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Publication numberUS3650851 A
Publication typeGrant
Publication dateMar 21, 1972
Filing dateJul 7, 1969
Priority dateJul 17, 1968
Also published asDE1936425A1, DE1936425B2
Publication numberUS 3650851 A, US 3650851A, US-A-3650851, US3650851 A, US3650851A
InventorsBalazs Fulop, Hegedus Zoltan, Stefan Mihaly, Tapolcai Laszlo
Original AssigneeCsepel Muevek Femmueve
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Gallium containing cold-rolled transformer laminations and sheets with a cubic structure
US 3650851 A
Abstract
Cold-rolled transformer laminations with a cubic structure, containing a maximum of 4 percent by weight of silicon alloyed with 0.0001-0.20 percent by weight of gallium, 0-0.5 percent by weight of nickel and 0-0.5 percent by weight of copper.
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United States Patent Stefan et al.

[ 1 Mar. 21, 1972 GALLIUM CONTAINING COLD- ROLLED TRANSFORMER LAMINATIONS AND SHEETS WITH A CUBIC STRUCTURE Mihaly Stefan; Fulop Balazs; Zoltan Hegedus; Laszlo Tapolcai, all of Budapest, Hungary Inventors:

Assignee: Csepeli Femmu Filed: July 7, 1969 Appl. No.1 839,683

Foreign Application Priority Data References Cited UNITED STATES PATENTS 3,008,857 11/1961 Mobius ..148/111 3,239,332 3/1966 Goss ..75/l25 3,337,373 8/1967 Foster et a1.. ..148/31.55

FOREIGN PATENTS OR APPLICATIONS 651,295 10/1962 Canada ..148/1l0 713,034 8/1954 Great Britain ..148/1 1 1 1,372,975 8/1964 France ..148/110 Primary Examiner-L. Dewayne Rutledge Assistant ExaminerG. K. White Attorney-Young & Thompson [5 7] ABSTRACT Cold-rolled transformer laminations with a cubic structure, containing a maximum of 4 percent by weight of silicon alloyed with 0.0001O.2O percent by weight of gallium, 0-0.5 percent by weight of nickel and 0-0.5 percent by weight of copper.

4 Claims, No Drawings GALLIUM CONTAINING COLD-ROLLED TRANSFORMER LAMINATIONS AND SHEETS WITH A CUBIC STRUCTURE The invention concerns cold-rolled transformer laminations and sheets with a cubic texture. The invention further concerns a process for the manufacture thereof.

It is known that the appearancein 1935 of transformer laminations with a so-called Goss texture resulted in great advances in transformer construction. Such laminations can be magnetized most easily in the direction of rolling andtheir magnetic properties are particularly good in the direction of rolling. Thus e.g., the power loss V of a lamination of thickness 0.35 mm. is not more than 0.48 w./kg., while itsinduction B in a magnetic field of 25 AW/cm. equals 18,900 G. In the transverse direction, i.e., at right angles to the direction -of rolling, however, the magnetic properties are less advantageous: the power loss V is about 1.37 w./kg., whilst-B is only about 12,200 G. Due to the poor magnetic properties in the transverse direction, only those transformers can be manufactured from transformerlaminations with aGoss texture, wherein thedirection of the magnetic'linesof force coincide with the direction of rolling of the lamination (e.g.,.sectional lamination cores).

It is further known that both in cold-rolled, aswell as in hotrolled transformer laminations and sheets with isotropic'magnetic properties, the magnetic properties are only slightly different in the rolling and transverse directions but the optimum magnetic properties which may be achieved with these laminations, are greatly inferior to the corresponding properties of laminations with a Goss texture: the'power loss V is 0.8-l .5 w./kg., and the inductionwith a field intensity of 25 AW/cm. has a value of 14,500 G.

For exacting electrotechnical applications the magnetic properties of the isotropic laminations and sheets are not adequate; such requirements can only be met by transformer laminations with a cubic structure, which can most readily be magnetized in two directions, namelyin the direction of rolling and in the transverse direction in the plane of the sheet.

