CA3128089A1 - Reduction and removal of process oxides on stainless steel - Google Patents
Reduction and removal of process oxides on stainless steel Download PDFInfo
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- CA3128089A1 CA3128089A1 CA3128089A CA3128089A CA3128089A1 CA 3128089 A1 CA3128089 A1 CA 3128089A1 CA 3128089 A CA3128089 A CA 3128089A CA 3128089 A CA3128089 A CA 3128089A CA 3128089 A1 CA3128089 A1 CA 3128089A1
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- stainless steel
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- 229910001220 stainless steel Inorganic materials 0.000 title claims abstract description 52
- 239000010935 stainless steel Substances 0.000 title claims abstract description 48
- 238000000034 method Methods 0.000 title claims description 19
- 230000008569 process Effects 0.000 title claims description 13
- 230000009467 reduction Effects 0.000 title description 4
- 238000000137 annealing Methods 0.000 claims abstract description 25
- 229910052761 rare earth metal Inorganic materials 0.000 claims abstract description 17
- 229910052723 transition metal Inorganic materials 0.000 claims abstract description 9
- 150000003624 transition metals Chemical class 0.000 claims abstract description 9
- 230000001680 brushing effect Effects 0.000 claims description 30
- 150000002910 rare earth metals Chemical class 0.000 claims description 7
- 150000003839 salts Chemical class 0.000 abstract description 11
- 238000005554 pickling Methods 0.000 abstract description 10
- 239000002253 acid Substances 0.000 abstract description 7
- 239000000463 material Substances 0.000 description 13
- 239000007864 aqueous solution Substances 0.000 description 8
- 239000000243 solution Substances 0.000 description 7
- QTBSBXVTEAMEQO-UHFFFAOYSA-M Acetate Chemical compound CC([O-])=O QTBSBXVTEAMEQO-UHFFFAOYSA-M 0.000 description 6
- 239000000725 suspension Substances 0.000 description 6
- 239000007900 aqueous suspension Substances 0.000 description 5
- 239000007788 liquid Substances 0.000 description 5
- 238000004519 manufacturing process Methods 0.000 description 5
- 239000002245 particle Substances 0.000 description 5
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 description 4
- 239000002105 nanoparticle Substances 0.000 description 4
- 238000005498 polishing Methods 0.000 description 4
- 229910001994 rare earth metal nitrate Inorganic materials 0.000 description 4
- -1 rare earth metal salt Chemical class 0.000 description 4
- HBMJWWWQQXIZIP-UHFFFAOYSA-N silicon carbide Chemical compound [Si+]#[C-] HBMJWWWQQXIZIP-UHFFFAOYSA-N 0.000 description 4
- 229910010271 silicon carbide Inorganic materials 0.000 description 4
- 239000004094 surface-active agent Substances 0.000 description 4
- 230000000007 visual effect Effects 0.000 description 4
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 3
- 229910000831 Steel Inorganic materials 0.000 description 3
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 3
- 230000008901 benefit Effects 0.000 description 3
- 229910052760 oxygen Inorganic materials 0.000 description 3
- 239000001301 oxygen Substances 0.000 description 3
- 239000010959 steel Substances 0.000 description 3
- 229910052727 yttrium Inorganic materials 0.000 description 3
- VWQVUPCCIRVNHF-UHFFFAOYSA-N yttrium atom Chemical compound [Y] VWQVUPCCIRVNHF-UHFFFAOYSA-N 0.000 description 3
- 229910052684 Cerium Inorganic materials 0.000 description 2
- 229910002651 NO3 Inorganic materials 0.000 description 2
- NHNBFGGVMKEFGY-UHFFFAOYSA-N Nitrate Chemical compound [O-][N+]([O-])=O NHNBFGGVMKEFGY-UHFFFAOYSA-N 0.000 description 2
- 150000007513 acids Chemical class 0.000 description 2
- 150000004649 carbonic acid derivatives Chemical class 0.000 description 2
- GWXLDORMOJMVQZ-UHFFFAOYSA-N cerium Chemical compound [Ce] GWXLDORMOJMVQZ-UHFFFAOYSA-N 0.000 description 2
- 150000003841 chloride salts Chemical class 0.000 description 2
- 238000004140 cleaning Methods 0.000 description 2
- 238000005097 cold rolling Methods 0.000 description 2
- 238000005260 corrosion Methods 0.000 description 2
- 230000007797 corrosion Effects 0.000 description 2
- 239000003599 detergent Substances 0.000 description 2
- 238000007598 dipping method Methods 0.000 description 2
- 238000005530 etching Methods 0.000 description 2
