KR20020030936A - Cooling method of melting-zinc coated steel having easy moldability - Google Patents
Cooling method of melting-zinc coated steel having easy moldability Download PDFInfo
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- KR20020030936A KR20020030936A KR1020000061303A KR20000061303A KR20020030936A KR 20020030936 A KR20020030936 A KR 20020030936A KR 1020000061303 A KR1020000061303 A KR 1020000061303A KR 20000061303 A KR20000061303 A KR 20000061303A KR 20020030936 A KR20020030936 A KR 20020030936A
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- steel sheet
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- rolled steel
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- 238000001816 cooling Methods 0.000 title claims abstract description 79
- 229910000831 Steel Inorganic materials 0.000 title abstract description 46
- 239000010959 steel Substances 0.000 title abstract description 46
- 239000011701 zinc Substances 0.000 title description 15
- 229910052725 zinc Inorganic materials 0.000 title description 14
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 45
- 238000005275 alloying Methods 0.000 claims abstract description 35
- 239000010960 cold rolled steel Substances 0.000 claims abstract description 27
- 238000010438 heat treatment Methods 0.000 claims abstract description 19
- 239000000498 cooling water Substances 0.000 claims abstract description 13
- 238000005246 galvanizing Methods 0.000 claims abstract description 6
- 229910001335 Galvanized steel Inorganic materials 0.000 claims description 16
- 239000008397 galvanized steel Substances 0.000 claims description 16
- 238000010791 quenching Methods 0.000 abstract description 10
- 238000000034 method Methods 0.000 abstract description 7
- 230000000171 quenching effect Effects 0.000 abstract description 7
- 238000000227 grinding Methods 0.000 abstract description 5
- 238000007747 plating Methods 0.000 description 25
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 18
- HCHKCACWOHOZIP-UHFFFAOYSA-N Zinc Chemical compound [Zn] HCHKCACWOHOZIP-UHFFFAOYSA-N 0.000 description 13
- 229910052742 iron Inorganic materials 0.000 description 9
- 239000000843 powder Substances 0.000 description 7
- 229910045601 alloy Inorganic materials 0.000 description 4
- 239000000956 alloy Substances 0.000 description 4
- 230000000694 effects Effects 0.000 description 4
- 238000004519 manufacturing process Methods 0.000 description 4
- 239000002245 particle Substances 0.000 description 4
- 239000011248 coating agent Substances 0.000 description 3
- 238000000576 coating method Methods 0.000 description 3
- 239000002826 coolant Substances 0.000 description 3
- 239000007788 liquid Substances 0.000 description 3
- 239000000463 material Substances 0.000 description 3
- 238000012545 processing Methods 0.000 description 3
- 230000007797 corrosion Effects 0.000 description 2
- 238000005260 corrosion Methods 0.000 description 2
- 238000009792 diffusion process Methods 0.000 description 2
- 238000005096 rolling process Methods 0.000 description 2
- 238000005507 spraying Methods 0.000 description 2
- 238000012360 testing method Methods 0.000 description 2
- 229910000851 Alloy steel Inorganic materials 0.000 description 1
- 229910001339 C alloy Inorganic materials 0.000 description 1
- 229910001021 Ferroalloy Inorganic materials 0.000 description 1
- 230000002411 adverse Effects 0.000 description 1
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 1
- 229910052782 aluminium Inorganic materials 0.000 description 1
- 238000005452 bending Methods 0.000 description 1
- 238000007664 blowing Methods 0.000 description 1
- 239000004566 building material Substances 0.000 description 1
- 230000000052 comparative effect Effects 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000000151 deposition Methods 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 238000001035 drying Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 229910000765 intermetallic Inorganic materials 0.000 description 1
- 238000004781 supercooling Methods 0.000 description 1
- 238000012546 transfer Methods 0.000 description 1
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
- 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
- C23C2/28—Thermal after-treatment, e.g. treatment in oil bath
- C23C2/29—Cooling or quenching
-
- 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
- B05D3/007—After-treatment
-
- 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
- C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
- C21D1/62—Quenching devices
- C21D1/63—Quenching devices for bath quenching
-
- 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
-
- 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
- C23C2/50—Controlling or regulating the coating processes
Abstract
Description
본 발명은 자동차용 강판 등에 사용되는 합금화 용융아연 도금강판의 냉각방법에 관한 것으로, 보다 상세하게는 용융아연 도금조에서 연속적으로 합금화 열처리된 도금강판을 열처리후 워터퀘칭(WATER QUENCHING)하여 냉각함으로써 내파우더링성 및 우수한 표면품질을 갖도록 한 성형성이 우수한 합금화 용융아연 도금강판의 냉각방법에 관한 것이다.The present invention relates to a method for cooling an alloyed hot-dip galvanized steel sheet used in automotive steel sheets, and more particularly, by cooling and cooling water-quenched (WATER QUENCHING) after heat-treating a plated steel sheet continuously alloyed and heat-treated in a hot-dip zinc bath. The present invention relates to a cooling method of an alloyed hot dip galvanized steel sheet having excellent moldability to have powdering property and excellent surface quality.
