CS218577B2 - Method of making the foil of the silicon steel with oriented grains - Google Patents

Abstract

Grain-oriented silicon-iron sheet containing 2.2-4.5% Si, 3-35 p.p.m. B, 30-75 p.pm. N (N:B in the range 1:1 to 15:1), 0.02-0.05% Mn, 0.005-0.025% S is improved by the incorporation of 0.01-0.1% of Sn and/or Sb. Magnetic properties are improved and weld brittleness reduced.

Description

The present invention relates to a process for producing grain oriented silicon steel.

The silicon steel produced according to the invention is commonly referred to in the art as "Electric" silicon steel and usually consists mainly of an iron alloy with about 2.2 to 4.5% silicon and relatively smaller amounts of various impurities with very small amounts of carbon. These steels have a so-called "cube at the edge" structure, since more than 70 percent of their crystal structure has an orientation (100) [001] when designated by Miller indices.

Such grain oriented silicon steel products are commonly produced by a sequence of hot rolling, heat treatment, cold rolling, heat treatment, cold rolling and then final heat treatment for decarburization, desulfurization and recrystallization. The ingots are preferably heat treated into a strip or sheet having a thickness of less than 3.81 mm, referred to as a "hot-rolled strip". The hot-rolled strip is then cold rolled with a suitable interleaving onto the finished sheet or strip of the desired thickness, which usually means at least a 50% reduction in thickness, and a final tempering is performed which produces the desired composition.

In these boron and nitrogen-containing silicon steels, the severe limitation of normal grain growth and hence the enhancement of secondary recrystallization to the precise grain orientation (100) [001] results from controlling the ranges of said components. The sulfur that is effective for this purpose is that which is not combined with sulfide-forming elements such as manganese, which is now an inevitable impurity in iron and steel. Therefore, the total sulfur content is necessarily greater than that required to achieve its grain growth inhibiting effect.

It is also well known in the art that the presence of a high total sulfur content and a small amount of boron can lead to appreciable brittleness in the welds performed in a silicon steel alloy. Due to this brittleness of the weld, it was practically impossible to weld together two hot rolled coils for cold rolling, which would be a desirable work practice, since reducing the sulfur content for this would result in a deterioration in the magnetic properties of the metal. This choice usually means that the advantage of good weldability is avoided.

The present invention has found that in certain boron and nitrogen containing silicon steel batches, the sulfur content requirement can be met to inhibit grain growth to a greater or lesser degree by using tin or antimo218577 nu. Furthermore, it has been found that tin additives do not increase the brittleness of welding for this purpose and that the magnetic properties are superior to those with higher sulfur contents without tin or antimony. In other words, it has been found how using tin or antimony can produce melts with magnetic properties that are superior to those with a high sulfur content and with the desired welding properties associated with a low sulfur content.

In particular, it has been found that the above new results can be consistently achieved by adding up to 0.01 percent tin or antimony to alloys containing only 0.010 percent sulfur, with the amount of tin or antimony required more than the lower sulfur content.

Furthermore, the inventor. It has been found that the magnetic properties can be further enhanced in silicon steel, namely in silicon steel to which tin or antimony has been added by applying a boron-containing coating to the cold rolled silicon steel sheet before the final heat treatment.

Similarly, it has been found that the temperature of the initial hot rolling has a noticeable effect on the permeability - in these - silicon - alloys - and iron, i.e. the silicon steel, which has the addition of tin or -antimone. Consequently, hot rolled strips having the above-mentioned composition at a temperature of 1200 to 1300 ° C have consistently higher permeability than hot rolled strips at a temperature of 1100 to 1150 ° C.

The process according to the invention therefore consists in that a silicon steel melt containing 2.2 to 4.5 wt. % silicon, 0.003 to 0.0035 wt. % Boron, 0.003 to 0.0075. - wt. - nitrogen. wherein the boron - and - nitrogen ratio is 1 to -. 0.02 to 0.05 wt. ° / o manganese,. 0.005 - to. .0,025 wt. % Sulfur and tin or - antimony - in amounts of - 0.01 to 0.1 wt. - the content of nitrogen, boron, manganese, sulfur and - tin or antimony at the maximum levels indicated - less than 0,2% of the melt, the remainder - iron, cast, ingot - is rolled to: of heat to an elongate body, for example a film, which is then - cold rolled into sheet or film - of a predetermined thickness, and the resulting cold rolled film is decarburized by final heat treatment and recrystallized to a secondary structure (100) [001].

