KR100696850B1 - A descaling method for low Cr ferritic stainless steel - Google Patents

A descaling method for low Cr ferritic stainless steel Download PDF

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KR100696850B1
KR100696850B1 KR1020050101855A KR20050101855A KR100696850B1 KR 100696850 B1 KR100696850 B1 KR 100696850B1 KR 1020050101855 A KR1020050101855 A KR 1020050101855A KR 20050101855 A KR20050101855 A KR 20050101855A KR 100696850 B1 KR100696850 B1 KR 100696850B1
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stainless steel
pickling
ferritic stainless
electrolytic cell
steel sheet
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KR1020050101855A
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Korean (ko)
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원태연
이용헌
김광태
하헌재
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주식회사 포스코
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    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25F—PROCESSES FOR THE ELECTROLYTIC REMOVAL OF MATERIALS FROM OBJECTS; APPARATUS THEREFOR
    • C25F1/00—Electrolytic cleaning, degreasing, pickling or descaling
    • C25F1/02—Pickling; Descaling
    • C25F1/04—Pickling; Descaling in solution
    • C25F1/06—Iron or steel
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21B—ROLLING OF METAL
    • B21B45/00—Devices for surface or other treatment of work, specially combined with or arranged in, or specially adapted for use in connection with, metal-rolling mills
    • B21B45/04—Devices for surface or other treatment of work, specially combined with or arranged in, or specially adapted for use in connection with, metal-rolling mills for de-scaling, e.g. by brushing
    • 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
    • C23G—CLEANING OR DE-GREASING OF METALLIC MATERIAL BY CHEMICAL METHODS OTHER THAN ELECTROLYSIS
    • C23G1/00—Cleaning or pickling metallic material with solutions or molten salts
    • C23G1/02—Cleaning or pickling metallic material with solutions or molten salts with acid solutions
    • C23G1/08—Iron or steel
    • C23G1/085—Iron or steel solutions containing HNO3
    • 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
    • C23G—CLEANING OR DE-GREASING OF METALLIC MATERIAL BY CHEMICAL METHODS OTHER THAN ELECTROLYSIS
    • C23G1/00—Cleaning or pickling metallic material with solutions or molten salts
    • C23G1/02—Cleaning or pickling metallic material with solutions or molten salts with acid solutions
    • C23G1/08—Iron or steel
    • C23G1/086—Iron or steel solutions containing HF

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  • Engineering & Computer Science (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Mechanical Engineering (AREA)
  • General Chemical & Material Sciences (AREA)
  • Electrochemistry (AREA)
  • Cleaning And De-Greasing Of Metallic Materials By Chemical Methods (AREA)

Abstract

A method for pickling a low Cr ferritic stainless steel at high speed is provided to improve surface glossiness of a product through a uniform pickling effect obtained by performing a pickling operation within a short time on the annealed stainless steel sheet after performing hot rolling or cold rolling and annealing on a stainless steel sheet. In a method for pickling a ferritic stainless steel containing 11 to 12 wt.% of Cr to remove scale formed on the annealed stainless steel sheet after performing hot or cold rolling and annealing on a stainless steel sheet, the method comprises: passing the stainless steel sheet through a neutral salt electrolytic cell and a sulfuric acid electrolytic cell to which an electric current of 0.018 to 0.05 A/cm^2 is applied; performing nitric acid electrolysis of the ferritic stainless steel passing through the neutral salt electrolytic cell and the sulfuric acid electrolytic cell using an electric current of 0.024 to 0.03 A/cm^2; and dipping the nitric acid electrolysis performed ferritic stainless steel into a mixed acid of nitric acid and hydrofluoric acid.

Description

저크롬 페라이트계 스테인레스강의 고속산세방법{A descaling method for low Cr ferritic stainless steel}A high descaling method for low Cr ferritic stainless steel

도 1은 본 발명의 일 실시예에 관한 409L 강종의 소둔 스케일 특성을 도시한 도면이다.1 is a view showing an annealing scale characteristics of 409L steel sheet according to an embodiment of the present invention.

