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US-12618131-B2 - Method of manufacturing an aluminium alloy rolled product

US12618131B2US 12618131 B2US12618131 B2US 12618131B2US-12618131-B2

Abstract

Described herein is a method of manufacturing an aluminium alloy rolled product of a heat-treatable aluminium alloy, comprising: semi-continuous casting a heat-treatable aluminium alloy into a rolling ingot; homogenizing of the rolling ingot to a peak metal temperature (PMT) and whereby said aluminium alloy has a specific energy associated with a DSC signal less than 2J/g in absolute value; hot rolling of the rolling ingot in multiple hot rolling steps into a hot rolled product having a final rolling gauge of at least 1 mm, whereby the hot rolled product during at least one of the last three rolling steps has a temperature less than 50° C. below PMT; quenching of the hot rolled product at final rolling gauge from hot-mill exit temperature to below 175° C.; optionally stress relieving and ageing of the quenched and optionally stress relieved hot rolled product.

Inventors

  • Philippe Meyer

Assignees

  • NOVELIS KOBLENZ GMBH

Dates

Publication Date
20260505
Application Date
20201218
Priority Date
20191223

Claims (15)

  1. 1 . A method of manufacturing an aluminium alloy rolled product of a heat-treatable aluminium alloy having a thickness of at least 1 mm, comprising the steps of: (a) semi-continuous casting a heat-treatable aluminium alloy into a rolling ingot having a thickness of at least 250 mm; (b) preheating and/or homogenizing of the rolling ingot to a peak metal temperature (PMT) of less than 530°° C., wherein after said preheating and/or homogenizing the rolling ingot exhibits a specific energy associated with a Differential Scanning Calorimetry (DSC) signal less than 2 J/g in absolute value; (c) hot rolling of the rolling ingot in multiple hot rolling steps into a hot rolled product having a final rolling gauge of at least 10 mm, wherein hot rolling occurs in at least three hot rolling steps whereby the hot rolled product during at least one of the last three rolling steps has a temperature less than 50° C. below PMT (° C.); (d) quenching of the hot rolled product at final rolling gauge from hot-mill exit temperature to below 175° C.; (e) optionally stress relieving of the quenched and hot rolled product at final rolling gauge; and (f) ageing of the quenched and optionally stress relieved hot rolled product.
  2. 2 . The method according to claim 1 , wherein the method is free from any solution heat-treatment following the hot rolling to a final hot rolling gauge of step (c).
  3. 3 . The method according to claim 1 , wherein the quenching during step (d) is performed in-line with at least the last hot rolling step.
  4. 4 . The method according to claim 1 , wherein the aluminium alloy is selected from the group of 2XXX-, 6XXX, and 7XXX-series aluminium alloys.
  5. 5 . The method according to claim 1 , wherein after said preheating and/or homogenizing, the rolling ingot exhibits a specific energy associated with a DSC signal less than 1.0 J/g in absolute value.
  6. 6 . The method according to claim 1 , wherein for 2XXX-series aluminum alloy products the PMT for preheating and/or homogenizing is at a temperature of from 430° C. to 505° C., and wherein for 7XXX-series aluminium alloy products the PMT for preheating and/or homogenizing is at a temperature of from 430° C. to 490° C.
  7. 7 . The method according to claim 1 , wherein the hot-mill entry temperature is less than 40° C. below the PMT of the aluminium alloy.
  8. 8 . The method according to claim 1 , wherein the hot-mill exit temperature of the hot rolled product at final rolling gauge is less than 40° C. below the PMT of the aluminium alloy.
  9. 9 . The method according to claim 1 , wherein step (e) is performed and wherein during step (e) the stress relieving is by stretching in a range of 0.5% to 8% of its original length.
  10. 10 . The method according to claim 1 , wherein the hot rolled product at final hot rolling gauge is 25.4 mm or more.
  11. 11 . The method according to claim 1 , wherein during step (c) the rolling ingot is hot rolled in a first series of hot rolling steps to an intermediate hot rolled gauge, followed by an intermediate heating step and then in a second series of hot rolling steps hot rolled to final hot rolled gauge of at least 10 mm.
  12. 12 . The method according to claim 11 , wherein the intermediate heating step is to less than 40° C. below the PMT of the aluminium alloy.
  13. 13 . The method according to claim 1 , wherein the aluminium alloy is a 2XXX-series aluminium alloy having composition comprising, in wt. %: Cu 1.9% to 7%, Mg 0.3% to 2%, Mn up to 1.2%, Si up to 0.4%, Fe up to 0.4%, Cr up to 0.35%, Zn up to 0.4%, Ti up to 0.15%, Zr up to 0.25, V up to 0.25%, balance being aluminium and impurities.
  14. 14 . The method according to claim 1 , wherein the aluminium alloy is a 6XXX-series aluminium alloy having a composition comprising, in wt. %: Si 0.2% to 1.7%, Mg 0.1% to 1.5%, Fe up to 0.5%, Cu up to 1.0%, Mn up to 1.0%, Cr up to 0.3%, Ti up to 0.15%, Zn up to 1.0%, balance being aluminium and impurities.
  15. 15 . The method according to claim 1 , wherein the aluminium alloy is a 7XXX-series aluminium alloy having a composition comprising, in wt. %: Zn 4% to 9.8%, Mg 1% to 3%, Cu up to 2.5%, and optionally one or more elements selected from the group consisting of: Zr up to 0.3%, Cr up to 0.3%, Mn up to 0.45%, Ti up to 0.15%, Sc up to 0.5%, and Ag up to 0.5%, Fe up to 0.3%, Si up to 0.3%, balance being aluminum and impurities.