합금화 용융아연 도금강판은 도장성, 도장후 내식성이 우수하여 최근 건자재용, 가전용 및 자동차용 강판으로 그 수요가 급증하고 있다.Alloyed hot-dip galvanized steel sheet is excellent in paintability and corrosion resistance after coating, and the demand for this is rapidly increasing as steel sheets for building materials, home appliances and automobiles.
일반적으로, 합금화 용융아연 도금강판의 제조방법은 연속 용융아연 도금공정에서 도금된 강판을 합금화 열처리하여 제조되는 바, 소지강판이 1차로 아연도금된 상태에서 연속적으로 약 470~560℃의 온도범위로 가열하면 소지철의 철성분과 도금층의 아연성분이 상호 확산되어 ζ상, δ1상, Γ상 등의 Fe-Zn계 금속간 화합물이 성장하여 합금화 용융아연 도금층이 형성된다.In general, a method for producing an alloyed hot-dip galvanized steel sheet is produced by alloying heat treatment of the plated steel plate in a continuous hot dip galvanizing process, the base steel sheet is first galvanized in a continuous temperature range of about 470 ~ 560 ℃ When heated, the iron component of the base iron and the zinc component of the plating layer are diffused to each other to grow Fe-Zn-based intermetallic compounds such as ζ phase, δ1 phase, and Γ phase to form an alloyed hot dip galvanized layer.
합금화 용융아연 도금강판의 품질특성은 스폿용접성, 도장후 내식성 및 도장밀착성이 우수하지만 합금화 처리시 과합금화된 강판은 가공시 도금층이 분말형태로 떨어지는 파우더링 현상이 발생되는 문제점이 있다.The quality characteristics of the alloyed hot-dip galvanized steel sheet is excellent in spot weldability, corrosion resistance and coating adhesion after coating, but there is a problem that powdered phenomenon that the plating layer falls into powder form during processing of alloyed steel sheet.
파우더링은 합금철의 철 농도에 따라 비례하여 열화되나 밀착성 및 용접성은 반대로 향상된다. 따라서, 이러한 제특성을 고려할 때 합금화 용융아연 도금강판의 도금층의 최적 철 농도는 도 1에서와 같이, 약 8~12%로 비교적 좁게 되며, 주상(MAIN PHASE)으로 δ1상을 갖도록 하는 것이 보통이다. 이를 위해, 합금화 용융아연 도금강판의 제조시 합금화 열처리후의 냉각 제어기술이 매우 중요하다.Powdering deteriorates in proportion to the iron concentration of ferroalloy, but improves adhesion and weldability. Therefore, in consideration of these characteristics, the optimum iron concentration of the plated layer of the alloyed hot-dip galvanized steel sheet is relatively narrow to about 8 to 12%, as shown in Figure 1, it is common to have a δ 1 phase as the main phase (MAIN PHASE) . For this purpose, the cooling control technology after the alloying heat treatment is very important in the production of alloyed hot-dip galvanized steel sheet.
즉, 합금화 열처리후 도금강판은 최대한 냉각되지 않으면 도금층 내의 아연입자의 밀착성이 완전하지 못하여 상부롤 표면에 떨어져 고착되며, 강판의 표면에압착마크를 유발시키거나 소재 잠열의 영향으로 합금화가 계속 진행하여 과합금화로 발전되어 가공성에 취약한 조직인 Γ조직이 생성되고, 이로인해 가공시 도금층이 분말형태로 떨어져 나가는 파우더링 현상이 발생되기 때문에 최대한 급냉각제어가 요구된다.That is, after the alloying heat treatment, if the plated steel sheet is not cooled as much as possible, the adhesion of the zinc particles in the plated layer may be incomplete, and the surface of the upper roll may be stuck to the surface of the upper roll. Due to the development of overalloy, Γ structure, which is weak to processability, is generated, and thus, quenching control is required as much as possible due to powdering phenomenon in which the plating layer falls off in powder form during processing.
