KR100241307B1 - The method of making zn alloying coating sheet - Google Patents
The method of making zn alloying coating sheet Download PDFInfo
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- KR100241307B1 KR100241307B1 KR1019950056451A KR19950056451A KR100241307B1 KR 100241307 B1 KR100241307 B1 KR 100241307B1 KR 1019950056451 A KR1019950056451 A KR 1019950056451A KR 19950056451 A KR19950056451 A KR 19950056451A KR 100241307 B1 KR100241307 B1 KR 100241307B1
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- South Korea
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- steel sheet
- hot
- plating
- galvanized steel
- dip galvanized
- Prior art date
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- 238000005275 alloying Methods 0.000 title claims abstract description 27
- 238000004519 manufacturing process Methods 0.000 title claims abstract description 18
- 239000011248 coating agent Substances 0.000 title description 4
- 238000000576 coating method Methods 0.000 title description 4
- 238000007747 plating Methods 0.000 claims abstract description 65
- 229910001335 Galvanized steel Inorganic materials 0.000 claims abstract description 24
- 239000008397 galvanized steel Substances 0.000 claims abstract description 24
- 229910001209 Low-carbon steel Inorganic materials 0.000 claims abstract description 10
- 238000005246 galvanizing Methods 0.000 claims abstract description 10
- 238000000034 method Methods 0.000 claims abstract description 10
- 238000000137 annealing Methods 0.000 claims abstract description 3
- 229910052742 iron Inorganic materials 0.000 claims description 14
- 239000010936 titanium Substances 0.000 claims description 9
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 claims description 6
- 239000010955 niobium Substances 0.000 claims description 6
- 229910052719 titanium Inorganic materials 0.000 claims description 5
- 239000002131 composite material Substances 0.000 claims description 3
- 229910052758 niobium Inorganic materials 0.000 claims description 2
- 229910000831 Steel Inorganic materials 0.000 abstract description 15
- 239000010959 steel Substances 0.000 abstract description 15
- 229910045601 alloy Inorganic materials 0.000 abstract description 9
- 239000000956 alloy Substances 0.000 abstract description 9
- RJSRQTFBFAJJIL-UHFFFAOYSA-N niobium titanium Chemical compound [Ti].[Nb] RJSRQTFBFAJJIL-UHFFFAOYSA-N 0.000 abstract description 4
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 42
- 239000010410 layer Substances 0.000 description 27
- 229910052782 aluminium Inorganic materials 0.000 description 6
- 238000010438 heat treatment Methods 0.000 description 6
- 239000000463 material Substances 0.000 description 6
- 150000001875 compounds Chemical class 0.000 description 5
- 239000011701 zinc Substances 0.000 description 5
- 238000000227 grinding Methods 0.000 description 4
- 229910000765 intermetallic Inorganic materials 0.000 description 4
- 238000006243 chemical reaction Methods 0.000 description 3
- 230000008569 process Effects 0.000 description 3
- 239000006104 solid solution Substances 0.000 description 3
- 229910052725 zinc Inorganic materials 0.000 description 3
- CWYNVVGOOAEACU-UHFFFAOYSA-N Fe2+ Chemical compound [Fe+2] CWYNVVGOOAEACU-UHFFFAOYSA-N 0.000 description 2
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 description 2
- HCHKCACWOHOZIP-UHFFFAOYSA-N Zinc Chemical compound [Zn] HCHKCACWOHOZIP-UHFFFAOYSA-N 0.000 description 2
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 2
- 230000015572 biosynthetic process Effects 0.000 description 2
- 238000009792 diffusion process Methods 0.000 description 2
- 230000005484 gravity Effects 0.000 description 2
- 229910018072 Al 2 O 3 Inorganic materials 0.000 description 1
- 229910018137 Al-Zn Inorganic materials 0.000 description 1
- 229910018573 Al—Zn Inorganic materials 0.000 description 1
