WO1998035069A1 - Procede pour reduire la formation de stries dans des produits en tole pour automobiles - Google Patents

Procede pour reduire la formation de stries dans des produits en tole pour automobiles Download PDF

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Publication number
WO1998035069A1
WO1998035069A1 PCT/CA1998/000070 CA9800070W WO9835069A1 WO 1998035069 A1 WO1998035069 A1 WO 1998035069A1 CA 9800070 W CA9800070 W CA 9800070W WO 9835069 A1 WO9835069 A1 WO 9835069A1
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WO
WIPO (PCT)
Prior art keywords
sheet
roping
process according
article
cold rolling
Prior art date
Application number
PCT/CA1998/000070
Other languages
English (en)
Inventor
David James Lloyd
Gene Bruce Burger
Daniel Ronald Evans
Alok Kumar Gupta
Original Assignee
Alcan International Limited
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Alcan International Limited filed Critical Alcan International Limited
Publication of WO1998035069A1 publication Critical patent/WO1998035069A1/fr

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Classifications

    • 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
    • C22F1/057—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 copper as the next major constituent
    • 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

Definitions

  • This invention relates to a process of reducing the tendency of aluminum alloy sheet articles to exhibit roping when formed into products, e.g. automotive parts. More particularly, the invention relates to the reduction of roping tendencies in aluminum-magnesium- silicon (i.e. 6000 series) alloy sheet products, and other heat-treatable aluminum alloys (e.g. the 2000 series alloys) typically used for fabricating automotive parts .
  • aluminum-magnesium- silicon (i.e. 6000 series) alloy sheet products and other heat-treatable aluminum alloys (e.g. the 2000 series alloys) typically used for fabricating automotive parts .
  • Aluminum alloys for automotive parts are increasing because of the desirable characteristics of such products, namely their light weight, corrosion resistance and high strength.
  • Aluminum alloys of the 6000 series alloys containing Al-Mg-Si
  • alloys of the 2000 series are often chosen for automotive use, and the usual method of producing the sheet involves direct-chill (DC) casting, homogenising, hot rolling, cold rolling, solution heat treatment and possibly additional steps such as aging and levelling. This produces an aluminum sheet product in the so-called T4 temper.
  • roping may be inhibited by modifying the production method so that complete recrystallisation occurs at an intermediate stage of processing.
  • Several methods can potentially achieve this result, such as batch annealing for 1 hour at 400°C at an intermediate gauge.
  • batch annealing tends to result in the formation of coarse Mg 2 Si precipitates, which are difficult to redissolve during continuous heat treatment solutionizing (which involves heating characterized by a rapid thermal spike rather than sustained heating) .
  • the intermediate annealing is then followed by cold rolling (or the remainder of the cold rolling steps) to final gauge, solution heat treatment, levelling and eventually forming into the desired automotive product.
  • An object of the present invention is to provide an improved method of reducing or inhibiting roping tendencies in aluminum alloy sheet products .
  • Another object of the invention is to provide an improved process of reducing or inhibiting roping tendencies in 6000 series or 2000 series aluminum alloy sheet products.
  • Another object of the invention is to provide a method of reducing or inhibiting roping tendencies in aluminum automotive sheet articles without disturbing conventional hot rolling and cold rolling treatment steps carried out during the conventional production of such sheet articles.
  • a process of producing an aluminum alloy sheet article having a reduced tendency to exhibit roping in products formed from said sheet article comprising the steps of: direct chill casting a heat-treatable aluminum alloy having a tendency to exhibit roping, to form a cast ingot; homogenizing said cast ingot to produce an homogenized cast ingot; hot rolling the homogenized cast ingot to produce an intermediate hot-rolled sheet article; cold rolling the intermediate hot-rolled sheet article to final gauge; and subjecting said sheet article of final gauge to a solutionizing step; wherein said process includes a step, carried out during or after said cold rolling and before said solutionizing step, of subjecting a sheet article to a recovery anneal comprising heating said sheet article to a temperature in a range of 300 to 350°C for 2 to 16 hours.
  • recovery anneal we mean an annealing step that has the effect of recovering the deformation structure of the alloy to give a combination of texture components that minimize roping tendencies of the final sheet article.
  • a recovery anneal differs from a "full anneal” in that the latter causes complete recrystallization to produce a stable grain structure, whereas the former does not .
  • the recovery anneal may be carried out after the cold rolling has been completed, or if the cold rolling involves several rolling steps, the recovery anneal may be carried out after a first of the cold rolling steps but before the final cold rolling step.
  • the invention also relates to sheet articles of reduced roping tendency thus produced, and products formed from such sheet articles.
