LU86191A1 - PROCESS FOR THE CONTINUOUS MANUFACTURE OF A THIN COLD-ROLLED METAL STRIP - Google Patents

Description

* »'M BL-3621 / EM / EG C 2350/8512.

METALLURGICAL RESEARCH CENTER -% V

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CENTRUM V00R RESEARCH IN DE METALLURGIE, fO *

Nonprofit organization - :

Vereniging zonder winstoogmerk; in BRUXELLES, (Belgium). f mf- "‘ V * "’ --¾¾½

Process for the continuous production of a cold rolled thin metal strip.

The present invention relates to a process for the manufacture ιφ; · continuously of thin cold-rolled metal strips and * possibly annealed, in particular thin steel strips. %; / At present, cold-rolled thin strips are generally manufactured from hot-rolled strips which, after winding and cooling, are sent to the cold rolling mill where they are brought to the desired final thickness.

These hot rolled strips are themselves the result of a series of operations including the casting of liquid steel, either in ingots or continuously, the reheating of the ingots and the hot rolling.

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This way of proceeding involves numerous manipulations at the various stages of the manufacturing of the strips, as well as a reheating step before the hot rolling. These various operations require large installations, take a long time and consume very large amounts of energy. They therefore entail high costs which have repercussions on the price of the cold-rolled thin strips thus manufactured.

The object of the present invention is to remedy the drawbacks which have just been indicated, by proposing a process for the manufacture of cold-rolled thin strips which does not require costly installations. and bulky, which requires -sfif '·· only a limited execution time and which does not require high energy consumption.'% To this end, the process which is the subject of the present invention. 7

tion, for the continuous production of a metal strip .jS

. * 'thin cold rolled, is essentially characterized in that a metallic strip d * é-' JE is produced by continuous casting. appropriate thickness, in that the metal strip is rapidly cooled to a temperature suitable for cold rolling, and in the cold rolling of the metal strip thus cooled, in at least one rolling pass, up to to the desired final thickness.

According to a first implementation of the method of the invention, the cooled metal strip is pickled, before subjecting it to cold rolling.

Also according to the invention, the pickled and cold-rolled strip is subjected to continuous annealing under a non-oxidizing atmosphere.

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Still according to the invention, continuous annealing can be followed by a skin-pass rolling of the strip, with a reduction in thickness preferably less than 5%.

According to another particularly advantageous implementation of the process of the invention, the cooled metal strip is directly cold-rolled, without intermediate pickling, then it is immediately subjected to continuous annealing under a reducing atmosphere, so as to ensure reduction of the layer of surface oxides, and then to a hardening rolling (skin-pass).

In this regard, it has proven advantageous to carry out continuous annealing under a nitrogen atmosphere containing from 10% to 30% by volume of hydrogen.

The process of the invention makes it possible to continuously manufacture "thin cold-rolled metal strips, and optionally annealed, from a metal strip itself which is continuously cast therein. It is therefore important to take particular care to the quality of the surface of the strip continuously cast, in order to avoid surface defects liable to render cold-rolled strips useless.

The implementation of the method of the invention proves to be particularly advantageous because of the possibility of harmonizing the speed of continuous casting of the strip and the speed of movement of the strip in the continuous annealing furnace.

Thanks to the continuous nature of the process of the invention, the yield of the production of cold-rolled thin strips can be increased and the production times can be reduced.

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The method of the invention also makes it possible to omit the stage of production of hot-rolled strips, with in particular the heating of the ingots and the hot rolling of the strips. This results in a significant saving in installation costs, in manufacturing and storage costs of the strips, as well as in. summation of energy. The method also offers the possibility of adjusting the quality of the metal strips by adapting the conditions of the continuous annealing and the hardening rolling (skin-pass) according to the mechanical properties to be imparted to the said thin metal strip.

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Claims (8)

1. Process for the continuous production of a thin cold-rolled metal strip, characterized in that a metal strip of suitable thickness is produced by continuous casting, in that this metal strip is rapidly cooled to at a suitable temperature for cold rolling and in that the cold rolled metal strip thus cooled, in at least one rolling pass, to the desired final thickness. ^ 2. Method according to claim 1, characterized in that the cooled metal strip is pickled, before subjecting it to cold rolling. 3. Method according to claim 2, characterized in that after pickling and cold rolling, the metal strip is subjected to continuous annealing under a non-oxidizing atmosphere. 4. Method according to claim 3, characterized in that the annealed metal strip is subjected to a hardening rolling (skin-pass) with a thickness reduction rate preferably less than 5%. 5. Method according to claim 1, characterized in that cold rolled directly, without intermediate pickling, the cooled metal strip and in that immediately after cold rolling, the metal strip is successively subjected to continuous annealing under a reducing atmosphere then to a hardening rolling (skin-pass). f a. * * * ft # 6.- 6. Method according to claim 5, characterized in that a reducing atmosphere consisting of nitrogen containing from 10% to 30% by volume of hydrogen is used for continuous annealing. 7. Method according to either of claims 1 to 6 / characterized in that one adjusts the conditions of continuous annealing and / or rolling-hardening (skin-pass) according to the mechanical properties to be imparted to the said thin metal strip. 8. Method according to either of claims 1 to 1, characterized in that it is applied to the manufacture of thin steel strips. . \ \ V '/ · * · ..? ·? ? 'i &.