본 발명은 저크롬계 페라이트계 스테인레스강의 산세방법에 관한 것으로, 더욱 상세하게는 열간압연 또는 냉간압연 후에 소둔 열처리된 스테인레스강판에 대하여 단시간내에 산세처리를 할 경우의 균일한 산세효과를 통해 제품의 표면광택도 향상을 도모할 수 있는 스테인레스 냉연강판용 산세방법에 관한 것이다.The present invention relates to a method for pickling low chromium-based ferritic stainless steel, and more particularly, to a surface of a product through a uniform pickling effect when the pickling treatment is performed in a short time on a hot-rolled or cold-rolled annealing stainless steel sheet. The present invention relates to a pickling method for a stainless cold rolled steel sheet capable of improving glossiness.

일반적으로, 11 wt% 이상의 크롬(Cr)을 함유하는 슬라브는 열간압연 또는 냉간압연 후 소둔 열처리되고, 이 후에 산세공정을 통해서 표면 스케일이 제거되어 매끄러운 표면상태를 갖는 스테인레스 강판으로 제조된다.In general, slabs containing 11 wt% or more of chromium (Cr) are annealed after hot rolling or cold rolling, and after that, the surface scale is removed through a pickling process to produce a stainless steel sheet having a smooth surface state.

종래 산세공정은 황산 전해공정과 질산 및 불산의 혼합공정 그리고 질산공 정으로 이루어지며, 스테인레스 강판은 이들 3단계 공정을 통해 산세처리되거나 또는 황산 베이스(Base)에 Na2SiF6와 NaNO3를 첨가한 전해산세용액에서 산세처리된다. 이외에도 스테인레스강판을 산세처리하기 위해 용융염에서 전처리 한 후 질산 전해나 혼산조를 통과시키기도 하는 등 다양한 산세기술이 제공되고 있다.Conventional pickling process consists of electrolytic sulfuric acid process, mixing process of nitric acid and hydrofluoric acid, and nitric acid process. Stainless steel plate is pickled through these three steps or Na 2 SiF 6 and NaNO 3 are added to sulfuric acid base. Pickled in an electrolytic pickling solution. In addition, a variety of pickling techniques are provided, such as pretreatment in molten salt for pickling of stainless steel plates and then passing through nitric acid electrolysis or mixed acid baths.

한편, 스테인레스강은 11 wt% 이상의 Cr을 함유하므로 압연공정 또는 소둔 열처리 동안에 스테인레스강판의 표면에는 Fe 산화물 뿐만 아니라 치밀한 조직의 크롬산화 피막층이 형성된다. 이러한 크롬산화 피막층은 산세공정동안 전처리과정이나 산세용액에 의해 제거되게 된다. 그러나, 산세에 의한 크롬산화 피막층의 제거가 균일하지 못하거나, 완전 산세가 되지 않을 경우 제품의 가치가 떨어지게 된다. 따라서, 표면광택도가 향상된 스테인레스 제품을 생산할 수 있는 효과적이면서도 우수한 산세효과를 나타낼 수 있는 산세방법이 요구된다.On the other hand, since stainless steel contains 11 wt% or more of Cr, not only Fe oxide but also a dense chromium oxide coating layer is formed on the surface of the stainless steel sheet during the rolling process or annealing heat treatment. The chromium oxide film layer is removed by a pretreatment or pickling solution during the pickling process. However, if the removal of the chromium oxide coating layer by pickling is not uniform or if it is not completely pickled, the value of the product will be reduced. Therefore, there is a need for a pickling method that can produce an effective and excellent pickling effect to produce a stainless product with improved surface gloss.

