KR20240095945A - Cold rolled steel sheet having Zirconium oxide film - Google Patents
Cold rolled steel sheet having Zirconium oxide film Download PDFInfo
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- 239000010960 cold rolled steel Substances 0.000 title claims abstract description 32
- RVTZCBVAJQQJTK-UHFFFAOYSA-N oxygen(2-);zirconium(4+) Chemical compound [O-2].[O-2].[Zr+4] RVTZCBVAJQQJTK-UHFFFAOYSA-N 0.000 title description 9
- 229910001928 zirconium oxide Inorganic materials 0.000 title description 9
- 229910052726 zirconium Inorganic materials 0.000 claims abstract description 43
- QCWXUUIWCKQGHC-UHFFFAOYSA-N Zirconium Chemical compound [Zr] QCWXUUIWCKQGHC-UHFFFAOYSA-N 0.000 claims abstract description 42
- 230000003746 surface roughness Effects 0.000 claims abstract description 15
- 229910052710 silicon Inorganic materials 0.000 claims abstract description 7
- 229910052717 sulfur Inorganic materials 0.000 claims abstract description 6
- 229910052804 chromium Inorganic materials 0.000 claims abstract description 5
- 239000012535 impurity Substances 0.000 claims abstract description 5
- 229910052748 manganese Inorganic materials 0.000 claims abstract description 5
- 239000010408 film Substances 0.000 description 37
- 229910000831 Steel Inorganic materials 0.000 description 19
- 239000010959 steel Substances 0.000 description 19
- 229910019142 PO4 Inorganic materials 0.000 description 18
- NBIIXXVUZAFLBC-UHFFFAOYSA-K phosphate Chemical compound [O-]P([O-])([O-])=O NBIIXXVUZAFLBC-UHFFFAOYSA-K 0.000 description 18
- 239000010452 phosphate Substances 0.000 description 18
- 230000000052 comparative effect Effects 0.000 description 17
- 239000000463 material Substances 0.000 description 13
- 239000003973 paint Substances 0.000 description 12
- 239000000203 mixture Substances 0.000 description 9
- 238000005260 corrosion Methods 0.000 description 8
- 230000007797 corrosion Effects 0.000 description 8
- 238000010586 diagram Methods 0.000 description 8
- 239000000956 alloy Substances 0.000 description 7
- 229910045601 alloy Inorganic materials 0.000 description 7
- 230000000694 effects Effects 0.000 description 6
- 238000000034 method Methods 0.000 description 6
- 239000011248 coating agent Substances 0.000 description 5
- 238000000576 coating method Methods 0.000 description 5
- 238000005755 formation reaction Methods 0.000 description 5
- 230000015572 biosynthetic process Effects 0.000 description 4
- 238000005238 degreasing Methods 0.000 description 4
- 238000002203 pretreatment Methods 0.000 description 4
- 230000008569 process Effects 0.000 description 4
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 3
- 229910004298 SiO 2 Inorganic materials 0.000 description 3
- 230000008901 benefit Effects 0.000 description 3
- 229910052799 carbon Inorganic materials 0.000 description 3
- 238000007598 dipping method Methods 0.000 description 3
- 230000007613 environmental effect Effects 0.000 description 3
- 238000005530 etching Methods 0.000 description 3
- JEIPFZHSYJVQDO-UHFFFAOYSA-N iron(III) oxide Inorganic materials O=[Fe]O[Fe]=O JEIPFZHSYJVQDO-UHFFFAOYSA-N 0.000 description 3
- 238000004519 manufacturing process Methods 0.000 description 3
- 230000003449 preventive effect Effects 0.000 description 3
- 230000009257 reactivity Effects 0.000 description 3
- 238000005406 washing Methods 0.000 description 3
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 3
- FAPWRFPIFSIZLT-UHFFFAOYSA-M Sodium chloride Chemical compound [Na+].[Cl-] FAPWRFPIFSIZLT-UHFFFAOYSA-M 0.000 description 2
- 230000008859 change Effects 0.000 description 2
- 238000006243 chemical reaction Methods 0.000 description 2
- 230000007423 decrease Effects 0.000 description 2
- 238000004070 electrodeposition Methods 0.000 description 2
- 238000005516 engineering process Methods 0.000 description 2
- 238000012851 eutrophication Methods 0.000 description 2
- 238000002474 experimental method Methods 0.000 description 2
- 229910001385 heavy metal Inorganic materials 0.000 description 2
- 238000001000 micrograph Methods 0.000 description 2
- 238000010422 painting Methods 0.000 description 2
- 230000002829 reductive effect Effects 0.000 description 2
- 239000010802 sludge Substances 0.000 description 2
- 239000007921 spray Substances 0.000 description 2
- DXIGZHYPWYIZLM-UHFFFAOYSA-J tetrafluorozirconium;dihydrofluoride Chemical compound F.F.F[Zr](F)(F)F DXIGZHYPWYIZLM-UHFFFAOYSA-J 0.000 description 2
- ZPZDIFSPRVHGIF-UHFFFAOYSA-N 3-aminopropylsilicon Chemical compound NCCC[Si] ZPZDIFSPRVHGIF-UHFFFAOYSA-N 0.000 description 1