종래에는 냉연강판을 연속적으로 도금조에 통과시켜 합금화 처리한 후 적정 합금화도를 확보한 후 공기냉각대를 통해 냉각함으로써 합금화 용융아연 도금강판을 제조하였다. 그러나, 이러한 공기냉각 방식은 송풍시 공기압에 의해 강판의 진동이 발생되어 강판의 전,후면간에 합금화 열처리온도에 편차가 생기거나 합금화 편차가 심하여 강판의 한쪽면은 과합금화가 그리고 대향면은 미합금화가 발생되며, 공랭효과의 미흡으로 인해 상부롤에서의 강판 온도가 400℃정도 까지 상승되는 단점이 있다.In the related art, a cold rolled steel sheet was continuously passed through a plating bath, followed by alloying to obtain an appropriate degree of alloying, and then cooled through an air cooling zone to manufacture an alloyed hot dip galvanized steel sheet. However, in this air cooling method, the vibration of the steel sheet is generated by the air pressure during blowing, so that the alloying heat treatment temperature varies between the front and rear surfaces of the steel sheet, or the alloying variation is severe, so that one side of the steel sheet is overalloyed and the opposite surface is unalloyed. Is generated, the steel sheet temperature in the upper roll due to the lack of air cooling effect has a disadvantage that the temperature rises to about 400 ℃.
이와 같은 경우 대체로 1.0mm이하 두께의 박물재이거나 또는 도금 부착량이 편면기준으로 약 45~60g/㎡ 정도의 박도금 냉연강판이 그 대상이었으며, 적정 철 농도 범위를 유지하여 과합금화를 방지하면서 보다 후물재에 적용된 예로써 물과 공기를 혼합한 포그 냉각방식에 의해 합금화 용융아연 도금강판을 제조하는 방법이 대한민국 특허 제88580호에 제시된 바 있다.In this case, it was usually a thin material of 1.0 mm or less, or a thin plated cold rolled steel sheet with a plating adhesion amount of about 45 to 60 g / m2 on one side, and prevented over alloying by maintaining an appropriate iron concentration range. As an example applied to a water material, a method of manufacturing an alloyed hot dip galvanized steel sheet by a fog cooling method in which water and air are mixed has been presented in Korean Patent No. 88580.
상기 공개된 방법은 도 2의 도시와 같이, 0.08~0.16wt%의 알루미늄을 함유한 도금조(1)에서 후물재(2.0~4.0mm) 열간압연강판(S)을 용융도금후 도금조(1)의 직상부에 설치된 에어나이프(2)를 통해 도금량을 조절하고, 이후 연속적으로 합금화열처리로(3)에서 열간압연강판의 온도가 480~550℃가 되도록 가열하고, 공기냉각대(4)에서 상기 온도범위로 일정시간 유지한 다음, 공기와 물을 병행하여 고압분사하는 냉각방식에 의해 20~40℃/초 범위의 냉각속도로 급냉하여 상부롤(6)에서 강판온도가 300℃ 이하가 되도록 합금화 열처리하는 방법이다.The disclosed method is as shown in Figure 2, after plating the hot material (2.0 ~ 4.0mm) hot rolled steel sheet (S) in the plating bath (1) containing 0.08 ~ 0.16wt% aluminum plating bath (1) The amount of plating is controlled through the air knife 2 installed on the upper part of the), and subsequently heated in the alloy heat treatment furnace 3 so that the temperature of the hot rolled steel sheet becomes 480 to 550 ° C., and in the air cooling stand 4 After maintaining a certain time in the temperature range, by the cooling method of high-pressure spraying in parallel with air and water to quench at a cooling rate of 20 ~ 40 ℃ / sec so that the steel sheet temperature in the upper roll (6) to 300 ℃ or less Alloying heat treatment.
그러나, 이러한 냉각방식은 공기냉각 방식인 10~25℃/초 보다는 냉각속도가 다소 향상되지만 물입자가 강판 하부로 낙하하므로써 냉각효과가 떨어지거나 심할 경우 합금화로 내부로 낙수하는 현상으로 인해 합금화로 운전조건의 가열평형이 깨져 품질에 악영향을 끼치게 된다. 또한, 포그 냉각의 경우 강판의 온도가 300~400℃ 사이에서는 강판 근접 부위에서 증기막이 형성되어 물입자가 강판에 진입하는 것을 방해하는 현상이 발생하기 때문에 냉각효과가 실제로는 불충분하여 만일 합금화열처리로에서부터 상부롤(5)까지 거리가 가깝거나 강판의 통판속도가 고속인 경우 상부롤(5)에서의 강판온도가 300~350℃ 정도로써 냉각이 불충분하여 도금층 내 과합금화 또는 합금화 편차가 발생하게 된다.However, the cooling method is slightly improved than the air cooling method of 10 ~ 25 ℃ / second, but the cooling effect is reduced due to the water particles fall to the lower part of the steel sheet or if the alloying operation due to the phenomenon of falling into the alloying interior. The heating equilibrium of conditions is broken and adversely affects the quality. In addition, in the case of fog cooling, when the temperature of the steel sheet is between 300 and 400 ° C., a vapor film is formed in the vicinity of the steel sheet, which hinders water particles from entering the steel sheet. When the distance from the upper roll 5 to the upper roll 5 is high or the sheet speed of the steel sheet is high, the steel sheet temperature of the upper roll 5 is about 300 to 350 ° C., and cooling is insufficient, resulting in over alloying or alloying deviation in the plating layer. .
