KR100342310B1 - Method for manufacturing hot dip galvanized steel sheets with excellent plating adhesion and corrosion resistance - Google Patents
Method for manufacturing hot dip galvanized steel sheets with excellent plating adhesion and corrosion resistance Download PDFInfo
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- KR100342310B1 KR100342310B1 KR1019970062031A KR19970062031A KR100342310B1 KR 100342310 B1 KR100342310 B1 KR 100342310B1 KR 1019970062031 A KR1019970062031 A KR 1019970062031A KR 19970062031 A KR19970062031 A KR 19970062031A KR 100342310 B1 KR100342310 B1 KR 100342310B1
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- rolled steel
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- 238000007747 plating Methods 0.000 title claims abstract description 50
- 238000004519 manufacturing process Methods 0.000 title claims abstract description 27
- 238000000034 method Methods 0.000 title claims abstract description 27
- 230000007797 corrosion Effects 0.000 title claims abstract description 16
- 238000005260 corrosion Methods 0.000 title claims abstract description 16
- 229910001335 Galvanized steel Inorganic materials 0.000 title claims abstract description 12
- 239000008397 galvanized steel Substances 0.000 title claims abstract description 12
- 229910000831 Steel Inorganic materials 0.000 claims abstract description 48
- 239000010959 steel Substances 0.000 claims abstract description 48
- 238000010438 heat treatment Methods 0.000 claims abstract description 41
- HCHKCACWOHOZIP-UHFFFAOYSA-N Zinc Chemical compound [Zn] HCHKCACWOHOZIP-UHFFFAOYSA-N 0.000 claims abstract description 10
- 229910052725 zinc Inorganic materials 0.000 claims abstract description 10
- 239000011701 zinc Substances 0.000 claims abstract description 10
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 claims abstract description 8
- 229910052739 hydrogen Inorganic materials 0.000 claims abstract description 8
- 239000001257 hydrogen Substances 0.000 claims abstract description 8
- 238000005096 rolling process Methods 0.000 claims abstract description 3
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 claims description 33
- 229910052782 aluminium Inorganic materials 0.000 claims description 33
- 230000008569 process Effects 0.000 claims description 19
- 238000005246 galvanizing Methods 0.000 claims description 7
- 238000000151 deposition Methods 0.000 claims 1
- 230000009467 reduction Effects 0.000 abstract description 12
- 230000007613 environmental effect Effects 0.000 abstract description 2
- 238000007598 dipping method Methods 0.000 abstract 1
- 238000005554 pickling Methods 0.000 description 17
- 238000006722 reduction reaction Methods 0.000 description 13
- UQSXHKLRYXJYBZ-UHFFFAOYSA-N Iron oxide Chemical compound [Fe]=O UQSXHKLRYXJYBZ-UHFFFAOYSA-N 0.000 description 5
- 230000000694 effects Effects 0.000 description 5
- KFZAUHNPPZCSCR-UHFFFAOYSA-N iron zinc Chemical compound [Fe].[Zn] KFZAUHNPPZCSCR-UHFFFAOYSA-N 0.000 description 5
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 description 4
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 description 4
- 230000008859 change Effects 0.000 description 4
- 238000007796 conventional method Methods 0.000 description 4
- XEEYBQQBJWHFJM-UHFFFAOYSA-N iron Substances [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 4
- -1 iron-aluminum compound Chemical class 0.000 description 4
- 229910021328 Fe2Al5 Inorganic materials 0.000 description 3
- 230000009471 action Effects 0.000 description 3
- 230000008901 benefit Effects 0.000 description 3
- 230000015572 biosynthetic process Effects 0.000 description 3
- 238000005098 hot rolling Methods 0.000 description 3
- 238000002161 passivation Methods 0.000 description 3
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 2
- FAPWRFPIFSIZLT-UHFFFAOYSA-M Sodium chloride Chemical compound [Na+].[Cl-] FAPWRFPIFSIZLT-UHFFFAOYSA-M 0.000 description 2
- 239000002253 acid Substances 0.000 description 2
- 239000003112 inhibitor Substances 0.000 description 2
- 239000011159 matrix material Substances 0.000 description 2
- 239000000203 mixture Substances 0.000 description 2
- 239000007921 spray Substances 0.000 description 2
- 229910015372 FeAl Inorganic materials 0.000 description 1
- 229910015392 FeAl3 Inorganic materials 0.000 description 1
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 1
- 229910001297 Zn alloy Inorganic materials 0.000 description 1
- 229910045601 alloy Inorganic materials 0.000 description 1
- 239000000956 alloy Substances 0.000 description 1
- KCZFLPPCFOHPNI-UHFFFAOYSA-N alumane;iron Chemical class [AlH3].[Fe] KCZFLPPCFOHPNI-UHFFFAOYSA-N 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 229910052681 coesite Inorganic materials 0.000 description 1
- 230000002301 combined effect Effects 0.000 description 1
