Method for reducing target surface features in continuous casting
11548062 · 2023-01-10
Assignee
Inventors
Cpc classification
B22D11/0605
PERFORMING OPERATIONS; TRANSPORTING
B22D11/0622
PERFORMING OPERATIONS; TRANSPORTING
International classification
Abstract
A method for reducing target surface features in continuously cast articles is described. The method can remove a target surface feature, such as a compositional variation or casting defect, from the continuously cast article by removing, before cold rolling, material from the continuously cast article surface.
Claims
1. A method, comprising: continuously casting an aluminum alloy to form a continuously cast aluminum alloy article having a first target surface feature on a first surface of the continuously cast aluminum alloy article, wherein the continuously cast aluminum alloy article is a strip or a sheet; and before cold rolling, removing no more than 2,000 μm of material from the first surface of the continuously cast aluminum alloy article to provide a treated article, wherein a dimension of the first target surface feature on the first surface of the treated article is less than a corresponding dimension of the first target surface feature on the first surface of the continuously cast aluminum alloy article, wherein a thickness is reduced by sawing, and wherein the continuously cast aluminum alloy article has a temperature of at least about 400 degrees Fahrenheit during the removing.
2. The method of claim 1, wherein, during the removing of the material from the first surface, the continuously cast aluminum alloy article has a temperature of at least about 700 degrees Fahrenheit, wherein the continuously cast aluminum alloy article comprises primarily aluminum, wherein the continuously cast aluminum alloy article is continuously cast by one or more of a rotary caster, a twin-roll caster, a block caster, a twin-belt caster, and a single roll caster, and wherein the first target surface feature is removed from the first surface in the removing of the material from the first surface.
3. The method of claim 1, wherein the first target surface feature is a compositional deviation, wherein the aluminum alloy of the continuously cast aluminum alloy article is selected from the group consisting of aluminum alloys 1XXX, 2XXX, 3XXX, 4XXX, 5XXX, 6XXX, 7XXX, 8XXX, and 9XXX, wherein, in the removing of the material from the first surface, at least about 10 microns of material is removed from the first surface, and wherein at least 75% of the first target surface feature is removed from the first surface during the removing of the material from the first surface.
4. The method of claim 2, wherein the first target surface feature is one or more of a step, ramp, bow, buckle, streak, drag mark, and block joint, wherein at least 75% of the first target surface feature is removed from the first surface during the removing of the material from the first surface, wherein, in the removing of the material from the first surface, at least about 50 microns of material is removed from the first surface, and wherein the removing of the material from the first surface is performed before hot rolling.
5. The method of claim 1, wherein the first target surface feature comprises an oxidized surface, wherein, during the removing of the material from the first surface, the continuously cast aluminum alloy article has a temperature of at least about 500 degrees Fahrenheit, wherein at least 75% of the first target surface feature is removed from the first surface during the removing of the material from the first surface, and wherein the removing of the material from the first surface is performed between hot rolling stands.
6. The method of claim 1, wherein at least about 50 microns of the material is removed from the first surface, wherein at least 75% of the first target surface feature is removed from the first surface during the removing of the material from the first surface, and wherein the removing of the material from the first surface is performed after hot rolling is completed.
7. The method of claim 6, wherein the aluminum alloy of the continuously cast aluminum alloy article is selected from the group consisting of aluminum alloys 1XXX, 2XXX, 3XXX, 4XXX, 5XXX, 6XXX, 7XXX, 8XXX, and 9XXX, and wherein, during the removing of the material from the first surface, the continuously cast aluminum alloy article has a temperature of at least about 500 degrees Fahrenheit.
8. The method of claim 1, wherein the aluminum alloy of the continuously cast aluminum alloy article is selected from the group consisting of aluminum alloys 1XXX, 2XXX, 3XXX, 4XXX, 5XXX, 6XXX, 7XXX, 8XXX, and 9XXX, and wherein at least about 25% of the first target surface feature is removed during the removing of the material from the first surface.