본 발명은 상술한 종래 기술이 갖는 제반 문제점을 감안하여 이를 해결하고자 창안한 것으로, 용융아연이 도금된 냉연강판을 상부롤까지 진행시키고 난 후 연속적으로 하강시키면서 도중에 합금화 열처리후 워터탱크를 통과시켜 강판을 급냉시킴으로써 냉각효율을 높여 합금화 용융아연 도금강판 도금층의 과합금화를 막고 내파우더링성 뿐만 아니라 합금화 균일정도 및 가공특성을 극대화시킬 수 있도록 한 성형성이 우수한 합금화 용융아연 도금강판의 냉각방법을 제공함에 그 목적이 있다.The present invention was devised to solve the above problems in view of the above-described prior art, and after passing the molten zinc plated cold rolled steel sheet to the upper roll and continuously lowering it, the alloy steel plate was passed through the water tank on the way. It provides a cooling method of alloyed hot-dip galvanized steel sheet with excellent moldability to prevent the over alloying of the alloyed hot-dip galvanized steel plate plating layer by maximizing the cooling efficiency and to maximize the alloying uniformity and processing characteristics as well as powder resistance. The purpose is.
본 발명의 상기한 목적은 냉연소지강판을 용융아연 도금조에 통과시켜 도금하고, 도금된 냉연강판을 470~560℃의 온도범위로 가열하여 합금화 열처리한 후 냉각하되; 상기 냉연강판을 80℃이하로 유지되는 워터탱크 내의 냉각수에 침적시켜 냉연강판의 온도가 150℃ 이하가 되도록 냉각속도 100~250℃/초 범위로 수냉각시켜 이루어짐에 의해 달성된다.The above object of the present invention is plated by passing the cold-rolled steel sheet through a hot dip galvanizing bath, and the plated cold-rolled steel sheet is heated to a temperature range of 470 ~ 560 ℃ to cool after alloying heat treatment; The cold rolled steel sheet is achieved by immersing the cooling water in a water tank maintained at 80 ° C. or lower to cool the steel sheet in a cooling rate of 100 to 250 ° C./sec so that the temperature of the cold rolled steel sheet is 150 ° C. or lower.
도 1은 철함량에 따른 품질특성을 보인 관계도,1 is a relationship showing the quality characteristics according to the iron content,
도 2는 종래 기술에 따른 합금화 아연도금강판 제조장치의 일예를 개략적으로 도시한 예시도,Figure 2 is an exemplary view schematically showing an example of an apparatus for producing alloyed galvanized steel sheet according to the prior art,
도 3은 본 발명에 따른 합금화 용융아연 도금강판의 제조 및 냉각장치를 개략적으로 보인 예시도,3 is an exemplary view schematically showing an apparatus for producing and cooling an alloyed hot dip galvanized steel sheet according to the present invention;
도 4는 본 발명의 냉각방법에 따른 냉각속도를 비교한 그래프.4 is a graph comparing the cooling rate according to the cooling method of the present invention.
* 도면의 주요 부분에 대한 부호의 설명 *Explanation of symbols on the main parts of the drawings
10 : 도금조, 50 : 합금화열처리로,10: plating bath, 50: alloying heat treatment furnace,
56 : 노즐, 60 : 워터탱크,56 nozzle, 60 water tank,
70 : 중간롤, 90 : 수공급부.70: middle roll, 90: water supply part.
이하에서는, 본 발명에 따른 바람직한 일 실시예를 첨부도면에 의거하여 보다 상세하게 설명한다.Hereinafter, a preferred embodiment according to the present invention will be described in more detail on the basis of the accompanying drawings.
도 3은 본 발명에 따른 도금강판 냉각방법을 설명하기 위한 냉각장치의 구성을 개략적으로 도시한 것이다.Figure 3 schematically shows the configuration of a cooling apparatus for explaining a plated steel sheet cooling method according to the present invention.
