US20230083429A1 - Method and installation for producing aluminum can sheet - Google Patents

Method and installation for producing aluminum can sheet Download PDF

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US20230083429A1
US20230083429A1 US17/908,974 US202117908974A US2023083429A1 US 20230083429 A1 US20230083429 A1 US 20230083429A1 US 202117908974 A US202117908974 A US 202117908974A US 2023083429 A1 US2023083429 A1 US 2023083429A1
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cold
hot
mill
sheet
rolled sheet
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Ioannis Tsiros
Dionysios Spathis
Michael Stassinopoulos
Andreas Mavroudis
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Hellenic Research Centre For Metals SA
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Hellenic Research Centre For Metals SA
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Assigned to Hellenic Research Centre for Metals S.A. reassignment Hellenic Research Centre for Metals S.A. ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: Mavroudis, Andreas, Spathis, Dionysios, Stassinopoulos, Michael, Tsiros, Ioannis
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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
    • 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
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
    • C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
    • C21D8/0221—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the working steps
    • C21D8/0226—Hot rolling
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
    • C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
    • C21D8/0221—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the working steps
    • C21D8/0236—Cold rolling
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
    • C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
    • C21D8/0247—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the heat treatment
    • C21D8/0273—Final recrystallisation annealing
    • 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

  • This disclosure relates to a method of producing aluminum can sheet and an installation configured to perform the method.
  • earing When aluminum can sheet is formed into cup-shaped articles, a phenomenon known as “earing” usually occurs to some extent. Earing can be observed as a wave-shaped appearance around the top edge of the formed cup. The wave-like protruding portions, also known as “ears,” are formed during the deep drawing step in the fabrication of the cup and represent an undesirable feature of the article.
  • CBS aluminum can body stock
  • the cup In aluminum can body stock (CBS), the cup is subsequently ironed in multiple rings which can accentuate the wavy ears. High earing can create transport problems with the cup as well as insufficient trim after ironing, clipped ears, and trimmer jams. These artefacts are not desirable in aluminum can manufacturing. Thus, it is desired to minimize earing to avoid these problems and to increase the quality of the cup.
  • can body stock material such as AA3004, AA3104 or other aluminum alloy is basically suitable for making aluminum can sheet with low earing characteristics provided that a suitable manufacturing process can be established.
  • US 2002/0062889 A1 discloses a process and a plant for producing hot-rolled aluminum strip for can making.
  • the plant includes a reversing roughing stage for the feed material, which is used hot, and immediately thereafter finishing rolling of the strip, which is followed by heat treatment of the strip coiled up into coils.
  • recrystallization in the rolled material is suppressed by controlled temperature management of the hot strip. Temperature is maintained in the noncritical temperature range of 260° C. to 280° C. to avoid recrystallization. The recrystallization is brought about only outside the rolling train. For this purpose, the hot rolled material is transferred to a continuous furnace directly following the finishing rolling.
  • the direct transfer brings about the advantage that a furnace used for recrystallization only has to apply a relatively small temperature difference (e.g., about 40° C.-60° C.) between the rolling temperature and the recrystallization temperature, and thus achieves a favorable energy balance.
  • a relatively small temperature difference e.g., about 40° C.-60° C.
  • WO 2015/140833 A1 discloses aluminum alloy sheets having a low earing rate suitable for making aluminum can bodies.
  • the alloys mentioned for this purpose include type A3004 and A3104 alloys.
  • a preferred process includes the process steps of casting the ingot, homogenizing the ingot, hot rolling, primary cold rolling, intermediate annealing, and secondary cold rolling.
  • the hot rolling step is divided into two separate steps, namely “hot rough rolling step” and “hot finish rolling step.”
  • the end temperature is preferably between 330° C. and 380° C. It is observed that the driving force of recrystallization is insufficient if the end temperature is less than 330° C.
