DE2712657A1 - Oriented boron-contg. silicon steel strip - obtd. by coating with insulating layer contg. boron and then heat-treating - Google Patents

Abstract

Oriented silicon steel strip is produced by (A) producing a silicon steel strip with a fine-grained primary recrystallisation structure contg. 2.2-4.5% Si, 1.5-50ppm B, 30-90ppm N2 in a ratio w.r.t. the B of 1-15pts. per pt. of B; (B) coating the strip with an electrically insulating, adhesive coating contg. 6-150 ppm B; and (C) heat-treating to develop a secondary recrystallisation structure, (110) 001 , in the strip. The amt. of B in the steel can thus be reduced without affecting the properties of the strip.

Description

Silicon iron sheet with the addition of boron and its process

Manufacturing Description The invention relates to generally to the production of electric steel and more in particular to a new one Process for the production of sheet metal made of silicon iron oriented in a Vs, pulling direction by using small amounts of boron in the electrically insulating coating on one boron-containing magnetic sheet made of silicon iron and through the use of small amounts of boron in the coating in a critical proportion to both boron and nitrogen content des @leches.

The sheets to which the present invention is directed will common trip referred to as electro silicon steels or more correctly silicon iron and they are usually composed mainly of iron, that of 2.2 - 4.5% silicon and relatively small amounts of various impurities and very small amounts of carbon are alloyed. These products are of the "cube-on-edge" type, with more than 70% of their crystal structure, expressed in Miller indices, in the (110) (001) texture are oriented.

Such grain-oriented sheet metal products made of silicon iron are currently being used technically produced by the sequence of steps of hot rolling, heat treating, cold rolling, Heat treatment, repeated cold rolling and a final heat treatment, to decarbonize, desulfurize and recrystallize the products.

Bars (ingots) are usually hot worked into a strip-like or sheet-like configuration less than about 4 in thickness mm brought, which rn n referred to as "hot-rolled strip". The hot-rolled tape wi £ d then using a suitable intermediate annealing cold to the finished sheet metal or Rolled strip thickness, usually with a 50% reduction in thickness, and the product is given a final or texture-producing annealing treatment.

US Pat. No. 3,905,842 states that the magnetic properties Such sheets can be improved considerably if boron is used in the metal so that it is there at the time of the final or texture developing glow is present in a critical proportion to the nitrogen content of the metal. As further stated in this US-PS, that is necessary to produce this result The amount of boron is very small, but critical to a large extent.

It is further stated in US Pat. No. 3,905,843 that the use of Boron in metal is in proportion to nitrogen, while one has the proportion of manganese to keep sulfur at less than 2.1, the corresponding considerable improvement the magnetic properties of a product made possible by dividing it into two Stage n cold rolling with intermediate annealing was obtained.

Subject of a US patent application with the serial no. Is 585.093 the new concept of cold rolling hot rolled sheet from silicon iron directly to the final thickness without an intermediate heat treatment by using less, but critical amounts of boron and by maintaining the ratio of manganese to sulfur in the metal less than 1.8.

Tn the present invention it has now been found that under certain Conditions the presence of boron in the usual electrically insulating coating on sheets of .silizum titan have a beneficial effect on secondary recrystallization of the metal to develop the (110) (001) texture and associated special may have magnetic properties. In particular it was found that the presence a very small amount of boron in the coating during the final annealing for development leads to considerably better magnetic properties than would otherwise be produced. This small amount of boron can actually cause secondary recrystallization to occur cause if it would not occur without the boron. However, it was determined that the presence of boron in the insulating coating during the final annealing is not effective in this regard, if at the beginning of the final After annealing, there is essentially no boron in the metal itself. Because of the present Invention, however, the amount of boron can be reduced considerably, according to the two the aforementioned patents and the patent application for the ladle is to be added without that thereby the desired properties of the finished sheet made of silicon iron, attributable to the presence of boron during the final glow, be affected.