  • the alloy is a 6000 series aluminum alloy (containing aluminum, magnesium and silicon), e.g.
  • AA6111, AA2036, AA6010, AA6016 and AA6022 is most preferably the AA6111 alloy.
  • the process is also effective for heat-treatable 2000 series alloys (a heat-treatable alloy is one which exhibits increased strength due to precipitation when held at elevated temperature) .
  • the process of the invention has the advantage that the recovery anneal is carried out on sheet of the final gauge, or close to final gauge, so that the capacity of the rolling line does not have to be increased.
  • Figures 1A, IB, 1C and ID are each photomicrographs showing the dislocation structures of aluminum sheet products following a recovery anneal carried out at 300°C for periods of time of 1 hour, 2 hours, 5 hours and 16 hours, respectively;
  • Figure 2 is a graph showing the volumes of various crystallographic components of aluminum sheet products (alloy AA6111) after various treatments, i.e. after conventional cold-rolling, in T4 temper and in T4 temper following a recovery anneal (Rec Ann) according to the present invention.
  • Figure 3 is a photograph showing two aluminum alloy sheet products positioned side by side, one having been produced by a standard method (left hand product) and the other having been treated to a recovery anneal according to the present invention (right hand product) . Both sheets were strained at 10 to 15% in the transverse direction and then rubbed with a polishing stone to reveal high and low points in surface topography.
  • the present invention inhibits roping by employing a recovery anneal at final gauge, or close to final gauge, prior to the conventional solution heat treatment employed during the manufacture of sheet product suitable for automobile part manufacture.
  • a recovery anneal cold rolled sheet, produced by a standard hot and cold rolling route, is partially annealed (referred to as a recovery anneal) prior to the normal solution heat treatment (usually carried out on a continuous heat treatment line) .
  • the recovery anneal of the present invention does not have to be carried out on final gauge material to be effective, and instead may be carried out between two cold rolling steps. Such a treatment prevents roping provided the reduction in thickness is limited to about 30% or less (preferably about 20% or less) during the final cold rolling carried out between the recovery anneal and the continuous annealing and solution heat treatment.
  • the final cold rolling to gauge after the recovery anneal produces a product which is stronger when it commences the continuous annealing and solution heat treatment, and so is less susceptible to dings and damage during handling. Moreover, a more desirable finer grained final product is produced than is the case when the recovery anneal is carried out on the final gauge material .
  • a typical example of a recovery anneal carried out on AA6111 alloy between cold rolling steps involves hot rolling a DC cast ingot to one tenth inch, cold rolling to an intermediate gauge, recovery annealing at the intermediate gauge for about 4 hours at about 300°C, subjecting the intermediate product to a 20% reduction cold roll, and then subjecting the alloy to a continuous annealing and solution heat treatment.
  • steps of direct chill casting, hot rolling, cold rolling and solutionizing also employed in the present invention may be conventional.
  • suitable steps are disclosed in US patent No. 5,616,189, issued on April 1, 1997 to Jin et al . and assigned to the same assignee as the present application.
  • Suitable steps are also disclosed in US patent 5,480,498 mentioned above. The disclosure of both these patents are incorporated herein by reference.
  • the alloy may be DC-cast using practices common in the industry.
  • the resulting ingot is then homogenized at 540-580°C for a period of 4 to 16 hours, and then directly hot rolled to an intermediate gauge of 2.5 to 8 mm.
  • This intermediate gauge sheet is then cold rolled to a final gauge of approximately 1 mm, and then solutionized on a continuous annealing line, achieving a maximum temperature of 540-570°C, followed by rapid cooling.
  • the recovery anneal is preferably carried out prior to the final cold rolling step.
  • the recovery anneal of the present invention involves a lower temperature heat treatment which is designed to recover the dislocation structure, and to generate texture components which will survive the subsequent solution heat treatment at the final gauge, and hence avoid the generation of spatial correlated "hard" texture components.
  • the recovery anneal should produce a structure in which the cube and rotated cube components are each present on a global scale in amounts of approximately 5% by volume or more and the Goss component is present similarly in amounts of less than approximately 3% by volume of the sheet article of final gauge following the solutionizing.
  • T8X temper refers to a sheet product that has been deformed in tension by 2% followed by a 30 minute treatment at 177°C to represent the forming plus paint curing treatment typically experienced by automotive panels
  • X UTS stands for ultimate tensile strength. This is the maximum stress attained in a tensile sample during a uniaxial tensile test. At strains beyond this point, continued deformation is confined to a small region in the tensile sample, called the neck.
  • Yield strength is the stress at which plastic flow initiates in a material. At this point, the entire volume of material is deforming plastically. It is usually defined by the 0.2% offset criterion, given by the stress at which the strain deviates from linear elastic stress-strain behaviour by 0.2%.