Transformer laminations with a cubic texture have various advantages, the following being the most important:

a. the magnetic properties are extremely advantageous: the power loss V is 04-06 w'./kg.- in the longitudinal, as well as in the transverse direction, the initial permeability is 1,500-5 ,000 G/Oe, and the maximum permeability reaches 25,00050,000 G/Oe;

the favorable magnetic properties are approximately equal in the longitudinal and transverse directions,which makes possible the manufacture of the various E-, U- and M-cores by simple methods;

c. by means of the cold-rolled transformer laminations with a cubic texture, magnetic properties can be achieved, which are equivalent to those of 45 percent iron-nickel alloys e. g., Permalloy B), whereby, however, the induction is far superior to the values obtainable with the.iron-- nickel alloys.

For a manufacture of laminations sheets with a cubic texture, the most important, known processes are given in the fol lowing:

a. an alloy containing 20-40 percent of Si or, instead of part of the Si-component, aluminum, and into which also 0.050.3 percent of manganeseand a small amount of nickel can be alloyed, is hot-rolled to a thickness of about 3.0 mm., then cold-rolled with three to five intermediate annealings to 0.04-0.20 mm., and finally thermally treated for a longer period (for at" least 24 hours) at 1,200-l,300 C. in a dry hydrogen atmosphere with a dew point below 50 C.;

. as is known, the cubic texture can be improved by arranging nickel alloys or nickel-containing ceramic materials near the surface of the lamination during the last thermal treatment;

. the formation'of the cubic texture can alsobe improved by carrying out the last two intermediate annealings between l,l and l,300 C.;

d. the cubic texture can advantageously be influenced while respecting certain requirements in that a small amount of hydrogen sulphide is added to the gas amount of hydrogen sulphide is added to the gas atmosphere in the course of the final thermal treatment;

as is known, it is possible to manufacture transformer laminations with .a cubic structure starting from a steel ingot crystallized directionally -by suitable methods, after -:an advantageously chosen hot-rolling, subsequent thermal treatment and cold-rolling performed with intermediate treatment, if during the final thermal treatment a dry hydrogen atmosphere or a vacuum is applied;

. for manufacturing lamination with a cubic texture, a finished,.Goss-textured lamination can be rolled further .in twosteps-with intermediate annealing, after which the final thermal treatment described under (a) is to be used;

. finally it is known to produce silicon-iron laminations with a cubic texture by means of the original direction of rolling-with respect to 45 or 90 rollers in the plane of the sheet.

All these known processes have the common disadvantage that they require a very strict-observation of the manufacturing technique. Even a small change in the rolling system (number of deformations, degree of the individual deformations) or in the intermediate annealing, or minor changes in the content of impurities of the alloy, influence the formation of the cubic'texture considerably. The fact that with the same particle orientation, different magnetic properties can occur is a further disadvantage of the known processes. Precisely for these reasons it is very difficult to manufacture transformer laminations with a cubic structure on an industrial scale.

.It is the object of the-invention to avoid the grave disadvantages of theknown methods and to provide a process by means of which transformer laminations can be mass produced in a simple manner and at low cost.

The invention is based on the following findings:

1. If a certainamount of gallium is added to the steel containing at most 4 percent by weight of Si, the magnetic properties of the iron-silicon alloys vary most advantageously, the cubic texture formation is considerably increased, the material becoming, however, less sensitive to variations in the rolling and thermal treatment techniques.

Of the numerous advantageous effects of alloying with gallium, the following may be mentioned:

' a.- the temperature of the primary recrystallization is varied;

.b. the number of particles in the cubic texture position, formed during the primary recrystallization is increased so that the secondary recrystallization can consequently be carried out at lower temperatures, whereby the particle size becomes more uniform. All this has an ad vantageous effect on the magnetic properties, and the quantity of cubic texture-oriented particles reaches 80-90 percent;

. due to the presence of the gallium traces dissolved in the metal, the crystal surface and crystal boundary energies are considerably varied during the final thermal treatment, i.e., these values are influenced favorably relative to the cubic texture formation;

. due to the change in duration of the final thermal treatment and, if desired, the use of the magnetic field during cooling, theadjustment of the ratios of the initial and maximum permeabilities of the laminations with a cubic structure is made possible within wide limits.

2. The action of the gallium alloy can be improved by adding certain quantities of one or more further metals (e.g., nickel or copper).

Both findings are surprising since hitherto it hasbeen assumed that for the manufacture of transformer laminations with a cubic structure it is preferable to keep the content of impurities and alloying materials of the iron-silicon alloys as low as possible and the presence of all alloying constituents,

3. In the case of gallium or of an alloy of gallium with further metals, the best way of avoiding sticking together of the windings and the oxidation or soiling of the lamination surface during the final thermal treatment is to interpose or insert a wire or strip, consisting of an iron alloy containing 0.5-6 percent by weight of aluminum.

