DE2303416A1 - PROCESS FOR MANUFACTURING GRAIN ORIENTED COPPER SI STEEL - Google Patents

Description

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

The invention relates to a method for producing a grain-oriented Si steel, in which the steel is hot rolled down to strip thickness, subjected to a heat treatment for conditioning for the subsequent processing and the final structure annealing and then processed into a finished rolling mill product, as well as a Grain-oriented Si steel produced using the new process. The invention relates in particular to copper-containing silicon steels with approximately 2.2 to 4.0 % silicon.

309834/0798

The processing of such silicon steels to their final dimensions was previously only made with the help of two cold forming steps thought possible and carried out accordingly. Because silicon steels of the specified type in particular are used in electrical engineering, the microstructure depends on the cold deformation used and the magnetic properties influenced by this are of particular importance.

The invention is therefore based on the object of providing a method for producing a grain-oriented Si steel to create the silicon content specified above, which · while maintaining and even improving the magnetic Properties allowed to reduce the number of cold rolls to be used.

This object is achieved according to the invention in that warm treated and descaled Si steel of hot strip thickness with 0.24 to 0.75% by weight Cu in a single cold working process, directly cold-rolled to the final dimension and then is decarburized and normalized.

The invention is based on the guiding principle that the addition of certain quantities of copper, which must be precisely observed, is added to the amount of copper to be produced Si steel whose further processing from the original dimension of the hot strip to the desired one Final dimensions in just a single cold working step, preferably cold rolling, allowed. The deformation in just a single cold working process leads to a maintenance and improvement of the magnetic Properties of the product. Because of its good magnetic properties, that according to the invention is suitable Process manufactured steel in particular for use in such fields of electrical engineering in which the magnetic material properties are particularly important.

309834/0798

Because of the increased use of scrap "when melting of steels, copper traces can be detected in the Si steels produced today, although the trend is towards to minimize the levels of impurities.

The inventor has now found that a specific The critical amount of copper added to the Si content leads to a steel composition which, with the help of only one single cold working from the dimension of the hot strip to the final dimension of, for example, 0.524 to 1.3 mm can be rolled down and is excellent after annealing at 1177 ° C Has secondary crystallization and excellent grain growth. This will be for one only with oriented Si steel processed in a deformation step can obtain excellent magnetic properties or quality values. The opposite of conventional procedures shortened manufacturing cycle leads to considerable cost savings.

According to the invention, grain oriented Si steel is thereby made made that a Si steel with 0.24 to 0.75% Cu and the usual hot strip dimensions from 1.9 to 2.54 mm thick to facilitate the removal of scale and for conditioning for subsequent processing and that the final structure annealing is subjected to a heat treatment and then descaled. These steps are known per se and are carried out in a known manner, the decarburizing and structural annealing usually 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 during the final normalization. Thus, when applying of the method according to the invention only required a single cold working operation, while in the prior art

303834/0798

Technology has so far always assumed that for production Grain-oriented Si steels require two cold working steps. Made possible by the invention The saving of a cold working step and an intermediate annealing is based on the precise, and the copper content to be set, which, as has been found, has no adverse effects on the electrical or magnetic properties of the steel produced according to the invention.

A compilation of the magnetic properties of Steel compositions with various silicon and The copper content for which a conventional final normalization was carried out to decarburize all samples is the see table 1 below.

The results compiled in Table 1 show the magnetic properties of grain-oriented Si steels that were inductively melted in a vacuum, hot rolled from the cast block to the strip dimension, normalized and then cold rolled down to the final dimension. A final decarburization treatment was carried out before the structure annealing at 1177 ^{° G.}

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Table 1

Magnetic properties with different dimensions

to O HO CO

CD CO

2 0.64 • 3 mm 4th 0.47 5 mm 6th 0.56 7th mm 8th 0.27 9 mm 10 1 Cu (%) Core ver
desire
(W / 0.455
kg) at
15 KiIoG Perme
abili
activity
at
10 H. Core ver
desire
(W / 0.455
kg) at
15 KiIoG Perme
abili
activity
at
10 H. Core ν
desire
(W / 0, ·
kg) b
15 Ki: Perme
abili
activity
at
10 H. Core ver
desire
(W / 0.453
kg) at
15 KiIoG Perme
abili
activity
at
10 H. <0.01 WPP at.
15 KB μ at
10 H. WPP at
15 KB /did
10 H. sr-
^ 55
si
Log
I. /did
10 H. WPP at
15 BK. M at
10 H. 2.50 <0.01 1.80 1672 1.26 1620 WPP aj:
15 KB 155O 1.25 1460 2.72 <0.01 1.53 1751 0.97 1729 1-1.65. 1580 0.98 1511 5.00 <0.01 1.46 1722 1.05 1692 0.95 1529 1.19 1454 5.20 0.15 1.46 1720 1.00 1690 1.04 1540 1.20 1450 5.20 0.24 1.54 1590 1.52 1550 1.04 155O - - 2.50 0.40 1.41 1797 0.91 1824 1.04 1755 0.83 1612 2.50 0.42 1.51 1814 0.84 1835 0.75 1744 0.87 159a 2.50 0.59 1.55 1782 1.05 1810 0.77 1781 1.27 1456 2.75 0.59 1.56 1820 1.00 1842. 0.82 1845 0.55 1829 5.00 0.50 . 1.40 1752 0.94 1786 0.70 1788 0.61 1755 5.20 1.56 1660 1.04 L 1600 0.68 I7OO - - 1.04

