80 %.
2. A method according to claim 1, characterized in that the strip is subjected to accelerated cooling immediately from the intermediate annealing temperature to the temperature of the temper annealing treatment.
3. A method according to claim 1, characterized in that the strip is subjected to accelerated cooling at a speed in the range of 100 to 300 K/sec.
4. A method according to claim 1, characterized in that the temper annealing is performed in the temperature range of 450 to 650°C for 100 to 600 sec.
5. A method according to claim 1, characterized in that the strip is heated to the temperature of the temper annealing treatment at a speed of 2.5 to 20 K/sec and recooled at the same speed.
6. A method according to claim 1, characterized in that the hot rolled strip is annealed at a temperature in the range of 900 to 1100°C for 60 to 600 seconds.
7. A method according to claim 1, characterized in that the strip is rolled during the last cold rolling stage, at a temperature in the range of 50 to 400°C.
8. A method according to claim 1, characterized in that a separating agent containing MgO is applied to the surface of the strip.
9. A method according to claim 1, characterized in that the temper annealing is performed for not more than 15 minutes.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE4116240A DE4116240A1 (en) | 1991-05-17 | 1991-05-17 | METHOD FOR PRODUCING CORNORIENTED ELECTRIC SHEETS |
| DEP4116240.4-24 | 1991-05-17 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2068592A1 true CA2068592A1 (en) | 1992-11-18 |
Family
ID=6431924
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002068592A Abandoned CA2068592A1 (en) | 1991-05-17 | 1992-05-13 | Method of producing grain-oriented electrical steel sheets or strips |
Country Status (9)
| Country | Link |
|---|---|
| EP (1) | EP0513729A1 (en) |
| JP (1) | JPH0797629A (en) |
| KR (1) | KR920021230A (en) |
| CN (1) | CN1069288A (en) |
| BR (1) | BR9201867A (en) |
| CA (1) | CA2068592A1 (en) |
| CS (1) | CS146992A3 (en) |
| DE (1) | DE4116240A1 (en) |
| PL (1) | PL294562A1 (en) |
Families Citing this family (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE4311151C1 (en) * | 1993-04-05 | 1994-07-28 | Thyssen Stahl Ag | Grain-orientated electro-steel sheets with good properties |
| US6309473B1 (en) * | 1998-10-09 | 2001-10-30 | Kawasaki Steel Corporation | Method of making grain-oriented magnetic steel sheet having low iron loss |
| BRPI0711794B1 (en) * | 2006-05-24 | 2015-12-08 | Nippon Steel & Sumitomo Metal Corp | method for producing grain oriented magnetic steel sheet having a high magnetic flux density |
| CN102962267B (en) * | 2012-11-27 | 2014-09-03 | 南京钢铁股份有限公司 | Cooling control process for preventing decarbonization of small-size spring steel |
Family Cites Families (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5920745B2 (en) * | 1980-08-27 | 1984-05-15 | 川崎製鉄株式会社 | Unidirectional silicon steel plate with extremely low iron loss and its manufacturing method |
| EP0101321B1 (en) * | 1982-08-18 | 1990-12-05 | Kawasaki Steel Corporation | Method of producing grain oriented silicon steel sheets or strips having high magnetic induction and low iron loss |
| US4478653A (en) * | 1983-03-10 | 1984-10-23 | Armco Inc. | Process for producing grain-oriented silicon steel |
| DE3666229D1 (en) * | 1985-02-22 | 1989-11-16 | Kawasaki Steel Co | Extra-low iron loss grain oriented silicon steel sheets |
| US4975127A (en) * | 1987-05-11 | 1990-12-04 | Kawasaki Steel Corp. | Method of producing grain oriented silicon steel sheets having magnetic properties |
-
1991
- 1991-05-17 DE DE4116240A patent/DE4116240A1/en active Granted
-
1992
- 1992-05-12 EP EP92107972A patent/EP0513729A1/en not_active Withdrawn