It has also been found that beneficial results persist Can be obtained by putting the amount of boron in a cold rolled and decarburized Silicon iron sheet is limited to a specific area and you can use the amount of boron present in the electrically insulating coating on the sheet metal to one al ren area restricted. It was also found that to produce these results the total amount of boron in the alloy and in the coating thereon to a certain extent Is to be limited to the maximum value. It was also found that one can use proportion purely of the nitrogen content of the alloy in a special way compared to the middle ones and upper ranges of the total boron content of the alloy and its coating can obtain beneficial results regularly and routinely.

In particular, the secondary recrystallization has been found to be persistent can be obtained during the final annealing of the silicon iron, if this contains only 1.5 ppm boron and only 6 ppm in the electrically insulating coating Boron are available.

Much greater total amounts of boron in the alloy and its coating equally consistently leads to products with excellent magnetic properties provided that the total boron content does not exceed 90 ppm, and also provided that that the boron content of the alloy at the beginning of the final annealing is not 50 ppm exceeds. When the boron content of the alloy plus that available in the coating If boron exceeds 40 ppm, the nitrogen content of the alloy should be greater than 70 ppm and preferably in the range of 80-90 ppm for consistently good results his.3 regarding the magnetic properties of the n a preferred direction oriented magnetic sheet made of silicon iron.

It was further found that, with the exception of the extreme values of the above critical area of the boron present in the coating, increases in the boron content of the overhang to significant decreases in the losses of the finished sheet and to one lesser degree to an improvement in the excellent permeability of the product to lead. It was also found that the ratio of manganese to sulfur according to of the present invention can be up to 2.5 and consistently good Maintains magnetic properties of the end product.

The Findings Made In The Practice Of The Present Invention are surprising, especially considering the fact that they are very different Results are obtained when boron is added to the coating on a sheet of silicon iron, that does not contain boron is added for the final annealing. According to the US PS 3,676,227 reported such additions to secondary grains smaller than average lead, but give no improvement in permeability while following the present Invention does not reduce the grain size, but improves the permeability considerably will.

It was also found that the amount of boron in the coating required for Achieving the results of the invention is required, both critical is also quite low, but not difficult to adjust. The choice is yours between applying the boron along with the Mg (OH) 2 or other similar electrically insulating coating in the form of a slurry or the formation of the Coating according to US Pat. No. 3,054,732 with subsequent contacting of the coated Sheet metal with an aqueous solution of a boron compound. The latter procedure can be done either by dipping or by brushing or spraying the coating be carried out with the aqueous solution.

It was found that H3B03 and Na2b4l> 7 for the present Invention suitable boron sources are, and their application can either individually or be done in combination. Other boron sources can also be used, provided they are compatible with the final annealing to achieve the purpose of the present invention are used in the coating in addition to or as alternative connections. The basic requirement that the boron source in the coating must meet is that it decomposes under the conditions of the final annealing so that the boron in diffuse into the alloy surface and those with the present invention can bring about results and benefits to be achieved.

From the foregoing it can be seen that the present invention is capable of both has a process as well as a product aspect. The product according to the present Invention can be a fine-grain, primarily recrystallized magnetic sheet made of silicon iron with a final thickness that is a boron-containing coating from the reaction product of silicon and magnesium hydroxide or a similar compound. By the content of boron, nitrogen, manganese and heavy in the sheet and of boron in the coating the sheet made of silicon iron can be oriented in a preferred direction State in which it has the valuable magnetic properties has, but the sheet does not need to contain much of the boron that the development these properties during the final annealing by secondary recrystallization made possible.

Further, the product can be decarburized, coated, cold-rolled Be sheet of the final thickness, which boron in critical proportion to nitrogen in the Contains metal, and in combination with the boron in the coating, it enables development the desired magnetic properties through secondary recrystallization during of the final glow.

The process of making these new coated products from Silicon iron is as new as the overall process for making the desired one kornie @@ ierten sheet metal.

The sheet according to the present invention is an electrically insulated one Magnetic sheet made of fine-grain, primary recrystallized magnetic sheet made of silicon iron, containing 3 - 50 ppm boron and a thin, firmly adhering boron-containing coating from a water-insoluble hydroxide of calcium, magnesium, manganese or aluminum having. The amount of boron in the coating should preferably be between 25 and 150 ppm, based on the sheet of silicon iron, are, and to achieve optimal For results to limit core losses, the boron content should be between 50 and 80 ppm, also based on the sheet metal. These areas are independent on the boron content of the silicon iron sheet, as long as the boron content in this sheet is in the range of 3 to 50 ppm.

