Additive manufacture of metal coil or strip for cold rolling

Abstract

Methods of cold-rolling metal strip or sheet material, and more particularly to methods of preparing metal strip or sheet material for subsequent cold rolling. The methods of making the metallic coil or strip can be by either a powder-based DED or WAAM additive manufacturing process. The coil or strip can have has a graded composition and / or graded physical property and / or a graded metallurgical property in at least one dimension of the length and / or width and / or thickness of the coil or strip.

Description

ADDITIVE MANUFACTURE OF METAL COIL OR STRIP FOR COLD ROLLINGCROSS-REFERENCE TO RELATED PATENT APPLICATIONS

[0001] This application claims priority to U.S. Patent Appl. Serial No. 63 / 660,026, filed June 14, 2024, entitled “Additive Manufacture Of Metal Coil Or Strip For Cold Rolling,” which patent application is commonly owned by the owner of the present invention. This patent application is incorporated herein in its entirety.FIELD OF THE INVENTION

[0002] This invention relates generally to methods of cold-rolling metal strip or sheet material, and more particularly to methods of preparing metal strip or sheet material for subsequent cold rolling.BACKGROUND OF INVENTION

[0003] Cold-rolled, flat-rolled metal strip and sheet materials constitute the most widely-used types of metallic raw materials in manufactured products containing metals and are key raw materials in an enormous number and variety of capital and consumer goods that span almost every industry sector. Such flat-rolled metals are manufactures from diverse alloys including steel, aluminum, copper / brass, and specialty metals. They are used in subsequent stamping and forming operations to create key assembly components in numerous other capital / consumer goods, including commercial / military aircraft, automobiles, building and energy infrastructure, electronics, computers, appliances, kitchenware, medical instruments, food packaging, and beverage cans, among others.

[0004] Currently, the cold rolling processes represents a final stage in the manufacture of coiled strip or sheet before it is cut to size and formed into user components. The cold rolling process requires the input of “hot-band” coils that are produced through a sequence of upstream processes that involve melting of raw materials or scrap to create molten metal, casting the molten metalinto slabs (or ingots), and then hot rolling these slabs to produce the hot-band coils. Hot rolling is performed above recrystallization temperature to facilitate bulk reduction in thickness, while cold rolling is performed below recrystallization temperature to achieve desired mechanical properties and surface finish while further reducing the thickness to precise dimension. The conventional approach to producing hot-band coils (z.e., melting, casting, and hot rolling prior to cold rolling) does not allow for the production of chemical composition graded or mixed-alloy hot-band coils for input to the cold rolling process. The conventional hot-rolled coil is typically fairly uniform in its properties throughout and often special care is taken during the hot rolling operation to minimize any deviations from a fixed uniform standard of both composition and properties throughout the width, thickness and length of the coil. As a result, the convention melting / casting / hot-rolling approach does not provide for manufacturing cold-rolled strip and sheet that is compositionally graded. The conventional melting / casting / hot-rolling approach also does not lend itself to creating small or customized batches of stock coil material wherein only a small portion of a customary-sized coil may be needed, but would be commercially unfeasible.

[0005] The conventional approach has further practical limitations including the need for specialized and costly equipment for each of the melting, casting and hot rolling operations. Each of these operations are enormously capital-intensive and physically very large and collectively require sizable facilities to house and operate these operations. Coordination among the melting / casting / hot-rolling operations is also required, as events occurring at the melt operation may negatively impact the casting, and events occurring during the casting operation may have detrimental impact on subsequent hot rolling. Each operation requires numerous skilled and dedicated technicians who must carefully monitor and manage the processes to assure that a final hot-roll coil is produced having the desired uniform chemistry and properties throughout according to specifications.

[0006] In addition to the specialized processing equipment itself, each of these melting, casting, and hot rolling operations require specialized ancillary equipment and processes to handle, test, transport and control the chemistry and properties of the material at each stage of operation, adding to the cost and complexity of the overall process.SUMMARY OF INVENTION

[0007] A metallic coil in strip or sheet prepared for use as input to a cold rolling operation is made by additive manufacturing instead of melting, casting and hot rolling.

[0008] The conventional melting, casting, and hot rolling operations can be replaced with a hybrid manufacturing process (such as a single hybrid manufacturing process) that “prints” customized hot-band coils for direct input to cold rolling operations.

