Patent Application
20250154635
This application claims the benefit of Chinese Patent Application No. 202311512951.2 filed on Nov. 14, 2023. The entire disclosure of the application referenced above is incorporated herein by reference.
The information provided in this section is for the purpose of generally presenting the context of the disclosure. Work of the presently named inventors, to the extent it is described in this section, as well as aspects of the description that may not otherwise qualify as prior art at the time of filing, are neither expressly nor impliedly admitted as prior art against the present disclosure.
This disclosure relates to aluminum sheet materials, and in particular to production methods and alloy compositions for reduced energy consumption and CO2 emissions compared with the conventional production of aluminum sheet materials.
Aluminum sheet products used in fabrication of automobiles and other products are typically made from primary aluminum, i.e., aluminum produced directly from mined ore. This is because conventional manufacturing processes are not well-adapted for using secondary aluminum such as aluminum scrap and recycled aluminum. However, the production of aluminum sheet, and the fabrication of parts therefrom, is very energy intensive, and can result in the generation of greenhouse gases, most notably CO2.
Embodiments of this disclosure provide methods of producing aluminum sheet material, and large parts for commercial and consumer products, using appreciable quantities of secondary aluminum with reduced energy usage and emission of CO2 compared with the production of such sheet material and parts from primary aluminum.
Embodiments of this disclosure further provide aluminum sheet material that is manufactured with appreciable quantities of secondary aluminum, reducing energy consumption and emission of CO2, yet is still suitable for the production of large parts for commercial and consumer products, such as automobile parts.
Embodiments of this disclosure further provide an aluminum alloy composition specifically adapted for use in manufacturing processes incorporating aluminum from secondary sources.
According to a first embodiment of this disclosure, a method of manufacturing an aluminum sheet material useful in the production of large parts or commercial and consumer products, such as automobile panels, is provided. Generally, the method comprises the steps of melting secondary aluminum; adding primary aluminum and other alloying elements to the melt to achieve a composition consisting essentially of from 2.5 wt % to 6.3 wt % Mg, from 0.6 wt % to 2.5 wt % Si, from 0.2 wt % to 0.4 wt % Fe, from 0.05 wt % to 0.2 wt % Cr, up to 0.6 wt % Mn, up to 0.2 wt % Cu, up to 0.2 wt % Zn, the balance being Al and unavoidable impurities, wherein the Si and Mg contents satisfy the relationship (Si wt. %>0.5*Mg wt. %-0.65 wt. %); and continuously casting the aluminum alloy into aluminum sheet. The alloy can be continuously cast using either a twin roll continuous caster, or a twin belt continuous caster.
According to a second embodiment of this disclosure, a continuously cast aluminum sheet material is provided. The aluminum sheet has a composition consisting essentially of from 2.5 wt % to 6.3 wt % Mg, from 0.6 wt % to 2.5 wt % Si, from 0.2 wt % to 0.4 wt % Fe, from 0.05 wt % to 0.2 wt % Cr, up to 0.6 wt % Mn, up to 0.2 wt % Cu, up to 0.2. wt % Zn, the balance being Al and unavoidable impurities, wherein the Si and Mg contents satisfy the relationship (Si wt. %>0.5*Mg wt. %-0.65 wt. %). The sheet can be continuously cast using either a twin roll continuous caster, or a twin belt continuous caster.
According to a third embodiment of this disclosure an aluminum alloy adapted for continuous casting is provided. The aluminum alloy can comprise from 2.5 wt % to 6.3 wt % Mg, from 0.6 wt % to 2.5 wt % Si, from 0.2 wt % to 0.4 wt % Fe, from 0.05 wt % to 0.2 wt % Cr, up to 0.6 wt % Mn, up to 0.2 wt % Cu, up to 0.2 wt % Zn, the balance being Al and unavoidable impurities, wherein the Si and Mg contents satisfy the relationship (Si wt. %>0.5*Mg wt. %-0.65 wt. %). The alloy is adapted to be continuously cast using either a twin roll continuous caster, or a twin belt continuous caster.
Further areas of applicability of the present disclosure will become apparent from the detailed description, the claims, and the drawings. The detailed description and specific examples are intended for purposes of illustration only and are not intended to limit the scope of the disclosure.
The present disclosure will become more fully understood from the detailed description and the accompanying drawings, wherein:
In the drawings, reference numbers may be reused to identify similar and/or identical elements.
A first embodiment of this disclosure provides methods of producing aluminum sheet material, and large parts for commercial and consumer products, using appreciable quantities of secondary aluminum with reduced energy usage and emission of CO2 compared with the production of such sheet material and parts from primary aluminum. Although even minimal usage of secondary aluminum can reduce the energy consumption and emission of CO2. Some embodiments of the method can employ at least 30% secondary aluminum from scrap and recycling streams, and more others at least 60% secondary aluminum, and it is possible that embodiments can include up to and even including 100% secondary aluminum.
