High strength aluminum alloys and process for making the same

a technology of aluminum alloy and high strength, applied in the field of high strength aluminum alloy, can solve problems such as reducing toughness, and achieve the effects of reducing the amount of low melting point eutectic phases, and maximizing alloying effectiveness

Inactive Publication Date: 2006-09-28
BROOKS CHARLES E +4
View PDF1 Cites 12 Cited by
  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

[0009] To maximize alloying effectiveness during formation of the alloys, a homogenization process is preferably employed after alloy ingot casting in which a slow rate of temperature increase is employed as the alloy is heated as near as possible to its melting temperature. In particular, for the last 20-30° F. below the melting temperature, the rate of increase is limited to 20° F./hr. or less to minimize the amount of low melting point eutectic phases and thereby further enhance fracture toughness of the alloy. Once the ingot is formed into finished shape using extrusion and rolling steps, for example, the product is preferably solution heat treated at 870 to 900 degrees F. and then artificially aged. The aging process can be carried out by exposing the product to a one, two or three step heat treatment process. In the first step, the product is exposed to a temperature range of 175-310 degrees F. for ...

Problems solved by technology

Additionally, it has been found that toughness decreases a...

Method used

the structure of the environmentally friendly knitted fabric provided by the present invention; figure 2 Flow chart of the yarn wrapping machine for environmentally friendly knitted fabrics and storage devices; image 3 Is the parameter map of the yarn covering machine
View more

Image

Smart Image Click on the blue labels to locate them in the text.
Viewing Examples
Smart Image
  • High strength aluminum alloys and process for making the same
  • High strength aluminum alloys and process for making the same
  • High strength aluminum alloys and process for making the same

Examples

Experimental program
Comparison scheme
Effect test

example 1

[0019] A heretofore unexplored region of the Al—Zn—Mg—Cu alloy system consists of compositions comprising about 9% to 10% zinc, 2.2% to 2.8% copper, and 1.6% to 2.0% magnesium. The alloy compositions listed in Table 1 were cast as 9-in. diameter billets: note that all these alloys contain about 0.05% scandium, an element which in combination with zirconium is effective in preventing recrystallization.

TABLE 1Alloy compositionsPercent by WeightAlloySiFeCuMgZnZrSc1790.040.072.471.838.870.140.061800.040.092.711.898.950.130.061890.040.082.141.898.600.120.051900.030.092.311.869.210.130.051910.030.112.351.819.630.130.051920.040.102.331.8710.130.120.052000.040.092.581.648.840.120.052020.040.122.461.668.870.130.052030.040.102.691.788.940.130.052040.030.102.881.588.780.120.052090.040.082.641.498.780.140.052130.030.072.421.639.650.130.052140.030.092.561.449.500.140.052150.040.092.571.739.820.120.052160.030.102.811.609.650.130.05

[0020] The billets were homogenized at 880 F. (F means degrees F...

example 2

[0023] To compare the invention alloy with other commercial high-zinc alloys such as AA7036, AA7056 and AA7449, which have higher Mg / Cu ratios in the range 1.0 to 1.4, the following alloys were prepared as described in Example 1.

TABLE 3Compositions of Comparative AlloysPercent by WeightAlloy No.SiFeCuMgZnZrSc360.030.061.912.179.020.150.05390.040.051.282.749.020.130.06430.030.031.442.629.040.130.05470.040.061.592.348.950.140.06

[0024] The yield strengths and toughness values for these alloys are listed in the following table.

