EP2625298A1

EP2625298A1 - Method for producing an insulation coating on a grain-oriented electrical steel flat product and electrical steel flat product coated with such an insulation coating

Info

Publication number: EP2625298A1
Application number: EP11764510.1A
Authority: EP
Inventors: Carsten Schepers; Chaoyong Wang; Ludger Lahn; Heiner Schrapers; Stefan Pahlke
Original assignee: ThyssenKrupp Electrical Steel GmbH
Current assignee: ThyssenKrupp Electrical Steel GmbH
Priority date: 2010-10-07
Filing date: 2011-09-22
Publication date: 2013-08-14
Also published as: KR20130117789A; CN103221556B; WO2012045593A1; BR112013008376A2; US20130251984A1; JP5980216B2; RU2013120538A; DE102010038038A1; RU2580778C2; KR101896046B1; CN103221556A; JP2013542323A

Abstract

The invention relates to a method for producing a grain-oriented electrical steel flat product with minimized magnetic loss values wherein the method comprises the following work steps: a) providing an electrical steel flat product, b) applying a layer of a phosphatic insulation solution for at least one surface of the electrical steel flat product and baking the applied layer. In order that the tensile stresses acting on the surface of an electrical steel flat product are increased further by means of such a method, the invention proposes that, after carrying out work step b) for a first time, said work step b) is repeated at least once, such that an insulation layer is obtained from the layers of the phosphatic insulation solution that are successively applied to one another and baked.

Description

Process for producing an insulation coating on a grain-oriented electro-steel flat product and electrical steel flat product coated with such an insulation coating

The invention relates to a method for producing a grain-oriented electrical steel flat product with minimized magnetic loss values.

Likewise, the invention relates to a grain-oriented electrical steel flat product, which is provided with an insulation coating.

The grain-oriented electrical steel flat products in question here are steel strips or sheets from which parts are manufactured for electrotechnical applications. Grain-oriented electrical steel flat products are particularly suitable for uses in which a particularly low

Loss of magnetization is in the foreground and high demands are placed on the permeability or polarization. Such requirements exist in particular for parts for power transformers, distribution transformers and higher quality small transformers. As explained in detail, for example, in EP 1 025 268 B1, is generally in the course of the production of

Steel flat products, first a steel containing (in% by weight) typically 2.5 to 4.0% Si, 0.010 to 0.100% C, up to 0.150% Mn, up to 0.065% Al and up to 0.0150% N and optionally 0.010 to 0.3% Cu, to 0.060% S, to 0.100% P, to 0.2% each of As, Sn, Sb, Te and Bi, balance iron and unavoidable impurities, to a starting material, such as a slab, thin slab or a cast strip, shed. The starting material is then subjected, if necessary, to an annealing treatment to be subsequently hot rolled into a hot strip.

After reeling and an optional addition

performed annealing as well as one as optional

completed Entzunderungs- or pickling treatment is then rolled out of the hot strip in one or more steps, a cold strip, between the cold rolling steps, if necessary, an intermediate annealing can be performed. In the subsequently performed

Decarburization annealing is usually significantly reduced to avoid magnetic aging of the carbon content of the cold strip.

After decarburization annealing, an annealing separator, which is typically gO, is applied to the belt surfaces. The annealing separator prevents the turns of a coil wound from the cold strip during the subsequent high-temperature annealing

weld together. During the

High temperature annealing, typically in one

Hood furnace is performed under protective gas, arises in the Cold strip through selective grain growth the texture. Furthermore, a forsterite layer, the so-called "glass film", forms on the strip surfaces. In addition, by running during the high-temperature annealing

Diffusion processes cleaned the steel material.

After the high-temperature annealing, the thus obtained electric steel flat product with a

Insulating layer coated, thermally directed and annealed in a final "final annealing" stress relieved. This final annealing can be done before or after

Assembling of the steel flat product produced in the manner described above to those for the

Further processing required blanks take place, which can be reduced by a final annealing after dividing the blanks incurred in the course of the Abteilvorgangs additional stresses. As a rule, electrical steel flat products produced in this way have a thickness of 0.15 mm to 0.5 mm.

