Apparatus and method for surface treatment of flat rolled metal strip

Abstract

A work roll (200) in a rolling process of a steelmaking process has a surface with a negative of a pattern where the pattern is imparted onto a surface of a steel strip (300) that is rolled between the work roll (200) and another roller (206) under a prescribed rolling pressure. The resulting steel strip has a surface with a pattern where the pattern provides targeted wettability properties for the steel strip that can include any of hydrophobic, super hydrophobic, hydrophilic, or super hydrophilic.

Description

APPARATUS AND METHOD FOR SURFACE TREATMENT OF FLAT ROLLED METAL STRIPPRIORITY

[0001] This application claims priority to U.S. Provisional Patent Application Serial No. 63 / 673,174, filed July 19, 2024, entitled “Apparatus and Method for Surface Treatment of Flat Rolled Metal Strip,” the disclosure of which is incorporated by reference herein.BACKGROUND

[0002] The rolling of strip steel in the steelmaking process occurs after the initial steel is cast and formed into ingots or slabs. During rolling, the steel slab or ingot is passed through a series of rolling mills, where it undergoes gradual reduction in thickness. This mechanical deformation refines the steel’s microstructure, improves its mechanical properties, and imparts desired dimensions. The result is a uniform strip steel product ready for various applications across industries. During the steelmaking process, the steel may also be coated, such as steel with a galvanized or aluminized coating, or the steel may remain bare or uncoated. While a variety of steels and methods for steelmaking have been made and used, it is believed that no one prior to the inventor(s) has made or used an invention as described herein.SUMMARY

[0003] In use, corrosion of metallic materials can be a concern and may occur when water or other liquids wet the metal’s surface. To combat corrosion, some rolled steel may be coated as mentioned above. In some instances, the coating may be a polymeric coating or other type of coating. However, polymeric coatings as well as some other types of coatings have limitations associated with their durability. As described further below, the present application describes an apparatus and method to combat corrosion in a steel strip without the durability limitations associated with coatings. It also provides for a way to process or treat a moving steel strip to achieve the desired effects without requiring the steel strip to stop or be stationary for a set time period.

[0004] The apparatuses and methods allow for altering the surface characteristics of the steel in terms of wettability, and can produce a strip steel in a rolling process with a hydrophobic or super hydrophobic surface, which can provide corrosion resistance. In other examples the apparatus and method can produce a strip steel in a rolling process with a hydrophilic or super hydrophilic surface to provide different benefits as described below.

[0005] More specifically, a work roll is patterned with a negative of a desired pattern to impart a surface texture onto a flat rolled steel strip, also referred to as a steel strip. The ultimate surface texture imparted to the steel, in some instances, provides hydrophobic properties, while in other instances, provides hydrophilic properties. By patterning the work roll with the negative of the desired pattern, the desired pattern is applied or imparted onto the surface of a moving steel strip which results in the flat rolled steel strip having a desired surface texture or pattern. In this manner the steel strip can be textured — e.g., a pattern imparted thereto — in a continuous process where the steel strip maintains movement while be texturized as opposed to stopping the steel strip and applying static pressure to a stationary steel strip to impart the texture or pattern. As mentioned, this pattern is selected based on the desired wettability properties it provides to the steel surface.DESCRIPTION OF DRAWINGS

[0006] While the specification concludes with claims which particularly point out and distinctly claim the invention, it is believed the present invention will be better understood from the following description of certain examples taken in conjunction with the accompanying examples and figures.

[0007] FIG. l is a schematic view of a process for rolling and treating steeling to form steel strips that are formed into coils.

[0008] FIG. 2 is perspective view of a work roll having a negative of a pattern ingrained onto the surface of the work roll.

[0009] FIG. 3 is an enlarged view of the surface of the work roll of FIG. 2 showing the negative of the pattern.

[0010] FIG. 4 is an enlarged view of the surface of an exemplary steel strip after having a pattern ingrained on the surface of the strip steel from the work roll of FIG. 2.

[0011] FIG. 5 is a schematic view of a method for processing or treating a strip steel to impart a surface texture to the strip steel to provide desired wettability properties.

[0012] FIGS. 6A, 6B, 6C, and 6D are enlarged views of an exemplary work roll, such as the work roll of FIG. 2, showing a negative of a pattern ingrained onto the surface of the work roll; FIGS. 6A and 6C show a scanning electronic microscopic image while FIGS. 6B and 6D show a three-dimensional laser confocal image.

