US20230279534A1 - Metal coated steel strip - Google Patents
Metal coated steel strip Download PDFInfo
- Publication number
- US20230279534A1 US20230279534A1 US18/172,476 US202318172476A US2023279534A1 US 20230279534 A1 US20230279534 A1 US 20230279534A1 US 202318172476 A US202318172476 A US 202318172476A US 2023279534 A1 US2023279534 A1 US 2023279534A1
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- alloy
- coating
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- coated
- metal strip
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- 229910052751 metal Inorganic materials 0.000 title claims description 18
- 239000002184 metal Substances 0.000 title claims description 18
- 229910000831 Steel Inorganic materials 0.000 title abstract description 22
- 239000010959 steel Substances 0.000 title abstract description 22
- 238000000576 coating method Methods 0.000 claims abstract description 65
- 239000011248 coating agent Substances 0.000 claims abstract description 60
- 229910052749 magnesium Inorganic materials 0.000 claims abstract description 17
- 229910052720 vanadium Inorganic materials 0.000 claims abstract description 13
- 229910000676 Si alloy Inorganic materials 0.000 claims abstract description 11
- 229910045601 alloy Inorganic materials 0.000 claims description 54
- 239000000956 alloy Substances 0.000 claims description 54
- 229910007981 Si-Mg Inorganic materials 0.000 claims description 16
- 229910008316 Si—Mg Inorganic materials 0.000 claims description 16
- 229910052710 silicon Inorganic materials 0.000 claims description 13
- 229910052725 zinc Inorganic materials 0.000 claims description 12
- 229910052782 aluminium Inorganic materials 0.000 claims description 11
- 238000007792 addition Methods 0.000 claims description 7
- 239000012535 impurity Substances 0.000 claims description 3
- 239000002356 single layer Substances 0.000 claims description 2
- 238000005260 corrosion Methods 0.000 description 20
- 230000007797 corrosion Effects 0.000 description 20
- 239000011777 magnesium Substances 0.000 description 18
- 239000011701 zinc Substances 0.000 description 12
- 239000000047 product Substances 0.000 description 11
- 229910001092 metal group alloy Inorganic materials 0.000 description 10
- 239000003973 paint Substances 0.000 description 8
- 239000007789 gas Substances 0.000 description 7
- FYYHWMGAXLPEAU-UHFFFAOYSA-N Magnesium Chemical compound [Mg] FYYHWMGAXLPEAU-UHFFFAOYSA-N 0.000 description 6
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 5
- 239000010703 silicon Substances 0.000 description 5
- HCHKCACWOHOZIP-UHFFFAOYSA-N Zinc Chemical compound [Zn] HCHKCACWOHOZIP-UHFFFAOYSA-N 0.000 description 4
- 239000004411 aluminium Substances 0.000 description 4
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 4
- 239000008199 coating composition Substances 0.000 description 4
- 238000001816 cooling Methods 0.000 description 4
- 238000010438 heat treatment Methods 0.000 description 4
- XEEYBQQBJWHFJM-UHFFFAOYSA-N iron Substances [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 3
- 239000010410 layer Substances 0.000 description 3
- 238000000034 method Methods 0.000 description 3
- 239000000203 mixture Substances 0.000 description 3
- 238000005096 rolling process Methods 0.000 description 3
- 229910006776 Si—Zn Inorganic materials 0.000 description 2
- FAPWRFPIFSIZLT-UHFFFAOYSA-M Sodium chloride Chemical compound [Na+].[Cl-] FAPWRFPIFSIZLT-UHFFFAOYSA-M 0.000 description 2
- 238000005275 alloying Methods 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 2
- 239000007795 chemical reaction product Substances 0.000 description 2
- 230000001143 conditioned effect Effects 0.000 description 2
- 238000003618 dip coating Methods 0.000 description 2
- 229910052742 iron Inorganic materials 0.000 description 2
- 230000001590 oxidative effect Effects 0.000 description 2
- 239000011856 silicon-based particle Substances 0.000 description 2
- 210000004894 snout Anatomy 0.000 description 2
- LEONUFNNVUYDNQ-UHFFFAOYSA-N vanadium atom Chemical compound [V] LEONUFNNVUYDNQ-UHFFFAOYSA-N 0.000 description 2
- 239000002253 acid Substances 0.000 description 1
- 238000003916 acid precipitation Methods 0.000 description 1
- 230000002378 acidificating effect Effects 0.000 description 1
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 229910052791 calcium Inorganic materials 0.000 description 1
- 229910052804 chromium Inorganic materials 0.000 description 1
- 238000004140 cleaning Methods 0.000 description 1
- 239000010960 cold rolled steel Substances 0.000 description 1
- 230000000295 complement effect Effects 0.000 description 1
- 238000010924 continuous production Methods 0.000 description 1
- 238000004090 dissolution Methods 0.000 description 1
- VBMVTYDPPZVILR-UHFFFAOYSA-N iron(2+);oxygen(2-) Chemical group [O-2].[Fe+2] VBMVTYDPPZVILR-UHFFFAOYSA-N 0.000 description 1
- JEIPFZHSYJVQDO-UHFFFAOYSA-N iron(III) oxide Inorganic materials O=[Fe]O[Fe]=O JEIPFZHSYJVQDO-UHFFFAOYSA-N 0.000 description 1
- 229910052748 manganese Inorganic materials 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 230000007935 neutral effect Effects 0.000 description 1
- 239000003921 oil Substances 0.000 description 1
- 239000001301 oxygen Substances 0.000 description 1
