EP0246186B1 - Aluminium alloy products with uniform grey, light-fast surfaces, and process for their production - Google Patents

Aluminium alloy products with uniform grey, light-fast surfaces, and process for their production Download PDF

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Publication number
EP0246186B1
EP0246186B1 EP87810276A EP87810276A EP0246186B1 EP 0246186 B1 EP0246186 B1 EP 0246186B1 EP 87810276 A EP87810276 A EP 87810276A EP 87810276 A EP87810276 A EP 87810276A EP 0246186 B1 EP0246186 B1 EP 0246186B1
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Prior art keywords
iron
manganese
alloy
light
electrolyte
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German (de)
French (fr)
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EP0246186A1 (en
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Jürgen Timm
Jean-François Paulet
Jörg Maier
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3A Composites International AG
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Alusuisse Lonza Services Ltd
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    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22F—CHANGING THE PHYSICAL STRUCTURE OF NON-FERROUS METALS AND NON-FERROUS ALLOYS
    • C22F1/00—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working
    • C22F1/04—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working of aluminium or alloys based thereon
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C21/00—Alloys based on aluminium
    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
    • C25D11/00—Electrolytic coating by surface reaction, i.e. forming conversion layers
    • C25D11/02—Anodisation
    • C25D11/04—Anodisation of aluminium or alloys based thereon
    • C25D11/14—Producing integrally coloured layers