[0009] The additive manufacturing processes may include powder-based directed energy deposition (DED) or wire arc additive manufacturing (WAAM). A milling-type machining operation can be integrated with the build process, resulting in hybrid manufacturing.

[0010] The inventive method enables direct production of property or chemical composition graded coils which, when cold rolled, can allow for heretofore non-existent manufacture of stamped and formed strip and / or sheet metal components that exploit the unique advantage of location-customizable attributes distributed throughout the geometries of the formed end-user components according to specific application needs. Such location-customization attributes may include, but are not limited to, formability, density, weight distribution, thickness, corrosion resistance, electric / magnetic properties, high temperature resistance, and / or other customizable properties that result from tailored metallic chemical composition and / or location-specific metallurgical and / or physical gradations which may be imparted throughout the length, width or thickness (or combinations thereof) of the strip / sheet using the additive manufacturing processes to create coils for direct input into cold rolling processes.

[0011] The direct formation of a metallic coil through additive manufacturing realizes numerous practical benefits apart from the customization advantages discussed above. The direct printing of a strip or sheet in coil form by additive manufacturing avoids the need for traditional bulk metal melting equipment and facilities, as well as those typically required for casting and hot rolling. The coils made by additive manufacturing can be readily produced in smaller customizable sizes in facilities that command a much smaller footprint than needed for conventional melting / casting / hot rolling processes.

[0012] A metallic coil made by additive manufacturing can be alternatively prepared with uniform chemistry but variable physical or metallurgical properties that yield beneficial properties when subsequently cold rolled for use in end products. It is also envisioned that combinations of chemical, physical and metallurgical gradients can be imparted to the coil during additive manufacturing that respond to subsequent cold rolling in ways that yield predictable and beneficial attributes to the cold rolled coil and eventual stamped or formed end products made from the coil.

[0013] Examples of diverse products made from strip and / or sheet material that derive unique and innovative benefits in cost, strength, weight / density, electrical properties, corrosion resistance, high-temperature resistance, or other properties can be realized as a result of the additive manufacturing process used to produce coiled metallic strip or sheet material having graded chemical composition and / or metallurgical properties and / or physical properties as input material to cold rolling of such metal strip and / or sheet. Such products include, but are not limited to: cookware, knives and sharp edges, aerospace vehicle and propulsion components, ship / seaborne vessel hulls; battery current collectors, beverage cans, and cladded sheet products to name a few.

[0014] In general, in one embodiment, the invention features a method of making a metallic coil or strip precursor for a cold rolling operation. The method includes using additive manufacturing to directly fabricate a three-dimensional coil or strip in coil form having a predetermined length,thickness and width.

[0015] Implementations of the invention can include one or more of the following features:

[0016] The coil or strip can have a graded composition and / or graded physical property and / or a graded metallurgical property in at least one dimension of the length and / or width and / or thickness of the coil or strip. The coil or strip can be subsequently processed by cold rolling the coil or strip.

[0017] An end product can be subsequently made from portions of the cold-rolled coil or strip and wherein the end product has geometric regions of different chemical composition.

[0018] The additive manufacturing process can be powder-based directed energy deposition (DED).

[0019] The additive manufacturing process utilizes one or more powders selected from the group consisting of powders of stainless steel, tool steels, carbon and low carbon steels, titanium alloys, nickel-base alloys, aluminum alloys, cobalt-based alloys, precious metal alloys, copper alloys, and cobalt-chromium alloy.

[0020] The additive manufacturing process can utilize at least two different types of powders of the one more powders. The ratio of the at least two different types of powders can be varied during the additive manufacturing process.

[0021] The additive manufacturing process can be wire arc additive manufacturing (WAAM).

[0022] The additive manufacturing process can utilize one or more wires selected from the gr7up consisting of wires of stainless steel, tool steels, carbon and low carbon steels, titanium alloys, nickel-base alloys, aluminum alloys, cobalt-based alloys, precious metal alloys, copper alloys, and cobalt-chromium alloy.

[0023] The additive manufacturing process can utilize at least two different types of wires of the one more wires. The ratio of the at least two different types of wires can be varied during the additive manufacturing process.