  • a method of producing aluminum can sheet including providing a body made of an aluminum alloy type AA3004, AA3104 or other aluminum alloy suitable for making aluminum can sheet; heating the body to a homogenization temperature; hot rolling the body in a hot rolling mill to produce a hot rolled sheet, the hot rolled sheet exiting the hot rolling mill at a hot rolling exit temperature with a hot mill exit gauge, wherein the hot rolling exit temperature is selected to substantially avoid recrystallization of the hot rolled sheet; cold rolling the hot rolled sheet in a cold rolling mill to apply a cold reduction to produce a cold rolled sheet with a cold mill exit gauge smaller than the hot mill exit gauge; annealing the cold rolled sheet in an intermediate temperature range selected to allow recrystallization of the cold rolled sheet to obtain a recrystallized annealed sheet; and cold rolling the recrystallized annealed sheet to apply a cold reduction to produce a cold rolled sheet with a final gauge.
  • we also provide an installation that produces aluminum can sheet according to the method of producing aluminum can sheet including providing a body made of an aluminum alloy type AA3004, AA3104 or other aluminum alloy suitable for making aluminum can sheet; heating the body to a homogenization temperature; hot rolling the body in a hot rolling mill to produce a hot rolled sheet, the hot rolled sheet exiting the hot rolling mill at a hot rolling exit temperature with a hot mill exit gauge, wherein the hot rolling exit temperature is selected to substantially avoid recrystallization of the hot rolled sheet; cold rolling the hot rolled sheet in a cold rolling mill to apply a cold reduction to produce a cold rolled sheet with a cold mill exit gauge smaller than the hot mill exit gauge; annealing the cold rolled sheet in an intermediate temperature range selected to allow recrystallization of the cold rolled sheet to obtain a recrystallized annealed sheet; and cold rolling the recrystallized annealed sheet to apply a cold reduction to produce a cold rolled sheet with a final gauge, including a preheating furnace for heating
  • FIG. 1 shows a schematic illustration of a portion of an installation configured to manufacture aluminum can sheet suitable for making cup-shaped articles.
  • FIG. 2 shows a diagram illustrating the relation between the degree of recrystallization of the sheet material after the initial hot rolling step and the amount and type of earing after applying cold reduction to the final gauge.
  • FIG. 3 shows a diagram illustrating the influence of cold reduction prior to the intermediate annealing and the effect on the type and degree of earing after cold reduction to the final gauge.
  • a body (also denoted as ingot) made of an aluminum alloy is provided.
  • the aluminum alloy is selected so that it is suitable for making aluminum can sheet.
  • the aluminum alloy is of type AA3004, AA3104 or other aluminum alloy suitable for making aluminum can sheet such as AA3204 alloy.
  • Typical requirements for aluminum alloys suitable for making aluminum can sheet are described, for example, in “AlMn1Mg1 for Beverage Cans” by J. Hirsch in: “Virtual Fabrication of Aluminium Products” Wiley-VCH 2006 (ISBN: 3-527-31363-X), chapter 1-4.
  • the material must provide a desired combination of strength and sufficient forming properties.
  • aluminium (aluminum) strength is achieved by the combination of appropriate alloy addition for best solid solution hardening (e.g., by Mg and Mn) and pre-deformation (i.e., highly rolled sheet). Furthermore, strength must remain sufficiently high also after the subsequent paint baking cycles.
  • aluminum alloys comprising the following chemical compositions are used (all numbers in wt %): about 0.05-0.60 wt % Si (Silicon), preferably 0.15-0.5 wt % Si; about 0.10-0.80 wt % Fe (Iron), preferably 0.25-0.70 wt % Fe; about 0.70-1.50 wt % Mn (Manganese), preferably 0.80-1.40 wt % Mn; about 0.80-1.50 wt % Mg (Magnesium), preferably 0.90-1.30 wt % Mg; about 0.05-0.25 wt % Cu (Copper), preferably 0.10-0.25 wt % Cu; up to 0.10 wt % Ti (Titanium); up to 0.25 wt % Zn (Zinc); and up to 0.15 wt % impurities, preferably each of the impurities with less than 0.05 wt %; with the remainder as
  • aluminum alloys used for other purposes are not considered suitable for making aluminum can sheet in the context of this application.
