WO2008141398A1 - Bande d'acier recouverte de métal - Google Patents

Bande d'acier recouverte de métal Download PDF

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Publication number
WO2008141398A1
WO2008141398A1 PCT/AU2008/000738 AU2008000738W WO2008141398A1 WO 2008141398 A1 WO2008141398 A1 WO 2008141398A1 AU 2008000738 W AU2008000738 W AU 2008000738W WO 2008141398 A1 WO2008141398 A1 WO 2008141398A1
Authority
WO
WIPO (PCT)
Prior art keywords
strip
cooling
coating
phase
method defined
Prior art date
Application number
PCT/AU2008/000738
Other languages
English (en)
Inventor
Ross Mcdowall Smith
Qiyang Liu
Joe Williams
Original Assignee
Bluescope Steel Limited
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority claimed from AU2007902778A external-priority patent/AU2007902778A0/en
Application filed by Bluescope Steel Limited filed Critical Bluescope Steel Limited
Priority to AU2008253615A priority Critical patent/AU2008253615B2/en
Publication of WO2008141398A1 publication Critical patent/WO2008141398A1/fr

Links

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
    • C23C2/12—Aluminium or alloys based thereon

Definitions

  • the present invention relates to strip, typically- steel strip, which has a corrosion-resistant metal alloy coating.
  • the present invention relates particularly to a corrosion-resistant metal alloy coating that contains aluminium-zinc-silicon-magnesium as the main elements in the alloy, 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.
  • Al-Zn-Si-Mg alloy is understood to cover alloys that contain such other elements as deliberate alloying additions or as unavoidable impurities.
  • 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 can be cold formed (e.g. by roll forming) into an end-use product, such as roofing products.
  • the Al-Zn-Si-Mg alloy comprises the following ranges in % by weight of the elements aluminium, zinc, silicon, and magnesium:
  • Aluminium 40 to 60 % by weight
  • Zinc 40 to 60 % by weight
  • Silicon 0.3 to 3% by weight
  • Magnesium 0.3 to 10 % by weight
  • 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 heat treatment furnace that is adjacent a coating pot has an outlet snout that extends downwardly to a location below an upper surface of the bath.
  • 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 metal- coated strip may be painted, for example with a polymeric paint, on one or both surfaces of the strip.
  • 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.
  • a 55%A1-Zn alloy coating normally consists of alpha-Al phase dendrites and beta-Zn phase in interdendritic regions. Silicon is added to the coating alloy composition to prevent excessive alloying between the steel substrate and the molten coating in the hot-dip coating method. A portion of the silicon takes part in 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 present in interdendritic regions.
  • Mg when Mg is included in a 55%A1-Zn-Si alloy coating composition, Mg brings about certain beneficial effects on product performance, such as improved cut-edge protection, by changing the nature of corrosion products formed.
  • Mg reacts with Si to form a Mg 2 Si phase and that the formation of Mg 2 Si phase compromises the abovementioned beneficial effects of Mg in many ways.
  • the Mg 2 Si phase is more voluminous than Si, is brittle, and has a "Chinese script" morphology with sharp edges.
  • the Mg 2 Si forms as a continuous film in interdendritic regions, often growing across the full thickness of the thin metallic coating.
  • the Mg 2 Si phase provides crack initiation sites, crack propagation pathways and potential corrosion conduits to the base steel and is undesirable on that basis.
  • Patent literature reviewed by the applicant has highlighted that increasing the cooling rate during solidification can refine the dendrite solidification structure of a 55%A1-Zn-Si alloy coating and also the size of Mg 2 Si phase in the structure.
  • cooling a molten coating at rates high enough to sufficiently refine the Mg 2 Si phase is very difficult to achieve without damaging the soft coating surface and consequently has not been an option on this basis.
  • the present invention provides a method of forming a metal coated strip, such as a steel strip, that comprises solidifying a molten coating of an Al-Zn-Si-Mg alloy on the strip with a high rate of cooling only after a sufficiently strong, solid supporting network of alpha-Al phase dendrites has been established in the coating and before a Mg 2 Si phase has started to form in the coating.