- 229910052760 oxygen Inorganic materials 0.000 description 1
- 239000002244 precipitate Substances 0.000 description 1
- 229910002059 quaternary alloy Inorganic materials 0.000 description 1
- 150000003839 salts Chemical class 0.000 description 1
- 239000011780 sodium chloride Substances 0.000 description 1
- 238000007711 solidification Methods 0.000 description 1
- 230000008023 solidification Effects 0.000 description 1
- 238000010186 staining Methods 0.000 description 1
- 229910052712 strontium Inorganic materials 0.000 description 1
- 239000000758 substrate Substances 0.000 description 1
Images
Classifications
-
- 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
- C23C2/00—Hot-dipping or immersion processes for applying the coating material in the molten state without affecting the shape; Apparatus therefor
- C23C2/04—Hot-dipping or immersion processes for applying the coating material in the molten state without affecting the shape; Apparatus therefor characterised by the coating 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
- C23C2/00—Hot-dipping or immersion processes for applying the coating material in the molten state without affecting the shape; Apparatus therefor
- C23C2/04—Hot-dipping or immersion processes for applying the coating material in the molten state without affecting the shape; Apparatus therefor characterised by the coating material
- C23C2/06—Zinc or cadmium or alloys based thereon
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C21/00—Alloys based on aluminium
- C22C21/10—Alloys based on aluminium with zinc as the next major constituent
-
- 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
- C23C2/00—Hot-dipping or immersion processes for applying the coating material in the molten state without affecting the shape; Apparatus therefor
- C23C2/04—Hot-dipping or immersion processes for applying the coating material in the molten state without affecting the shape; Apparatus therefor characterised by the coating material
- C23C2/12—Aluminium or alloys based thereon
-
- 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
- C23C2/00—Hot-dipping or immersion processes for applying the coating material in the molten state without affecting the shape; Apparatus therefor
- C23C2/34—Hot-dipping or immersion processes for applying the coating material in the molten state without affecting the shape; Apparatus therefor characterised by the shape of the material to be treated
- C23C2/36—Elongated material
- C23C2/40—Plates; Strips
-
- 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
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
- Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
- Y10T428/00—Stock material or miscellaneous articles
- Y10T428/12—All metal or with adjacent metals
- Y10T428/12493—Composite; i.e., plural, adjacent, spatially distinct metal components [e.g., layers, joint, etc.]
- Y10T428/12736—Al-base component
Definitions
- the present invention relates to strip, typically steel strip, which has a corrosion-resistant metal alloy coating of an alloy that contains aluminium, zinc, and silicon and is hereinafter referred to as an “Al—Zn—Si alloy” on this basis.
- the present invention relates particularly but not exclusively to a corrosion-resistant metal alloy coating that contains aluminium, zinc, silicon, and magnesium as the main elements in the alloy coating and is hereinafter referred to as an “Al—Zn—Si—Mg alloy” on this basis.
- the alloy coating may contain other elements that are present as deliberate alloying additions or as unavoidable impurities.
- the present invention relates particularly but not exclusively to steel strip that is coated with the above-described Al—Zn—Si—Mg alloy and can be cold formed (e.g. by roll forming) into an end-use product, such as roofing products.
- the Al—Zn—Si—Mg alloy of the present invention comprises the following ranges in % by weight of the elements Al, Zn, Si, and Mg:
- the Al—Zn—Si—Mg alloy of the present invention comprises the following ranges in % by weight of the elements Al, Zn, Si, and Mg:
- the metal-coated strip may be painted, for example with a polymeric paint, on one or both surfaces of the strip.
- the metal-coated strip may be sold as an end product itself or may have a paint coating applied to one or both surfaces and be sold as a painted end product.
- the present invention relates particularly but not exclusively to steel strip that is coated with the above-described Al—Zn—Si—Mg alloy and is optionally coated with a paint and thereafter is cold formed (e.g. by roll forming) into an end-use product, such as building products (e.g. profiled wall and roofing sheets).
- end-use product such as building products (e.g. profiled wall and roofing sheets).
- the present invention relates particularly but not exclusively to a cold formed (e.g. roll formed) end-use product (e.g. profiled wall and roofing sheet) comprising steel strip that is coated with the above-described Al—Zn—Si—Mg alloy and is optionally coated with a paint.
- a cold formed (e.g. roll formed) end-use product e.g. profiled wall and roofing sheet
- end-use product e.g. profiled wall and roofing sheet
- the corrosion-resistant metal alloy coating is formed on steel strip by a hot dip coating method.
