Method of making high strength aluminum alloy forgings and product produced thereby

Claim 2

In the method of producing a high strength aluminum forging, the steps comprising:

Claim 3

forging said body at a deformation ratio of at least 8:1 while maintaining in the metal a temperature of at least 750*F,

Claim 4

subjecting the body to at least one sustained exposure to a temperature of at least 900*F.

Claim 5

homogenizing said ingot by heating to a temperature of at least 860*F,

Claim 6

working said body at a deformation ratio of at least 8:1 while maintaining in the metal a temperature of at least 750*F, said working including at least some forging,

Claim 7

working said ingot at a deformation ratio of at least 8 to 1 while maintaining in the metal a temperature of at least 790*F to provide forging stock,

Claim 8

subjecting said body to at least one sustained exposure to a temperature of at least 900*F.

Claim 9

In the method of producing a high strength aluminum forging, the steps comprising:

Claim 10

subjecting said body to at least one sustained exposure to a temperature of at least 900*F.

Claim 11

working said ingot at a deformation ratio of at least 8:1 while maintaining in the metal a temperature of at least 750*F to provide forging stock,

Claim 12

soaking said forging stock at a temperature of 900* to 970*F for a period of at least 2 hours,

Claim 13

In the method according to claim 3 the additional steps of solution heat treating the said forged product by heating it to a temperature of at least 900*F for a time sufficient to place substantially all the soluble alloy constituents in solid solution and quenching the forged product.

Claim 14

soaking said forging stock at a temperature of 925* to 970*F for a minimum time period of 2 hours,

Claim 15

forging the forging stock to provide a forging while maintaining throughout the forging operation a metal temperature of at least 790*F,

Claim 16

In the method according to claim 4 the additional step of artificially aging said forged product.

Claim 17

forging the forging stock to provide a forged product while maintaining throughout the forging operation a metal temperature of at least 750*F.

Claim 18

In the method according to claim 1 wherein major portions of said working in said step (2) are performed at metal temperatures of at least 790*F.

Claim 19

solution heat treating said forging by heating it to a temperature within the range of 925* to 980*F for a time sufficient to place substantially all the soluble alloy constituents in solid solutiOn,

Claim 20

quenching said forging,

Claim 21

In the method according to claim 2 wherein in said step (2) a major portion of said forging is performed at a metal temperature of at least 790*F.

Claim 22

In the method according to claim 3 wherein major portions of said working in said step (3) and said forging in said step (5) are performed at metal temperatures of at least 790*F.

Claim 23

artificially aging said quenched forging, said forging being characterized by very high strength.

Claim 24

In the method according to claim 1 wherein said exposure in said step (3) is at a temperature of at least 925*F.

Claim 25

In the method according to claim 2 wherein said exposure in said step (3) is at a temperature of at least 925*F.

Claim 26

In the method according to claim 9 wherein said body contains 5.6 to 7% zinc, 2.4 to 2.75% magnesium, 1.4 to 1.9% copper and 0.18 to 0.35% chromium.

Claim 27

In the method according to claim 10 wherein said body contains 5.6 to 7% zinc, 2.4 to 2.75% magnesium, 1.4 to 1.9% copper and 0.18 to 0.35% chromium.

Claim 29

The method according to claim 3 wherein said forging is artificially aged by heating to a temperature of 215* to 250*F and holding at said temperature for a minimum time of 6 hours and thereafter heating to a temperature within the range of 340* to 360*F and holding at said temperature for a duration which imparts the effects of a 7 1/2 to 9 1/2 hour exposure at a temperature of exactly 350*F so as to impart to said forging an electrical conductivity of 38 to 42% IACS, said forging being characterized by high resistance to stress corrosion cracking and by a minimum strength level of 76,000 psi tensile and 66,000 psi yield strength and a minimum elongation of 7% in the longitudinal direction.

Claim 30

The method according to claim 3 wherein said forging is artificially aged at a temperature within the range of 215* to 250*F for a minimum period of 50 hours, said forging being characterized by a strength level of 86,000 psi tensile and 76, 000 psi yield strength and a minimum elongation of 7% in the longitudinal direction.

Claim 31

The method according to claim 3 wherein extrusion is employed in producing the forging stock in said step (3).

Claim 32

The method according to claim 3 wherein extrusion is employed to produce the forging stock in said step (3) and the first portion of the extruded forging stock is discarded, the discarded portion amounting to at least 20% of the total extruded length.

Claim 33

The method according to claim 3 wherein said forging stock, prior to forging, is soaked at a temperature of 925* to 970*F for a minimum time of 8 hours.

Claim 34

The method according to claim 3 wherein said ingot contains 5.6 to 6% zinc.

Claim 35

The method according to claim 1 wherein said body is homogenized at a temperature of at least 860*F prior to said working of said step (2).

Claim 36

The method according to claim 2 wherein said body is homogenized at a temperature of at least 860*F prior to said forging of said step (2).