- 229910052746 lanthanum Inorganic materials 0.000 description 2
- FZLIPJUXYLNCLC-UHFFFAOYSA-N lanthanum atom Chemical compound [La] FZLIPJUXYLNCLC-UHFFFAOYSA-N 0.000 description 2
- 229910052751 metal Inorganic materials 0.000 description 2
- 239000002184 metal Substances 0.000 description 2
- 229910001404 rare earth metal oxide Inorganic materials 0.000 description 2
- 238000004611 spectroscopical analysis Methods 0.000 description 2
- 238000005507 spraying Methods 0.000 description 2
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 2
- 238000009736 wetting Methods 0.000 description 2
- RUDFQVOCFDJEEF-UHFFFAOYSA-N yttrium(III) oxide Inorganic materials [O-2].[O-2].[O-2].[Y+3].[Y+3] RUDFQVOCFDJEEF-UHFFFAOYSA-N 0.000 description 2
- 229910000975 Carbon steel Inorganic materials 0.000 description 1
- 239000004677 Nylon Substances 0.000 description 1
- QCWXUUIWCKQGHC-UHFFFAOYSA-N Zirconium Chemical compound [Zr] QCWXUUIWCKQGHC-UHFFFAOYSA-N 0.000 description 1
- HMDDXIMCDZRSNE-UHFFFAOYSA-N [C].[Si] Chemical compound [C].[Si] HMDDXIMCDZRSNE-UHFFFAOYSA-N 0.000 description 1
- 239000003082 abrasive agent Substances 0.000 description 1
- 230000009471 action Effects 0.000 description 1
- 239000012491 analyte Substances 0.000 description 1
- 239000012736 aqueous medium Substances 0.000 description 1
- 239000010962 carbon steel Substances 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 239000011248 coating agent Substances 0.000 description 1
- 238000000576 coating method Methods 0.000 description 1
- 238000010924 continuous production Methods 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- 239000008367 deionised water Substances 0.000 description 1
- 229910021641 deionized water Inorganic materials 0.000 description 1
- 238000004851 dishwashing Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 229910001651 emery Inorganic materials 0.000 description 1
- 239000000835 fiber Substances 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- 238000007689 inspection Methods 0.000 description 1
- 229910052742 iron Inorganic materials 0.000 description 1
- JEIPFZHSYJVQDO-UHFFFAOYSA-N iron(III) oxide Inorganic materials O=[Fe]O[Fe]=O JEIPFZHSYJVQDO-UHFFFAOYSA-N 0.000 description 1
- 229910000734 martensite Inorganic materials 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 239000002609 medium Substances 0.000 description 1
- 150000002823 nitrates Chemical class 0.000 description 1
- 229920001778 nylon Polymers 0.000 description 1
- TWNQGVIAIRXVLR-UHFFFAOYSA-N oxo(oxoalumanyloxy)alumane Chemical compound O=[Al]O[Al]=O TWNQGVIAIRXVLR-UHFFFAOYSA-N 0.000 description 1
- 239000003973 paint Substances 0.000 description 1
- 238000010422 painting Methods 0.000 description 1
- 238000002360 preparation method Methods 0.000 description 1
- 238000005096 rolling process Methods 0.000 description 1
- 238000001878 scanning electron micrograph Methods 0.000 description 1
- 238000005482 strain hardening Methods 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 239000002344 surface layer Substances 0.000 description 1
- 238000004381 surface treatment Methods 0.000 description 1
- 239000002699 waste material Substances 0.000 description 1
- 229910052726 zirconium Inorganic materials 0.000 description 1
Classifications
-
- B08B1/12—
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21B—ROLLING OF METAL
- B21B45/00—Devices for surface or other treatment of work, specially combined with or arranged in, or specially adapted for use in connection with, metal-rolling mills
- B21B45/04—Devices for surface or other treatment of work, specially combined with or arranged in, or specially adapted for use in connection with, metal-rolling mills for de-scaling, e.g. by brushing
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D3/00—Diffusion processes for extraction of non-metals; Furnaces therefor
- C21D3/02—Extraction of non-metals
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D6/00—Heat treatment of ferrous alloys
- C21D6/002—Heat treatment of ferrous alloys containing Cr
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D6/00—Heat treatment of ferrous alloys
- C21D6/004—Heat treatment of ferrous alloys containing Cr and Ni
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
- C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
