DE2303416C2 - Process for the production of a grain-oriented copper-containing Si steel - Google Patents

Description

According to the preamble of claim 1, the invention relates to a method for producing a grain-oriented copper-containing silicon steel with 2.2 to 4 wt .-% silicon, in which the steel is warm to strip thickness rolled down, a heat treatment for conditioning for the subsequent processing and that subjected to final structural annealing, and then descaled and cold-rolled in at least one operation will. Such a method is already known from DE-AS 11 17 624, with the help of the known Process the magnetic and electrical properties especially of a steel with 2.9 to 3.4 * silicon to be improved, which contains 0.05 to 0.3% copper as an impurity. The known procedure provides a multitude of hot forming steps with an exactly specified temperature profile. The cold rolling takes place in at least two cold tears if the sheet thickness is from 1.5 to 2 mm to approx. 0.3 mm is reduced.

From US-PS 32 87 184 a method is known with the help of a low level silicon steel with. 0.5 to 2% silicon and copper impurities of 0.02% given magnetic and electrical properties as otherwise only steels with 2.0 to 3.5% silicon or even 3 to 7% silicon have. This is at achieved by the known method in that the steel material is elongated before or after the cold forming Is subjected to heat treatment processes. The cold deformation itself is done in a single Work step carried out, whereby the material thickness is reduced from 1.9 to 2.16 mm to 0.3 to 0.63 mm. However, since the steel becomes increasingly brittle with increasing silicon content, i.e. H. less cold deformable, becomes and the difficulties in the heat treatment increase, this known method is not limited to medium as well Higher-alloy silicon steel can be used.

DE-PS 12 26 129 discloses a process for the production of single grain-oriented silicon steel known in which silicon steels with permissible copper contents of 0.01 to 0.03% in a single cold rolling step be rolled out to the final dimension. The copper contents, however, play a role in the DE-PS 12 26 129 described invention does not play a role as an influencing factor for the desired secondary crystal grain growth, since the aforementioned German patent only focuses on AIN as a grain growth inhibitor.

From "Stahl und Eisen" (1930), pages 1194 to 1197, it is known to use a steel with 1.5 to 4.0% silicon to achieve improved corrosion protection by adding copper.

From US-PS 31 59 511 is a method for improving the magnetic properties of a grain-oriented steel with 2 to 4% silicon and 0.01 to 0.03 or 0.09 to 0.13% copper is known. The intended Improvements are made through increased homogeneity of the steel as a result of reduced deposits in the grain boundaries, as well as through improved cone growth and grain orientation conditions achieved. On the other hand, however, it is necessary in the known method to strictly limit the aluminum content Limit 0.01 to 0.03%. To make a cold deformation in a single cold belt passage to additional requirements are placed on the heat treatment of the material before and after cold rolling posed. Such additional requirements lead to additional costs.

The invention is based on the object of developing a method of the type specified in the preamble of claim 1 so that grain-oriented silicon steel containing considerable amounts of copper can be processed into sheets with extremely good magnetic properties in a simple and inexpensive manner.
According to the wording of the characterizing part of claim 1, this object is achieved in that the copper content in the steel is set to 0.3 to 0.5% by weight and that the required cold deformation of the hot-rolled strip is from 1.9 to 2.54 mm to a final dimension between 0.25 and 0.64 mm is carried out in a single work step.

The technical progress that can be achieved with the aid of the invention is primarily to be seen in the fact that, despite the comparatively high copper contents particularly favorable electromagnetic properties in the manufactured

6 »material can be achieved. This results in very important cost advantages, on the one hand, because it contains more copper Scrap is significantly cheaper than scrap containing copper and, on the other hand, because the single-stage cold rolling is of course more economical than multi-stage cold rolling. The critical copper levels in the area from 0.3 to 0.5 <V, enable single-stage cold rolling and, what should be underlined, with cold rolling reductions, those carried out in the prior art only by multi-stage cold rolling with between the stages Intermediate anneals could be achieved.

According to the invention, grain size SI steel is produced in that a Si steel! with 0.3 to 0.5% Cu and the usual hot strip dimension of 1.9 to 2.54 mm thick to facilitate the removal of scale and for conditioning for the subsequent processing and the final texture annealing

Is subjected to heat treatment and then descaled. These steps are known per se and are carried out in a known manner, with the decarburizing and texture annealing usually being carried out simultaneously are executed. The annealed and descaled steel is then cut straight to its final dimension of 0.64 mm or less cold-rolled and then decarburized in the final normalization. Thus is at Use of the method according to the invention only requires a single cold working operation.

The single-stage cold rolling without intermediate annealing made possible by the invention is based on the exact Copper content to be maintained and set, which, as it turned out, does not have any unfavorable influences on the electrical and magnetic properties of the steel produced according to the invention.

A compilation of the magnetic properties of steel compositions with various Silicon and copper contents for which a conventional final annealing is carried out to decarburize all samples can be found in the following table.

