KR101568474B1 - HOT DIP Zn ALLOY PLATED STEEL SHEET HAVING EXCELLENT BLACKENING-RESISTANCE AND SURFACE APPEARANCE AND METHOD FOR MANUFACTURING THE SAME - Google Patents
HOT DIP Zn ALLOY PLATED STEEL SHEET HAVING EXCELLENT BLACKENING-RESISTANCE AND SURFACE APPEARANCE AND METHOD FOR MANUFACTURING THE SAME Download PDFInfo
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- KR101568474B1 KR101568474B1 KR1020130130117A KR20130130117A KR101568474B1 KR 101568474 B1 KR101568474 B1 KR 101568474B1 KR 1020130130117 A KR1020130130117 A KR 1020130130117A KR 20130130117 A KR20130130117 A KR 20130130117A KR 101568474 B1 KR101568474 B1 KR 101568474B1
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- steel sheet
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- 238000000034 method Methods 0.000 title claims abstract description 31
- 229910000831 Steel Inorganic materials 0.000 title claims description 48
- 239000010959 steel Substances 0.000 title claims description 48
- 238000004519 manufacturing process Methods 0.000 title abstract description 12
- 229910001297 Zn alloy Inorganic materials 0.000 title description 10
- 229910001335 Galvanized steel Inorganic materials 0.000 claims abstract description 32
- 239000008397 galvanized steel Substances 0.000 claims abstract description 32
- 229910052751 metal Inorganic materials 0.000 claims abstract description 19
- 239000002184 metal Substances 0.000 claims abstract description 19
- 230000008569 process Effects 0.000 claims abstract description 18
- 229910017706 MgZn Inorganic materials 0.000 claims abstract description 17
- 230000008520 organization Effects 0.000 claims abstract description 11
- 239000010953 base metal Substances 0.000 claims abstract description 4
- 230000003746 surface roughness Effects 0.000 claims description 8
- 238000007747 plating Methods 0.000 description 74
- 239000011701 zinc Substances 0.000 description 52
- 239000010410 layer Substances 0.000 description 41
- 238000001816 cooling Methods 0.000 description 39
- 238000005260 corrosion Methods 0.000 description 31
- 230000007797 corrosion Effects 0.000 description 31
- 239000011777 magnesium Substances 0.000 description 31
- 229910052749 magnesium Inorganic materials 0.000 description 14
- 229910052725 zinc Inorganic materials 0.000 description 14
- 229910052782 aluminium Inorganic materials 0.000 description 13
- 230000000052 comparative effect Effects 0.000 description 11
- 230000001965 increasing effect Effects 0.000 description 11
- HCHKCACWOHOZIP-UHFFFAOYSA-N Zinc Chemical compound [Zn] HCHKCACWOHOZIP-UHFFFAOYSA-N 0.000 description 10
- 238000005246 galvanizing Methods 0.000 description 10
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 9
- 230000000694 effects Effects 0.000 description 9
- 239000007789 gas Substances 0.000 description 9
- 229910000765 intermetallic Inorganic materials 0.000 description 9
- 229910045601 alloy Inorganic materials 0.000 description 7
- 239000000956 alloy Substances 0.000 description 7
- 239000000463 material Substances 0.000 description 7
- 230000008859 change Effects 0.000 description 5
- 239000011247 coating layer Substances 0.000 description 5
- 238000007711 solidification Methods 0.000 description 5
- 230000008023 solidification Effects 0.000 description 5
- 241001163841 Albugo ipomoeae-panduratae Species 0.000 description 4
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 4
- 229910052742 iron Inorganic materials 0.000 description 4
- 239000000047 product Substances 0.000 description 4
- 229910018134 Al-Mg Inorganic materials 0.000 description 3
- 229910018467 Al—Mg Inorganic materials 0.000 description 3
- 230000003247 decreasing effect Effects 0.000 description 3
- 239000012535 impurity Substances 0.000 description 3
- 238000007254 oxidation reaction Methods 0.000 description 3
- 150000003839 salts Chemical class 0.000 description 3
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- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 3
- CSCPPACGZOOCGX-UHFFFAOYSA-N Acetone Chemical compound CC(C)=O CSCPPACGZOOCGX-UHFFFAOYSA-N 0.000 description 2
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 description 2
- 229910000640 Fe alloy Inorganic materials 0.000 description 2
- XLOMVQKBTHCTTD-UHFFFAOYSA-N Zinc monoxide Chemical compound [Zn]=O XLOMVQKBTHCTTD-UHFFFAOYSA-N 0.000 description 2
- 229910009369 Zn Mg Inorganic materials 0.000 description 2
- 229910007573 Zn-Mg Inorganic materials 0.000 description 2
- 238000000137 annealing Methods 0.000 description 2
- 230000008901 benefit Effects 0.000 description 2
- 230000015572 biosynthetic process Effects 0.000 description 2
- 239000004566 building material Substances 0.000 description 2
- 230000015271 coagulation Effects 0.000 description 2
- 238000005345 coagulation Methods 0.000 description 2
- 239000000112 cooling gas Substances 0.000 description 2
- 238000002845 discoloration Methods 0.000 description 2
- 230000006872 improvement Effects 0.000 description 2
- 229910052757 nitrogen Inorganic materials 0.000 description 2
- 230000003647 oxidation Effects 0.000 description 2
- 230000001590 oxidative effect Effects 0.000 description 2
- 229920006395 saturated elastomer Polymers 0.000 description 2
- 238000009736 wetting Methods 0.000 description 2
- 229910000851 Alloy steel Inorganic materials 0.000 description 1
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 1
- FYYHWMGAXLPEAU-UHFFFAOYSA-N Magnesium Chemical compound [Mg] FYYHWMGAXLPEAU-UHFFFAOYSA-N 0.000 description 1
- 229910000861 Mg alloy Inorganic materials 0.000 description 1
- 239000000654 additive Substances 0.000 description 1
- 238000003915 air pollution Methods 0.000 description 1
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 1
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- 238000005452 bending Methods 0.000 description 1
- 230000000903 blocking effect Effects 0.000 description 1
- 239000010960 cold rolled steel Substances 0.000 description 1
- 150000001875 compounds Chemical class 0.000 description 1
- 238000011109 contamination Methods 0.000 description 1
- 230000006866 deterioration Effects 0.000 description 1
- 238000003618 dip coating Methods 0.000 description 1
- 238000010828 elution Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- 239000001257 hydrogen Substances 0.000 description 1
- 229910052739 hydrogen Inorganic materials 0.000 description 1
- 230000001939 inductive effect Effects 0.000 description 1
- 230000007246 mechanism Effects 0.000 description 1
- 238000002844 melting Methods 0.000 description 1