- 229910052906 cristobalite Inorganic materials 0.000 description 1
- 230000007423 decrease Effects 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000005238 degreasing Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 238000003912 environmental pollution Methods 0.000 description 1
- 229910052595 hematite Inorganic materials 0.000 description 1
- 239000011019 hematite Substances 0.000 description 1
- 238000007654 immersion Methods 0.000 description 1
- 229910052742 iron Inorganic materials 0.000 description 1
- LIKBJVNGSGBSGK-UHFFFAOYSA-N iron(3+);oxygen(2-) Chemical compound [O-2].[O-2].[O-2].[Fe+3].[Fe+3] LIKBJVNGSGBSGK-UHFFFAOYSA-N 0.000 description 1
- SZVJSHCCFOBDDC-UHFFFAOYSA-N iron(II,III) oxide Inorganic materials O=[Fe]O[Fe]O[Fe]=O SZVJSHCCFOBDDC-UHFFFAOYSA-N 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 230000007246 mechanism Effects 0.000 description 1
- 239000011148 porous material Substances 0.000 description 1
- 230000001681 protective effect Effects 0.000 description 1
- 238000011084 recovery Methods 0.000 description 1
- 150000003839 salts Chemical class 0.000 description 1
- 229910052710 silicon Inorganic materials 0.000 description 1
- 239000010703 silicon Substances 0.000 description 1
- 239000000377 silicon dioxide Substances 0.000 description 1
- 235000012239 silicon dioxide Nutrition 0.000 description 1
- 239000011780 sodium chloride Substances 0.000 description 1
- 238000005507 spraying Methods 0.000 description 1
- 238000009628 steelmaking Methods 0.000 description 1
- 229910052682 stishovite Inorganic materials 0.000 description 1
- 231100000331 toxic Toxicity 0.000 description 1
- 230000002588 toxic effect Effects 0.000 description 1
- 229910052905 tridymite Inorganic materials 0.000 description 1
- 239000002699 waste material Substances 0.000 description 1
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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
- C23C2/00—Hot-dipping or immersion processes for applying the coating material in the molten state without affecting the shape; Apparatus therefor
- C23C2/02—Pretreatment of the material to be coated, e.g. for coating on selected surface areas
- C23C2/022—Pretreatment of the material to be coated, e.g. for coating on selected surface areas by heating
- C23C2/0222—Pretreatment of the material to be coated, e.g. for coating on selected surface areas by heating in a reactive atmosphere, e.g. oxidising or reducing atmosphere
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
- B05D—PROCESSES FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
- B05D3/00—Pretreatment of surfaces to which liquids or other fluent materials are to be applied; After-treatment of applied coatings, e.g. intermediate treating of an applied coating preparatory to subsequent applications of liquids or other fluent materials
- B05D3/002—Pretreatement
-
- 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
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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
- 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
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- 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
Description
본 발명은 내식성 및 도금밀착성이 우수한 탈스케일 공정생략형 용융아연도금강판 제조방법에 관한 것으로서, 보다 상세하게는 제철의 용융아연도금 열연강판 제조공정(Pickling & Galvanizing Line)에 있어서 열연강판의 표면에 형성된 스케일(Scale)층을 산세공정이나 기계적 박리공정에서 제거시키지 않고 용융아연도금 열연강판의 제조공정중의 도금조 이전에 설치되어있는 환원가열대에서 열연판의 스케일층을 환원시킴으로써 열연스케일 제거로 유발되는 환경문제 및 제조원가를 절감시키면서 동시에 도금욕의 알루미늄 농도를 적정하게 유지함으로써 무산세법에 의한 용융아연도금 열연강판 제조를 위한 환원가열대의 열처리조건을 확대시킬 수 있을 뿐 아니라 아연의 희생방식 작용과 알루미늄의 부동태 작용의 복합적인 효과로 내식성 및 도금밀착성이 우수한 탈스케일 공정 생략형 용융아연도금 열연강판의 제조방법에 관한 것이다.The present invention relates to a method for producing a descaled hot dip galvanized steel sheet having excellent corrosion resistance and plating adhesion, and more particularly, to a surface of a hot rolled steel sheet in a hot dip galvanizing line manufacturing process (Pickling & Galvanizing Line) of steel making. The scale layer of the hot-rolled sheet is reduced by reducing the scale layer of the hot-rolled sheet in the heating stage installed before the plating bath in the manufacturing process of the hot-dip galvanized hot-rolled steel sheet without removing the formed scale layer in the pickling process or the mechanical peeling process At the same time, the aluminum concentration of the plating bath is properly maintained while reducing the environmental problems and manufacturing costs, and the heat treatment conditions of the reducing heating plate for hot dip galvanized hot-rolled steel sheet by the pickling method can be expanded, as well as the sacrificial method of zinc and aluminum Corrosion resistance and plating adhesion It relates to a process for producing a superior descaling process abbreviated-dip galvanized hot-rolled steel sheet.