- steel strip In the conventional hot-dip metal coating method, steel strip generally passes through one or more heat treatment furnaces and thereafter into and through a bath of molten metal alloy held in a coating pot.
- the metal alloy is usually maintained molten in the coating pot by the use of heating inductors.
- the strip usually exits the heat treatment furnaces via an outlet end section in the form of an elongated furnace exit chute or snout that dips into the bath. Within the bath the strip passes around one or more sink rolls and is taken upwardly out of the bath and is coated with the metal alloy as it passes through the bath.
- the metal alloy coated strip After leaving the coating bath the metal alloy coated strip passes through a coating thickness control station, such as a gas knife or gas wiping station, at which its coated surfaces are subjected to jets of wiping gas to control the thickness of the coating.
- a coating thickness control station such as a gas knife or gas wiping station
- the metal alloy coated strip then passes through a cooling section and is subjected to forced cooling.
- the cooled metal alloy coated strip may thereafter be optionally conditioned by passing the coated strip successively through a skin pass rolling section (also known as a temper rolling section) and a tension levelling section.
- the conditioned strip is coiled at a coiling station.
- the aluminium and zinc are provided in an Al—Zn—Si alloy coating on a steel strip for corrosion resistance.
- the aluminium, zinc, and magnesium are provided in an Al—Zn—Si alloy coating on a steel strip for corrosion resistance.
- the silicon is provided in both alloy types to prevent excessive alloying between a steel strip and the molten coating in the hot-dip coating method.
- a portion of the silicon takes part in a quaternary alloy layer formation but the majority of the silicon precipitates as needle-like, pure silicon particles during solidification. These needle-like silicon particles are also present in the inter-dendritic regions of the coating.
- One corrosion resistant metal coating composition that has been used widely in Australia and elsewhere for building products, particularly profiled wall and roofing sheets, for a considerable number of years is an Al—Zn—Si alloy composition comprising 55% Al.
- the profiled sheets are usually manufactured by cold forming painted, metal alloy coated strip. Typically, the profiled sheets are manufactured by roll-forming the painted strip.
- magnesium and vanadium enhance specific aspects of corrosion performance of 55% Al—Zn—Si alloy metallic coated steel strip.
- V when V is included in Al—Zn—Si alloy coating compositions, the V brings about certain beneficial effects on product performance.
- the applicant has found that the level of mass loss from bare (unpainted) metallic coated steel strip surfaces tested on outdoor exposure is reduced by an average of 33% for a range of environments. As distinct from magnesium, the improvement in coating loss from bare (unpainted) surfaces is much greater than improvements in the level of edge undercutting for metallic coated steel strip with a paint coating.
- the present invention is a metal, typically steel, strip that has a coating of an Al—Zn—Si alloy that contains 0.3-10 wt. % Mg and 0.005-0.2 wt. % V in order to take advantage of the above-mentioned complementary aspects of corrosion performance of the coating.
- the addition of the Mg and the V improves both the bare mass loss of the strip and the edge undercutting of painted, metallic coated strip to a level that is greater than could be obtained by larger separate additions of each respective element alone.
- the coating alloy may be an Al—Zn—Si—Mg alloy that comprises the following ranges in % by weight of the elements Al, Zn, Si, and Mg:
- the coating alloy may be an Al—Zn—Si—Mg alloy that comprises the following ranges in % by weight of the elements Al, Zn, Si, and Mg:
- the coating alloy may contain less than 0.15 wt. % V.
- the coating alloy may contain less than 0.1 wt. % V.
- the coating alloy may contain at least 0.01 wt. % V.
- the coating alloy may contain at least 0.03 wt. % V.
- the coating alloy may contain other elements.
- the other elements may be present as unavoidable impurities and/or as deliberate alloy additions.
- the coating alloy may contain any one or more of Fe, Cr, Mn, Sr, and Ca.
- the coating may be a single layer as opposed to multiple layers.
- the coating may be a coating that does not include a non-equilibrium phase.
- the coating may be a coating that does not include an amorphous phase.
- the coated metal strip may have a paint coating on an outer surface of the alloy coating.
- the present invention is also a cold formed (e.g. roll formed) end-use product (e.g. profiled wall and roofing sheet) comprising steel strip that is coated with the above-described coating alloy and is optionally coated with a paint.
- a cold formed (e.g. roll formed) end-use product e.g. profiled wall and roofing sheet
- end-use product e.g. profiled wall and roofing sheet
- FIG. 1 is a schematic drawing of one embodiment of a continuous production line for producing steel strip coated with an Al—Zn—Si—Mg alloy in accordance with the method of the present invention.
- FIG. 2 is an Anodic Tafel plot showing a comparison of coating alloys, including an embodiment of an alloy coating in accordance with the present invention.
- coils of cold rolled steel strip are uncoiled at an uncoiling station 1 and successive uncoiled lengths of strip are welded end to end by a welder 2 and form a continuous length of strip.
- the strip is then passed successively through an accumulator 3 , a strip cleaning section 4 and a furnace assembly 5 .
- the furnace assembly 5 includes a preheater, a preheat reducing furnace, and a reducing furnace.
