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
• • 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
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B15/00—Layered products comprising a layer of metal
  • B32B15/01—Layered products comprising a layer of metal all layers being exclusively metallic
  • B32B15/016—Layered products comprising a layer of metal all layers being exclusively metallic all layers being formed of aluminium or aluminium alloys
• • 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
  • C22C21/08—Alloys based on aluminium with magnesium as the next major constituent with silicon
• • 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
  • C22C21/12—Alloys based on aluminium 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
• • 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
  • 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
  • C22F1/05—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 of the Al-Si-Mg type, i.e. containing silicon and magnesium in approximately equal proportions
• • 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
  • C22F1/053—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 zinc as the next major constituent
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T428/00—Stock material or miscellaneous articles
  • Y10T428/12—All metal or with adjacent metals
  • Y10T428/12493—Composite; i.e., plural, adjacent, spatially distinct metal components [e.g., layers, joint, etc.]
  • Y10T428/12736—Al-base component
  • Y10T428/12764—Next to Al-base component

Definitions

• This invention relates to improvements in sheets of aluminium alloy and methods of manufacturing same.
• the invention is concerned particularly with methods of producing aluminium alloysheet materials intended to withstand high temperatures.
• Aluminium alloy sheet which is used, for example, for the skins of aircraft intended to fly at supersonic speeds requires to have a high level of static tensile strength after thousands of hours at the service temperatures to which such skins are exposed and good creep resistance and fatigue strength at the same temperatures.
• the sheets may be used in the unclad form or may be clad on one or both main faces with a layer of commercially pure aluminium or aluminium containing from about 0.8 to 1.2 percent by weight of zinc or with a layer of heat-treatable corrosion-resistant aluminium base alloy containing a similaramount of zinc.
• the thickness of each cladding layer is usually between 3 and 7 percent of the total thickness of the clad sheet.
• Suitable alloys for heat-treatable corrosion-resistant claddings of the kind mentioned are the well known aluminium-magriesium-silicon type series of alloys (hereinafter referred to as the series hereinbefore defined) the compositions of which, by weight, fall within the range 0.4 to 1.4 percent magnesium, 0.2 to 1.3 percent silicon, 0.0 to 1.0 percent manganese, 0.0 to 0.3 percent chromium, the remainder being aluminium together with the normal amounts of impurities and grain refining elements found in such alloys, except that in the make-up of any of these alloys there is included an addition of between about 0.8 and 1.2 percent byweight of zinc.
• the series hereinbefore defined the compositions of which, by weight, fall within the range 0.4 to 1.4 percent magnesium, 0.2 to 1.3 percent silicon, 0.0 to 1.0 percent manganese, 0.0 to 0.3 percent chromium, the remainder being aluminium together with the normal amounts of impurities and grain refining elements found in such alloys, except that in the make-up of
• the preferred alloy foruse as cladding is that according to British Standards Specification 1470:HS.30 with an addition of between 0.8 and 1.2 percent by weight of zinc. It is well known that the creep resistance of aluminiu alloys is effected by the grain-size of the material, the coarser the grain the better being the creep resistance. On the other hand, too coarse a grain is undesirable in sheet materials if the latter are to be formed by bending, stretching or drawing, because under these conditions the resulting product may suffer from the deleterious effect visible on the formed surfaces and known as orange peeling. In the forged condition aluminium alloys can be produced with a controlled coarse grain-size which enhances the creep resisting properties and there is no difficulty associated with this grain-size because forgings are not normally formed after manufacture.
• aluminium alloy sheet from recrystallised hot rolled slab by imposing heavy' cold rolling reductions of the order of to percent or more, between inter-stage recrystallising anneals, and finishing to the required thickness with-a final cold rolling reduction of the same order of magnitude. After solution heat-treatment, the resulting sheet has a relatively fine grain-size which ensures ease of formability.
• the principal factors affecting the ultimate grain-size in sheet are the degree of reduction in the-final cold rolling and the time and the temperature of the subsequent heat treatment. There is a critical range between about 1.5 percent and 11 percent in the reduction during final cold rolling which produces large grains on subsequent solution heat-treatment.