Definitions

  • the invention relates to aluminum alloy products in the form of extruded profiles or cold rolled sheets with a uniformly gray, lightfast surface and a light reflectivity of at most 50% obtained by anodic oxidation in an electrolyte.
  • the invention also relates to a method for producing these products.
  • the two-stage electrolytic dyeing processes represent a diverse group.
  • an oxide layer of approximately 20 11 m thick is produced in a sulfuric acid or sulfuric acid / oxalic acid bath by means of direct current with a density of 100 to 200 Alm 2 .
  • alternating current with a density of 10 to 150 A / m 2 is deposited from metal salt solutions of suitable composition to adhere metal compounds to the pore base of the oxide layer, thereby producing a permanent and lightfast color.
  • Another group of processes for producing lightfast gray colorations consists of single-stage color anodization, in which oxide layers with a natural intrinsic color are produced in a special electrolyte by means of direct current of 70 to 800 Alm 2 density.
  • the electrolyte that determines the color tone consists of organic acids, optionally with additions of sulfuric acid.
  • Aluminum alloys of the types AIMn, AIMg and AIMSi are mostly used as materials.
  • decorative gray tones can also be produced with standard anodizing processes. These inexpensive and widespread anodizing processes work with direct current from 80 to 300 Alm 2 density and use a sulfuric acid electrolyte, often with small additions of carboxylic acids.
  • a known aluminum alloy contains 4.5% silicon and 0.5% magnesium. With a current density of 150 Alm 2 , an oxide layer with a thickness of approximately 18 pm is formed after 40 minutes, which has a medium-gray intrinsic color. The light reflectivity, as a measure of the gray tone, is 20%. After an oxidation time of 60 minutes, the oxide layer measures 27 pm and has a dark gray inherent color with 13% light reflectivity. For this purpose, the reflectivity was determined using a LANGE UME 1-LFE 1-1 measuring device.
  • FR-A-2 091 651 is an aluminum alloy with 0.05 to 0.15% copper, 0.5 to 0.7% iron, 0.15 to 0.3% silicon, 0.3 to 0.6% Manganese known, with which a beige color can be produced by anodic oxidation.
  • FR-A-2 119 077 discloses a method in which objects made of an aluminum alloy are anodically oxidized with 1 to 3% iron to produce a greyish silvery hue.
  • the inventors have set themselves the task of creating aluminum alloy products of the type mentioned at the outset and a process for their production which, with the usual anodizing processes, without an additional coloring step, provide a uniform, structure-free, lightfast, gray surface of at most 50% light reflectivity enabled. It should be possible to produce a wide range of shades of gray with a constant alloy composition.
  • the object is achieved according to the invention in that the alloy of 1.20 to 1.60% iron and 0.25 to 0.55% manganese with a weight ratio of iron to manganese between 2.8 and 5 to 0.20% silicon , up to 0.30% copper, up to 5% magnesium, up to 0.10% chromium, up to 2% zinc, up to 0.25% zirconium, up to 0.10% titanium, the rest aluminum and altogether up to 0.50% other elements, whereby the light reflectivity with constant alloy composition is adjustable between 8 and 45% for oxide layers of 5 to 30 ⁇ m and less than 30% for oxide layers of 10 pm.
  • Within the scope of the invention is also a method for producing these aluminum alloy products with a uniformly gray, light-fast surface and a light reflectivity of at most 50% by anodic oxidation in an electrolyte without additional dyeing tub, which is characterized in that when an alloy is processed, there is from 1.20 to 1.60% iron and 0.25 to 0.55% manganese with a weight ratio of iron to manganese between 2.8 and 5 and up to 0.20% silicon, up to 0.30% copper, up to 5% magnesium, up to 0.10% chromium, up to 2% zinc, up to 0.25% zirconium, up to 0.10% titanium, rest of aluminum and a total of up to 0.50% of other elements from the casting to the product, all treatment temperatures are kept below 560 ° C and the residence time in the temperature range between 540 and 560 ° C is a maximum of 4 hours.
  • All treatment temperatures are preferably selected in the lowest possible range for processing and the residence time at temperatures above 300 ° C. is kept as short as possible.
  • An advantageous embodiment consists in carrying out the anodic oxidation using direct current in a sulfuric acid electrolyte with 10 to 25% by weight sulfuric acid and up to 5% carboxylic acids.
  • the surface of the aluminum workpieces can be pretreated by grinding, brushing, polishing, etching, glossing and the like.
  • a rectangular strand of 320 x 1080 mm 2 cross section was cast from an alloy with 1.42% iron, 0.44% manganese, 0.06% silicon and the rest aluminum with 0.07% impurities.
  • the conventionally cast ingot was milled 10 mm on both sides. This could be dispensed with when using hot top or magnetic field molds.
  • the ingot was then heated to 520 ° C and fed to a hot rolling stand without holding time and rolled into a sheet 8 mm thick.
  • the plate emerging at a temperature of 450 ° C. was passed through a water box and cold-rolled to a thickness of 1.0 mm. After a final annealing of 3 hours at 320 ° C., the sheet had a tensile strength R m of 142 MPa, a yield strength R p0.2 of 104 MPa and an elongation A 5 of 40%.
  • Sheets of 980 x 980 mm 2 were anodized in an electrolyte.
  • the bath contained 180 g sulfuric acid and 10 g oxalic acid per liter.
  • the density of the direct current was 150 A / m 2 .
  • the oxide layer of a sheet anodized for 20 minutes measures 10 pm.
  • the sheet shows a uniform, medium gray color over the entire surface.
  • the light reflectivity determined with the LANGE UME 1-LFE 1 measuring device is 21%.
  • Sheets oxidized for 40 minutes have an oxide layer 20 ⁇ m thick.
  • the light reflectivity of the even dark gray surface is 12%.
  • a round bolt with a diameter of 200 mm was cast from an alloy with 1.45% iron, 0.43% manganese, 0.15% zirconium, 0.05% silicon and the rest aluminum with 0.04% impurities.
  • the bolt was turned over 2 mm deep and quickly heated to 490 ° C for extrusion and pressed into 3 profiles with 140 mm 2 cross-sectional area each without holding time.
  • the strands having press weld seams emerged from the die at a temperature of 540 ° C. and were cooled with moving air. Tensile tests showed a tensile strength R m of 160 MPa and a yield strength R p0.2 of 85 MPa.
  • a round bolt with a diameter of 160 mm was cast from an alloy with 1.48% iron, 0.40% manganese, 1.2% magnesium, 0.05% silicon and the rest aluminum with 0.04% impurities.
  • the bolt was turned over 3 mm deep and quickly heated to 380 ° C for extrusion and pressed after a holding time of one hour to a rectangular profile with a cross section of 4 x 30 mm 2 at a speed of 16 m / minute.
  • the strand emerged from the die at a temperature of 460 ° C. and was cooled in air.
  • the tensile strength R m was 215 MPa, the yield strength R p0.2 106 MPa and the elongation at break A 5 21%. After 3% stretching, an R m of 220 MPa, an R p0.2 of 173 MPa and an A 5 of 19% were measured.
  • Strand sections were anodized in a bath with 180 g sulfuric acid and 10 g oxalic acid per liter at a direct current with a density of 150 A / m 2 . After 25 minutes of treatment, the oxide layer measured 12 pm. The reflectivity is 18%.
  • Extruded profiles from Example 2 were anodized at 25 ° C. in an aqueous bath with 75 g sulfosalicylic acid, 50 g tartaric acid and 5 g sulfuric acid per liter at a direct current with a density of 150 A / m 2 . After 25 minutes of treatment, the oxide layer thickness was 9 ⁇ m. The reflectivity of the dark gray surface is 12%.
  • Extruded profiles from Example 2 were anodized at 20 ° C. in a bath with 160 g sulfuric acid and 20 g glycerol per liter for 40 minutes at a direct current density of 150 A / m 2 .
  • the thickness of the resulting oxide layer is 22 pm, the reflectivity 11%.
  • Extruded profiles from Example 2 were anodized at 20 ° C. in a bath with 200 g sulfuric acid per liter for 20 minutes.
  • the current density alternated with a frequency of 25 Hz between the two devisx 150 and 200 Alm 2 , each with a dwell time of 20 ms.
  • the resulting oxide layer measures 12 pm and has a reflectivity of 16%.