본 발명은 상기의 문제점을 해결하기 위하여 제안된 것으로써, 스테인레스강 슬라브를 통상의 열간압연 과정에서 행하는 압하율로 압연을 실시하고 소둔산세 후 Z-mill 냉간압연기를 이용하여 냉간압연한 후 산화성 분위기에서 소둔열처리된 냉연소둔 스테인레스강판을 산세처리하였을 때 강판의 표면광택도가 압연방향에서 광원입사각 60도로 측정하였을 때 150 이상을 나타낼 수 있도록 균일하면서도 우수한 산세효과를 나타낼 수 있는 스테인레스 냉연강판용 산세방법을 제공하는 데 그 목 적이 있다. The present invention has been proposed in order to solve the above problems, the stainless steel slab is subjected to rolling at a rolling rate performed in a normal hot rolling process, and after annealing and cold rolling using a Z-mill cold rolling machine, an oxidizing atmosphere. When pickling the cold-annealed annealed stainless steel sheet subjected to annealing at Its purpose is to provide.

본 발명은 상기 목적을 달성하기 위하여, 열간압연 또는 냉간압연 후 소둔 열처리에 의해 표면에 형성된 스케일을 제거하기 위한 11~12wt% Cr을 함유하는 페라이트계 스테인레스강의 산세방법에 있어서, 상기 강종은 0.018~0.05A/cm2의 전류가 인가된 중성염 전해조와 황산 전해조를 연속하여 통과한 후, 0.024~0.03 A/cm2가 인가된 질산 전해를 실시한 후, 질산과 불산의 혼산 침지를 추가하는 것을 특징으로 한다. In the present invention, in order to achieve the above object, in the pickling method of ferritic stainless steel containing 11 ~ 12wt% Cr for removing the scale formed on the surface by annealing heat treatment after hot rolling or cold rolling, the steel grade is 0.018 ~ 0.05A / cm 2, after current is applied to a series of the neutral salt electrolytic bath and the sulfuric acid electrolytic bath passage of, after performing the 0.024 ~ 0.03 a / cm 2 is delivered with the nitric acid, characterized by adding a mixed acid of nitric acid and hydrofluoric acid dipping It is done.

또한, 본 발명에서 상기 산세시의 용액의 온도는 50~90℃인 것이 바람직하다. 또한, 본 발명에서 혼산 침지시의 질산농도는 100 g/l, 불산농도 3~17 g/l를 사용하고, 온도는 40~70℃로 한다. In the present invention, the temperature of the solution at the time of pickling is preferably 50 ~ 90 ℃. In addition, in this invention, nitric acid concentration at the time of mixed acid immersion uses 100 g / l, hydrofluoric acid concentration 3-17 g / l, and makes temperature 40-70 degreeC.

또한, 본 발명에서 전해조내의 금속이온농도는 45mg/L 이하로 유지한다. In addition, in the present invention, the metal ion concentration in the electrolytic cell is maintained at 45 mg / L or less.

이하 본 발명을 도면을 참조하여 더욱 상세히 설명하기로 한다. Hereinafter, the present invention will be described in more detail with reference to the drawings.

도 1은 본 발명의 일 실시예에 관한 409L 강종의 소둔 스케일 특성을 도시한 도면이다. 본 발명에서는 먼저, 스테인레스강 슬라브를 통상의 열간압연 과정에서 행하는 압하율로 압연을 실시하고 소둔산세 후 Z-mill 냉간압연기를 이용하여 냉간압연한 후 산화성 분위기에서 소둔열처리된 냉연소둔 스테인레스강판을 산세처리하였을 때 중성염 전해, 황산 전해, 질산 전해, 그리고 최종적으로 혼산을 사용하여 산세를 실시한다. 또한, 황산 전해조를 사용시 중성염 전해조의 일부는 황산을 채워 사용한다 1 is a view showing an annealing scale characteristics of 409L steel sheet according to an embodiment of the present invention. In the present invention, first, the stainless steel slab is rolled at a reduction ratio performed in a normal hot rolling process, followed by annealing, followed by cold rolling using a Z-mill cold rolling machine, followed by pickling of the cold-annealed stainless steel sheet subjected to annealing heat treatment in an oxidizing atmosphere. When treated, pickling is carried out using neutral salt electrolysis, sulfuric acid electrolysis, nitric acid electrolysis, and finally mixed acid. In addition, when using sulfuric acid electrolyzer, part of neutral salt electrolyzer is filled with sulfuric acid.