- 238000003287 bathing Methods 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 239000011247 coating layer Substances 0.000 description 1
- 239000010960 cold rolled steel Substances 0.000 description 1
- 230000000052 comparative effect Effects 0.000 description 1
- 238000005260 corrosion Methods 0.000 description 1
- 230000007797 corrosion Effects 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- 230000000593 degrading effect Effects 0.000 description 1
- 238000000151 deposition Methods 0.000 description 1
- 230000008021 deposition Effects 0.000 description 1
- 230000002542 deteriorative effect Effects 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000004070 electrodeposition Methods 0.000 description 1
- 238000007654 immersion Methods 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 238000002347 injection Methods 0.000 description 1
- 239000007924 injection Substances 0.000 description 1
- KFZAUHNPPZCSCR-UHFFFAOYSA-N iron zinc Chemical compound [Fe].[Zn] KFZAUHNPPZCSCR-UHFFFAOYSA-N 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 229910052759 nickel Inorganic materials 0.000 description 1
- 238000001556 precipitation Methods 0.000 description 1
- 230000009257 reactivity Effects 0.000 description 1
- 230000009467 reduction Effects 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
- 239000000243 solution Substances 0.000 description 1
- 230000008961 swelling Effects 0.000 description 1
- LEONUFNNVUYDNQ-UHFFFAOYSA-N vanadium atom Chemical compound [V] LEONUFNNVUYDNQ-UHFFFAOYSA-N 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
- C23C2/04—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
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C33/00—Making ferrous alloys
- C22C33/04—Making ferrous alloys by melting
- C22C33/06—Making ferrous alloys by melting using master alloys
-
- 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
-
- 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
Landscapes
- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Mechanical Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Physics & Mathematics (AREA)
- Oil, Petroleum & Natural Gas (AREA)
- Thermal Sciences (AREA)
- Coating With Molten Metal (AREA)
Abstract
본 발명은 가전제품 및 자동차용 강판등으로 널리 사용되는 합금화 용융아연 도금강판을 제조하는 방법에 관한 것으로서, 보다 상세하게는 가공성 및 표면외관이 우수한 합금화 용융아연 도금강판을 제조하는 방법에 관한 것이다.The present invention relates to a method for producing an alloyed hot-dip galvanized steel sheet widely used in home appliances and automotive steel plates, and more particularly, to a method for producing an alloyed hot-dip galvanized steel sheet excellent in workability and surface appearance.
본 발명의 표면외관 및 가공성이 우수한 합금과 용융아연 도금강판제조법은 티타늄-니오븀 복합첨가 극저탄소강을 소둔하고 455-465℃ 범위에서 도금후 합금화처리하여 합금화 용융아연도금강판을 제조하는 방법에 있어서, 상기 용융아연도금시 Al 성분이 0.13-0.14wt.%, Fe 성분이 0.04wt.% 이하인 도금욕에서 용융아연 도금후, 480-520℃ 온도범위에서 합금화처리하는 것을 특징으로 한다.In the method of producing an alloy and hot-dip galvanized steel sheet having excellent surface appearance and workability of the present invention, an annealing titanium-niobium compound-added ultra low carbon steel is alloyed after plating in the range of 455-465 ° C. to produce an alloyed hot-dip galvanized steel sheet. In the hot dip galvanizing, the Al component is 0.13-0.14 wt.% And the Fe component is 0.04 wt.% Or less in the plating bath after hot dip galvanizing, characterized in that the alloying treatment at a temperature range of 480-520 ℃.
Description
본 발명은 가전제품 및 자동차용 강판등으로 널리 사용되는 합금화 용융아연 도금강판을 제조하는 방법에 관한 것으로서, 보다 상세하게는 가공성 및 표면외관이 우수한 합금화 용융아연 도금강판을 제조하는 방법에 관한 것이다.The present invention relates to a method for producing an alloyed hot-dip galvanized steel sheet widely used in home appliances and automotive steel plates, and more particularly, to a method for producing an alloyed hot-dip galvanized steel sheet excellent in workability and surface appearance.