The cold-rolled transformer laminations with a cubic texture according to the invention contain a maximum of 4 percent by weight of silicon, alloyed with 0.000l-0.20 percent by weight, preferably 0.04-0.06 percent by weight of gallium, 0.0.5 percent by weight, preferably 0.2-0.4 percent by weight of nickel, 0.5 percent by weight, preferably 02-03 percent by weight of copper.

The invention further concerns a method for the manufacture of such cold-rolled transformer laminations and sheets with a cubic texture, by micro-alloying the iron-silicon base material by successive thermal shaping, descaling, coldrolling, intermediate annealing, final rolling and final thermal treatment of the ingot obtained. According to the invention one proceeds in such a manner that the micro-alloying of the steel containing at most 4 percent by weight of silicon is effected with 0.000l0.20 percent by weight, preferably 0.04-0.06 percent by weight of gallium, 00.5 percent by weight, preferably 02-04 percent by weight of nickel and 0-0.5 percent by weight, preferably 02-03 percent by weight of copper and, if desired, prior to the final thermal treatment, during the winding up of laminations a wire or strip consisting of an iron alloy containing 0.5-6.0 percent by weight of aluminum is used as a separating means between the lamination windings or core parts.

Of the principal advantages of the process according to the invention, the following may be mentioned hereinbelow:

a. as against the known processes for the manufacture of laminations with a cubic structure, the process according to the invention is more simple and may be carried out with higher technological tolerances;

b. the initial and maximum permeabilities, coercive force and induction, as well as the power loss of the lamination with a cubic texture can be considerably improved;

0. about 80-90 percent of the particles are in the cubic texture position in the end product;

d. laminations as well as finished cores and parts can be subjected to the final thermal treatment;

e. the process can be carried out by using known apparatus for the manufacture of transformer laminations with a Goss texture.

Several examples for carrying out the process according to the invention are given in the following. Example l An iron-silicon alloy with a nominal content of 3.2 percent of silicon, 0.05 percent of gallium and 0.35 percent of nickel with a very small content of impurities, is produced in an induction vacuum furnace from a pure iron charge of good quality, from metallic silicon with a silicon content exceeding 98.5 percent and with an aluminum content of less than 0.5 percent, as well as from metallic nickel. The impurities of the alloy do not exceed the following values: 0.05 percent of carbon, 0.015 percent of sulphur, 0.03 percent of chromium, 0.03 percent of molybdenum, 0.93 percent of vanadium, 0.03 percent of tungsten, 0.01 percent of titanium and 0.005 percent of oxygen.

The ingot is hot-rolled to a thickness of 3 mm. at a starting temperature of l,l00-l,l50 C. The temperature of the lamination is kept above 900 C. before the last pass.

The scale is removed from the hot-rolled lamination by means of a pickling agent containing sulphuric acid and the lamination is then annealed for 2 hours at 800 C. in a humid hydrogen atmosphere with a dew point of +20 C. The lamination is then cold-rolled in several passes to a thickness of 0.80 mm. and, after degreasing, thermally treated for 2 hours at a temperature of 850 C. in a hydrogen atmosphere with a dew point of 30 C. The lamination is then cold-rolled in several passes to a thickness of 0.30 mm. and, after degreasing, thermally treated for 2 hours at a temperature of l,000 C. in a vacuum of 10 Torr.

The lamination, the surface of which is metallically pure, is cold-rolled with polished rollers in several passes to a thickness of 0. 10 mm. A ribbed strip made of steel containing 1.5 percent of aluminum having a clean surface, is inserted between the windings of the degreased lamination. The thus prepared lamination coil is subjected to a thermal treatment in a vacuum furnace in a vacuum of 10 Torr in such a way that during heating the material is kept hot for 2 hours between 550 and 700 C.; the temperature is then raised to l,l00 C. and kept for 20 hours at this value. After completing the thermal treatment, the charge together with the furnace is cooled to 500 C. percent of the particles of the lamination thus produced are in the cubic texture position; the initial permeability of the lamination is 4,200 G/Oe and the maximum permeability 45,000 G/Oe.