  • a metal coated strip such as a steel strip, that comprises:
  • the present invention is based on a realisation that it is beneficial to solidify a molten coating of an Al-Zn-Si-Mg alloy on a strip, such as a steel strip, with a high rate of cooling only after a sufficiently strong, solid supporting network of alpha-Al phase dendrites has been established in the coating and before a Mg 2 Si phase has started to form in the coating.
  • a start temperature for the high rate of cooling is 500 0 C.
  • the start temperature depends on a number of factors.
  • One important factor is the composition of the Al-Zn-Si-Mg alloy coating.
  • a skilled person can readily determine by experimentation an appropriate start temperature.
  • the start temperature is in a range of 460 - 500 0 C .
  • the start temperature is a temperature at which at least 50% by volume of the coating has solidified as dendrites of an alpha-Al phase.
  • the start temperature may be a temperature at which at least 60% by volume of the coating has solidified as dendrites of an alpha-Al phase.
  • the high rate of cooling is at least 150°C/sec.
  • the high rate of cooling may be at least 200°C/sec.
  • the high rate of cooling is in a range of 150-2000°C/sec.
  • a finish temperature for the high rate of cooling is in a range of 280-330 0 C.
  • an average rate of cooling at the high rates of cooling is at least 250°C/s.
  • the cooling step includes an initial cooling step down to the start temperature, with the initial cooling step being at a lower rate than the later high rate of cooling.
  • the lower cooling rate is in a range of 30-150°C/sec.
  • the coating is 5-30 microns in thickness.
  • the method further comprises forming a coating of a paint on the coated strip.
  • a strip such as a steel strip, that has a coating of an Al-Zn-Si-Mg alloy on the strip that is formed by the above-described method.
  • the coating is in a range of 5-30 microns in thickness per side of the strip.
  • the coating has a microstructure that comprises alpha-Al phase dendrites, a Zn-rich phase (such as beta-Zn phase and/or MgZn 2 phase) in interdendritic regions, and fragmented Mg 2 Si phase in interdendritic regions.
  • a Zn-rich phase such as beta-Zn phase and/or MgZn 2 phase
  • the present invention is based on experimental work carried out by the applicant.
  • the samples were heated in an annealing furnace to a temperature and for a time that was sufficient to melt the alloy coatings and then cooled to ambient temperature at selected cooling rates.
  • Figures 1 and 2 are images of the microstructures of representative samples from items (a) and (b) above after the samples were cooled to ambient temperature.
  • the microstructure in Figure 1 shows that the conventional cooling rate produced a coarse Mg 2 Si phase - identified by the arrows in the Figure - in an interdendritic region between alpha-Al phase dendrites.
  • the lighter regions in the image are Zn-rich phases (including beta-Zn and/or MgZn 2 ) in interdendritic regions.
  • the microstructure in Figure 2 shows that the initial relatively slow cooling rate followed by the high cooling rate produced a microstructure having fine Mg 2 Si phase identified by the arrows in the Figure.
  • the microstructure also comprises alpha-Al phase dendrites and Zn-rich phases (including beta-Zn and/or MgZn 2 ) in interdendritic regions.

Landscapes

  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Mechanical Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Coating With Molten Metal (AREA)

Abstract

L'invention se rapporte à un procédé de formation d'une bande recouverte de métal, telle qu'une bande d'acier. Le procédé comprend les étapes consistant à solidifier un revêtement fondu d'un alliage Al-Zn-Si-Mg sur la bande à une vitesse de refroidissement élevée seulement après qu'un réseau support, solide, suffisamment fort, de dendrites de phase alpha a été constitué dans le revêtement et avant qu'une phase Mg2Si ait commencé à se former dans le revêtement.
PCT/AU2008/000738 2007-05-24 2008-05-26 Bande d'acier recouverte de métal WO2008141398A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AU2008253615A AU2008253615B2 (en) 2007-05-24 2008-05-26 Metal-coated steel strip

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
AU2007902778 2007-05-24
AU2007902778A AU2007902778A0 (en) 2007-05-24 Metal-coated steel strip

Publications (1)

Publication Number Publication Date
WO2008141398A1 true WO2008141398A1 (fr) 2008-11-27