[0013] FIG. 7A, 7B, 7C, and 7D are enlarged views of an exemplary strip steel, such as the strip steel of FIG. 2, showing a pattern ingrained onto the surface of the strip steel; FIGS. 7A and 7C show a scanning electronic microscopic image while FIGS. 7B and 7D show a three-dimensional laser confocal image.

[0014] FIGS. 8 A and 8B are enlarged views of an exemplary work roll, such as the work roll of FIG. 2, with a negative of a pattern ingrained onto the surface of the work roll, showing water droplets on the surface.

[0015] FIGS. 9A and 9B are enlarged views of an exemplary strip steel, such as the strip steel of FIG. 2, with a pattern ingrained onto the surface of the strip steel, showing water droplets on the surface.

[0016] The figures are not intended to be limiting in any way, and it is contemplated that various embodiments of the invention may be carried out in a variety of other ways. The accompanying figures incorporated in and forming a part of the specification show aspects of the present invention, and together with the description serve to explain the principles of the invention; it being understood, however, that this invention is not limited to what is shown in the figures.DETAILED DESCRIPTION

[0017] The following description of certain examples of the invention should not be used to limit the scope of the present invention. Other examples, features, aspects, embodiments, and advantages of the invention will become apparent to those skilled inthe art from the following description. As will be realized, the invention is capable of other different and obvious aspects, all without departing from the invention. Accordingly, the examples, figures, and descriptions should be regarded as illustrative in nature and not restrictive.

[0018] Referring to FIG. 1, a process (100) for rolling and treating steel to form steel strips includes casting slabs or ingots of steel (102) followed by hot rolling (104), cold rolling (106), annealing (108), coating (110), and coiling (112). Some of these steps are optional and additionally the steps may be performed in different sequences than illustrated. In some instances, the coiled steel can be subject to further processing (114) and in doing so be unwound and subject to further heating, cooling, and / or rolling before re-coiling (116). One example of such further processing is processing the coiled steel rolls in a temper mill or rolling mill. In one version, the steel treatment discussed herein occurs as part of the cold rolling shown in FIG. 1. Still in other versions, the steel treatment discussed further below occurs after the initial coiling in further processing (114), e.g., as part of processing in a temper mill or rolling mill. In view of the teachings herein, other locations and times during the steelmaking process for accomplishing the steel treatment described herein will be apparent to those of ordinary skill in the art.

[0019] Referring now to FIGS. 2 and 3, a work roll (200) used with the steel treatment process includes a surface (202) that is ingrained with a negative of a pattern (204). FIG. 3 illustrates an enlarged portion of the surface of the work roll (200) showing an exemplary negative of a pattern (204) included on the surface (202). For clarity, a negative of a pattern may also be thought of as the counter-pattern or opposite-pattern such that contact with the negative of a pattern results in the desired pattern, or positive of the pattern, being applied or transferred to the surface that contacted the negative of the pattern. FIGS. 6A, 6B, 6C, and 6D illustrate enlarged images of an exemplary negative of a pattern (504) with FIGS. 6A and 6C showing scanning electron microscope images of the surface of the work roll at different magnifications, while FIGS. 6B and 6D show three-dimensional laser confocal images of the surface of the work roll at different magnifications. In one example, the negative of a pattern (504)shown in FIGS.6A-6D represents the negative of a pattern (204) that is on the surface (202) of the work roll (200).

[0020] The pattern can be configured to provide desired wettability properties. For instance, how prone or resistant the patterned steel is to wetting, or in other words how hydrophobic or hydrophilic the patterned steel may be. To ingrain the negative of the pattern (204, 504) onto the surface (202) of the work roll (200), femtosecond laser bursts may be used to cut the negative of the pattern (204, 504) into the surface (202). Use of the femtosecond laser to impart surface texture to a surface such as the surface (202) of the work roll (200) can be referred to as laser induced periodic surface structure (also referred to as “LIPSS”). By way of example only, and not limitation, in some versions, the negative of the pattern (204, 504) is a combination of nano scale and micro scale structures. One example structure system has a period of less than 100 microns with sub-features of less than 15 microns, for instance as shown in FIGS. 6A- 6D.