- C21D8/0247—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the heat treatment
- C21D8/0273—Final recrystallisation annealing
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D9/00—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D9/00—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
- C21D9/52—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for wires; for strips ; for rods of unlimited length
-
- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C18/00—Chemical coating by decomposition of either liquid compounds or solutions of the coating forming compounds, without leaving reaction products of surface material in the coating; Contact plating
- C23C18/02—Chemical coating by decomposition of either liquid compounds or solutions of the coating forming compounds, without leaving reaction products of surface material in the coating; Contact plating by thermal decomposition
- C23C18/08—Chemical coating by decomposition of either liquid compounds or solutions of the coating forming compounds, without leaving reaction products of surface material in the coating; Contact plating by thermal decomposition characterised by the deposition of metallic material
-
- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C18/00—Chemical coating by decomposition of either liquid compounds or solutions of the coating forming compounds, without leaving reaction products of surface material in the coating; Contact plating
- C23C18/02—Chemical coating by decomposition of either liquid compounds or solutions of the coating forming compounds, without leaving reaction products of surface material in the coating; Contact plating by thermal decomposition
- C23C18/12—Chemical coating by decomposition of either liquid compounds or solutions of the coating forming compounds, without leaving reaction products of surface material in the coating; Contact plating by thermal decomposition characterised by the deposition of inorganic material other than metallic material
- C23C18/1204—Chemical coating by decomposition of either liquid compounds or solutions of the coating forming compounds, without leaving reaction products of surface material in the coating; Contact plating by thermal decomposition characterised by the deposition of inorganic material other than metallic material inorganic material, e.g. non-oxide and non-metallic such as sulfides, nitrides based compounds
- C23C18/1208—Oxides, e.g. ceramics
- C23C18/1216—Metal oxides
-
- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C30/00—Coating with metallic material characterised only by the composition of the metallic material, i.e. not characterised by the coating process
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21B—ROLLING OF METAL
- B21B3/00—Rolling materials of special alloys so far as the composition of the alloy requires or permits special rolling methods or sequences ; Rolling of aluminium, copper, zinc or other non-ferrous metals
- B21B3/02—Rolling special iron alloys, e.g. stainless steel
Abstract
Oxides formed during annealing of stainless steel strip are removed with abrasive brushes, in lieu of acid or molten salt based pickling. In some embodiments, the stainless steel strip is treated with a rare earth element or a related transition metal before annealing, and then brushed after annealing to remove any oxides. The selection of brushes can impart a finished appearance to conventionally polished stainless steel.
Description
REDUCTION AND REMOVAL OF PROCESS OXIDES
ON STAINLESS STEEL
LeRoy R. Price Frederick A. Myers PRIORITY
[0001] This application claims priority to U.S. Provisional Application Serial No. 62/808,399, filed February 21, 2019, entitled "Reduction and Removal of Process Oxides on Stainless Steel," the disclosure of which is incorporated by reference herein.
BACKGROUND
ON STAINLESS STEEL
LeRoy R. Price Frederick A. Myers PRIORITY
[0001] This application claims priority to U.S. Provisional Application Serial No. 62/808,399, filed February 21, 2019, entitled "Reduction and Removal of Process Oxides on Stainless Steel," the disclosure of which is incorporated by reference herein.
BACKGROUND
[0002] The present application relates to mechanical removal of oxides formed during the processing of stainless steels.