• the preferred temperature not substantially less than 12% and not substantially more than 50%, a recrystallising anneal being given after each reduction except the last, the cold-rolled sheet is subjected to solution heat-treatment for not substantially less than 15 minutes and not substantially more than 50 minutes at a temperature not substantially less than 525 C. and not substantially more than 545 C. and the sheet is then quenched and artificially aged.
• the solution heat-treatment temperature for a time which depends on the thickness and weight of the slabs and may be from about to about 48 hours. After this treatment, the slabs may be allowed to cool to the required temperature and hot-rolled immediately, or cooled down to room-temperature and subsequently heated to the required temperature prior to hot-rolling.
• the conditions which we have found satisfactory for the recovery annealing treatment are between minutes and 3 hours at a selected temperature between 150 and 300 0, although a similar unexpected improvement has been observed in the creep resistance of sheet material stored at room temperature for several months after final cold rolling and prior to solution heat-treatment and artificial ageing.
• the aluminium alloy which we use is compounded of the following elements in the following proportions by weight:
• a or more of the elements barium, calcium and strontium may be present in a total amount of not more than 0.2 percent.
• One or more of the following elements may be present up to a maximum amount of 0.1 percent total: tin, arsenic, bismuth, cadmium, boron, lithium, sodium and potassium. Aluminium the remainder.
• This alloy is hereinafter referred to in this specification and in the claims as an aluminium alloy having a composition as hereinbefore defined.
• Aluminium core alloys of the same general nature as that defined above are normally cast by the semi-continuous or continuous casting process and it is desirable that the alloys which we use should be cast by one of said processes.
• Sheet can be produced by the method according to this invention with an average intercept diameter of the grains in the core of between 0.0399 millimeter, which is equivalent to A.S.T.M. No. 6.0 determined by-the standard A.S.T.M. method of estimating the average grain-size of metals, and 0.0168 millimetre, which is equivalent to A.S.T.M. No. 8.5.
• the method used for determining the A.S.T.M. numbers for the average grain-size is that described for the comparison procedure in the American Society for Testing and Materials Standard Designation: E.1l2-61.
• the sheets are formable without the production of the orange peeling effect andtheir creep resist ance is very much better than that of sheets processed in the normal way.
• Example 1 In the following seven clad sheets A to G, inclusive, the composition of all the aluminium alloy cores was within the limits:
• melts were made up to the above composition and cast into rolling slabs which were .not homogenised but were processed and clad with cladding sheets in the normal way by hot rolling down to an appropriate thickness.
• the cladding was on both main faces of thesheet and each layer was a nominal 5 percent of the total thickness of each sheet.
• the cladding used for sheets A, B, C and D was compounded of commercially pure aluminium and from 0.8 to 1.2 percent of zinc by weight.
• the cladding was a heat-treatable corrosion resistant alloy made from commercially pure aluminium and about 0.7 percent of magnesium, 1.0 percent of silicon, 0.55 percent of manganese with an addition of about 1.0 percent of zinc, all by weight, together with the normal impurities present in such alloys. Apart from the Zinc addition, this latter alloy conformed to the compositional requirements of the British Standards Specification 1470: HS.30.
• the sheets were then subjected to cold rolling reductions.
• All the sheets were finally artifically aged for 20 to 24 hours at 190 C. in a forced'air circulation furnace.
• Suitable specimens were cut from the heat-treated sheets and prepared and assessed for grain-size of the core material by the method described for the comparison procedure in A.S.T.M. Standard: E. 112-61, and the results are shown in Table 1. Specimens were also prepared in a direction transverse to the direction of final rolling for testing under standard tensile creep test conditions in accordance with British Standards Specification 3500: Part 3: 1962, at C. under a stress of 12 tons per square inch. The percentage total plastic creep strains, after 500 hours, for this series of tests are also shown in Table 1. I
• sheets F and Sheet Id ntifi ati J K G made according to the present invention and clad wlthuthe heat'treatabllf 'l' f Zn claddmg, have 1 1' Perli'centageulnter-stage 1Cold Reductions Prior to Last 4 4 srna grain-size and t eir CIC6p'I6SlSlIaI1C6S are very muc ecrysta 18mg Annea 2 2 P t 1 d A L R 11 superior to that of the correspondlng sheet E made Kitflfi Cod Re ucmn ecrysta 24 24 3 Thickness of SheetinInches 0. 064 0.064 accordmg l f t standard procedure but outslde th A.S.T.M. Grain-Size Number After Full Heat Treatscope of this inventlon. ment 7. 0 6.5