The sheet metal according to the invention can also be in the form of an electrically insulated one Magnetic sheet made of fine-grain, primary recrystallized magnetic silicon iron present, which contains 1.5 - 50 ppm boron and 30 - 90 ppm nitrogen and one has a firmly adhering metal hydroxide coating, which is insoluble in water, of 6 to Contains 90 ppm boron in such a ratio to the boron content of the alloy sheet, that the total amount of boron is between 7.5 and 90 ppm.

The inventive method includes the steps of creating this Sheet metal and to carry out the final heat treatment to develop the secondary recrystallization in it (cube-on-edge).

The invention will be followed with reference to the drawing explained in more detail. , l show individual: FIG. 1 a graphic representation in which the permeability is plotted against the boron content of the cold-rolled strip, where the three curves show the effects of the addition of boron. l z, m magnesia coating des Show stripes; Figure 2 is a graph showing the Improvement in the loss against boron content of the cold rolled strip is plotted, the curve showing the effect of brushing the magnesia coating shows with dilute boric acid solution before the final glow; Figure 3 a graph showing both permeability and losses against the maximum boron content available from the coating for the strip is applied are, with the three curves showing relatively little improvement in permeability as a function of increasing boron content in the coating and somewhat larger improvements show in terms of losses for the same boron area; Figure 4 is another graph in which the permeability versus the maximum boron content, available for the strip from the coating was applied, the four curves show the effect of the fold of the metal increasing from 42 to 84 ppm Show nitrogen and one of the curves also shows the effect of increasing from 9 to 50 ppm Show boron content of metal; FIG. 5 is a graph similar to FIG 4 for metal samples with a 40% higher sulfur content and FIG 6 is a graph similar to that of FIGS. 4 and 5, the curves Data show obtained in testing metal treated in accordance with the present invention which has an even greater sulfur content.

In practicing the present invention, one can use the above Manufacture sheet metal by making a silicon iron melt of the required composition prepared, pour this and roll it hot to an intermediate layer. The melt can at Pour 2.2 - 4.5% silicon, manganese and sulfur in such Contain quantities that the ratio of manganese to sulfur is less than 2.3, and the melt can further contain 3 to 50 ppm boron and 15 to 95 ppm nitrogen in the ratio range to boron contain from 1 to 15 parts to 1, and the remainder of the melt is iron and small amounts of incidental impurities that include carbon, aluminum, copper and include oxygen. The melt can also be 2.2 - 4.5 S when pouring Silicon, 1.5 to 50 ppm boron and 30-90 ppm nitrogen in the ratio range to Contains boron from 1 to 15 parts to 1, further manganese up to 0.1% and sulfur up to at a ratio of 2.5 parts manganese and per part sulfur, the remainder Iron oil are small amounts of the above incidental impurities. In each After annealing, the trap becomes the final thickness with or without intermediate annealing cold rolled and then decarburized.

The fine-grained, primary recrystallized sheet of silicon iron obtained will be processed further to create regardless of the way in which it was made according to the present invention essential boron-containing coating for the glow developing the final texture. The plating is preferably carried out electrolytically carried out as described in US Pat. No. 3,054,732, with a coating in a thickness from 0.005 to 0.013 mm of Mg (On) 2 is applied to the sheet. The so overdone Sheet is then immersed in an aqueous solution of boric acid or sodium borate or a immersed in another suitable boron compound, which is preferably relatively dilute and contains in the order of 5 - 10 g of the boron compound per liter.

As the final stage of the process according to the invention, the sheet metal so coated in hydrogen or a mixture of nitrogen and hydrogen heated to cause secondary grain growth which starts at around 950 ° C. By increasing the temperature at a rate of about 50 ° C per hour the recrystallization process is completed at 1000 ° C., with heating also @ s to 1175 ° C can take place in order to completely remove the remaining carbon, To ensure sulfur and nitrogen.