일반적으로 용융아연도금 열연강판의 제조는 열간압연후 생산되는 열연산세강판(Pickled & Oiled Steel) 보다 우수한 내식성을 부여하기 위해서 열연판을 산세한 후 용융아연도금을 실시하여 강판의 부가가치를 증대시킬 목적으로 개발된 기술이다.In general, the manufacture of hot-dip galvanized hot-rolled steel sheet is intended to increase the added value of the steel sheet by pickling the hot-rolled plate and then hot-dip galvanizing to give better corrosion resistance than pickled and oiled steel produced after hot rolling. It was developed as a technology.
상기의 열간압연공정중 조압연 과정이후에 형성되는 스케일을 2차 스케일이라하며 공기와 접촉하는 최외층에 헤마타이트(Hematite), 계속하여 기지조직쪽으로 마그네타이트(Magnetite) 그리고 기지조직과 인접한 뷔스타이트(Wustite)층으로 구성되고 그 두께는 약 10㎛이다.The scale formed after the rough rolling process in the hot rolling process is called a secondary scale, and hematite in the outermost layer in contact with air, continuously magnetite toward the base tissue and the bustite adjacent to the base tissue ( Wustite) layer and its thickness is about 10 mu m.
용융아연도금 열연강판 제조공정에서 이러한 스케일은 도금밀착성을 크게 저해하므로 산세공정에서 염산 혹은 황산용액과부식억제제를 혼합한 산세액으로 제거시킨다.In the hot dip galvanized hot rolled steel sheet manufacturing process, such scale greatly inhibits the adhesion of the plating, and thus, the pickling process removes the hydrochloric acid or sulfuric acid solution and the pickling solution mixed with the corrosion inhibitor.
그러나, 산세공정에서 산세된 열연강판에는 잔존 산화피막이 100∼570Å 정도의 층을 형성시키고 있어 용융아연도금 처리시 도금밀착성을 크게 저하시키는 요인으로 작용한다.However, in the hot-rolled steel sheet pickled in the pickling process, the remaining oxide film forms a layer of about 100 to 570 kPa, which acts as a factor that greatly reduces the plating adhesion during hot dip galvanizing.
그러므로 가열대에서 480∼500℃의 온도에서 7∼15%의 수소농도 분위기에서 아래 반응식(1∼3)과 같은 기구에 의해 잔존산화피막을 완전히 환원시킨후 용융아연욕조에서 도금처리를 행한다.Therefore, in the heating zone, the remaining oxide film is completely reduced by a mechanism such as the following reaction formula (1 to 3) in a hydrogen concentration atmosphere of 7 to 15% at a temperature of 480 to 500 ° C., followed by plating in a molten zinc bath.
3Fe2O3+ H2→ 2Fe3O4+ H2O ………… (1)3Fe 2 O 3 + H 2 → 2Fe 3 O 4 + H 2 O. … … … (One)
Fe3O4+ H2→ 3FeO + H2O ………… (2)Fe 3 O 4 + H 2 → 3 FeO + H 2 O. … … … (2)
FeO + H2→ Fe + H2O ………… (3)FeO + H 2 → Fe + H 2 O... … … … (3)
산세공정에서 스케일층을 산세법에 의해 제거시킬때 형성된 스케일층의 조성에 따라 산세성의 큰 차이가 있으므로 기지조직의 일부는 과산세되어 소지철이 노출되어 강판표면이 거칠고 수소취성, 철손실 및 산손실 등의 문제가 발생될 뿐 아니라 짧은 시간내에 산세가 완료되어야 하기 때문에 가열조건, 산농도관리, 부식억제제 적정농도관리 등 복잡한 조업조건 유지가 상당히 난해한 실정이다.In the pickling process, there is a big difference in pickling properties depending on the composition of the scale layer formed when the scale layer is removed by the pickling method. It is difficult to maintain complex operating conditions such as heating conditions, acid concentration management, and corrosion inhibitor appropriate concentration management because the pickling must be completed within a short time as well as problems such as the above.