- 230000008018 melting Effects 0.000 description 1
- 150000002736 metal compounds Chemical class 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 238000000465 moulding Methods 0.000 description 1
- 230000000704 physical effect Effects 0.000 description 1
- 239000002244 precipitate Substances 0.000 description 1
- 238000003825 pressing Methods 0.000 description 1
- 238000010791 quenching Methods 0.000 description 1
- 230000000171 quenching effect Effects 0.000 description 1
- 230000001105 regulatory effect Effects 0.000 description 1
- 238000011160 research Methods 0.000 description 1
- 238000005507 spraying Methods 0.000 description 1
- 239000002344 surface layer Substances 0.000 description 1
- 238000004381 surface treatment Methods 0.000 description 1
- 239000011573 trace mineral Substances 0.000 description 1
- 235000013619 trace mineral Nutrition 0.000 description 1
- UGZADUVQMDAIAO-UHFFFAOYSA-L zinc hydroxide Chemical compound [OH-].[OH-].[Zn+2] UGZADUVQMDAIAO-UHFFFAOYSA-L 0.000 description 1
- 229940007718 zinc hydroxide Drugs 0.000 description 1
- 229910021511 zinc hydroxide Inorganic materials 0.000 description 1
- 239000011787 zinc oxide 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
- C23C2/26—After-treatment
- C23C2/261—After-treatment in a gas atmosphere, e.g. inert or reducing atmosphere
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B32—LAYERED PRODUCTS
- B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
- B32B15/00—Layered products comprising a layer of metal
- B32B15/01—Layered products comprising a layer of metal all layers being exclusively metallic
- B32B15/012—Layered products comprising a layer of metal all layers being exclusively metallic one layer being formed of an iron alloy or steel, another layer being formed of aluminium or an aluminium alloy
-
- 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
- C21D8/0205—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips of ferrous alloys
-
- 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
- C21D9/46—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for sheet metals
-
- 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
- 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
Abstract
내흑변성 및 표면외관이 우수한 용융아연합금 도금강판 및 그 제조방법이 개시된다. 본 발명의 일 측면인 내흑변성 및 표면외관이 우수한 용융아연합금 도금강판은 소지 강판; 상기 소지 강판 상에 형성된 Al-Zn-MgZn2 3원 공정조직을 기지조직으로 하여, 상기 기지조직 내에 Zn-MgZn2 2원 공정조직이 분산되어 있는 하부 금속조직부; 및 상기 하부 금속조직부 상에 형성된, Zn 단상조직을 기지조직으로 하는 상부 금속조직부를 포함하고, 상기 상부 금속조직부 최표면은 Zn 단상조직이 면적 점유율로 80% 이상을 차지한다.Disclosed is a hot-dip galvanized steel sheet excellent in weathering resistance and surface appearance and a method for producing the same. A hot-dip galvanized steel sheet excellent in weatherability and surface appearance, which is one aspect of the present invention, The hold plate formed on the Al-Zn-MgZn 2 3 won by a process known as tissue organization, Zn-MgZn 2 2 won process organization bottom which is dispersed in the base metal jojikbu tissue; And an upper metal structure portion having a Zn single phase structure as a base structure formed on the lower metal structure portion, wherein the uppermost surface of the upper metal structure portion occupies 80% or more of the area occupied by the Zn single phase structure.
Description
본 발명은 건축자재, 가전제품 및 자동차 부품 등에 사용되는 용융아연합금 도금강판 및 그 제조방법에 관한 것이다.
The present invention relates to a hot-dip galvanized steel sheet used for building materials, household appliances and automobile parts, and a method of manufacturing the same.
아연 도금법은 부식전위가 철보다 낮은 아연을 강판에 부착하는 강판의 내부식성 향상기법이다. 산화 분위기에서 철보다 빠른 아연의 부식을 유도하여 철의 부식을 억제하며 내식성 및 경제성이 우수한 고내식 특성을 갖는 강재를 제조하는데 널리 사용되고 있다. 특히, 용융된 아연에 강재를 침지하여 도금층을 형성하는 용융아연 도금강판은 전기아연 도금강판에 비해 제조공정이 단순하고, 제품가격이 저렴하여 건축자재, 가전제품 및 자동차 부품 등의 산업전반에 걸쳐 그 수요가 증가하고 있다.
The zinc plating method is a technique for improving the corrosion resistance of a steel sheet in which zinc having a lower corrosion potential than iron is attached to the steel sheet. It is widely used to produce steels with high corrosion resistance and excellent corrosion resistance and economical efficiency by inducing corrosion of zinc faster than iron in an oxidizing atmosphere to suppress corrosion of iron. Particularly, the hot-dip galvanized steel sheet which forms the plating layer by immersing the steel into the molten zinc has a simpler manufacturing process than the galvanized steel sheet and has a low product price, and thus is widely used in the fields of building materials, household appliances, The demand is increasing.
아연도금재의 방식기구를 조금 더 자세히 설명하면, 아연이 도금된 용융아연 도금강판은 부식환경에 노출되었을 때 철보다 산화환원전위가 낮은 아연이 먼저 부식되어 강판의 부식이 억제되는 희생방식(Sacrificial Corrosion Protection)의 특성을 가지며, 이와 더불어 도금층의 아연이 산화되면서 강판 표면에 치밀한 부식생성물을 형성시켜 산화 분위기로부터 강재를 차단함으로써 강판의 내부식성을 향상시킨다. 그러나, 산업 고도화에 따른 대기오염의 증가 및 부식환경의 악화가 증가하고 있고, 자원 및 에너지 절약에 대한 엄격한 규제로 인해 종래의 아연 도금강판 보다 더 우수한 내식성을 갖는 강재 개발의 필요성이 높아지고 있다.
A more detailed explanation of the corrosion mechanism of the zinc plating material is that the zinc-plated hot-dip galvanized steel sheet is subjected to a sacrificial corrosion method in which zinc, which is lower in redox potential than iron is firstly corroded, Protection is also provided. In addition, zinc in the plating layer is oxidized to form a dense corrosion product on the surface of the steel sheet, thereby improving the corrosion resistance of the steel sheet by blocking the steel from the oxidizing atmosphere. However, the increase in the air pollution and deterioration of the corrosive environment due to the industrial advancement are increasing, and due to the strict regulations on the resource and energy saving, there is a growing need for the development of steels having better corrosion resistance than the conventional zinc plated steel sheets.
그 일환으로 아연 가격의 상승으로 인해 도금원료의 사용량을 줄이면서 내식성을 향상시키고자 하는 산업계의 수요가 꾸준히 증가하고 있어, 최근 아연도금욕에 알루미늄(Al) 및 마그네슘(Mg) 등의 원소를 첨가하여 강재의 내식성을 향상시키는 아연합금계 도금강판 제조기술의 연구가 다양하게 진행되어 왔다.
As a result, the demand of the industry to increase the corrosion resistance while reducing the amount of the plating material is steadily increasing due to the increase of the zinc price. Recently, the addition of the aluminum (Al) and the magnesium (Mg) There have been various studies on the manufacturing technology of the steel plate of the alloy steel which improves the corrosion resistance of the steel material.
예컨대, 특허문헌 1에서는 3~17중량%의 Al 및 1~5중량%의 Mg을 함유하는 도금욕을 이용하여 제조한 용융아연합금 도금강판 제조방법을 개시하고 있으며, 특허문헌 2 내지 4에서는 상기와 동일한 조성을 갖는 도금욕 내에 각종의 첨가원소를 배합하거나 제조조건을 규제하는 것에 의해 내식성 및 제조특성을 개선시킨 용융아연합금 도금방법을 개시하고 있다.