[0003] During typical stainless steel strip processing, oxides are generated during high temperature anneal cycles used to soften the steel after cold rolling. Typically these oxides are removed prior to subsequent processing by employing conventional acid-based pickling techniques.
Such descaling processes employ exposing the annealed stainless steel strip to a molten salt bath and/or one or more acids in an acid bath.
Descaling is slow, costly, and can be environmentally challenging.
SUMMARY
Such descaling processes employ exposing the annealed stainless steel strip to a molten salt bath and/or one or more acids in an acid bath.
Descaling is slow, costly, and can be environmentally challenging.
SUMMARY
[0004] In the present embodiments, it has been determined that the oxides formed during annealing can be removed with abrasive brushes. In some embodiments, the stainless steel strip is treated with a rare earth element or a related transition metal before annealing, and then brushed after annealing to remove any oxides. The brushing operation imparts a surface texture to the material that may eliminate the need for more conventional polishing and finishing practices.
DESCRIPTION OF DRAWINGS
DESCRIPTION OF DRAWINGS
[0005] Fig. 1 depicts the GDS depth profile for a 436L stainless steel sample after final anneal with no brushing.
[0006] Fig. 2 depicts the GDS depth profile for a 436L stainless steel sample after final anneal with one pass brushing.
[0007] Fig. 3 depicts the GDS depth profile for a 436L stainless steel sample after final anneal with two pass brushing.
[0008] Fig. 4 depicts the GDS depth profile for a 436L stainless steel sample after final anneal with three pass brushing.
[0009] Fig. 5 depicts the GDS depth profile for a 436L stainless steel sample after final anneal without any rare earth metal or rare metal treatment and no brushing.
[0010] Fig. 6 depicts the GDS depth profile for a 436L stainless steel sample after final anneal with Minimox treatment but no brushing.
[0011] Fig. 7 depicts an SEM image of a 436L stainless steel surface after final anneal/pickling showing grain pattern.
[0012] Fig. 8 depicts Chromeshield 22 stainless steel cold-rolled samples after annealing, with the Minimox dipped samples on the right.
[0013] Fig. 9a and 9b depict the GDS depth profiles for untreated and treated panels.
[0014] Fig. 10 depicts the annealed Chromeshield 22 stainless steel samples after Scotch-Brite brushing.
[0015] Fig. 11 depicts the annealed Chromeshield 22 stainless steel samples after bristle type brushing.
DETAILED DESCRIPTION
DETAILED DESCRIPTION
[0016] Annealing and pickling ("AP") practices are commonly used in stainless steel processing. Annealing is necessary to soften the steel after the work hardening induced during rolling. Annealing is usually conducted in air-based atmospheres at temperatures of 1700-2000 F
for several minutes. The resulting oxides that are formed are then removed by a pickling step. The pickling reactions are typically the rate controlling step during AP. Most stainless steel is sold in this "fully annealed" condition with the annealing oxide removed. If the pickling step can be eliminated, not only are the acids and molten salts used in descaling no longer be required, but the line speeds may be able to be increased.
for several minutes. The resulting oxides that are formed are then removed by a pickling step. The pickling reactions are typically the rate controlling step during AP. Most stainless steel is sold in this "fully annealed" condition with the annealing oxide removed. If the pickling step can be eliminated, not only are the acids and molten salts used in descaling no longer be required, but the line speeds may be able to be increased.
[0017] In some embodiments, mechanical brushing can be used to remove the oxides formed during annealing. Typically, the oxides formed after annealing are relatively thin (< 1 micron) and modern brushing machines have been found to be capable of removing this surface layer.
[0018] In other embodiments, the effectiveness of the brushing may be enhanced if the stainless steel strip is treated with a rare earth metal or a related transition metal before annealing. This surface treatment affects the growth of oxides on stainless steels, decreasing their thickness and altering the surface chemistry to make them easier to remove.
[0019] The manufacturing of stainless steel strips is well-known. The present oxide removal processes (also known as descaling) can be implemented in a standard stainless steel manufacturing process, replacing only the acid-based pickling and/or molten salt portion of the process.
[0020] Brushing machines, and the brushes used with them, are also well-known. Brushing is often used to impart a desired surface finish to a clean (or bright) stainless steel strip, i.e., to a strip from which any oxides have been previously removed.