According to a preferred embodiment of the invention, a silicon steel-electrically insulating additional coating containing 0.0015 wt. % boron based on the weight of the silicon-steel strip.

In the practice of the invention, the above-described cold-rolled sheet or strip product is obtained by preparing a melt of silicon steel or silicon and iron of the desired composition, then cast and hot rolled to an intermediate thickness. Thus, the casting melt will contain 2.2 to 4.5 percent silicon, about 3 to 35 milligrams of boron, and about 30 to 100 milligrams of nitrogen, ranging from one to 15 parts per one, and a manganese from 0.02 to 0 % And sulfur and tin or antimony in the above ranges, the remainder being iron and small amounts of random impurities. After tempering, the hot strip is cold rolled with or without intermediate tempering to the final desired thickness and then decarburized.

The resulting fine-grained, primarily-recrystallized silicon steel strip or cylindrical product, whatever the method of manufacture, is coated with magnesium for tempering to develop the final structure. The coating is preferably carried out electrolytically, as described in U.S. Pat. No. 3,054,732, whereby a uniform MgfOH coating of about 0.127 mm thickness is applied to the web. Boron may be included in the resulting coating in an amount and for the above, by immersing the coated strips in an aqueous boric acid solution - or the like.

As a final step in the process of the invention, the coated sheet is heated in hydrogen to induce secondary grain growth starting at about 950 ° C. When the temperature is increased at a rate of about 50 ° C per hour to 1000 ° C, the recrystallization process is complete and, optionally, heating up to 1175 ° C can be performed to ensure complete removal of residual carbon, sulfur and nitrogen.

Several preferred embodiments of the melt composition of the present invention will now be described.

Preferably, the melt comprises about 0.02-5 wt. % manganese, the sulfur content of the melt, is about 0.012 mass; % and - tin content in the melt is between about - 0.010. and 0.050 wt. - ° / o.

It is also advantageous if the melt contains between - about - 0.02 -. to 0.03 wt. % Manganese, between about 0.009 - and - 0.014 - wt. Between about 0.0.20 and 0.050 wt%; % tin.

In addition - can be expedient when. . .melt. it contains - between -as - -0.030 - and 0.040 masses, percent manganese, - between about. . 0.013 and - 0.019 wt. % sulfur and between about 0.020 and 0.050 wt.% tin.

It has been shown that the melt may contain about 0.024 wt. % manganese, about 0.008 wt.% sulfur, and about 0.097 wt. % tin, whereby. as a preparation for the final heat treatment of a cold rolled silicon steel strip, an electrically insulating adhesive coating containing about 0.0015 wt. % Boron based on the weight of the silicon steel strip.

Another amount is that the melt contains antimony and the nitrogen content is between 0.003 and 0.010 wt. % in a ratio of one to 15 parts per part of boron.

An expedient embodiment also depends on the amount of manganese in the melt being about 0.024 wt. The amount of sulfur in the melt is at most about 0.008 wt. And the amount of -antimone in the melt is at least about 0.04 wt. %.

The manganese content of the melt may also be about 0.04 wt. %, wherein the amount of sulfur in the melt is at most about 0.011 wt. and the amount of antimony in the melt is at least about 0.04 wt. ° / o.

As a preparation for heat treatment E, the decarburized film is provided with an electrically insulating adhesive coating comprising from about 0.0012 to about 0.006 wt. % boron based on the weight of the film.

It is also possible for the decarburized film to be provided with an electrically insulating adhesive coating containing at least 0.0012 wt. % boron based on the weight of the film.

A further possibility is to provide the decarburized film with an electrically insulating adhesive coating containing at least 0.0012% by weight of boron based on the weight of the film as a preparation for heat treatment.

The following illustrative, but non-limiting, examples of the novel process of the invention, as actually performed to achieve the above new results, are intended to provide one skilled in the art with information about the nature and particular utility of the invention.