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Description

Die Erfindung betrifft Aluminiumlegierungs-Erzeugnisse in Form von Strangpressprofilen oder Kaltwalzblechen mit gleichmässig grauer, lichtechter Oberfläche und einer durch anodische Oxidation in einem Elektrolyt erhaltenen Lichtreflektivität von höchstens 50%. Zudem erfasst die Erfindung ein Verfahren zum Herstellen dieser Erzeugnisse.The invention relates to aluminum alloy products in the form of extruded profiles or cold rolled sheets with a uniformly gray, lightfast surface and a light reflectivity of at most 50% obtained by anodic oxidation in an electrolyte. The invention also relates to a method for producing these products.

Zur Erzielung dekorativer Graufärbung von Aluminiumlegierungs-Erzeugnissen sind diverse Verfahren bekannt, welche von der anodischen Oxidation ausgehen und keine zusätzliche adsorptive Färbung benötigen. Der resultierende Farbton wird durch mehrere Verfahrensparameter bestimmt, insbesondere durch die Elektrolytzusammensetzung, die angelegte Spannung, die Stromart, -dichte und -dauer sowie durch die Legierungszusammensetzung.Various processes are known for achieving decorative gray coloring of aluminum alloy products, which proceed from the anodic oxidation and do not require any additional adsorptive coloring. The resulting hue is determined by several process parameters, in particular by the electrolyte composition, the applied voltage, the current type, density and duration as well as by the alloy composition.

Eine vielfältige Gruppe stellen die zweistufigen elektrolytischen Färbeverfahren dar. Dabei wird in einer ersten Stufe in einem Schwefelsäure- oder Schwefelsäure-/Oxalsäurebad mittels Gleichstrom mit einer Dichte von 100 bis 200 Alm2 eine Oxidschicht von etwa 20 11m Dicke erzeugt. Anschliessend wird in einer zweiten Stufe durch Wechselstrom mit einer Dichte von 10 bis 150 A/ m2 aus Metallsalzlösungen geeigneter Zusammensetzung Metallverbindungen am Porengrund der Oxidschicht festhaftend abgeschieden und damit eine dauerhafte und lichtechte Färbung erzeugt.The two-stage electrolytic dyeing processes represent a diverse group. In a first stage, an oxide layer of approximately 20 11 m thick is produced in a sulfuric acid or sulfuric acid / oxalic acid bath by means of direct current with a density of 100 to 200 Alm 2 . Subsequently, in a second stage, alternating current with a density of 10 to 150 A / m 2 is deposited from metal salt solutions of suitable composition to adhere metal compounds to the pore base of the oxide layer, thereby producing a permanent and lightfast color.

Eine weitere Gruppe von Verfahren zur Erzeugung lichtechter Graufärbungen besteht in der einstufigen Farbanodisation, bei welcher mittels Gleichstrom von 70 bis 800 Alm2 Dichte in einem Spezialelektrolyten Oxidschichten mit natürlicher Eigenfärbung erzeugt werden. Der nebst der Legierungszusammensetzung den Farbton bestimmende Elektrolyt besteht aus organischen Säuren, gegebenenfalls mit Zusätzen an Schwefelsäure. Als Werkstoffe werden zumeist Aluminiumlegierungen vom Typ AIMn, AIMg und AIMSi eingesetzt.Another group of processes for producing lightfast gray colorations consists of single-stage color anodization, in which oxide layers with a natural intrinsic color are produced in a special electrolyte by means of direct current of 70 to 800 Alm 2 density. In addition to the alloy composition, the electrolyte that determines the color tone consists of organic acids, optionally with additions of sulfuric acid. Aluminum alloys of the types AIMn, AIMg and AIMSi are mostly used as materials.

Bei ausgesuchten Legierungen und nach Einhaltung spezieller Halbzeugfertigungsvorschriften lassen sich auch mit Standard-Anodisierverfahren dekorative Grautöne erzeugen. Diese kostengünstigen und weitverbreiteten Anodisierverfahren arbeiten mit Gleichstrom von 80 bis 300 Alm2 Dichte und benützen einen Schwefelsäureelektrolyten, oftmals mit geringen Zusätzen an Carbonsäuren. Eine hierzu bekannte Aluminiumlegierung enthält 4.5% Silizium und 0.5% Magnesium. Bei einer Stromdichte von 150 Alm2 entsteht nach 40 Min. eine Oxidschicht mit etwa 18 pm Dicke, welche eine mittelgraue Eigenfarbe aufweist. Die Lichtreflektivität, als Mass für den Grauton, beträgt 20%. Nach einer Oxidationsdauer von 60 Min. misst die Oxidschicht 27 pm und weist eine dunkelgraue Eigenfarbe mit 13% Lichtreflektivität auf. Die Reflektivität wurde hierzu mit einem LANGE UME 1-LFE 1-1-Messgerät ermittelt.With selected alloys and after observing special semi-finished product regulations, decorative gray tones can also be produced with standard anodizing processes. These inexpensive and widespread anodizing processes work with direct current from 80 to 300 Alm 2 density and use a sulfuric acid electrolyte, often with small additions of carboxylic acids. A known aluminum alloy contains 4.5% silicon and 0.5% magnesium. With a current density of 150 Alm 2 , an oxide layer with a thickness of approximately 18 pm is formed after 40 minutes, which has a medium-gray intrinsic color. The light reflectivity, as a measure of the gray tone, is 20%. After an oxidation time of 60 minutes, the oxide layer measures 27 pm and has a dark gray inherent color with 13% light reflectivity. For this purpose, the reflectivity was determined using a LANGE UME 1-LFE 1-1 measuring device.