For example, Patent Document 1 discloses a method of producing a hot-dip galvanized steel sheet using a plating bath containing 3 to 17 wt% of Al and 1 to 5 wt% of Mg. In Patent Documents 2 to 4, Discloses a hot-dip galvanizing method in which various additives are mixed in a plating bath having the same composition as the hot-dip galvanizing bath and the corrosion resistance and manufacturing characteristics are improved by regulating the production conditions.
그러나, 도금층 내 Mg과 Al의 함량이 증가 할수록 합금도금층 미세조직 중 미세경도가 높은 MgZn2의 영향으로 도금층의 경도가 증가하게 되며, 이러한 도금층의 경도 증가 현상은 프레스 성형시 금형과 도금층 마찰에 의한 도금층 박리를 억제하여 금형의 오염을 줄이는 장점이 있으나, 90˚ 이상의 굽힘가공 및 심한 프레스 가공시 도금층 표면에 크랙을 유발하여, 가공부의 외관 및 내식성을 저하시키는 문제점이 있었다.
However, as the content of Mg and Al in the plating layer increases, the hardness of the plating layer increases due to the effect of MgZn 2 , which is high in microhardness in the microstructure of the alloy plating layer. The increase in hardness of the plating layer is caused by the friction between the metal mold and the plating layer There is an advantage of suppressing the peeling of the plating layer to reduce the contamination of the mold. However, there is a problem in that the surface of the plating layer is cracked during the bending process of 90 DEG or more and the severe pressing process, and the appearance and corrosion resistance of the processed portion are lowered.
상술한 도금층 품질특성 저하 문제를 해결하기 위하여 합금도금층을 형성시키는 제조 프로세스 조건을 조절하여 도금층의 미세조직을 제어하는 연구가 수행되었다.
In order to solve the above-mentioned problem of lowering the quality of the plating layer, researches have been conducted to control the microstructure of the plating layer by adjusting the manufacturing process conditions for forming the alloy plating layer.
예컨대, 특허문헌 5에서는 4~10중량% 및 1~4중량%를 포함하는 Zn-Al-Mg 도금층을 강판 표면에 형성함에 있어 도금욕 온도 및 냉각속도를 조절하여 해당 도금층이 Al/Zn/Zn2Mg의 3원 공정조직 및 초정 Al상이 혼재되고, Zn11Mg2상을 함유하지 않는 금속조직을 형성하여 내식성 및 표면외관 특성을 향상시키는 기술을 개시하고 있다.
For example, in Patent Document 5, when a Zn-Al-Mg plating layer containing 4 to 10% by weight and 1 to 4% by weight is formed on the surface of a steel sheet, the plating bath temperature and cooling rate are controlled so that the plating layer is Al / Zn / Zn 2 Mg ternary structure and a preliminary Al phase are mixed and a metal structure not containing Zn 11 Mg 2 phase is formed to improve the corrosion resistance and surface appearance characteristics.
또한, 특허문헌 6에서는 도금층 내에 형성된 Mg계 금속간 화합물의 미세조직을 제어하기 위하여 3중량%이하의 미량원소를 첨가한 후 도금층 냉각속도를 5℃/sec 이상으로 조절하였고 금속간 화합물 조직의 사이즈를 균일하게 분산시킴으로써 가공성을 개선시키는 기술을 개시하고 있다.
In addition, in Patent Document 6, in order to control the microstructure of the Mg intermetallic compound formed in the plating layer, after adding trace elements of 3 wt% or less, the cooling rate of the plating layer was controlled to 5 DEG C / sec or more, To thereby improve workability.
또한, 특허문헌 7에서는 1~60중량% 및 1~10중량%를 포함하는 Zn-Al-Mg 합금계 도금강판을 제조함에 있어서, 도금층 냉각속도를 (0.1 x 도금욕 온도 - 10) (℃/sec) 이상으로 급냉하여 Zn-Mg계 금속간 화합물상 및 Al-Mg계 금속간 화합물의 사이즈를 10nm~1㎛ 이하로 조절하여 합금도금강판의 가공성 및 가공부 내식성을 향상시키는 기술을 개시하고 있다.
In Patent Literature 7, the coating layer cooling rate is (0.1 x plating bath temperature - 10) (° C / ° C) in producing a Zn - Al - Mg alloy plated steel sheet containing 1 to 60 wt% and 1 to 10 wt% sec or more so as to adjust the size of the Zn-Mg intermetallic compound phase and the Al-Mg intermetallic compound to 10 nm to 1 탆 or less to improve the processability and corrosion resistance of the alloy-plated steel sheet .
그러나, Mg 및 Al 함유 합금도금층의 미세조직은 대부분 Zn/MgZn2/Al 3원공정상과 Zn/MgZn2 2원공정상 등 금속간 화합물로 이루어져 있으며, 합금도금층의 표면조직 또한 상기 금속간 화합물 조직이 대부분을 이루고 있다. 금속간 화합물 내 Mg과 Al은 Zn보다 흡습성이 강하여 습윤분위기에 노출되었을 때에는 표면 조직이 100% Zn 단상으로 이루어진 일반 아연용융도금재(GI)에 비하여 표면 색상이 흑색으로 변하는 변색이 쉽게 발생하는 문제점이 있었다.
However, the microstructure of the alloys, the coating layer of Mg and Al is made up mostly Zn / MgZn 2 / Al 3 won process phase and the Zn / MgZn 2 2 won process phase such as intermetallic compound, the alloy plating layer surface texture also the intermetallic compound The organization is the majority. Mg and Al in the intermetallic compound are more hygroscopic than Zn, and when exposed to a wetting atmosphere, discoloration of the surface color changes to black compared to a general zinc hot-dip coating (GI) composed of 100% Zn single phase .
본 발명의 일 측면은 Zn-Al-Mg계 용융아연합금 도금욕을 이용하여 제조된 내흑변성 및 표면외관이 우수한 용융아연합금 도금강판 및 그 제조방법을 제공하고자 하는 것이다.
One aspect of the present invention is to provide a hot-dip galvanized steel sheet having excellent weatherability and surface appearance, which is produced by using a Zn-Al-Mg based hot-dip galvanizing bath and a method of manufacturing the same.
본 발명의 일 측면은, 소지 강판; 상기 소지 강판 상에 형성된 Al-Zn-MgZn2 3원 공정조직을 기지조직으로 하여, 상기 기지조직 내에 Zn-MgZn2 2원 공정조직이 분산되어 있는 하부 금속조직부; 및 상기 하부 금속조직부 상에 형성된, Zn 단상조직을 기지조직으로 하는 상부 금속조직부를 포함하고, 상기 상부 금속조직부 최표면의 Zn 단상조직 점유 면적율이 80% 이상인 내흑변성 및 표면외관이 우수한 용융아연합금 도금강판을 제공한다.
According to an aspect of the present invention, The hold plate formed on the Al-Zn-MgZn 2 3 won by a process known as tissue organization, Zn-MgZn 2 2 won process organization bottom which is dispersed in the base metal jojikbu tissue; And an upper metal structure portion formed on the lower metal structure portion and having a Zn single phase structure as a base structure, wherein the upper surface of the upper metal structure has a black single-phase structure occupancy rate of 80% or more, Thereby providing a plated steel sheet.