• Example 3 The effects of prior homogenisation of the cast rolling slabs, with and without subsequent recovery annealing of the finally cold rolled sheet, are shown by the following example I
• a cast rolling slab was made up according to the composition given in Example 1 and homogenised for 20 hours at 520 C. before hot rolling and cladding, as in sheets A to D inclusive, on both main faces with a layer equal to about 5 percent of the total thickness of the sheet, with an alloy compounded of commercially pure aluminium and nominally 1 percent of zinc by weight.
• the hot-rolled slab was cold rolled in substantially the same way as for sheet C in Exampe 1.
• One portion of the resulting sheet was not recovery annealed after the final cold rolling operation and this was designated sheet I.
• a second portion was rec'overy annealed for 2 hours at 285 C. after the final cold rolling and this was designated sheet K.
• Suitable specimens were cutfrom both sheets I and p K and solution heat-treated and artificially aged at the same temperatures and for the same times as used in Example 2. The specimens were then tested for grainsize and tensile creep tested under a load of 12 tons per square inch at 150 C. for 500 hours. The results of these tests are shown in Table 2.
• a method of manufacturing aluminium alloy sheet comprising the steps of forming a slab suit-able for coldrolling into a sheet of an alloy consisting essentially of 2.2 to 2.7 percent by weight copper, 1.3 to !1.7 percent by weight magnesium, 0.12 to 0.25 percent by weight silicon, 0.9 to 1.2 percent by weight iron, 0.9 to 1.4 percent by weight nickel, 0.02 to 0.15 percent by weight titanium and the remainder aluminium, subjecting said slab to a plurality of cold rolling reductions each of which is not substantially less than 12% and not substantially more than 50%, subjecting the cold-rolled sheet to solution heat-treatment for not substantially less than 15 minutes and not substantially more than 50 minutes at a temperature not substantially less than 525 C. and not substantially more than 545 C., and quenching and then artificially ageing the sheet.
• eachof the cold-rolling reductions is between 14 and 45%.
• a method according to claim 1 wherein the artificial ageing is elfected ataa temperature not substantially less than C. and not substantially more than 210 C. for not substantially less than 4 hours and not substantially more than 30 hours.
• a method of manufacturing aluminium alloy sheet comprising the steps of forming a slab suitable for coldrolling into a sheet of an alloy consisting essentially of 2.2 to 2.7 percent by weight copper, 1.3 to 1.7 percent by weight magnesium, 0.12 to 0.25 percent by weight silicon, 0.9 to 1.2 percent by Weight iron, 0.9 to 1.4 percent by weight nickel, 0.02 to 0. 15 percent by weight titanium and the remainder aluminium, subjecting said slab to a plurality of cold rolling reductions each of which is not substantially less than 12% and not substantially more than 50%, subjecting the cold-rolled sheet to recovery annealing for not substantially less than 15 minutes and not substantially more, than 3 hours at a temperature not substantially less than 150 C.
• a method of manufacturing clad aluminium alloy sheet comprising the steps of forming a hot-rolled slab of an alloy consisting essentially of 2.2 to 2.7 percent by Weight copper, 1.3 to 1.7 percent by weight magnesium, 0.12 to 0.25 percent by weight silicon, 0.9 to 1.2 percent by weight iron, 0.9 to 1.4 percent by weight nickel, 0.02 to 0.15 percent by weight titanium and the remainder aluminium, and having cladding of material selected from the group consisting of commercially pure aluminium, aluminium containing not substantially less than 0.8 and not substantially more than 1.2 percent by weight of zinc, and a heat-treatable corrosion-resistant aluminium base alloy consisting essentially of 0.4 to 1.4 percent by weight magnesium, 0.2 to 1.3 percent by weight silicon, 0.0 to 1.0 percent by weight manganese, 0.0 to 0.3 percent by weight chromium, about 0.8 to about 1.2 percent by weight zinc and the remainder aluminium, subjecting said slab to a plurality of cold rolling reductions each of which is not substantially less than 12% and not substantially more than 50%, subject
• a method of manufacturing aluminium alloy sheet comprising the steps of forming a hot-rolled slab of an alloy consisting essentially of 2.2 to 2.7 percent by weight copper, 1.3 to 1.7 percent by weight magnesium, 0.12 to 025 percent by weight silicon, 0.9 to 1.2 percent by weight ir-on, 0.9 to 1.4 percent by weight nickel, 0.02 to 0.15 percent by weight titanium and the remainder aluminium, subjecting said slab to a plurality of cold rolling reductions each of which is not substantially less than 12% and not substantially more than 50%, a recrystallising anneal being given after each reduction except the last, subjecting the cold-rolled sheet to solution heattreatment for not substantially less than 15 minutes and not'substantially more than 50 minutes at a temperature not substantially less than 525 C. and not substantially more than 545 C., and quenching and then artificially ageing the sheet, said cold-rolling and solution heattreatment resulting in anaverage intercept grain diameter in the final sheet of between 0.0399 millimetre and 0.0168 millimetre.