Dieser Werkstoff neigt jedoch bei de Halbzeugfertigung - Walzen oder Strangpressen - zu übermässigem Werkzeugverschleiss. Zudem ist die Einhaltung enger Farbton- und Gleichmässigkeitstoleranzen recht schwierig.However, this material tends to excessive tool wear in semi-finished products - rolling or extrusion. It is also very difficult to maintain tight color and uniformity tolerances.

Aus FR-A-2 091 651 ist eine Aluminiumlegierung mit 0,05 bis 0,15% Kupfer, 0,5 bis 0,7% Eisen, 0,15 bis 0,3% Silizium, 0,3 bis 0,6% Mangan bekannt, mit welcher sich durch anodische Oxidation ein beiger Farbton erzeugen lässt.FR-A-2 091 651 is an aluminum alloy with 0.05 to 0.15% copper, 0.5 to 0.7% iron, 0.15 to 0.3% silicon, 0.3 to 0.6% Manganese known, with which a beige color can be produced by anodic oxidation.

FR-A-2 119 077 offenbart ein Verfahren, bei welchem Gegenstände aus einer Aluminiumlegierung mit 1 bis 3% Eisen zur Erzeugung eines gräulich silbrigen Farbtones anodisch oxidiert werden.FR-A-2 119 077 discloses a method in which objects made of an aluminum alloy are anodically oxidized with 1 to 3% iron to produce a greyish silvery hue.

Angesichts dieses Standes der Technik haben sich die Erfinder die Aufgabe gestellt, Aluminiumlegierungs-Erzeugnisse der eingangs genannten Art sowie ein Verfahren zu deren Herstellung zu schaffen, welches mit den üblichen Anodisierverfahren, ohne zusätzliche Färbestufe, eine gleichmässige, strukturfreie, lichtechte, graue Oberfläche von höchstens 50% Lichtreflektivität ermöglicht. Dabei soll mit einer konstanten Legierungszusammensetzung eine breite Palette von Grautönen herstellbar sein.In view of this state of the art, the inventors have set themselves the task of creating aluminum alloy products of the type mentioned at the outset and a process for their production which, with the usual anodizing processes, without an additional coloring step, provide a uniform, structure-free, lightfast, gray surface of at most 50% light reflectivity enabled. It should be possible to produce a wide range of shades of gray with a constant alloy composition.

Die Aufgabe wird erfindungsgemäss dadurch gelöst, dass die Legierung aus 1,20 bis 1,60% Eisen und 0,25 bis 0,55% Mangan mit einem Gewichtsverhältnis von Eisen zu Mangan zwischen 2,8 und 5, bis 0,20% Silizium, bis 0,30% Kupfer, bis 5% Magnesium, bis 0.10% Chrom, bis 2% Zink, bis 0.25% Zirkonium, bis 0.10% Titan, Rest Aluminium und gesamthaft bis 0.50% anderen Elementen besteht, wobei die Lichtreflektivität bei konstanter Legierungszusammensetzung bei Oxidschichten von 5 bis 30 um zwischen 8 und 45% einstellbar ist sowie bei Oxidschichten von 10 pm unter 30% liegt.The object is achieved according to the invention in that the alloy of 1.20 to 1.60% iron and 0.25 to 0.55% manganese with a weight ratio of iron to manganese between 2.8 and 5 to 0.20% silicon , up to 0.30% copper, up to 5% magnesium, up to 0.10% chromium, up to 2% zinc, up to 0.25% zirconium, up to 0.10% titanium, the rest aluminum and altogether up to 0.50% other elements, whereby the light reflectivity with constant alloy composition is adjustable between 8 and 45% for oxide layers of 5 to 30 µm and less than 30% for oxide layers of 10 pm.