Example 1

Four laboratory melts were melted in an air induction furnace under an argon hood using electrolytic iron and 98 percent ferro-silicon, containing a total of 3.1 percent silicon, 0.25 percent manganese, 0.012 percent sulfur, 5 to 10 million boron, 45 to 75 million nitrogen, 0.10 percent copper and 0.035 percent chromium. The tin was added in different amounts to separate melts to achieve a tin content range of 0.002 to 0.04 percent. The compositions of these melts according to the analysis are shown in Table I.

TABLE I

Tavba % Qty o / o S Mn / S O / o Sn ppm N 1 0,025 0.012 2,0 0,002 69 í 2 0.024 0.012 2,0 0.010 74 3 0,026 0.012 2.1 0.020 46 4 0,025 0.011 2.3 0,045 49

Cuts of 4.445 cm thickness were cut from ingots cast from these melt and hot rolled at 1250 ^° C in six punches to a thickness of approximately 2.286 mm.

After pickling, the hot strip samples were heat treated at 950 ° C, with a time between 930 and 950 ° C being about three minutes. The hot strips were then cold rolled directly to a final thickness of about 2.283 mm. Strips of cold-rolled material having an Epstein-size were decarburized to less than 0.06 percent by heating for two minutes at 800 ° C in hydrogen with a dew point of 20 ° C. At 0.10 percent tin, the carbon level after the decarburization heat treatment is approximately 0.010 percent. This leads to higher losses but does not affect permeability. Lower carbon levels and lower losses can be achieved by using a tempering atmosphere with a higher dew point. The decarburized strips were brushed with magnesium milk up to a weight gain of approximately 40 milligrams per stripe and boron was added to some strips coated with magnesium using a 0.5 percent boric acid solution, which deposited enough boron on the coating such that the metal boron content would increase by 12 millionths. The resulting coated strips, including both boric acid-brushed strips and strips that had not been treated, were subjected to a final tempering, which involved heating at 40 ° C per hour from 800 ° C to 1175 ° C in dry hydrogen and in keeping at this temperature for three hours.

The effects of tin on permeability and losses at 60 Hertz at 17.10 @ ¹ T are shown in the diagram in Figure 1, where the permeability at (10,000/4 π) Aur ^{1 is} plotted against% tin in the melt. with boron-containing coating, while curve V represents boron-free coated samples Losses in milliwats per 0.454 kg are plotted adjacent to the corresponding points on each curve. With these alloys a 0.020 percent perfect result is achieved in the presence of tin.

Example 2

In another experiment similar to Example 1, two laboratory melts were melted in an air induction furnace using an electrolytic iron and 98 percent ferro-silicon, both containing 3.1 percent silicon, 10 million boron and 40 to 50 million nitrogen, and otherwise had the composition shown in Table II.

TABLE II

Melting% Μη% S% C% Sn

0,028

0,026

The process from the melt stage to the finally tempered state should be avoided. same as in Example 1 except that hot rolling was performed at five different temperatures and the boron content of the coatings was greater because it was equivalent to 15 millionths based on the silicon steel sheet or strip material. The permeability values for alloys 5 and 6 are plotted in Fig. 2 after end tempering without boron addition to the coating, and in Fig. 3 with boron addition to the coating. The losses in milliwats per 0.454 kg are plotted at the corresponding points on each of the curves representing heats 5 and 6, respectively.

The perfection of the tin-containing melt is evident from a comparison of the magnetic properties, and from 0.013 0.036 <0.002

0.013 0.035 0.02 of the permeability names, in Figs. 2 and 3. Even without boron in the coating, the permeability is greater than 1900 or close to 1900 when hot rolled between 1200 ° C and 1250 ^° C and with boron content in the coating they are permeability higher than 1900 when rolled from near the lowest temperature.

Example 3

In a third experiment similar to Examples 1 and 2, seven melts were prepared, each containing 3.1 percent silicon, 0.1 percent copper and 0.03 percent chromium in the composition compiled in Table III.

TABLE III

Tavba % Qty % S % C ppm B ppm N % Sn 7 0,028 0.013 0,036 7 43 <0.002 8 0,026 0.013 0,035 8 39 0.02 9 0,025 0.014 0,034 6 38 0,047 10 0,025 0.009 0,035 4 38 <0.002 11 0,025 0.009 0,035 4 38 0,023 12 0,027 0.010 0,035 5 35 0,048 13 0.024 0.008 0,036 8 36 0,097 Treatment ending tempering was eekivalent 12 millionths based on same as in Example 1 except that was I put material sheet metal or stripe quartz ·

Five different hot rolling temperatures were used as described in Example 2. In addition, boron was introduced into some magnesium coatings as described in Example 2 and indicated in Tables IV and V, the boron content of the coating in each case being of steel. The magnetic properties of the silicon steel material induced and tested during this description are compiled in Table IV (melts containing 0.013 percent sulfur) and Table V (melts containing 0.009 percent sulfur).