용융아연 도금제품중 합금화 용융아연 도금강판은 용접성 및 도장성이 우수하여 가전제품, 자동차용 강판으로 널리 사용되고 있다. 자동차용 강판의 적용에 있어서는 고가공성과 적정 강도가 요구되며 판재 공급 확대를 위하여 강판의 도금후 표면외관이 우수하여야 한다. 특히 자동차 외판재로 사용시 강판 표면에 흠이나 미세 화합물 등이 존재하지 않아야 한다.Among the hot-dip galvanized products, alloyed hot-dip galvanized steel sheet has excellent weldability and paintability and is widely used for home appliances and automotive steel sheets. In the application of automotive steel plate, high workability and proper strength are required, and the surface appearance after plating of steel plate should be excellent for expansion of plate supply. In particular, when used as an automobile exterior material, there should be no scratches or fine compounds on the surface of the steel sheet.
일반적으로 합금화 용융아연 도금강판은 연속 용융아연 도금라인에서 아연도금욕을 통과한 스트립을 합금화열처리하여 제조하게 되며 가공용 강판 제조를 위하여 티타늄(Ti) 혹은 티타늄(Ti)-니오븀(Nb) 복합첨가 극저탄소강을 소재로서 사용한다.In general, alloyed hot-dip galvanized steel sheet is manufactured by alloying heat treatment of a strip passed through a galvanizing bath in a continuous hot-dip galvanizing line, and is a titanium (Ti) or titanium (ni) -nibium (Nb) composite addition pole for manufacturing a steel sheet for processing. Low carbon steel is used as the material.
한편 도금밀착성을 확보하기 위하여 도금욕내에 적정량의 Al을 첨가하는데, 스트립이 도금욕에 인입되어 도금될 때 Al과 우선 반응하여 Fe-Al계 2원화합물 혹은 Fe-Al-Zn계 3원화합물의 아주 얇고 치밀한 합금층을 생성시킨다. 이 합금층은 합금화열처리시 소지철에서 아연 도금층으로의 확산을 억제시키는 역할을 하며 상기 합금층이 존재함에 따라 부분합금화 또는 미합금화 부분이 발생될 수 있다.On the other hand, an appropriate amount of Al is added to the plating bath in order to secure plating adhesion. When the strip enters the plating bath and is plated, it reacts first with Al to form a Fe-Al binary compound or a Fe-Al-Zn tertiary compound. Produces a very thin and dense alloy layer. The alloy layer serves to suppress the diffusion from the base iron to the galvanized layer during the alloying heat treatment, and the partial alloy or unalloyed portion may be generated as the alloy layer is present.
또한 연속적인 작업으로 도금욕내 스트립이 계속 통과되면서 Al이 계속 소비되는 한편 소지철인 Fe가 도금욕내로 용출되어 Al, Zn과 결합하여 금속간화합물(Dross)을 형성한다. 이러한 드로스가 도금욕내에 부유하면서 도금이 진행되는 스트립에 부착하여 도금층 표면을 연화시키기 때문에 Al, Fe 원소의 농도관리에 주의하여야 한다.In addition, as the strip continuously passes through the plating bath, Al is continuously consumed, while Fe, a ferrous iron, is eluted into the plating bath to combine with Al and Zn to form an intermetallic compound (Dross). Care should be taken in the concentration control of Al and Fe elements because these drosses float in the plating bath and adhere to the strip where the plating proceeds, thereby softening the surface of the plating layer.
상기 강종에서 제조된 합금화 용융아연 도금 강판은 가공시 도금층이 박리되면 파우더링(Powdering) 및 플레이킹(Flaking) 현상이 발생하여 가공성은 저하하며, 이를 개선하기 위하여 강종, 전처리, 용융도금 조건, 합금화 열처리 조건 등의 연구가 활발히 진행중에 있다.The alloyed hot-dip galvanized steel sheet manufactured from the steel grades has powdering and flaking phenomena when the plating layer is peeled off during processing, thereby decreasing workability. In order to improve the steel grade, pretreatment, hot-dip galvanizing conditions, alloying Research on heat treatment conditions is actively underway.