As shown in
The composition of the melt is determined, and at 104 the composition is adjusted to be within the target range by adding primary aluminum to dilute constituents that are over-represented as compared to the target composition, and alloying elements and master alloys can be added to raise the content of constituents that are under-represented as compared to the target composition. The identity of the scrap and recycling streams and their relative proportions can be selected so that at least 30% of aluminum in the alloy comes from secondary sources, so that the primary aluminum accounts for less than 70% of the aluminum content, such that the resulting energy savings and reduced CO2 justify the effort and cost. In some embodiments, the use of primary aluminum can be reduced to less than 40% of the total aluminum content.
The melted scrap and recycled material is adjusted through the addition of primary aluminum and other alloying constituents to achieve a composition consisting essentially of from 2.5 wt % to 6.3 wt % Mg, from 0.6 wt % to 2.5 wt % Si, from 0.2 wt % to 0.4 wt % Fe, from 0.05 wt % to 0.2 wt % Cr, up to 0.6 wt % Mn, up to 0.2 wt % Cu, up to 0.2 wt % Zn, the balance being Al and unavoidable impurities, wherein the silicon and magnesium contents satisfy the relationship (Si wt. %>0.5*Mg wt. %-0.65 wt. %). As shown in
The inventors have also discovered that it can be beneficial in at least some instances to control the Mn content, which can contribute to the formation of undesirable sludge particles. In instances where these particles could interfere with subsequent forming processes using the alloy sheets to induce unexpected cracks, it can be desirable to keep the Mn content below about 0.6 wt % as illustrated by
Once the alloy composition has been adjusted to the desired composition, at 106 it can then be continuously cast, using either a twin-roller continuous caster, or a twin-belt continuous caster. A twin-belt continuous caster can have a cooling rate as fast as 100° C./s, while a twin-roll continuous caster can have a cooling rate as fast as 1000° C./s. Fast cooling the cooling rates, and relatively low solidification rates help reduce the formation of large precipitates that interfere with the subsequent fabrication of parts from the resulting sheets.
In some embodiments, the target alloy composition can be from 2.5 wt % to 4.5% Mg and from 0.6 wt % to 1.6% Si, which requires a less-tonnage machine for twin-roll/twin-belt processing since high alloying contents will harden the Al alloy in deformation. The composition of the other elements can be from 0.20 wt % to 0.35 wt % Fe, 0.05 wt % to 0.15 wt % Cr, up to 0.4 wt % Mn, up to 0.1 wt % Cu, and up to 0.1 wt % Zn. Smaller amounts of Fe, Mn and Cr can help reduce the volume of brittle intermetallic particles formed. The inventors have discovered that the amount and relative proportion of Mg and Si can affect the solidification range. Through thermodynamic investigations, the inventors have determined that it can be advantageous to have the Si and Mg content satisfy this relation: Si wt. %>0.5*Mg wt. %-0.65 wt. %, and in other embodiments satisfy this relation: Si wt. %>0.5*Mg wt. %-0.35 wt. %).
After initial production of the sheet, it can be subjected to various types of processing to improve its formability. For example, the cast sheet can be subjected to hot rolling the cast sheet, the annealing the hot rolled sheet, the cold rolling the annealed sheet, and the annealing the cold rolled sheet. An alternative process could include homogenization of the cast sheet, cold rolling the homogenized sheet, and annealing the cold rolled sheet.
A second embodiment of this disclosure provides aluminum sheet material that is manufactured with appreciable quantities of secondary aluminum, reducing energy consumption and emission of CO2, yet is still suitable for the production of large parts for commercial and consumer products, such as automobile parts. Although even minimal usage of secondary aluminum can reduce the energy consumption and emission of CO2, in some embodiments the aluminum sheet material contains at least 30% secondary aluminum from scrap and recycling streams, and more in other embodiments at least 60% secondary aluminum, and it is possible that it can include up to and even including 100% secondary aluminum.
According to this second embodiment this aluminum sheet can have a composition consisting essentially of from 2.5 wt % to 6.3 wt % Mg, from 0.6 wt % to 2.5 wt % Si, from 0.2 wt % to 0.4 wt % Fe, from 0.05 wt % to 0.2 wt % Cr, up to 0.6 wt % Mn, up to 0.2 wt % Cu, up to 0.2 wt % Zn, the balance being Al and unavoidable impurities, wherein the silicon and magnesium contents satisfy the relationship (Si wt. %>0.5*Mg wt. %-0.65 wt. %). This composition accommodates various alloying elements introduced from the scrap and recycled streams of material, yet can still be formed into sheet using a continuous casting process. This composition allows an appreciable amount of secondary aluminum (at least 30%), and can easily accommodate 60% or more secondary aluminum to be used depending on the amount and composition of scrap and recycled aluminum available.