  • Those include, for example, 1XXX series alloys (essentially pure aluminium with a minimum 99% aluminium content by weight), 2XXX series alloys alloyed with copper as a basic alloying element and capable of being precipitation hardened to strengths comparable to steel, 4XXX series alloys alloyed with silicon as a basic alloying element, 5XXX series alloys alloyed with magnesium as a basic alloying element to offer superb corrosion resistance, 6XXX series alloys alloyed with magnesium and silicon as basic alloying elements, 7XXX series alloys alloyed with zinc as a basic alloying element and capable of precipitation hardening, or 8XXX series are alloyed with other elements which are not covered by other series such as Aluminium-lithium alloys.
  • compositions of AA3004, AA3104, AA3204 or other aluminum alloy suitable for making aluminum can sheet as well as other aluminum alloys are known and available, e.g., in the Teal sheets of the Aluminum Association.
  • the body can be made of cast aluminum, which has subsequently been scalped to obtain a body suitable for further processing.
  • the body is heated to a homogenization temperature.
  • the main purpose of this heating step is to homogenize the material. Homogenization temperatures may be about 500° C. to about 600° C., for example, depending on the desired temperature for the next process step.
  • the body may be cooled down to temperatures suitable for hot rolling.
  • the body is hot rolled in a hot rolling mill to produce a hot rolled sheet.
  • the hot rolled sheet exiting the hot rolling mill exits the hot rolling mill at a hot rolling exit temperature.
  • the hot rolling step produces a hot rolled sheet having a hot mill exit gauge, which is the thickness of the rolled aluminum sheet after hot rolling.
  • temperature control is made such that the hot rolling exit temperature is selected to substantially avoid recrystallization of the hot rolled sheet.
  • the term “recrystallization” refers to a process by which deformed grains in a metallic body are replaced by a new set of grains that are essentially free of defects and nucleate and grow until the original grains have been entirely consumed.
  • Recrystallization reduces the strength and hardness of the material while at the same time the ductility is increased.
  • the hot rolling exit temperature is selected such that the sheet exiting the hot rolling mill exhibits a high density of defects such as dislocations and the like and relative high strength and hardness, while at the same time ductility may be relatively low.
  • the substantially un-recrystallized sheet after hot rolling may exhibit a tensile strength of 190 MPa to 240 MPa, for example, while the same material would exhibit significantly lower tensile strength values in a recrystallized state, for example, down to about 150 MPa for the fully recrystallized material.
  • Hardness values may be determined by the Vickers hardness test and may then be expressed as the Vickers Pyramid Number (HV) given in MPa (or N/mm 2 ). Hardness can also be approximated from ultimate tensile strength (UTS) values by the well-known relation for aluminum alloys UTS ⁇ 3*HV.
  • the hot rolled sheet is cold rolled in a cold rolling mill.
  • the purpose of this process step is to achieve a cold reduction, meaning that the gauge (or thickness) of the sheet is further reduced.
  • the cold reduction is performed to produce a cold rolled sheet having a cold mill exit gauge which is smaller than the hot mill exit gauge.
  • Cold rolling follows the hot rolling step, after the sheet has cooled down to temperatures of approximately 100° C. or lower, e.g., as low as 50° c. to 60° C.
  • the cold rolled sheet (having the cold mill exit gauge) is then transferred to a furnace to anneal the cold rolled sheet in an intermediate temperature range with temperatures selected to allow recrystallization of the cold rolled sheet.
  • the annealing step results in a recrystallized sheet having the cold mill exit gauge.
  • the microstructure of the recrystallized sheet typically exhibits a new set of relative defect-free grains replacing the defective microstructure obtained by cold rolling.
  • tensile strength values may be 150 MPa to about 200 MPa, for example.
  • the recrystallized sheet is cold rolled to apply a cold reduction to produce a cold rolled sheet with a final gauge, the final gauge being smaller than the cold mill exit gauge.