[0021] In certain embodiments of the present process, such brushing machines are used to brush oxide-bearing stainless steel strip, thereby removing the oxides from the surface of the stainless steel strip. In one embodiment, the brushing machines use ScotchBriteTM nonwoven type rolls that contain a loose web of nylon or other fibers impregnated with alumina or silicon carbide type particles. Typical roll types would include the 3M CB Cleaning rolls and the CS-CB Clean and Strip rolls Scotch-Brite is an abrasive material sold by the 3M Company, St. Paul, Minnesota.
[0022] The rare earth element or related transition metal can be applied to stainless steel strip in a liquid form, such as an aqueous suspension or an aqueous solution comprising metal salts. The rare earth element can include yttrium, cerium, lanthanum, and their associated oxides or nitrates. And the related transition metal can include zirconium and its associated oxides.
[0023] The liquid containing rare earth metal or related transition metal can be applied to a stainless steel surface prior to annealing by dipping, painting, and spraying and then dried.
[0024] In some embodiments, the rare earth element can be provided in a suspension. For example, Minimox liquid, available from Materials Interface, Inc. of Sussex, Wisconsin, comprises nano-particles of rare earth oxide in suspension. Such materials are also described in U.S.
Patent No. 8,568,538, the disclosure of which is incorporated by reference herein. It is believed that Minimox contains up to about I%
by weight yttrium as Y203 nanoparticles that are suspended in an aqueous medium.
Patent No. 8,568,538, the disclosure of which is incorporated by reference herein. It is believed that Minimox contains up to about I%
by weight yttrium as Y203 nanoparticles that are suspended in an aqueous medium.
[0025] An embodiment of the present invention comprises an aqueous solution of rare earth metal salt. The salt can be a nitrate or an acetate, for example. The rare earth metal salt can include one or more of cerium (Ce), lanthanum (La), and yttrium (Y). Chlorides can permit corrosion and carbonates may not soluble, thus, in the present application rare earth metal salts do not include carbonates or chlorides.
[0026] Rare earth metal salts are well known in the industry and commercially available. It is not necessary that the nitrate or acetate be of any particular grain size, and particularly there is no need for the salts, or the resulting rare earth metal oxides, to be limited to nanoparticles, which are considered to be particles with dimensions in the range of 1 to 100 nm.
[0027] The solution comprises rare earth metal nitrate or acetate dissolved in water, preferably deionized water. The concentration of the rare earth metal nitrate or acetate in the aqueous solution can extend to the limits of solubility of the particular salt. In certain embodiments, a solution can have a concentration equal to about 1 to about 10 g of rare earth metal nitrate or acetate to about 200 g of total aqueous solution. In other embodiments, a solution can have a concentration equal to about 1 to about 20 g of rare earth metal nitrate or acetate to about 200 g of total aqueous solution.
[0028] In some embodiments, the amount of the rare earth metal or related transition metal that is applied to the stainless steel surface has a density of about 300 to 3000 pg/m2, or in some embodiments a density of about 500 ¨ 8000 pg/m2 or in other embodiments 5000-8000 pg/m2.
[0029] To improve wetting of the stainless steel, a surfactant may be added to the aqueous solution or suspension. Surfactants are added to a concentration of about 0.1% to 5% by weight of solution, and in some embodiments, in a concentration of about 0.1% to 0.5% by weight of solution. Any surfactant known to enhance wetting of an aqueous solution or suspension onto a stainless steel surface can be used. The surfactant may comprise a detergent, such as dishwashing detergent.
[0030] The resulting aqueous solution or suspension can be applied to one or both surfaces -of a stainless steel strip (or to any other stainless steel product) by any method known to evenly apply liquids to a surface, including brushing, sponging, roll coating, spraying, and dipping. It is then dried using any method currently used to dry paints and other liquids on moving strip or webs such as forced air, infrared heating, convection ovens, etc.
[0031] It is believed the present invention benefits all types of stainless steel.
The stainless steels that benefit from the present invention include ferritic, austenitic, and martensitic stainless steels.
