Method for producing a high damage tolerant aluminium alloy

a technology of high damage tolerance and alloy, which is applied in the field of high damage tolerance aluminium alloy production, can solve the problems that aa2000 and aa6000 series alloys are generally unsuitable for the design of commercial aircraft, and achieve the effects of improving fatigue crack growth resistance, improving toughness, and maintaining strength levels

Inactive Publication Date: 2006-02-16
ALERIS ALUMINUM KOBLENZ GMBH
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  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

[0012] It is an object of the present invention to provide a method for producing an aluminium alloy product having an improved toughness and an improved fatigue crack growth resistance thereby maintaining the strength levels of conventional AA2000-, AA6000-, AA5000- or AA7000-series alloys.
[0013] More specifically, it is an object of the present invention to provide an improved method for producing high damage tolerant (“HDT”) aluminium alloys with balanced properties with regard to fatigue crack growth resistance, toughness, corrosion resistance and strength. The HDT-properties should preferably be better than those of conventional manufactured AA6013-T6, 6056-T6 alloys and preferably better than AA2024-T3 or AA2524-T3 alloys.
[0017] In one aspect, the present invention provides a method for producing a high damage tolerant aluminium alloy rolled product a high toughness and an improved fatigue crack growth resistance, including the steps of

Problems solved by technology

Several other AA2000 and AA6000 series alloys are generally unsuitable for the design of commercial aircraft which require different sets of properties for different types of structures.

Method used

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  • Method for producing a high damage tolerant aluminium alloy
  • Method for producing a high damage tolerant aluminium alloy

Examples

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example 1

[0052] In a first preferred embodiment of the present invention, two conventional alloys (AA6013 and AA6056) were cast and processed to a sheet product. Here, two processing variants were used:

[0053] Route 1. A normal processing route by lab-casting ingots of conventional AA6013 and AA6056-alloy compositions was used. Blocks of 80×80×100 mm were sawn, homogenised, preheated and hot rolled to 4.5 mm sheet. After hot rolling the hot rolled products were conventionally cooled to ambient temperature by allowing the sheet to cool to ambient air to room temperature, fed to the cold rolling station, cold rolled to 2 mm and heat treated for 20 min at 550° C., thereafter quenched and aged to a T6-temper for 4 hours at 190° C.

[0054] Route 2. Ingots of conventional AA6013 and AA6056-alloy compositions were lab-cast and sawn to a size of 80×80×100 mm. These blocks were homogenised, pre-heated and hot rolled to 4.5 mm. A simulation of the hot coiling in an industrial scale was incorporated by ...

example 2

[0078]FIG. 1 shows a typical continuous cooling down curve for an aluminium AA7050 alloy when cooled down from a hot-mill exit temperature of 440° C. to a temperature below 150° C., whereby the metal sheet has a gauge of 4.5 mm and being immediately coiled when leaving the hot-mill in accordance with an embodiment of the method of this invention. The width of the coil was 1.4 meter. The temperatures of the coil as function of time is also given in Table 7 for the hottest spot of a coil (being the centre, and indicated as HotSpt in FIG. 1) and the coldest spot (being the edge of a coil, and indicated as ColdSpt in FIG. 1)). Table 7 provides also the temperatures in case a coil having a width of 2.8 meter.

[0079] For the shown cooling curve in FIG. 1 the α is about −0.084 hrs−1.

[0080] In case a sheet with a gauge of about 4.0 to 4.5 mm was allowed to cool down from the hot-mill exit temperature to below 150° C. using conventional cooling practice, viz. leaving the plate to cool in no...

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Abstract

The present invention relates to a method of producing a high damage tolerant aluminium alloy rolled product a high toughness and an improved fatigue crack growth resistance, including the steps of: a.) casting an ingot having a composition selected from the group comprising AA2000, AA5000, AA6000, and AA7000-series alloys; b.) homogenising and / or pre-heating the ingot after casting; c.) hot rolling the ingot into a hot rolled product and optionally cold rolling the hot rolled product into a cold rolled product, wherein the hot rolled product leaves the hot rolling mill at an hot-mill exit temperature (TExit) and cooling the hot rolled product from the TExit to 150° C. or lower with a controlled cooling cycle with a cooling rate falling within the range defined by: T(t)=50−(50−TExit)eαt and wherein T(t) is the temperature (° C.) as function in time (hrs), t is the time (hours) and α is in the range of −0.09±0.05 (hrs−1).

Description

CROSS REFERENCE TO RELATED APPLICATIONS [0001] This claims priority under 35 USC 119 from European application no. 03078410.2 filed on 29 Oct. 2003 and U.S. provisional application 60 / 515,699 filed on 31 Oct. 2003, both incorporated herein by reference in their entirety.FIELD OF THE INVENTION [0002] The present invention discloses a method for producing a high damage tolerant aluminium rolled alloy having a good toughness and an improved fatigue crack growth resistance while maintaining good strength levels and to an aluminium alloy sheet or plate product having such a high toughness and an improved fatigue crack growth resistance. Furthermore, the invention relates to the use of an alloy product obtained by the method of this invention. BACKGROUND OF THE INVENTION [0003] It is known in the art to use heat treatable aluminium alloys in a number of applications involving relatively high strength such as aircraft fuselages, vehicular members and other applications. Aluminium alloys AA...

Claims

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Application Information

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Patent Type & Authority Applications(United States)
IPC IPC(8): C22F1/04
CPCC22F1/04
Inventor BENEDICTUS, RINZEHEINZ, ALFRED LUDWIGKEIDEL, CHRISTIAN JOACHIMHASZLER, ALFRED JOHANN PETERWEBER, GUIDO
Owner ALERIS ALUMINUM KOBLENZ GMBH
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