• Aluminium sheet produced by the steps of forming a slab suitable for cold-rolling into a sheet of an alloy consisting essentially of 2.2 to 2.7 percent by weight copper, 1.3 to 1.7 percent by weight magnesium, 0.12 to 0.25 percent by weight silicon, 0.9 to 1.2 percent by weight iron, 0.9 to 1.4 percent by weight nickel, 0.02 to 0. 15 percent by weight titanium and the remainder aluminium, subjecting said slab to a plurality of cold rolling reductions each of which is not substantially less than 12% and not substantially more than 50%, subjecting the cold-rolled sheet to solution heat-treatment for not substantially less than 15 minutes and not substantially more than 50 minutes at a temperature not substantially less 8 than 525 C. and not substantially more than 545 C., and quenching and then artificially ageing the sheet.
• Clad aluminium sheet produced by the steps of forming a hot-rolled slab of an alloy consisting essentially of 2.2 to 2.7 percent by'weight copper, 1.3 to 1.7 percent by weight magnesium, 0.12 to 0.25 percent by weight silicon, 0.9 to 1.2 percent by weight iron, 0.9 to 1.4 percent by weight nickel, 0.02 to 0.15 percent by weight titanium and the remainder aluminium, and having cladding of material selected from the group consisting of commercially pure aluminium, aluminium containing not substantially less than 0.8 and not substantially more than 1.2 percent by weight of zinc, and a heat-treatable corrosion-resistant aluminium base alloy consisting essentially of 0.4 to 1.4 percent by weight magnesium, 0.2 to 1.3 percent by Weight silicon, 0.0 to 1.0 percent by weight manganese, 0.0 to 0.3 percent by weight chromium, about 0.8 to about 1.2 percent by weight zinc and the remainder aluminium, subjecting said slab to a plurality of cold rolling reductions each of which is not substantially less than 12% and not substantially more than 50%, subjecting the cold-rolled
• said alloy includes a minor amount of at least one other element selected from the group consisting of antimony, beryllium, cerium, chromium, cobalt, manganese, molybdenum, niobium, silver, vanadium, zirconium and zinc, the amount of each said element selected being not more than 0.3 percent by weight, the total amount of all said selected elements being not more than 1.0 percent by weight.
• said alloy includes a minor amount of at least one other element selected from the group consisting of antimony, beryllium, cerium, chromium, cobalt, manganese, molybdenum, niobium, vanadium, zirconium and zinc, the amount of each said element selected being not more than 0.3 percent by weight, and silver in an amount greater than 0.3 percent by weight and not more than 0.5 percent by weight, the total amount by weight of all said selected elements and silver being not more than 1.0 percent plus the amount by which the silver exceeds 0.3 percent.
• said alloy includes a minor amount of at least one other element selected from the group consisting of antimony, beryllium, cerium, chromium, cobalt, manganese, molybdenum, niobium, vanadium, zirconium and zinc, the amount of each saidelement selected being not more than 0.3 percent by weight, and silver in an amount gr'eater'than 0.5 percent by weight and not more than 0.8 percent by Weight, the amount of copper being at least as much below 2.5 percent as the amount of silver exceeds 0.5 percent, the total amount by weight of all said selected elements and silver being not more than 1.0 percent plus the amount by which the silver exceeds 0.3 percent.

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• Chemical & Material Sciences (AREA)
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• Mechanical Engineering (AREA)
• Materials Engineering (AREA)
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• Physics & Mathematics (AREA)
• Thermal Sciences (AREA)
• Crystallography & Structural Chemistry (AREA)
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• Pressure Welding/Diffusion-Bonding (AREA)
• Laminated Bodies (AREA)

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Cited By (12)

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Citations (2)

• 0
  • BE BE653836D patent/BE653836A/xx unknown
• 1963
  • 1963-10-02 GB GB38861/63A patent/GB1069982A/en not_active Expired
• 1964
  • 1964-09-28 US US399830A patent/US3310389A/en not_active Expired - Lifetime
  • 1964-09-29 DE DEH53895A patent/DE1284095B/de active Pending
  • 1964-09-29 CH CH1266964A patent/CH468472A/de unknown
  • 1964-10-01 SE SE11826/64A patent/SE328709B/xx unknown
  • 1964-10-02 NL NL6411544A patent/NL6411544A/xx unknown

Patent Citations (2)

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