- the strip is heat treated in the furnace assembly 5 by careful control of process variables including: (i) the temperature profile in the furnaces, (ii) the reducing gas concentration in the furnaces, (iii) the gas flow rate through the furnaces, and (iv) strip residence time in the furnaces (i.e. line speed).
- the process variables in the furnace assembly 5 are controlled so that there is removal of iron oxide residues from the surface of the strip and removal of residual oils and iron fines from the surface of the strip.
- the heat treated strip is then passed via an outlet snout downwardly into and through a molten bath containing an Al—Zn—Si—Mg alloy held in a coating pot 6 and is coated with Al—Zn—Si—Mg alloy.
- the Al—Zn—Si—Mg alloy is maintained molten in the coating pot by use of heating inductors (not shown).
- Heating inductors not shown.
- Within the bath the strip passes around a sink roll and is taken upwardly out of the bath. Both surfaces of the strip are coated with the Al—Zn—Si—Mg alloy as it passes through the bath.
- the strip After leaving the coating bath 6 the strip passes vertically through a gas wiping station (not shown) at which its coated surfaces are subjected to jets of wiping gas to control the thickness of the coating.
- the coated strip is then passed through a cooling section 7 and subjected to forced cooling.
- the cooled, coated strip is then passed through a rolling section 8 that conditions the surface of the coated strip.
- the coated strip is thereafter coiled at a coiling station 10 .
- the present invention is based on research work carried out by the applicant on the known 55% Al—Zn—Si alloy coating on steel strip which found that magnesium and vanadium enhance specific aspects of corrosion performance of the coated steel strip.
- the research work included accelerated corrosion testing and outdoor exposure testing in acidic and marine environments for extended time periods.
- the Anodic Tafel plot in FIG. 2 illustrates the results of a part of the research work showing a comparison of alloy layers in neutral pH 0.1M NaCl.
- the plot shows the logarithm of the current density (“J”—in A/cm 2 ) against the electrode potential (in Volts) for 3 alloy compositions.
- the plot shows the results of research work on coatings of (a) the known 55% Al—Zn—Si alloy (“AZ”), (b) an Al—Zn—Si—Zn alloy containing Ca (“AM(Ca)”), and (c) an Al—Zn—Si—Zn alloy containing V in accordance with one embodiment of the present invention (“AM(V)”).
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- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Mechanical Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Coating With Molten Metal (AREA)
Abstract
A steel strip that has a coating of an Al—Zn—Si alloy that contains 0.3-10 wt. % Mg and 0.005-0.2 wt. % V.
Description
- The present application is a continuation of U.S. patent application Ser. No. 17/394,248, filed Aug. 4, 2021, which is a continuation of U.S. patent application Ser. No. 16/588,851, filed Sep. 30, 2019, which is a continuation of U.S. patent application Ser. No. 13/520,643, filed Sep. 24, 2012, which is a 371 application of International Application No. PCT/AU2011/000010, filed Jan. 6, 2011, which claims priority to Australian Application No. 2010900043, filed Jan. 6, 2010, the entire contents of each are incorporated by reference.
- The present invention relates to strip, typically steel strip, which has a corrosion-resistant metal alloy coating of an alloy that contains aluminium, zinc, and silicon and is hereinafter referred to as an “Al—Zn—Si alloy” on this basis.
- The present invention relates particularly but not exclusively to a corrosion-resistant metal alloy coating that contains aluminium, zinc, silicon, and magnesium as the main elements in the alloy coating and is hereinafter referred to as an “Al—Zn—Si—Mg alloy” on this basis. The alloy coating may contain other elements that are present as deliberate alloying additions or as unavoidable impurities.
- The present invention relates particularly but not exclusively to steel strip that is coated with the above-described Al—Zn—Si—Mg alloy and can be cold formed (e.g. by roll forming) into an end-use product, such as roofing products.
- Typically, the Al—Zn—Si—Mg alloy of the present invention comprises the following ranges in % by weight of the elements Al, Zn, Si, and Mg:
-
- Al: 40 to 60%
- Zn: 30 to 60%
- Si: 0.3 to 3%
- Mg: 0.3 to 10%.
- More typically, the Al—Zn—Si—Mg alloy of the present invention comprises the following ranges in % by weight of the elements Al, Zn, Si, and Mg:
-
- Al: 45 to 60%
- Zn: 35 to 50%
- Si: 1.2 to 2.5%
- Mg 1.0 to 3.0%.
- Depending on the end-use application, the metal-coated strip may be painted, for example with a polymeric paint, on one or both surfaces of the strip. In this regard, the metal-coated strip may be sold as an end product itself or may have a paint coating applied to one or both surfaces and be sold as a painted end product.
- The present invention relates particularly but not exclusively to steel strip that is coated with the above-described Al—Zn—Si—Mg alloy and is optionally coated with a paint and thereafter is cold formed (e.g. by roll forming) into an end-use product, such as building products (e.g. profiled wall and roofing sheets).