이는 도 1에서 알 수 있는 바와 같이, 409L강종에서는 철부유(Fe-rich) 스케일이 형성되고, 스케일/모재 계면에 다량의 SiO2 스케일이 형성되며, 철부유 스케일과 SiO2 스케일은 중성염 전해산세를 어렵게 하는 특징이 있다.As can be seen in Figure 1, in the 409L steel, iron-rich (Fe-rich) scale is formed, a large amount of SiO 2 scale is formed on the scale / base material interface, iron-rich scale and SiO 2 scale is neutral salt electrolytic There are features that make pickling difficult.

특히 산화성분위기에서 열처리시 스테인레스 강종별 크롬함량과 소둔온도가 상이하여 산화스케일의 조성과 두께 및 표면색상이 다르게 된다.In particular, the chromium content and annealing temperature for each stainless steel are different during heat treatment in the oxidizing atmosphere, so the composition, thickness and surface color of the oxidizing scale are different.

이들 강종계에서 산화스케일을 제거할 경우 여러 경로의 산세공정이 있는데 각 공정별 특징을 정리하면 다음과 같다.When the scale is removed from these steel systems, there are several pickling processes. The characteristics of each process are as follows.

11~12wt% 크롬 함유 페라이트계 스테인레스 냉연강판을 산화성분위기에서 열처리하면 주로 철부유 스케일이 형성되며 스케일 계면과 모재사이에 다량의 SiO2 형성되고 열처리 온도가 증가하고 시간이 증가하면서 스케일 두께가 증가된다.Heat treatment of 11 ~ 12wt% chromium-containing ferritic stainless cold rolled steel sheet in the oxidizing atmosphere mainly forms iron-rich scale, and a large amount of SiO 2 is formed between the scale interface and the base metal, and the scale thickness increases with increasing heat treatment temperature and time. .

이들 강종계에서 산화스케일을 제거할 경우 여러 경로의 산세공정이 있는데 각 공정별 특징을 정리하면 다음과 같다.When the scale is removed from these steel systems, there are several pickling processes. The characteristics of each process are as follows.

먼저, 상기 11~12wt% 크롬 함유 페라이트계 스테인레스 냉연강판을 중성염 전해조를 통과시킨다. 그러나, 황산나트륨을 함유하고 있는 중성염수용액에서 일정전류를 가하여 전해산세를 할 경우 철부유 스케일이 형성된 11~12wt% 크롬 함유 페라이트계 스테인레스 냉연강판의 경우 양극반응에 의해 크롬 산화물의 용해반응이 쉽게 일어나기 어려운 점이 있다. First, the 11-12 wt% chromium-containing ferritic stainless cold rolled steel sheet is passed through a neutral salt electrolytic cell. However, in the case of electrolytic pickling with a constant current in a neutral saline solution containing sodium sulfate, 11-12 wt% chromium-containing ferritic stainless steel cold rolled steel sheet having an iron-rich scale easily dissolves chromium oxide by anodization. There is a difficulty.

따라서 후속공정으로 황산 전해과정을 거치게 된다. 이때 부가적인 황산 전해과정을 거치게 되나, Fe산화물이 중성염수용액 및 황산수용액에서 전기화학반응에 의해 용해되지 않기 때문에 산화스케일 중의 Fe산화물을 제거하기 위해 후속공정으로 질산 전해과정을 거치게 된다. Therefore, the sulfuric acid electrolysis process is followed. At this time, an additional sulfuric acid electrolysis process is performed, but since the Fe oxide is not dissolved in the electrolytic reaction in the neutral saline solution and the sulfuric acid solution, the nitric acid electrolysis process is performed as a subsequent process to remove the Fe oxide in the oxidized scale.