- LLQHSBBZNDXTIV-UHFFFAOYSA-N 6-[5-[[4-[2-(2,3-dihydro-1H-inden-2-ylamino)pyrimidin-5-yl]piperazin-1-yl]methyl]-4,5-dihydro-1,2-oxazol-3-yl]-3H-1,3-benzoxazol-2-one Chemical compound C1C(CC2=CC=CC=C12)NC1=NC=C(C=N1)N1CCN(CC1)CC1CC(=NO1)C1=CC2=C(NC(O2)=O)C=C1 LLQHSBBZNDXTIV-UHFFFAOYSA-N 0.000 description 1
- AFCARXCZXQIEQB-UHFFFAOYSA-N N-[3-oxo-3-(2,4,6,7-tetrahydrotriazolo[4,5-c]pyridin-5-yl)propyl]-2-[[3-(trifluoromethoxy)phenyl]methylamino]pyrimidine-5-carboxamide Chemical compound O=C(CCNC(=O)C=1C=NC(=NC=1)NCC1=CC(=CC=C1)OC(F)(F)F)N1CC2=C(CC1)NN=N2 AFCARXCZXQIEQB-UHFFFAOYSA-N 0.000 description 1
- 229910003134 ZrOx Inorganic materials 0.000 description 1
- JAWMENYCRQKKJY-UHFFFAOYSA-N [3-(2,4,6,7-tetrahydrotriazolo[4,5-c]pyridin-5-ylmethyl)-1-oxa-2,8-diazaspiro[4.5]dec-2-en-8-yl]-[2-[[3-(trifluoromethoxy)phenyl]methylamino]pyrimidin-5-yl]methanone Chemical compound N1N=NC=2CN(CCC=21)CC1=NOC2(C1)CCN(CC2)C(=O)C=1C=NC(=NC=1)NCC1=CC(=CC=C1)OC(F)(F)F JAWMENYCRQKKJY-UHFFFAOYSA-N 0.000 description 1
- 239000002253 acid Substances 0.000 description 1
- 230000002411 adverse Effects 0.000 description 1
- 230000033228 biological regulation Effects 0.000 description 1
- 238000006482 condensation reaction Methods 0.000 description 1
- 239000000470 constituent Substances 0.000 description 1
- 229910052802 copper Inorganic materials 0.000 description 1
- 239000013078 crystal Substances 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 238000001035 drying Methods 0.000 description 1
- 230000007062 hydrolysis Effects 0.000 description 1
- 238000006460 hydrolysis reaction Methods 0.000 description 1
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- 230000001788 irregular Effects 0.000 description 1
- 230000000670 limiting effect Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 229910052759 nickel Inorganic materials 0.000 description 1
- 229910052760 oxygen Inorganic materials 0.000 description 1
- 230000000704 physical effect Effects 0.000 description 1
- 238000003825 pressing Methods 0.000 description 1
- 230000009467 reduction Effects 0.000 description 1
- 238000011160 research Methods 0.000 description 1
- 238000012827 research and development Methods 0.000 description 1
- 238000005096 rolling process Methods 0.000 description 1
- 150000003839 salts Chemical class 0.000 description 1
- 229920006395 saturated elastomer Polymers 0.000 description 1
- 239000011780 sodium chloride Substances 0.000 description 1
- 238000007711 solidification Methods 0.000 description 1
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- 238000005507 spraying Methods 0.000 description 1
- 230000009897 systematic effect Effects 0.000 description 1
- 238000012360 testing method Methods 0.000 description 1
- 239000010409 thin film Substances 0.000 description 1
Images
Classifications
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- 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
- C23C22/00—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals
- C23C22/05—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions
- C23C22/06—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions using aqueous acidic solutions with pH less than 6
- C23C22/34—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions using aqueous acidic solutions with pH less than 6 containing fluorides or complex fluorides
-
- 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
- C21D8/0221—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the working steps
- C21D8/0236—Cold rolling
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C16/00—Alloys based on zirconium
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/38—Ferrous alloys, e.g. steel alloys containing chromium with more than 1.5% by weight of manganese
Abstract
지르코늄피막 형성된 냉연강판이 제공된다.
본 발명은, 중량%로, C: 0.160% 이하, Si: 0.03~0.5%, Mn: 0.14~2.6%, P: 0.015% 이하, S: 0.012% 이하, Cr:0.01~0.5%, 잔여 Fe 및 불가피한 불순물을 포함하고, Mn/Si＞3을 만족하며, 그 표면 조도 Ra가 1.1~1.4를 만족하는 냉연강판으로서, 상기 냉연강판의 표면에 지르코늄이 40mg/m2 이상의 부착량으로 형성되어 있는 냉연강판에 관한 것이다. A cold rolled steel sheet formed with a zirconium film is provided.
The present invention, in weight percent, C: 0.160% or less, Si: 0.03 to 0.5%, Mn: 0.14 to 2.6%, P: 0.015% or less, S: 0.012% or less, Cr: 0.01 to 0.5%, residual Fe and A cold-rolled steel sheet that contains inevitable impurities, satisfies Mn/Si>3, and has a surface roughness Ra of 1.1 to 1.4, in which zirconium is formed on the surface of the cold-rolled steel sheet in an adhesion amount of 40 mg/m 2 or more. It's about.