또한 독성과 부식성이 강한 염산 또는 황산 등이 산세용액으로 사용되기 때문에 산회수 처리시설 및 폐용액 처리시설 등의 관리 등 제조원가 상승은 물론이고 심각한 환경오염문제를 야기시킬 수 있을 것이다.In addition, since hydrochloric acid or sulfuric acid, which is highly toxic and corrosive, is used as a pickling solution, it may cause a serious environmental pollution problem as well as an increase in manufacturing cost such as management of an acid recovery treatment facility and a waste solution treatment facility.
그리고 강중에 실리콘(Si)이 약 0.2∼0.3% 이상이 되면 도금밀착성은 현저히 저하되는데, 고강도 고가공성의 용도로 사용되는 Si이 0.1wt.% 이상 첨가된 열연강판의 스케일층과 기지조직의 경계에는 페욜라이트(2FeO.SiO2)가 형성되며키잉효과(Keying Effect)에 의해 산세공정에서 완전히 산세되지 않고 잔존되어 미도금부로 될 것이다. 그러므로 산세공정에서도 완전히 제거되지 않는 스케일층이 잔존될 것이며 계속되는 가열대에서의 환원작용에 의해서도 크게 향상되지는 않을 것이다.When the silicon (Si) in the steel is about 0.2 to 0.3% or more, the plating adhesion is significantly lowered.The boundary between the scale layer and the matrix of the hot rolled steel sheet containing 0.1 wt.% Or more of Si, which is used for high strength and high workability. In the peoyrite (2FeO.SiO2) is formed, the keying effect (Keying Effect) will not remain completely pickled in the pickling process will remain unplated. Therefore, the scale layer, which is not completely removed even in the pickling process, will remain and will not be greatly improved by the subsequent reduction in the heating zone.
본 발명은 상기와 같은 문제점을 해결하기 위하여 용융아연 열연강판 제조공정에서 열연강판의 스케일층 제거공정을 생략하고 다음 설비인 환원가열대 공정에서 열연강판의 표면에 형성된 스케일층을 환원시킬 수 있도록 조업조건을 설정함으로써 제조원가 절감을 극대화시킴과 동시에 도금욕의 알루미늄 농도를 적절히 조정함으로써 열연스케일 제거공정 생략형 용융도금 열연강판 제조를 위한 환원가열대의 열처리조건을 확대시킬 수 있을 뿐 아니라 아연의 희생방식 작용과 알루미늄의 부동태 작용의 복합적인 효과로 내식성 및 도금밀착성이 우수한 탈스케일공정 생략형 용융아연도금 열연강판의 제조방법을 제공하는 것을 그 목적으로 한다.The present invention omits the scale layer removal step of the hot rolled steel sheet in the molten zinc hot rolled steel sheet manufacturing process in order to solve the above problems, and operating conditions to reduce the scale layer formed on the surface of the hot rolled steel sheet in the next heating step In addition to maximizing manufacturing cost savings and adjusting the aluminum concentration of the plating bath appropriately, the heat treatment conditions of the reduction heating stage for the hot-rolled hot-rolled hot-rolled steel sheet manufacturing process can be expanded, as well as the sacrificial method effect of zinc. It is an object of the present invention to provide a method for producing a descaling step omitted hot dip galvanized hot rolled steel sheet having excellent corrosion resistance and plating adhesion due to the complex effect of the passivation effect of aluminum.
도 1은 본 발명에 따른 내식성 및 도금밀착성이 우수한 탈스케일 공정생략형 용융아연도금강판 제조방법에 따라 제조된 용융아연도금 열연강판과 종래방법에 따라 제조된 도금강판을 도금욕의 알루미늄 농도 변화에 대한 도금밀착성의 변화를 도시한 그래프도;1 is a hot-dip galvanized hot-rolled steel sheet prepared according to the method of manufacturing a hot-dip galvanized steel sheet having excellent corrosion resistance and plating adhesion according to the present invention and the plated steel sheet prepared according to the conventional method in the aluminum concentration change of the plating bath. A graph showing changes in plating adhesion with respect to;
도 2는 도금욕의 알루미늄 농도가 증가하여 도금밀착성을 향상시킴에 따라 종래법에 비해 본 발명의 환원가열대의 열처리조건의 범위가 확대된 것을 나타내는 그래프도;2 is a graph showing that the range of heat treatment conditions of the reducing heating table of the present invention is expanded as compared with the conventional method as the aluminum concentration of the plating bath is increased to improve plating adhesion.