아울러 스케일 중에 존재하고 있는 Si산화물은 중성염 전해, 황산 전해 및 질산 전해로도 불가능하기 때문에 질산과 불산으로 구성되어 있는 혼산조에서 침적과정을 통해 단시간내에 완전한 산화스케일 제거가 가능하다.In addition, since the Si oxide present in the scale is impossible to neutral salt electrolysis, sulfuric acid electrolysis, and nitric acid electrolysis, it is possible to completely remove the oxidative scale in a short time through the deposition process in the mixed acid tank composed of nitric acid and hydrofluoric acid.

이하 본 발명의 바람직한 산세조건에 대하여 상세히 설명하기로 한다.Hereinafter, the pickling conditions of the present invention will be described in detail.

본 발명에서는 열간압연 또는 냉간압연 후 소둔 열처리에 의해서 스테인레스 냉연강판의 표면에 형성된 표면 스케일을 제거하기 위한 산세방법을 공정별로 구분하여 설명한다. In the present invention, the pickling method for removing the surface scale formed on the surface of the stainless cold rolled steel sheet by annealing heat treatment after hot rolling or cold rolling will be described separately by process.

먼저, 본 발명은 중성염 전해 - 황산 전해 - 질산 전해 - 혼산 침지의 단계로 구성된다. 먼저, 상기 중성염 전해의 전해조는 셀(cell)당 6m 길이인 14개의 ㅅ셀로 구성되나, 황산 전해조를 이용하는 본 발명의 경우 상기 14개의 셀중 4개의 셀을 황산 전해조로 구성할 수 있다. 또한, 본 발명에 관한 저크롬 페라이트계 스테인레스강은 반드시 황산 전해조를 통과시키는데, 이때 스케일의 일부를 잔존시켜 통과시키게 된다. First, the present invention consists of the steps of neutral salt electrolysis-sulfuric acid electrolysis-nitric acid electrolysis-mixed acid immersion. First, the electrolytic cell of the neutral salt electrolysis is composed of 14 cells which are 6 m long per cell, but in the case of the present invention using a sulfuric acid electrolytic cell, four cells of the 14 cells may be configured as a sulfuric acid electrolytic cell. In addition, the low chromium ferritic stainless steel according to the present invention must pass through the sulfuric acid electrolytic cell, at which time a portion of the scale is left to pass.

또한, 상기 중성염 전해조 및 황산 전해조의 셀 당 전류가 최대 양극기준으로 0.066A/cm2로 구성된 전해조에서 중성염 전해시 전류는 0.027~0.05 A/cm2를 인가하며, 황산 전해조에서의 전류밀도는 0.018~0.05A/cm2를 인가하게 된다. 단, 본 발명에 관한 저크롬 페라이트계 스테인레스강은 반드시 황산 전해조를 통과하게 되므로, 상기 중성염 전해시의 전류를 0.018~0.05A/cm2 로 낮추는 것이 가능하다. In addition, in the electrolytic cell in which the current per cell of the neutral salt electrolytic cell and sulfuric acid electrolytic cell is 0.066 A / cm 2 based on the maximum anode, the neutral salt current is applied at 0.027 to 0.05 A / cm 2 , and the current density in the sulfuric acid electrolytic cell is applied. Will apply 0.018 ~ 0.05A / cm 2 . However, since the low chromium ferritic stainless steel according to the present invention necessarily passes through the sulfuric acid electrolytic cell, it is possible to lower the current during the neutral salt electrolysis to 0.018 to 0.05 A / cm 2 .