The metallurgical properties of the material, the degrees of cold rolling set in the production of electro-steel flat products and the parameters of the heat treatment steps are coordinated so that targeted recrystallization processes take place. These recrystallization processes lead to the typical for the material "Goss texture" in which the direction of the easiest magnetization in the rolling direction of the finished strips. Grain-oriented electrical steel flat products accordingly have a strongly anisotropic magnetic behavior. In addition to energy losses, noise generation also plays a role in transformers. This is based on a known as Magnetostrikt ion physical effect and is among other things influenced by the properties of the electrical steel core material used.

It is known that the insulation layer applied to an electro-steel flat product has a positive effect on the

Minimizing the re-magnetization losses. Thus, the insulation layer tensile stresses on the

Transfer base material, which not only improve the magnetic loss of the electrical steel flat product, but also reduce the magnetostriction, which in turn has a positive effect on the noise behavior of the finished transformer.

An insulating layer exhibiting these effects and a process for their preparation are described, for example, in DE 22 47 269 C3. The main components of the according to this prior art for the production of

Insulating layer used isolation solution

Aluminum phosphate and silica, the latter can also be added in colloidal form. Another ingredient of insulation coatings is common

Chromsäureanhydrid (chromium trioxide) or chromic acid, wherein the content of this questionable with regard to its impact on the environment component can be minimized with a suitable choice of the other ingredients of the insulating solution (DE 10 2008 008 781 AI, EP 2 022 874 AI).

Common to the above-mentioned known

Insulation layers that they first on the optionally already coated with a glass film

Surface of the coated electrical steel flat product are applied, then the thickness of the insulating layer is set, for example by means of Äzwquetschrollen and finally in an oven, the insulating layer is baked. The stoving temperature is typically about 850 ° C.

The insulation layer produced in this way exerts a considerable tensile stress on the base material after firing. In EP 2 022 874 A1 values of up to

0.8 kg / mm ² , which corresponds to a tensile stress of about 8 MPa. According to the DE 22 47 269 C3 on

This effect is reflected in the

different coefficients of thermal expansion of insulation layer and base material justified. According to DE 22 47 269 C3, layer densities of up to 4 g / m ^{2 are} achieved.

The demands made on minimizing noise in the operation of transformers are constantly increasing. On the one hand, this is due to continuously tightened legal requirements and standards. On the other hand, consumers today generally no longer accept electrical appliances that cause an audible "transformer drone". Today, the acceptance of large transformers in the vicinity of residential buildings depends crucially on the noise emissions that result in the operation of such transformers.

Practical experience shows that with conventional state-of-the-art Flat steel products increasing

Requirements can not be met easily. This is because the much higher transmitted tensile stress needed to meet these requirements can not be achieved by simply modifying the coating process. It has been shown that one

Increasing the thickness of the insulation layer does not lead to the goal, as it produces more gases during firing, the unfavorable the morphology of the finished layer

influence. This is how one gets too thick

Insulation layer Pores, which in extreme cases cause the layer to flake off because of cohesiveness. The resulting in insulation layers with a greater thickness

Problems can also be recognized by the fact that, despite an increased layer thickness determined by observation of a metallographic cut in the scanning electron microscope (SEM) and given in "μπι", the layer density reached, which is given in g / m, and the weight difference after selective removal of the insulating layer is determined, only increases disproportionately.

Against this background, the object of the invention was to demonstrate a process which can be implemented in practice with simple means, with which the tensile stresses acting on the surface of an electro-steel flat product can be further increased. In addition, an electric steel flat product should be specified, the optimum

magnetic properties and in practical use also has an optimized noise behavior.

In terms of the procedure is this task

The invention has been solved in that at the Production of an electrical steel flat product, the operations specified in claim 1 are performed.