Im Rahmen der Erfindung liegt auch ein Verfahren zum Herstellen dieser Aluminiumlegierungs-Erzeugnisse mit gleichmässig grauer, lichtechter Oberfläche und einer Lichtreflektivität von höchstens 50% durch anodische Oxidation in einem Elektrolyt ohne Zurätiliche Färbestuge, welcher sich dadurch auszeichnet, dass bei der Verarbeitung einer Legierung, bestehend aus 1.20 bis 1.60% Eisen und 0.25 bis 0.55% Mangan mit einem Gewichtsverhältnis von Eisen zu Mangan zwischen 2.8 und 5 sowie bis 0.20% Silizium, bis 0.30% Kupfer, bis 5% Magnesium, bis 0.10% Chrom, bis 2% Zink, bis 0.25% Zirkonium, bis 0.10% Titan, Rest Aluminium und gesamthaft bis 0.50% anderen Elementen vom Guss zum Erzeugnis alle Behandlungstemperaturen unter 560°C gehalten werden und die Verweildauer im Temperaturbereich zwischen 540 und 560°C höchstens 4 Stunden beträgt.Within the scope of the invention is also a method for producing these aluminum alloy products with a uniformly gray, light-fast surface and a light reflectivity of at most 50% by anodic oxidation in an electrolyte without additional dyeing tub, which is characterized in that when an alloy is processed, there is from 1.20 to 1.60% iron and 0.25 to 0.55% manganese with a weight ratio of iron to manganese between 2.8 and 5 and up to 0.20% silicon, up to 0.30% copper, up to 5% magnesium, up to 0.10% chromium, up to 2% zinc, up to 0.25% zirconium, up to 0.10% titanium, rest of aluminum and a total of up to 0.50% of other elements from the casting to the product, all treatment temperatures are kept below 560 ° C and the residence time in the temperature range between 540 and 560 ° C is a maximum of 4 hours.

Bevorzugt werden alle Behandlungstemperaturen, sowohl die im Zusammenhang mit Warmumformprozessen auftretenden, als auch die der Warmumformung vorgeschalteten, im für die Verarbeitung tiefstmöglichen Bereich gewählt und die Verweildauer bei Temperaturen oberhalb 300°C möglichst kurz gehalten.All treatment temperatures, both those which occur in connection with hot forming processes and those which precede the hot forming, are preferably selected in the lowest possible range for processing and the residence time at temperatures above 300 ° C. is kept as short as possible.

Als günstig hat es sich erwiesen, den Eisengehalt der eingesetzten Legierung zwischen 1.30 und 1.50%, das Gewichtsverhältnis von Eisen zu Mangan zwischen 3 und 4 und der Siliziumgehalt unter 0.08% zu halten; dies ermöglicht gleichmässig dunkle Grautöne auch bei verhältnismässig geringen Oxidschichten.It has proven advantageous to keep the iron content of the alloy used between 1.30 and 1.50%, the weight ratio of iron to manganese between 3 and 4 and the silicon content below 0.08%; this enables uniformly dark shades of gray even with relatively small oxide layers.

Eine vorteilhafte Ausführung besteht darin, die anodische Oxidation unter Verwendung von Gleichstrom in einem Schwefelsäureelektrolyt mit 10 bis 25 Gew.-% Schwefelsäure und bis 5% Carbonsäuren durchzuführen.An advantageous embodiment consists in carrying out the anodic oxidation using direct current in a sulfuric acid electrolyte with 10 to 25% by weight sulfuric acid and up to 5% carboxylic acids.

Vor der anodischen Oxidation kann die Oberfläche der Aluminium-Werkstücke noch durch Schleifen, Bürsten, Polieren, Aetzen, Glänzen und ähnlichem vorbehandelt werden.Before the anodic oxidation, the surface of the aluminum workpieces can be pretreated by grinding, brushing, polishing, etching, glossing and the like.

Dank dieses erfindungsgemässen Verfahrens ist es nunmehr möglich, jene Kaltwalzbleche und Strangpressprofile herzustellen, welche - ohne die Legierung variieren zu müssen - bei Standard-Anodisierverfahren im Oxiddickenbereich von 5 bis 30 pm eine Grautonpalette von 8 bis 45% Lichtreflektivität abdecken und bei welchen bei einer Oxidschichtdicke von 10 µm die Lichtreflektivität unter 30% liegt.Thanks to this method according to the invention, it is now possible to produce those cold-rolled sheets and extruded profiles which - without having to vary the alloy - cover a range of shades of gray of 8 to 45% light reflectivity in standard anodizing processes in the oxide thickness range from 5 to 30 pm, and those with an oxide layer thickness of 10 µm the light reflectivity is below 30%.

Weitere Vorteile, Merkmale und Einzelheiten der Erfindung ergeben sichaus der nachfolgenden Beschreibung bevorzugter Ausführungsbeispiele.Further advantages, features and details of the invention emerge from the following description of preferred exemplary embodiments.

