US20100012236A1 - Heat treatment method of aluminum alloy panel - Google Patents

Heat treatment method of aluminum alloy panel Download PDF

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Publication number
US20100012236A1
US20100012236A1 US12/356,439 US35643909A US2010012236A1 US 20100012236 A1 US20100012236 A1 US 20100012236A1 US 35643909 A US35643909 A US 35643909A US 2010012236 A1 US2010012236 A1 US 2010012236A1
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United States
Prior art keywords
aluminum alloy
occurred
alloy panel
heat treatment
panel
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Abandoned
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US12/356,439
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English (en)
Inventor
Seung Hyun Hong
Yoo Dong Chung
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Hyundai Motor Co
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Hyundai Motor Co
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Publication date
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Assigned to HYUNDAI MOTOR COMPANY reassignment HYUNDAI MOTOR COMPANY ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: CHUNG, YOO DONG, HONG, SEUNG HYUN
Publication of US20100012236A1 publication Critical patent/US20100012236A1/en
Abandoned legal-status Critical Current

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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
    • C22F1/047—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 of alloys with magnesium as the next major constituent
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21B—ROLLING OF METAL
    • B21B3/00—Rolling materials of special alloys so far as the composition of the alloy requires or permits special rolling methods or sequences ; Rolling of aluminium, copper, zinc or other non-ferrous metals
    • 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
    • C22C21/06—Alloys based on aluminium with magnesium as the next major constituent