With regard to the electro-flat steel product, the solution according to the invention is as stated above

Task in that such a flat product in

Has claim 13 specified features.

Advantageous embodiments of the invention are specified in the dependent claims and are explained below as the basic idea of the invention in detail.

In the method according to the invention for producing a grain-oriented electrical steel flat product with minimized magnetic loss values, at least the following steps a) and b) are performed in accordance with the prior art explained at the outset:

Step a)

An electro-steel flat product is provided.

Special requirements for the way the

Production of the provided electric steel flat product does not exist. So that can be for the inventive

Method provided by electro-flat steel product using the given to the expert, for example, in the publications already mentioned above instructions and made on the basis of steel alloys. Of course, this also includes such

Manufacturing processes, which are not yet known, but where, as in the prior art, the Applying and baking an insulation layer is provided.

Step b)

Applying a layer of a phosphatic insulation solution to at least one surface of the electrode

Flat steel product and baking the applied layer.

The way of the job, the setting of the

Layer thickness, the composition of the insulating solution and the manner of burning the from the

Isolation solution formed insulating layer can also be made on the model of the prior art selected.

According to the invention, after a first execution of the working step b), this working step b) is repeated at least once, so that as a result an insulation layer is obtained from the layers of the phosphatic insulating solution successively applied to one another and baked.

According to the invention, therefore, an increased layer thickness of the insulation layer is produced by carrying out at least two separate coating steps, with the first insulation layer layer initially finished

is burned, then at least one more

Insulation layer layer applied and also

is burned. If necessary, more

Repeatedly the coating and baking process can be carried out to even greater by applying and baking further layers of insulation solution Layer thickness to produce. However, practical experiments have shown that even in a simple repetition summarized here under step b)

Process sequence "application of the coating" and "baking of each applied layer of insulation solution" a significant increase in the transmitted to the steel substrate of an electric steel flat product tensile stresses is achieved.

According to the invention, the insulating layer is thus characterized by at least two layers of a phosphatic

Insulating agent formed, each by itself

applied and baked. Together, the insulation layers then form an insulating layer, which is characterized by a high specific layer density and large thickness.

By the insulating layer is produced according to the invention by in separate steps in each case applied and baked layers of insulating solution, the unfavorable development of the specific

Layer thickness compared to the layer thickness avoided, which occurs when a thick insulating layer is applied in a single operation. With the invention, it is possible to achieve such large layer thicknesses at very high specific temperatures

Create layer densities. This is reflected in the

reached tensile stresses, magnetic loss values or apparent powers and magnetostriction values as well as the noise levels determined therefrom (LvA value = A-weighted magnetostriction velocity level). As a result, it is possible to obtain from electrogenerated In particular, flat steel products produce, in particular, sheet metal for transformers, in which the noise emissions in comparison with transformers made from conventional

Electro sheets are produced, are significantly reduced.

The phosphatic isolation solution used to produce the insulation layer in step b) may already be proven in practice for this purpose

Isolation solutions comprise a colloid component, which may be in particular a colloidal silica.

In principle, an isolation solution used according to the invention for the production of the insulation layer can contain a wide variety of phosphates. Especially good

However, results are achieved with a phosphate isolation solution containing aluminum and / or

Magnesium phosphate contains. The basis for the phosphate solution is preferably water. It can, however

Of course, other solvents are used, provided that they have a similar reactivity and polarity as water.

According to a preferred embodiment of the invention, the isolation solution further contains at least one additive selected from a group, the pickling inhibitors and

Wetting agent includes. Through the use of pickling inhibitors and / or wetting agents, the properties of the grain-oriented electro-steel flat product produced by the method according to the invention can be further improved.

In order to produce the inventive

Insulation layer used isolation solution one Contains colloid stabilizer as an additive can be ensured in a conventional manner that the transition from sol to gel takes place only during the drying of the phosphate layer. In addition, the use of colloid stabilizers enables a homogeneous application of the

Phosphate solution whereby homogeneous Fertigschichtqualitäten can be achieved.