또한, 본 발명의 다른 일 측면은, 중량%로, Al: 0.5~5.0%, Mg: 0.5~5%, 잔부 Zn 및 불가피한 불순물을 포함하고, Al+Mg: 1.5~7%인 용융아연합금 도금욕을 준비하는 단계; 소지강판을 상기 용융아연합금 도금욕에 침지하여 용융아연합금 도금강판을 제조하는 단계; 및 상기 용융아연합금 도금강판을 가스와이핑한 후, 13℃/sec 이상의 냉각속도로 360~420℃의 온도까지 냉각하는 단계를 포함하는 내흑변성 및 표면외관이 우수한 용융아연합금 도금강판의 제조방법을 제공한다.
Another aspect of the present invention is a hot-dip galvanized steel sheet comprising 0.5 to 5.0% of Al, 0.5 to 5% of Mg, the balance of Zn and unavoidable impurities, and a molten zinc alloy plating containing Al and Mg in an amount of 1.5 to 7% Preparing a bath; Preparing a hot-dip galvanized steel sheet by immersing the pre-coated steel sheet in the hot-dip galvanizing bath; And cooling the molten zinc alloy plated steel sheet to a temperature of 360 to 420 占 폚 at a cooling rate of 13 占 폚 / sec or more after gas wiping the molten zinc alloy plated steel sheet, and a method for producing a hot- .
덧붙여, 상기한 과제의 해결 수단은, 본 발명의 특징을 모두 열거한 것은 아니다. 본 발명의 다양한 특징과 그에 따른 장점 및 효과는 하기의 구체적인 실시형태를 참조하여 보다 상세하게 이해될 수 있을 것이다.
In addition, the solution of the above-mentioned problems does not list all the features of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS The various features and advantages and effects of the present invention will become more fully understood with reference to the following specific embodiments.
본 발명에 따르면, 표면 거칠기 값이 낮고, 광택도가 높을 뿐만 아니라, 내흑변성이 우수한 용융아연합금 도금강판을 제공할 수 있다.
INDUSTRIAL APPLICABILITY According to the present invention, it is possible to provide a hot-dip galvanized steel sheet having a low surface roughness value, high gloss, and excellent black weather resistance.
또한, 본 발명에 따르면, 새로운 유기 표면처리 용액을 개발하는 번거로움 없이 기존의 용융아연 도금강판용(GI용) 후처리 용액 사용이 가능하여, 결과적으로 도금층의 전체적인 내식성을 향상시킬 수 있다.
Further, according to the present invention, it is possible to use a post-treatment solution for a conventional hot dip galvanized steel sheet (GI) without the hassle of developing a new organic surface treatment solution, and as a result, the overall corrosion resistance of the plating layer can be improved.
도 1은 본 발명의 실시예에 따른 냉각속도별 용융아연합금 도금강판의 단면의 미세조직을 관찰한 것이다.
도 2는 본 발명의 실시예에 따른 냉각속도별 용융아연합금 도금강판 최표면의 미세조직을 관찰한 것이다.
도 3은 본 발명의 실시예에 따른 냉각속도별 용융아연합금 도금강판의 표면을 관찰한 사진이다.
도 4는 본 발명의 실시예에 따라 제조된 용융 아연합금 도금강판의 후처리 후, 염수분무시험을 수행한 후, 그 표면을 관찰한 사진이다.FIG. 1 is a view showing the microstructure of a cross-section of a hot-dip galvanized steel sheet for each cooling rate according to an embodiment of the present invention.
FIG. 2 is a graph showing the microstructure of the outermost surface of the hot-dip zinc-plated steel sheet according to the cooling rate according to the embodiment of the present invention.
3 is a photograph showing the surface of a hot-dip galvanized steel sheet at a cooling rate according to an embodiment of the present invention.
4 is a photograph showing the surface of a hot-dip galvanized steel sheet produced according to an embodiment of the present invention after a post-treatment of a salt water spray test.
본 발명자들은 상술한 종래기술의 문제점을 해결하기 위하여, 용융아연합금 도금강판의 내흑변성 및 표면외관을 향상시킬 수 있는 방법에 대하여 연구하던 중, 용융상태의 도금층 냉각시 냉각 종료온도 및 냉각속도를 제어하여 도금층의 최표면에 면적점유율 80% 이상의 Zn 단상조직을 형성시킴으로써 용융아연합금 도금강판의 내흑변성 및 표면외관을 향상시킬 수 있다는 점을 인지하고 본 발명을 제안하게 되었다.
DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention In order to solve the problems of the prior art described above, the inventors of the present invention have been studying a method of improving the weathering resistance and surface appearance of a hot dip galvanized steel sheet, It is possible to improve the weathering resistance and surface appearance of the hot-dip galvanized steel sheet by forming a Zn single-phase structure having an area occupying ratio of 80% or more on the outermost surface of the plating layer.
이하, 본 발명에 대하여 상세히 설명한다.
Hereinafter, the present invention will be described in detail.
먼저, 본 발명에 따른 내흑변성 및 표면외관이 우수한 용융아연합금 도금강판의 제조방법에 대하여 상세히 설명한다.
First, a method for manufacturing a hot-dip galvanized steel sheet having excellent black marking and surface appearance according to the present invention will be described in detail.
본 발명의 일측면인 내흑변성 및 표면외관이 우수한 용융아연합금 도금강판의 제조방법은 중량%로, Al: 0.5~5.0%, Mg: 0.5~5%, 잔부 Zn 및 불가피한 불순물을 포함하고, Al+Mg: 1.5~7%인 용융아연합금 도금욕을 준비하는 단계; 소지강판을 상기 용융아연합금 도금욕에 침지하여 용융아연합금 도금강판을 제조하는 단계; 및 상기 용융아연합금 도금강판을 가스와이핑한 후 냉각하는 단계를 포함한다.
A method for producing a hot-dip galvanized steel sheet excellent in weathering resistance and surface appearance, which is one aspect of the present invention, comprises 0.5 to 5.0% of Al, 0.5 to 5% of Mg, the balance of Zn and unavoidable impurities, + Mg: 1.5 to 7%; Preparing a hot-dip galvanized steel sheet by immersing the pre-coated steel sheet in the hot-dip galvanizing bath; And cooling the molten zinc alloy plated steel sheet by gas wiping and then cooling the molten zinc alloy plated steel sheet.
용융아연합금 Molten zinc alloy 도금욕을Plating bath 준비하는 단계 Steps to prepare
본 발명에 이용되는 용융아연합금 도금욕은 중량%로, Al: 0.5~5.0%, Mg: 0.5~5%, 잔부 Zn 및 불가피한 불순물을 포함하고, Al+Mg: 1.5~7%의 관계를 만족함이 바람직하다.
The molten zinc alloy plating bath used in the present invention preferably contains 0.5 to 5.0% of Al, 0.5 to 5% of Mg, the balance of Zn and unavoidable impurities, and satisfies the relationship of Al + Mg: 1.5 to 7% .