  • the hot rolling exit gauge from a single stand reversing mill may typically range down to values about 2.0 mm. Producing lower exit gauge from a single stand reversing mill is generally difficult and may not be feasible due to difficulties in controlling crown, wedge and flatness of the sheet.
  • the tendency of the can-makers is to reduce the thickness of the can sheet, this tendency also known as “down-gauging.” If it is desired to produce a lower thickness final product with similar earing and strength properties compared to nowadays usual thicknesses it is required to keep the same total cold reduction applied to the material after intermediate annealing at hot gauge thickness (either self-annealing or batch annealing). Achieving this goal requires lowering the hot mill exit gauge to values significantly below 2 mm. Our process is capable of substantially avoiding these problems identified in conventional processes.
  • the final product generally exhibits relatively low earing values.
  • the resulting ears are more pronounced at about 45° (relative to the rolling direction).
  • This earing orientation is usually preferable from the final customer's point of view, i.e., from the point of view of the can maker.
  • the new method generally avoids or reduces high ears at 0°/90° which are not desirable from the can maker's point of view and which are very likely obtained with the process described in the prior art such as U.S. Pat. No. 5,362,340.
  • the final strength of the material and the earing is highly dependent from the amount of cold work after intermediate annealing at hot gauge. For example, if, in a conventional process, a material with final gauge 0.26 mm is produced, the intermediate annealing may be performed at about 2 mm gauge. Therefore, the total cold reduction is about 87%. However, if a final customer asks for 0.24 mm final gauge, to produce the same earing and properties it is necessary to make the intermediate annealing at about 1.85 mm. This relatively small thickness often cannot be achieved satisfactorily in a single stand reversing mill due to flatness and thickness range limitations. These limitations do not exist in our method.
  • advantages of our process result at least partly from the fact that cold rolling is performed in two separate steps, wherein the first cold rolling step is performed after hot rolling and before intermediate annealing (on the un-recrystallized material) and the second cold rolling step is performed after the recrystallization annealing (at intermediate temperature) on a material which is recrystallized.
  • first cold rolling step is performed after hot rolling and before intermediate annealing (on the un-recrystallized material)
  • the second cold rolling step is performed after the recrystallization annealing (at intermediate temperature) on a material which is recrystallized.
  • a single stand reversing mill is used as a hot rolling mill in a preferred example of our process and installation. While a tandem mill can be used instead of a single stand reversing mill to perform the hot rolling step, use of a single stand reversing mill is typically much less expensive so that the final product can be made in an economical fashion.
  • the single stand reversing mill is utilized in two different operation modes, wherein a first operation mode includes one or more flat passes and a second operation mode, utilized after the first operation mode, includes one or more coiling passes producing coiled sheet having the hot mill exit gauge.
  • the hot rolling step shall be performed such that recrystallization of the hot rolled sheet is substantially avoided.
  • the hot rolling exit temperature is about 200° C. to about 320° C., with preferred hot rolling exit temperatures being lower than 290° C.
  • aluminum alloys of type AA3004, AA3104 or other aluminum alloys suitable for making aluminum can sheet these temperatures are usually suitable to avoid recrystallization completely, which enhances the advantages of the overall process.
  • the correct temperatures to avoid recrystallization completely may be selected depending on the alloy type and may differ from alloy to alloy.
  • a cold reduction between 5% and 70% is preferably applied in the cold rolling mill rolling the hot rolled sheet.
  • Cold reductions in this range are particularly capable of enhancing the particle stimulated nucleation (PSN) which is believed to lower the cube texture density in the annealed material.
  • PSN particle stimulated nucleation
  • the cold rolling step can be performed at least in the last rolling passes so that coils of cold rolled sheet are obtained in the single stand reversing mill.
  • a continuous furnace may be used for the annealing step in the intermediate temperature range to obtain the recrystallized sheet.
  • a total reduction of more than 70% is applied to the aluminum sheet between the hot mill exit gauge and the final gauge.
  • the total reduction may be 80% or more or even 85% or more. This is partly due to the fact that cold rolling to reduce the gauge is performed in two steps instead of one single step.