[0024] In general, in another embodiment, the invention features a method of making a metallic coil or strip by either a powder-based directed energy deposition (DED) or wire arc additive manufacturing (WAAM) process. The coil or strip is direct printed along a spiral path layer-by- layer to build a three-dimensional coil or strip of metallic material having a coiled length, a thickness and a width. The metallic coil is subsequently cold rolled.

[0025] In general, in another embodiment, the invention features a method of making a product. The method includes making a metallic coil or strip by the above-described method of making a metallic coil or strip. The method further includes utilizing the metallic coil or strip in a product selected from the group consisting of tubes, cookware, knives / blade edges, aircraft and propulsion components, marine vessel panels, battery current collector sheets, beverage cans, and cladded products.

[0026] In general, in another embodiment, the invention features a product made from a portion of at least one layer of additive manufactured and cold-rolled metallic sheet material. The product has a predetermined geometric shape. The portion of metallic sheet material used in making the product has regions of different chemical compositions and / or different physical properties and / or different metallurgical properties derived from the additive manufacturing and cold rolling processes corresponding to different regions of the predetermined geographic shape of the product.

[0027] In general, in another embodiment, the invention features a method of making a product from cold-rolled metallic coil or strip material. The method includes directly printing a coil or strip precursor using an additive manufacturing process without hot-rolling and having a gradedchemical composition in at least one length, width, or thickness dimension of the precursor coil or strip. The method further includes subsequently cold rolling the printed coil or strip. The method further includes further processing the cold-rolled strip to form the product having at least two regions of different chemical composition resulting from the direct printing of the coil or strip precursor.BRIEF DESCRIPTION OF THE DRAWINGS

[0028] These and other features and advantages will be better appreciated when considered in connection with the detailed description and drawing figures, in which:

[0029] FIG. 1 is a schematic flow diagram of an embodiment.

[0030] FIGS. 2-4 are schematic illustrations showing the progression of making a metallic coil by a powder-based DED laser additive manufacturing process.

[0031] FIGS. 5-7 are schematic illustrations showing the progression of making a metallic coil by a WAAM additive manufacturing process.

[0032] FIG. 8 is a schematic of a coil produced by an additive manufacturing process with chemical composition and / or metallurgical and / or physical gradient features in up to three dimensions.

[0033] FIG. 9A is a schematic of DED fabrication of a chemical composition graded straight wall.

[0034] FIG. 9B shows the gradient transition utilized in the schematic of FIG. 9B.

[0035] FIG. 9C is a photograph the manufacture of multi-materials DED made by the process shown in FIG. 9A.

[0036] FIG. 10A shows two 76 x 25 x 3 mm walls (each with 50% SS316L and 50% IN718) made by the process shown in FIG. 9A (with the lower and upper regions of walls are 100% SS316L and IN718, respectively).

[0037] FIG. 10B is the walls shown in FIG. 10A after machining to 1 mm thickness.

[0038] FIG. 11A shows a laboratory mill used for the process for cold rolling of the machined 50% SS316L / 50% IN718 DED sample.

[0039] FIG. 11B-11C show the two samples before and after cold rolling, respectively.

[0040] FIG. 11D shows the a-d orientation of the two cold-rolled samples for the thickness data collected after 4 passes for the first sample #1 and 7 passes for the second sample.

[0041] FIG. 12 shows SEM images (at planes in FIG. 11C) for the first cold-rolled samples at 100% IN718 region, 50% IN718 / 50% SS316L region, 100% SS316L region.DETAILED DESCRIPTION

[0042] A metallic coil and / or strip for use as input to a cold rolling operation is produced by additive manufacturing process(es) in order to control the composition and / or metallurgical and / or physical properties of the coil and / or strip as a precursor to the subsequent cold rolling operation. The metallic coil and / or strip made by additive manufacturing in preparation for subsequent cold rolling is a departure from the conventional approach of using melting, casting and hot rolling processes to fabricate and prepare the coil for cold rolling. None of these traditional processes and related equipment and facilities are required when making a coil and / or strip by additive manufacturing.