Description

CROSS REFERENCE TO RELATED APPLICATION This application claims the benefit of and priority to European Patent Application No. 19219448.8, filed Dec. 23, 2019 and titled “Method of Manufacturing an Aluminium Alloy Rolled Product,” the content of which is herein incorporated by reference in its entirety. FIELD Described herein is a method of manufacturing an aluminium alloy sheet, shate or plate product, such as a heat-treatable aluminium alloy. The aluminium alloy sheet, shate or plate product can be used in a wide variety of applications, for example, as tooling plate or shate and armour plate. BACKGROUND On an industrial scale, the process or method of manufacturing aluminium alloy rolled sheet, shate and plate products, in particular of heat-treatable aluminium alloys of the 2XXX-, 6XXX- and 7XXX-series aluminium alloys, comprises the process steps of, in that order: (i). casting of a rolling ingot of the aluminium alloy, and preferably after degassing and filtering of the molten aluminium prior to casting;(ii). preheating and/or homogenizing of the rolling ingot;(iii). hot rolling of the ingot into a rolled product at intermediate rolling gauge or final rolling gauge and coiled or cut-to-length and cooled to ambient temperature;(iv). optionally cold working, e.g., cold rolling, of the hot rolled product to final rolling gauge;(v). heating from ambient temperature to a target solution heat treatment temperature for solution heat treating (“SHT”) of the rolled product to bring as much as possible all or substantially all portions of the soluble elements like zinc, magnesium, manganese and copper into solid solution;(vi). rapid cooling the SHT rolled product, for example by one of spray quenching or immersion quenching in water or other suitable quenching media to a temperature of 175° C. or lower, and preferably to ambient temperature, to prevent or minimize the uncontrolled precipitation of secondary phases in the aluminium alloy; further, air and air jets may be employed;(vii). optionally stretching or compressing of the SHT and cooled product to relieve stresses and to improve product flatness; and(viii). ageing, i.e., natural ageing or artificial ageing or a combination thereof, of the rolled product, for example to a T3, T4, T6, T7 or T8 condition depending on the heat-treatable aluminium alloy and condition desired. The resultant rolled products are of high quality and can be used amongst others for aerospace applications, but also as armour plate and tooling plate. Each process step requires its own expensive hardware and support tooling and the aluminium alloy products require a lot of handling before and after each process step leading to complex logistical systems in an industrial environment. An alternative method of making aluminium plate products is by using so-called cast plates. These cast plates are suitable as tooling plate, e.g., for making semi-conductor related devices and for mechanical parts. Such a method, for example, includes the steps of, in that order, melting of an aluminium alloy, degassing and filtering of the molten aluminium prior to casting, casting to produce a slab, and a slicing step for slicing the slab into a predetermined thickness, and preferably a surface smoothening process step. The method comprises preferably a heat treatment step for homogenization performed after the casting step and prior to the slicing step. The aluminium alloys are not subjected to any thermo-mechanical deformation process such as hot rolling. A disadvantage of cast plate is that the unavoidable phases resulting from the combination and precipitation at grain boundaries of elements like iron, manganese, copper, zinc, magnesium, and silicon, often in an eutectic form after solidification, cannot be fully dissolved in the subsequent processing steps like homogenization and SHT and remain as sites for crack initiation, thus lowering the mechanical properties (e.g., ultimate tensile strength, fatigue, elongation, toughness, and others), or as initiators of local corrosion (e.g. pitting corrosion) and may be harmful also for final treatments like anodization. Any oxide layer present in the cast alloy will also remain in its original shape therefore also lowering the mechanical properties. Because substantially the as-cast microstructure is maintained, and strongly depends on the local cooling speed, there is much more variation in mechanical properties as function of the testing location as compared to rolled plate products, rendering cast plates unsuitable for many critical engineering applications. Existing methods in the art outline that aluminium alloy rolling ingots require a metallurgical homogenization heat treatment before hot rolling. The difference between the homogenization temperature and the hot rolling temperature is between 30° C. and 150° C., depending on the alloys. The ingot must therefore be cooled between leaving the homogenization furnace and the beginning of hot rolling. The