Description
본 발명은 냉연강판의 전처리피막으로서 지르코늄피막이 형성된 냉연강판에관한 것으로, 보다 상세하게는, 강판의 조성 성분 및 표면 조도 등을 최적화하여 우수한 밀착성을 가질 뿐만 아니라 도장내식성이 우수한 지르코늄피막 형성된 냉연강판에 관한 것이다. The present invention relates to a cold-rolled steel sheet on which a zirconium film is formed as a pretreatment film of a cold-rolled steel sheet. More specifically, it relates to a cold-rolled steel sheet on which a zirconium film is formed, which not only has excellent adhesion but also has excellent painting corrosion resistance by optimizing the composition and surface roughness of the steel sheet. It's about.
자동차에 사용되는 철강 소재(냉연재, 도금재 등)와 도장과의 밀착력을 매우 향상시키기 위해 과거부터 인산염이 사용되어 인산염피막을 전처리피막으로 형성하여 왔다. 인산염은 반응성이 좋고 안정적이며 원가가 싸 거의 모든 자동차사가 도장 전 전처리공정으로 인산염을 사용하였다. 실제 자동차라인에서는 수만리터의 인산염 bath에 자동차를 디핑(dipping)만 함으로써 간단하게 철강 소재 표면에 인산염피막을 부착시켜왔다. 그러나 글로벌 환경규제 및 탄소중립이 정책화되면서, 중금속이면서 바다/강에 부영양화 문제를 일으킬수 있는 P를 대체하는 노력이 일어나고 있다.In order to greatly improve the adhesion between steel materials (cold rolled materials, plated materials, etc.) used in automobiles and paint, phosphate has been used in the past to form a phosphate film as a pretreatment film. Phosphate is highly reactive, stable, and inexpensive, so almost all automobile companies used phosphate as a pretreatment process before painting. In actual automobile lines, a phosphate film has been attached to the surface of steel materials simply by dipping the car in tens of thousands of liters of phosphate bath. However, as global environmental regulations and carbon neutrality become policies, efforts are being made to replace P, which is a heavy metal and can cause eutrophication problems in oceans and rivers.
종래 인산염 피막을 형성하는 기술의 대체로서, 전처리피막으로서 지르코늄피막을 사용하는 기술이 개발되고 있다. 아시아 및 유럽계 자동차사에서는 이미 자동차 생산에 필요한 전처리용액으로 사용을 하고 있으며, 국내에도 1~3년 내에 도입이 이루어질 전망이다. 리터당 수 g 단위로 사용되는 인산염에 비해 ppm 단위로 사용되는 지르코늄은 중금속 노출 및 부영양화, 반응 sludge 측면에서 큰 장점을 가지고 있다.As an alternative to the conventional technology for forming a phosphate film, a technology using a zirconium film as a pretreatment film is being developed. Asian and European automobile companies are already using it as a pretreatment solution for automobile production, and it is expected to be introduced in Korea within 1 to 3 years. Compared to phosphate, which is used in units of several grams per liter, zirconium, which is used in units of ppm, has great advantages in terms of heavy metal exposure, eutrophication, and reaction sludge.
하지만 지르코늄은 환경적인 장점을 가지고 있으나, 인산염의 두께와 부착량(2~4㎛, 2~5g/m2)에 비해 지르코늄은 매우 얇은 두께와 부착량(20~50nm, 20~100mg/m2)으로 인해 자동차 도장의 품질(내식성, 치핑성 등)에 영향을 미치는 제반 조건들에 대한 연구가 미진하며, 이에 대한 데이터도 많지 않은 실정이다. 따라서 우수한 도장밀착성 뿐만 아니라 도장내식성을 가지는 지르코늄피막의 형성방법에 대한 체계적인 연구개발 요구가 지속되어 오고 있다. However, zirconium has environmental advantages, but compared to the thickness and adhesion amount of phosphate (2~4㎛, 2~5g/ m2 ), zirconium has a very thin thickness and adhesion amount (20~50nm, 20~100mg/ m2 ). As a result, research on various conditions that affect the quality of automobile paint (corrosion resistance, chipping resistance, etc.) is insufficient, and there is not much data on this. Therefore, there has been a continued demand for systematic research and development on methods for forming zirconium films that have not only excellent paint adhesion but also paint corrosion resistance.
본 발명은 냉연강판의 전처리피막으로서 도장밀착성 뿐만아니라 도장내식성이 우수한 지르코늄피막이 형성된 냉연강판을 제공함을 목적으로 한다. The purpose of the present invention is to provide a cold-rolled steel sheet formed with a zirconium film that is excellent in paint adhesion as well as paint corrosion resistance as a pre-treatment film for cold-rolled steel sheets.
본 발명의 과제는 상술한 내용에 한정되지 아니한다. 본 발명이 속하는 기술분야에서 통상의 지식을 가지는 자라면 본 발명 명세서의 전반적인 사항으로부터 본 발명의 추가적인 과제를 이해하는데 아무런 어려움이 없을 것이다. The object of the present invention is not limited to the above-described content. Anyone skilled in the art to which the present invention pertains will have no difficulty in understanding the additional problems of the present invention from the overall details of the present invention specification.