- The present invention relates particularly but not exclusively to a cold formed (e.g. roll formed) end-use product (e.g. profiled wall and roofing sheet) comprising steel strip that is coated with the above-described Al—Zn—Si—Mg alloy and is optionally coated with a paint.
- Typically, the corrosion-resistant metal alloy coating is formed on steel strip by a hot dip coating method.
- In the conventional hot-dip metal coating method, steel strip generally passes through one or more heat treatment furnaces and thereafter into and through a bath of molten metal alloy held in a coating pot.
- The metal alloy is usually maintained molten in the coating pot by the use of heating inductors. The strip usually exits the heat treatment furnaces via an outlet end section in the form of an elongated furnace exit chute or snout that dips into the bath. Within the bath the strip passes around one or more sink rolls and is taken upwardly out of the bath and is coated with the metal alloy as it passes through the bath.
- After leaving the coating bath the metal alloy coated strip passes through a coating thickness control station, such as a gas knife or gas wiping station, at which its coated surfaces are subjected to jets of wiping gas to control the thickness of the coating.
- The metal alloy coated strip then passes through a cooling section and is subjected to forced cooling.
- The cooled metal alloy coated strip may thereafter be optionally conditioned by passing the coated strip successively through a skin pass rolling section (also known as a temper rolling section) and a tension levelling section. The conditioned strip is coiled at a coiling station.
- The aluminium and zinc are provided in an Al—Zn—Si alloy coating on a steel strip for corrosion resistance.
- The aluminium, zinc, and magnesium are provided in an Al—Zn—Si alloy coating on a steel strip for corrosion resistance.
- The silicon is provided in both alloy types to prevent excessive alloying between a steel strip and the molten coating in the hot-dip coating method. A portion of the silicon takes part in a quaternary alloy layer formation but the majority of the silicon precipitates as needle-like, pure silicon particles during solidification. These needle-like silicon particles are also present in the inter-dendritic regions of the coating.
- One corrosion resistant metal coating composition that has been used widely in Australia and elsewhere for building products, particularly profiled wall and roofing sheets, for a considerable number of years is an Al—Zn—Si alloy composition comprising 55% Al. The profiled sheets are usually manufactured by cold forming painted, metal alloy coated strip. Typically, the profiled sheets are manufactured by roll-forming the painted strip.
- The addition of Mg to this known composition of 55% Al—Zn—Si coating composition has been proposed in the patent literature for a number of years, see for example U.S. Pat. No. 6,635,359 in the name of Nippon Steel Corporation. However, Al—Zn—Si—Mg alloy coatings on steel strip are not commercially available in Australia.
- The above description is not to be taken as an admission of the common general knowledge in Australia or elsewhere.
- It has been found by the applicant that magnesium and vanadium enhance specific aspects of corrosion performance of 55% Al—Zn—Si alloy metallic coated steel strip.
- In particular, it has been found by the applicant that when Mg is included in a 55% Al—Zn—Si coating composition, it brings about certain beneficial effects on product performance, such as improved cut-edge protection, by changing the nature of corrosion products formed in both marine and acid rain environments. This improvement in corrosion performance has been demonstrated by research work carried out by the applicant including comprehensive accelerated corrosion testing and outdoor exposure testing carried out by the applicant. For magnesium additions, the improvement in the level of edge undercutting for metallic coated steel with a paint coating is more pronounced than the improvement in bare surface corrosion of the metallic coating in marine environments.
- It has also been found by the applicant that when V is included in Al—Zn—Si alloy coating compositions, the V brings about certain beneficial effects on product performance. The applicant has found that the level of mass loss from bare (unpainted) metallic coated steel strip surfaces tested on outdoor exposure is reduced by an average of 33% for a range of environments. As distinct from magnesium, the improvement in coating loss from bare (unpainted) surfaces is much greater than improvements in the level of edge undercutting for metallic coated steel strip with a paint coating.
- The present invention is a metal, typically steel, strip that has a coating of an Al—Zn—Si alloy that contains 0.3-10 wt. % Mg and 0.005-0.2 wt. % V in order to take advantage of the above-mentioned complementary aspects of corrosion performance of the coating.
- More particularly, the addition of the Mg and the V improves both the bare mass loss of the strip and the edge undercutting of painted, metallic coated strip to a level that is greater than could be obtained by larger separate additions of each respective element alone.
- The coating alloy may be an Al—Zn—Si—Mg alloy that comprises the following ranges in % by weight of the elements Al, Zn, Si, and Mg:
-
- Al: 40 to 60%
- Zn: 30 to 60%
- Si: 0.3 to 3%
- Mg: 0.3 to 10%
- The coating alloy may be an Al—Zn—Si—Mg alloy that comprises the following ranges in % by weight of the elements Al, Zn, Si, and Mg:
-
- Al: 45 to 60%
- Zn: 35 to 50%
- Si: 1.2 to 2.5%
- Mg 1.0 to 3.0%.
- The coating alloy may contain less than 0.15 wt. % V.
- The coating alloy may contain less than 0.1 wt. % V.
- The coating alloy may contain at least 0.01 wt. % V.