[0021] In some versions, it is desirable to provide a strip steel with a hydrophobic or super hydrophobic surface. The term “super hydrophobic” as used herein shall be understood to mean when the contact angle of the wetting agent, e.g., water, with the steel surface is greater than 150 degrees, while the term “super hydrophilic” as used herein shall be understood to mean when the contact angle of the wetting agent, e.g., water, with the steel surface is less than 5.

[0022] Certain patterns ingrained onto the steel surface can provide these properties. One such pattern is referred to as the lotus leaf pattern (as can been seen in the article “Lotus leaf inspires scientists to create world's first self-cleaning metals,” from Phys.org, June 28, 2016, available at https: / / phys.org / news / 2016-06-lotus-leaf-scientists-world-self- cleaning.html). Steel with a hydrophobic or super hydrophobic surface provides benefits in terms of increased corrosion resistance as well as reduction in biological growths that might survive on wet surfaces. In some other versions, it is desirable to provide a strip steel with a hydrophilic or super hydrophilic surface. Certain patterns ingrained onto the steel surface can provide these properties. Steel with a hydrophilic or super hydrophilic surface provides benefits in terms of improved heat transfer,cleanability, compatibility with oil, and with channeling fluid flow on the steel surface. Exemplary patterns may be seen in, “Femtosecond laser-chemical hybrid processing for achieving substrate-independent superhydrophobic surfaces,” Weng, Wx. et al., J. Cent. South Univ., vol. 31, pg. 1-10, January 19, 2024, available at https: / / doi.org / 10.1007 / sl l771-023-5527-x; and “Ultrahydrophobic Surface. Effects of Topography Length Scales on Wettability,” Didem Oner et al., American Chemical Society, August 26, 2000, available at https: / / pubs.acs.org / doi / 10.1021 / la000598o.

[0023] Referring to FIGS. 2 and 4, an example strip steel (300) is generally smooth on both its top and bottom surfaces prior to entering the rolling station where work roll (200) is positioned above another roller (206). As mentioned above, work roll (200) has a surface (202) that is ingrained with a negative of a pattern (204, 504). As the strip steel (300) is passed through the rolling nip created by work roll (200) and roller (206) it is subjected to high pressure and a pattern (304, 604) is imparted onto the surface (302) of the strip steel (300). In some instances the pattern (304, 604) may be imparted onto both surfaces of the strip steel (300), for instance by using multiple work rolls (200) such that one contacts each surface of the steel, e.g., by either replacing roller (206) with another work roll (200) or by an additional processing stage where a second work roll (200) and roller (206) are used to impart the pattern on the other side. As mentioned, the negative of the pattern (204, 504) imparts the pattern (304, 604), and the pattern can be selected based on desired surface properties for wettability as described above. By way of example, FIGS. 7A, 7B, 7C, and 7D illustrate enlarged images of an exemplary pattern (604) ingrained onto the surface (302) of the steel strip (300) with FIGS. 7A and 7C showing scanning electron microscope images of the surface of the strip steel at different magnifications, while FIGS. 7B and 7D show three-dimensional laser confocal images of the surface of the steel strip at different magnifications. In one example, the pattern (604) shown in FIGS.7A-7D represents the opposite of the negative of a pattern (504) that can be on the surface (202) of the work roll (200).

[0024] FIG. 5 shows a block diagram of a method (400) for treating or processing a strip steel to impart a surface texture to the strip steel to provide desired wettability properties. A first step (402) is obtaining the flat rolled steel strip. This could include, in someversions, starting with a hot band of steel after hot rolling and cooling, or starting with a previously coiled roll of flat rolled steel strip. In another step (404), a work roll (200) for a rolling section or operation is obtained and installed in the rolling operation for use. As mentioned above, the work roll (200) has a negative of a pattern, which is ingrained on the work roll (200) by using a femtosecond laser for example. As discussed above, the specific negative of the pattern will be selected based on the desired wettability properties for the steel surface after the rolling operation is complete. In another step (406), a desired rolling pressure is set. The desired rolling pressure will be adequate to impart the pattern onto the strip steel surface when rolling the strip steel using the work roll (200). In at least one example as shown in FIGS. 6A- 6D and 7A-7D, the pressure is set to approximately 28.6 kilopounds per square inch (ksi). Of course other pressures will be understood to those of ordinary skill in the art in view of the teachings here.