본 발명의 일 측면은, One aspect of the present invention is,
중량%로, C: 0.160% 이하, Si: 0.03~0.5%, Mn: 0.14~2.6%, P: 0.015% 이하, S: 0.012% 이하, Cr:0.01~0.5%, 잔여 Fe 및 불가피한 불순물을 포함하고, Mn/Si＞3을 만족하며, 그 표면 조도 Ra가 1.1~1.4를 만족하는 냉연강판으로서, 상기 냉연강판의 표면에 지르코늄이 40mg/m2 이상의 부착량으로 형성되어 있는 냉연강판에 관한 것이다. In weight percent, C: 0.160% or less, Si: 0.03 to 0.5%, Mn: 0.14 to 2.6%, P: 0.015% or less, S: 0.012% or less, Cr: 0.01 to 0.5%, including residual Fe and unavoidable impurities. It relates to a cold-rolled steel sheet that satisfies Mn/Si>3 and has a surface roughness Ra of 1.1 to 1.4, in which zirconium is formed on the surface of the cold-rolled steel sheet in an adhesion amount of 40 mg/m 2 or more.
상기 Cr 함량이 0.01~0.03% 인 것이 바람직하다.It is preferable that the Cr content is 0.01 to 0.03%.
상기 냉연강판에 부착되는 지르코늄의 부착량이 40~55mg/m2인 것이 바람직하다. It is preferable that the amount of zirconium attached to the cold rolled steel sheet is 40 to 55 mg/m 2 .
상술한 구성의 본 발명에 따르면, 냉연강판의 전처리피막으로서 도장밀착성 뿐만아니라 도장내식성이 우수한 지르코늄피막이 형성된 냉연강판을 효과적으로 제공할 수 있다. According to the present invention having the above-described structure, it is possible to effectively provide a cold-rolled steel sheet formed with a zirconium film that has excellent paint adhesion as well as paint corrosion resistance as a pre-treatment film for the cold-rolled steel sheet.
따라서 종래 전처리피막으로 이용되고 있는 인산염피막을 대체할 수 있으므로 종래 P의 이용에 따른 제반 환경문제를 해소할 수 있는 장점이 있다. Therefore, since it can replace the phosphate film used as a conventional pretreatment film, it has the advantage of solving all environmental problems caused by the conventional use of P.
도 1은 강판의 전처리 피막의 단면결정을 보이는 주사현미경사진으로서, (a)는 인산염피막을, 그리고 (b) 지르코늄피막에 대한 사진을 나타낸다.
도 2는 강판의 전처리피막으로서 지르코늄피막의 코팅단면을 FIB-EDS로 성분별 측정한 결과를 나타내는 그림이다.
도 3은 본 발명에서 실시예에서 성분원소의 함량이 Zr 부착량에 영향을 주는 것을 보여주는 그림으로서, (a)는 C, (b)는 Si, 그리고 (c)는 Cr의 영향을 보여주는 그림이다.
도 4은 본 발명의 실시예에서 강판의 합금조성에 따른 지르코늄 부착량의 변화와 SST blister와의 상관관계를 나타내는 그림이다. Figure 1 is a scanning micrograph showing a cross-section of a pre-treatment film of a steel plate, (a) showing a phosphate film, and (b) a zirconium film.
Figure 2 is a diagram showing the results of measuring the coating cross-section of a zirconium film as a pretreatment film for a steel plate by component using FIB-EDS.
Figure 3 is a diagram showing that the content of the component elements affects the amount of Zr adhesion in the examples of the present invention, where (a) is a diagram showing the influence of C, (b) is Si, and (c) is a diagram showing the influence of Cr.
Figure 4 is a diagram showing the correlation between the change in zirconium adhesion amount and SST blister according to the alloy composition of the steel sheet in an embodiment of the present invention.
이하, 본 발명을 설명한다.Hereinafter, the present invention will be described.
도 1은 강판의 전처리 피막의 단면결정을 보이는 주사현미경사진으로서, (a)는 인산염피막을, 그리고 (b) 지르코늄피막에 대한 사진을 나타낸다. Figure 1 is a scanning micrograph showing a cross-section of a pre-treatment film of a steel plate, (a) showing a phosphate film, and (b) a zirconium film.
도 1(a)에 나타난 바와 같이, 종래 표면조정 공정을 거친 전처리를 통하여 인산염 seed가 생성이 되고 인산염 공정에서 결정이 성장하여 지름이 3~10㎛의 구형 인산염이 형성됨을 알 수 있다. 이에 반하여, 도 1(b)와 같이, 지르코늄은 비정형 형태로 SEM으로 관찰이 되지 않으며, 두께도 매우 얇은 15~50nm 수준이어서 FIB 등과 같은 최정밀 측정장비로만 관찰이 가능하다. As shown in Figure 1(a), it can be seen that a phosphate seed is created through pretreatment using a conventional surface adjustment process, and crystals grow in the phosphate process to form a spherical phosphate with a diameter of 3 to 10㎛. On the other hand, as shown in Figure 1(b), zirconium is in an irregular form and cannot be observed by SEM, and its thickness is very thin, at the level of 15 to 50 nm, so it can only be observed with the most precise measuring equipment such as FIB.
도 2는 강판의 전처리피막으로서 지르코늄피막의 코팅단면을 FIB-EDS로 성분별 측정한 결과를 나타내는 그림이다. 도 2에 나타난 바와 같이, ZrOx로 박막을 형성하여 Zr과 O가 균일하게 박막이 형성된 것이 확인되나, 전착도장 품질을 향상시키기 위해 초기 용액에 적용이 되었던 Cu와 Ni은 포함이 되지 않음을 알 수 있다. Figure 2 is a diagram showing the results of measuring the coating cross-section of a zirconium film as a pretreatment film for a steel plate by component using FIB-EDS. As shown in Figure 2, it was confirmed that Zr and O were uniformly formed by forming a thin film with ZrOx, but Cu and Ni, which were applied to the initial solution to improve the electrodeposition coating quality, were not included. there is.