VJl I

OJ CD CJ

■ Ρ Φ IQ

KN 4- CO VO S. O O OJ O CN KN O <y— CT \ V " V IA IA yy- KN KN KN CN V ν V KN V V ^ VD 4th Ο O 00 CO LfN KN CJN O O O IA O LfN LfN LA ν V ν V O V " V V " Ο KN Ο IA co LfN CO _O OO GO LN CO LN 4th O V CN VD ^ j- V " 4th ^} - 4 * KN V ν V " _ ^ · V V V (N 4- Ο CVI O _O IN O LN co VD VD VD O O O ν V V KN GO OJ Ο L (N VD 4th 4 " VD ω V KN LfN ζ ^ CVl KN V CO OO ν- ^ j- 4- 4 " CO V V " V ο ^ * V O LfN O OJ VO V " CT) LTN V CT> CO vD V CO VD OO O O _O V V V " LfN ON V LfN _O VO 4th (N CM GN VD KN ΓΝ [\. co LN 4th V 4th 4th 4 " V " ν V " V V " V " ^ " V0 _O 00 KN KN LfN OO KN V " CM V V KN CJN CO V " V " OJ LfN OJ V " V " IA CTN 0N V LN O _{O O} OJ O LfN LfN ω O O O O O O O O O V V ν U.N. LA O O CM _O IA Ο V OJ LN O LfN KN LfN LN O OJ KN CvJ OJ OJ KN

309834/0798

In the fourth row of headers in Table 1, the abbreviations designating the relevant magnetic material properties are also listed, starting with the third vertical column, in the manner mainly used in the English-speaking area. If anything is unclear, these abbreviations (WPP at 15 KB or Jj. At 10 H) are decisive.

As can be seen from Table 1, when the thickness is reduced from 1.3 to 0.73 mm, there is a reduction in core loss (watts per unit weight) for all silicon contents. At a thickness of 0.56 mm, the lowest core loss occurs at 2.75 % silicon. A permeability at 10 H of more than 1800 can also be achieved with the steel containing 2.75% silicon in all dimensions shown. Lower permeabilities can be achieved in the silicon contents of 2.5 and 3 O _5%. Thus, the measurement results contained in Table 1 show the favorable influence of copper on the development of the structure or 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 combined with 0.40 % copper results in improved cold rollability.

Overall, there is a considerably lower core loss (watts per unit weight) in connection with a considerably higher permeability noticeably at copper contents between 0.24 and 0.75 % , the most favorable results being obtained at around 0.4 % copper. The preferred ranges are from 2.5 to 3 ₅ O% Si and 0.3 to 0.5% Cu, the higher silicon-containing steel having a copper content in the lower part of the preferred range of copper.

309834/0798

, The grain-oriented Si-steel produced by this invention is completely "particularly suitable for use in the electrical industry and for the production of electrical components. He is taken from the Varmbandabmessung in a single cold working process to its final dimension and points to a structure-annealing at 1177 ⁰ C a Excellent secondary recrystallization and excellent grain growth, secondary recrystallization and grain growth lead to a product with excellent magnetic properties for a silicon steel produced by a single cold working step.

309834 / Π 798

Claims (3)

Patent claims 1. Process for the production of a grain-oriented Si steel, in which the steel is hot rolled down to strip thickness, a heat treatment for conditioning for the following Machining and the final structure annealing, descaled and then into a Walswerk finished product is processed, characterized in that heat-treated and descaled Si steel of hot strip thickness with 0.24 to 0.75% by weight Cu in a single cold working process directly to the final dimension cold-rolled and then decarburized and normalized. 2. The method according to claim 1, characterized in that that the steel contains 0.3 to 0.5 wt .-% Cu. 5. The method according to claim 1, characterized in that that the hot strip has a thickness of 1.90 to 2.54 mm and the final dimension has a thickness of 0.25 to 0.64 mm, 4-. Process according to Claim 1, characterized in that the steel contains 2.5 to 3.0% silicon and 0.3 to 0.5 % copper. 3 4/0798