The invention is explained in more detail below with the aid of examples.

Example 1 Silicon iron strips of the following composition were prepared according to the process described in U.S. Patent 3,905,843 referenced above: Carbon 0.030% manganese 0.035% sulfur 0> 031% boron 0.0010% nitrogen 0.0050 % Copper 0.24% aluminum 0.005% iron remainder Series of hot rolling passes followed by pickling and annealing of the sheets with a Intermediate thickness (about 2.5 mm), about 0.27 and about 0.34 mi thick sheets made. The cold rolling was after reaching the intermediate thickness to a thickness of about 1.5 mm and then the material is reheated and cold-rolled to the final thickness, whereupon the cold-rolled sheet at a temperature of 800 ° C for 8 minutes in Hydrogen (room temperature dew point) has been decarburized.

Epstein strips were cut from the metal sheets and tied with a about 0.005 mm thick coating of Mg (OH) 2 according to the method of US Pat. No. 3,054,732, in particular Example II.

Three of each of the strips with a thickness of about 0.27 and about 0.34 mm became to Tests selected for the method of the invention, one strip of each group used as a control sample and therefore not provided with boron in the magnesium oxide coating became. Another strip from each group was placed in a 5 g Sodium borate per liter containing solution immersed while the third strip of each group immersed in a solution containing 10 g of sodium borate per liter for 15 seconds became. The six strips were then annealed in hydrogen at 1160 ° C. for 5 hours. The magnetic properties of the strips obtained are as follows Table I summarized.

Table I Na2B407 immersion solution mWatk / 454 g (coated) u at IOH Sample (g / l) 15 kG 17 kG (coated) 11-lH 0 0 598 898 1799 11-lH 5 5 687 9t2 1806 11-lH 10 10 594 840 1881 14-iH 0 0 710 1050 1743 14-1H 5 5 864 1240 1707 14-1H 10 10 740 1040 1801 11-lB 0 0 661 1000 1729 11-lB 5 5 646 908 1834 11-1S 10 10 uu3 992 1747 14-1B 0 0 665 988 1767 14-1B 5 5 725 1060 1797 14-1B 10 10 760 1084 1778 Example II Two Epstein packs of additional strips of about 0.2675 and sheets about 0.2695 mm thick were produced as described in Example 11 and electrolytically coated and then 15 seconds in a 7.5 g Na2B407 per liter containing aqueous solution immersed. The Epstein packs of the Strips were subjected to the final annealing according to Example I and thereby obtained the following results summarized in Table II.

Table II mWatt / 454 g pack 15 at kG 163 kG 17 kG p at ion 1H 584 714 808 1842 Lab annealing 1H 581 715 807 1834 Lab annealing Example III With a Another attempt to carry out the process according to the invention was a commercially available one Melt prepared using the BOF silicon iron as described in US Pat. No. 3 905 843, the composition of which in the ladle was as follows: silicon 3.10% copper 0.26% manganese 0.032% sulfur 0.014% carbon 0.024% boron 0.0015 % Nitrogen 0.0035% hot rolling and direct cold rolling to final thickness of about 0.275 mm was carried out as described in US patent application Ser. 749,117 described, whose priority is claimed for the present application. The cold rolled Material has been decarbonized and covered with a MgO coating, as in U.S. Patent 3 054 732, and then immersed in a solution consisting of 540 l of water, 6820 g of boric acid and 1.9 l of ammonia consisted.

50 ppm boron (steel equivalent) was added to the magnesium oxide coating built-in.

The resulting coated strips were then in dry Hydrogen annealed for 3 hours at about 1175 ° C.

The test specimens obtained had good magnetic properties, wherein the permeability in a 10 oersted field was 1905 Gauss per oersted and the losses were 0.468 and 0.629 watts per 454 g at 15000 and 17000 Gauss, respectively.

Example IV In another test, an operating batch such as described above, prepared in the ladle with the following composition: Silicon 3.15% copper 0.26% manganese 0.32% sulfur 0.14% carbon 0.26% phosphorus 0.005% chromium 0.06% Mn / S = 2.29 nickel 0.091% titanium 0.004% tin 0.011% boron 0.0011 % Nitrogen 0.0035% iron remainder The hot and direct cold rolling to the final thickness of u 0.265 mm was again as in the US patent application Serial No. 749,117 executed.