[0043] FIG. 1 is a schematic flow diagram that shows primary steps in making a metallic coil and / or strip by additive manufacturing that is subsequently cold rolled and then further processed into end products. Raw material 10 is provided in a predetermined composition and form suitable for making a coil or strip 12 by the selected additive manufacturing process 14. For example, the raw material 10 may comprise metallic powder of a single composition, and / or a blend of different compositions and / or pre-alloyed particles. The powders may also vary in their physical and / or metallurgical properties in addition to or in lieu of varying in chemical composition. The rawpowder may be mixed ahead of time or in-line with the feed of the powder to the additive manufacturing process 14. There may be a single feed stream 16 or there may be multiple streams 16 of powder fed to the additive manufacturing process. A further example provides the raw material 10 in the form of one or several wires of metallic material of one or more predetermined compositions and / or varied metallurgical and / or physical properties which come together to provide the additive manufacturing process 14 with the desired composition during operation of the process.

[0044] Still referring to FIG. 1, the raw material 10 is delivered to a print head 18 (which includes an electric arc torch in the case of WAAM) of an additive manufacturing process 14, where it is locally melted and deposited to form the coil or strip 12. The coil or strip 12 is supported on a platen 20 and there is relative movement between the print head 18 and platen 20 so that the melted metal deposits along a path defining the shape of the strip or coil 12. For example, the print head 18 can be movable in X-Y-Z axes and its position and speed controlled to trace the shape of the coil or strip 12 and build several layers to develop a three-dimensional print of the coil or strip of predetermined length, thickness and width. As the print head 18 traverses the path, the composition and / or properties of the material fed to the print head can be adjusted to yield a coil and or strip that varies in composition in any or all of the X-Y-Z directions of the coil / strip. Alternatively, the platen can move in a pre-determined manner while the print head remains stationary to achieve the same desired relative motion and production outcome.

[0045] FIG. 1 also illustrates how once the coil or strip 10 is printed, it is fed as input to a cold rolling operation 22 (with or without being first re-wound to form a tightly wrapped coil), where the thickness of the coil or strip 10 is reduced to develop the desired thickness and cold-rolled physical properties of the coil or strip 10 for use in subsequent cutting / stamping / shapingoperations 24 to form end products 26 with varying composition and physical attributes geometrically strategically located to best suit the end product 26.DED Additive Manufacturing Process

[0046] FIGS. 2-4 schematically illustrate a powder directed energy deposition (powder DED) additive manufacturing process 14’ used to fabricate the coil or strip 12. FIG. 2 is a schematic of a method to fabricate first build layer of a chemical composition graded hot-band coil via hybrid manufacturing based on powder DED and integrated machining. Two of an arbitrary number of powder feed nozzles 17 are shown, and the build substrate is not shown.

[0047] FIG. 2 shows the first layer of the coil or strip 12 being produced where a plurality of powder feed nozzles 17 (only two shown here for illustrative purposes) direct a metered flow (or flows) of metallic powder of predetermined compositions to a focused, incident DED laser beam 28 which locally melts the powders at the incident region and deposits the molten metal initially onto a solid build substrate (build platform) in a predetermined spiral or coil-shaped pattern whereupon the metal solidifies to form the initial layer (or partial layer) of the coil or strip 12. FIG. 2 indicates the start (or finish) location 21 for each layer only for illustrative purposes, and that such start (or finish) location 21 may or may not correspond to the start (or finish) of the deposition process. FIG. 2 further shows current layer build location 19, build layer height 23, build layer with 25, and variable space 27 between printed coil windings (to facilitate build deposition and allow machining on the surface).

[0048] FIGS. 3-4 show the DED process continuing to deposit additional layers on top of the layers previously deposited and solidified by the DED process to fabricate the metal coil or strip 12 by the additive manufacturing (3D printing) techniques, namely DED in the case of FIGS. 2- 4. FIG. 3 depicts an intermediate stage in the fabrication of an arbitrary number of build layers.FIG. 4 depicts the final stage in the fabrication of an arbitrary number of build layers. Machining process is not shown in FIGS. 3-4.

[0049] The DED technique allows for the controlled chemical composition grading type deposition of multiple metal alloys (or only the deposition of a single alloy) along the length of the spiral, as well as through the vertical height of the spiral in the case of multiple deposited layers. FIG. 8 schematically illustrates such a coil or strip 12 that may be made by the DED process, where controlled grading of properties including, but not limited to chemical and / or metallurgical and / or electrical and / or magnetic and / or physical properties can be achieved in one or more of the X-Y-Z directions of the coil or strip 12 at time of printing the coil or strip 12 in coordination with the impact that the subsequent cold rolling operation and subsequent cutting / stamping / forming / bending / shaping operations that will be used to form the end product with the gradient being geometrically positioned in the coil to develop desired diverse material properties in the end product. As oriented in FIG. 8, length-wise chemical compositional gradient 81x, width-wise chemical compositional gradient 81y, and thickness-wise (or gauge-wise) chemical composition gradient 81z are in the X-, Y-, and Z- directions, respectfully.

