DE1433761A1 - Process for the annealing of upright coils wound from iron or sheet steel strips - Google Patents

Description

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Dipl.-Ing. Walter Meissner Dipl.-Ing. Herbert Tischer

BERLIN 33 CGrunewald}, Herbertstrasse 22 MUNICH

Fernepreoher: 07 72 37 - Wire word: Invention Berlin AL OO HCA Poeteoheoc account: W. Meissner, Berlin-West 1S2 82 I "TuO / U Bank account: W. MeleaaaLBerllner Bank A.-G., Depka 36,

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Hanneemann Aktiengesellschaft, Düsseldorf, Mannesmannufer 1b

Process for annealing from iron or steel sheet » ribbons wrapped upright collars

The invention relates to a method for annealing from Λ

Iron or sheet steel bands wound upright Bonds, with the purpose of removing carbon and / or Nitrogen between the spacers between the separated tape windings hydrogen or hydrogen-containing gas is passed through

As is known, carbon and nitrogen exert a strong influence on the properties of sheet metal as accompanying elements, especially on deep-drawing qualities. For specific uses it is desirable that their content in the sheet is as low as possible or that they are even completely removed from it »Provided When the steel is melted, the required analysis cannot be adhered to, is a change in the chemical Composition possible through an annealing treatment of the sheets, which usually takes a long time. An example is the development cited. Although processes are known today, steels with a low nitrogen content are already used in the melt flow it becomes even more economical in many cases

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his ,, high-quality sheets, e.g. made of normal Thomasstahl, subsequently by annealing at relatively low! temperatures

Ptir special purposes, e.g. for making τοη enamelled Sheet metal, a particularly low carbon content is essential. «This cannot be achieved when melting steel will. In this case, too, there is no long-term annealing to bypass ο

It has now been proposed to carry out such annealing treatments using the so-called "open coil annealing" method. In this process, the sheets for annealing are loosely wound so that there is an open gap of around 1 mm between the individual turns of the bundle of ice. remains, through which the reducing® gas - brought into a circuit with the help of a fan - flows through during the glowing process and can thus react with d @ a sheet metal. The production of the winding distances is reached when wrapping from dense to loose waistband wrapping a Uylonfadens which is removed before annealing, or by wrapping a double twisted wire, this method has di © following Maehteile "The apparatus for making ά © 2? open ^ or _o nacii of the annealing and dense bundles are very expensive, since the bundle has to be _{wrapped in a vertical position e} lushermore it has been found in the case of% Burehführisng des Y®v ^ fahraas that edges can easily be damaged and v / after all, when wilting back --worn loose to a capable thawed waistband after the annealing treatment great

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-3 difficulties arise

According to the invention, these disadvantages are eliminated by that powdery substances are used as spacers, which do not sinter onto the strip surface during annealing and whose grain size distribution is less than 0.5 mm, preferably between 0.3 and 0.05 mm, and that the thickness of the Powder layer is about twice as large as the largest of the in the grain class it contains

The further features of the invention are suitable for this purpose powdered minerals or slag, e.g. »Thomas flour or also powdery getter substances, e.g. aluminum-containing iron powder *

In order to maintain a small, fixed distance between the individual sheet metal layers even during annealing, during The normal horizontal wrapping of the tape is a thin layer of powder as an intermediate layer in the turns of the federal government · The grain class distribution of the powder is chosen so that the annealing gas can pass through and with the " Sheet metal can react · The mechanical equipment for winding coils with such intermediate layers are incomparably cheaper than the above-mentioned machines for producing the so-called open coils · Furthermore, it turned out to be The circulation of the hydrogen unexpectedly was so good that the ventilators necessary in the case of open leagues can be omitted. A special part of the goal of the new procedure compared to the open bundle procedure is given by that the wrapping, in particular the wrapping back to

Shippable bundle, can be done under a strong train and thus the known error possibilities are eliminated «you Reversing from the open to the light covenant is part of the process Open collars only possible with the use of very complex additional mechanical equipment, while the removal of the spacing powder after annealing is possible with the simplest of devices with the present method.