합금화 용융아연 도금강판의 가공성 향상과 관련한 공지기술로는 용융아연 도금욕중에 알루미늄을 미량 첨가시켜 아연도금후 합금화처리한 일본 특허공개 소56-13170호, 아연도금전 강판에 철, 니켈 등을 먼저 도금한 후 아연도금 및 합금화처리한 일본 특허공개 소58-104163호, 일본 특허공개 소60-110859호 등이 알려져 있다.Known techniques related to the improvement of workability of alloyed hot-dip galvanized steel sheet include Japanese Patent Publication No. 56-13170, which is alloyed after galvanizing by adding a small amount of aluminum in a hot-dip galvanizing bath, and iron, nickel, etc., on a pre-galvanized steel sheet. Japanese Patent Laid-Open No. 58-104163, Japanese Patent Laid-Open No. 60-110859, and the like which have been plated and galvanized and alloyed are known.
또한, 가공성 및 도장성이 우수한 합금화 용융아연 도금강판의 공지기술로는 도금욕중 바나듐(V)을 첨가하여 도금 및 합금화처리 후 편면에 유기피막을 0.1-4.0g/m2피복시킨 일본 특허 공개 평5-44006호 등을 들 수 있다.In addition, as a well-known technique for alloying hot-dip galvanized steel sheet having excellent workability and paintability, Japanese patent publication in which an organic film is coated 0.1-4.0 g / m 2 on one side after plating and alloying treatment by adding vanadium (V) in a plating bath. Hei 5-44006 etc. are mentioned.
그러나, 상기 일본 특허 공개 소56-13470호에 개시된 기술의 경우에는 가공성은 어느정도 향상되지만, 성형성이 나빠지고 도장후의 내식성이 떨어지는 문제점이 있다.However, in the technique disclosed in Japanese Patent Application Laid-Open No. 56-13470, workability is somewhat improved, but there is a problem in that moldability is poor and corrosion resistance after coating is inferior.
또한 상기 일본 특허공개 소58-104163호 및 공개 소60-110859호의 경우에는 별도의 전처리 공정이 추가되어야 하므로 제조공정이 복잡할 뿐만 아니라 제조비용의 증가를 가져오는 문제점이 있다.In addition, in the case of Japanese Patent Laid-Open No. 58-104163 and Japanese Patent Laid-Open No. 60-110859, a separate pretreatment process must be added, which leads to a complicated manufacturing process and an increase in manufacturing cost.
더우기, 상기 일본 특허공개 평5-44006호의 경우에는 별도의 후처리 공정이 추가되어야 하므로 제조공정이 복잡할 뿐만 아니라 제조비용의 증가를 가져오게 되는 문제점이 있다.In addition, in the case of Japanese Patent Laid-Open No. 5-44006, a separate post-treatment process has to be added, and thus there is a problem that the manufacturing process is not only complicated but also increases the manufacturing cost.
따라서 본 발명은 도금욕내 Al, Fe 량이 조정된 도금욕에서 도금 및 가스분사에 의한 부착량 조정을 거쳐 적정 온도에서의 합금화처리를 실시하여 도금층 표면 외관이 양호하고 프레스 가공시 내파우더링성이 우수한 합금화 용융아연 도금강판을 제조할 수 있는 방법을 제공하는데 그 목적이 있다.Therefore, the present invention performs alloying treatment at an appropriate temperature by adjusting the adhesion amount by plating and gas injection in the plating bath in which the amount of Al and Fe in the plating bath is adjusted, so that the surface appearance of the coating layer is good and the alloying melt has excellent powdering resistance during press working. It is an object of the present invention to provide a method for manufacturing a galvanized steel sheet.