[0050] Examples of products benefitting from the additive manufacturing processes are discussed below. A particular advantage that can be achieved by additive manufacturing is that the coil or strip can be directly formed without the need for prerequisite melting, casting and hot-rolling processes normally used to produce hot band coils or strips for input to the cold rolling process. Instead, the coil or strip 12 is directly manufactured using DED without these prerequisite processes and further benefiting from the ability to tailor the chemical composition gradient in any portion and in any dimension of the printed coil or strip 12 with relative ease. This ability to control and create a customized chemical composition profile of the coil or strip 12 enables coil or strip 12 to respond favorably to the subsequent cold rolling product manufacturing operationsand be geometrically placed to create an end product that has regions of different chemical composition strategically placed in the product to benefit its manufacture and / or its desired end use.

[0051] FIGS. 2-4 further schematically illustrate a milling operation 30 than can be performed on the coil or strip to control the dimension and / or improve the surface finish of the side and / or top faces of the coil or strip 12. The milling operation may comprise one or more milling cutters and / or grinders that operate on one or more exterior faces of the solidified portion of the coil or strip preferably at a location trailing the printing to remove material to improve the surface finish and / or achieve requisite dimensions on the inner and / or outer surface of the coil or strip 12 as well as those constituting the interlayer deposition surfaces of the coil or strip 12. The milling operation may advantageously be performed in-line with the deposition of the material as part of the 3D fabrication process including following the deposition and solidification of each layer of the coil or strip 12 and may move in concert with the movement of the printing head or platen to adjust the thickness dimension and prepare the previously deposited coil or strip 12 material for the deposition of each successive layer of metallic material in building the coil or strip 12.

[0052] As illustrated in FIGS. 2-4, the spacing between spiral windings used to build the coil or strip 12 accommodates the tooling 30 used to machine the surfaces of the coil or strip 12. (Machining of free surfaces is following solidification of the layers). The size of the spacing between winds of the coil or strip 12 shown in FIGS. 2-4 is for illustrative purposes only and it is to be understood that the spacing could be larger or smaller than that shown depending upon the requirements of a given additive manufacturing and / or machining operation.WAAM Additive Manufacturing Process

[0053] FIGS. 5-7 illustrate an alternative additive manufacturing process that may be used to directly fabricate the coil or strip 12. FIG. 5 is a schematic of a method to fabricate first buildlayer of a chemical composition graded coil of metal alloy strip or sheet using wire arc additive manufacturing (WAAM) and machining processes. One of an arbitrary number of feed wires 40 are shown, and the substrate material is not shown. FIG. 6 depicts an intermediate stage in the fabrication of an arbitrary number of build layers. FIG. 7 depicts the final stage in the fabrication of an arbitrary number of build layers. Machining process is not shown in FIGS. 6-7.

[0054] Specifically, a wire arc additive manufacturing (WAAM) process is schematically illustrated for producing the coil or strip 12. The same principles and benefits apply here as described above in connection with the powder DED additive manufacturing process of FIGS. 2- 4 and are incorporated herein by reference. With WAAM, one or several feeds of wire 40 of select chemical composition are fed to a WAAM torch 42, which locally melts and deposits the metal along a spiral path to produce the coil or strip 12 layer-by-layer in similar fashion to that described for the powder DED process of FIGS. 2-4. The graded chemical composition of the coil or strip 12 is derived from the composition and feed of the wire 40. The same or similar machining process 30 may be employed as previously described. The coil or strip 12 thus produced is subsequently cold rolled and processed as described above for powder DED to make end products having controlled and geometrically varied chemical compositions that benefit the processes and / or end product.Cold-Rolling Fabrication By DED

[0055] FIGS. 9A-9C, 10A-10B, and 11A-11D show the fabricating, machining, and cold-rolling of two straight walls having post-DED dimensions of approximately 76 mm x 25 mm x 3 mm, and each containing 50% SS316L (powder 901) and 50% IN718 (powder 902) composition per FIG 9A. FIG. 9A shows powders 901-902 directed through nozzle 904 incident to laser beam 903 that locally melts the powders 901-902 at the incident region 905 and deposits the molten metal initially onto a solid build substrate 907 (build platform) to fabricate wall 906. FIG. 9Bshows the gradient transition from SS316L to IN718 in the volume % shown in plots 911-912, respectively for wall 906. FIG. 9C is an image of the process being performed.