도 3을 참조하면, 냉연강판(S)을 용융아연 도금하기 위한 도금조(10)가 구비되고, 도금조(10)의 직상방에는 도금량을 조절하기 위한 에어나이프(20)가 구비되며, 도금된 냉연강판(S)을 이송하기 위한 상부롤(30) 및 가이드롤(40)이 구비된다.Referring to FIG. 3, a plating bath 10 for hot-dip galvanizing of the cold rolled steel sheet S is provided, and an air knife 20 for adjusting the plating amount is provided directly above the plating bath 10, and plating is performed. The upper roll 30 and the guide roll 40 for conveying the cold rolled steel sheet (S) is provided.
가이드롤(40)의 직하방에는 합금화열처리로(50)가 구비되며, 상기 가이드롤(40)은 냉연강판(S)이 상기 합금화열처리로(50)로 정확하게 센터링되어 장입될 수 있도록 안내하여 준다.Directly below the guide roll 40 is provided with an alloying heat treatment furnace 50, the guide roll 40 guides the cold rolled steel (S) to be accurately centered and charged into the alloying heat treatment furnace (50). .
즉, 강판이 후술할 워터탱크(60) 내에서 수냉각될 때에 사행되는 것을 방지하여 준다.That is, the steel sheet is prevented from meandering when water-cooled in the water tank 60 which will be described later.
합금화열처리로(50)의 하측에는 냉각수가 저수된 워터탱크(60)가 구비되며, 상기 워터탱크(60)의 일측방에는 냉각된 냉연강판(S)의 형상을 균일하게 하기 위한조질압연기(80)가 구비된다.A water tank 60 in which cooling water is stored is provided below the alloy heat treatment furnace 50, and in one side of the water tank 60, a rough rolling mill 80 for uniformizing the shape of the cooled cold rolled steel sheet S. ) Is provided.
워터탱크(60)와 조질압연기(80) 사이에는 중간롤(70)이 구비되어 냉연강판(S)의 원활한 이송을 도모하고, 상기 중간롤(70)과 워터탱크(60) 사이에는 워터탱크(60)를 거쳐 급냉되어 이송되던 냉연강판(S)을 건조시키기 위한 블로우어(52) 및 상기 블로우어(52)를 통해 공급된 공기를 분사하는 노즐(56)이 구비되며, 상기 노즐(56)은 노즐헤더(54)에 고정된다.An intermediate roll 70 is provided between the water tank 60 and the temper rolling mill 80 to facilitate smooth transfer of the cold rolled steel S, and a water tank between the intermediate roll 70 and the water tank 60. A blower 52 for drying the cold rolled steel sheet S, which has been quenched and transported through 60, and a nozzle 56 for spraying the air supplied through the blower 52 are provided, and the nozzle 56 is provided. Is fixed to the nozzle header 54.
상기 워터탱크(60)의 상단면 일측에는 배출배관(62)이 설치되고, 상기 배출배관(62)상에는 배기팬(64) 및 배기팬(64)에 의해 배출된 냉각수 및 공기의 혼합액을 서로 분리시키는 기액분리기(66)가 상기 배기팬(64)의 상측에 설치된다.A discharge pipe 62 is installed at one side of the upper surface of the water tank 60, and the mixed liquid of the coolant and air discharged by the exhaust fan 64 and the exhaust fan 64 is separated from each other on the discharge pipe 62. The gas-liquid separator 66 is installed above the exhaust fan 64.
분리된 기체는 대기로 방출되고, 액체는 순환배관(98)으로 이동된다.The separated gas is released to the atmosphere, and the liquid is moved to the circulation pipe (98).
순환배관(98)은 워터탱크(98)의 측면에 배설되어 워터탱크(60)에 저수된 냉각수를 순환시키는 것으로, 그 일부에는 펌프(92), 열교환기(94) 및 필터(96)가 장착된다.The circulation pipe 98 is disposed at the side of the water tank 98 to circulate the coolant stored in the water tank 60, and a part thereof is equipped with a pump 92, a heat exchanger 94, and a filter 96. do.
본 발명은 이와 같은 구성으로 이루어진 냉각장치를 통해 용융아연 도금된 냉연강판을 적절하게 냉각시키는 방법을 제공하는 것으로, 그 냉각방법은 다음과 같다.The present invention provides a method for properly cooling a hot-dip galvanized cold rolled steel sheet through a cooling device having such a configuration, and the cooling method is as follows.
먼저, 냉연강판(S)을 용융아연 도금조(10)에 통과시켜 도금을 행한 후 에어나이프(20)를 거쳐 적정한 도금량이 부착되도록 도금량을 조절한다.First, the cold rolled steel sheet (S) is passed through the molten zinc plating tank 10 to perform plating, and then the plating amount is adjusted to attach an appropriate plating amount through the air knife 20.