This material was then normalized and electrolytic provided with a 0.005 mm thick MgO coating, as described in US Pat. No. 3,054,732, and immersed in 1% boric acid solution during operation, as described in Example III.

Samples of Epstein packs of several coils were taken in a laboratory again immersed in 1% boric acid solution. Two more samples from each coil were taken immersed again in a 2% or 3% boric acid solution in the laboratory. During the analysis, the boron contents listed in Table III below were used determined in the coatings. In this Table III are also the magnetic properties summarized, those after 3 hours of annealing in dry hydrogen on the Epstein packings were measured.

Table III Loss at 17 kG coating boron + Lo in mWatt / 454 g p IOH mg / strip 1 Final normalize 656 1876 -O-Dipping 692 1872 0.68 1 s 674 1909 1.24 2 ß 707 1885 1.72 3% 705 1887 2.20 2 Final normalization 670 1886 -O-industrial diving 640 1900 1.57 1% 649 1912 2.06 2% 659 1921 2.86 3 % 711 1906 2.88 3 Final normalization 656 1870 -O-operational diving 643 1886 o.89 1 s 653 1909 1.33 2 s 658 1907 2.13 3% 688 1886 2.50 1 mg / Epstein strip = 50 ppm SiFe equivalent Example V There were in an air induction furnace under Argon protective layer made of electrolytic iron and 98% ferrosilicon, twelve laboratory batches melted, all of which contained 3.1% silicon, 0.1% copper and 0.03% chromium. The same amount of sulfur (0.024%) was added to each batch as @isensulfid added, with the sulfur analysis values from 0.033% up to 0.019 % with an average value of 0.026%.

Ingots were cast from these melts and disks from these Cut to a thickness of about 4.3 cm and cut at 1200 ° C in six passes hot rolled to a thickness of about 2.25 mm. After pickling they were out a hot tape heat-treated samples at 950 ° C, the time being for this between 930 and 950 ° C. was about 3 minutes. The hot strips were then rolled directly to a thickness of 0.27 mm cold, and the analysis results of these strips are summarized in Table IV below.

Table IV Composition as determined on cold rolled strips Batch ppm tI ppm N ppm 0 X Mn% S% C 1 <1 68 70 0.034 0.025 0.038 1.2 - - 0.036 0.033 0.037 3 1.6; 1.4 - - 0.035 0.025 0.038 4 1.8 - - 0.034 0.019 0.040 5 2,4,3,1 49 76 0.035 0.029 0.033 6 5.6 48 90 0.0 @ 5 0.025 0.044 7 6.9 46 88 0.036 0. \ .30 0.037 8 7.4 52 115 0.036 0.021 0.039 9 14 50 98 0.035 0.031 0.036 10 24 46 96 0.036 0.024 0.038 11 26.25 62 70 0.036 0.022 0.040 12 29 47 69 0.035 0.023 0.038 Epstein size strips of the cold rolled material were cut up to about 0.007 s by heating to 800 ° C in hydrogen with a dew point of about 21 ° C decarburized. The decarburized strips were coated with magnesia milk until to a weight gain of about 40 mg per strip, and to some of the magnesia-coated ones Strips were given boron additives using either a 0.5 or 1% strength Boric acid solution that is sufficient Left boron on the coating, that with complete absorption of this boron by the silicon iron, the boron content of the metal would be increased by 15 or 30 ppm. The coated strips obtained, those coated with boric acid solution as well as those not coated with it was subjected to the final annealing that was done in one heating from 800 - 1175 ° C in dry hydrogen at a rate of 40 ° C per Hour and then holding at the latter temperature for 3 hours duration.

The magnetic properties of the obtained. educts of the aforementioned Methods according to the present invention are as well as those of the control samples summarized in Table V below and in FIGS. 1 and 2.