  • sufficiently high strength and formability are amongst the major requirements for aluminum can body sheet.
  • High strength is needed to achieve sufficient structural stability and to avoid buckling of the can base (dome reversal) under high internal pressure.
  • High strength is also needed to obtain stable cans with very thin can wall after ironing.
  • Good formability is required as the material undergoes heavy forming operations.
  • Anisotropic material flow due to the texture of the sheet (controlled by balancing the hot strip cube and cold rolling texture) always forms an uneven rim of the can during the deep drawing and ironing operations. This unevenness is also known as “earing.”
  • Highly uneven cup rims are detrimental for transport of the can bodies or affect the whole process when ears are stretched and clipped off during ironing, leading to machine down time, reducing efficiency.
  • Examples are capable of addressing both requirements in a satisfactory way using an economically feasible production process.
  • FIG. 1 shows a schematic drawing of a portion of an installation 100 configured to manufacture aluminum can sheet suitable for making cup-shaped articles.
  • the schematic figure shows only some of the devices utilized in the production route.
  • the production installation typically includes casting devices to produce large cast ingots from aluminum alloy melt.
  • the cast ingots typically consist of coarse grains with dendrite structure and random texture.
  • Precipitates comprising aluminum and other constituents such as Fe, Mn, and Si are typically distributed inhomogeneously in the cast ingot.
  • the cast ingots are homogenized in a homogenization furnace (also denoted as preheating furnace, not shown in FIG. 1 ).
  • the homogenization treatment is typically accompanied by characteristic changes of the solute content and the precipitation microstructure later affecting recrystallization, grain size and texture during the sheet production.
  • a single stand reversing mill 120 is used for hot rolling in a preferred installation.
  • the single stand reversing mill 120 is capable of being operated in two different operation modes drawn separately in schematic FIG. 1 .
  • HR-FP shown on the left hand side of single stand reversing mill 120
  • the incoming ingots are reduced in thickness using several flat passes where the material is rolled back and forth without being coiled on either side of the rolls.
  • HR-CP shown on the right-hand side of the drawing representing the single stand reversing mill 120
  • coiling reels CR on either side of the mill stand MS are used to coil the sheet SH between coiling passes performed in mutually opposite rolling directions.
  • one of the reels is operating as pay-off reel providing an incoming strip to the rolling gap formed in the mill stand.
  • the other reel is used as a tension reel coiling the outgoing strip after the rolling path. Since single-stand reversing mills are generally known in the art, a detailed description is considered as not necessary in this application.
  • the hot rolled material is then (after cooling down) transferred as a coil to a cold rolling stage 130 arranged downstream of the hot rolling stage in the material flow direction.
  • the cold rolling mill could be a single stand (as shown) or a multiple stands cold mill.
  • a batch furnace 140 is arranged downstream of the cold rolling stage 130 .
  • the batch furnace is configured to receive multiple coils CL after cold rolling and to perform intermediate annealing of the cold material to achieve full recrystallization of the sheet material.
  • a further cold rolling stage 150 is arranged downstream of the intermediate annealing batch furnace 140 to apply cold rolling to the recrystallized material to obtain cold rolled material at the final gauge desired for further processing steps, e.g., as a H1X material or, more specifically, as a H19 material.
  • the cold rolling mill 150 comprises a single stand in the example of FIG. 1 .
  • An exemplary process for producing aluminum can sheet on the installation 100 was performed as follows.
  • an aluminum alloy was cast to form a casting and subsequently scalped to obtain a body of cast and scalped aluminum alloy suitable for further processing.
  • This body is also denoted as ingot in the following.
  • the aluminum alloy can be a can body stock material such as AA3004, AA3104 or other aluminum alloy basically suitable for making aluminum can sheet.
  • the aluminum alloy used in exemplary processes comprised about 0.30 wt % Si, about 0.50 wt % Fe, about 0.95 wt % Mn, about 1.10 wt % Mg, about 0.20 wt % Cu, less than 0.05 wt % Ti, less than 0.10 wt % Zn; and up to 0.15 wt % impurities, preferably each of the impurities with less than 0.05 wt %, with the remainder as Al.