이어, 곧바로 상부롤(30)까지 진입시킨 후 가이드롤(40)을 통해 센터링을 유지한 채 연속적으로 직하강시켜 합금화열처리로(50)로 투입시킨다.Subsequently, it immediately enters the upper roll 30 and continuously descends continuously while maintaining the centering through the guide roll 40 to be introduced into the alloying heat treatment furnace 50.
즉, 용융아연이 도금된 강판(S)을 470~560℃의 범위로 열처리로(50)에서 가열하여 합금화 열처리하게 된다.That is, the molten zinc plated steel sheet (S) is heated in the heat treatment furnace 50 in the range of 470 ~ 560 ℃ alloy is heat treatment.
이어, 합금화 열처리된 도금강판(S)을 워터탱크(60)에 침적시켜 냉각수와 강판이 직접 접촉되도록 함으로써 급냉시킨다.Subsequently, the alloyed heat-treated plated steel sheet (S) is immersed in the water tank 60 to quench by direct contact with the cooling water and the steel sheet.
이때, 강판의 온도를 150℃ 이하로 워터퀘칭(WATER QUENCHING)하여 냉각하게 된다.At this time, the temperature of the steel sheet is cooled by water quenching (WATER QUENCHING) to 150 ° C or less.
이와 같이 470~560℃의 범위에서 열처리된 강판을 150℃이하로 급냉하는 것은 도금강판이 열처리된 후 충분히 냉각되지 않으면 아연입자의 밀착성이 완전하지 못하여 표층탈락현상이 유발되거나 혹은 가공시 분말형태로 떨어져 나가는 파우더링 현상이 발생되기 때문에 최대한 급냉각되어야 한다.As described above, quenching the steel sheet heat-treated in the range of 470 to 560 ° C. or lower at 150 ° C. or less may cause surface dropout due to insufficient adhesion of the zinc particles if the plated steel sheet is not sufficiently cooled after the heat treatment. It must be quenched as much as possible, as it will cause powdering to fall off.
즉, 합금화가 진행되는 과정에서 150℃를 기준으로 그 이하일 때 철이 아연속으로 확산되지 못하기 때문에 열처리된 강판을 최소한 150℃ 이하로 급냉하여 철의 확산을 막음으로써 과합금화를 방지할 수 있도록 하기 위함이다.That is, since the iron is not diffused into the zinc at 150 ° C or lower during the alloying process, the heat-treated steel sheet is quenched to at least 150 ° C or lower to prevent the diffusion of iron to prevent over alloying. For sake.
또한, 상기한 최소한의 온도로 급냉시키기 위해서는 최소한 냉각수의 온도가 80℃ 이하로 유지되어야만 하고, 냉각효율을 극대화시키기 위해서는 냉각속도를 최소 100℃/초에서 최대 250/초를 유지하여야 한다.In addition, in order to quench to the minimum temperature described above, the temperature of the cooling water should be maintained at 80 ° C. or lower at a minimum, and the cooling rate should be maintained at a maximum of 250 ° C. at a minimum of 100 ° C./sec to maximize the cooling efficiency.
만약, 냉각수의 온도가 80℃를 넘어서게 되면 강판을 150℃ 이하로 급냉시킬 수 없어 철의 확산을 막지못하므로 과합금화가 유발되며, 냉각속도를 100℃/초 이하로 하게 되면 기존의 공냉보다 약간 우수한 냉각성만을 보이고 냉각속도를 250℃/초 이상으로 유지하게 되면 과냉각이 이루어지기 때문에 상기한 정도의 온도를 유지함이 바람직하다.If the temperature of the cooling water exceeds 80 ℃, the steel sheet cannot be quenched to 150 ℃ or less, which prevents the diffusion of iron, causing over alloying. If the cooling rate is less than 100 ℃ / sec, it is slightly lower than the existing air cooling. It is preferable to maintain the above-mentioned temperature because only superb cooling performance is observed and the cooling rate is maintained at 250 ° C./sec or more, so that supercooling is performed.
급냉이 완료되면 중간롤(70)에 의해 강판의 형상을 교정하기 위한 조질압연기(80)로 이송된다.When quenching is completed, the intermediate roll 70 is transferred to the temper mill 80 for correcting the shape of the steel sheet.
본 발명의 냉각방법에 따르면 직접 냉각수에 강판을 침적시킴으로써 냉각속도를 최대 250℃/초 까지 향상시킬 수 있으며, Γ상의 두께도 0.05㎛ 이하로 크게 감소시킬 수 있어 가공성이 매우 우수하게 된다.According to the cooling method of the present invention, by directly depositing the steel plate in the cooling water can improve the cooling rate up to 250 ℃ / sec, the thickness of the Γ phase can also be greatly reduced to 0.05㎛ or less, the workability is very excellent.