Table V Magnetic properties after the final anneal in hydrogen only MgO MgO + 15 ppm B MgO + 30 ppm B batch ppm B 17 @B µ10H 17 kB p1OH 17 kB plOH 1 '1 - 1383 - 1402 - 1394 2 1.2 - 1432 1322 1483 - 1467 3 1.5 1136 1664 730 1873 1000 1678 4 1.8 929 1751 739 1876 1094 1655 5 2.7 771 1849 725 i881 940 1730 6 5.6 750 1887 - - 741 1856 7 6.9 696 1892 678 1908 8 7.4 749 1890 702 1898 755 1845 9 14 747 1891 701 1900 870 1768 10 24 813 1844 736 1869 1322 1536 11 26 754 1873 090 1900 8, '1805 1a 29 - 1472 - 1423 - 1406 Di @belle V and FIG. 1 shows the effect of boron additions to the coating on permeability. Boron in the coating in an amount which is 15 ppm theoretically available for the alloy Total boron corresponds, strongly promotes the magnetic properties, in particular of the alloys, which are only 1.5 or 1.8 ppm Contained boron. If the boron content of the coating is doubled, the permeability is reduced of the product. The deterioration in the permeability of strips with high boron content could be attributed to an imbalance in the boron-nitrogen ratio as is shown by the very different results obtained with the batch No. 11 high nitrogen content were achieved.

Curve A of Figure 1 shows the results obtained with samples whose magnesium oxide tracts were not treated with boron solution while curves B and C of Figure 1 represent the data obtained with samples, whose magnesium oxide coatings were treated with a boron-containing solution, which was 15 resp. 30 ppm total boron based on the alloy provided.

The improvement in hysteresis loss that the Bors added to the Coating is shown in FIG. The big improvement for both of them Alloys with the lowest boron content is mainly due to the improved permeability while improving by 50 milliwatts per 454 g of the alloys with higher boron content with little or no change in permeability is typical behavior for both laboratory and plant batches.

Example VI In another attempt to examine the possibilities The new process was a commercial melt using BOF silicon iron prepared as described in US Pat. No. 3,905,843, the analysis of the melt in the ladle brought the following results: silicon 3.10 S copper 0.29 % Manganese 0.033% Sulfur 3.019% Carbon 0.024% Boron 0.0015% Nitrogen 0.0058 % The cold-rolled and decarburized sheet was used for production Cut strips of Epstein packs, some of these strips with a Magnesium oxide coating were provided as described in Example V, and then with Boric acid solution was coated to narrow various borate levels from 10 to 90 ppm to convey, as illustrated in Figure 3. Other samples of the strips were made coated with magnesium oxide into which boric acid was mixed in in varying amounts available boron in the range of 10 to 70 ppm, as shown in the drawing shown. From these prepared samples and others coated, but not samples with boron added, Epstein packs were produced and used for the final anneal at 800 ° C and placed in the retort at one rate of 40 ° i) heated to the maximum temperature of 1175 0 per hour, which for 4 hours was held. The test pieces thus obtained were subjected to magnetic examinations subjected, the results of which are summarized in FIG. In addition, the Grain size of a number of the test specimens measured. The grain size of the control sample, in the coating of which no boron was available for the silicon iron was 9.8 mm, while the grain size of the sample with 15 ppm or in the coating was 11.3 mm and that of the test specimen with 30 ppm boron in the coating 10.4 mm and that of the sample with u0 ppm boron in the coating 11.5 mm mm was. The latter data is in contrast to what is in the prior Technique is described, according to which a reduction in grain size from 12 to 4 mm is said to result in a reduction in loss of about 50 milliwatts per 454 grams.

From FIG. 3 it can be seen that the boron additions to the coating on the silicon iron containing boron lead to a significant reduction in losses and a somewhat smaller change in permeability, i.e. H. to relatively slight increases in permeability over the range of 5 to 10 ppm to 90 ppm boron available for the silicon iron from the coating.

Example VII In another experiment similar to that of the example V were 11 laboratory batches in an air induction pot either under one Argon protective layer or with argon blown through the melt prior to casting or prepared with nitrogen according to one or both of the aforementioned protection classes. the Using argon alone resulted in the lowest nitrogen levels in the batches, and the use of nitrogen alone resulted in the highest nitrogen levels in the batches. The batches all contained 3.1% silicon, 0.1% copper, and 0.03 % Chromium.