  • the ingot was homogenized at about 500-595° C. with soaking time, e.g., from 5 to 20 hours, followed by ingot cooling down to about 490-530° C.
  • the homogenized ingot (aluminum body) was then transferred to the hot rolling mill without significant intermediate cooling so that hot rolling of the ingot started at about this temperature, i.e., at about 490-530° C.
  • a single stand-reversing mill 120 was utilized as hot rolling mill in this installation setup.
  • the thickness of the material was further reduced with hot rolling on the same single stand-reversing mill 120 , with the difference that the material was coiled after each pass (coiling passes).
  • the number of coiling passes was from 2 to 8.
  • the thickness of the material after the last coiling pass was from about 1.7 mm to about 5 mm.
  • the exit temperature of the material after hot rolling i.e., the hot rolling exit temperature T HREX
  • the hot rolling exit temperature was about 200° C. to about 340° C. and preferably about 220° C. to about 280° C.
  • the reduction of each coiling pass was between 20 and 70%.
  • the hot rolled material was cooled down and then transferred to a cold rolling mill.
  • the cold rolled sheet was then transferred in coiled form to a batch furnace 140 for intermediate annealing.
  • An intermediate annealing step was then applied to the cold rolled sheet.
  • Annealing temperatures and annealing times were selected so that the annealed material was allowed to become fully recrystallized and to develop a strong cube texture.
  • a typical range of annealing temperature is from 280° C. to 450° C. with 1 to 12 hours holding time.
  • the recrystallized annealed sheet was then subject to cold rolling to apply a cold reduction suitable to produce a cold rolled sheet with a final gauge.
  • cold rolling from 70% to 95% reduction was applied to the recrystallizes sheet, giving the material the required strength and balancing the cube texture with rolling texture.
  • the cube texture developed after annealing was weak and the final product had high 45° earing.
  • the un-recrystallized hot band undergoes a relative low cold reduction and then an intermediate annealing is applied to the material to become fully soft.
  • an intermediate annealing thickness reduction with cold rolling without deterioration of the strong cube texture after annealing.
  • tandem hot rolling mill may be used instead of a single stand reversing mill to perform the hot rolling step preceding the cold rolling step.
  • FIG. 2 schematically illustrates the technical connection between the degree of recrystallization of the sheet material after the initial hot rolling step and the amount and type of earring after applying cold reduction to the final gauge.
  • FIG. 3 illustrates the importance of the step of cold reduction prior to the intermediate annealing and the effect on the type and degree of earring after cold reduction to the final gauge.
  • the x-axis represents the degree of cold reduction (in percent) applied after the intermediate annealing.
  • the x-axis represents the amount of cold reduction achieved in the cold rolling mill 150 situated downstream of the intermediate annealing furnace 140 .
  • the y-axis represents the type and amount of earring (in percent).
  • the area above the baseline BL corresponds to 0-90° earring, whereas the area below the baseline BL represents 45° earring.
  • the absolute distance of a data point from the baseline in the y-direction of the diagram represents the amount or strength of the respective earring, meaning that a point on the baseline BL corresponds to a sheet showing no earring at all.
  • the curves of the diagram represent general trends established in a high number of experiments.
  • the schematic box plots BP in FIG. 3 indicate that the trends represented by the lines are considered to be significant.
  • FIG. 2 basically illustrates the importance of the requirement that the hot rolling exit temperature should be selected such that any recrystallization of the hot rolled sheet should be avoided as much as possible.
  • the solid line represents our method where the rolled sheet is substantially un-recrystallized after finishing the hot rolling operation.
  • the lower curve (dashed line) represents reference examples where the sheets were partially recrystallized after finishing the hot rolling step which, in other words, means that the recrystallization was not sufficiently avoided in the presented reference processes.
  • the degree of 0-90° earring is continuously decreased so that shortly before obtaining the final gauge (at the highest point of cold reduction) there is no discernible earring (solid curve crosses the baseline).