  • the alloy was cold rolled to different reductions, given a recovery anneal of (a) 5 hours at 300°C and (b) 12 hours at 300°C, followed by cold rolling to 1 mm final gauge and solution treated.
  • Table 3 shows the results for different reductions between the recovery anneal and the final solution treatment. The roping tendency and fine grain size were then measured.
  • roping is thought to reflect the spatial distribution of "hard” and “soft” crystallographic texture components in the sheet. While at present there are no techniques available which can provide an exact description of the three-dimensional spatial distribution of texture components in a product, it is of interest to examine the microstructural changes occurring during the recovery anneal and the global texture distributions developed as a result of this processing route.
  • Figures 1A, IB, 1C and ID of the accompanying drawings show the dislocation structure after different recovery annealing times at 300°C.
  • the recovery anneal produces a rearrangement of the dislocation structure to a well recovered, fine scale sub-grain structure which is stabilized to some extent by the incoherent precipitates, the majority of which has been formed during the prior hot rolling.
  • the incoherent precipitates the majority of which has been formed during the prior hot rolling.
  • the occasional sub- grain had coarsened significantly, indicating that recrystallisation to produce a stable grain structure is just beginning.
  • Figure 2 of the accompanying drawings shows the different global texture components developed in the test .
  • the Figure presents volume fractions of texture components calculated from the global texture distributions evaluated for AA6111 sheet processed through two processing routes, and compares them with that of the cold-rolled sheet.
  • the alloy in all cases was similar, i.e. at the same nominal composition within the AA6111 composition range.
  • the texture of the cold-rolled sheet was obtained after cold rolling the sheet through a 63% reduction in thickness. Cold rolling was carried out directly after hot rolling.
  • coil 11035 was directly passed through the solution heat treatment (SHT) line, and it is the texture in this T4 condition (i.e. following SHT and natural aging at room temperature) which was evaluated and presented in Figure 2.
  • SHT solution heat treatment
  • Coil 43522 following cold rolling, was subsequently given a recovery anneal ( "Rec Ann") treatment at 300°C for 4 hours. The coil was then passed through the solution heat treatment line. The texture of this coil in the T4 condition was evaluated and the results of the analysis given in Figure 2.
  • the Figure shows that the recovery anneal generates a significant volume fraction of cube texture, which is retained after the solution treatment.
  • included in this Figure for comparison is the texture developed in material produced by conventional cold rolling, and material in conventional T4 temper.
  • Figure 3 compares the stoned surface of conventionally processed sheet with sheet subjected to a recovery anneal .
  • the lack of roping in the latter product is apparent .
  • the experiments also suggest that the process of the invention is quite robust in that the time window can be as large as 16 hours at 300°C, and for shorter times the temperature can be as high as 350°C.
  • work done to date indicates that the process can tolerate up to a 30% cold reduction (more preferably a 25% cold reduction, and ideally about 20% cold reduction) between the recovery anneal and the solution treatment without introducing significant roping in the final T4 sheet.
  • the tensile properties of the final T4 sheet are equivalent to those of standard AA6111-T4 sheet processed without any heat treatment at intermediate gauge .
  • Total Elongation is the elongation achieved in a tensile sample up to the point of failure. This includes the contribution of both uniform elongation and the straining which occurs in the neck region of the sample.
  • n Value is the strain hardening exponent. This is obtained by fitting an exponential function to the experimental stress-strain curve, for stresses up to the UTS level.
  • the R value is the plastic strain ratio, given by the ratio of the width strain to thickness strain which develops during a tensile test on a sheet test sample.
  • the final sheet was roping-free as evaluated by a 15% stretch and stoning. It was also free of roping when tested in plane strain and in balanced biaxial dome tests .
  • the Erichsen test is a ball punch deformation test used to evaluate the ductility of metallic sheet materials . It involves near-biaxial stretching of a constrained test specimen, utilizing a ball indentor diameter and die geometry as given in ASTM specification E643-84 (Reapproved 1995) . Erichson cup heights are given in millimeters.
  • the balanced biaxial dome test is used to evaluate the ductility of metallic sheet materials under conditions of biaxial stress (in the plane of the sheet) in which the stresses in the two principal stretching directions are equal .
  • the testing procedure involves a large punch with a spherical contact geometry. Dome heights are given in millimeters, as the displacement which the punch moves through from contact with the sheet until initial fracture occurs. This displacement is dependent upon the dimensions of the punch and sample fixture.