- 1992-05-13 CA CA002068592A patent/CA2068592A1/en not_active Abandoned
- 1992-05-14 JP JP4146769A patent/JPH0797629A/en active Pending
- 1992-05-15 CS CS921469A patent/CS146992A3/en unknown
- 1992-05-15 PL PL29456292A patent/PL294562A1/xx unknown
- 1992-05-16 KR KR1019920008320A patent/KR920021230A/en not_active Withdrawn
- 1992-05-16 CN CN92104298A patent/CN1069288A/en active Pending
- 1992-05-18 BR BR929201867A patent/BR9201867A/en not_active Application Discontinuation
Also Published As
| Publication number | Publication date |
|---|---|
| PL294562A1 (en) | 1993-02-08 |
| JPH0797629A (en) | 1995-04-11 |
| DE4116240C2 (en) | 1993-07-08 |
| CS146992A3 (en) | 1992-11-18 |
| KR920021230A (en) | 1992-12-18 |
| EP0513729A1 (en) | 1992-11-19 |
| BR9201867A (en) | 1993-01-05 |
| CN1069288A (en) | 1993-02-24 |
| DE4116240A1 (en) | 1992-11-19 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| KR100352675B1 (en) | Method of producing grain-oriented magnetic steel sheet | |
| US5803988A (en) | Method for manufacturing non-oriented electrical steel sheet showing superior adherence of insulating coated layer | |
| US5039359A (en) | Procees for producing grain-oriented electrical steel sheet having superior magnetic characteristic | |
| US5261972A (en) | Process for producing grain-oriented electrical steel strip having high magnetic flux density | |
| JP7583815B2 (en) | Bi-directional electrical steel sheet and its manufacturing method | |
| JPH059580A (en) | Method for manufacturing thin grain silicon steel sheet with excellent magnetic properties | |
| EP0475710B1 (en) | Method of manufacturing an oriented silicon steel sheet having improved magnetic characteristics | |
| US5667598A (en) | Production method for grain oriented silicion steel sheet having excellent magnetic characteristics | |
| CA2068592A1 (en) | Method of producing grain-oriented electrical steel sheets or strips | |
| JP2648424B2 (en) | Method for manufacturing oriented silicon thin steel sheet with excellent magnetic properties | |
| KR100940718B1 (en) | Method for manufacturing oriented electrical steel sheet by omitting hot rolled sheet | |
| JP2002212635A (en) | Method for producing unidirectional silicon steel sheet with excellent magnetic properties | |
| JPH02196403A (en) | High magnetic flux density anisotropic silicon steel plate excellent in iron loss characteristic and manufacture thereof | |
| KR100544637B1 (en) | Manufacturing method of oriented electrical steel sheet with excellent magnetic properties | |
| KR100514790B1 (en) | A method for manufacturing grain-oriented electrical steel sheet with superior magnetic property using the low temperature heating method | |
| JPH10110218A (en) | Manufacturing method of grain-oriented electrical steel sheet with excellent magnetic properties | |
| KR20000008646A (en) | Process for preparing directional electrical sheet having a good magnetic property and productibilities by slab low temperature reheating | |
| KR970007031B1 (en) | Method for manufacturing orient electrical steel sheet having excellent magnetic properties | |
| KR100237158B1 (en) | The manufacturing method for oriented electric steel sheet with excellent magnetic property | |
| KR100268855B1 (en) | Method for manufacturing low-temperature reheat oriented electrical steel sheet by one-time rolling annealing | |
| KR100240989B1 (en) | Manufacturing method of high magnetic flux density oriented electrical steel sheet | |
| KR100360096B1 (en) | The method of manufacturing grain oriented silicon steel by low heating | |
| KR20010055101A (en) | A method for manufacturing the high permeability grain-oriented electrical steel sheet with low core loss | |
| JPH0257125B2 (en) | ||
| JPH0562802B2 (en) |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| FZDE | Dead |