9. A method, comprising: continuously casting an aluminum alloy to form a continuously cast strip having a target surface feature on a first surface of the continuously cast strip; after casting and before hot rolling, reducing a thickness of the target surface feature while maintaining a constant width of the continuously cast strip derived therefrom to provide a treated strip, wherein the target surface feature is removed from the first surface during the reducing of the thickness of the target surface feature, and wherein the thickness is reduced by one or more of chemically etching, plasma etching, and laser etching, wherein the continuously cast strip has a temperature of at least about 500 degrees Fahrenheit during the removing of the target surface feature; and rolling the treated strip, wherein the rolling comprises hot rolling.
10. The method of claim 9, wherein, during the reducing of the thickness of the target surface feature, the continuously cast strip has a temperature of at least about 700 degrees Fahrenheit, wherein the continuously cast strip comprises primarily aluminum, wherein the continuously cast strip is continuously cast by one or more of a rotary caster, a twin-roll caster, a block caster, a twin-belt caster, and a single roll caster, and wherein the target surface feature is removed from the first surface by removing material from the first surface.
11. The method of claim 9, wherein the target surface feature is a compositional variation, wherein the continuously cast strip is an aluminum alloy selected from the group consisting of aluminum alloys 1XXX, 2XXX, 3XXX, 4XXX, 5XXX, 6XXX, 7XXX, 8XXX, and 9XXX, wherein at least about 10 microns of material is removed from the first surface, and wherein at least 75% of the target surface feature is removed from the first surface during the reducing of the thickness of the target surface feature.
12. The method of claim 10, wherein the target surface feature is one or more of a step, ramp, bow, buckle, streak, drag mark, and block joint, wherein at least 75% of the target surface feature is removed from the first surface during the reducing of the thickness of the target surface feature, and wherein, in the reducing of the thickness of the target surface feature, at least about 50 microns of material is removed from the first surface.
13. The method of claim 9, wherein the target surface feature comprises an oxidized surface, wherein, during the reducing of the thickness of the target surface feature, the continuously cast strip has a temperature of at least about 700 degrees Fahrenheit, and wherein at least 75% of the target surface feature is removed from the first surface during the reducing of the thickness of the target surface feature.
14. The method of claim 9, wherein, in the reducing of the thickness of the target surface feature, at least about 50 microns of material is removed from the first surface, and wherein at least 75% of the target surface feature is removed from the first surface during the reducing of the thickness of the target surface feature.
15. The method of claim 14, wherein the aluminum alloy is selected from the group consisting of aluminum alloys 1XXX, 2XXX, 3XXX, 4XXX, 5XXX, 6XXX, 7XXX, 8XXX, and 9XXX, and wherein, during the reducing of the thickness of the target surface feature, the continuously cast strip has a temperature of at least about 700 degrees Fahrenheit.
16. The method of claim 9, wherein the thickness is reduced by chemically etching, wherein the aluminum alloy is selected from the group consisting of aluminum alloys 1XXX, 2XXX, 3XXX, 4XXX, 5XXX, 6XXX, 7XXX, 8XXX, and 9XXX, and wherein at least about 25% of the target surface feature is removed during the reducing of the thickness of the target surface feature.
17. A method, comprising: continuously casting an aluminum alloy to form a continuously cast aluminum alloy article having a first target surface feature on a first surface of the continuously cast aluminum alloy article, wherein the continuously cast aluminum alloy article is a strip or a sheet; before cold rolling, removing, by one or more of chemical etching, plasma etching, and laser etching, material from the first surface to form a treated article, wherein the continuously cast aluminum alloy article has a temperature of at least about 400 degrees Fahrenheit during the removing; and rolling the treated article, wherein the rolling comprises cold rolling.
18. The method of claim 17, wherein the first target surface feature is removed from the first surface during the removing of the material, by one or more of chemical etching, plasma etching, and laser etching, of the material from the first surface, wherein, during the removing of the material, by one or more of chemical etching, plasma etching, and laser etching, of the material from the first surface, the continuously cast aluminum alloy article has a temperature of at least about 700 degrees Fahrenheit, wherein the continuously cast aluminum alloy article is the strip, wherein the continuously cast aluminum alloy article comprises primarily aluminum, and wherein the continuously cast aluminum alloy article is continuously cast by one or more of a rotary caster, a twin-roll caster, a block caster, a twin-belt caster, and a single roll caster.