반면에, 종래 포그냉각에 따른 냉각속도는 약 20~40℃/초의 범위내로 제한되기 때문에 합금 도금층의 Γ상 두께가 0.5㎛ 정도 밖에 확보되지 못하게 된다.On the other hand, since the cooling rate according to the conventional fog cooling is limited in the range of about 20 ~ 40 ℃ / sec, the Γ phase thickness of the alloy plating layer can be secured only about 0.5㎛.
따라서, 본 발명의 냉각방법은 두께가 0.2~2.3mm 정도인 냉연강판에 특히 적합하다.Therefore, the cooling method of the present invention is particularly suitable for cold rolled steel sheet having a thickness of about 0.2 ~ 2.3mm.
이하, 상술한 바와 같은 본 발명의 냉각방법에 따른 실시예에 대하여 설명한다.Hereinafter, an embodiment according to the cooling method of the present invention as described above will be described.
[실시예]EXAMPLE
두께가 1.0mm이고, 폭이 1200mm인 냉연강판을 편면 도금부착량이 각각 60g/㎡이 되도록 용융아연 도금한 후, 550℃의 온도로 약 12초 동안 합금화 열처리 하였다. 열처리된 강판을 공냉, 포그냉각, 수냉각의 방법으로 각각 냉각하여 과합금화를 방지하였으며, 공냉의 경우는 공기의 유량을 시간당 130,000m3, 포그냉각의 경우는 공기 유량을 시간당 80,000m3, 그리고 수냉의 경우는 냉각수의 유량을 시간당 150m3정도로 조절하였다. 또한, 본 발명의 수냉방식의 경우는 워터탱크(60)의 용량을 450m3으로 하고, 냉각수의 순환량은 분당 1~30m3으로 펌핑하여 워터탱크(60)내의 온도를 평균 80℃ 이하로 유지하였다. 이렇게 하여 제조된 합금화 용융아연 도금강판에 대하여 내파우더링성, 가공성, 아연 픽업성 및 합금화도를 측정하였고, 그 결과를 도 4 및 하기한 표 1에 나타내었다.A cold rolled steel sheet having a thickness of 1.0 mm and a width of 1200 mm was hot-dipped galvanized so that the amount of single-sided plating was 60 g / m 2, and then subjected to alloy heat treatment at a temperature of 550 ° C. for about 12 seconds. The heat-treated steel sheet was cooled by air cooling, fog cooling, or water cooling to prevent over alloying.In the case of air cooling, the air flow rate was 130,000m 3 per hour, in the case of fog cooling, the air flow rate was 80,000m 3 , and In the case of water cooling, the flow rate of the cooling water was adjusted to about 150 m 3 per hour. In addition, in the water cooling method of the present invention, the capacity of the water tank 60 was set to 450 m 3 , and the circulation amount of the cooling water was pumped at 1 to 30 m 3 per minute to maintain the temperature in the water tank 60 at an average of 80 ° C. or less. . Powdered resistance, workability, zinc pick-up and alloying degree of the alloyed hot-dip galvanized steel sheet thus prepared were measured, and the results are shown in FIG. 4 and Table 1 below.
이때, 내파우더링성은 제조된 강판의 표면에 테이프를 붙이고 180도 굽힘시험을 실시하여 테이프에 묻어나온 도금 분말량을 측정하여 평가하였으며, 아연 픽업성은 상기 강판의 표면에 픽업마크 흔적을 단위 면적당 발생정도로 평가하였고, 합금화 균일성은 합금화도의 편차로 상호 비교하여 평가하였으며, 가공성은 만능시험기에 의해 가공에 필요한 최대 소요 힘의 양을 분석하였고, 형상은 표면 평탄도를 육안으로 관찰하였다.At this time, the powder resistance was evaluated by measuring the amount of plating powder buried in the tape by attaching a tape to the surface of the manufactured steel sheet and performing a 180 degree bending test, and the zinc pick-up property generated a pickup mark trace on the surface of the steel sheet per unit area. The degree of alloying uniformity was evaluated by comparing the degree of alloying uniformity with the variation of degree of alloying. The workability was analyzed by the universal testing machine for the maximum required force, and the shape of the surface was visually observed.