- The coating alloy may contain at least 0.03 wt. % V.
- The coating alloy may contain other elements.
- The other elements may be present as unavoidable impurities and/or as deliberate alloy additions.
- By way of example, the coating alloy may contain any one or more of Fe, Cr, Mn, Sr, and Ca.
- The coating may be a single layer as opposed to multiple layers.
- The coating may be a coating that does not include a non-equilibrium phase.
- The coating may be a coating that does not include an amorphous phase.
- The coated metal strip may have a paint coating on an outer surface of the alloy coating.
- The present invention is also a cold formed (e.g. roll formed) end-use product (e.g. profiled wall and roofing sheet) comprising steel strip that is coated with the above-described coating alloy and is optionally coated with a paint.
- The present invention is described further by way of example with reference to the accompanying drawings, of which:
-
FIG. 1 is a schematic drawing of one embodiment of a continuous production line for producing steel strip coated with an Al—Zn—Si—Mg alloy in accordance with the method of the present invention; and -
FIG. 2 is an Anodic Tafel plot showing a comparison of coating alloys, including an embodiment of an alloy coating in accordance with the present invention. - With reference to
FIG. 1 , in use, coils of cold rolled steel strip are uncoiled at an uncoilingstation 1 and successive uncoiled lengths of strip are welded end to end by awelder 2 and form a continuous length of strip. - The strip is then passed successively through an
accumulator 3, astrip cleaning section 4 and a furnace assembly 5. The furnace assembly 5 includes a preheater, a preheat reducing furnace, and a reducing furnace. - The strip is heat treated in the furnace assembly 5 by careful control of process variables including: (i) the temperature profile in the furnaces, (ii) the reducing gas concentration in the furnaces, (iii) the gas flow rate through the furnaces, and (iv) strip residence time in the furnaces (i.e. line speed).
- The process variables in the furnace assembly 5 are controlled so that there is removal of iron oxide residues from the surface of the strip and removal of residual oils and iron fines from the surface of the strip.
- The heat treated strip is then passed via an outlet snout downwardly into and through a molten bath containing an Al—Zn—Si—Mg alloy held in a
coating pot 6 and is coated with Al—Zn—Si—Mg alloy. The Al—Zn—Si—Mg alloy is maintained molten in the coating pot by use of heating inductors (not shown). Within the bath the strip passes around a sink roll and is taken upwardly out of the bath. Both surfaces of the strip are coated with the Al—Zn—Si—Mg alloy as it passes through the bath. - After leaving the
coating bath 6 the strip passes vertically through a gas wiping station (not shown) at which its coated surfaces are subjected to jets of wiping gas to control the thickness of the coating. - The coated strip is then passed through a
cooling section 7 and subjected to forced cooling. - The cooled, coated strip is then passed through a rolling
section 8 that conditions the surface of the coated strip. - The coated strip is thereafter coiled at a coiling
station 10. - As is indicated above, the present invention is based on research work carried out by the applicant on the known 55% Al—Zn—Si alloy coating on steel strip which found that magnesium and vanadium enhance specific aspects of corrosion performance of the coated steel strip.
- The research work included accelerated corrosion testing and outdoor exposure testing in acidic and marine environments for extended time periods.
- The Anodic Tafel plot in
FIG. 2 illustrates the results of a part of the research work showing a comparison of alloy layers in neutral pH 0.1M NaCl. The plot shows the logarithm of the current density (“J”—in A/cm2) against the electrode potential (in Volts) for 3 alloy compositions. The plot shows the results of research work on coatings of (a) the known 55% Al—Zn—Si alloy (“AZ”), (b) an Al—Zn—Si—Zn alloy containing Ca (“AM(Ca)”), and (c) an Al—Zn—Si—Zn alloy containing V in accordance with one embodiment of the present invention (“AM(V)”). - The plot of
FIG. 2 compares the corrosion performance of the alloy coatings (a), (b), and (c). The plot and other results obtained by the applicant indicate that: -
- (a) the AM(V) alloy coating of the present invention had a lower corrosion current at a given corrosion potential than the other alloy coatings (1.5-2 times improvement of AM(V) over AM(Ca));
- (b) the AM(V) alloy coating of the present invention had more noble corrosion potential compared to AM(Ca) (+0.03 V and +0.11 V respectively);
- (c) the AM(V) alloy coating of the present invention had more noble pitting potential compared to AM(Ca) (+0.04 V and +0.18 V respectively); and
- (d) the AM(V) alloy coating of the present invention had significantly lower oxidative current under anodic polarisation—compared to AM(Ca), at −0.25 V, the oxidative current is about 20000 times less for AM(V).
- These improvements in the resistance for anodic dissolution of the alloy layer imply that upon exposure of the alloy coating of the present invention to corrodants (salt, acid, and dissolved oxygen) the metallurgical phase will corrode at a slow rate and the mode of corrosion will be generalised and less prone to localised and pitting corrosion mode. These properties will impart a longer life in an end-use product, as it will be rendered less likely to red rust staining, metal coating blistering and substrate perforation.