상기 용융아연합금 도금욕 내의 성분 중 Mg은 도금층의 내식성 향상에 매우 중요한 역할을 하는 원소로서, 도금층 내부에 함유된 Mg은 가혹한 부식 환경에서 내식성의 향상 효과가 적은 아연산화물계 부식생성물의 성장을 억제하고, 치밀하며 내식성 향상 효과가 큰 아연수산화물계 부식생성물을 도금층 표면에서 안정화시킨다.
Mg contained in the plating layer plays an important role in improving the corrosion resistance of the plating layer. Mg contained in the plating layer inhibits the growth of zinc oxide-based corrosion products, which is less effective in improving the corrosion resistance in a severe corrosive environment. And stabilizes the zinc hydroxide based corrosion product, which is dense and has a large effect of improving the corrosion resistance, on the surface of the plating layer.
상기 Mg의 함량이 0.5중량% 미만인 경우에는 Zn-Mg계 화합물 생성에 의한 내식성 향상효과가 충분치 않으며, 반면 5중량%를 초과하는 경우에는 내식성 향상효과가 포화될 뿐만 아니라, Mg 산화성 드로스가 도금욕 욕면에 급증하는 문제가 있다. 따라서, 본 발명에서는 도금욕 내의 Mg 함량은 0.5~5중량%로 제어함이 바람직하다.
If the content of Mg is less than 0.5% by weight, the effect of improving the corrosion resistance due to the formation of the Zn-Mg based compound is insufficient. On the other hand, if the content exceeds 5% by weight, the effect of improving the corrosion resistance is saturated, There is a problem of surging in the face. Therefore, in the present invention, the Mg content in the plating bath is preferably controlled to 0.5 to 5 wt%.
상기 Al은 Mg을 첨가한 용융아연합금 도금욕 내에서 Mg 산화반응에 의해 발생하는 드로스를 감소시키기 위한 목적으로 첨가하며, Al은 Zn 및 Mg와 조합하여 도금강판의 내부식성을 향상시키는 역할도 한다.
The Al is added for the purpose of reducing the dross generated by the Mg oxidation reaction in the hot dip galvanizing bath containing Mg and Al is combined with Zn and Mg to improve the corrosion resistance of the coated steel do.
상기 Al의 함량이 0.5중량% 미만인 경우에는 Mg 첨가에 의한 도금욕 표층부 산화를 방지하는 효과가 미흡하고, 내식성 향상 효과가 적다. 반면, 상기 Al의 함량이 5.0중량%를 초과하는 경우에는 도금욕에 침지된 강판의 Fe 용출량이 급증하여 Fe 합금계 드로스가 형성되고, 더욱이 도금층의 용접성이 저하되는 문제가 발생한다. 따라서, 본 발명에서는 도금욕 내의 Al 함량을 0.5~5.0중량%로 제어함이 바람직하다.
When the content of Al is less than 0.5% by weight, the effect of preventing the oxidation of the surface layer of the plating bath by Mg addition is insufficient and the effect of improving the corrosion resistance is small. On the other hand, when the content of Al exceeds 5.0% by weight, the amount of Fe elution in the steel sheet immersed in the plating bath is rapidly increased, resulting in the formation of Fe alloy system dross, and furthermore, the weldability of the plating layer is deteriorated. Therefore, in the present invention, it is preferable to control the Al content in the plating bath to 0.5 to 5.0 wt%.
한편, 상기 Al과 Mg은 모두 도금층의 내식성을 향상시키는 원소로서 이들 원소의 합이 증가할수록 내식성은 향상될 수 있다. 그러나, 도금욕 중 Al 및 Mg 함량의 합이 1.5중량% 미만인 경우, 내식성 향상 효과가 미미하며, 상기 Al 및 Mg 함량의 합이 7.0중량%를 초과하게 되면 내식성 향상 효과가 포화될 뿐만 아니라, 도금층의 경도가 상승하여 가공 크랙(crack) 발생이 촉진되고, 용접성 및 도장성이 열화되거나 처리방법의 개선을 필요로 하는 등의 문제점이 있다. 따라서, 본 발명에서는 도금욕 내의 Al 및 Mg 함량의 합을 1.5~7.0중량%로 제어함이 바람직하다.
On the other hand, both Al and Mg improve the corrosion resistance of the plating layer. As the sum of these elements increases, the corrosion resistance can be improved. However, when the sum of the contents of Al and Mg in the plating bath is less than 1.5% by weight, the effect of improving corrosion resistance is insignificant. If the sum of the contents of Al and Mg exceeds 7.0% by weight, the effect of improving the corrosion resistance is saturated, The hardness of the steel is increased and the occurrence of cracks is promoted, and the weldability and paintability are deteriorated and the treatment method is required to be improved. Therefore, in the present invention, it is preferable to control the sum of the contents of Al and Mg in the plating bath to 1.5 to 7.0% by weight.
도금강판을 제조하는 단계Step of producing a coated steel sheet
용융아연합금 도금욕 내에서 소지강판을 침지하여 도금을 행할 시, 통상의 용융아연합금 도금시의 도금욕 온도를 적용할 수 있으며, 바람직하게는 430~480℃ 범위의 도금욕 내에서 도금을 수행할 수 있다.
When the base steel sheet is immersed in the molten zinc alloy plating bath to perform plating, the plating bath temperature at the time of the ordinary hot-dip galvanizing can be applied, and preferably, the plating is carried out in a plating bath at 430 to 480 ° C can do.
한편, 일반적으로 도금욕 내의 성분 중 Al의 함량이 높아지면 융점이 높아지므로 도금욕의 온도를 증가시켜야 한다. 그러나, 도금욕의 온도가 높아지면 모재 강판 및 도금욕 내부 설비가 침식되어 장비의 수명단축을 초래할 뿐만 아니라, 도금욕 내 Fe 합금 드로스가 증가하여 도금재의 표면이 불량해지는 문제가 있다.
On the other hand, generally, when the content of Al in the components in the plating bath becomes higher, the melting point becomes higher, so the temperature of the plating bath must be increased. However, if the temperature of the plating bath is increased, the base steel sheet and the plating bath internal equipment are eroded to shorten the service life of the equipment. In addition, there is a problem that the surface of the plating material becomes poor due to an increase in Fe alloy dross in the plating bath.
그러나, 본 발명에서는 Al의 함량을 0.5~5.0중량%로 비교적 낮게 제어하므로, 도금욕의 온도를 높게 설정할 필요가 없으며, 통상의 도금욕 온도를 적용함이 바람직하다.
However, in the present invention, since the content of Al is controlled to be relatively low as 0.5 to 5.0 wt%, it is not necessary to set the temperature of the plating bath at a high temperature, and it is preferable to apply the ordinary plating bath temperature.
가스와이핑Gas wiping 및 냉각하는 단계 And cooling step
상기 도금 후 가스와이핑 처리를 통해 도금 부착량을 조정한다. 원활한 냉각속도 조절 및 도금층 표면산화를 방지하기 위하여 상기 와이핑 가스는 질소 또는 아르곤 가스를 사용하는 것이 바람직하며 가스의 온도는 -20℃~상온(25℃)의 범위를 갖는 것이 바람직하다. 한편, 상기 가스와이핑은 도금 부착량을 조정하기 위한 것으로 그 방법은 특별히 한정되는 것은 아니다.