[0025] With the strip steel, the work roll (200), and the rolling pressure setting in place, in another step (408) the strip steel is rolled between the work roll (200) and another roll or surface. Then in another step (410), the pattern is imparted to the strip steel during the rolling operation and with the strip steel moving through the rolling process. In some versions, in another step the steel strip may be pretreated with certain surface features that may enhance the finished steel or that may aid in the rolling and imparting the pattern onto the steel surface, for example such as use of lubricants. Other steps or modifications of the processes and methods that can be incorporated into the method (400) may include processing “dry” and / or adjusting processing speeds to impact the contact time of the work roll with the steel surface. Still other steps or modifications of the processes and methods will be apparent to those of ordinary skill in the art in view of the teachings herein.

[0026] It should be understood that any one or more of the teachings, embodiments, examples, etc. described herein may be combined with any one or more of the other teachings, embodiments, examples, etc. that are described herein. The following-described teachings, embodiments, examples, etc. should therefore not be viewed in isolation relative to each other. Various suitable ways in which the teachings herein may becombined will be readily apparent to those of ordinary skill in the art in view of the teachings herein. Such modifications and variations are intended to be included within the scope of the claims.

[0027] Having shown and described various examples of the present invention, further adaptations of the methods and systems described herein may be accomplished by appropriate modifications by one of ordinary skill in the art without departing from the scope of the present invention. Accordingly, the scope of the present invention should be considered in terms of the following claims and is understood not to be limited to the details of structure and operation shown and described in the specification and drawings.

Claims

I / We claim:

1. A rolled metal strip comprising a surface, wherein the surface includes a pattern that provides a texture to the surface, wherein the pattern provides the surface of the rolled metal strip with targeted wettability properties.

2. The rolled metal strip of claim 1, wherein the targeted wettability properties comprise hydrophobic or super hydrophobic.

3. The rolled metal strip of claim 2, wherein the contact angle of a wetting agent with the surface is greater than 150 degrees.

4. The rolled metal strip of claim 1, wherein the targeted wettability properties comprise hydrophilic or super hydrophilic.

5. The rolled metal stirp of claim 4, wherein the contact angle of a wetting agent with the surface is less than 5 degrees.

6. The rolled metal strip of claim 1, wherein the rolled metal strip includes an aluminized coating.

7. The rolled metal strip of claim 1, wherein the rolled metal strip includes a galvanized coating.

8. The rolled metal strip of claim 1, wherein the rolled metal strip includes a galvalume coating.

9. The rolled metal strip of claim 1, wherein the rolled metal strip includes a tinplate or tin free steel (chrome) coating.

10. A work roll for use in treating a rolled metal strip comprises a negative of a pattern that is configured to impart the pattern on the rolled metal strip while the rolled metal strip moves past the work roll, wherein the pattern imparts targeted wettability properties on the rolled metal strip.11 . The work roll of claim 10, wherein the negative of the pattern is configured to impart the pattern on the rolled metal strip such that a surface of the rolled metal strip with the pattern is hydrophobic or super hydrophobic.

12. The work roll of claim 11, wherein the contact angle of a wetting agent with the surface of the rolled metal strip is greater than 150 degrees.

13. The work roll of claim 10, wherein the negative of the pattern is configured to impart the pattern on the rolled metal strip such that a surface of the rolled metal strip with the pattern is hydrophilic or super hydrophilic.

14. The work roll of claim 13, wherein the contact angle of a wetting agent with the surface of the rolled metal strip is less than 5 degrees.

15. The work roll of claim 10, wherein the negative of the pattern is ingrained onto a surface of the work roll using a femtosecond laser.

16. A method of processing a rolled metal strip comprises; a. rolling the rolled metal strip using a work roll having a negative of a pattern on a surface of the work roll, wherein the pattern is configured to provide targeted wettability properties to the rolled metal strip; b. conducting the rolling at a target rolling pressure; and c. imparting the pattern on the rolled metal strip from the contact and rolling pressure of the work roll.

17. The method of claim 16 wherein the targeted wettability properties comprise hydrophobic or super hydrophobic.

18. The method of claim 17, wherein the contact angle of a wetting agent with the surface is greater than 150 degrees.

19. The method of claim 16, wherein the targeted wettability properties comprise hydrophilic or super hydrophilic.

20. The method of claim 19, wherein the contact angle of a wetting agent with the surface is less than 5 degrees.

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