상기 목적을 달성하기 위한 본 발명은 티타늄(Ti)-니오븀(Nb) 복합첨가 극저탄소강 소재를 용융아연 도금욕에 침지하여 도금후 합금화처리하여 용융아연 합금화 도금강판을 제조하는 방법에 있어서, 도금욕내 전 Al 함량이 0.12-0.14%, 전 Fe 함량이 0.04% 이하로 관리되고, 480-520℃의 온도범위에서 합금화처리하여 드로스가 부착되지 않는 표면외관이 양호하고 가공성이 우수한 합금화 용융아연 도금강판을 제조하는 방법에 관한 것이다.In order to achieve the above object, the present invention provides a method of manufacturing a hot-dip galvanized steel sheet by plating a titanium (Ti) -niobium (Nb) -added ultra low carbon steel material by immersion in a hot dip galvanizing bath and then performing alloying after plating. Alloyed hot-dip galvanized steel sheet with good surface appearance without dross by alloying in the temperature range of 480-520 ℃ and alloying in the temperature range of 480-520 ℃ with Al content 0.12-0.14% before bathing It relates to a method of manufacturing.
이하에서는 양호한 실시예와 관련하여 본 발명을 상세하게 설명한다.Hereinafter, the present invention will be described in detail with reference to the preferred embodiments.
본 발명은 합금화 용융아연 도금강판 제조시 강판표면에 미세 화합물 즉, 드로스가 부착되지 않는 적정 도금욕 조성범위를 유지하고 가공성 향상을 위해 합금화처리 조건을 적정 제어하는 것을 그 요지로 하고 있다.The present invention is to maintain the proper plating bath composition range in which fine compounds, that is, dross does not adhere to the surface of the steel sheet during the production of alloyed hot-dip galvanized steel sheet and to properly control the alloying treatment conditions in order to improve workability.
드로스(Dross)는 도금욕으로 인입되는 스트립(Strip) 및 도금욕내 존재하는 각종 롤구동부위에서 용출되는 Fe 성분과 합금층이 생성하는 것을 방지하기 위해 첨가되는 미량의 Al 그리고 도금욕 주성분인 Zn 성분과 반응하여 생성되는데, 아연 도금욕 비중보다 낮은 상부(Top) 드로스(Fe2Al5, ZnO, Al2O3)와 아연도금욕 비중보다 무거운 하부(Bottom) 드로스(FeZn13, FeZn7)로 구분된다. 도금욕중 Al 조정기술은 매우 중요하여 Al 농도변화는 드로스 생성량과 밀접한 관계에 있다.Dross is a small amount of Al added to prevent the formation of the Fe component eluted from various strip driving parts existing in the plating bath and various roll driving parts in the plating bath and the alloy layer, and the Zn component which is the main component of the plating bath. It is produced by reaction with the top dross (Fe 2 Al 5 , ZnO, Al 2 O 3 ) lower than the specific gravity of the zinc plating bath and the bottom dross (FeZn 13 , FeZn 7 ) heavier than the specific gravity of the zinc plating bath. ). Al adjustment technology in the plating bath is very important, so the Al concentration change is closely related to the dross production.
즉, 도금욕내 Al은 인입되는 스트립과 우선 반응하여 도금층내 Al로 소비되며, 이때 도금층내 Al 함량은 도금욕내 Al 보다 항상 많이 검출된다. 또한, 도금욕내 Fe와 반응하여 Fe2Al5혹은 Fe2Al5Zn 형태의 금속간화합물 즉 상부 드로스를 형성한다.That is, Al in the plating bath is first reacted with the incoming strip and consumed as Al in the plating layer, wherein the Al content in the plating layer is always detected more than Al in the plating bath. In addition, it reacts with Fe in the plating bath to form an intermetallic compound, that is, an upper dross, in the form of Fe 2 Al 5 or Fe 2 Al 5 Zn.
따라서 유효 Al은 상기와 같이 상부 드로스와 스트립의 도금층내에서 반응한 Al량을 제외하고 반응하지 않은채 도금욕내에 존재하는 고용 Al을 말하며 다음 식(1)으로 나타낼 수 있다.Therefore, effective Al refers to solid solution Al existing in the plating bath without reacting, except for the amount of Al reacted in the plating layer of the upper dross and the strip as described above, and may be represented by the following equation (1).