The stainless steels that benefit from the present invention include ferritic, austenitic, and martensitic stainless steels.
[0032] To use the methods of the present invention, stainless steel strip is manufactured using conventional, well-known practices, except as follows. After annealing, rather than pickling/molten salt descaling, the stainless steel strip is brushed on one or both sides at least once. If rare earth metals or related transition metal solutions or suspensions are to be applied to the strip, they are applied to one or both sides of the stainless steel strip prior to annealing. If the stainless steel manufacturing process is a continuous process, the solution or suspension is applied in-line by methods known in the art, and the brushing is likewise done in-line. Alternatively, either or both processes can be performed as batch operations, or off-line, as well.
[0033] Example 1
[0034] Two 436L stainless coils provided by AK Steel Corporation, West Chester, Ohio, were each partially coated with Minimox nano-yttrium oxide rare earth based suspension and then annealed. In each case, along the length of the strip, approximately one-half was coated and one-half was not coated. Annealing was conducted in air with 3%
excess oxygen at approximately 1950F/1066C. Line speed was 45 ft/min and time in the furnace was about 3.5 min.
excess oxygen at approximately 1950F/1066C. Line speed was 45 ft/min and time in the furnace was about 3.5 min.
[0035] After annealing, there was noted only a slight color difference on the surface of the strip between the coated portion of each coil and the uncoated portion. However, there was a more noticeable difference in the appearance on the sidewalls of each coil.
[0036] The scale on either the treated or untreated portion of the strip was easily removed by abrading the steel strip with an ultra-smooth, #400 grit alumina or silicon carbide abrasive paper.
[0037] Example 2
[0038] The stainless steel coils of Example 1 were brushed using two conventional brush stands having 3M Scotch-Brite nonwoven brushes typically used to remove red rust from carbon steel. There were two brush types. There were two brushes in tandem that contacted the top of the strip ("Maroon" medium aggressive Type CB cleaning brushes with aluminum oxide abrasive media particles) and two that contacted the bottom ("Black" heavy duty Type CS-CB Clean and Strip brushes with more aggressive silicon carbide abrasive media particles). Note that the brushes were not new but recently dressed and balanced.
Brush speed was 250-300 surface ft/min and line speed was 45 ft/min.
Work pressure was in the range of 0.1 to 0.5 horsepower per inch of working width.
Brush speed was 250-300 surface ft/min and line speed was 45 ft/min.
Work pressure was in the range of 0.1 to 0.5 horsepower per inch of working width.
[0039] After one pass through the brushing station, removal of the oxide on the top side was less than the removal on the bottom side due to the use of the more aggressive brushes on the bottom. The top was "dark" in appearance and the bottom "bright" indicating more residual oxide on the top and little remaining oxide on the bottom. There was also a noticeable linear pattern on the strip due to contact with the rolls. No visual differences were detected between the Minimox-treated and non-treated portions of the strip.
[0040] The strip was then passed through the line a second time.
Removal was marginally more noticeable on the top side but the "dark"
appearance was still present. Oxide removal was visually complete on the bottom side and the texture was smoother than after one pass.
Again no visual difference was detected between the Minimox treated and non-Minimox treated portions.
Removal was marginally more noticeable on the top side but the "dark"
appearance was still present. Oxide removal was visually complete on the bottom side and the texture was smoother than after one pass.
Again no visual difference was detected between the Minimox treated and non-Minimox treated portions.
[0041] The strip was then reversed so that the previous bottom side was now subjected to the less aggressive top side roll brushes and the previous top side with the more aggressive roll brushes. At this point the new top surface not only had a "bright" appearance but also had a smoother texture similar to standard #4 Polish stainless. #4 Polish is the preferred short line grit pattern directional finish for stainless steel that is typically used for appliance and food preparation surfaces and equipment. #4 Polish is a standard surface finish created by polishing with a 150 grit emery polishing belts as described in the Stainless Steel Comparator published by AK Steel Corporation, West Chester, Ohio.
The bottom surface was also bright after this third pass. Therefore brushing operation can replace the expensive separate stainless steel process step of surface polishing to obtain the desired appearance on the finished product.