[표 1]TABLE 1
(여기에서, 1(우수) <-----> 5(불량)을 나타낸다)(Here, 1 (excellent) <-----> 5 (defect) is shown)
상기 표 1에서와 같이, 냉각수에 의해 급냉하는 경우 냉각속도는 100~250℃/초 로 대단히 높은 반면, 포그냉각과 공냉의 경우는 50℃/초 이하로 매우 낮은 것을 알 수 있다.As shown in Table 1, when quenched by the cooling water, the cooling rate is very high as 100 ~ 250 ℃ / second, while in the case of fog cooling and air cooling it can be seen that very low as 50 ℃ / second or less.
또한, 비교예의 수냉각에서 순환수의 냉각수 유량이 1m3/분 이하인 경우 열교환기가 적정 냉각을 위한 용량을 초과하여 워터탱크(60) 내의 냉각수의 온도가 150℃ 이상 고온으로 유지되며 이때 강판의 냉각속도는 50℃/초 이하가 되므로 냉각이 불충분하게 된다.In addition, when the cooling water flow rate of the circulating water is 1 m 3 / min or less in the water cooling of the comparative example, the heat exchanger exceeds the capacity for proper cooling, and the temperature of the cooling water in the water tank 60 is maintained at a high temperature of 150 ° C. or higher. The speed will be 50 ° C / sec or less, resulting in insufficient cooling.
따라서, 본 발명에 따른 수냉각에 의한 냉각방식이 종래 공냉 및 포그냉각에 비해 월등히 우수한 냉각효과를 나타내며, 그에 따라 제조된 강판은 내파우더링성 뿐만 아니라 가공성 및 아연픽업성에 있어서도 매우 우수함을 알 수 있었다.Therefore, the cooling method by the water cooling according to the present invention shows an excellent cooling effect compared to the conventional air cooling and fog cooling, it was found that the steel sheet produced according to the present invention is very excellent in workability and zinc pick-up as well as powder resistance. .
한편, 수냉각을 적용하였더라도 순환수량이 적으면 발명예 보다도 효과가 적게 나타났으며 순환수량을 현저히 크게 하면 냉각소도는 급증하나 강판의 형상이 악화되는 현상이 유발되므로 적정 냉각온도를 유지하기 위해서는 1~30m3/분 이상 유지할 필요가 있었다.On the other hand, even if the water cooling is applied, if the amount of circulating water is less effective than the invention example, and if the amount of circulating water is significantly increased, the cooling power is increased, but the shape of the steel sheet is deteriorated, so as to maintain the proper cooling temperature 1 Needed to hold at least ~ 30m 3 / min.
이상에서 상세히 설명한 바와 같이, 본 발명에 따른 냉각방법은 용융아연 도금된 냉연강판을 합금화 처리한 후 곧바로 냉각수에 침적시켜 수냉각함으로써 도금층의 과합금화를 방지하고 내파우더링성 뿐만 아니라 아연픽업성, 가공성이 우수한 합금화 용융아연 도금강판을 제조할 수 있는 커다란 효과를 제공한다.As described above in detail, the cooling method according to the present invention prevents over alloying of the plating layer by water-cooling by immersing the hot-dip galvanized cold rolled steel sheet in water and immediately immersing it in coolant to prevent over-alloying of the plating layer, as well as zinc picking resistance and processability. It provides a great effect to produce this excellent alloyed hot-dip galvanized steel sheet.
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| KR1020000061303A KR20020030936A (en) | 2000-10-18 | 2000-10-18 | Cooling method of melting-zinc coated steel having easy moldability |
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| KR101716641B1 (en) | 2015-11-06 | 2017-03-15 | 김선홍 | Apparatus For Making Coffee |
Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH04276054A (en) * | 1991-03-05 | 1992-10-01 | Mitsubishi Heavy Ind Ltd | Manufacture of galvanized steel sheet |
| KR100286667B1 (en) * | 1996-07-26 | 2001-04-16 | 이구택 | Manufacturing method of galvanized steel sheet |
| KR100362671B1 (en) * | 1998-12-22 | 2003-03-03 | 주식회사 포스코 | Cooling method of alloyed hot-dip galvanized steel sheet and cooling apparatus used therein |
-
2000
- 2000-10-18 KR KR1020000061303A patent/KR20020030936A/en not_active Application Discontinuation
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH04276054A (en) * | 1991-03-05 | 1992-10-01 | Mitsubishi Heavy Ind Ltd | Manufacture of galvanized steel sheet |
| KR100286667B1 (en) * | 1996-07-26 | 2001-04-16 | 이구택 | Manufacturing method of galvanized steel sheet |
| KR100362671B1 (en) * | 1998-12-22 | 2003-03-03 | 주식회사 포스코 | Cooling method of alloyed hot-dip galvanized steel sheet and cooling apparatus used therein |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| KR101716641B1 (en) | 2015-11-06 | 2017-03-15 | 김선홍 | Apparatus For Making Coffee |
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