Magnetic properties after final tempering with 0.013% sulfur

Rolling temperature Melt 7 Melt 8 Hot Melt MgO MgO + B MgO MgO + B MgO MgO + B

rQ

3.

N N CD with in CM CM CM CO θ 'CO' 'CD CO CO

CM CO CD CD 00 CM rd rd θ 'CO CD CD rd rd rd rd rd

CD 00 r-1 CM Mi CM 00 00 O CQ

Cd θ 00 θ ts o o o o o co

Ml 03

C3 rd

CD CD rd rd

O O

CD

СЧ θ 'CD U0 CD

O CD C O [> CD t> S

Í CD CM CM 's s CD CD CD 00 CM 00 Θ - CO CD b b b 00 00 00 00 00. to Mi Mi CD CD rd rd rd rd rd

rH г — 1 O WHAT CM O CD CD O r4 t ~ H WHAT OO CD oo rH rH rH i — 1 г — 1 O CM oo 0O 00 00 WHAT 03 / CD b- CD CD

Magnetic properties after final tempering with 0.009% sulfur

0) WHAT CD 03 / O LO Me OO □ 0 03 / 00 v4 00 b · » тЧ rH rH rH y — 1 Ml CM 00 O rH Me CD CD CD CD 00 00 OO OO rH г-1 rH г-1 rH CM CM CM CD LO WHAT Me 00 00 rH CD CD

rH oo Ю oo b- 00 CM ю 00 00 Me CD WHAT oo Ьч тЧ rH rH r-l r-l O O oo LO 00 O bx Ml O CM what rH b * CD r-l r-l

rH WHAT LO 00 O 03 / rH Me LO Me M < Ю CD t> 4 тЧ rH rH rH rH O 00 CD CD CD LO LO 00 O 00 CM CM O CD тЧ rH r-l rH

CM CD

CM bO * к Ен

O CD CD O CD O LO O LO O rH rH CM CM OO rH rH rH rH rH

Example 4

In a fourth experiment similar to Example 1, 2 and 3, ten melts were prepared, each containing 3.1 percent silicon, 0.01 percent copper, 0.03 percent chromium, 0.04 percent carbon, 0.035 percent percent. of manganese, 5 to 10 parts per million of boron and 35 to 65 ppm of nitrogen. 0.05% tin was added to the five melts, while no tin was added to the other five melts. The composition of these melts according to the analysis and the welding behavior of the material produced from them is shown in Table VI.

TABLE VI

Tavba % Qty % S % Sn Parallel cracks Transverse cracks / meter 14 0,034 0.010 <0.002 No 0 15 Dec 0,035 0.013 <0.002 No 16 16 0,037 0.016 <0.002 No 64 17 0,038 0.019 0,022 <0.002 <0.002 Yes 173 18 0,034 Yes 192 19 Dec 0,034 0.010 0,045 No 4 20 May 0,035 0.013 0.040 No 37 21 0,032 0.015 0,046 No 65 22 ¹ · 0,036 0.017 0,045 No 75 23 0,035 0.019 0,049 - -

Table VI shows that as the sulfur content increases, the frequency of cracks in the weld increases, and with a content of 0.018 percent or more sulfur also cracks in the weld parallel to its length. Experiments giving these results and concluding that the occurrence of cracks or cracks is primarily dependent on the sulfur content were performed by simulated welding, in which a tungsten electrode with a diameter of 1.5875 mm at a distance of 0.79375 mm above the cold surface was conducted. rolled strip sample, 1.524 mm thick and clamped in the fixture. At a current of 50 amperes and an electrode flow rate of 20.32 cm per minute, a molten zone of 2.54 mm to 3.81 mm was obtained. After the electrode transition, the test samples fell into three categories:

1. specimens with a significant crack along the weld length ('parallel crack' in Table I) and with other small cracks in the weld;

2. specimens without parallel crack, but with different cracks in and at the weld, oriented at an angle to the weld; ("Transverse cracks" in Table VI);

3. crack-free samples, as confirmed by the use of the dye commonly used for crack detection.