19. The method of claim 17, wherein the first target surface feature is a compositional deviation, wherein the aluminum alloy of the continuously cast aluminum alloy article is selected from the group consisting of aluminum alloys 1XXX, 2XXX, 3XXX, 4XXX, 5XXX, 6XXX, 7XXX, 8XXX, and 9XXX, wherein, in the removing of the material from the first surface, at least about 10 microns of material is removed from the first surface, and wherein at least 75% of the first target surface feature is removed from the first surface during the removing.
20. The method of claim 18, wherein the first target surface feature is one or more of a step, ramp, bow, buckle, streak, drag mark, and block joint, wherein at least 75% of the first target surface feature is removed from the first surface during the removing of the material, by one or more of chemical etching, plasma etching, and laser etching, of the material from the first surface, wherein, in the removing of the material, by one or more of chemical etching, plasma etching, and laser etching, of the material from the first surface, at least about 50 microns of material is removed from the first surface, and wherein the removing is performed before hot rolling.
21. The method of claim 17, wherein, during the removing of the material, by one or more of chemical etching, plasma etching, and laser etching, of the material from the first surface, the continuously cast aluminum alloy article has a temperature of at least about 700 degrees Fahrenheit, wherein at least 75% of the first target surface feature is removed from the first surface during the removing of the material, by one or more of chemical etching, plasma etching, and laser etching, of the material from the first surface, and wherein the removing is performed between hot rolling stands.
22. The method of claim 17, wherein, in the removing of the material, by one or more of chemical etching, plasma etching, and laser etching, of the material from the first surface, at least about 50 microns of material is removed from the first surface, wherein at least 75% of the first target surface feature is removed from the first surface during the removing of the material, by one or more of chemical etching, plasma etching, and laser etching, of the material from the first surface, and wherein the removing is performed after hot rolling is completed.
23. The method of claim 22, wherein the aluminum alloy of the continuously cast aluminum alloy article is selected from the group consisting of aluminum alloys 1XXX, 2XXX, 3XXX, 4XXX, 5XXX, 6XXX, 7XXX, 8XXX, and 9XXX, and wherein, during the removing of the material from the first surface, the continuously cast aluminum alloy article has a temperature of at least about 500 degrees Fahrenheit.
24. The method of claim 17, wherein the removing of the material from the first surface occurs by one or more of plasma etching and laser etching.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
(1) The accompanying drawings are incorporated into and form a part of the specification to illustrate several examples of the present disclosure. These drawings, together with the description, explain the principles of the disclosure. The drawings simply illustrate preferred and alternative examples of how the disclosure can be made and used and are not to be construed as limiting the disclosure to only the illustrated and described examples. Further features and advantages will become apparent from the following, more detailed, description of the various aspects, embodiments, and configurations of the disclosure, as illustrated by the drawings referenced below.
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DESCRIPTION OF DISCLOSURE
(13) This disclosure relates generally to a method for reducing or eliminating target surface features in caster strips. More particularly, the disclosure relates to a method for reducing or eliminating target surface features in caster strips in continuous casting processes. The target surface features can be any surface feature targeted for removal, including the oxide surface layer formed immediately following casting when the cast strip is exposed to the atmosphere and casting defects. The oxide surface layer often includes impurities in the continuously cast molten metal. Caster strip defects can be caused by thermal or stress introduced mold distortion or other manufactured mold imperfections regarding surface levelness. Non-limiting examples of caster strip defects include steps, ramps, bows, buckles, streaks, drag marks, protrusions, channels, valleys, and block joints. Target surface features can cause surface quality issues that render aluminum alloy sheet unacceptable for automotive and other aesthetically demanding applications requiring high surface quality.
(14) As discussed below, the process of the disclosure can provide aluminum alloy sheet meeting the high surface quality requirements of these applications by removing the target surface features before cold rolling. Removal after cold rolling can be difficult as the target surface features can be embedded by cold rolling into the surface. Like direct-chill casting, the target surface features can be removed immediately after casting but, unlike direct-chill casting, the target surface features can also be removed between hot rolling stands or from the hot rolled strip or hot band.