  • a certain amount of 45° earring is discernible, but the degree of earring is low in absolute terms.
  • the degree of 0-90° earring is lower than in our methods.
  • the degree of 0-90° earring decreases and would vanish completely at a cold reduction which is not sufficient to obtain the thinner final gauge.
  • the character of the earring changes from 0°-90° earing to predominantly 45° earring and the amount of 45° earring increases to a level much higher in absolute terms than in the material according to the claimed process (solid line). This shows that the degree of recrystallization after the hot rolling step has a significant influence on the amount and character of earring in the final product.
  • the diagram in FIG. 3 can be read in a similar way.
  • the diagram illustrates the importance of the step of cold reduction applied prior to the immediate annealing.
  • the upper curve (dashed line) corresponds to when no cold reduction was applied prior to annealing. This could be a process similar to the processes described in the prior art mentioned in the beginning of this application. It is seen that a high degree of 0°-90° earring is present immediately after the intermediate annealing. When the material is finally cold rolled to the final gauge (maximum amount of cold reduction) there is almost no or very little earring in the final product. If a certain amount of 45° earring is present, the absolute amount is small.
  • the dotted line below the dashed line represents our processes where a cold reduction is applied prior to the intermediate annealing in a cold mill rolling the (essentially un-recrystallized) material exiting the hot rolling state before the material is transferred to the intermediate annealing.
  • the amount of 0-90° earring is less than in no cold reduction prior to annealing.
  • the sheet is reduced in thickness to the final gauge (at maximum cold reduction), there is a significant amount of 45° earring, which is a property desired by many can makers working with a very thin aluminum sheet.
  • This disclosure also relates to a method of making an aluminum can comprising the method steps of the method of producing aluminum can sheet, wherein the cold rolled sheet with the final gauge is formed into a cup-shaped article suitable for making an aluminum can.

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US17/908,974 2020-03-03 2021-03-01 Method and installation for producing aluminum can sheet Pending US20230083429A1 (en)

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US5362341A (en) 1993-01-13 1994-11-08 Aluminum Company Of America Method of producing aluminum can sheet having high strength and low earing characteristics
US5362340A (en) 1993-03-26 1994-11-08 Aluminum Company Of America Method of producing aluminum can sheet having low earing characteristics
US5913989A (en) * 1996-07-08 1999-06-22 Alcan International Limited Process for producing aluminum alloy can body stock
DE19721866B4 (de) 1997-05-16 2006-03-16 Mannesmann Ag Verfahren zur Erzeugung von warmgewalztem Al-Dosenband und Vorrichtung zur Durchführung des Verfahrens
JPH1161365A (ja) * 1997-08-22 1999-03-05 Sky Alum Co Ltd 深絞り用アルミニウム合金板の製造方法
JP3871473B2 (ja) * 1999-07-26 2007-01-24 古河スカイ株式会社 缶胴用アルミニウム合金板の製造方法
JP4011293B2 (ja) * 2001-01-19 2007-11-21 三菱アルミニウム株式会社 耐胴切れ性に優れた缶ボディ用アルミニウム合金板材の製造方法
JP4846457B2 (ja) * 2006-06-06 2011-12-28 古河スカイ株式会社 曲げ加工性に優れたキャップ用アルミニウム合金板の製造方法
CN106103760B (zh) * 2014-03-20 2018-06-05 株式会社Uacj Dr罐体用铝合金板及其制造方法
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
CA3033962C (en) * 2016-08-17 2021-01-26 Novelis Inc. Anodized aluminum with dark gray color
CN106676440B (zh) * 2016-12-22 2018-09-21 新疆众和股份有限公司 一种阳极氧化用硬态铝合金的过程热处理工艺

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EP3875629A1 (en) 2021-09-08
PT3956489T (pt) 2023-10-18
PL3956489T3 (pl) 2024-02-12
MX2022010759A (es) 2022-11-30
ES2963289T3 (es) 2024-03-26
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HRP20231234T1 (hr) 2024-01-19
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