The bottom surface was also bright after this third pass. Therefore brushing operation can replace the expensive separate stainless steel process step of surface polishing to obtain the desired appearance on the finished product.
[0042] The visual appearance observations of the strip was supplemented by Glow Discharge Spectroscopy (GDS) measurement to verify removal of the oxide (Figures 1-4). The oxygen peak (0) moves closer to the surface (0 Depth location) as the number of brushing passes increases.
Note that in production, it may not be economical to run material through the line multiple times. Instead the number of brushes that would be used on a given process line would increase. For instance in the current study, two brushes per side were used. If two passes are needed to remove the oxide, then the production equivalent would be four brushes per side. If three passes are needed on a two brush line, then six brushes per side would be used.
Note that in production, it may not be economical to run material through the line multiple times. Instead the number of brushes that would be used on a given process line would increase. For instance in the current study, two brushes per side were used. If two passes are needed to remove the oxide, then the production equivalent would be four brushes per side. If three passes are needed on a two brush line, then six brushes per side would be used.
[0043] The effect of the Minimox rare earth treatment was to reduce the thickness of the oxide that was grown during annealing. Thinner oxides require less removal and therefore less brushing. A comparison of the GDS results for material from the same coil annealed with and without oxide is shown in Figures 5 and 6. A measure of the relative thickness of the oxide is where the iron (Fe2) curve reaches the 50%
Analyte Weight Percent point. In the case, the value of approximately 0.25 micron for the no treatment case vs 0.175 micron for the Minimox treated material would suggest a 30% reduction in oxide thickness.
This would translate into a 30% faster process speed or 30% better life on a given set of rolls before dressing is needed. Note that 30% less removal would occur indicating less waste disposal.
Analyte Weight Percent point. In the case, the value of approximately 0.25 micron for the no treatment case vs 0.175 micron for the Minimox treated material would suggest a 30% reduction in oxide thickness.
This would translate into a 30% faster process speed or 30% better life on a given set of rolls before dressing is needed. Note that 30% less removal would occur indicating less waste disposal.
[0044] Two additional advantages may be associated with brushing versus molten salt/pickling after final anneal. First, the brushing operation leaves a surface pattern from the abrasive action of the brushes. The final brushing type and operation can be selected to impart a preferred finish appearance to the material. The surface of molten salt/acid pickled material does not have a discernable pattern when viewed
[0045] Second, on a microscopic level, material that has been pickled has a pattern that is associated with the preferred etching of grain boundaries (Figure 7). Although not visible, this pattern can result in poorer corrosion performance for the material. Since chemicals are not used in brushing, there is no etching of grain boundaries.
[0046] Example 3
[0047] Cold rolled samples of Chromeshield 22 stainless steel strip provided by AK Steel Corporation, West Chester, Ohio, were annealed in air at 1875 F (1024 C) for 3.5 minutes to simulate strip anneal after cold rolling. The samples were alkaline cleaned prior to annealing and two were subsequently dip treated with Minimox 721 yttria nano particle 1% aqueous suspension for 5 seconds at room temperature and allowed to air dry. Visual differences between the treated and untreated sample were apparent after annealing. See Fig. 8.
[0048] The surfaces were examined via a depth profile using glow discharge spectroscopy (GDS). Results are shown for the untreated panels (See Fig. 9a) and the treated panels (See Fig. 9b). In both cases, the oxide region appeared to be less than 0.5 micron thick. Profiles for the treated samples may have been affected by non-uniform application of the Minimox suspension.
[0049] Samples were then brushed on one side with a Scotch-Brite roll using a laboratory brush unit with alumina particle impregnated rolls.
Inspection indicated that the oxide was essentially removed after approximately four passes through the brush.
Inspection indicated that the oxide was essentially removed after approximately four passes through the brush.
[0050] The two samples were also brushed on the opposite side using a silicon carbon impregnated bristle brush. In this case, removal of the oxide was not as complete and the surface was less uniform with visible lines.
[0051] The material brushed with Scotch-Brite rolls is shown in Fig.