Example 2 A lamination cold-rolled according to Example 1 to 3 mm. and produced from a steel ingot, the composition of which corresponds to that of Example 1, is descaled in a pickling agent containing sulphuric acid and then subjected for 2 hours to thermal treatment at 800 C. in a humid hydrogen atmosphere with a dew point of 20 C. The lamination is then cold-rolled to L0 mm. in several passes and, after degreasing, thermally treated for 2 hours at a temperature of 850 C. in a hydrogen atmosphere with a dew point of30 C. The lamination is then cold-rolled in several passes to a thickness of 0.45 mm. and then-after degreasing-subjected for 2 hours to thermal treatment at a temperature of 1,000 C. in a vacuum of 10' Torr.

The lamination, the surface of which is metallically pure, is finally cold-rolled with polished rollers in several passes to a thickness of 0.20 mm. Thereafter one proceeds as in Example 1.

The initial permeability of the lamination thus produced is 4,100 G/Oe and the maximum permeability 37,000 G/Oe. Example 3 One proceeds as described in Example 1 but the silicon content ofthe alloy is adjusted to 2.6 percent by weight, the nickel content to 0.3 percent by weight and the gallium content to 0.05 percent by weight.

The initial permeability of the lamination thus obtained is 4,000 G/Oe and the maximum permeability 38,000 G/Oe. Example 4 One proceeds as described in Example 1 but the final thermal treatment is carried out for 5 hours.

The initial permeability p of the lamination thus obtained is 3,300 G/Oe and the maximum permeability 24,500 G/Oe. Example 5 One proceeds as described in Example I but the final thermal treatment is carried out in a dry hydrogen atmosphere (dew point below 50 C.) at l,200 C. in such a way that this temperature is maintained for 20 hours. In this manner a lamination is obtained, the initial permeability of which is 3,700 G/Oe and the maximum permeability 37,000 G/Oe. Example 6 One proceeds as described in Example 1 except that prior to the final thermal treatment the desired core sheets are cut out from the lamination, and the thermal treatment is carried out in such a way that during cooling and on reaching 700 C. the core sheets are exposed to the action of the magnetic field of a field intensity of 10-20 Oe. The initial permeability i of the maximum permeability 63,000 G/Oe.

We claim:

1. Cold-rolled transformer lamination with a cubic structure, consisting essentially of up to 4 percent by weight of silicon, 0.00l0.20 percent by weight of gallium, 00.5 percent by weight of nickel and 0-0.5 percent by weight of copper, balance essentially iron.

2. Cold-rolled transformer lamination as claimed in claim 1, in which said gallium is 0.040.06 percent by weight, said nickel is 02-04 percent by weight and said copper is 02-03 percent by weight.

3. Cold-rolled transformer lamination as claimed in claim 1, in which said silicon is about 3.2 percent by weight, said gallium is about 005 percent by weight and said nickel is about 0.35 percent by weight.

4. Cold-rolled transformer lamination as claimed in claim 1, 5 in which said silicon is about 2.6 percent by weight, said nickel is about 0.3 percent by weight and said gallium is about 0.05 percent by weight.

Patent Citations
Cited PatentFiling datePublication dateApplicantTitle
US3008857 *Feb 7, 1958Nov 14, 1961Ver Deutsche Metallwerke AgProcess for the production of grain oriented magnetizable strips and sheets
US3239332 *Mar 9, 1962Mar 8, 1966Fuji Iron & Steel Co LtdElectric alloy steel containing vanadium and copper
US3337373 *Aug 19, 1966Aug 22, 1967Westinghouse Electric CorpDoubly oriented cube-on-face magnetic sheet containing chromium
CA651295A *Oct 30, 1962Westinghouse Electric CorpProduction of thin goss oriented magnetic materials
FR1372975A * Title not available
GB713034A * Title not available
Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US4748000 *Apr 10, 1986May 31, 1988Sony CorporationSoft magnetic thin film
Classifications
U.S. Classification148/307, 148/111
International ClassificationC21D1/70, C22C38/02, H01F41/02, C21D1/68, C21D8/12, H01F1/12, H01F1/147, H01F27/24
Cooperative ClassificationH01F41/0206, C21D8/1283, H01F27/24, C21D1/70, C21D8/12, C22C38/02, H01F1/14775, C21D8/1233, C21D8/1272
European ClassificationC21D8/12, H01F41/02A, H01F1/147S1, C21D1/70, C22C38/02, H01F27/24