Beispiel 1example 1

Aus einer Legierung mit 1.42% Eisen, 0.44% Mangan, 0.06% Silizium und Rest Aluminium mit 0.07% Verunreinigungen wurde ein rechteckiger Strang von 320 x 1080 mm2 Querschnitt gegossen. Der konventionell gegossene Barren wurde beidseits 10 mm überfräst. Bei Verwendung von Hot Top- oder Magnetfeldkokillen könnte davon abgesehen werden. Der Barren wurde sodann auf 520°C angewärmt und ohne Haltezeit einem Warmwalzgerüst zugeführt und zu einer platte von 8 mm Dicke gewalzt. Die mit einer Temperatur von 450°C austretende Platte wurde durch einen Wasserkasten geführt und auf eine Dicke von 1.0 mm kaltgewalzt. Nach einer Endglühung von 3 Stunden bei 320°C wies das Blech eine Zugfestigkeit Rm von 142 MPa, eine Streckgrenze Rp0.2 von 104 MPa und eine Dehnung A5 von 40% auf.A rectangular strand of 320 x 1080 mm 2 cross section was cast from an alloy with 1.42% iron, 0.44% manganese, 0.06% silicon and the rest aluminum with 0.07% impurities. The conventionally cast ingot was milled 10 mm on both sides. This could be dispensed with when using hot top or magnetic field molds. The ingot was then heated to 520 ° C and fed to a hot rolling stand without holding time and rolled into a sheet 8 mm thick. The plate emerging at a temperature of 450 ° C. was passed through a water box and cold-rolled to a thickness of 1.0 mm. After a final annealing of 3 hours at 320 ° C., the sheet had a tensile strength R m of 142 MPa, a yield strength R p0.2 of 104 MPa and an elongation A 5 of 40%.

Bleche von 980 x 980 mm2 wurden in einem Elektrolyten anodisch oxidiert. Das Bad enthielt 180 g Schwefelsäure und 10 g Oxalsäure pro Liter. Die Dichte des Gleichstroms betrug 150 A/m2. Die Oxidschicht eines während 20 Minuten anodisch oxidierten Bleches misst 10 pm. Das Blech zeigt über die gesamte Oberfläche eine gleichmässige, mittelgraue Farbe. Die mit dem LANGE UME 1-LFE 1-Messgerät ermittelte Lichtreflektivität beträgt 21%. Während 40 Minuten oxidierte Bleche weisen eine Oxidschicht von 20 µm Dicke auf. Die Lichtreflektivität der gleichmässig dunkelgrauen Oberfläche beträgt 12%.Sheets of 980 x 980 mm 2 were anodized in an electrolyte. The bath contained 180 g sulfuric acid and 10 g oxalic acid per liter. The density of the direct current was 150 A / m 2 . The oxide layer of a sheet anodized for 20 minutes measures 10 pm. The sheet shows a uniform, medium gray color over the entire surface. The light reflectivity determined with the LANGE UME 1-LFE 1 measuring device is 21%. Sheets oxidized for 40 minutes have an oxide layer 20 µm thick. The light reflectivity of the even dark gray surface is 12%.

Beispiel 2Example 2

Aus einer Legierung mit 1.45% Eisen, 0.43% Mangan, 0.15% Zirkonium, 0.05% Silizium und Rest Aluminium mit 0.04% Verunreinigungen wurde ein Rundbolzen von 200 mm Durchmesser gegossen. Der Bolzen wurde 2 mm tief überdreht und zum Strangpressen auf 490°C rasch angewärmt und ohne Haltezeit zu 3 Profilen mit je 140 mm2 Querschnittsfläche verpresst.A round bolt with a diameter of 200 mm was cast from an alloy with 1.45% iron, 0.43% manganese, 0.15% zirconium, 0.05% silicon and the rest aluminum with 0.04% impurities. The bolt was turned over 2 mm deep and quickly heated to 490 ° C for extrusion and pressed into 3 profiles with 140 mm 2 cross-sectional area each without holding time.

Die Pressschweissnähte aufweisenden Stränge traten mit einer Temperatur von 540°C aus der Matrize und wurden mit bewegter Luft abgekühlt. Zugversuche ergaben eine Zugfestigkeit Rm von 160 MPa und eine Streckgrenze Rp0.2 von 85 MPa.The strands having press weld seams emerged from the die at a temperature of 540 ° C. and were cooled with moving air. Tensile tests showed a tensile strength R m of 160 MPa and a yield strength R p0.2 of 85 MPa.

Strangabschnitte wurden in einem Bad mit 180 g Schwefelsäure und 10 g Oxalsäure pro Liter bei einem Gleichstrom mit einer Dichte von 200 A/ m2 anodisch oxidiert. Nach 13-minütiger Behandlung mass die Oxidschicht 9 um. Die Reflektivität beträgt 20%. Alle 3 Profile weisen eine gleichmässige, strukturfreie, mittelgraue Färbung auf. Farbunterschiede sind nicht zu erkennen.Strand sections were anodized in a bath with 180 g sulfuric acid and 10 g oxalic acid per liter at a direct current with a density of 200 A / m 2 . After 13 minutes of treatment, the oxide layer measured 9 µm. The reflectivity is 20%. All 3 profiles have a uniform, structure-free, medium gray color. There are no color differences.