The plating adhesion amount is adjusted through the post-plating gas wiping treatment. It is preferable that the wiping gas is nitrogen or argon gas and the temperature of the gas is in the range of -20 ° C to room temperature (25 ° C) in order to smoothly control the cooling rate and prevent oxidation of the surface of the plating layer. On the other hand, the gas wiping is for adjusting the plating adhesion amount, and the method is not particularly limited.
상기 냉각시 냉각 종료온도는 360~420℃인 것이 바람직하다. 도금층 내 금속간 화합물은 서로 상이한 응고온도를 가지며, 예컨대, Zn 단상은 420℃, Zn/MgZn2 2원공정상 및 Zn/Al/MgZn2 3원공정상은 360℃의 응고온도를 나타낸다. 따라서, 냉각 종료온도가 상기의 범위를 가질 경우, 도금층 내 금속간 화합물 중 응고온도가 가장 높은 Zn 단상만의 표면에서의 급속한 부분 응고를 유도할 수 있다. 한편, 상기 냉각 종료온도 이후 강판의 온도변화는 Zn 단상의 표면 노출량 변화와는 무관하다.
The cooling termination temperature during the cooling is preferably 360 to 420 ° C. Between the metal compound coating layer has a solidification temperature are different from each other, for example, Zn single phase represents the 420 ℃, Zn / MgZn 2 2 won process phase and Zn / Al / MgZn 2 3 won phase coagulation process temperature of 360 ℃. Therefore, when the cooling end temperature is in the above range, rapid partial solidification of the surface of only the Zn single phase having the highest solidification temperature among the intermetallic compounds in the plating layer can be induced. On the other hand, the temperature change of the steel sheet after the cooling end temperature is independent of the change of the surface exposure amount of the Zn single phase.
한편, 일반적인 용융도금 공정에서는 도금 후 강판 냉각시, 강판 표면의 온도는 도금층 표면과 대비하여 더 낮기 때문에 응고온도가 가장 높은 미세조직, 예컨대 Zn 단상은 강판의 표면에서 석출하여 도금면 수직방향으로 성장하게 된다. 그러나, 본 발명에서는 도금 후 강판 냉각시 13℃/sec 이상의 급냉을 행하기 때문에, Zn 단상이 강판의 표면에서 석출되기 이전에 응고되며, 응고된 Zn 단상은 용융 상태의 도금층의 상부로 부유하여 상부 금속조직부를 형성하게 된다.
On the other hand, in a general hot dip galvanizing process, the temperature of the surface of the steel sheet is lower than that of the surface of the coating layer during cooling of the steel sheet after plating, so that the microstructure having the highest coagulation temperature such as Zn single phase precipitates on the surface of the steel sheet, . However, in the present invention, since quenching is carried out at a rate of 13 ° C / sec or more during cooling of the coated steel sheet, the Zn single phase solidifies before being deposited on the surface of the steel sheet, and the coagulated Zn single phase floats to the upper portion of the molten- Thereby forming a metal texture portion.
도 1를 참조하여 보면, 상기 냉각속도가 4.8℃/s인 경우, 상부 금속조직부 및 하부 금속조직부의 구분 없이 Al-Zn-MgZn2 3원 공정조직(100), Zn-MgZn2 2원 공정조직(200) 및 Zn 단상조직(300)이 균일하게 분포하고 있으나, 상기 냉각속도가 12.1℃/s인 경우, 도금층의 표면에 Zn 단상이 형성되기 시작하였으며, 냉각속도 13℃/s 이상에서는 형성된 Zn 단상이 서로 결합함으로써 하부 금속조직부와 구별되는 상부 금속조직부를 형성함을 알 수 있다.
In reference to FIG. 1, when the cooling rate of 4.8 ℃ / s, the upper metal jojikbu and without distinguishing the underlying metal jojikbu Al-Zn-MgZn 2 3 won step tissue (100), Zn-MgZn 2 2 won step tissue The Zn
한편, 상기 냉각하는 단계에서, 냉각 방법으로는 도금층을 냉각시킬 수 있는 통상의 냉각방법을 이용할 수 있으며, 예컨대 Air jet cooler를 이용하거나 N2 와이핑 또는 water fog 등을 분무함으로써 냉각을 수행할 수 있다.
On the other hand, in the cooling step, as the cooling method, a usual cooling method which can cool the plating layer can be used, and cooling can be performed by using, for example, an air jet cooler or spraying N 2 wiping or water fog have.
이하, 본 발명에 따른 내흑변성 및 표면외관이 우수한 용융아연합금 도금강판에 대하여 상세히 설명한다.Hereinafter, a hot-dip galvanized steel sheet having excellent black weather resistance and surface appearance according to the present invention will be described in detail.
상기 내흑변성 및 표면외관이 우수한 용융아연합금 도금강판은 전술한 방법에 의해 제조된다.
The hot-dip galvanized steel sheet excellent in black weathering and surface appearance is produced by the above-mentioned method.
본 발명의 일 측면인 내흑변성 및 표면외관이 우수한 용융아연합금 도금강판은 소지 강판; 상기 소지 강판 상에 형성된 Al-Zn-MgZn2 3원 공정조직을 기지조직으로 하여, 상기 기지조직 내에 Zn-MgZn2 2원 공정조직이 분산되어 있는 하부 금속조직부; 및 상기 하부 금속조직부 상에 형성된, Zn 단상조직을 기지조직으로 하는 상부 금속조직부를 포함하고, 상기 상부 금속조직부 최표면은 Zn 단상조직이 면적 점유율로 80% 이상을 차지한다.
A hot-dip galvanized steel sheet excellent in weatherability and surface appearance, which is one aspect of the present invention, The hold plate formed on the Al-Zn-MgZn 2 3 won by a process known as tissue organization, Zn-MgZn 2 2 won process organization bottom which is dispersed in the base metal jojikbu tissue; And an upper metal structure portion having a Zn single phase structure as a base structure formed on the lower metal structure portion, wherein the uppermost surface of the upper metal structure portion occupies 80% or more of the area occupied by the Zn single phase structure.
본 발명에서 목적으로 하는 우수한 내흑변성을 얻기 위해서는, 상기 상부 금속조직부 최표면의 Zn 단상조직의 면적점유율을 높게 확보함이 바람직하며, 이는 상술한 바와 같이 도금후 냉각시 냉각 종료온도 및 냉각속도의 영향을 크게 받는다.
In order to obtain the excellent black marking which is the object of the present invention, it is preferable to ensure a high occupancy of the area of the Zn single-phase structure on the outermost surface of the upper metal structure portion. This is because, It is greatly affected.
한편, 도금강판의 표면조도는 프레스 성형할 때의 가공성 향상 및 도장후 선영성에 영향을 미치는 중요한 인자로서 관리가 필요하며, 본 발명 용융아연합금 도금강판의 표면 조도는 0.8㎛ 이하인 것이 바람직하다.