- Many modifications may be made to the present invention as described above without departing from the spirit and scope of the invention.
Claims (10)
1. A metal strip that has a coating of an Al—Zn—Si alloy that contains 0.3-10 wt. % Mg and 0.005-0.2 wt. % V.
2. The metal strip defined in claim 1 wherein the coating alloy is an Al—Zn—Si—Mg alloy that comprises the following ranges in % by weight of the elements Al, Zn, Si, and Mg:
Al: 40 to 60%
Zn: 30 to 60%
Si: 0.3 to 3%
Mg: 0.3 to 10%
3. The metal strip defined in claim 1 where the coating alloy is an Al—Zn—Si—Mg alloy that comprises the following ranges in % by weight of the elements Al, Zn, Si, and Mg:
Al: 45 to 60%
Zn: 35 to 50%
Si: 1.2 to 2.5%
Mg 1.0 to 3.0%.
4. The metal strip defined in claim 1 wherein the alloy coating contains less than 0.15 wt. % V.
5. The metal strip defined in claim 1 wherein the alloy coating contains less than 0.1 wt. % V.
6. The metal strip defined in claim 1 wherein the alloy coating contains at least 0.01 wt. % V.
7. The metal strip defined in claim 1 wherein the alloy coating contains at least 0.03 wt. % V.
8. The metal strip defined in claim 1 wherein the alloy coating contains other elements present as unavoidable impurities and/or as deliberate alloy additions.
9. The metal strip defined in claim 1 wherein the alloy coating is a single layer.
10. A cold formed end-use product comprising the metal strip defined in claim 1 .
Priority Applications (1)
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US18/172,476 US20230279534A1 (en) | 2010-01-06 | 2023-02-22 | Metal coated steel strip |
Applications Claiming Priority (7)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
AU2010900043A AU2010900043A0 (en) | 2010-01-06 | Metal coated steel strip | |
AU2010900043 | 2010-01-06 | ||
PCT/AU2011/000010 WO2011082450A1 (en) | 2010-01-06 | 2011-01-06 | Metal coated steel strip |
US201213520643A | 2012-09-24 | 2012-09-24 | |
US16/588,851 US20200024717A1 (en) | 2010-01-06 | 2019-09-30 | Metal coated steel strip |
US17/394,248 US20220025501A1 (en) | 2010-01-06 | 2021-08-04 | Metal coated steel strip |
US18/172,476 US20230279534A1 (en) | 2010-01-06 | 2023-02-22 | Metal coated steel strip |
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US17/394,248 Continuation US20220025501A1 (en) | 2010-01-06 | 2021-08-04 | Metal coated steel strip |
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US20230279534A1 true US20230279534A1 (en) | 2023-09-07 |
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ID=44305128
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US13/520,643 Abandoned US20130011693A1 (en) | 2010-01-06 | 2011-01-06 | Metal coated steel strip |
US16/588,851 Abandoned US20200024717A1 (en) | 2010-01-06 | 2019-09-30 | Metal coated steel strip |
US17/394,248 Abandoned US20220025501A1 (en) | 2010-01-06 | 2021-08-04 | Metal coated steel strip |
US18/172,476 Pending US20230279534A1 (en) | 2010-01-06 | 2023-02-22 | Metal coated steel strip |
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US13/520,643 Abandoned US20130011693A1 (en) | 2010-01-06 | 2011-01-06 | Metal coated steel strip |
US16/588,851 Abandoned US20200024717A1 (en) | 2010-01-06 | 2019-09-30 | Metal coated steel strip |
US17/394,248 Abandoned US20220025501A1 (en) | 2010-01-06 | 2021-08-04 | Metal coated steel strip |
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US (4) | US20130011693A1 (en) |
EP (1) | EP2521801B1 (en) |
JP (2) | JP6309192B2 (en) |
KR (6) | KR20230048464A (en) |
CN (1) | CN102712988B (en) |
ES (1) | ES2753155T3 (en) |
MY (1) | MY162981A (en) |
NZ (1) | NZ600606A (en) |
TW (1) | TWI519675B (en) |
WO (1) | WO2011082450A1 (en) |
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NZ562141A (en) * | 2005-04-05 | 2009-10-30 | Bluescope Steel Ltd | Metal-coated steel strip comprising a coating of an aluminium-zic-silicon alloy that contains magnesium |
KR20230048464A (en) * | 2010-01-06 | 2023-04-11 | 블루스코프 스틸 리미티드 | Metal coated steel strip |
KR102014204B1 (en) * | 2012-08-01 | 2019-10-23 | 블루스코프 스틸 리미티드 | Metal coated steel strip |
UA118185C2 (en) | 2013-02-06 | 2018-12-10 | Арселорміттал | Method of treatment of a running ferrous alloy sheet and treatment line for its implementation |