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(16) The caster strip 10 can comprise any aluminum alloy selected from the group of consisting of aluminum alloys 1XXX, 2XXX, 3XXX, 4XXX, 5XXX, 6XXX, 7XXX, 8XXX, and 9XXX. The caster strip 10 can, for example, be an aluminum alloy suitable for aircraft or aerospace structures, marine structures, or automotive structures. As will be appreciated, the caster strip can be other metals or metal alloys, such as steel.
(17) Each casting method forms a caster strip 10 having target surface features on each of the upper and lower cast strip surfaces 11 and 12 (depending on the casting process employed). As shown in
(18) With reference to
(19) A second treatment option is to reduce or remove the target surface feature by controlled surface treatment 24 after the caster strip 10 is treated by one or more hot rolling stands 32a-z, or is performed at a location 34 between hot rolling stands 32a-z. This treatment option is illustrated by process line 56. In the second treatment option, controlled surface treatment is generally applied between hot mill stands to the partially hot rolled strip while the strip has a temperature of from about 500 to about 1,000 degrees Fahrenheit, more generally from about 550 to about 1,000 degrees Fahrenheit, more generally from about 600 to about 1,000 degrees Fahrenheit, more generally from about 700 to about 1,000 degrees Fahrenheit, more generally from about 750 to about 1,000 degrees Fahrenheit, more generally from about 800 degrees Fahrenheit to about 1,000 degrees Fahrenheit, and even more generally from about 850 to about 1,000 degrees Fahrenheit.
(20) A third treatment option is to reduce or remove the target surface feature by controlled surface treatment 24 after processing the caster strip 10 to form hot rolled strip or hot band 36 and before cold rolling of the hot band by one or more cold rolling stands. In other words, controlled surface treatment 24 can be done in-line to the hot band 36 before the first cold rolling stand (not shown). This treatment option is illustrated by process line 60. In the third treatment option, controlled surface treatment 24 is generally applied to the (fully) hot rolled strip 36 while the strip 36 has a temperature of from about 400 to about 850 degrees Fahrenheit, more generally from about 450 to about 850 degrees Fahrenheit, more generally from about 500 degrees Fahrenheit to about 850 degrees Fahrenheit, more generally from about 550 degrees Fahrenheit to about 850 degrees Fahrenheit, more generally from about 600 degrees Fahrenheit to about 850 degrees Fahrenheit, and more generally from about 650 degrees Fahrenheit to about 850 degrees Fahrenheit.
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(22) The above treatment options are not mutually exclusive but can be combined as required by the particular application.
(23) Controlled surface treatment step 24 can include one of more of milling, sawing, chemically treating, plasma treating, laser etching, abrasively treating, or a combination thereof one or more of the opposing strip surfaces. As will be appreciated, certain of the treating techniques, such as laser etching and plasma treating, do not require physical contact with the hot strip surface while other treating techniques, such as milling, sawing, chemically treating, and abrasively treating, require physical contact.
(24) When both of the opposing caster strip surfaces are subjected to controlled surface treatment they can be treated sequentially, in any order, or substantially simultaneously. The controlled surface treatment step 24 is typically performed in line with the casting step 22; that is, treatment is performed as the cast strip moves continuously from the caster and through intervening process steps, such as hot milling, cold milling, and annealing.
(25) Controlled surface treatment 24 can remove, from the treated surface, most or all of the target surface features; that is, controlled surface treatment 24 can reduce the amount of each unit of cast article surface area occupied by one or more target surface features. While the percentage removal of target surface features depends on the finished gauge sheet requirements, controlled surface treatment typically removes at least about 0.5%, more typically at least about 1%, more typically at least about 10%, more typically at least about 25%, more typically at least about 50%, more typically at least about 65%, more typically at least about 75%, and even more typically at least about 96% of the target surface features from each of the untreated surfaces. In some applications, the target surface features are removed from only one of the surfaces. An example would be aluminum alloy sheet to be used for a car door, which requires a high-quality surface only for the door exterior and not for the door interior.