도 3은 본 발명에 의해 도금욕 중의 알루미늄 농도를 변화시킴에 따라 발생하는 적청발생 면적률의 변화를 나타내는 그래프도이다.Figure 3 is a graph showing the change in the area of red-blue generating area generated by varying the aluminum concentration in the plating bath according to the present invention.
상기와 같은 목적을 달성하기 위하여, 본 발명은 종래 용융아연도금 열연강판을 제조하는 방법에 있어서, 열간압연된 강판의 열연스케일층 제거공정을 생략하여 환원가열대로 상기 열연강판을 투입하는 단계와, 상기 환원가열대로 투입된 열연강판을 환원열처리온도를 550∼820℃, 열처리유지시간을 상기 환원열처리온도에 따라 30∼400초, 수소농도를 10∼30%으로 유지하여 열연강판의 표면스케일층을 환원열처리하는 단계와, 상기 환원열처리된 열연강판을 알루미늄이 0.3∼5.0wt.% 포함하는 용융아연 도금조에 침적하여 용융아연 도금하는 단계와, 상기 용융아연 도금된 강판을 조질압연하는 단계로 구성되는 것을 특징으로 하는 내식성 및 도금밀착성이 우수한 탈스케일공정 생략형 용융아연도금 열연강판 제조방법.을 제공한다.In order to achieve the above object, the present invention is a method of manufacturing a hot-dip galvanized hot-rolled steel sheet, the step of injecting the hot-rolled steel sheet as a reduction heating by eliminating the hot-rolled scale layer removal process of the hot rolled steel sheet, Reducing the surface scale layer of the hot rolled steel sheet by maintaining the reduced heat treatment temperature of the hot rolled steel sheet introduced into the reducing heating zone at 550 to 820 ° C., the heat treatment holding time of 30 to 400 seconds, and the hydrogen concentration of 10 to 30% according to the reducing heat treatment temperature. Heat-treating, immersing the reduced-heat-treated hot-rolled steel sheet in a molten zinc plating bath containing 0.3 to 5.0 wt.% Of aluminum, and hot-rolling the hot-dip galvanized steel sheet. It provides a method of manufacturing a hot-dipped galvanized steel sheet omitted in the descaling process excellent in corrosion resistance and plating adhesion characterized by.
이하, 본 발명의 수치한정 이유에 대하여 설명한다.EMBODIMENT OF THE INVENTION Hereinafter, the reason for numerical limitation of this invention is demonstrated.
환원열처리온도를 550∼820℃로 하는 이유는 550℃이하에서는 도금밀착성을 확보하기 위하여 장시간의 열처리 유지시간이 필요하여 생산성이 저하되고 820℃이상에서는 도금후 도금강판의 인장강도가 기존의 용융도금 열연강판보다 약 10Kg/㎟ 정도 저하되기 때문이다.The reduction heat treatment temperature is 550 ~ 820 ℃, the long time heat treatment holding time is required in order to secure the plating adhesion below 550 ℃, and the productivity is lowered. It is because about 10 Kg / mm <2> falls compared with a hot rolled steel sheet.
또한, 열처리유지시간을 열처리온도에 따라 30∼120초 이상 400초 이하로 유지하는 이유는 30초 이하에서는 환원반응이 발생하지 않아 목적한 도금밀착성을 얻어낼 수 가 없고 400초 이상에서는 강판의 연화현상이 발생하기 때문이다. 그리고 수소농도를 10%이상으로 유지하는 이유는 10%미만에서는 환원반응의 주매체인 수소의 부족으로 환원반응이 원할하게 발생하지 않기 때문이다.The reason why the heat treatment holding time is maintained at 30 to 120 seconds or more and 400 seconds or less depending on the heat treatment temperature is that a reduction reaction does not occur in 30 seconds or less, so that the desired plating adhesion cannot be obtained. This is because the phenomenon occurs. The reason why the hydrogen concentration is maintained at 10% or more is that the reduction reaction does not occur smoothly due to the lack of hydrogen as the main medium of the reduction reaction at less than 10%.