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  • Chemical & Material Sciences (AREA)
  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Mechanical Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Metal Rolling (AREA)

Abstract

Ce procédé permet de produire des articles en tôle en alliage d'aluminium ayant moins tendance à présenter des stries dans les produits fabriqués à partir de ces articles. Ce procédé consiste à effectuer le coulage en coquille direct d'un alliage en aluminium thermotraitable, ayant tendance à présenter des stries, afin de former un lingotin de coulée, à homogénéiser le lingotin de coulée, à laminer à chaud le lingotin de coulée ainsi homogénéisé, à laminer à froid le lingotin de coulée laminé à chaud intermédiaire, afin de produire un article en tôle de calibre final, et à soumettre l'article en tôle de calibre final à une opération de traitement en solution. L'étape la plus importante de ce procédé, effectuée pendant ou après le laminage à froid mais avant l'opération de traitement en solution, consiste à soumettre l'article en tôle à un recuit de restauration, en le chauffant à une température comprise entre 300 et 350 °C pendant 2 à 16 heures. Le recuit de restauration modifie la structure cristallographique de l'article en tôle, celui-ci ayant ainsi moins tendance à présenter des stries, lorsqu'il est formé en un produit, par exemple pour pièces d'automobiles. Cette invention se rapporte également à des articles en tôle produits par ce procédé et à des produits formés fabriqués à partir de ces articles en tôle.
PCT/CA1998/000070 1997-02-05 1998-02-03 Procede pour reduire la formation de stries dans des produits en tole pour automobiles WO1998035069A1 (fr)

Applications Claiming Priority (2)

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US3738097P 1997-02-05 1997-02-05
US60/037,380 1997-02-05

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Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1029937A1 (fr) * 1998-09-10 2000-08-23 Kabushiki Kaisha Kobe Seiko Sho FEUILLE EN ALLIAGE Al-Mg-Si
WO2000052219A1 (fr) * 1999-03-01 2000-09-08 Alcan International Limited Procede de fabrication d'une feuille d'aluminium aa6000
NL1022754C2 (nl) * 2003-02-21 2004-08-24 Corus Technology B V Gewalst product, zoals plaat of band, uit aluminium en roestvast staal.
EP1967598A1 (fr) * 2001-03-28 2008-09-10 Sumitomo Light Metal Industries, Ltd. Feuille d'alliage d'aluminium dotée d'excellentes formabilité et trempabilité par cuisson de peinture et procédé pour sa production
WO2016115120A1 (fr) * 2015-01-12 2016-07-21 Novelis Inc. Tôle d'aluminium hautement déformable pour l'industrie automobile à striage réduit ou nul et procédé de préparation
WO2021114967A1 (fr) * 2019-12-10 2021-06-17 江苏大学 Procédé de préparation de matériau composite à base d'aluminium renforcé in situ par des nanoparticules ternaires

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0099739A2 (fr) * 1982-07-15 1984-02-01 Continental Can Company, Usa, Inc. Alliage à base d'aluminium et son procédé de fabrication
US5480498A (en) * 1994-05-20 1996-01-02 Reynolds Metals Company Method of making aluminum sheet product and product therefrom