[0056] SSI6L grade is the low carbon version of 316 stainless steel, and is sometimes referred to as A4 stainless steel or marine grade stainless steel. As the carbon content is significantly lower than standard SS316, this makes it less prone to sensitization (corrosion) during welding or high- temperature exposure. IN718 is a nickel -based Inconel superalloy, developed to resist most of all high temperatures, usually in cases until 70% of the absolute melting temperature. It has an excellent creep, corrosion and oxidation resistance as well as a good surface stability and fatigue life. IN718 known for its excellent corrosion resistance and ability to be welded without compromising its properties. For powders, a narrow size distribution can be utilized, such as between 15 pm to 45 pm for laser-based processes (and between and 45 pm to 105 pm for electron beam processes).

[0057] Other materials that can be used in the fabrication processes (powders and wires) include stainless steels, tool steels, carbon and low carbon steels, titanium alloys, nickel-base alloys, aluminum alloys, cobalt-based alloys, precious metal alloys, copper alloys, and cobalt-chromium alloy.

[0058] FIG. 10A shows these two walls after the DED fabrication, while FIG. 10B shows the walls after machining to ~1 mm thickness.

[0059] After the machined walls were removed from the substrate, they were cold-rolled on a laboratory-scale rolling mill, shown in images 1101-1102 in FIG. 11 A. FIG. 11B shows the two sample before cold rolling (before cold-rolling samples 1111-1112). FIG. 11B shows before coldrolling samples 1111-1112 after cold rolling (after cold-rolling samples 1121-1122, respectively).

[0060] FIG. 11D shows the a-d orientation in illustrations 1131-1132 of, respectively, the after cold-rolling samples 1121-1122 for the thickness data collected after 4 passes for the first sample #1 and 7 passes for the second sample. The thickness data collected is in TABLES I-II.TABLE I Thickness of First SampleTABLE II Thickness of Second Sample

[0061] From the data in TABLES I-II, thickness differences within each rolled sample were observed during successive passes through the mill (again, the first and second samples underwent four passes and seven passes, respectively). These “within-sample” thickness variations likely arose from the vastly different mechanical properties between SS316L and IN718, motivating further understanding and new modeling efforts to determine mill set-up parameters that would ensure desired quality outcomes and mill stability when actual coils are rolled, particularly at production level speeds (e.g., >10 m / s).

[0062] Following this laboratory-scale rolling, the samples underwent microstructure characterization. (FIG. 12) These embodiments — although for very small, straight-walled parts rather than coils of longer sheet, and also for DED with post-machining not integrated machining — represent the first known cold-rolling (not merely burnishing) of machined chemical - composition-graded (functionally graded) DED components.Fabrication of Hybrid-Manufactured Coils

[0063] Building on this, hybrid-manufactured coils as described and taught above can be fabricated. In-situ thermal data, post-build geometry measurements, residual stress, and microstructure characterizations obtained can be used to calibrate such hybrid manufacture. These can then be utilized for improved DED and machining parameters for the hybrid builds.Applications and Representative Products

[0064] Embodiments of the present invention provide an entirely new, transformative, scalable, and agile manufacturing process capable of producing novel, chemical -composition-graded cold- rolled metal strip and sheet that could then be used to deliver superior performing metal-sheet derived components across many diverse industries.

[0065] Examples of the many diverse end-use products that could be made from such chemicalcomposition-graded strip or sheet include tubes (structural and fluid-transport types), knives / blade edges, aircraft and propulsion components, marine vessel panels, battery current collector sheets, beverage cans, and numerous cladded products which could significantly benefit from eliminating the restriction of constant clad-layer thickness, as well as the restriction of “cladding” only through the thickness. In the case of commodity tube-stock, which is made by progressively forming cold rolled sheet, chemical-composition-grading suggests that the tube material could actually vary along its length, for instance from a stainless-steel alloy to a galvanized steel alloy, based on localized corrosion resistance needs vs. material cost.