Detailed explanations of the possible composition of an isolation solution, which for the inventive

Generation of an insulating layer on an electric steel flat product in question, can be found

For example, in DE 10 2008 008 781 AI.

Depending on the production conditions and the

it may be desirable properties

be expedient, in the at least one repetition of the operation b) one compared to the first

Execution of the step b) used

Isolation solution modified isolation solution too

use. However, practical investigations have shown that a particularly good adhesion and a particularly high specific layer density r of the invention according to the invention applied in at least two layers insulation coating results, if for the first as for each other

Run through the step b) identical composite insulation solutions can be used.

Important for the invention is that in each

previous step b) applied and

burned layer of the insulating layer is completely baked before repeating the Step b) the further layer of insulation solution is applied. This assumes that at the

Burning treatment reaches a temperature level that goes beyond the level of simple drying. Accordingly, the invention provides, in a practical embodiment, that in the course of work step b)

the baking temperature is at least 300 ° C.

In terms of process economics, it proves to be particularly advantageous if the stoving temperature is at least 700 ° C. at least in the course of the last repetition of the working step b). At this temperature level, the

Burn-in treatment can be combined with a stress-relieving, usually by the procedure

almost eliminating unavoidable tensions. The annealing can be carried out in a continuous furnace in air as a short-time annealing or in a muffle furnace (long-term annealing) under nitrogen, which in combination with the

Baking treatment the Kurzzeitglühung with regard to the formation of a high specific layer density and optimal adhesion of the invention produced

Insulation coating has proven to be particularly advantageous. The burn-in result is particularly safe

Combined with the reduction of possibly existing voltages when the stoving temperature is at least 800 ° C, in particular about 850 ° C. To avoid unwanted changes of the structure of the steel substrate of the

To avoid in accordance with the invention processed electrical steel flat product, should at the same time in the course of the

Work step b) carried out the burn Stirring each be at most 900 ° C, in particular below 900 ° C held.

In principle, it is of course conceivable to use the same unit for the repetitions of the working step b). However, the method according to the invention can be carried out in a particularly economical manner when the repeated execution of the working step b) of a treatment line is arranged in succession in a line corresponding to the number of repetitions corresponding number of devices for applying and baking the insulation solution be traversed to be coated electric steel flat product in a continuous pass. If, for example, the insulation coating is to be formed in accordance with the invention from two successively applied and baked layers of insulation solution, then in such a line, in succession, a first device for applying and baking the first layer of the insulating layer and a second device for applying it will follow one another and baking the second layer through.

In accordance with the invention produced and procured electric steel flat products, the ratio of layer thickness to specific layer density and the ratio of layer thickness to tensile stress in each case in an optimized range. As practical investigations have shown, these areas are more favorable for practical application than the areas in which the properties in question lie when a correspondingly thick insulation layer in applied and baked in a single operation.

An inventively designed grain-oriented electrical steel flat product, which on at least one of its

Surfaces a branded phosphatic

Insulation layer is accordingly characterized in that in the case that the thickness D of the

phosphatic insulation layer ^ 3 μτα is that

specific layer density r of the phosphatic

Insulation layer ^ 5 g / m ² , while applies at a thickness D> 3 μτ for the specific layer density r of the phosphate insulating layer: r [g / m ² ]> 3/5 g / pm / m ² * D [μπι].

This results in the case that the specific

Layer density r of the phosphatic insulation layer ^ 5.0 g / m ² , a tensile stress Z transmitted through the insulation layer satisfies the following condition:

Z [MPa]> 7/6 MPa * m ² / g * r [g / m ² ].

In the above-mentioned manner procured electric steel flat products can be produced economically, reliably and reliably by applying the method according to the invention.