또한, 도금욕 중의 알루미늄 농도를 0.3∼5.0wt.%로 한정하는 이유는 0.3wt.% 미만에서는 알루미늄에 의한 강판상부의 철-아연화합물 형성의 억제력이 부족하여 내식성을 향상시키지 못하고 열처리온도의 범위를 확대시키는 역할을 하지지 못하며, 5.0wt.%을 초과하면 용융아연도금 열연강판 제조에 대한 경제적인 이점이 없어진다.In addition, the reason for limiting the aluminum concentration in the plating bath to 0.3 to 5.0 wt.% Is that less than 0.3 wt.% Is insufficient to suppress the formation of iron-zinc compound on the upper surface of the steel sheet by aluminum, which does not improve the corrosion resistance and the range of heat treatment temperature. It does not play a role of enlarging, and if it exceeds 5.0wt.%, There is no economic advantage for manufacturing hot-dip galvanized steel sheet.
이하, 첨부된 도면을 참조하여 본 발명을 보다 상세하게 설명한다.Hereinafter, with reference to the accompanying drawings will be described in detail the present invention.
도 1은 도금욕의 알루미늄 농도 변화에 본 발명의 용융아연도금 열연강판의도금밀착성의 변화를 종래방법과 비교한 그래프 도이고, 도 2는 도금욕의 알루미늄 농도가 증가하여 도금밀착성을 향상시킴에 따라 종래법에 비해 본 발명의 환원가열대의 열처리조건의 범위가 확대된 것을 나타내는 그래프 도이고, 도 3은 본 발명에 의해 도금욕중의 알루미늄 농도를 변화시킴에 따라 발생하는 적청발생 면적률의 변화를 나타내는 그래프 도이다.1 is a graph showing the change in plating adhesion of the hot-dip galvanized hot-rolled steel sheet of the present invention to the aluminum concentration of the plating bath compared with the conventional method, Figure 2 is to increase the aluminum adhesion of the plating bath to improve the plating adhesion Accordingly, it is a graph showing the range of heat treatment conditions of the reducing heating table of the present invention compared to the conventional method, Figure 3 is a change in the area of red-blue generated by changing the aluminum concentration in the plating bath according to the present invention It is a graph which shows.
먼저 도 1에 도시된 바와 같이 종래 0.2 wt.%의 알루미늄 농도에서는 550℃ 및 650℃, 10% 수소분위기의 환원가열조건에서 120초 유지할 경우 도금밀착성은 양호하지 못했으나 환원가열온도에 따라 알루미늄의 농도가 증가함에 따라 도금밀착성은 양호하게 되었다. 즉, 550℃에서 120초 환원열처리한 강판은 3wt.% 알루미늄 농도이상의 도금욕에서 그리고 650℃에서 120초 환원열처리한 강판은 0.5wt.% 알루미늄 이상의 도금욕에서 용융아연도금을 실시하면 같은 정도의 도금밀착성이 우수한 탈스케일공정 생략형 용융아연도금 열연강판을 제조하는 것이 가능하게 되었다.First, as shown in FIG. 1, when the aluminum concentration of 0.2 wt.% Is maintained for 120 seconds at 550 ° C, 650 ° C, and 10% hydrogen atmosphere under reduced heating conditions, plating adhesion is not good, As the concentration increased, the plating adhesion became good. That is, the steel sheet subjected to reduction heat treatment at 550 ° C. for 120 seconds was subjected to hot dip galvanization in a plating bath having a concentration of 3 wt.% Aluminum or higher and the steel sheet subjected to reduction heat treatment at 120 seconds at 650 ° C. in a plating bath of 0.5 wt.% Aluminum. It has become possible to manufacture a descaling step omitted hot dip galvanized hot rolled steel sheet having excellent plating adhesion.
그러므로 기존의 알루미늄 농도인 0.25wt.%보다 높은 0.3wt.% 이상의 알루미늄 농도에서는 도금밀착성 및 환원가열처리조건의 범위를 확대시킬 수 있게 되고 알루미늄 농도가 5.0wt.%이상일 때는 용융아연도금 열연강판 제조에 대한 경제적인 이점이 없게 된다.Therefore, it is possible to extend the range of plating adhesion and reducing heat treatment conditions at the aluminum concentration of 0.3wt.% Or more higher than the existing aluminum concentration of 0.25wt.%, And when the aluminum concentration is 5.0wt.% Or more, it is necessary to manufacture hot-dip galvanized steel sheet. There is no economic advantage for this.
또한 도 2에 도시된 바와 같이 550℃에서는 120초, 820℃에서는 30초 이상의 환원열처리 후에는 알루미늄 농도에 따라 도금밀착성이 우수한 탈스케일공정 생략형 용융아연도금 열연강판을 제조하는 것이 가능하다.In addition, as shown in FIG. 2, after the reduction heat treatment of 120 seconds at 550 ° C. and 30 seconds or more at 820 ° C., it is possible to manufacture a hot-dip galvanized hot-rolled steel sheet having a descaling process with excellent plating adhesion depending on aluminum concentration.