본 발명은 전처리피막으로서 상술한 종래 인산염피막 대신에 지르코늄 산화물피막을 냉연강판 표면에 형성함을 특징으로 하며, 이때, 도장밀착성 및 도장내식성의 관점에서 Zr 부착량을 결정하고, 이러한 Zr 부착량이 안정적으로 형성할 수 있도록 냉연강판 조성성분 및 표면조도를 최적화함을 특징으로 한다. The present invention is characterized in that a zirconium oxide film is formed on the surface of a cold rolled steel sheet instead of the conventional phosphate film described above as a pretreatment film. At this time, the amount of Zr adhesion is determined from the viewpoint of paint adhesion and paint corrosion resistance, and this amount of Zr adhesion is stably maintained. It is characterized by optimizing the composition and surface roughness of cold rolled steel sheets so that they can be formed.
이러한 본 발명은, 중량%로, C: 0.160% 이하, Si: 0.03~0.5%, Mn: 0.14~2.6%, P: 0.015% 이하, S: 0.012% 이하, Cr:0.01~0.5%, 잔여 Fe 및 불가피한 불순물을 포함하고, Mn/Si＞3을 만족하며, 그 표면 조도 Ra가 1.1~1.4를 만족하는 냉연강판으로서, 상기 냉연강판의 표면에 지르코늄이 40mg/m2 이상의 부착량으로 형성되어 있는 냉연강판을 제공한다. In this invention, in weight percent, C: 0.160% or less, Si: 0.03 to 0.5%, Mn: 0.14 to 2.6%, P: 0.015% or less, S: 0.012% or less, Cr: 0.01 to 0.5%, residual Fe and unavoidable impurities, satisfies Mn/Si > 3, and has a surface roughness Ra of 1.1 to 1.4, wherein zirconium is formed on the surface of the cold rolled steel sheet in an adhesion amount of 40 mg/m 2 or more. Provides steel plates.
본 발명에서는 상기 냉연강판에 함유되는 주요 산화물 생성 원소들이 Cr, Si, Mn 등으로서, SiO2는 표면에 생성시 다소 지르코늄 생성을 방해하나 Zr 부착량에 가장 영향성이 큰 원소는 Cr이다. 상기 Cr은 0.5% 이상 함유될 경우 Zr 부착량이 상당히 저감되는 것으로 확인되었으며, 이는 Cr이 강판 표면에 존재할 경우, noble화 되어 free-F의 에칭력이 상당히 떨어지는 것으로 보인다. 이에 반하여, C은 표면 에칭력을 떨어뜨려 인산염이나 지르코늄 피막 현상을 방해할 수 있어 지르코늄 부착량에 거의 영향을 미치지 않는다.In the present invention, the main oxide forming elements contained in the cold rolled steel sheet are Cr, Si, Mn, etc. SiO 2 somewhat hinders the formation of zirconium when formed on the surface, but Cr is the element that has the greatest influence on the amount of Zr adhesion. It was confirmed that when the Cr content is more than 0.5%, the amount of Zr adhesion is significantly reduced. This means that when Cr is present on the surface of the steel sheet, it becomes noble and the etching power of free-F appears to be significantly reduced. In contrast, C reduces the surface etching power and can interfere with the phosphate or zirconium film development, so it has little effect on the amount of zirconium adhesion.
이하, 본 발명의 냉연강판의 합금 조성성분 및 그 함량 제한사유를 간략히 설명하며, 여기에서 달리 규정한 바가 없다면 함량의 단위는 중량%를 나타낸다. Hereinafter, the alloy composition of the cold-rolled steel sheet of the present invention and the reasons for limiting its content will be briefly described. Unless otherwise specified, the unit of content indicates weight%.
C: 0.160% 이하C: 0.160% or less
탄소는 그 함량이 성분이 늘어남에 따라 표면이 noble해지고 반응성이 떨어진다. 탄소의 성분이 0.16%를 초과하면 급격히 반응성이 나빠져 인산염 및 Zr 형성에 방해가 될 수 있다. As the carbon content increases, the surface becomes noble and the reactivity decreases. If the carbon content exceeds 0.16%, reactivity may rapidly deteriorate, interfering with the formation of phosphate and Zr.
Si: 0.03~0.5%Si: 0.03~0.5%
Si은 전혀 없을 경우 소재의 물성을 맞추기 어려우며 많이 존재할 경우 표면에 SiO2 산화물을 형성시켜 Zr형성 반응을 억제시킬 수 있다. If there is no Si at all, it is difficult to match the physical properties of the material, and if there is a lot of Si, it can suppress the Zr formation reaction by forming SiO 2 oxide on the surface.