유효(고용)Al 농도=전 Al 농도-석출(도금욕, 도금층) Al 농도…(1)Effective (Solution) Al Concentration = Total Al Concentration-Precipitation (Plating Bath, Plating Layer) Al Concentration. (One)
상기 유효 Al 농도식과 마찬가지로 도금욕중 유효 Fe 농도로 아래와 같이 식(2)으로 표시할 수 있다. 이때 Fe 농도는 항상 스트립이 도금욕을 통과하므로 고용 한도량보다 많은 Fe가 도금욕내 과포화 상태로 존재한다.Similarly to the effective Al concentration formula, the effective Fe concentration in the plating bath can be represented by the following formula (2). At this time, the Fe concentration is always through the plating bath, so more Fe is present in the plating bath in a supersaturated state.
유효(고용) Fe 농도=전 Fe 농도-석출 Fe 농도…(2)Effective (Solid) Fe Concentration = Total Fe Concentration-Precipitated Fe Concentration... (2)
도금욕중 Al 함량은 용융아연 도금강판을 생산할 때 전 Al량 기준으로 0.15-0.20중량% 범위로 첨가되나 합금화 용융아연 도금강판의 경우 도금층의 합금화를 촉진시키기 위하여 욕중 Al을 낮추어 작업한다.The Al content in the plating bath is added in the range of 0.15-0.20% by weight based on the total Al amount when producing hot-dip galvanized steel sheet, but in the case of alloyed hot-dip galvanized steel sheet, the Al in the bath is lowered to promote alloying of the plating layer.
도금욕내 전 Al량이 낮아지면 Fe 고용한도가 높아져서 하부 드로스(FeZn7, δ상)가 많이 생성되며 이때 생성된 드로스는 각종 롤이나 스트립에 부착하여 강판 표면품질을 열화시킨다.When the total amount of Al in the plating bath is lowered, the Fe solid solution limit is increased to generate a lot of lower dross (FeZn 7 , δ phase), and the generated dross is attached to various rolls or strips to deteriorate the surface quality of the steel sheet.
따라서 표면 외관을 향상시키기 위하여 도금욕내 하부 드로스를 최소화하는 것이 바람직하다. 이와같이 하부 드로스를 최소화시키기 위하여 도금욕내 과포화 Fe량을 줄이는 것이 중요하며 이때 도금욕내 Al량을 상향 조절하여 상부 드로스를 치환시킬 수 있다.Therefore, it is desirable to minimize the lower dross in the plating bath to improve the surface appearance. As such, it is important to reduce the amount of supersaturated Fe in the plating bath in order to minimize the lower dross. At this time, the upper dross may be substituted by adjusting the amount of Al in the plating bath upward.
도금욕 온도가 455-465℃범위에서 유지되면서 전 Al 농도가 0.15%를 초과하면 도금욕내 유효 Al 농도가 0.13% 이상, 고용 Fe 농도는 0.025% 수준이 되며 Fe2Al5의 합금층이 생성되기 시작한다. 이 Fe2Al5층은 치밀한 화합물층으로서 도금후 합금화반응을 지연시키는 역할을 하므로 바람직하지 않다.When the plating bath temperature is maintained in the range of 455-465 ℃ and the total Al concentration exceeds 0.15%, the effective Al concentration in the plating bath is 0.13% or more, the solid solution Fe concentration is 0.025%, and an alloy layer of Fe 2 Al 5 is formed. To start. This Fe 2 Al 5 layer is a dense compound layer, which serves to delay the alloying reaction after plating, which is not preferable.
한편 상기 도금욕 온도 455-465℃ 범위에서 도금욕내 전 Al 농도가 0.12% 이하가 되면 유효 Al 농도가 0.11% 이하가 되어 하부 드로스가 급격히 증가되면서 스트립 표면에 부착하므로 표면 외관이 열화된다.On the other hand, when the total Al concentration in the plating bath temperature ranges from 455-465 ° C. to 0.12% or less, the effective Al concentration is 0.11% or less, and the lower dross rapidly increases and adheres to the strip surface, thereby deteriorating the surface appearance.
