DE1208504B - Process for the production of high-gloss aluminum sheets or strips - Google Patents

Description

Process for the production of high-gloss aluminum sheets or strips The present invention relates to a method for producing aluminum sheets or ribbons, which are used for the production of high-gloss objects can and which are particularly suitable for decorative anodic oxidation are equipped.

In order to produce objects with a decorative effect, the aluminum is often polished using chemical or electrochemical processes and then covered with an anodic cover layer . This vor'an is referred to as gloss anodization (smoothing with subsequent anodic oxidation).

The gloss and smoothness of the finished parts are greatly influenced by the structure of the aluminum. A heterogeneous structure, which, for example, contains compounds such as Al:, Fe, Mg, Si, etc. in addition to the aluminum mixed crystal, shows cloudy outer layers. A homogeneous structure in which the Beimen-ung n and alloying elements in aluminum, --e grid installed, ie are dissolved, is, however, very well suited for Glanzanodisierung.

For the production of strips or sheets for bright anodizing, the procedure has hitherto been such that round bars were solution-annealed. After an annealing period of about 10 hours, they were cooled to room temperature, inductively heated to about 400 ° C. , pressed into rails and these rails then rolled out into strips. This pre - to - is relatively cumbersome and leads to relatively high prices for semi-finished products.

Since semi-finished products with poor glossiness were achieved in the hot forming of cast ingots despite orange homogenization, attempts have already been made to cool them after solution annealing of the cast ingots, then to roll them warm and cold and the thus finished objects subdue with Abschreckbehandlun- - a abschliePenden Glühun- or last between a. z # lüliuii-- C Hicraus clearly shows that the experts were obviously of the opinion that it is impossible, starting from C- hot cast ingots, to direct the deformation in such a way that the cooled and deformed product actually has high lanceability.

It has now been found, surprisingly, that sheets or strips that are particularly capable of lancinating can be produced in a remarkably simple and economical manner by, after the known solution heat treatment of aluminum in the form of (cast) ingots, to about 500 # 'C quenched, rolled down to blank thickness in the temperature range of around 500 to 420'C, quenched the blanks to temperatures below around 200'C and then produced sheet metal or strips from them by cold rolling.

It is already known for the production of aluminum moldings with high gloss surfaces the casting of a homogenization treatment close below subject to the solidus temperature and then let it cool down. Apart from this, that the process according to the invention could not be inferred from this in any way is necessary this known method is another method when carrying out the method according to the invention superfluous intermediate annealing.

The invention is based on the knowledge that it is possible to produce high-gloss properties To obtain sheet metal in that certain temperature ranges are quickly overcome (2-stage quenching process), with a dwell time only in the one for rolling on Ile board thickness certain temperature interval is provided. This general The present invention is based on the idea. In fact, it has been shown that a sudden overcoming of certain temperature zones to high gloss Blegchen leads.

The solution heat treatment is advantageously carried out at temperatures of around 580 to 620 ° C, preferably at around 600 ° C. It is also possible for the quenching to take place in the blank rolling temperature range by means of water.

It has been found to be expedient to carry out the cold rolling to the final thickness without intermediate annealing and, if necessary, to set the desired final strength by means of a recovery annealing at 100 to 200.degree.

When quenching the cast ingot, the fastest possible and uniform cooling required over the entire cross-section. The most difficult this requirement can be achieved with round bars at which the relationship from surface. too- volume is very small; deterring them remains at the core relatively long warm.

Accordingly, the procedure is often to work with bars with a high surface-to-weight ratio, preferably with rolling bars or with bars with a weight-to-surface ratio of less than 2.2 kg / dm2. This ratio is achieved, for example, with an ingot that is 12 cm thick, 90 cm wide and 140 cm long.

Both aluminum with a degree of purity of 99.7 to 99.990% and low-weight, homogeneous aluminum alloys such as Mg-Al alloys with 0.2 to 2 % Mg are readily suitable for carrying out the process.

Claims (2)

Claims: 1. A process for the production of high-gloss aluminum sheets or strips or those made of low-alloy aluminum alloys, in particular with a small addition of magnesium, by solution annealing of aluminum bars, cooling and rolling, characterized in that after the known solution annealing of aluminum in the form of (casting -) Ingots, quenched to about 500'C, rolled down to blank thickness in the temperature range from about 500 to 420'C, quenched the blanks to temperatures below about 200'C and then cold-rolling them into sheets or strips. 2. The method according to claim 1, characterized in that the solution heat treatment at temperatures of about 580 to 620'C, preferably at about 600'C, is carried out. 3. The method according to claim 1 or 2, characterized in that the quenching takes place on the plate rolling temperature range by water. 4. The method according to any one of claims 1 to 3, characterized in that the cold rolling is carried out without intermediate annealing to the final thickness. # 5. The method according to any one of claims 1 to 4, characterized in that a final recovery annealing, preferably at 100 to 200'C, is carried out. Publications considered: German Auslegeschriften No. 1076 379, 1109 380.