The invention will be explained in more detail by means of embodiments and comparative examples. Show it: Fig. 1 is a diagram in which for various inventively double and conventionally simply coated samples specified in g / m ²

specific layer density r over in μιτι

indicated thickness D of the respective insulating layer is applied;

Fig. 2 is a diagram in which for different

According to the invention doubly and conventionally simply coated samples of the respective

Insulation layer applied to the steel substrate of the electro-steel flat product, in tensile stresses specified in MPa over that specified in g / m ²

specific layer density r of the respective

Insulation layer is applied.

In the diagram shown in FIG. 1, the specific layer density values r determined for the samples coated twice according to the invention are over the respective thickness D of the insulation layer through filled triangles

while the specific layer density values r determined for the conventional samples are symbolized by filled circles over the assigned thickness D of the insulation layer.

It turns out that in accordance with the invention

coated samples at layer thicknesses of at least 3 μιτι regularly have specific layer densities r, the condition r [g / m ² ]> 3/5 q /) i / m ^z * D [m] meet. With less than 3 μπι thick insulation layers resulted in a specific layer density r, which is greater than 4 g / m ² , wherein in view of the invention sought after Properties the limit of the specific layer density r for the requirements of the invention yet

satisfying, less than 3 pm thick insulation layers at 5 g / m ^{2 has been} set. In the results shown in Fig. 1, this requirement is met by samples in which the thickness D of their insulating layer is at least 2 μηα.

As in the diagram shown in FIG. 1, in the diagram shown in FIG. 2, the tensile forces Z determined for the samples coated twice in accordance with the invention are filled through the respective specific layer density r

Triangles indicated while the determined for the conventional samples tensile stresses Z on the associated specific layer density r of the insulation layer are symbolized by filled circles.

It can be seen that in the samples coated twice according to the invention, the insulating layer always exerts higher tensile stresses Z on the steel substrate of the respective electrical steel flat product than in the conventional one train with an insulating layer of the same

specific layer density r coated samples.

This becomes particularly clear in the case of samples in which the specific layer density r is at least 5.1 g / m ² . Accordingly, the requirements arising in practice are in particular those according to the invention

Electric steel flat products, for which applies

Z [MPa]> 7/6 MPa * m ² / g * r [g / m ² ].

To demonstrate the effects achieved by the invention, eleven experiments VI - V10 were carried out, of which the Experiments VI, V2, V4, V7 and V9 were prior art, while experiments V3, V5, V6, V8 and V10 were according to the invention.

In each experiment, a sheet metal blank of the format 350 mm x 60 mm and a nominal thickness of 0.30 mm from a grain-oriented electrical steel, from the

conventional production of the applicant, im

Condition used after high temperature annealing. The

Steel strip contained in the decarburized state in addition to iron and unavoidable impurities (in wt .-%) C: <0.0025%, Si: 3.15%, Mn: 0.08%, S: 0.02%, Cu: 0 , 07%, Sn: 0.08% and AI: 0.03%. , As a hot strip, the steel strip in the uncarboxylated origin state contained 0.06 wt .-% C.

The samples were cleaned and in one

Coating system coated on both sides with an insulating solution. To set the respectively desired

Layer thickness included the coating system a double pair of squeezing rollers. By adjusting the distance of the squeezing rollers from their associated surface of the samples, the respective desired layer thickness could be adjusted in a targeted manner.

The aqueous used in the experiments

Isolation solutions contained the following constituents per liter, the gram data being absolute and "()" indicating the respective concentrations:

Try V1-V6

150g onoaluminium phosphate (50%)

183g colloidal silica (30%)

12g chromium trioxide Try V7, V8

150g monoaluminum phosphate (50%)

183g colloidal silica (30%)

2g Pickling inhibitor with active ingredient diethylthiourea 10g Colloid stabilizer with active ingredient triethyl phosphate

Try V9, V10

150g monoaluminum phosphate (50%)

183g colloidal silica (30%)

2g Pickling inhibitor with active ingredient Diethylthiourea 10g Colloid stabilizer with active substance Triethyl phosphate 36g Chromium (III) nitrate nonahydrate

In Table 1, for the experiments Vi - V10, the thickness D produced in each case of the insulating layer is specific

Layer density r of the insulating layer, the

Correction loss Pi, 7 _/ so at a frequency of 50 hertz and a polarization of 1.7 Tesla, the

Apparent power Si _7/5 o at a frequency of 50 Hertz and a polarization of 1.7 Tesla, the Lv _A value, the La _Ä value and the applied by the respective insulating layer on the steel substrate of each sample tensile stress indicated.