Claim 37

The method according to claim 1 wherein said forging is artificially aged by heating to a temperature of 215* to 250*F and holding at said temperature for a minimum time of 6 hours and thereafter heating to a temperature within the range of 340* to 360*F and holding at said temperature for a duration which imparts the effects of a 7 1/2 to 9 1/2 hour exposure at a temperature of exactly 350*F so as to impart to said forging an electrical conductivity of 38 to 42% IACS, said forging being characterized by high resistance to stress corrosion cracking and by a minimum strength level of 76,000 psi tensile and 66,000 psi yield strength and a minimum elongation of 7% in the longitudinal direction.

Claim 38

The method according to claim 1 wherein said forging is artificially aged at a temperature within the range of 215* to 250*F for a minimum period of 50 hours, said forging being characterized by a strength level of 86,000 psi tensile and 76, 000 psi yield strength and a minimum elongation of 7% in the longitudinal direction.

Claim 39

A method according to claim 1 wherein extrusion to a deformation ratio of at least 8:1 is employed in said step (2) to produce stock which is forged.

Claim 40

The method according to claim 1 wherein, in said step (2), said body is first worked to a deformation ratio of at least 8:1, and then soaked at a temperature of 925* to 970*F for a minimum time of 2 hours and then forged.

Claim 41

The method according to claim 1 wherein said ingot Contains 5.6 to 6% zinc.

Claim 42

In a method of producing an improved high strength forging of an aluminum alloy of the zinc-magnesium-copper type wherein a body of the alloy is forged at a deformation ratio of at least 8: 1 while maintaining a metal temperature of at least 750*F and is subjected to at least one sustained exposure to a temperature of at least 900*F, the step of providing said body in an alloy having a composition consisting essentially of 4.8 to 8.5% zinc, 1.7 to 3.5% magnesium, 0.8 to 2.5% copper, at least one grain controlling element selected from the group consisting of 0.1 to 0.75% manganese, 0.05 to 0.4% chromium, 0.05 to 0.3% zirconium, 0.05 to 0.3% vanadium, 0.05 to 0.3% molybdenum, the balance being substantially aluminum, said alloy being cast while maintaining in the molten metal phase within the casting mold a maximum gas content of 0.15 ml/100 g of melt to achieve substantial freedom from porosity, the metal solidification being controlled such that the chill rate throughout the solidification temperature zone is a minimum of 2*F per second.

Claim 43

In a method of producing an improved high strength forging of an aluminum alloy of the zinc-magnesium-copper type wherein a body of the alloy is worked at a deformation ratio of at least 8: 1, said working including at least some forging, while maintaining a metal temperature of at least 750*F, and is subjected to at least one sustained exposure to a temperature of at least 900*F, the step of providing said body in an alloy having a composition consisting essentially of 4.8 to 8.5% zinc, 1.7 to 3.5% magnesium, 0.8 to 2.5% copper, at least one grain controlling element selected from the group consisting of 0.1 to 0.75% manganese, 0.05 to 0.4% chromium, 0.05 to 0.3% zirconium, 0.05 to 0.3% vanadium, 0.05 to 0.3% molybdenum, the balance being substantially aluminum, said alloy being cast while maintaining in the molten metal phase within the casting mold a maximum gas content of 0.15 ml/100 g of melt to achieve substantial freedom from porosity, the metal solidification being controlled such that the chill rate throughout the solidification temperature zone is a minimum of 2*F per second.

Claim 44

In the method of producing an improved high strength forging of an aluminum alloy of the zinc-magnesium-copper type wherein a body of said alloy is provided having a composition consisting essentially of 4.8 to 8.5% zinc, 1.7 to 3.5% magnesium, 0.8 to 2.5% copper, at least one grain controlling element selected from the group consisting of 0.1 to 0.75% manganese, 0.05 to 0.4% chromium, 0.05 to 0.3% zirconium, 0.05 to 0.3% vanadium, 0.05 to 0.3% molybdenum, the balance being substantially aluminum, said alloy being cast while maintaining in the molten metal phase within the casting mold a maximum gas content of 0.15 ml/100 g of melt to achieve substantial freedom from porosity, the metal solidification being controlled such that the chill rate throughout the solidification temperature zone is a minimum of 2*F per second, and the body is worked at a deformation ratio of at least 8:1 while maintaining a metal temperature of at least 750*F, the step of subjecting said body to at least one sustained exposure to a temperature of at least 900*F.

Claim 45

In a method of producing a high strength aluminum alloy forging, the steps comprising:

Claim 46

In the method according to claim 30 wherein said sustained temperature exposure in said step (2) follows said working in said step (1).

Claim 47

In the method according to claim 30 wherein said working imparts a deformation ratio of at least 8:1.

Claim 48

The method according to claim 30 wherein said thermal exposure is at a temperature of at least 925*F.

Claim 49

The method according to claim 1 wherein said body contains not more than 0.12% silicon and not more than 0.15% iron.

Claim 50

The method according to claim 2 wherein said body contains not more than 0.12% silicon and not more than 0.15% iron.

Claim 51

The method according to claim 3 wherein said body contains not more than 0.12% silicon and not more than 0.15% iron.

Claim 52

The method according to claim 27 wherein said body contains not more than 0.12% silicon and not more than 0.15% iron.

Claim 53

The method according to claim 28 wherein said body contains not more than 0.12% silicon and not more than 0.15% iron.

Claim 54

An improved forging produced according to the method of claim 30.

Claim 55

An improved forging produced by the method of claim 1.