[0066] Other tubes could vary from a copper alloy on the inside surface to a stainless-steel alloy on the outside surface, and with this “clad ratio” even varying along the tube length. Such novel capability is impossible with the conventional strip / sheet manufacturing process (it also is impractical to achieve using AM alone, z.e., without cold rolling, due to the extremely high sheet aspect ratios, and absence of required strain- hardening). The potential combinations for locationspecific alloy configurations is essentially unlimited, especially when combined with the flexibility of novel incremental sheet forming techniques.

[0067] Representative of these examples of products that may benefit from the inventive processes described above include:

[0068] Cookware / pans: The metal sheets used for cookware, including saucepans, frying pans, and saute pans can be tailored compositionally to exploit local (within-part) trade-offs between heat retention, formability, strength, corrosion resistance, and cost. The proposed methods can offer significantly greater flexibility in geometric material tailoring than conventional sheet cladding.

[0069] Knives / sharp edges: Since knife edge materials require high hardness to promote wear resistance, the proposed methods could be used to make knives and other sharp-edged / wear- resistant metal products in a way that only the sharp-edged region of the blade is composed of the high-hardness material, allowing flexibility to make the remaining part of the blade / component from other, less expensive strip material.

[0070] Aerospace / aircraft / hypersonic vehicle and propulsion system components: The composition of metal strip / sheet derived components used in aerospace / aircraft / hypersonic vehicles or propulsion system components could be customized to exploit the advantages of local (within-part) high-temperature resistance, strength, weight, corrosion resistance, etc., without the need for additional joining methods such as welding, riveting, bolting of dissimilar materials.

[0071] Ship / seaborne vessel hulls: The composition of metal strip / sheet used in the hulls and other components of ships or other seaborne vessels could be customized to exploit the advantages of local (within-part) corrosion resistance, strength, weight without the need for additional joining methods such as welding, riveting, bolting of dissimilar materials.

[0072] Battery current collectors: The metal sheets used as current collectors in battery cells can be tailored compositionally to exploit the advantages of local (within-part) electrical properties, corrosion resistance, and strength.

[0073] Beverage cans: The metal sheets used for beverage cans can tailored compositionally to exploit local (within-part) trade-offs between high formability, strength, and cost, based on the specific region of the part.

[0074] Cladded sheet products: The methods of the present invention offer a potentially far more flexible alternative to make cladded sheet metal products. In conventional sheet metal cladding, e.g., such as with stainless steel, copper, and aluminum for chef-quality cookware (pans), the cladded metals can each only have a single, uniform thickness. With the proposed methods, the “clad” thickness for different metals can be varied through the entire part as needed.

[0075] Those of ordinary skill in the art will appreciate that other features, modifications and advantages are possible in light of these teachings and are contemplated herein.

[0076] While embodiments of the invention have been shown and described, modifications thereof can be made by one skilled in the art without departing from the spirit and teachings of the invention. The embodiments described and the examples provided herein are exemplary only, and are not intended to be limiting. Many variations and modifications of the invention disclosed herein are possible and are within the scope of the invention. Accordingly, other embodiments are within the scope of the following claims. The scope of protection is not limited by the description set out above.

[0077] The disclosures of all patents, patent applications, and publications cited herein are hereby incorporated herein by reference in their entirety, to the extent that they provide exemplary, procedural, or other details supplementary to those set forth herein.

[0078] Amounts and other numerical data may be presented herein in a range format. It is to be understood that such range format is used merely for convenience and brevity and should be interpreted flexibly to include not only the numerical values explicitly recited as the limits of the range, but also to include all the individual numerical values or sub-ranges encompassed within that range as if each numerical value and sub-range is explicitly recited. For example, a numerical range of approximately 1 to approximately 4.5 should be interpreted to include not only the explicitly recited limits of 1 to approximately 4.5, but also to include individual numerals such as 2, 3, 4, and sub-ranges such as 1 to 3, 2 to 4, etc. The same principle applies to ranges reciting only one numerical value, such as “less than approximately 4.5,” which should be interpreted to include all of the above-recited values and ranges. Further, such an interpretation should apply regardless of the breadth of the range or the characteristic being described. The symbolis the same as “approximately”.