Mn: 0.14~2.6%Mn: 0.14~2.6%
Mn은 자체로도 산화물 형성을 하지만 무엇보다도 Si산화물을 억제시킨다. SiO2는 표면 에칭이 어려우나, MnSiO2는 에칭에 약해 상대적으로 용해가 쉽게 되며 Zr형성에 도움이 된다. 또한 Mn 함량이 0.14% 이상으로 함유되어야 소재 물성을 가질 수 있다. 그러나 그 함량이 2.6%를 초과하면 산화물을 형성하여 피막형성에 좋은 효과를 주지는 못한다. Mn itself forms oxides, but above all, it inhibits Si oxides. SiO 2 is difficult to etch the surface, but MnSiO 2 is weak to etching, so it is relatively easy to dissolve and helps form Zr. In addition, the Mn content must be greater than 0.14% to have material properties. However, if the content exceeds 2.6%, oxides are formed and do not have a good effect on film formation.
P: 0.015% 이하, S: 0.012% 이하P: 0.015% or less, S: 0.012% or less
기타 원소들에 비해서 큰 영향을 주지는 않으나, P, S가 많게되면 sludge가 많이 발생하게 되어, 바람직하지 않다. Although it does not have a significant effect compared to other elements, if P and S are present in large quantities, a lot of sludge occurs, which is not desirable.
Cr: 0.01~0.5%Cr: 0.01~0.5%
Cr은 산화막 형성이나 소재 표면을 noble화 시키는데 핵심적인 원소이기 때문에 적은 양에도 가장 악영향을 미친다. 고강도강에서는 소재의 물성효과를 위해 완전 0%로 할 수 없고 적어도 0.01% 이상 포함되어야 하나, 그 함량이 0.5%를 초과하면 Zr 반응을 방해하여 70~80% 이상 Zr 부착량이 줄어들게 될 수 있다. Since Cr is a key element in forming an oxide film or making the surface of a material noble, it has the most adverse effect even in small amounts. In high-strength steel, it cannot be completely 0% for the effect of the material's properties and must be included at least 0.01%. However, if the content exceeds 0.5%, it may interfere with the Zr reaction and reduce the amount of Zr adhesion by more than 70-80%.
Mn/Si＞3 Mn/Si＞3
Mn은 Si과 소재 내부에서 반응하여 내부산화물을 생성한다. 이때, Mn이 Si보다 3배 이상 많은 양이 존재하면, Si이 내부에서 반응하여 표면 산화물 생성이 어려워질 수 있다. Mn reacts with Si inside the material to generate internal oxides. At this time, if Mn is present in an amount three times greater than Si, Si may react internally, making it difficult to generate surface oxide.
본 발명은 상기 성분 이외에도 잔부 Fe 및 기타 불가피한 불순물로 이루어지질 수 있다.In addition to the above components, the present invention may be comprised of the balance Fe and other unavoidable impurities.
또한 본 발명은 적정수준의 지르코늄 부착량을 확보하기 위해, 상기 냉연강판의 표면조도 Ra를 1.1~1.4 범위로 제어하는 것이 바람직하다. 이 범위에서 Zr 부착량이 가장 많이 잘 형성된다. In addition, in the present invention, in order to secure an appropriate level of zirconium adhesion, it is preferable to control the surface roughness Ra of the cold rolled steel sheet in the range of 1.1 to 1.4. In this range, the largest amount of Zr adhesion is formed.
만일 상기 표면조도가 1.1 미만이면, 이는 SPM을 너무 낮은 압하력으로 눌러주기 때문에 조도가 너무 낮게 나오는데, 이럴 경우 전 공정에서 발생한 표면 미세흠을 효과적으로 제거하지 못하게 되고, 이에 따라 많은 미세흠 존재로 인하여 잔류방청유가 많이 존재하여 지르코늄의 반응성이 나빠져 지르코늄 부착량이 낮게 나올 수 있다. If the surface roughness is less than 1.1, the roughness is too low because the SPM is pressed with too low a pressing force. In this case, surface microflaws generated in the previous process cannot be effectively removed, resulting in the presence of many microflaws. If there is a lot of residual rust preventive oil, the reactivity of zirconium may deteriorate and the amount of zirconium attached may be low.
반면 상기 표면조도가 1.4를 초과하면, 이는 미세흠을 줄이는데는 효과가 있으나, 너무 깊게 골(짜기)이 생겨, 방청유의 고상화(고체화)를 유발할 수 있다. 또한 탈지용액, 수세한 용액들이 잔류하여 패인 골 부분에 지르코늄 생성이 어려울 수 있어 바람직하지 않다. On the other hand, if the surface roughness exceeds 1.4, it is effective in reducing micro-flaws, but too deep valleys may occur, which may cause solidification of the rust preventive oil. In addition, it is undesirable because it may be difficult to create zirconium in the pitted areas where the degreasing solution and the washing solution remain.
상술한 바와 같은 합금조성과 표면조도를 갖는 본 발명의 냉연강판 표면에는 지르코늄이 40mg/m2 이상의 부착량으로 형성되어 있는 것이 바람직하다. 만일 상기 부착량이 40mg/m2 미만이면 지르코늄 산화층피막의 두께가 얇아 소망하는 도장밀착성 및 도장내식성을 확보할수 없다. It is preferable that zirconium is formed in an adhesion amount of 40 mg/m 2 or more on the surface of the cold rolled steel sheet of the present invention having the alloy composition and surface roughness described above. If the adhesion amount is less than 40 mg/m 2 , the thickness of the zirconium oxide layer is too thin to ensure desired paint adhesion and paint corrosion resistance.