In some types of production, it is common to insert layers of oxide powder between the turns of coils »and» to prevent the sheet metal layers from welding together during the subsequent annealing treatments , so that a circulation of the hydrogen almost is impossible * Further silylated in the manufacture of sheets Ύοη oxides used as a cover during annealing, but also for a different purpose, namely to produce the so-called grain-oriented siliconized sheets ·

The use of getters to remove H ₂ O ₉ H ₂ S ₉

HHj and CH. in the annealing of sheet metal (in particular of siliconized sheet metal) in hydrogen has already been proposed several times. Metallic calcium were used as getter substances and calcium carbide as well as titanium and nickel (also in compounds) specified

The use of such substances in large-scale sheet metal production, however, could not be introduced · The reason

this is likely to be found in the fact that the powders are either arranged separately in the furnace or in boxes when they are glowing were scattered between the horizontally lying panels. In such arrangements, however, is also when using a Getters necessary circulation of the hydrogen not given. However, if such powdery getters according to the invention are used as a spacer intermediate layer in coils perpendicular to a strip edge, then even without the use of Fans provide the necessary circulation of hydrogen

In addition, the amount of hydrogen can be significantly reduced compared to the previous process

Another advantage is that when the hydrogen flows through, there is no vortex formation, and thus no vortex formation do not form stagnant gas areas · The gas flows slowly through the powder layer and affects all parts the belt surface evenly.

The process is explained in more detail in the following examples)

i example 1

Band quality in the initial state: unquenched Thomasstahl,

0.0104 1 » N and 0.034 i> 0

Band thickness 0.85 mm Intermediate layer powder t aluminized iron powder (3 i » Al), Grain classes from 0.1 to 0.4 mm Powder layer thickness about 0.8 mm Annealing temperature t 55O ° C Glowing lasts 20 hours Inert gas pure hydrogen Band analysis after annealing treatment: 0.0000 # N and 0.019 ί> Ο

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Example 2

Band quality in the initial state J unrestrained oxygen uptake

blow steel »0.0032 £ Ii and 0.055 i» C

Belt thickness t 1.1 mm

Interlayer powder aluminized iron powder (9 ^ Al),

Grain classes from 0.1 to 0.4 mm

Powder layer thickness: about 0.8 mm

Annealing temperature t 720 ⁰ C

Annealing time: 5 hours

Protective gas: pure hydrogen

Strip analysis after the annealing treatment: 0.0000 i » IT and 0.003 1 ° C

Example 3

Bad quality in the initial state of unquenched Thomasstahl,

$ 0.0140> ii and $ 0.090 c

Ribbon thickness 1.0 mm

Interlayer powder: aluminized iron powder (3 fl Al),

Grain classes 0.1 to 0.4 mm

Powder layer thickness about 0.8 mm

Annealing temperature: 55O ⁰ C

Glowing lasts 40 hours

Protective gas: contains hydrogen © β protective gas

Band analysis after the annealing treatment ι $ 0.0010> N and $ 0.015 C

In addition to the getter effect, the Al-containing egg powder, which were produced by atomizing the liquid alloy with the help of press water, in addition to being affordable the advantage that they are always present on their surface because of the Can not sinter the alumina skin on the belt surface · They are easy to apply and after glowing

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easy to remove and can be reused very often «

Thomas flour with grain classes below 0.4 mm, especially between 0.1 and 0.03 mm, proven

Example 4 Dand quality in the initial state »

a) unquenched Thomasstahl

b) untouched oxygen inflation steel (LD steel)

Ribbon thickness 1.0 mm a) 0.0110 # S and 0.046 # C

b) 0.0037 1 · N and 0.033 1> 0

Intermediate layer powder »Thomas slag, Grain classes from 0.1 to 0.4 mm Powder layer thickness χ about 0.8 mm Annealing temperature: 720 ° C Glowing lasts 5 hours Protective gas hydrogen Strip analyzes after the annealing treatment ι

d 0.002 £ C d 0.002 1 ° C

0.0004 t H and 0.002 £ C 0.0003 £ N and 0.002 1 ° C

Patent claims:

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Claims (1)

Patent application 1 · Method of annealing τοη from iron or sheet steel strips wrapped upright collars, with carbon and / or nitrogen wiping for the purpose of removing clay hydrogen or hydrogen-containing gas is passed through by means of spacers separated from one another in ribbon windings. is characterized in that pulverulent substances are used as spacers, which are not consumed during annealing sinter the belt surface and its grain distribution Area below 0.5 mm, gate pull between 0.3 and 0.05 mm comprises, and that the thickness of the powder layer is approximately twice is as large as the largest of the grain classes it contains 2 «Process according to claim 1, characterized by the use of clay powder-shaped minerals or slag, s« B » Thomas flour ο «like. 3. The method according to claim 1, characterized by the use of clay powdery getter substances, for example aluminum-containing iron powders. BATH ORIGINAL 80981 1/0270