Beispiel 3Example 3

Aus einer Legierung mit 1.48% Eisen, 0.40% Mangan, 1.2% Magnesium, 0.05% Silizium und Rest Aluminium mit 0.04% Verunreinigungen wurde ein Rundbolzen von 160 mm Durchmesser gegossen. Der Bolzen wurde 3 mm tief überdreht und zum Strangpressen auf 380°C rasch angewärmt und nach einer Haltezeit von einer Stunde zu einem Rechteck-Profil mit 4 x 30 mm2 Querschnitt mit einer Geschwindigkeit von 16m/ Minute verpresst. Der Strang trat mit einer Temperatur von 460°C aus der Matrize und wurde an der Luft abgekühlt. Die Zugfestigkeit Rm betrug 215 MPa, die Streckgrenze Rp0.2 106 MPa und die Bruchdehnung A5 21%. Nach einem Recken von 3% wurde ein Rm von 220 MPa, ein Rp0.2 von 173 MPa und ein A5 von 19% gemessen.A round bolt with a diameter of 160 mm was cast from an alloy with 1.48% iron, 0.40% manganese, 1.2% magnesium, 0.05% silicon and the rest aluminum with 0.04% impurities. The bolt was turned over 3 mm deep and quickly heated to 380 ° C for extrusion and pressed after a holding time of one hour to a rectangular profile with a cross section of 4 x 30 mm 2 at a speed of 16 m / minute. The strand emerged from the die at a temperature of 460 ° C. and was cooled in air. The tensile strength R m was 215 MPa, the yield strength R p0.2 106 MPa and the elongation at break A 5 21%. After 3% stretching, an R m of 220 MPa, an R p0.2 of 173 MPa and an A 5 of 19% were measured.

Strangabschnitte wurden in einem Bad mit 180 g Schwefelsäure und 10 g Oxalsäure pro Liter bei einem Gleichstrom mit einer Dichte von 150 A/m2 anodisch oxidiert. Nach 25-minütiger Behandlung mass die Oxidschicht 12 pm. Die Reflektivität beträgt 18%.Strand sections were anodized in a bath with 180 g sulfuric acid and 10 g oxalic acid per liter at a direct current with a density of 150 A / m 2 . After 25 minutes of treatment, the oxide layer measured 12 pm. The reflectivity is 18%.

Beispiel 4Example 4

Strangpressprofile aus dem Beispiel 2 wurden bei 25°C in einem wässrigen Bad mit 75 g Sulfosalicylsäure, 50 g Weinsäure und 5 g Schwefelsäure pro Liter bei einem Gleichstrom mit einer Dichte von 150 A/m2 anodisch oxidiert. Die Oxidschichtdicke betrug nach 25-minütiger Behandlung 9 µm. Die Reflektivität der dunkelgrauen Oberfläche beträgt 12%.Extruded profiles from Example 2 were anodized at 25 ° C. in an aqueous bath with 75 g sulfosalicylic acid, 50 g tartaric acid and 5 g sulfuric acid per liter at a direct current with a density of 150 A / m 2 . After 25 minutes of treatment, the oxide layer thickness was 9 μm. The reflectivity of the dark gray surface is 12%.

Beispiel 5Example 5

Strangpressprofile aus dem Beispiel 2 wurden bei 20°C in einem Bad mit 160 g Schwefelsäure und 20 g Glycerin pro Liter während 40 Minuten bei einer Gleichstromdichte von 150 A/m2 anodisch oxidiert. Die Dicke der resultierenden Oxidschicht beträgt 22 pm, die Reflektivität 11 %.Extruded profiles from Example 2 were anodized at 20 ° C. in a bath with 160 g sulfuric acid and 20 g glycerol per liter for 40 minutes at a direct current density of 150 A / m 2 . The thickness of the resulting oxide layer is 22 pm, the reflectivity 11%.

Beispiel 6Example 6

Strangpressprofile aus dem Beispiel 2 wurden bei 20°C in einem Bad mit 200 g Schwefelsäure pro Liter während 20 Minuten anodisch oxidiert. Die Stromdichte alternierte mit einer Frequenz von 25 Hz zwischen den beiden Niveaux 150 und 200 Alm2 mit jeweils 20 ms Verweilzeit. Die resultierende Oxidschicht misst 12 pm und weist eine Reflektivität von 16% auf.Extruded profiles from Example 2 were anodized at 20 ° C. in a bath with 200 g sulfuric acid per liter for 20 minutes. The current density alternated with a frequency of 25 Hz between the two Niveaux 150 and 200 Alm 2 , each with a dwell time of 20 ms. The resulting oxide layer measures 12 pm and has a reflectivity of 16%.