The cold rolled strips of each of the batches described in Example I had the compositions listed in Table VI below.

Table VI Batch Composition as determined on Cold Rolled Strips Lot% Mn% S% C ppm B ppm N 20 0.025 0.011 0.036 7.8 42 21 0.027 0.010 0.035 6.2 48 22 0.025 0.010 0.033 9.2 84 30 0.025 0.10 0.033 51.0 84 23 0.027 0.013 0.036 6.7 43 24 0.025 0.014 0.029 7.2 55 25 0.025 0.013 0.030 7.7 62 26 0.025 0.013 0.030 8.2 72 27 0.024 0.017 0.030 6.3 42 28 0.024 0.018 0.032 5.9 60 29 0.025 0.019 0> 031 6.7 93 strips of Epstein cast from the cold rolled materials were made at 800 ° C in hydrogen with a dew point of e via 21 ° C down to less than 0.01 % Carbon decarburized. The strips were then coated with magnesium oxide milk, until they showed a weight gain of about 40 mg per strip, and then gave boron additives are added to a number of the strip coatings, by doing boron solutions at concentrations in multiples of 0.5% were used. Analysis of the Coatings on the boron content before the final firing showed that the concentration linearly increased by 12 ppm boron, based on the strip and not on the coating weight, for every 0.5% increase in the concentration of boric acid in the solution. The final one Annealing consisted of heating from 800 to 1175 ° C. at a rate of 40 OC per hour and hold at the latter temperature for 3 hours.

The permeabilities of the Epstein packings, with or without the addition of boron had been annealed to the strip coatings are shown in Figures 4, 5 and 6, where the batches are grouped according to the sulfur content. The nitrogen levels the strip before the final anneal is also indicated on the drawings. In Figures 4-6, the measured losses are adjacent to a number of more suitable ones Data points inserted.

All batches had improved properties due to the boron additions for coating, with the greatest improvement in the low-sulfur batch and high nitrogen content occurred.

With no addition of boron to the coating, all four lots experienced little Sulfur content a normal grain growth, with addition of boron to the coating takes place at complete secondary recrystallization of the high nitrogen batch. The tendency of the high nitrogen batches to develop high permeabilities, is also evident for the batches with medium sulfur content, the batch being with the lowest nitrogen content is worse than any other in this group.

It has also been observed that adverse effects such as blisters or Rolled chips, usually with relatively high nitrogen contents in silicon iron composite; sii.d, did not occur in the samples of this experiment.

In this description and in the claims as well as in the drawings is the boron content of the coating expressed as the total amount that theoretically for the one wearing the coatings Silicon iron strips available is. In practice, a small proportion of this boron is used during the final Annealing and before the completion of the secondary recrystallization in the strip diffuse. Depending on the circumstances, this fraction can be. is about half of the boron content in coatings with a low boron content.

L e r s e i t e

Claims (21)