바람직하게는 상기 지르코늄 부착량을 40~55mg/m2 범위로 제어하는 것이다. 너무 두꺼운 지르코늄 산화층 피막은 그 형성에 많은 비용과 시간이 들어 비경제적일뿐만 아니라, 형성 효과도 포화되기 때문이다. Preferably, the zirconium adhesion amount is controlled in the range of 40 to 55 mg/m 2 . This is because a zirconium oxide layer that is too thick is not only uneconomical because it requires a lot of cost and time to form, but also the formation effect is saturated.
한편 본 발명에서는 이러한 지르코늄 산화층피막을 형성하는 구체적인 제조방법에 제한되는 것이 아니라, 알려진 다양한 방법을 제한없이 이용할 수 있다. 즉, 통상의 탈지, 수세, 지르코늄처리, 수세 및 건조공정을 거쳐 냉연강판상에 지르코늄 산화층피막을 형성할 수 있다. 그리고 상기 지르코늄 처리는 상기 수세된 냉연강판을 소정 농도를 갖는 헥사플로오지르코닉산 용액에 디핑함으로써 수행될수 있으며, 이러한 디핑처리에 의해 가수분해와 축합반응을 통하여 지르코늄 산화물 피막을 형성할 수 있다. Meanwhile, the present invention is not limited to a specific manufacturing method for forming such a zirconium oxide layer film, and various known methods can be used without limitation. That is, a zirconium oxide layer film can be formed on a cold rolled steel sheet through the usual degreasing, water washing, zirconium treatment, water washing, and drying processes. The zirconium treatment can be performed by dipping the washed cold-rolled steel sheet in a hexafluorozirconic acid solution having a predetermined concentration. Through this dipping treatment, a zirconium oxide film can be formed through hydrolysis and condensation reactions.
이하 본 발명의 바람직한 실시예를 통하여 본 발명을 상세히 설명한다. 그러나 하기 실시예는 본 발명의 바람직한 일 실시예일뿐 본 발명이 하기 실시예에 한정되는 것은 아니다.Hereinafter, the present invention will be described in detail through preferred embodiments of the present invention. However, the following example is only a preferred example of the present invention and the present invention is not limited to the following example.
(실시예 1)(Example 1)
하기 표 1과 같은 합금 조성을 가진 냉연강판들을 마련하였으며, 이들의 표면조도는 일률적으로 Ra 1.1~1.4 범위를 만족하도록 SPM 압연을 거쳤다. 이후, 이들 강판들을 35℃ 90초 동안 탈지용액에 디핑한 후, 30~45초 동안 스프레이로 수세하였다. 이어, 상기 강판들을 헥사플로오지르코닉산 용액에 디핑하여 Zr 전처리피막을 형성하였다. 여기에서 상기 핵사플로오지르코니산 용액은, Zr 농도가 200~300ppm, Aminopropylsilane 농도는 100~200ppm, F 농도는 10~80ppm, NO3 농도는 2000~4000, pH 3-4인 용액을 이용하였다. 그리고 상기 전처리된 냉연강판들을 수세후, 80℃에서 10분 동안 오븐에서 건조하여 그 표면에 지르코늄 산화층피막이 형성된 냉연강판을 제조하였다. Cold-rolled steel sheets with the alloy composition shown in Table 1 below were prepared, and their surface roughness was subjected to SPM rolling to uniformly satisfy the range of Ra 1.1 to 1.4. Afterwards, these steel plates were dipped in a degreasing solution at 35°C for 90 seconds and then washed with spray for 30 to 45 seconds. Next, the steel sheets were dipped in a hexafluorozirconic acid solution to form a Zr pretreatment film. Here, the hexafluorozirconi acid solution had a Zr concentration of 200 to 300 ppm, an aminopropylsilane concentration of 100 to 200 ppm, an F concentration of 10 to 80 ppm, a NO3 concentration of 2000 to 4000, and a pH of 3-4. Then, the pretreated cold-rolled steel sheets were washed with water and then dried in an oven at 80°C for 10 minutes to produce a cold-rolled steel sheet with a zirconium oxide layer formed on its surface.
(mg/m2)Zr adhesion amount
(mg/m 2 )
도 3은 상기 표 1의 강판의 성분원소의 함량이 Zr 부착량에 영향을 주는 것을 보여주는 그림으로서, (a)는 C, (b)는 Si, 그리고 (c)는 Cr의 영향을 보여주는 그림이다. 도 3에 나타난 바와 같이, 성분 원소 중 Cr 함량이 지르코늄 부착량이 큰 영향을 줌을 알수 있으며 Cr 함량이 0.5%를 초과하면 실제상 40mg/m2 이상의 지르코늄 부착량을 얻을 수 없음을 알 수 있다. Figure 3 is a diagram showing that the content of the constituent elements of the steel sheet in Table 1 affects the amount of Zr adhesion, with (a) showing the influence of C, (b) showing the influence of Si, and (c) showing the influence of Cr. As shown in Figure 3, it can be seen that the Cr content among the component elements has a great influence on the zirconium adhesion amount, and if the Cr content exceeds 0.5%, it is impossible to actually obtain a zirconium adhesion amount of 40 mg/m 2 or more.
도 4은 본 발명의 실시예에서 강판의 합금조성에 따른 지르코늄 부착량의 변화와 SST blister와의 상관관계를 나타내는 그림이다. Figure 4 is a diagram showing the correlation between the change in zirconium adhesion amount and SST blister according to the alloy composition of the steel sheet in an embodiment of the present invention.