On the other hand, the surface roughness of the coated steel sheet needs to be managed as an important factor influencing the workability in press molding and the post-coat post-coatability, and it is preferable that the surface roughness of the hot-dip galvanized steel sheet of the present invention is 0.8 탆 or less.
이하, 본 발명을 실시예를 통하여 보다 상세하게 설명한다. 그러나, 이러한 실시예의 기재는 본 발명의 실시를 예시하기 위한 것일 뿐 이러한 실시예의 기재에 의하여 본 발명이 제한되는 것은 아니다. 본 발명의 권리범위는 특허청구범위에 기재된 사항과 이로부터 합리적으로 유추되는 사항에 의해 결정되는 것이기 때문이다.
Hereinafter, the present invention will be described in more detail with reference to examples. However, the description of these embodiments is intended only to illustrate the practice of the present invention, but the present invention is not limited thereto. The scope of the present invention is determined by the matters set forth in the claims and the matters reasonably inferred from them.
(( 실시예Example 1) One)
강판의 두께, 폭 및 길이가 각각 0.8 mm x 120 mm x 200 mm인 냉연강판을 아세톤에 침지시킨 상태로 초음파로 세척하여 표면의 이물질과 기름을 제거하여 시편을 준비한 후, 소둔하였다. 상기 소둔은 분위기 가스가 수소 10% 및 질소 90%로 구성된 환원분위기에서 진행하였으며, 소둔 열처리 사이클은 요구되는 기계적 성질에 적합하게 700~820℃로 하였다.
The cold-rolled steel sheet having thickness, width and length of 0.8 mm x 120 mm x 200 mm was immersed in acetone and ultrasonically cleaned to remove foreign matter and oil on the surface to prepare specimens and then annealed. The annealing was carried out in a reducing atmosphere composed of 10% of hydrogen and 90% of nitrogen, and the annealing heat treatment cycle was set to 700 to 820 캜 in accordance with the required mechanical properties.
이후, 환원분위기에서 열처리된 시편을 준비된 2중량%의 Al 및 3중량%의 Mg이 함유된 합금용융도금욕 용탕에 약 5초간 침적 후 끌어올려 가스 와이핑하여 합금도금층의 부착량을 편면기준 70g/m2으로 조절하였다. 강판의 냉각속도를 관찰하기 위하여 강판에 열전대(Thermocouple)를 접촉시켜 냉각 과정 중 강판의 미세온도 변화를 모니터링 하였다. 시험편의 냉각속도에 따른 도금층 특성 변화를 관찰하기 위하여 냉각가스의 유량은 200~1400l/m3으로 조절하였고, 동일한 냉각가스 유량 하에서 강판의 이동속도를 100~500 mm/s로 조절하였다. 한편, 냉각 종료온도는 모든 시편에서 420℃로 일정하게 하였다.
Thereafter, the specimens heat-treated in a reducing atmosphere were immersed in a prepared molten alloy for molten steel containing 2 wt% of Al and 3 wt% of Mg for about 5 seconds and then gas-wiped by gas wiping so that the adhesion amount of the alloy plated layer was 70 g / m < 2 & gt ;. In order to observe the cooling rate of the steel sheet, a thermocouple was brought into contact with the steel sheet to monitor the micro temperature change of the steel sheet during the cooling process. The flow rate of the cooling gas was adjusted to 200 ~ 1400 l / m 3 and the moving speed of the steel sheet was adjusted to 100 ~ 500 mm / s under the same cooling gas flow rate. On the other hand, the cooling termination temperature was constant at 420 ° C in all specimens.
이후, 합금 도금재 표면 도금층의 미세조직과 광택도, 표면 조도 및 내습윤성 등의 물성을 평가하고, 그 결과를 하기 표 1에 나타내었다.
Then, the microstructure of the surface plated layer of the alloy plating material, physical properties such as gloss, surface roughness and wettability were evaluated, and the results are shown in Table 1 below.
한편, 광택도는 광택계(Glossmeter REF-260)으로 측정하였으며, 표면 조도는 3차원 표면형상특정기(WYKO NT8000, Veeco)로 측정하였다.
The gloss was measured with a gloss meter (Glossmeter REF-260), and the surface roughness was measured with a three-dimensional surface shape specifier (WYKO NT8000, Veeco).
한편, 내습윤성을 평가하기 위한 습윤테스트 챔버의 온도는 45℃였고, 습도는 95 %였다. Zn 응고 완료온도까지의 냉각속도를 변화시킨 각각의 시편을 습윤챔버에 장입 전과 습윤챔버 장입 후 200시간 경과시 도금층 표면의 색차 변화를 측정하였다. 색차 변화량(ΔE)은 수학식 1을 이용하여 구하였다.
On the other hand, the temperature of the wet test chamber for evaluating the wettability was 45 캜, and the humidity was 95%. The change in the color difference of the surface of the plating layer was measured before charging each specimen with the cooling rate up to the Zn solidification completion temperature into the wet chamber and 200 hours after the wet chamber was charged. The color difference variation amount? E was obtained using Equation (1).
[수학식 1][Equation 1]
(L1: 습윤챔버 장입 전 백색도, L2: 습윤챔버 장입 후 200시간 경과시 백색도 a1: 습윤챔버 장입 전 적색도, a2: 습윤챔버 장입 후 200시간 경과시 적색도, b1: 습윤챔버 장입 전 황색도, b2: 습윤챔버 장입 후 200시간 경과시 황색도)
(L 1: wet chamber contents before the whiteness, L 2: Fig before charging the wet chamber red, a 2:: wet chamber charged after whiteness a 1 hour has elapsed 200 hours redness in wet chamber charged after lapse of 200 hours, b 1: Wet B 2 : yellowness after 200 hours after charging of the wetting chamber)
(℃/sec)Cooling rate
(° C / sec)
상기 표 1에 나타낸 바와 같이, 시편의 냉각속도가 증가함에 도금층의 최표면에 Zn 단상조직의 면적 점유율이 증가함을 알 수 있으며, 냉각속도가 13℃/s 이상인 경우, 도금층의 최표면에 Zn 단상조직 면적점유율이 80% 이상인 것을 확인할 수 있었다. 한편, 도 2는 본 발명의 실시예에 따른 냉각속도별 용융아연합금 도금강판의 최표면의 미세조직을 관찰한 것으로, 도 2의 (a) 내지 (c)는 각각 비교예 1, 3 및 4를, 도2의 (d) 내지 (f)는 각각 발명예 1 내지 3을 나타낸다. 한편, 100은 Zn/Al/MgZn2 3원공정조직, 200은 Zn/MgZn2 2원공정조직, 300은 100% Zn으로 이루어진 Zn 단상조직을 나타내며, 400은 연속적으로 형성된 Zn 단상조직을 나타낸다.
As shown in Table 1, when the cooling rate of the specimen increases, the occupancy of the Zn single phase structure increases at the outermost surface of the plating layer. When the cooling rate is 13 ° C / s or higher, Zn It was confirmed that the occupancy rate of the single-phase tissue area was 80% or more. 2 (a) to 2 (c) are cross-sectional views showing the results of Comparative Examples 1, 3, and 4, respectively, of the microstructure of the outermost surface of the molten zinc alloy plated steel sheet according to the embodiment of the present invention. 2 (d) to 2 (f) show inventive examples 1 to 3, respectively. On the other hand, 100 denotes a Zn single phase tissue consisting of a Zn / Al / MgZn 2 3 won process organization, 200 Zn / MgZn 2 2 won process organization, and 300 are 100% Zn, 400 denotes a Zn single phase structure formed in succession.