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0099739A2 (fr) * 1982-07-15 1984-02-01 Continental Can Company, Usa, Inc. Alliage à base d'aluminium et son procédé de fabrication
US5480498A (en) * 1994-05-20 1996-01-02 Reynolds Metals Company Method of making aluminum sheet product and product therefrom

Cited By (20)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1029937A1 (fr) * 1998-09-10 2000-08-23 Kabushiki Kaisha Kobe Seiko Sho FEUILLE EN ALLIAGE Al-Mg-Si
EP1029937A4 (fr) * 1998-09-10 2002-10-02 Kobe Steel Ltd FEUILLE EN ALLIAGE Al-Mg-Si
EP1788103A2 (fr) * 1998-09-10 2007-05-23 Kabushiki Kaisha Kobe Seiko Sho Feuille d'alliage à base de Al-Mg-Si
EP1788103A3 (fr) * 1998-09-10 2007-06-06 Kabushiki Kaisha Kobe Seiko Sho Feuille d'alliage à base de Al-Mg-Si
WO2000052219A1 (fr) * 1999-03-01 2000-09-08 Alcan International Limited Procede de fabrication d'une feuille d'aluminium aa6000
US6652678B1 (en) 1999-03-01 2003-11-25 Alcan International Limited AA6000 aluminum sheet method
EP1967598A1 (fr) * 2001-03-28 2008-09-10 Sumitomo Light Metal Industries, Ltd. Feuille d'alliage d'aluminium dotée d'excellentes formabilité et trempabilité par cuisson de peinture et procédé pour sa production
NL1022754C2 (nl) * 2003-02-21 2004-08-24 Corus Technology B V Gewalst product, zoals plaat of band, uit aluminium en roestvast staal.
WO2004073899A2 (fr) * 2003-02-21 2004-09-02 Corus Technology Bv Produit lamine tel qu'une plaque, une feuille ou une bande, compose d'aluminium et d'acier inoxydable
WO2004073899A3 (fr) * 2003-02-21 2004-11-18 Corus Technology Bv Produit lamine tel qu'une plaque, une feuille ou une bande, compose d'aluminium et d'acier inoxydable
WO2016115120A1 (fr) * 2015-01-12 2016-07-21 Novelis Inc. Tôle d'aluminium hautement déformable pour l'industrie automobile à striage réduit ou nul et procédé de préparation
CN107109547A (zh) * 2015-01-12 2017-08-29 诺维尔里斯公司 表面条痕减少或无表面条痕的高度可成形的汽车铝片材以及制备方法
US9828652B2 (en) 2015-01-12 2017-11-28 Novelis Inc. Highly formable automotive aluminum sheet with reduced or no surface roping and a method of preparation
RU2699496C2 (ru) * 2015-01-12 2019-09-05 Новелис Инк. Автомобильный алюминиевый лист высокой формуемости с уменьшенной или отсутствующей бороздчатостью поверхности и способ его получения
EP3540085A1 (fr) * 2015-01-12 2019-09-18 Novelis Inc. Tôle d'aluminium hautement déformable pour l'industrie automobile à striage réduit ou nul et procédé de préparation
EP3950987A1 (fr) * 2015-01-12 2022-02-09 Novelis, Inc. Tôle d'aluminium hautement déformable pour l'industrie automobile à striage réduit ou nul et procédé de préparation
CN115109972A (zh) * 2015-01-12 2022-09-27 诺维尔里斯公司 表面条痕减少或无表面条痕的高度可成形的汽车铝片材以及制备方法
EP4245881A3 (fr) * 2015-01-12 2024-01-03 Novelis, Inc. Tôle d'aluminium hautement déformable pour l'industrie automobile à striage réduit ou nul et procédé de préparation
WO2021114967A1 (fr) * 2019-12-10 2021-06-17 江苏大学 Procédé de préparation de matériau composite à base d'aluminium renforcé in situ par des nanoparticules ternaires
US11761059B2 (en) 2019-12-10 2023-09-19 Jiangsu University Preparation method of in-situ ternary nanoparticle-reinforced aluminum matrix composite

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