The respective thickness D of the insulating layer is through

Examination of a micrograph of the respective sample was determined in the scanning electron microscope.

The specific layer density r of the insulating layer is hotter by removing the phosphate layer at 60 ° C

Sodium hydroxide solution (25%) was determined. The tension exerted by the insulating layer is determined by determining the difference in curvature of the respective sample before and after unilateral removal of the

Insulating layer has been determined.

Experiment VI (not according to the invention)

The sample is on both sides with the isolation solution

been coated. By appropriate adjustment of the squeezing rollers the specified in Table 1 low layer thickness has been set.

Immediately after application of the insulating layer, the layer was at 840 ° C for 1 min under a

Nitrogen atmosphere burned.

The tensile stress of the insulation was determined in the following manner:

One side of the sample was taped with resistant film. The sample was placed in 60 ° C hot caustic (60%) for 10 minutes. The previously applied and baked phosphatic isolation layer on the unprotected side was removed in this manner without attacking the underlying glass film / forsterite.

The curvatures of the sample were before and after this

Determined treatment and calculated from the difference of the transmitted through the insulation layer tension.

From the weight difference of the sample before and after the removal of the insulating layer could also

specific layer density r can be determined. Experiment V2 (not according to the invention)

The squeeze rollers were opened wider than in Experiment VI, so that when applying the insulation solution, a slightly larger layer thickness, as is customary in industrial production.

Immediately after application, the film was baked at 840 ° C for 1 minute in a nitrogen atmosphere.

The specific layer density determined for this sample corresponded approximately to the usual production practice.

Experiment V3 (according to the invention)

The squeezing rollers of the coating device were set with less pressure than in the experiment Vi, to a greater thickness of each layer applied

Achieve isolation solution.

Immediately after application, the applied layer was again baked at 840 ° C. for 1 minute under a nitrogen atmosphere.

Subsequently, the coating process was repeated. For this purpose, the sample was run a second time in the same manner as the first time through the coating plant to apply a second layer of insulation solution to the already baked layer. Also immediately after this second application, the film was baked at 840 ° C for 1 minute under a nitrogen atmosphere. The magnetic characteristics obtained for the sample processed in experiment V3 as well as the magnetostriction with LvA and LaA values are much higher despite a smaller thickness than in the sample processed according to experiment V2.

The same applies to the insulation layer

applied tensile stress Z. This was thus significantly higher than the values that have been determined for Experiment V2 despite a significantly lower thickness D of the insulation layer.

Experiment V4 (not according to the invention)

The squeeze rolls of the coater were adjusted to achieve a thicker layer than usual. Immediately after application, the layer was left for 1 minute at 840 ° C in a nitrogen atmosphere

branded.

Despite the much thicker layer, the one produced by the one-time coating was the same

Insulation layer applied to the steel substrate of the sample tensile stress at 7.5 MPa well below the tensile stress, the inventively generated in experiment V3

Insulation layer exercised.

Trial V5 (according to the invention)

The squeeze rolls of the coater were set narrower than in Run V4. Immediately after application, the resulting layer of isolation solution was baked at 840 ° C. for 1 minute in a nitrogen atmosphere. Subsequently, the coating process was repeated.

For this purpose, the sample was run a second time in the same manner as the first time through the coating plant to apply a second layer of insulation solution to the already baked layer. Also immediately after this second application, the film was baked at 840 ° C for 1 minute under a nitrogen atmosphere.

The magnetic characteristics including the

Magnetostriction with the LvA and LaA values are, despite the same thickness, significantly better than with the sample generated in experiment V4.