This experiment exaggerates the tendency of the cracking material, since it is assumed that the material that constitutes only transverse cracks will be weldable by suitable techniques.

FIGS. 4 and 5 show the magnetic properties of the ten heats after final release. No boron was added to the coating prior to tempering. Losses at 17.10 ^{1 1} T and 60 Hertz are given for the relevant points. The excellent magnetic properties of the sulfur-containing melts are evident. From the welding behavior shown in Table VI and from the magnetic properties of Figures 4 and 5, it is apparent that the addition of tin can achieve high permeability and low losses in melts with a sufficiently low · sulfur content to not show "parallel cracks" in the evaluation welding.

Example 5

Five laboratory melts were melted in an air induction furnace under an argon hood using electrolytic iron and 98 percent ferro-silicon, containing a total of 3.1 percent silicon (Si), 0.022-0.026 percent manganese (Mn), 0.003 to 0.005 percent sulfur (S) , less than one part or 7 to 10 parts per million of boron (B), 41 to 58 parts per million of nitrogen (N), 0.01 percent copper (Cu), 0.03 percent chromium (Cr) and 0.038 to 0.041 percent carbon (C) . Antimony (Sb) was added to the separate melts in varying amounts to obtain an antimony content range of 0.001 to 0.041 percent. In Table VI! the approximate amounts of said components of these melt are indicated by analysis in ascending order of antimony content. The percentages and parts are based on the weight of each heat starting with Heat 1.

TABLE VII

Melting% /% Sb% Mn% S

Mn / S ppm B ppm N B / N

1 0.001 0,025 0.005 5.0 7.1 41 6 2 0.014 0.024 0.006 4.0 8.4 58 7 3 0.030 0,022 0.005 4.4 7.0 45 6.5 4 0,031 0,031 0.006 5.0 nothing 55 nothing 5 0,041 0,026 0,006 ' 4.3 8.4 58 7

Slices of 4.445 cm thickness were cut from ingots cast from these melt and hot rolled at 1200 ° C in six punches to form warm strips of approximately 2.286 mm thickness. After pickling, the hot strip samples were heat treated at 950 ° C, with a time between 930 and 950 ° C being about 3 minutes. The warm strips were then cold rolled to a final desired thickness of approximately 0.2794 mm. Then, the Epstein-size cold-rolled strips were decarburized to less than 0.006 percent carbon by heating for two minutes at 800 ° C in 20 ° C dew point hydrogen. At 0.04 percent Sb, the carbon level after the decarburization heat treatment is approximately 0.015 percent. This leads to higher losses but does not affect permeability. Lower carbon levels and losses can be achieved by using a higher dew point tempering atmosphere. The decarburized strips were brushed with magnesium milk to a weight gain of approximately 40 mg per strip. A 0.5 or 1.0 percent boric acid solution in water was brushed on one of the magnesium coated strips using sufficient amounts of solution so that if all of the boron in the resulting coating was absorbed by the silicon steel, the boron content of the alloy would increase by 12 or 24 ppm as indicated in Table VIII. The resulting coated strips comprising both boric acid-brushed strips and strips that were not so treated were subjected to a final tempering step of heating at 40 ° C per hour from 800 ° C to 1175 ° C in dry hydrogen, and this temperature was maintained for three hours.

The results of tests carried out on Epstein beams assembled from strips prepared from melts 1 to 5 to determine the magnetic properties (energy loss and permeability) after their final tempering are shown in Table VIII.

TABLE VIII

Magnetic properties of melts 1 to 5 after final tempering

Approximate amount of boron deposited in the coating ppm 12 ppm 24 ppm

Tavba (a) at (c) μ (b) (a) at (c) μ (b) (a) at (c) μ (b) 1 1341 1503 1332 1506 1298 1499 2 1186 1594 748 1856 746 1844 3 1197 1621 746 1865 905 1760 4 1326 1490 1306 1496 1304 1489 5 1088 1641 692 1901 686 1900

Ja) Power loss in milliwats to 0.454 k g at 17.10 1 1 T magnetic induction from AC at 60 Hert remains.

