DE1097233B - Process for the production of a gloss anodizable composite material from aluminum alloys - Google Patents

Description

Process for the production of a glossy anodized composite material made of aluminum alloys For various purposes, e.g. B. for the production of Hubcaps, bumpers and trim strips for automobiles, aluminum sheets are desirable, which have high mechanical strength and high hardness and at the same time are gloss anodized, d. H. after a chemical or electrolytic polishing treatment and a subsequent anodic oxidation (anodizing) have a high gloss. Only such aluminum sheets could be used with chrome-plated hubcaps and bumpers Successfully competing irons.

The normal, hardenable aluminum alloys (solution annealing, quenching and aging at room or elevated temperature), e.g. B. A1 Mg Si 1, Al CuMg 1, Al CuMg 2 and A1 Zn Mg 3, have high mechanical strengths, but the surface quality achieved by bright anodizing does not meet the requirements.

Some processors want glossy anodized sheets, and not only have high mechanical strength, good hardness and good gloss anodisability, but also in the condition hardened by heat treatment are so well deformable that they can be z. B. to hubcaps or Let the bumpers press. However, the above alloys are hardened Condition insufficiently deformable for such a purpose.

In the case of the aluminum alloys which can only be hardened by cold working, e.g. AlMg, the higher strength is due to the increased content of alloy components (Mg for AlMg) bought at the expense of gloss anodisability and deformability.

It is also known to use aluminum alloys for items where it depends on a high gloss, with pure aluminum, which is best anodized with a gloss finish lets to plate. However, these composite bodies do not have the strength of Aluminum alloys, and in particular the hardness of the cladding layer is after the heat treatment too little for the purposes already mentioned. It was because of that already proposed, the ultra-pure aluminum for the cladding layer, high-purity metals to be added in such an amount that they are in the material to be plated even under tempering conditions remain absorbed in solid solution. The strength is compared to that only composite body clad with pure aluminum heightened; however, it does not achieve the values of heat-treatable aluminum alloys, since the Alloys with additives that always remain in solution cannot be hardened. In the Heat treatment to harden the core material then decreases the hardness of the cladding material strong again.

It is also a heat treatment hardenable AlMgSi alloy known on the basis of pure aluminum, which achieves high mechanical strength values and can be easily polished anodized. However, this material is used in solution heat treatment coarse-grained, which is undesirable in a subsequent deformation; he is suitable therefore not for the manufacture of hubcaps and bumpers for motor vehicles.

The invention now relates to the production of bright anodized aluminum sheets, the at the same time high mechanical strength, good deformability by heat treatment cured state and a fine-grained surface on the shiny side own. It consists in the use of a hardenable, from an AlMgSi alloy made from commercially available pure aluminum with 0.3 up to 0.7% Mg and 0.3 to 0.7% Si in the form of a rolling bar as the base material and an anodized one made of aluminum with a purity of over 99.85% produced AlMgSi alloy with 0.3 to 0.7% Mg and 0.3 to 0.7% Si as a cladding material, the rolling billet in a known manner after hot rolling rolled down to the finished thickness and finally hardened by heat treatment will.

Both in the case of the core alloy (the alloy of the rolling bar) as well as the clad layer is an AlMgSi alloy with lower Content of Mg and Si than in the normal AlMgSi alloys, which are up to 1.4% Mg, up to 1.2% Si and up to 1.0% Mn. In other words, it is In both cases it is a relatively low-alloy aluminum, but that in the case of the Heat treatment of the composite body maintains high yield strength, tensile strength and hardness and still remains easily deformable.

A low-alloy AlMgSi alloy based on A1 of one purity of over 99.85% becomes as coarse-grained during annealing as the normal-alloyed AlMgSi based on pure aluminum. Surprisingly, it has now been shown that both this low-alloy cladding material and the low-alloy core material at the Solution heat treatment after roll cladding finely and uniformly recrystallized; it there seems to be a germination effect from the welded zone between cladding material and To go out of core material.

The thickness of the clad layer after finish rolling can be about 200/0 the total thickness of the sheet. It is of course possible in the frame of the method according to the invention, both sides of the aluminum sheet can be polished anodized to make by in its manufacture both sides of the billet with a plate made of low-alloy AlMgSi based on Al 99.85% or more.

Example A rolling ingot with a thickness of 110 mm made from a commercially available Pure aluminum made aluminum alloy with 0.40 /, Mg and 0.60 / "Si covered with a 25 mm thick plate made of an aluminum alloy, which is made of pure aluminum 99.99% with an addition of 0.4010 Mg and 0.6% Si. The one with The bar covered with the plating plate is heated to 420 ° C. for 8 hours and then raised hot rolled about 7 mm thick. After this treatment, the base and cladding material are intimately connected, so that the desired final strength of z. B. 1 mm can be further cold rolled. At final thickness, the material undergoes a solution heat treatment subjected and quenched at 520 ° C.

After aging (aging) for 3 days at room temperature, the material shows the following strength values: Yield strength Tensile strength Elongation Brinell hardness a 0.2 (kg / mm2) s B (kg / mm2) 810 (o / o) kg / mm 2 8 to 9 19 to 21 30 to 25 50 to 55 In this condition it is very malleable and shows a deep-drawing ratio of more than 1: 2; the deformability corresponds to that of soft pure aluminum, although the deformation work to be applied is higher.

If the material, which has been aged for 3 days at room temperature (intermediate storage), is tempered at 140 ° C, the following strengths can be achieved: Yield strength Tensile strength Elongation Brinell hardness a 0.2 (kg / mm2) a B (kg / mm2) 810 (° / o) kg / mm2 18 to 20 I 24 to 27 I 22 to 18 I 75 to 80 Tempering at 160 ° C without intermediate storage after quenching achieves the following strength values: Yield strength Tensile strength Elongation Brinell hardness s 0.2 (kg / mm2) a B (kg / mm2) 810 (o / o) kg / mm2 28 to 32 32 to 36 20 to 15 90 to 100 In this state, the deep-drawing ratio is about 1: 1.9; that is, the deformability is very high compared to the strength achieved. It can be z. B. by pressing - or deep-drawing - from the material described above with a hardness between 90 and 100 kg / = n2 produce hub caps for automobiles that can successfully compete with the hub caps made of chrome-plated sheet steel.

Depending on the intended degree of deformation, the sheets are either only aged at room temperature or, if necessary, after intermediate storage cured at room temperature, warm.

The hardened,. largely homogeneous material produced Drawn parts can then be subjected to the deformation process by means of the usual Baths shine chemically or electrolytically and anodize, whereby the achievable shine depends on the purity of the metal used for the cladding material (Fe content) as well as the solution annealing temperature.

Claims (1)

PATENT CLAIM: Use of an AlMgSi alloy made from commercially available pure aluminum with 0.3 to 0.7% Mg and 0.3 to 0.7% Si in the form of a rolling ingot as the base material and which can be hardened by heat treatment anodized AlMgSi alloy with 0.3 to 0.7% Mg: and 0.3 to 0.7% Si as a cladding material for production, made from aluminum with a purity of over 99.85 "/, a glanzeloxierbaren composite material, the rolling ingot wobei- in a known manner after the hot rolling to finished thickness rolled down and is finally cured by heat treatment contemplated publications: German Patent No. 748,943; French Patent specification No. 1036 081st...