[0079] Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood to one of ordinary skill in the art to which the presently disclosed subject matter belongs. Although any methods, devices, and materials similar or equivalent to those described herein can be used in the practice or testing of the presently disclosed subject matter, representative methods, devices, and materials are now described.

[0080] Following long-standing patent law convention, the terms “a” and “an” mean “one or more” when used in this application, including the claims.

[0081] Unless otherwise indicated, all numbers expressing quantities of ingredients, reaction conditions, and so forth used in the specification are to be understood as being modified in allinstances by the term “about.” Accordingly, unless indicated to the contrary, the numerical parameters set forth in this specification are approximations that can vary depending upon the desired properties sought to be obtained by the presently disclosed subject matter.

[0082] As used herein, the term “and / or” when used in the context of a listing of entities, refers to the entities being present singly or in combination. Thus, for example, the phrase “A, B, C, and / or D” includes A, B, C, and D individually, but also includes any and all combinations and subcombinations of A, B, C, and D.

Claims

WHAT IS CLAIMED IS:

1. A method of making a metallic coil or strip precursor for a cold rolling operation, the method comprising: using additive manufacturing to directly fabricate a three-dimensional coil or strip in coil form having a predetermined length, thickness and width.

2. The method of Claim 1, wherein(a) the coil or strip has a graded composition and / or graded physical property and / or a graded metallurgical property in at least one dimension of the length and / or width and / or thickness of the coil or strip, and(b) the coil or strip is subsequently processed by cold rolling the coil or strip.

3. The method of Claim 2, wherein an end product is subsequently made from portions of the cold-rolled coil or strip and wherein the end product has geometric regions of different chemical composition.

4. The method of any of Claims 1-3, wherein the additive manufacturing process is powderbased directed energy deposition (DED).

5. The method of Claim 4, wherein the additive manufacturing process utilizes one or more powders selected from the group consisting of powders of stainless steel, tool steels, carbon and low carbon steels, titanium alloys, nickel-base alloys, aluminum alloys, cobalt-based alloys, precious metal alloys, copper alloys, and cobalt-chromium alloy.

6. The method of Claim 5, wherein(a) the additive manufacturing process utilizes at least two different types of powders of the one more powders; and(b) the ratio of the at least two different types of powders is varied during the additive manufacturing process.

7. The method of any of Claims 1-3, wherein the additive manufacturing process is wire arc additive manufacturing (WAAM).

8. The method of Claim 4, wherein the additive manufacturing process utilizes one or more wires selected from the gr7up consisting of wires of stainless steel, tool steels, carbon and low carbon steels, titanium alloys, nickel-base alloys, aluminum alloys, cobalt-based alloys, precious metal alloys, copper alloys, and cobalt-chromium alloy.

9. The method of Claim 8, wherein(a) the additive manufacturing process utilizes at least two different types of wires of the one more wires; and(b) the ratio of the at least two different types of wires is varied during the additive manufacturing process.

10. A method of making a metallic coil or strip by either a powder-based directed energy deposition (DED) or wire arc additive manufacturing (WAAM) process, wherein the coil or strip is direct printed along a spiral path layer-by-layer to build a three-dimensional coil or strip ofmetallic material having a coiled length, a thickness and a width, and wherein the metallic coil is subsequently cold rolled.

11. A method of making a product comprising:(a) making a metallic coil or strip by the method of Claim 10; and(b) utilizing the metallic coil or strip in a product selected from the group consisting of tubes, cookware, knives / blade edges, aircraft and propulsion components, marine vessel panels, battery current collector sheets, beverage cans, and cladded products.

12. A product made from a portion of at least one layer of additive manufactured and cold- rolled metallic sheet material, and wherein(a) the product has a predetermined geometric shape; and(b) the portion of metallic sheet material used in making the product has regions of different chemical compositions and / or different physical properties and / or different metallurgical properties derived from the additive manufacturing and cold rolling processes corresponding to different regions of the predetermined geographic shape of the product.

13. A method of making a product from cold-rolled metallic coil or strip material, comprising:(a) directly printing a coil or strip precursor using an additive manufacturing process without hot-rolling and having a graded chemical composition in at least one length, width or thickness dimension of the precursor coil or strip;(b) subsequently cold rolling the printed coil or strip; and(c) further processing the cold-rolled strip to form the product having at least two regions of different chemical composition resulting from the direct printing of the coil or strip precursor.

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