(b) Magnetic permeability μ at (10 000/4 π). Am '1.

(c) Magnetic induction 17.10 ^_1 T.

The data show that for a given coating, losses generally decrease and the permeability increases as the antimony content increases, assuming the melt contains boron (the melt for melting 4 contained practically no borj. The data further show that generally for a given melt containing the given content Low loss and high permeability of the melt strips 5 (0.041 percent Sb in melt) tempered with boric acid coatings are comparable to the properties of the hitherto sought silicon steels with high permeability. It is apparent from the data that the presence of only about 0.01 percent of antimony, especially when adding boron to the coating, leads to a significant improvement in magnetic properties.

Melts 1 to 5 inclusive were evaluated for weldability by passing a hot melt strip of approximately 12.7 cm in length along a cold-rolled strip of 1.655 mm thickness. None of these melts showed any cracks, suggesting a substantial absence of brittleness in the weld. Laboratory melts with the same manganese content, without antimony, and containing approximately 0.02 percent sulfur to inhibit grain growth, show very significant crack formation in the same experiment. In a more detailed procedure were the tests giving these results. and concluding that the occurrence of cracks is primarily dependent on the sulfur content of the simulated welding, depending on the fact that the tungsten electrode of 1.587 mm diameter was guided at a distance of 0.79375 mm above the surface of the cold rolled strip clamped in the fixture. With a current of 80 amperes and an electrode advance of 203.20 mm per minute, a molten zone of 2.54 to 3.41 mm was obtained.

Example 6

Two laboratory melts were prepared per

TABLE IX using the procedure of Example 1 with the following differences. The melt composition for these melts (6 and 7) was essentially the same as for melts 2 and 3, respectively, except that a higher nitrogen content was used. In Table IX, approximate amounts of the indicated components of these melts are given by analysis, unless otherwise indicated.

Melting% Sb% Mn% S ppm В ppm N

B / N

6 0.014 0,025 0.005 (10) * 100 ALIGN! (0,10) 7 0,038 0.024 0.003 (1O) ‘ 86 (0Д1)

* Not analyzed for boron (M). 10 ppm of boron was added in the melt preparation.

Progress from the melt stage to the final tempering state was the same as described in Example 5.

The approximate boron content of the coatings was varied in increments of 12 ppm from zero ppm to 60 ppm based on the sheet material or the strip of silicon steel. Permeability and energy loss result from testing of Epstein beams formed from strips of these sheets as shown in Table X.

TABLE X

Magnetic properties of melts 6 and 7 after end tempering ppm В applied in coating Melt 6 Melt 7

(a) at (c) μ (b) (a) at (c) μ (b) 0 865 1787 1192 1598 12 733 1859 737 1876 24 724 1873 673 1897 36 700 1875 674 1897 48 672 1889 713 1887 60 681 1884 753 1839

(a): mW / 0.454 kg (b): (10,000/4 π). Am-1 (c): 17.10-1. t

The data again show that the magnetic properties are improved by boron coating, i.e., the energy loss is reduced and the magnetic permeability is increased. In addition, this improvement increases significantly as the amount of boron deposited in the coating increases, until a maximum improvement is achieved. A comparison of melts 6 and 7 shows that such a maximum occurs at a higher boron content in the coating for melts prepared from melts having a higher nitrogen content. (The maximum occurs between 36 and 60 ppm of boron deposited in the melt coating 6 prepared from the melt containing 100 ppm of nitrogen, while between 24 and 48 ppm of boron for melting 7 with 86 ppm of nitrogen in the melt). A comparison of the properties of melting 6 (0.014 percent antimony coated with 12 ppm boron) with melting 2 (also 0.014 percent antimony coated with 12 ppm boron) shows that at lower levels of antimony the higher nitrogen content (100 ppm versus 58 ppm) increases the magnetic properties. This beneficial effect of increasing the nitrogen content is not achieved at the higher levels of antimony used in heats 5 and 7.