TABLE 4Mechanical Properties of Comparative AlloysMg / CuYieldKpmaxAlloyRatio%(Mg + Cu)Strength (ksi)(ksi rtin.)361.144.0894.924.5471.473.9393.922.7431.773.9993.921.3392.144.0292.720.2

[0025]FIG. 4 compares the toughness levels of these alloys on the basis of Mg / Cu ratio with the invention alloys, using those compositions that have similar strength levels (93-95 ksi) and total Mg+Cu contents (4.0-4.2%).

example 3

[0026] As noted earlier it is important that undissolved second phases do not remain after processing so that fracture toughness can be maximized. This is especially important in alloys that are rich in alloy content, and lie near an equilibrium solvus phase boundary. To illustrate how homogenizing practice can affect the amount of such undissolved phase(s), samples of as-cast AA7068 alloy billet were heated from 850 F. at various rates in a differential scanning calorimeter (DSC), and the energy associated with eutectic melting, which started at about 885 F. was measured. This energy measurement is directly proportional to the amount of undissolved second phase remaining at the incipient melting point, and the relationship between these factors has been determined by quantitative microscopy. FIG. 5 shows how heating rate affects the amount of this phase as determined from the DSC data.

[0027] Note that a slow heating rate of about 10 F. / hr reduces the amount of second phase to a le...

the structure of the environmentally friendly knitted fabric provided by the present invention; figure 2 Flow chart of the yarn wrapping machine for environmentally friendly knitted fabrics and storage devices; image 3 Is the parameter map of the yarn covering machine
Login to view more

PUM

PropertyMeasurementUnit
Temperatureaaaaaaaaaa
Temperatureaaaaaaaaaa
Temperatureaaaaaaaaaa
Login to view more

Abstract

High strength aluminum alloys based on the Al—Zn—Mg—Cu alloy system preferably include high levels of zinc and copper, but modest levels of magnesium, to provide increased tensile strength without sacrificing toughness. Preferred ranges of the elements include by weight, 8.5-10.5% Zn, 1.4-1.85 % Mg, 2.25-3.0% Cu and at least one element from the group Zr, V, or Hf not exceeding about 0.5%, the balance substantially aluminum and incidental impurities. In addition, small amounts of scandium (0.05-0.30%) are also preferably employed to prevent recrystalization. During formation of the alloys, homogenization, solution heat treating and artificial aging processes are preferably employed.

Description

CROSS REFERENCE TO RELATED APPLICATIONS [0001] This application contains subject matter that is related to the subject matter set forth in U.S. application Ser. No. 10 / 829,391, which was filed on Apr. 22, 2004.BACKGROUND OF THE INVENTION [0002] 1. Field of the Invention [0003] The present invention relates, in general, to a high strength aluminum alloy based on the Al—Zn—Mg—Cu alloy system and a process for forming the same. Although not limited thereto, the alloys are particularly suited for use in sporting goods and aerospace applications. [0004] 2. Description of the Background Art [0005] The highest strength aluminum alloys known at this time are based on the aluminum-zinc-magnesium-copper system. Commercial high-strength alloys currently being produced include AA7055 (nominally 8% Zn-2% Mg-2.2% Cu-0.10% Zr), AA7068 (nominally 7.8% Zn-2.5% Mg-2.0% Cu-0.10% Zr) and a Kaiser Aluminum alloy designated K749 (nominally 8% Zn-2.2% Mg-1.8% Cu-0.14% Zr). From the published phase relatio...

Claims

the structure of the environmentally friendly knitted fabric provided by the present invention; figure 2 Flow chart of the yarn wrapping machine for environmentally friendly knitted fabrics and storage devices; image 3 Is the parameter map of the yarn covering machine
Login to view more

Application Information

Patent Timeline
no application Login to view more
IPC IPC(8): C22C21/10
CPCC22C21/10C22F1/053
Inventor BROOKS, CHARLES E.DORWARD, RALPH C.PARKINSON, RAY D.MATUSKA, ROB A.SHAARBAF, MORY
Owner BROOKS CHARLES E
Who we serve
  • R&D Engineer
  • R&D Manager
  • IP Professional
Why Eureka
  • Industry Leading Data Capabilities
  • Powerful AI technology
  • Patent DNA Extraction
Social media
Try Eureka
PatSnap group products

Browse by: Latest US Patents, China's latest patents, Technical Efficacy Thesaurus, Application Domain, Technology Topic.

© 2024 PatSnap. All rights reserved.Legal|Privacy policy|Modern Slavery Act Transparency Statement|Sitemap