CN108913965B (en) * | 2018-07-31 | 2021-02-26 | 中研智能装备有限公司 | ZnAlTiSiB anticorrosive coating for steel structure and preparation method thereof |
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US4735867A (en) * | 1985-12-06 | 1988-04-05 | Kaiser Aluminum & Chemical Corporation | Corrosion resistant aluminum core alloy |
SE510563C2 (en) * | 1990-04-13 | 1999-06-07 | Centre Rech Metallurgique | Methods for continuous hot dip coating of a steel strip and steel strip coated with a Zn / Al alloy |
JPH06116748A (en) * | 1992-10-08 | 1994-04-26 | Sumitomo Metal Ind Ltd | Multilayer al alloy plated metallic material excellent in corrosion resistance |
CN1261614C (en) * | 2000-02-29 | 2006-06-28 | 新日本制铁株式会社 | Plated steel product having high resistance and excellent formability and method for production thereof |
EP1193323B1 (en) * | 2000-02-29 | 2016-04-20 | Nippon Steel & Sumitomo Metal Corporation | Plated steel product having high corrosion resistance and excellent formability and method for production thereof |
CN1215194C (en) * | 2001-01-31 | 2005-08-17 | 杰富意钢铁株式会社 | Surface treated steel and method for production thereof |
JP3654521B2 (en) * | 2001-01-31 | 2005-06-02 | Jfeスチール株式会社 | Painted steel sheet excellent in workability and corrosion resistance of processed part and method for producing the same |
JP2002241962A (en) * | 2001-02-13 | 2002-08-28 | Sumitomo Metal Ind Ltd | HOT DIP Zn-Al-Mg ALLOY PLATED STEEL SHEET AND PRODUCTION METHOD THEREFOR |
JP2003277905A (en) * | 2002-03-19 | 2003-10-02 | Jfe Steel Kk | HOT DIP Al-Zn BASE ALLOY COATED STEEL SHEET EXCELLENT IN SURFACE APPEARANCE AND BENDING WORKABILITY AND ITS PRODUCING METHOD |
JP2003306757A (en) * | 2002-04-18 | 2003-10-31 | Jfe Steel Kk | HOT DIP Al-Zn ALLOY-COATED STEEL SHEET AND METHOD OF PRODUCING THE SAME |
US7048815B2 (en) * | 2002-11-08 | 2006-05-23 | Ues, Inc. | Method of making a high strength aluminum alloy composition |
CN101405421B (en) * | 2006-03-20 | 2012-04-04 | 新日本制铁株式会社 | Highly corrosion-resistant hot dip galvanized steel stock |
CN101535521B (en) * | 2006-08-29 | 2015-08-19 | 蓝野钢铁有限公司 | There is the steel band of metal alloy coating and on steel band, form the method for this coating |
WO2009055843A1 (en) * | 2007-10-29 | 2009-05-07 | Bluescope Steel Limited | Metal-coated steel strip |
KR20100131417A (en) * | 2008-03-13 | 2010-12-15 | 블루스코프 스틸 리미티드 | Metal-coated steel strip |
KR20110060680A (en) * | 2009-11-30 | 2011-06-08 | 동부제철 주식회사 | Coating composition, and method for coating of steel using the same, and coating steel coated coating composition |
KR20230048464A (en) * | 2010-01-06 | 2023-04-11 | 블루스코프 스틸 리미티드 | Metal coated steel strip |
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2011
- 2011-01-06 KR KR1020237011173A patent/KR20230048464A/en not_active Application Discontinuation
- 2011-01-06 KR KR1020197006338A patent/KR20190026057A/en active Application Filing
- 2011-01-06 US US13/520,643 patent/US20130011693A1/en not_active Abandoned
- 2011-01-06 TW TW100100464A patent/TWI519675B/en active
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- 2011-01-06 JP JP2012547410A patent/JP6309192B2/en active Active
- 2011-01-06 KR KR1020187004856A patent/KR20180020325A/en active Application Filing
- 2011-01-06 CN CN201180005572.3A patent/CN102712988B/en active Active
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2016
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2021
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KR20120112756A (en) | 2012-10-11 |
NZ600606A (en) | 2014-02-28 |
US20220025501A1 (en) | 2022-01-27 |
KR20210104914A (en) | 2021-08-25 |
KR20200103129A (en) | 2020-09-01 |
TWI519675B (en) | 2016-02-01 |
KR20190026057A (en) | 2019-03-12 |
EP2521801B1 (en) | 2019-10-09 |
TW201132797A (en) | 2011-10-01 |
MY162981A (en) | 2017-07-31 |
US20200024717A1 (en) | 2020-01-23 |
WO2011082450A1 (en) | 2011-07-14 |
KR20230048464A (en) | 2023-04-11 |
US20130011693A1 (en) | 2013-01-10 |
CN102712988A (en) | 2012-10-03 |
ES2753155T3 (en) | 2020-04-07 |
EP2521801A1 (en) | 2012-11-14 |
CN102712988B (en) | 2014-12-31 |
JP6309192B2 (en) | 2018-04-11 |
KR20180020325A (en) | 2018-02-27 |
JP2017008415A (en) | 2017-01-12 |
EP2521801A4 (en) | 2014-04-23 |
JP2013516549A (en) | 2013-05-13 |
AU2011204744A1 (en) | 2012-07-05 |
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