In some embodiments, the composition of the sheet is from 2.5 wt % to 4.5% Mg and from 0.6 wt % to 1.6% Si, and from 0.25 wt % to 0.35 wt % Fe, 0.1 wt % to 0.15 wt % Cr, up to 0.4 wt % Mn, up to 0.2 wt % Cu, and up to 0.2 wt % Zn.
The sheet can be continuously cast using either a twin-roller continuous caster, or a twin-belt continuous caster. A twin-belt continuous caster can have a cooling rate as fast as 100° C./s, while a twin-roll continuous caster can have a cooling rate as fast as 1000° C./s. Fast cooling the cooling rates, and relatively low solidification rates help reduce the formation of large precipitates that interfere with the subsequent fabrication of parts from the resulting sheets.
A third embodiment of this disclosure provides an aluminum alloy composition specifically adapted for use in manufacturing processes incorporating aluminum from secondary sources. The composition is tolerant of alloying elements introduced by the scrap and recycled aluminum, and has a low enough solidification range (for example below 100° C. and in some cases below about 85° C. to permit formation using continuous casting technologies such as twin-roll continuous casters or twin-belt continuous casters.
The alloy can have a composition of comprising from 2.5 wt % to 6.3 wt % Mg, from 0.6 wt % to 2.5 wt % Si, from 0.2 wt % to 0.4 wt % Fe, from 0.05 wt % to 0.2 wt % Cr, up to 0.6 wt % Mn, up to 0.2 wt % Cu, up to 0.2 wt % Zn, the balance being Al and unavoidable impurities, wherein the silicon and magnesium contents satisfy the relationship (Si wt. %>0.5*Mg wt. %-0.65 wt. %). In other embodiments the composition can be from 2.5 wt % to 4.5% Mg and from 0.6 wt % to 1.6% Si. The composition can be from 0.20 wt % to 0.30 wt % Fe, 0.05 wt % to 0.15 wt % Cr, up to 0.4 wt % Mn, up to 0.1 wt % Cu, and up to 0.1 wt % Zn.
The inventors have discovered that the amount and relative proportion of Mg and Si can affect the solidification range. Through thermodynamic studies that it can be desirable that the Si and Mg content satisfy this relation: Si wt. %>0.5*Mg wt. %-0.65 wt. %, and more desirably satisfy this relation: Si wt. %>0.5*Mg wt. %-0.35 wt. %). The composition can be selected to have a solidification range of less than 100° C., and in some embodiments less than 85° C. In some embodiments the solidification is selected to be less than or equal to the cooling rate per second of the continuous casting system, and in some embodiments as much as a factor of ten less that the cooling rate per second of the continuous casting system.
Because the alloy is prepared with an appreciable amount of scrap aluminum and recycled aluminum, it may include other elements in quantities that do not substantially impact the relevant properties of the alloy for making quality aluminum sheet for there may be other elements including for example titanium, vanadium, and strontium, without departing from the principles of this disclosure, provided that its solidification range and castability using continuous casting technology, its formability into parts, and the mechanical strength of those parts is not adversely affected.
The alloy will generally have a microstructure consisting of an Al matrix, with fragmented and spherodized Mg2Si particles, and some block-shaped Al—(Cr, Fe, Mn)—Si particles.
The alloy is particularly suited for the production of aluminum sheet using continuous casting methods, and in particular twin-roll and twin-belt continuous casters. These sheets in-turn are adapted for forming parts, for example using hot forming, such as hot stamping, to form deep drawn parts and parts with complex geometries.
The foregoing description is merely illustrative in nature and is in no way intended to limit the disclosure, its application, or uses. The broad teachings of the disclosure can be implemented in a variety of forms. Therefore, while this disclosure includes particular examples, the true scope of the disclosure should not be so limited since other modifications will become apparent upon a study of the drawings, the specification, and the following claims. It should be understood that one or more steps within a method may be executed in different order (or concurrently) without altering the principles of the present disclosure. Further, although each of the embodiments is described above as having certain features, any one or more of those features described with respect to any embodiment of the disclosure can be implemented in and/or combined with features of any of the other embodiments, even if that combination is not explicitly described. In other words, the described embodiments are not mutually exclusive, and permutations of one or more embodiments with one another remain within the scope of this disclosure.
Spatial and functional relationships between elements (for example, between modules, circuit elements, semiconductor layers, etc.) are described using various terms, including “connected,” “engaged,” “coupled,” “adjacent,” “next to,” “on top of,” “above,” “below,” and “disposed.” Unless explicitly described as being “direct,” when a relationship between first and second elements is described in the above disclosure, that relationship can be a direct relationship where no other intervening elements are present between the first and second elements, but can also be an indirect relationship where one or more intervening elements are present (either spatially or functionally) between the first and second elements. As used herein, the phrase at least one of A, B, and C should be construed to mean a logical (A OR B OR C), using a non-exclusive logical OR, and should not be construed to mean “at least one of A, at least one of B, and at least one of C.”
| Number | Date | Country | Kind |
|---|---|---|---|
| 2023115129512 | Nov 2023 | CN | national |