Family

ID=40031335

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/AU2008/000738 WO2008141398A1 (fr) 2007-05-24 2008-05-26 Bande d'acier recouverte de métal

Country Status (2)

Country Link
AU (1) AU2008253615B2 (fr)
WO (1) WO2008141398A1 (fr)

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2010102343A1 (fr) 2009-03-13 2010-09-16 Bluescope Steel Limited Protection contre la corrosion avec des revêtements à base d'al/zn
EP2250296A1 (fr) * 2008-03-13 2010-11-17 Bluescope Steel Limited Bande d acier revêtue de métal
WO2010135779A1 (fr) * 2009-05-28 2010-12-02 Bluescope Steel Limited Bande d'acier métallisée
AU2015213419B2 (en) * 2009-03-13 2017-06-08 Bluescope Steel Limited Corrosion protection with al/zn-based coatings
WO2020067678A1 (fr) * 2018-09-27 2020-04-02 주식회사 포스코 Tôle d'acier plaquée à résistance à la corrosion élevée, pourvue d'une excellente adhérence de placage et d'une excellente résistance à la fragilisation par métal liquide
EP2238273B1 (fr) * 2008-02-07 2020-08-12 Bluescope Steel Limited Bande d'acier revêtue de métal
AU2019204599B2 (en) * 2009-03-13 2020-10-29 Bluescope Steel Limited Corrosion protection with al/zn-based coatings
JP2021001374A (ja) * 2019-06-21 2021-01-07 Ｊｆｅスチール株式会社 溶融Ａｌ−Ｚｎ系めっき鋼板の製造方法

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4401727A (en) * 1982-06-23 1983-08-30 Bethlehem Steel Corporation Ferrous product having an alloy coating thereon of Al-Zn-Mg-Si Alloy, and method
US4812371A (en) * 1986-11-17 1989-03-14 Nippon Steel Corporation Zn-Al hot-dip galvanized steel sheet having improved resistance against secular peeling of coating
US5091150A (en) * 1986-07-14 1992-02-25 Nuova Italsider Spa Zinc-aluminium based alloy for coating steel products
JP2001355055A (ja) * 2000-04-11 2001-12-25 Nippon Steel Corp 未塗装加工部ならびに塗装端面部の耐食性に優れた溶融Ｚｎ−Ａｌ−Ｍｇ−Ｓｉめっき鋼材

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4401727A (en) * 1982-06-23 1983-08-30 Bethlehem Steel Corporation Ferrous product having an alloy coating thereon of Al-Zn-Mg-Si Alloy, and method
US5091150A (en) * 1986-07-14 1992-02-25 Nuova Italsider Spa Zinc-aluminium based alloy for coating steel products
US4812371A (en) * 1986-11-17 1989-03-14 Nippon Steel Corporation Zn-Al hot-dip galvanized steel sheet having improved resistance against secular peeling of coating
JP2001355055A (ja) * 2000-04-11 2001-12-25 Nippon Steel Corp 未塗装加工部ならびに塗装端面部の耐食性に優れた溶融Ｚｎ−Ａｌ−Ｍｇ−Ｓｉめっき鋼材