(26) The amount of material required to be removed from each surface in the controlled surface treatment step 24 to remove or eliminate target surface features can vary depending on the finished gauge sheet requirements. Typically, controlled surface treatment removes from each surface at least about 5 microns, more typically at least about 10 microns, more typically at least about 20 microns, more typically at least about 30 microns, more typically at least about 40 microns, and even more typically at least about 50 microns but typically no more than about 2,000 microns, more typically no more than about 1,750 microns, more typically no more than about 1,500 microns, more typically no more than about 1,250 microns, more typically no more than about 1,000 microns, more typically no more than about 750 microns, more typically no more than about 500 microns, more typically no more than about 400 microns, more typically no more than about 300 microns, more typically no more than about 200 microns, more typically no more than about 175 microns, more typically no more than about 150 microns, more typically no more than about 125 microns, and even more typically no more than about 100 microns of material while maintaining a substantially constant width of the cast article. In some applications, the surfaces have different amounts of material removed due to different finished gauge surface requirements.
(27) Commonly, the treating step is done directly after casting of the strip, with no intermediate material removal steps, such as hot milling.
(28) In step 48 of
(29) Controlled surface treatment step 24 can comprise one or more operations. For example, the treatment step 24 can be conducted only one time, such as shown by process lines 52, 56, or 60 or in multiple of the locations shown in
EXPERIMENTAL
(30) The following examples are provided to illustrate certain aspects, embodiments, and configurations of the disclosure and are not to be construed as limitations on the disclosure, as set forth in the appended claims. All parts and percentages are by weight unless otherwise specified.
(31) A trial was performed using aluminum alloys 5182 (as coil A-17-046) and 6016 (as coils C-15-012 and C-15-015).
(32) All coils were treated by special large brushes to remove the oxide layer (mechanically) and the surface brushed samples were painted, in accordance with an automotive manufacturer's specifications, with gloss black paint and then evaluated against DC standards. The painted coils were determined to meet the MINIMAL acceptance per GM specifications.
(33) A number of variations and modifications of the disclosure can be used. It would be possible to provide for some features of the disclosure without providing others.
(34) For example, in one alternative embodiment, the treating step is performed between hot mill stands, between a hot mill stand and cold mill stand, or between cold mill stands.
(35) The present disclosure, in various aspects, embodiments, and configurations, includes components, methods, processes, systems and/or apparatus substantially as depicted and described herein, including various aspects, embodiments, configurations, subcombinations, and subsets thereof. Those of skill in the art will understand how to make and use the various aspects, aspects, embodiments, and configurations, after understanding the present disclosure. The present disclosure, in various aspects, embodiments, and configurations, includes providing devices and processes in the absence of items not depicted and/or described herein or in various aspects, embodiments, and configurations hereof, including in the absence of such items as may have been used in previous devices or processes, e.g., for improving performance, achieving ease and\or reducing cost of implementation.
(36) The foregoing discussion of the disclosure has been presented for purposes of illustration and description. The foregoing is not intended to limit the disclosure to the form or forms disclosed herein. In the foregoing Detailed Description for example, various features of the disclosure are grouped together in one or more, aspects, embodiments, and configurations for the purpose of streamlining the disclosure. The features of the aspects, embodiments, and configurations of the disclosure may be combined in alternate aspects, embodiments, and configurations other than those discussed above. This method of disclosure is not to be interpreted as reflecting an intention that the disclosure requires more features than are expressly recited in each claim. Rather, as the following claims reflect, inventive aspects lie in less than all features of a single foregoing disclosed aspects, embodiments, and configurations. Thus, the following claims are hereby incorporated into this Detailed Description, with each claim standing on its own as a separate preferred embodiment of the disclosure.
(37) Moreover, though the description of the disclosure has included description of one or more aspects, embodiments, or configurations and certain variations and modifications, other variations, combinations, and modifications are within the scope of the disclosure, e.g., as may be within the skill and knowledge of those in the art, after understanding the present disclosure. It is intended to obtain rights which include alternative aspects, embodiments, and configurations to the extent permitted, including alternate, interchangeable and/or equivalent structures, functions, ranges or steps to those claimed, whether or not such alternate, interchangeable and/or equivalent structures, functions, ranges or steps are disclosed herein, and without intending to publicly dedicate any patentable subject matter.