즉, 도 4는 도 3과 같은 지르코늄 부착량을 가졌을 때의 블리스터 크기를 측정한 결과를 나타난 것이다. 본 실험은 지르코늄 처리한 소재에 전착도장(16~18㎛) 처리를 한 후, 칼로 도장 표면을 X표시(직선길이 10cm) 하여 시편을 준비하였다. SST(Salt Spray Test)는 5% NaCl을 1.5~2㎖/hour 염수분무를 480시간 하는 것이다. That is, Figure 4 shows the results of measuring the blister size when the zirconium adhesion amount was the same as in Figure 3. In this experiment, a specimen was prepared by applying electrodeposition coating (16-18㎛) to a zirconium-treated material and then marking the painted surface with an X (straight line length 10cm) with a knife. SST (Salt Spray Test) involves spraying 5% NaCl at a rate of 1.5 to 2 mL/hour for 480 hours.
도 4에 나타난 바와 같이, 지르코늄 부착량이 늘수록 도막의 블리스터가 줄어들어 내식성이 향상되는 것을 볼 수 있다. 특히, 부착량이 40mg/m2이 넘어야 대부분의 자동차사에서 요구하는 냉연재의 블리스터 기준인 4.5nm를 만족할 수 있어 소재의 부착량이 40mg/m2 이상이 되어야 함을 알 수 있다. 그러므로 가능하면 소재의 생산조건을 최적화하여 부착량을 40mg/m2 이상으로 상향시키는 것이 중요하다. As shown in Figure 4, it can be seen that as the amount of zirconium attached increases, blisters in the coating film decrease and corrosion resistance improves. In particular, the adhesion amount must be over 40 mg/m 2 to satisfy the blister standard of 4.5 nm for cold rolled materials required by most automobile companies, so it can be seen that the adhesion amount of the material must be over 40 mg/m 2 . Therefore, if possible, it is important to optimize the production conditions of the material and increase the adhesion amount to 40 mg/m 2 or more.
(실시예 2)(Example 2)
실시예 1의 No. 7 강판을 준비하였다. 다만 본 실험에서는 SPM 단계에서 압하율을 다르게 설정하여, 표면조도가 1.1 미만인 강판, 1.1~1.4를 만족하는 강판, 그리고 1.4를 초과하는 3개의 강판을 마련하였다. 이와 같이, 마련된 강판들을 실시예1과 같은 조건으로 각 냉연강판 표면에 지르코늄 산화층 피막을 형성한 후, 그 표면에 형성된 Zr 부착량을 측정하여, 그 결과를 하기 표 2에 나타내었다. No. 1 of Example 1. 7 A steel plate was prepared. However, in this experiment, the reduction ratio was set differently at the SPM stage, and three steel plates with a surface roughness of less than 1.1, a steel plate satisfying 1.1 to 1.4, and a surface roughness exceeding 1.4 were prepared. After forming a zirconium oxide layer on the surface of each cold rolled steel sheet prepared in this way under the same conditions as in Example 1, the amount of Zr adhesion formed on the surface was measured, and the results are shown in Table 2 below.
상기 표 2에 나타난 바와 같이, 강판 합금조성이 본 발명범위 내라도 표면 조도 Ra가 1.1~1.4를 만족하지 않은 비교예 6-16은 소망하는 지르코늄 부착량을 얻을 수 없음을 알 수 있다. As shown in Table 2, it can be seen that even if the steel sheet alloy composition is within the range of the present invention, the desired zirconium adhesion amount cannot be obtained in Comparative Examples 6-16 in which the surface roughness Ra does not satisfy 1.1 to 1.4.
이상에서 설명한 바와 같이, 본 발명의 상세한 설명에서는 본 발명의 바람직한 실시 예에 관하여 설명하였으나, 본 발명이 속하는 기술분야에서 통상의 지식을 가진 자라면 본 발명의 범주에서 벗어나지 않는 한도 내에서 여러 가지 변형이 가능함은 물론이다. 따라서 본 발명의 권리 범위는 설명된 실시 예에 국한되어 정해져서는 안 되며, 후술하는 청구범위뿐만 아니라, 이와 균등한 것들에 의해 정해져야 한다.As described above, the detailed description of the present invention has described preferred embodiments of the present invention, but those skilled in the art can make various modifications without departing from the scope of the present invention. Of course this is possible. Therefore, the scope of rights of the present invention should not be limited to the described embodiments, but should be determined not only by the claims described later, but also by their equivalents.
Claims (3)
In weight percent, C: 0.160% or less, Si: 0.03 to 0.5%, Mn: 0.14 to 2.6%, P: 0.015% or less, S: 0.012% or less, Cr: 0.01 to 0.5%, including residual Fe and unavoidable impurities. A cold-rolled steel sheet that satisfies Mn/Si>3 and has a surface roughness Ra of 1.1 to 1.4, wherein zirconium is formed on the surface of the cold-rolled steel sheet in an adhesion amount of 40 mg/m 2 or more.
The cold rolled steel sheet according to claim 1, wherein the Cr content is 0.01 to 0.03%.
The cold rolled steel sheet according to claim 1, wherein the amount of zirconium attached to the cold rolled steel sheet is 40 to 55 mg/m 2 .
Publications (1)
| Publication Number | Publication Date |
|---|---|
| KR20240095945A true KR20240095945A (en) | 2024-06-26 |
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