Cited By (32)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP2238273B1 (fr) * 2008-02-07 2020-08-12 Bluescope Steel Limited Bande d'acier revêtue de métal
CN101910444B (zh) * 2008-03-13 2013-11-27 蓝野钢铁有限公司 金属镀覆钢带
EP2250296A1 (fr) * 2008-03-13 2010-11-17 Bluescope Steel Limited Bande d acier revêtue de métal
EP2250297A1 (fr) * 2008-03-13 2010-11-17 Bluescope Steel Limited Bande d acier revêtue de métal
US11840763B2 (en) 2008-03-13 2023-12-12 Bluescope Steel Limited Metal-coated steel strip
EP2250297A4 (fr) * 2008-03-13 2011-03-09 Bluescope Steel Ltd Bande d acier revêtue de métal
EP2250296A4 (fr) * 2008-03-13 2011-03-09 Bluescope Steel Ltd Bande d acier revêtue de métal
EP2406408A1 (fr) * 2009-03-13 2012-01-18 Bluescope Steel Limited Protection contre la corrosion avec des revêtements à base d'al/zn
WO2010102343A1 (fr) 2009-03-13 2010-09-16 Bluescope Steel Limited Protection contre la corrosion avec des revêtements à base d'al/zn
AU2021200579B2 (en) * 2009-03-13 2023-04-27 Bluescope Steel Limited Corrosion protection with AL/ZN-based coatings
US11807941B2 (en) 2009-03-13 2023-11-07 Bluescope Steel Limited Corrosion protection with Al/Zn-based coatings
CN102341523A (zh) * 2009-03-13 2012-02-01 蓝野钢铁有限公司 使用Al/Zn基镀层的防腐保护
EP2406408A4 (fr) * 2009-03-13 2014-09-03 Bluescope Steel Ltd Protection contre la corrosion avec des revêtements à base d'al/zn
JP2015227511A (ja) * 2009-03-13 2015-12-17 ブルースコープ・スティール・リミテッドＢｌｕｅｓｃｏｐｅ Ｓｔｅｅｌ Ｌｉｍｉｔｅｄ Ａｌ／Ｚｎベースの被膜を有する腐食保護
JP2021113359A (ja) * 2009-03-13 2021-08-05 ブルースコープ・スティール・リミテッドBluescope Steel Limited Ａｌ／Ｚｎベースの被膜を有する腐食保護
AU2015213419B2 (en) * 2009-03-13 2017-06-08 Bluescope Steel Limited Corrosion protection with al/zn-based coatings
EP3757245A1 (fr) * 2009-03-13 2020-12-30 Bluescope Steel Limited Protection contre la corrosion avec des revêtements à base d'al/zn
AU2019204599B2 (en) * 2009-03-13 2020-10-29 Bluescope Steel Limited Corrosion protection with al/zn-based coatings
US11512377B2 (en) 2009-03-13 2022-11-29 Bluescope Steel Limited Corrosion protection with Al/Zn-based coatings
EP2406408B1 (fr) 2009-03-13 2020-10-14 Bluescope Steel Limited Protection contre la corrosion avec des revêtements à base d'al/zn
US10731241B2 (en) 2009-05-28 2020-08-04 Bluescope Steel Limited Metal-coated steel strip
CN102449182A (zh) * 2009-05-28 2012-05-09 蓝野钢铁有限公司 金属镀覆钢带
WO2010135779A1 (fr) * 2009-05-28 2010-12-02 Bluescope Steel Limited Bande d'acier métallisée
AU2010251878B2 (en) * 2009-05-28 2016-05-19 Bluescope Steel Limited Metal-coated steel strip
JP2012528244A (ja) * 2009-05-28 2012-11-12 ブルースコープ・スティール・リミテッド 金属被覆スチールストリップ
US20120135261A1 (en) * 2009-05-28 2012-05-31 Bluescope Steel Limited Metal-coated steel strip
WO2020067678A1 (fr) * 2018-09-27 2020-04-02 주식회사 포스코 Tôle d'acier plaquée à résistance à la corrosion élevée, pourvue d'une excellente adhérence de placage et d'une excellente résistance à la fragilisation par métal liquide
JP7187686B2 (ja) 2018-09-27 2022-12-12 ポスコ 溶接液化脆性に対する抵抗性及びめっき密着性に優れた高耐食めっき鋼板
US11530470B2 (en) 2018-09-27 2022-12-20 Posco Co., Ltd Highly corrosion-resistant plated steel sheet having excellent plating adhesion and resistance to liquid metal embrittlement
JP2022501508A (ja) * 2018-09-27 2022-01-06 ポスコPosco 溶接液化脆性に対する抵抗性及びめっき密着性に優れた高耐食めっき鋼板
JP7120166B2 (ja) 2019-06-21 2022-08-17 Ｊｆｅスチール株式会社 溶融Ａｌ－Ｚｎ系めっき鋼板の製造方法
JP2021001374A (ja) * 2019-06-21 2021-01-07 Ｊｆｅスチール株式会社 溶融Ａｌ−Ｚｎ系めっき鋼板の製造方法

Also Published As

Publication number Publication date
AU2008253615A1 (en) 2008-11-27
AU2008253615B2 (en) 2013-05-02

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