The tensile stress exerted by the insulating layer on the steel substrate of the sample gave a very good value of 14.0 MPa. It is thus significantly better than the applied tensile stress in the sample processed in experiment V4.

Also the specific layer density r here

In spite of the same layer thickness D, the sample coated twice according to the invention was significantly higher than in the sample produced in experiment V4.

Experiment V6 (according to the invention)

The squeezing rollers were adjusted as in experiment V5.

Immediately after the application became the layer

Baked for 10 seconds at 300 ° C in a nitrogen atmosphere.

Subsequently, the sample was again with the same setting of the squeezing rollers by the

Driven coating system. Immediately thereafter, under a nitrogen atmosphere, a renewed In this case, the baking time was 1 minute and the baking temperature was 840 ° C.

The properties of the sample thus processed are approximately equal to those of the sample processed according to experiment V5

comparable.

The tensile stress transferred from the insulating layer to the steel substrate gave a value of 12.5 MPa. It is therefore also similar to the high in accordance with

Try V5 generated sample.

Thus, the burn-in of the first of the

Isolation solution formed possible even at lower temperatures. However, the burn - in the repetition of the painting and baking a

Insulation layer at a higher temperature, in order to exploit the difference in the coefficient of thermal expansion for the generation of the tensile stress can.

The advantage of such a procedure, in which the first layer of the insulating layer is baked at a low temperature, is that ovens with lower stoving temperature and shorter Einbrennzeit can be easily integrated into existing operational continuous incandescent and thus the overall coating process in principle a line

can be carried out.

Trial V7 (not according to the invention) To determine the properties of a sample prepared in a conventional manner with a Cr-free, but a colloid stabilizer-containing isolation solution

is coated, the squeezing rollers have been adjusted similar to Experiment V2. Immediately after the

Application, the layer was baked for 1 minute at 840 ° C under a nitrogen atmosphere and determined the properties given in Table 1 of the sample thus obtained after a single coating.

Experiment V8 (according to the invention)

The squeezing rollers were set similarly as in experiment V5. Immediately after application, the layer was baked at 840 ° C. for 1 minute under a nitrogen atmosphere.

Subsequently, the coating process was repeated. For this purpose, the sample was run a second time in the same manner as the first time through the coating plant to apply a second layer of insulation solution to the already baked layer. Also immediately after this second application, the film was baked at 840 ° C for 1 minute under a nitrogen atmosphere.

Thereafter, the properties given in Table 1 of the thus obtained after a double coating and baking treatment sample are determined. It also shows a clear superiority of in

according to the invention in two passes with the

Insulation layer coated sample.

Trial V9 (not according to the invention) To determine the properties of a sample containing in a conventional manner with a Cr-containing and a

Colloid stabilizer containing isolation solution

is coated, the squeezing rollers are similar

set as in the experiment V2. Immediately after the

Application, the insulation layer was baked here for 1 minute at 840 ° C under a nitrogen atmosphere. The properties of the sample thus produced are also given in Table 1.

Experiment V10 (according to the invention)

The squeezing rollers were set similar to those in experiment V5. Immediately after the application was the

Layer 1 minute at 840 ° C under a

Nitrogen atmosphere burned.

Subsequently, those given in Table 1

Properties of the sample thus obtained has been determined. It also shows here a clear superiority of the inventive manner in two passes with the insulating layer coated sample. spec. SchichtPl, 7/50 Sl, 7/50 I "V _A 1.7 / 50 La _A i, 7/50 Tensile chip

Density Z

[um] [g / m ² ] [W / kg] [VA / kg] [dB] [dB] [MPa]