The results compiled in the table show the magnetic properties of grain-oriented Si steels, which are inductively melted in a vacuum, rolled out warm from the cast block to the strip dimensions, normalized and then cold rolled down to the final dimension. Before texture annealing at 1177 ° C carried out a final decarburization treatment.

blackboard

1 2 0.64 mm 4th 1.672 0.47 mm 6th 0.36 mm G 0.27 mm 10 Cu (%) 3 Umma- Magne-
gnetistic tables
conduction induc-
lust P 1.5 tion B 8
(W / kg) (T) 1.731 5 Magne
tables
Induk
tion B 8
(T) 7th tfagne-
ische
nduk-
ion B 8
'T) 9 Magne
tables
induc-
ion B 8
[T) 2.50 <0.01 3,968 1.722 Umma-
gnetis-
insurance
lust P 1.5
(W / kg) 1.620 Umma-
gnetis-
ru ngs ver
lust pi, 5
(W / kg) 1,550 Umma-
gnetis-
insurance
lust P 1.5
(W / kg) 1,460 2.72 <0.01 2.932 1,720 2,777 1.729 2.204-
3,637 1,580 2.755 1.511 3.00 <0.01 3.218 1,590 2.138 1.692 2.05 1.529 2.161 1.454 3.20 <0.01 3.218 1.797 2.271 1.690 2,292 , 540 2.623 1,450 3.20 0.15 3.395 1,814 2.204 1,550 2,292 , 530 2.645 2.50 0.24 3.108 1,782 2.910 1,824 2,292 , 755 - 1.612 2.50 0.40 2,888 1,820 2.006 1,833 1.653 , 744 1,829 1,598 2.50 0.42 3.417 1.752 1,851 1,810 1.697 , 781 1.918 1.456 gerr 2.75 0.39 3,439 1.660 2,314 1,842 1.807 , 845 2,799 1,829 mgs 3.00 0.39 3.086 1,768 2.204 1,786 1.543 , 788 1,212 1,755 • ο
C. 3.20 0.30 2.998 1,825 2.072 1,600 1,499 , 700 1,345 tzz
ω 2.50 0.58 3,549 1,799 2,292 1,830 2,292 , 801 - 1.737 2.75 0.59 3.086 1.471 2.381 1,818 1.609 , 773 1.477 1.534 3.00 0.59 2.821 1,650 2.05 1,832 1.631 , 680 2.222 1.508 2.50 0.81 4,828 1.430 1,874 1,490 1.764 , 475 2.204 1.416 3.20 0.75 2.954 1.476 3.527 1,550 3.13 , 480 3.306 1,440 2.50 1.00 5.136 1,470 2.645 1.406 2,293 , 405 1,829 , 390 2.75 1.00 4,298 4.32 1.424 3.725 , 408 3.483 , 390 3.00 1.00 4,365 3,990 1.434 3,549 , 400 3.417 1,392 3.704 3.527 3.373

As can be seen from the table, the decrease in thickness from 0.64 to 0.36 mm occurs for all silicon contents a reduction in the magnetic reversal loss (W / kg). At a thickness of 0.27 mm, the lowest loss at 2.75% silicon. A magnetic induction B8 of more than 1.8 T can also occur at The steel containing 2.75% silicon can be achieved in all dimensions shown. Lower magnetic Inductions are achieved at the Slllclum levels of 2.5 and 3.0%. Thus the In the panel show the measurement results contained the favorable influence of copper on the development of the texture of SI steels, which have been brought to the final dimensions by means of a one-step process. It is believed, that a low silicon content in connection with 0.40% copper leads to an improved cold-rollability.

Overall, there is a considerably lower magnetic reversal loss in connection with a considerable higher magnetic induction is already noticeable at copper contents between 0.24 and 0.75% however, best results are obtained with about 0.4% copper. The most favorable areas are thus cherished between 2.5 to 3.0% Sl and 0.3 to 0.5% Cu, with the higher silver-containing steels having a copper content in the should have the lower part of the specified copper range.

The grain-oriented Si steel produced according to the invention is particularly suitable for use in Electrical industry and for the production of electrotechnical components. It is determined by the hot strip dimension brought to its final dimensions in a single cold working process and shows after a structural annealing excellent secondary recrystallization and excellent grain growth at 1177 ° C. Secondary recrystallization and grain growth result in a product with for one by one Cold working step made silicon steel excellent magnetic properties.

Claims (2)

Patent claims: 1. Process for producing a grain-oriented, copper-containing silicon steel with 2.2 to 4% by weight silicon, in which the steel is hot rolled down to strip thickness, a heat treatment subjected to conditioning for the subsequent processing and the final flanging annealing, is descaled and cold-rolled in at least one operation, characterized in that the Kapfer content in the steel is set to 0.3 to 0.5 wt .-% and that the required cold deformation of the hot-rolled strip from 1.9 to 2.54 mm to a final dimension between 0.25 and 0.64 mm in a single Operation is carried out. 2. The method according to claim 1, characterized in that the silicon content in the steel to 2.5 to 3.0 Wt .-% is set.