10. The material brushed with the bristle brush is shown in Fig. 11.
10. The material brushed with the bristle brush is shown in Fig. 11.
[0052] Example 4
[0053] A 436L stainless strip is processed as follows at 45 ft/min after 3.5 minute anneal in a 3% excess oxygen air oven at 1950 F:
[0054] The anneal oxide is removed from the stainless surface by subjecting the strip to between 2-4 3M Scotch- Brite silicon carbide impregnated brushes
[0055] A smoother surface is obtained by subsequently passing the material through 1-2 less aggressive 3M Scotch-Brite alumina impregnated brushes.
[0056] First brushing with an aggressive brush followed by a less aggressive brush results in a more uniform surface texture than using only aggressive brushes.
[0057] Higher line speeds require more brushing stations and/or more aggressive brushes.
Claims (3)
1. A process for removing oxides from annealed stainless steel comprising the steps of a. Providing a stainless steel strip having at least one surface, b. Annealing said stainless steel strip, c. Removing oxides formed during said annealing step by brushing said at least one surface.
2. The process of claim 1 further comprising the step of applying a rare earth metal or related transition metal to said at least one surface before the annealing step.
3. The process of claim 1 further comprising the step of employing a finishing roll after the brushing operation that imparts an appearance similar to polished stainless steel.
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US201962808399P | 2019-02-21 | 2019-02-21 | |
US62/808,399 | 2019-02-21 | ||
PCT/US2020/019266 WO2020172554A1 (en) | 2019-02-21 | 2020-02-21 | Reduction and removal of process oxides on stainless steel |
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CA3128089A1 true CA3128089A1 (en) | 2020-08-27 |
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CA3128089A Pending CA3128089A1 (en) | 2019-02-21 | 2020-02-21 | Reduction and removal of process oxides on stainless steel |
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US (1) | US20200270719A1 (en) |
EP (1) | EP3927474A1 (en) |
JP (1) | JP2022521736A (en) |
KR (1) | KR20210130188A (en) |
CA (1) | CA3128089A1 (en) |
MX (1) | MX2021010126A (en) |
WO (1) | WO2020172554A1 (en) |
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Publication number | Priority date | Publication date | Assignee | Title |
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US3873280A (en) * | 1972-08-22 | 1975-03-25 | Merit Abrasive Prod | Descaling of steel strip |
JP2613317B2 (en) * | 1990-04-20 | 1997-05-28 | 川崎製鉄株式会社 | Annealing and descaling of stainless steel strip |
JPH0525666A (en) * | 1991-07-22 | 1993-02-02 | Kawasaki Steel Corp | Manufacture of austenitic stainless steel strip |
AU5904098A (en) * | 1996-12-26 | 1998-07-31 | J&L Speciality Steel, Inc. | Brushing process for corrosion and oxidation resistance |
TW504520B (en) * | 1997-03-27 | 2002-10-01 | Kawasaki Steel Co | Chromium-containing hot rolled steel strip and its production method |
US6088895A (en) * | 1999-01-21 | 2000-07-18 | Armco Inc. | Method for descaling hot rolled strip |
US8197613B2 (en) * | 2005-06-14 | 2012-06-12 | Material Interface, Inc. | Nanoparticle surface treatment |
JP5283156B2 (en) * | 2008-03-18 | 2013-09-04 | 日新製鋼株式会社 | Oxidation scale removal method and oxidation scale removal apparatus for stainless cold rolled steel strip |
CA3040895C (en) * | 2016-10-19 | 2021-11-16 | Ak Steel Properties, Inc. | Surface modification of stainless steels |
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2020
- 2020-02-21 KR KR1020217030142A patent/KR20210130188A/en not_active Application Discontinuation
- 2020-02-21 MX MX2021010126A patent/MX2021010126A/en unknown
- 2020-02-21 JP JP2021548654A patent/JP2022521736A/en active Pending
- 2020-02-21 EP EP20716982.2A patent/EP3927474A1/en not_active Withdrawn
- 2020-02-21 CA CA3128089A patent/CA3128089A1/en active Pending
- 2020-02-21 US US16/797,635 patent/US20200270719A1/en not_active Abandoned
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MX2021010126A (en) | 2021-09-23 |
US20200270719A1 (en) | 2020-08-27 |
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