한편, 도금강판의 표면외관과 관련하여, 도금 후 냉각속도가 증가함에 따라 도금층 표면의 광택도가 증가하며, 반면에 표면조도는 감소함을 확인할 수 있었다. 이러한 도금층 표면외관 향상은 도금층 최표면의 Zn 단상조직 면적점유율이 80 % 이상일 때 두드러지게 나타났다. 한편, 도 3은 본 발명의 실시예에 따른 냉각속도별 용융아연합금 도금강판의 표면을 관찰한 사진으로, 도 3의 (a) 내지 (c)는 각각 비교예 1, 비교예 4 및 발명예 3에 따른 용융아연합금 도금강판의 표면을 관찰한 사진이다.
On the other hand, with respect to the surface appearance of the coated steel sheet, it was confirmed that as the cooling rate after plating increased, the gloss of the surface of the coating layer increased, while the surface roughness decreased. The appearance improvement of the surface of the plating layer was prominent when the occupancy rate of the single phase structure of the Zn on the outermost surface of the plating layer was 80% or more. 3 (a) to 3 (c) are photographs showing the surface of a hot dip galvanized steel sheet for each cooling rate according to an embodiment of the present invention, 3 is a photograph of the surface of a hot-dip galvanized steel sheet according to the present invention.
한편, 도금강판의 내습윤성과 관련하여, Zn 응고 완료온도까지의 냉각속도가 증가함에 따라 습윤테스트 후 도금층 표면 색차 변화 값이 감소함을 알 수 있었다. 냉각속도가 13℃/s 이상일 때 기존 용융아연도금재(ΔE=3.3)와 유사한 색차변화 값을 보였다. 냉각속도가 낮은 시편, 즉 표면에 Al 및 Mg 함유 금속간 화합물의 표면 노출량이 많은 시편의 경우, Zn 대비 Al 및 Mg의 높은 흡습성으로 인해 습윤테스트 이후 도금층 표면의 변색도가 높게 나타났다.
On the other hand, with respect to the wettability of the coated steel sheet, it was found that the change in color difference on the surface of the plating layer after the wet test decreased as the cooling rate to the Zn solidification completion temperature increased. When the cooling rate was higher than 13 ℃ / s, the color difference was similar to that of the conventional hot dip galvanizing material (ΔE = 3.3). In the case of specimens with a low cooling rate, ie, the surface of Al and Mg containing intermetallic compounds on the surface was large, the surface discoloration of the surface of the plating layer after the wet test was high due to the high hygroscopicity of Al and Mg compared to Zn.
(( 실시예Example 2) 2)
도금층 표면의 백청 발생량을 평가하기 위해 상기 실시예 1에 따라 제작된 용융아연합금 도금강판을 후처리하고, 상기 후처리된 용융아연합금 도금강판을 염수분무시험기에 장입한 후 염수분무시험 공인규격(KS-C-0223)으로 100시간 부식촉진시험을 수행한 후 도금층 표면의 백청 발생 경향을 관찰하였다.
To evaluate the amount of white rust on the surface of the plating layer, the hot-dip zinc-plated steel sheet prepared in Example 1 was post-treated, the post-treated hot-dip galvanized steel sheet was loaded into a salt spray tester, KS-C-0223) for 100 hours, and the occurrence of white rust on the surface of the plating layer was observed.
상기 표 2에 나타낸 바와 같이, 시편의 냉각속도가 증가함에 따라 백청 발생량이 감소함을 알 수 있었다. 이러한 도금층의 후처리성 향상은 기존 용융아연도금재(표면 Zn 조직 100%)에 최적화된 후처리 용액이 Al 및 Mg가 포함된 금속간화합물과 반응하지 않고 표면을 대부분 덮고 있는 Zn 단상과 반응하여 최적화된 계면을 형성함으로써 기인된 결과라고 판단된다. 한편, 도 4는 본 발명의 실시예에 따라 제조된 용융 아연합금 도금강판의 후처리 후, 염수분무시험을 수행한 후, 그 표면을 관찰한 사진으로, 도 4의 (a) 내지 (d)는 각각 비교예 1, 비교예 4, 발명예 2 및 발명예 3에 따른 용융 아연합금 도금강판의 후처리 후, 염수분무시험을 수행한 후, 그 표면을 관찰한 사진이다.As shown in Table 2, it was found that the amount of white rust was decreased as the cooling rate of the specimen increased. The improvement of the post-treatment of the plating layer is due to the fact that the post-treatment solution optimized for the existing hot-dip galvanizing material (100% of the surface Zn structure) reacts with the Zn single phase which does not react with the intermetallic compound containing Al and Mg, It is judged that the result is the result of forming the optimized interface. 4 (a) to 4 (d) are photographs showing the surface of a hot-dip galvanized steel sheet after a post-treatment of a hot-dip galvanized steel sheet produced according to an embodiment of the present invention, Is a photograph of the surface of a zinc-alloy-plated steel sheet according to Comparative Example 1, Comparative Example 4, Inventive Example 2 and Inventive Example 3, after the post-treatment, after the salt water spray test was conducted.
Claims (6)
상기 소지 강판 상에 형성된 Al-Zn-MgZn2 3원 공정조직을 기지조직으로 하여, 상기 기지조직 내에 Zn-MgZn2 2원 공정조직이 분산되어 있는 하부 금속조직부; 및
상기 하부 금속조직부 상에 형성된, Zn 단상조직을 기지조직으로 하는 상부 금속조직부를 포함하고,
상기 상부 금속조직부 최표면의 Zn 단상조직 면적 점유율이 80% 이상인 내흑변성 및 표면외관이 우수한 용융아연합금 도금강판.
Base steel sheet;
The hold plate formed on the Al-Zn-MgZn 2 3 won by a process known as tissue organization, Zn-MgZn 2 2 won process organization bottom which is dispersed in the base metal jojikbu tissue; And
And an upper metal structure portion formed on the lower metal structure portion and having a Zn single phase structure as a base structure,
The hot-dip galvanized steel sheet according to any one of claims 1 to 3, wherein the hot-rolled steel sheet has a black-topped structure occupying 80% or more of a single-phase single-
상기 용융아연합금 도금강판의 표면조도(Ra)는 0.8㎛ 이하인 내흑변성 및 표면외관이 우수한 용융아연합금 도금강판.
The method according to claim 1,
Wherein the surface roughness (Ra) of the hot-dip galvanized steel sheet is 0.8 占 퐉 or less and the hot weather resistance and surface appearance are excellent.
상기 용융아연합금 도금강판의 광택도는 280 이상인 내흑변성 및 표면외관이 우수한 용융아연합금 도금강판.
The method according to claim 1,
Wherein the hot-dip galvanized steel sheet has a gloss of at least 280 and is excellent in weatherability and surface appearance.
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