Claims 1. A method for producing grain-oriented sheet metal Made of silicon iron, not shown in the following stages: A) Creation a fine-grain, primarily recrystallized sheet of silicon iron, the 2.2 contains up to 4.5% silicon, 1.5 to 50 ppm boron and 30 to 90 ppm nitrogen, wherein the ratio of nitrogen to boron in the range of 1-15 parts per part boron betlågt, B) Covering the sheet with an adhesive, electrically insulating coating, which contains 6-150 ppm boron, based on the silicon iron sheet, and C) subject the coated sheet undergoes a final heat treatment in order to result in the sheet Silicon iron to develop a secondary (100) E001) recrystallization texture. 2. The method according to claim 1, d a d u r c h g e k e n n -z e i c h n e t that the total amount of cies boron in the sheet metal and in the coating necessary for the sheet metal available is between 7.5 and 90 ppm. Method according to claim 2, d u r c h g e k e n n -z e i c h n e t, since the boron content of the silicon iron sheet is 1.5 ppm and the coating 15 ppm tor, based on the sheet of silicon iron. 4. The method according to claim 2, d a d u r c h g e k e n n -z e i c h n e t that the boron content of the sheet made of silicon iron is 6.9 ppm and the Coating 15 p all contains boron, based on the silicon iron sheet. 5. The method according to claim 2, d a d u r c h g e k e n n -z e i c h n e t that the silicon iron sheet contains 10 ppm boron and 30 ppm nitrogen and the coating contains 10-70 ppm boron based on the silicon iron sheet. 6. The method according to claim 2, d a d u r c h g e k e n n -z e i c h n e t that the sheet of silicon iron contains 50 ppm boron and 80-90 ppm nitrogen and the coating contains 10 to 40 ppm boron based on the silicon iron sheet. 7. The method according to claim 2, d a d u r c h g e k e n n -e e i c h n e t that the sheet of silicon iron manganese and sulfur in a ratio of up to contains up to 2.5 parts manganese per part sulfur. 8. The method according to claim 1 or 2, d a d u r c h g e k e n n z e i c h e t that the boron is present in the coating in the form of boric acid. 9 The method according to claim 1 or 2, d a d u r c h g e n n z e i c h e t that the boron is present in the coating in the form of matrix borate. 10. The method according to claim 1 or 2, further g e k e n n -z e i c h e n e t h e steps of electrolytically forming an electrically insulating Upper pull on the sheet and subsequent Ir., Bringing the coated sheet into contact with an aqueous solution, a boron compound. 11. The method according to claim 1 or 2, d a d u r c h g e k e n n z E i c h e t that the sheet of silicon iron is provided with the boron-containing coating by first coating the tray with magnesia milk and then the Magnesium oxide powder obtained: ug brushed with an aqueous boric acid solution. 12. The method according to claim 10, d a d u r c h g e k e n n -z e i c Note that the aqueous solution contains 5 g Nu2B07 per liter. 13. The method according to claim 10, d a d u r c h g e k e n n -z e c h n e t that the aqueous solution contains 10 g Na2B407 per liter. 14. The method according to claim 10, d a d u r c h g e k e n n -z e i c Note that the boron compound is boric acid and the solution is between 1 and 15 g of this acid contains ro liters. 15. The method according to claim 1, d a d u r c h g e h e n n -z e i c n n e t that the boron content of the coating is equivalent to 50 to 80 ppm based on the sheet of silicon iron. 16. Electrically insulated magnetic sheet material, g e k e n n -z e i A fine-grained, primarily recrystallized, magnetic sheet metal made of silicon iron, which contains 2.2 - 4.5% silicon, 1.5 - 50 ppm boron and 30 - 90 ppm nitrogen . and a boron-containing coating of a water-insoluble hydroxide the metals calcium, magnesium, manganese and aluminum. 17. Magnetic sheet according to claim 16, d a d u r c h g e k e n n -z e i c. * n e @ that the coating 6 - 90 ppm boron, based on the sheet of silicon iron, contains, and the boron content of the coating with respect to the boron content of the sheet is proportioned so that the total amount of the boron in the sheet and the boron in the coating is between 7.5 and 90 ppm. 18. Sheet according to claim 16, d a d u r c h g e k e n n -z e i c h n e t that the coating is an electrolytically applied Mg (OH) 2 coating that Silicon iron sheet contains 10 ppm boron and 30 ppm nitrogen and the coating Contains 50 - 80 ppm boron, based on the silicon iron sheet. 19. Sheet metal according to claim 17, d a d u r c h g e k e n n -z e i c, n e t that the boron content is 1.5 ppm and the nitrogen content is less than 55 ppm and the coating is electrodeposited magnesium hydroxide which is 15 ppm Contains boron, based on the silicon iron sheet. 20. Sheet according to claim 17, d a d u r c h g e k e n n -z e i c h n e t that the total boron content of the silicon iron sheet and that in the coating available Bnrs is between 6.5 and 90 ppm and the nitrogen content of the metal is between 80 and 90 ppm. 21. Sheet according to claim 17, d a d u r c h g e k e n n -z e i c h n e t that it contains 50 ppm boron and 80-90 ppm nitrogen and the coating between 10 and 40 ppm boron, based on the sheet of silicon iron. Contains.