Claims (4)

1. Aluminium alloy products in the form of extruded sections or cold-rolled sheet with a uniformly grey, light-fast surface and a light reflectivity of at most 50% obtained by anodic oxidation in an electrolyte without an additional colouring stage, characterized in that the alloy consists of 1.20 to 1.60% of ircn and 0.25 to 0.55% of manganese at an iron/manganese weight ratio of between 2.8 and 5, up to 0.20% of silicon, up to 0.30% of copper, up to 5% of magnesium, up to 0.10% of chromium, up to 2% of zinc, up to 0.25% of zirconium and up to 0.10% of titanium, the remainder being aluminium with up to a total of 0.50% of other elements, the light reflectivity at constant alloy composition being adjustable between 8 and 45% in the case of oxide layers from 5 to 30 pm, and being below 30% in the case of oxide layers of 10 pm.
2. Process for the manufacture of the aluminium alloy products according to Claim 1, with a uniformly grey, light-fast surface and a light reflectivity of at most 50% by anodic oxidation in an electrolyte without an additional colouring stage, characterized in that, when processing an alloy consisting of 1.20 to 1.60% of iron and 0.25 to 0.55-% of manganese at an iron/ manganese weight ratio of between 2.8 and 5, up to 0.20% of silicon, up to 0.30% of copper, up to 5% of magnesium, up to 0.10% of chromium, up to 2% of zinc, up to 0.25% of zirconium and up to 0.10% of titanium, the remainder being aluminiumwith up to a total of 0.50% of other elements, all the treatment temperatures from casting to the product are kept below 560°C, the residence time in the temperature range between 540 and 560°C being at most 4 hours.
3. Process according to Claim 2, characterized in that the iron content of the alloy employed is between 1.30 and 1.50%, the iron/manganese weight ratio is between 3 and 4 and the silicon content is below 0.08%.
4. Process according to Claim 2 or 3, characterized in that the anodic oxidation is carried out using direct current in a sulphuric acid electrolyte with 10 to 25% by weight of sulphuric acid and up to 5% of carboxylic acid.
EP87810276A 1986-05-14 1987-04-30 Aluminium alloy products with uniform grey, light-fast surfaces, and process for their production Expired - Lifetime EP0246186B1 (en)

Priority Applications (2)

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DE19863616725 DE3616725A1 (en) 1986-05-14 1986-05-17 Manufacture of aluminium alloy products having a uniformly grey, light-fast surface
AT87810276T ATE60373T1 (en) 1986-05-14 1987-04-30 ALUMINUM ALLOY PRODUCTS WITH UNIFORMLY GRAY, LIGHT-LIGHT SURFACE AND PROCESS FOR THEIR MANUFACTURE.

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CH195686 1986-05-14
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US4935203A (en) * 1987-10-13 1990-06-19 Intevep, S.A. Corrosion resistant aluminum alloy
US4915798A (en) * 1987-10-13 1990-04-10 Intevep, S.A. Corrosion resistant aluminum product with uniformly grey, light-fast surface and process for its manufacture
US5380379A (en) * 1993-08-18 1995-01-10 Alcoa Aluminio Do Nordeste S.A. Aluminum foil product and manufacturing method
US5820015A (en) * 1996-04-02 1998-10-13 Kaiser Aluminum & Chemical Corporation Process for improving the fillet-forming capability of brazeable aluminum articles
ITTO20010149A1 (en) * 2001-02-20 2002-08-20 Finmeccanica S P A Alenia Aero LOW ECOLOGICAL ANODIZATION PROCEDURE OF A PIECE OF ALUMINUM OR ALUMINUM ALLOYS.
US7018521B2 (en) * 2001-09-27 2006-03-28 General Motors Corporation Method of producing bright anodized finishes for high magnesium, aluminum alloys
US6866945B2 (en) * 2003-01-06 2005-03-15 General Motors Corporation Magnesium containing aluminum alloys and anodizing process
CN108149085B (en) * 2017-12-14 2020-08-28 中铝材料应用研究院有限公司 Aluminum material without annealing treatment and with excellent surface quality and preparation method thereof
CN114107752B (en) * 2021-12-15 2022-06-21 中铝河南洛阳铝加工有限公司 high-Cr aluminum alloy plate strip for anodic oxidation and preparation method thereof

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DE2124107A1 (en) * 1970-05-14 1972-01-27 Aluminum Co Of America Manufacture of colored anodized parts
JPS4916341B1 (en) * 1970-12-26 1974-04-22
DE3425860A1 (en) * 1984-07-13 1986-01-16 Hoechst Ag, 6230 Frankfurt CARRIER MATERIAL FOR PRINTING PLATES FROM AN ALUMINUM ALLOY AND PRINTING PLATE FROM THIS MATERIAL

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