1.5 2.1 1.070 1, 327 54.2 46, 1 3.2

3.5 4.5 1.040 1.245 53.0 45, 0 5.9

3, 0 6.7 0, 979 1, 190 51.2 42, 4 10, 1

5, 0 7,1 1, 029 1, 239 51, 4 44,9 7,5

5.0 10, 20, 925 1, 177 49.1 41.0 14.0

4.8 9, 9 0, 937 1, 184 50, 9 42.1 12, 5

2.5 2.8 1, 062 1, 303 55, 0 46.7 3.3

5.0 5.5 1, 030 1.241 53, 7 45.5 6, 5

3.1 4.4 1, 048 1.296 52, 6 45.2 6, 0

5.2 10, 7 0, 929 1, 167 49, 5 41.2 13, 9

Table 1

Claims

P A T E N T S P R O C H E

Method for producing a grain-oriented

Electro-flat steel product with minimized

magnetic loss values, including the

steps

a) providing a flat electrical steel product, b) applying a layer of a phosphatic

Isolation solution on at least one surface of the electro-steel flat product and baking the applied layer,

After a first execution of the working step b), this operation b) is repeated at least once, so that from the layers successively applied to one another and baked on

Phosphate isolation solution

Insulation layer is obtained.

The method of claim 1, d a d u r c h

g e k e n c i n e s, d a s s applied in each step b)

Phosphate isolation solution a colloid

Component includes.

3. The method of claim 2, d a d u r c h

However, the colloid component is a colloidal silica.

4. Method according to one of the preceding claims, characterized in that the insulating solution aluminum and / or

Magnesium phosphate contains.

5. The method according to claim 1, wherein the isolation solution contains at least one pickling inhibitor and at least one wetting agent.

6. Method according to one of the preceding claims, characterized in that the isolation solution at least one

Colloid stabilizer (A) contains as an additive.

7. Method according to one of the preceding claims, wherein the stoving temperature is at least 300 ° C. during stoving carried out in the course of the working step b).

8. The method according to any one of the preceding claims, characterized in that in the course of the last repetition of B) carried out bake the baking temperature is at least 700 ° C.

9. Method according to one of the preceding claims, wherein, in the case of stoving carried out in the course of operation b), the stoving temperature is in each case at most 900 ° C., in each case.

10. Method according to one of the preceding claims, characterized in that the repeated execution of the working step b) of a treatment line takes place in which one of the number of successive lines in a line follows one another

Number of devices corresponding to the application and baking of the insulating solution are arranged, and that of the electric steel flat product to be coated in the continuous

Pass through.

11. Method according to one of the preceding claims, characterized in that in the case that the existing on the finished electro-steel flat product phosphatic

Insulation layer has a thickness D of up to 3 μπι, the specific layer density r of this phosphate insulation layer ^ 5 g / m ² , while at a thickness D of more than 3 μπι for the specific layer density r of the phosphatic

Insulation layer is: r [g / m ² ]> 3/5 ς / μπι / τα ² * D [μιτι].

12. The method of claim 11, d a d u r c h

In the case that the specific layer density r is that of the finished one

Electro-flat steel product existing phosphate insulation layer is 5.0 g / m ² , applies to the transmitted through the insulating layer tension Z:

Z [MPa]> 7/6 MPa * m ² / g * r [g / m ² ].

13. Grain-oriented electrical steel flat product which has a baked-on phosphatic insulation layer on at least one of its surfaces,

d a d u r c h e k e n e c i n e t, d a s s in the case that the thickness D of the phosphatic

Insulation layer ί 3 μπι is the specific

Layer density r of the phosphatic insulation layer is ^ 5 g / m ² , while at a thickness D> 3 ra for the specific layer density r of the phosphate insulation layer: r [g / m ² ]> 3/5 g ^ m / m ² * D [μιη].

14. Grain-oriented electro-steel flat product according to

Claim 13, d a d u r c h

that in the case that the specific layer density r of the phosphatic insulation layer is> 5.0 g / m ² , for the tensile stress Z transmitted through this layer:

Z [MPa]> 7/6 MPa * m ² / g * r [g / m ² ].

Grain-oriented electrical steel flat product according to one of claims 13 or 14, d a d u r c h

There is no difference between the steel substrate and the phosphatic

Insulation layer a forsterite layer is present.