Example 7

Seven laboratory melts (numbered 8-14) were prepared using the procedure of Example 5 with the differences below. The melt compositions for these melts were essentially the same as for melts 1 to 5, except for the following approximate amounts of labeled components: 0.04 percent manganese, 0.030 to 0.040 percent carbon, 10 ppm boron (added but not analyzed), 27 to 52 ppm nitrogen, 0.006 to 0.021 percent sulfur in melts containing no antimony (heats 8-12) and 0.006 to 0.011 percent sulfur in melts containing antimony (0.045 percent Sb at melt 13 and 0.046 percent Sb at melt 14). In Table XI, approximate amounts of the indicated components of each melt are compiled according to analysis.

1ti

TABLE XI

Melting composition and magnetic properties

B coating is not applied in the coating

Tavba % Sb. s% Mn / S ppm N (and during (C) μ (b) is applied B (and during (C) μ (b) 8 without 0,006! 5.7 27 Mar: 1344 1495 1318 1503 9 without 0.009 3.8 35 1372 1480 1226 1483 10 without 0.013 2 ', 6 44 1381 1495 1369 1499 11 without 0.017 2,0 45 1380 1491 1299 1544 12 without 0,021 1.6 50 954 1774 758 1870 ' 13 0,045 0.006 5.7 38 743 1848 767 1867 14 0,046 0.011 3.2 37 718 1878 719 1916 12 ppm B applied in the coating, relative. n

and substrate weight.

(a): .mW / 0.454 kg (b): (10,000/4 π) .Ami (c): 17.1П-1. T

The data show that in the absence of antimony, permeability is low until the sulfur level increases to 0.021 percent (melt 12). However, at 0.046 percent antimony and only 0.011 percent sulfur (melt 14), high permeability (1878) is obtained without boron deposition, and higher permeability (1916) is achieved with boron deposition.

Melts of 8 to 14 inclusive were evaluated for weldability using the experiment given in Example 5 except that the cold-rolled strips had a thickness of 1.65 mm.

This attempt exaggerates any slope of the cracking material. It is expected, . It will be appreciated that a material that only produces transverse cracks and less than 10 such cracks per meter will be suitably weldable using known welding processes using, for example, fillers and narrower. molten zone. The results of the weldability tests for melts 8 to 14 are compiled in Table XII, where the sulfur and antimony contents of the melts are also given.

Melting composition and weldability TABLE XII % Sb Parallel cracks * Transverse cracks per meter Tavba % S 8 0.006 0 No 0 9 0.009 0 No 0 10 ' 0.013 0 No 4 11 0.017 0 No 63 12 0,021 0 anc * 200 13 0.006 0,045 No 8 14 0.011 0,046 ' No 4

*. It runs substantially along the entire length of the weld.

The data in Table XII show that the number of transverse; · Cracks. increases with an increase in sulfur content above about 0.01 percent sulfur, and in melts containing more than about 0.015 percent sulfur, the formation of transverse cracks is significant, while the formation of parallel cracks (representing extraordinary brittleness of the weld) occurs at about 0.021 percent. open.

Melts appearing less than about 10 transverse cracks per meter. in this experiment are assumed to be appropriate. weldable. . Although the low sulfur melts 8-11 show a suitable degree of absence of brittleness in the weld, they are sacrificed. magnetic properties (see Table XI). By comparison, melts 13 and 14 containing antimony appear to be suitable for welding. (Table XII), as well as excellent magnetic properties (Table XI).

Claims (2)

SUBJECT A method for producing a grain oriented silicon steel foil having a structure (110) [001], characterized in that a silicon steel melt containing 2.2 to 4.5 wt. % silicon, 0.003 to 0.0035 wt. % boron, 0.003 to 0.0075 wt. % of nitrogen, wherein the boron to nitrogen ratio is 1 to 15, 0.02 to 0.05 wt., the percentage of manganese, 0.005 to 0.025 wt. % sulfur and tin or antimony in amounts of from 0.01 to 0.1 wt. %, wherein the content of nitrogen, boron, manganese, sulfur and tin or antimony is less than 0.2% of the melt using the maximum declared amounts, the remainder iron, odvynAlezu pour, the cast ingot is hot rolled into an elongated body, then cold-rolling into a sheet or film of a predetermined thickness and the resulting cold-rolled film is decarburized by final heat treatment and recrystallized to a secondary structure (110) [001], 2. A process according to claim 1, characterized in that a cold electrically insulating adhesive coating containing 0.0015% by weight is applied to the rolled silicon steel strip prior to heat treatment. % boron based on the weight of the silicon steel strip.