여기서, 도금욕중에 첨가되는 알루미늄의 작용에 대하여 설명한다.Here, the action of aluminum added in the plating bath will be described.
알루미늄은 도금광택을 향상시키고 아연도금욕내의 산화물 환원 및 도금층 계면에서 형성되는 취약한 철-아연화합물 형성을 억제함으로써 도금밀착성을 향상시키며 부동태 역할에 의한 내식성을 향상시키는 잇점이 있다.Aluminum has the advantage of improving plating adhesion and corrosion resistance by the passivation role by improving plating glossiness and suppressing oxide reduction in the galvanizing bath and formation of a weak iron-zinc compound formed at the interface of the plating layer.
따라서 통상적인 용융아연 도금욕에는 알루미늄을 0.12∼0.25wt.% 첨가하여 도금재와 도금층 계면에 형성되는 철-아연 화합물층의 두께를 줄이고 있다.Therefore, the thickness of the iron-zinc compound layer formed at the interface between the plating material and the plated layer is reduced by adding 0.12 to 0.25 wt.% Of aluminum to the conventional hot dip galvanizing bath.
이는 알루미늄이 아연보다 철과의 친화력이 훨씬 크므로 강판 표면에 얇은 합금층 피막을 급속히 형성시키기 때문이며, 침지시간이 길어지거나 욕온도가 높아지면 피막이 깨지고 철-아연 합금층이 성장한다. 그 피막의 조성은 철-알루미늄 화합물(Fe2Al5) 또는 철-아연-알루미늄 조합이고, 0.1∼4.0 wt.% 알루미늄 농도에서는 철-알루미늄 화합물(Fe2Al5)이 단시간내에 형성된다.This is because aluminum has a much higher affinity with iron than zinc, so that a thin alloy layer film is rapidly formed on the surface of the steel sheet. If the immersion time is long or the bath temperature is high, the film is broken and the iron-zinc alloy layer grows. The composition of the film is an iron-aluminum compound (Fe2Al5) or an iron-zinc-aluminum combination, and at a concentration of 0.1 to 4.0 wt.% Aluminum, the iron-aluminum compound (Fe2Al5) is formed in a short time.
그리고, 4∼5 wt.% 알루미늄 농도에서는 더 두꺼운 철-알루미늄 화합물(FeAl3)을 초기에 형성한다. 이 때 철-알루미늄화합물(FeAl3)층은 깨지기 쉬우나, 하부에 Fe2Al5 가 존재하여 보호역할을 해준다.At a concentration of 4 to 5 wt.% Aluminum, thicker iron-aluminum compounds (FeAl 3) are initially formed. At this time, the iron-aluminum compound (FeAl3) layer is fragile, but Fe2Al5 is present in the lower part to act as a protective role.
이렇게 알루미늄 첨가는 탈스케일공정 생략형 용융아연 열연강판 제조공정에서 환원열처리로 형성된 스케일층의 기공 및 스케일층과 기지조직의 경계층에 확산되어 취성이 높은 철-아연 화합물의 형성을 억제하는 작용을 한다.In this way, aluminum addition acts to suppress the formation of highly brittle iron-zinc compound by diffusing to pores of scale layer formed by reduction heat treatment and boundary layer of scale layer and matrix structure in the process of manufacturing de-scaled hot dip galvanized steel sheet. .
이하, 실시예와 함께 본 발명을 설명한다.Hereinafter, the present invention will be described with examples.