또한, 도금욕내 전 Al 농도가 0.13-0.14% 범위에서 전 Fe 농도가 0.05% 이상이 되면 유효 Al 농도의 감소에 따라 하부 드로스가 형성되므로 바람직하지 않다. 따라서, 본 발명에 있어서 도금욕내 전 Al 함량은 0.13-0.14%, 전 Fe 함량은 0.04% 이하로 관리하는 것이 필요하다.In addition, when the total Al concentration in the plating bath is 0.13-0.14% and the total Fe concentration is 0.05% or more, since the lower dross is formed according to the decrease in the effective Al concentration, it is not preferable. Therefore, in the present invention, it is necessary to manage the total Al content in the plating bath to 0.13-0.14%, and the total Fe content to 0.04% or less.
합금화 반응성에 미치는 인자로는 강종, 연속소둔 조건, 도금조건, 합금화 처리조건 등을 들 수 있다. 특히, 도금욕중 알루미늄 농도는 합금화 반응속도, 합금층 구조 및 표면조직에 영향을 미치는 인자로서 스트립 통과 속도와 합금화 길이를 고려하여 조정된다.Factors affecting the alloying reactivity include steel grade, continuous annealing conditions, plating conditions, alloying treatment conditions and the like. In particular, the aluminum concentration in the plating bath is adjusted in consideration of the strip passing speed and the alloying length as factors affecting the alloying reaction rate, the alloy layer structure and the surface structure.
소지철 강종의 영향으로 티타늄(Ti)이 첨가된 극저탄소강은 알루미늄 킬드 저탄소강과는 달리 용융아연 도금시 아연-철 금속간화합물의 계면에 생성하게 된다. 이러한 금속간화합물은 합금화처리시 소지강종내 철의 확산을 조장하여 합금층내 철의 농도가 증가한다. 도금층내 철의 농도가 적정치 이상으로 증가하면 소지철/도금층 계면에서 캐피털 감마(γ)층이 생성됨으로서 가공시 파우더링성 경향이 높으며 따라서 가공성이 열화된다.The ultra-low carbon steel with titanium (Ti) added due to the influence of ferrous steels, unlike the aluminum-kilted low carbon steel, is produced at the interface of zinc-iron intermetallic compound during hot dip galvanizing. These intermetallic compounds promote the diffusion of iron in the steel grade during the alloying process, thereby increasing the iron concentration in the alloy layer. Increasing the iron concentration in the plating layer above an appropriate value generates a capital gamma (γ) layer at the base iron / plating layer interface, so that the powdering property tends to be high during processing, thereby degrading workability.
고가공용강의 합금화처리시 티타늄 첨가 극저탄소강이 많이 사용되고 있으며, 이 경우 480-520℃에서 열처리하면 소지철/도금층 계면에서의 캐피탈 감마(γ)층 생성을 방지하면서 가공성을 확보할 수 있다.Titanium-added ultra-low carbon steel is frequently used during alloying of high-process steel, and in this case, heat treatment at 480-520 ° C. can secure workability while preventing the formation of a capital gamma (γ) layer at the base iron / plated layer interface.
즉, 티타늄-니오븀 복합첨가 극저탄소강의 경우 480℃ 이하에서는 도금층중의 철의 농도가 9% 이하로 되며 도금층 조직이 제타+델타(τ+δ)상으로 구성되어져 프레스 가공시 파우더링성은 양호하나 가압력(Punch Load)이 증가하여 프레스 성형성 불량이 발생되기 쉽고 카치온 전착도장시 폭부풀음 현상이 발생하여 가공성, 내식성이 저하된다.That is, in the case of the ultra-low carbon steel with titanium-niobium composite, the iron concentration in the plating layer is 9% or less at 480 ° C or lower, and the plating layer structure is composed of zeta + delta (τ + δ), so that the powdering property is good during press working. Poor press formability is increased due to the increase in punch load, and swelling phenomenon occurs during the electrodeposition coating.
또한 520℃ 이상에서 열처리하면 도금층내 철의 농도가 12% 이상이 되며, 소지철/도금층 계면에서 가공성이 취약한 캐피탈 감마(γ)상이 나타남으로써 바람직하지 않다.In addition, when the heat treatment at 520 ℃ or more, the iron concentration in the plating layer is 12% or more, it is not preferable because the appearance of the capital gamma (γ) phase is poor workability at the base iron / plating layer interface.