Definitions

  • the present invention relates to a heat treatment method of an aluminum alloy panel. More particularly, the present invention relates to a heat treatment method of an aluminum alloy panel, which can prevent the formation of surface curvature that can occur when the aluminum alloy panel is molded.
  • Aluminum alloys used for vehicle outer panels are 5xxx (aluminum-magnesium) and 6xxx (aluminum-magnesium-silicon) series alloys, and the panels are formed to have a thickness up to 2 mm to increase strength and hardness.
  • the aluminum-magnesium alloys are superior to the aluminum-magnesium-silicon alloys and are applied to inner and outer panels having a complicated shape.
  • the aluminum-magnesium alloy sheets have a problem in that they show stretcher-strain mark formed on the surfaces thereof due to the interaction between dislocations that cause plastic deformation and precipitates of Al—Si during stamping or other deformations, i.e. due to dynamic strain aging and inhomogeneous deformation around precipitates by the precipitation of the alloy elements added to obtain high elongation and high formability by straining during deformation, thus deteriorating the surface quality of the sheets.
  • the surface waviness can be characterized by the occurrence of serrated flow on a tension curve from tensile test on panel materials.
  • a prior art method to solve the problem of surface waviness is to subject an outer panel having such surface waviness to a post-process of sanding the front surface of the outer panel.
  • the method reduces the productivity and increases the manufacturing cost.
  • the outer panel is prepared by using an aluminum-magnesium alloy containing a high content of Mg coupled with a pose-process of sanding the front surface of the panel.
  • the present invention provides a heat treatment method of an aluminum alloy panel, the method comprising: cold rolling an aluminum alloy panel at a reduction ratio of 45 to 50% at a final pass in a cold rolling process; first heat-treating the cold-rolled aluminum alloy panel at 450 to 510° C. for 3 hours; rapidly cooling the heat-treated aluminum alloy panel at a rate more than 60° C./sec after the first heat treatment; and second heat-treating the rapidly cooled aluminum alloy panel at 200 to 220° C.
  • the aluminum alloy panel is an AA5454 aluminum-magnesium alloy panel comprising 95.35-96.45 wt % of aluminum (Al), 3.0 to 3.8 wt % of magnesium (Mg), 0.2 to 0.5 wt % of manganese (Mn), 0.35 wt % of iron (Fe).
  • the aluminum alloy panel is cold-rolled at a reduction ratio of 45 to 50% such that shear stress is applied to the surface of the aluminum alloy panel and shear texture ⁇ 001 ⁇ 110> is developed.
  • vehicle or “vehicular” or other similar term as used herein is inclusive of motor vehicles in general such as passenger automobiles including sports utility vehicles (SUV), buses, trucks, various commercial vehicles, watercraft including a variety of boats and ships, aircraft, and the like, and includes hybrid vehicles, electric vehicles, plug-in hybrid electric vehicles, hydrogen-powered vehicles and other alternative fuel vehicles (e.g. fuels derived from resources other than petroleum).
  • a hybrid vehicle is a vehicle that has two or more sources of power, for example both gasoline-powered and electric-powered vehicles.
  • FIG. 1 is a graph showing the formation of surface waviness, obtained as a result of a tensile test for an aluminum alloy panel prepared by a conventional heat treatment method
  • FIG. 2 is a diagram showing textures shown as (111) pole figures after cold rolling of a panel during heat treatment of the present invention
  • FIG. 3 is a graph showing the results of tensile deformation behavior test for an aluminum panel prepared by a heat treatment method of the present invention and an aluminum panel prepared by a conventional heat treatment method;
  • FIG. 4 shows images that compare surface waviness of the aluminum panel prepared by the heat treatment method of the present invention and that of the aluminum panel prepared by the conventional heat treatment method.
  • the present invention provides a heat treatment method in which a simple heat treatment process is applied to an aluminum-magnesium alloy panel in order to reduce surface waviness formed by dynamic strain aging, facilitate the molding process, and obtain high strength characteristics by work hardening after molding.
  • the present invention provides a heat treatment method, which can obtain high strength characteristics after heat treatment due to the formation of precipitates by magnesium (Mg) in an aluminum-magnesium alloy panel and reduce surface roughness during the molding of the panel by performing a heat treatment in a specific temperature range.
  • Mg precipitates by magnesium
  • AA5454 aluminum-magnesium alloy may be used.
  • the AA5454 aluminum-magnesium alloy is a commercially available alloy comprising 95.35-96.45 wt % of aluminum (Al), 3.0 to 3.8 wt % of magnesium (Mg), 0.2 to 0.5 wt % of manganese (Mn), 0.35 wt % of iron (Fe).
  • An AA5454 aluminum-magnesium alloy panel having the above-described composition may be manufactured by a known method.
  • the method comprises: dissolving a raw material in an ingot state and forming an aluminum-magnesium alloy slab having a thickness of 150 mm by DC casting; performing hot rolling at 550° C. to be rolled into a thickness of 20 mm; cold rolling the hot-rolled coil at 420° C. to be rolled into a thickness of 1.0 mm; and performing aging treatment at 450-510° C. for 5 to 7 hours.
  • the aging treatment contributes to increase the moldability of the panel and maximize the elongation; however, it is inevitable that the magnesium precipitates, which cause the formation of surface waviness, become coarse.
  • a maximum shear stress is applied during the cold rolling in order to suppress the growth of magnesium precipitates, thereby preventing the magnesium precipitates from becoming coarse, and a multistage heat treatment is performed so that the precipitates are minutely distributed.
  • the cold rolling process is performed in five passes.
  • the surface shear strain is applied at the final pass of the cold rolling process, what we called shear rolling, applying a rolling thickness strain corresponding to 45 to 50% with respect to the thickness of the previous pass (after fourth pass).
  • shear stress is applied in all passes, grain orientation is changed to ⁇ 001 ⁇ 110>, called shear texture, and thereby the anisotropy is increased. Accordingly, it is necessary that the shear stress should be applied in the final rolling pass.
  • the AA5454 aluminum alloy panel is cold-rolled at a rolling reduction ratio of 45 to 50% at the final pass, the cold-rolled panel is subjected to a first heat treatment process which is performed at 450 to 510° C. for 3 hours, the panel then is rapidly cooled at a rate of 60° C./sec or higher, and the rapidly cooled panel is subjected to a second heat treatment process which is performed at 200 to 220° C.
  • the AA5454 aluminum alloy panel is cold-rolled at a threshold temperature, where magnesium (Mg) precipitated at the grain boundary of the AA5454 aluminum alloy does not grow, any already-formed magnesium precipitates are dissolved by the first heat treatment process, and the magnesium precipitates are finely reprecipitated by the second heat treatment while being prevented from growing.
  • Mg magnesium
  • FIG. 2 is a diagram showing textures shown as (111) pole figures after cold rolling of the panel. It can be seen from FIG. 2 that while a panel prepared by a conventional heat treatment method (A) has ring-shaped texture on the surface and in the inside thereof, a panel prepared by the present heat treatment method (B) has a shear texture ⁇ 001 ⁇ 110> developed on the surface thereof, which delays the growth of magnesium precipitates during the heat treatment and a ring-shaped texture, a typical rolling texture, developed in the inside thereof.
  • FIG. 3 is a graph showing the results of tensile deformation behavior test for an aluminum panel prepared by a heat treatment method of the present invention and an aluminum panel prepared by a conventional heat treatment method. It can be seen from FIG. 3 that unlike the panels prepared by conventional methods (heat-treated at 450° C. or 510° C. for 5 hours), the panel prepared by the present heat to treatment method does not show strain aging, which may mean that the growth of magnesium precipitates is suppressed by the second heat treatment.
  • Strain aging was examined for the panels prepared by the heat treatment method according to the present invention and those prepared by conventional heat treatment methods. The formation of strain aging was checked on tensile curves and examined through surface roughness analysis. The test results are shown in the following Table 1.
  • magnesium precipitates can be prevented from becoming coarse, surface waviness formed by dynamic strain aging during molding of the panel can thereby be reduced, which makes it possible to facilitate the molding process and obtain high strength characteristics by work hardening after molding.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Metal Rolling (AREA)
US12/356,439 2008-07-21 2009-01-20 Heat treatment method of aluminum alloy panel Abandoned US20100012236A1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
KR10-2008-0070424 2008-07-21
KR1020080070424A KR101028029B1 (ko) 2008-07-21 2008-07-21 알루미늄 합금 판재의 열처리 방법