〈실시예〉<Example>
본 발명에 의한 용융아연도금 열연강판을 제조하기 위하여 용융도금 시뮬레이터를 이용하여 100㎜ × 200㎜ ×1.2㎜ 두께의 열연판을 탈지한 후 가열대의 열처리온도는 550∼820℃, 열처리 유지시간은 30∼400초로 유지시키고 수소농도를 10∼30%로 변화시키면서 환원열처리한 후 도금욕의 알루미늄 성분을 0.2∼5.0wt.%로 변화시킨 용융아연 도금욕에서 도금한후 도금강판의 내식성을 평가하기 위해서 염수분무시험기(Salt Spray Tester)를 이용하여 35℃의 5% 염화나트륨 수용액을 1.0 Kg/㎠의 분무압으로 1㎖/hr의 양을 분무하여 46시간 후에 표면을 관찰하였다.In order to manufacture the hot-dip galvanized hot-rolled steel sheet according to the present invention, after degreasing the hot-rolled sheet having a thickness of 100 mm × 200 mm × 1.2 mm using a hot dip plating simulator, the heat treatment temperature of the heating table is 550 to 820 ° C., and the heat treatment holding time is 30. In order to evaluate the corrosion resistance of the coated steel sheet after plating in a molten zinc plating bath in which the aluminum component of the plating bath was changed to 0.2 to 5.0 wt. The surface was observed after 46 hours by spraying an amount of 1 ml / hr with a spray pressure of 1.0 Kg /
그 결과 도 3에 나타낸 것과 같이 10% 수소분위기의 550∼820℃의 환원가열온도에서 30∼400초 열처리한 후 0.2 wt.% 알루미늄 농도의 기존 도금욕에서 도금하였을 때는 46시간 후 100% 적청이 발생하였으나 알루미늄 농도가 증가할수록 적청 발생면적률이 현저히 감소함을 알 수 있다.As a result, as shown in FIG. 3, when heat-treated at 30 to 400 seconds at a reducing heating temperature of 550 to 820 ° C. in a 10% hydrogen atmosphere, 100% red blue was obtained after 46 hours when plated in a conventional plating bath having 0.2 wt.% Aluminum concentration. However, as the aluminum concentration increases, the area of red blue generation decreases significantly.
상기와 같은 본 발명에 의하여 기존방법에서 열연강판의 스케일층 제거를 위한 산세공정이나 기계적 박리공정을 생략할 수 있으며 산세공정에서 제거되기 어려운 페욜라이트 등의 스케일 결함을 환원가열대에서 환원시켜 기존의 산세공정이나 쇼트브라스트 공정 등을 생략시킴으로써 기존의 용융도금 열연강판의 제조원가를 크게 저감시킴과 동시에 알루미늄 농도를 적정하게 유지함으로써 무산세법에 의한 용융도금 열연강판 제조를 위한 환원가열대의 열처리조건을 확대시킬 수 있고 아연의 희생방식 작용과 알루미늄의 부동태 작용의 복합적인 효과로 내식성 및 도금밀착성이 우수한 탈스케일 생략형 용융아연도금 열연강판을 제조할 수 있다.According to the present invention as described above, the pickling process or mechanical peeling process for removing the scale layer of the hot rolled steel sheet can be omitted in the existing method, and the existing pickling by reducing scale defects such as peyolite, which is difficult to remove in the pickling process, in a reduction heating zone. By eliminating the process and the shot blast process, the manufacturing cost of the hot-dip hot-rolled steel sheet can be greatly reduced, and the aluminum concentration can be maintained appropriately. It is possible to manufacture a descaled omitted hot dip galvanized hot rolled steel sheet having excellent corrosion resistance and plating adhesion due to the combined effect of the sacrificial anticorrosive action of zinc and the passivation action of aluminum.
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| KR100905667B1 (en) | 2002-12-27 | 2009-06-30 | 주식회사 포스코 | Method for manufacturing cold rolled steel sheet without pickling process |
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| KR19990057390A (en) * | 1997-12-29 | 1999-07-15 | 이구택 | Process for producing acid-free alloyed hot-dip galvanized hot rolled steel sheet with excellent powder resistance and surface quality |
| KR100368728B1 (en) * | 1998-12-29 | 2003-03-31 | 주식회사 포스코 | Manufacturing method of hot-dip galvanized steel sheet containing silicon |
| TW418122B (en) | 1998-12-29 | 2001-01-11 | Po Hang Iron & Steel | Method for manufacturing hot rolled galvanized steel sheet at high speed, with pickling skipped |
| KR100368551B1 (en) * | 1998-12-29 | 2003-03-28 | 주식회사 포스코 | Manufacturing method of high speed hot dip galvanized hot rolled steel sheet |
| KR20010058264A (en) * | 1999-12-27 | 2001-07-05 | 이구택 | A Method for Manufacturing Hot Rolled Steel Sheet Having Excellent Lubrication Property |
| KR100905653B1 (en) * | 2002-12-27 | 2009-06-30 | 주식회사 포스코 | Preparing method of non-pickling galvanized hot-rolled steel sheet with excellent coating adhesion |
| KR101669718B1 (en) | 2014-07-01 | 2016-10-27 | 김동회 | Incubator with multi-directional angle structure |
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| KR100905667B1 (en) | 2002-12-27 | 2009-06-30 | 주식회사 포스코 | Method for manufacturing cold rolled steel sheet without pickling process |
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