따라서, 본 발명에 있어서, 합금화처리 온도는 티타늄-니오븀 복합첨가 극저탄소강의 경우 480-520℃로 제한하는 것이 바람직하다.Therefore, in the present invention, the alloying temperature is preferably limited to 480-520 ° C in the case of a titanium-niobium compound-added ultra low carbon steel.
이하 실시예를 통하여 본 발명을 보다 구체적으로 설명한다.The present invention will be described in more detail with reference to the following Examples.
[실시예]EXAMPLE
두께 0.8mm인 티타늄-니오븀 복합첨가 극저탄소강(Ti-Nb TFS)의 냉연강판을 소재로 800℃에서 1분간 환원 열처리한 후 하기 표 1과 같은 조건으로 용융도금 및 합금화처리를 행하여 편면 도금부착량이 60-80g/m2범위로 제조한 합금화 용융아연 도금강판의 가공성 및 표면외관을 조사하였다. 이때 가공성은 에릭센(Erichen) 가공 전후의 무게 차이를 비교하여 측정하였다. 또한 표면외관은 상기 합금화 용융아연 도금강판의 길이 200mm 시편을 20mm의 깊이로 가공한후 드로스 발생 유무를 관찰하고 그 결과를 하기 표 1에 나타내었다.After cold-treating a cold-rolled steel sheet of titanium-niobium compound-added ultra low carbon steel (Ti-Nb TFS) having a thickness of 0.8 mm for 1 minute at 800 ° C., the plated amount of one-sided coating was subjected to melt plating and alloying under the conditions shown in Table 1 below. The workability and surface appearance of the alloyed hot-dip galvanized steel sheet prepared in the range of 60-80 g / m 2 were investigated. At this time, the workability was measured by comparing the weight difference before and after the Erichen processing. In addition, the surface appearance was observed after dross generation after processing the 200mm specimen length of the alloyed hot-dip galvanized steel sheet to a depth of 20mm and the results are shown in Table 1 below.
상기 표 1에 나타난 바와 같이 본 발명의 도금부착량 및 합금화 처리 온도 범위를 만족하는 발명재(1-12)의 경우에는 가공성 및 표면외관이 우수한 반면에 본 발명의 범위를 벗어나는 비교재(A-L)의 경우에는 발명재에 비해 가공성 및 표면외관이 열화됨을 알 수 있다.As shown in Table 1, in the case of the inventive material (1-12) satisfying the plating deposition amount and the alloying treatment temperature range of the present invention, the workability and surface appearance were excellent, whereas the comparative material (AL) outside the scope of the present invention was In this case, it can be seen that workability and surface appearance deteriorate compared to the invention material.
[표 1]TABLE 1
* 가공성 : 에릭센(Enichen) 가공 전후 무게 차이에 의한 비교* Workability: Comparison by weight difference before and after Eriken processing
NA☆☆ : 합금화안됨(Not Alloyed)NA ☆☆: Not Alloyed
1) 환원 열처리조건 : 도금욕 인입 시편온도 460℃1) Reduction heat treatment condition: Plating bath lead-in specimen temperature 460 ℃
2) 표면외관 : 팬 드로우 시험(Pan Draw Test)후 도금층 중 드로스 발생 유무조사2) Surface appearance: Investigate the occurrence of dross in the plating layer after the Pan Draw Test.
상술한 바와 같이 본 발명은 합금화 용융아연 도금강판 제조시 도금욕내 Al, Fe 성분조정 및 합금화 처리온도를 조정함으로써 가공성 및 표면외관이 우수한 합금화 용융아연도금강판을 제조할 수 있는 효과가 있다.As described above, the present invention has the effect of manufacturing an alloyed hot-dip galvanized steel sheet having excellent workability and surface appearance by adjusting the Al and Fe components in the plating bath and adjusting the alloying treatment temperature when manufacturing the alloyed hot-dip galvanized steel sheet.
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