High-strength aluminum alloy and manufacturing method thereof

Patent metadata

Field	Value
Publication number	US-2016333453-A1
Application number	US-201415110443-A
Country	US
Kind code	A1
Filing date	Sep 26, 2014
Priority date	Jan 29, 2014
Publication date	Nov 17, 2016
Grant date	—

Abstract

An aluminum alloy contains, in mass percent, Zn: 2.5% or more and less than 5.0%, Mg: 2.2% or more and 3.0% or less, and Ti: 0.001% or more and 0.05% or less, Cu: 0.10% or less, Zr: 0.10% or less, Cr: 0.03% or less, Fe: 0.30% or less, Si: 0.30% or less, and Mn: 0.03% or less, the remainder being composed of Al and unavoidable impurities. In addition, the tensile strength is 380 MPa or more; the electrical conductivity is 38.0% IACS or more; and the metallographic structure is composed of a recrystallized structure.

First claim

1 .- 5 . (canceled)

6 . An aluminum alloy, comprising in mass percent:
Zn: 2.5% or more and less than 5.0%, Mg: 2.2% or more and 3.0% or less, Ti: 0.001% or more and 0.05% or less, Cu: 0.10% or less, Zr: 0.10% or less, Cr: 0.03% or less, Fe: 0.30% or less, Si: 0.30% or less, and Mn: 0.03% or less, the remainder being composed of Al and unavoidable impurities, wherein the aluminum alloy has:
a tensile strength of 380 MPa or more;
an electrical conductivity of 38.0% IACS or more; and
a metallographic structure composed of a recrystallized structure.

7 . The aluminum alloy according to claim 6 , wherein:
the recrystallized structure includes crystal grains having an average grain diameter of 500 μm or less, and a crystal grain length in a direction parallel to a hot working direction is 0.5 to 4 times as long as a crystal grain length in a direction perpendicular to the hot working direction.

8 . The aluminum alloy according to claim 7 , wherein Zn is 2.5% or more and 4.8% or less.

9 . The aluminum alloy according to claim 8 , wherein the aluminum alloy has an anodized surface that has a gloss value of 600 or more.

10 . The aluminum alloy according to claim 9 , wherein the recrystallized structure is a granular recrystallized structure.

11 . The aluminum alloy according to claim 6 , wherein Zn is 2.5% or more and 4.8% or less.

12 . The aluminum alloy according to claim 6 , wherein the aluminum alloy has an anodized surface that has a gloss value of 600 or more.

13 . The aluminum alloy according to claim 6 , wherein the recrystallized structure is a granular recrystallized structure.

14 . A process for producing a wrought aluminum alloy material, which comprises:
preparing an ingot having a chemical composition comprising, in mass percent, Zn: 2.5% or more and less than 5.0%, Mg: 2.2% or more and 3.0% or less, Ti: 0.001% or more and 0.05% or less, Cu: 0.10% or less, Zr: 0.10% or less, Cr: 0.03% or less, Fe: 0.30% or less, Si: 0.30% or less, and Mn: 0.03% or less, the remainder being composed of Al and unavoidable impurities, performing a homogenization treatment that heats the ingot at a temperature of 540° C. or higher and 580° C. or lower for 1 hour to 24 hours; subsequently, forming a wrought material by performing hot working on the ingot in a state where the temperature of the ingot at the beginning of the working is 440° C. to 560° C.; while the wrought material is still at 400° C. or higher, starting to cool it and subsequently performing a quenching treatment such that, while the wrought material is cooling down from 400° C. to 150° C., the average cooling rate is 1° C./s or more and 300° C./s or less; cooling the temperature of the wrought material to room temperature by said quenching treatment or by an additional cooling treatment; and thereafter, performing an artificial aging treatment on the wrought material.

15 . The process according to claim 14 , wherein the artificial aging treatment comprises performing a first artificial aging treatment at a temperature of 80° C. to 120° C. for 1 hour to 5 hours, and continuously after the first artificial aging treatment, performing a second artificial aging treatment that heats the wrought material at a temperature of 145° C. to 200° C. for 2 hours to 15 hours.

16 . The process according to claim 14 , wherein the artificial aging treatment comprises heating the wrought material at a temperature of 145° C. to 180° C. for 1 hour to 24 hours.

17 . The process according to claim 14 , wherein the hot working involves extrusion or rolling.

18 . The process according to claim 14 , wherein during the quenching step, the average cooling rate is 3° C./s or more and 300° C./s or less

19 . The process according to claim 14 , wherein the second artificial aging treatment is performed at a temperature of 170° C. to 200° C.

20 . The process according to claim 14 , further comprising anodizing the wrought material after the artificial aging treatment.

21 . The process according to claim 14 , wherein:
the homogenization treatment is performed at 555° C. for 5 hours, the hot working comprises hot extruding the ingot while the temperature of the ingot is at 520° C., the quenching treatment is initiated while the temperature of the wrought material is at 510° C. and the average cooling rate of the quenching treatment is 60° C./sec, thereafter the wrought material is subjected to room temperature aging for 48 hours, the first artificial aging treatment involves heating the wrought material at 100° C. for 3 hours, and the second artificial aging treatment involves heating the wrought material at 150° C. for 8 hours.

22 . The process according to claim 21 , further comprising anodizing the wrought material after the second artificial aging treatment.

23 . A process for producing the aluminum alloy of claim 6 , comprising:
homogenizing an ingot having the elemental composition recited in claim 6 at a temperature of 540° C. or higher and 580° C. for at least 1 hour; hot working on the homogenized ingot while the temperature of the ingot at the beginning of the hot working is 440° C. to 560° C., thereby forming a wrought material, while the wrought material is still at 400° C. or higher, starting to cool it and subsequently performing a quenching treatment such that, while the wrought material is cooling down from 400° C. to 150° C., the average cooling rate is 1° C./s or more and 300° C./s or less; cooling the temperature of the wrought material to room temperature by said quenching treatment or by an additional cooling treatment; and thereafter, performing an artificial aging treatment on the wrought material.

24 . The process according to claim 23 , wherein the artificial aging treatment comprises performing a first artificial aging treatment at a temperature of 80° C. to 120° C. for 1 hour to 5 hours, and continuously after the first artificial aging treatment, performing a second artificial aging treatment that heats the wrought material at a temperature of 145° C. to 200° C. for 2 hours to 15 hours.

25 . The process according to claim 23 , wherein the artificial aging treatment comprises heating the wrought material at a temperature of 145° C. to 180° C. for 1 hour to 24 hours.

Assignees

• Uacj Corp

Inventors

• HATTA Hidenori
• UDAGAWA Satoshi
• Watanabe Takero

Classifications

• C22F1/053 Primary

  of alloys with zinc as the next major constituent · CPC title

• C22F1/047

  of alloys with magnesium as the next major constituent · CPC title

• C22F1/002

  by rapid cooling or quenching; cooling agents used therefor · CPC title

• C22C21/10 Primary

  with zinc as the next major constituent · CPC title

• C22C21/06

  with magnesium as the next major constituent · CPC title