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US20100012236A1 true US20100012236A1 (en) 2010-01-21

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US (1) US20100012236A1 (zh)
KR (1) KR101028029B1 (zh)
CN (1) CN101634004A (zh)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN106435297A (zh) * 2016-11-17 2017-02-22 东莞宜安科技股份有限公司 一种耐弯曲、耐腐蚀的高强度铝镁合金的制备方法及产品
US10301709B2 (en) 2015-05-08 2019-05-28 Novelis Inc. Shock heat treatment of aluminum alloy articles
US11874063B2 (en) 2016-10-17 2024-01-16 Novelis Inc. Metal sheet with tailored properties

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR101509636B1 (ko) * 2012-12-28 2015-04-08 주식회사 포스코 마그네슘 합금 판재의 냉각 장치 및 그 방법

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4820355A (en) * 1987-03-30 1989-04-11 Rockwell International Corporation Method for fabricating monolithic aluminum structures
US5496426A (en) * 1994-07-20 1996-03-05 Aluminum Company Of America Aluminum alloy product having good combinations of mechanical and corrosion resistance properties and formability and process for producing such product

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH0733553B2 (ja) * 1992-03-09 1995-04-12 スカイアルミニウム株式会社 耐応力腐食割れ性に優れた成形加工用アルミニウム合金圧延板およびその製造方法

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4820355A (en) * 1987-03-30 1989-04-11 Rockwell International Corporation Method for fabricating monolithic aluminum structures
US5496426A (en) * 1994-07-20 1996-03-05 Aluminum Company Of America Aluminum alloy product having good combinations of mechanical and corrosion resistance properties and formability and process for producing such product

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US10301709B2 (en) 2015-05-08 2019-05-28 Novelis Inc. Shock heat treatment of aluminum alloy articles
US11874063B2 (en) 2016-10-17 2024-01-16 Novelis Inc. Metal sheet with tailored properties
CN106435297A (zh) * 2016-11-17 2017-02-22 东莞宜安科技股份有限公司 一种耐弯曲、耐腐蚀的高强度铝镁合金的制备方法及产品

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KR20100009683A (ko) 2010-01-29
KR101028029B1 (ko) 2011-04-13
CN101634004A (zh) 2010-01-27

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Owner name: HYUNDAI MOTOR COMPANY,KOREA, REPUBLIC OF

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Effective date: 20081009

STCB Information on status: application discontinuation

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