또한, 후속공정으로서의 질산 전해조는 4개의 셀로 구성되며 최대 0.033 A/cm2 로 구성된 전해조에서 0.024~0.03 A/cm2 를 인가한다. 본 발명에서의 전해산세시 용액의 온도는 바람직하게는 50~90℃로 한다. 이는 온도가 50도보다 낮을 경우 반응속도가 저하되고, 90도를 넘을 경우 과산세 및 질산 증기발생에 따른 공해문제가 있기 때문이다. 특히, 혼산조는 최대 54m로 구성된 전해조에서 질산농도 100 g/l, 불산농도 3~17 g/l 를 사용한다. 용액의 온도는 40~70℃로 한다. 이는 온도가 40℃ 미만일 경우 반응속도가 저하되고, 70℃ 초과일 경우 과산세 및 질산 증기의 발생과 공해문제가 있기 때문이다. 전해조내의 금속이온농도는 45mg/L이하로 관리하여 침전물 과다로 인한 표면특성 저하등의 산세능 저하를 방지한다. In addition, the nitric acid electrolyzer as a subsequent step is composed of four cells, and 0.024 to 0.03 A / cm 2 is applied in an electrolytic cell composed of a maximum of 0.033 A / cm 2 . The temperature of the electrolytic pickling solution in the present invention is preferably 50 to 90 ° C. This is because if the temperature is lower than 50 degrees, the reaction rate is lowered, and if the temperature is higher than 90 degrees, there is a pollution problem due to the generation of superacid and nitric acid vapor. In particular, the mixed acid tank uses nitric acid concentration of 100 g / l and hydrofluoric acid concentration of 3 to 17 g / l in an electrolytic cell composed of up to 54 m. The temperature of the solution shall be 40-70 degreeC. This is because the reaction rate is lowered when the temperature is less than 40 ℃, and there is a problem with the generation of super-acid tax and nitrate vapor when the temperature is above 70 ℃. The metal ion concentration in the electrolytic cell is managed at 45mg / L or less to prevent the deterioration of pickling ability such as surface property deterioration due to excessive sediment.

본 발명에서의 조성물의 상하한을 정한 사유는 먼저, 중성염(Na2SO4) 수용액에서 전해산세시 우수한 광택도(150 이상)를 얻기 위한 전류밀도는 0.027 ~ 0.05 A/cm2 로 한정한다. 또한, 황산(H2SO4) 수용액에서 전해산세시 우수한 광택도(150 이상)를 얻기 위한 전류밀도는 0.018 ~ 0.05 A/cm2 로 한정한다. 또한, 우수한 광택도(150 이상)를 얻기 위한 혼산(질산+불산) 용액내의 불산농도는 3 ~ 17 g/l 로 한정한다. 상기와 같은 전류밀도의 최적 범위는 후술하는 실시예를 보면 알 수 있다.The reason for determining the upper and lower limits of the composition of the present invention is first, the current density for obtaining excellent glossiness (150 or more) during electrolytic pickling in a neutral salt (Na 2 SO 4 ) aqueous solution is limited to 0.027 ~ 0.05 A / cm 2 . In addition, the current density for obtaining excellent glossiness (150 or more) during electrolytic pickling in sulfuric acid (H 2 SO 4 ) aqueous solution is limited to 0.018 ~ 0.05 A / cm 2 . In addition, the hydrofluoric acid concentration in the mixed acid (nitric acid + hydrofluoric acid) solution for obtaining excellent glossiness (150 or more) is limited to 3 to 17 g / l. The optimum range of the current density as described above can be seen from the following examples.

Nb첨가 안정화 페라이트계 스테인레스 냉연강판을 산화성분위기에서 열처리하면 Cr과 Fe량이 유사한 스케일이 형성되며 스케일 계면과 모재사이에 다량의 SiO2 형성되고 열처리 온도가 증가하고 시간이 증가하면서 스케일 두께가 증가된다. 이들 강종계에서 산화스케일을 제거하는 산세공정은 11~12wt% Cr 함유 페라이트계 스테인레스 냉연소둔강판의 경우와 유사하다. The scale thickness is increased, while Nb was added to stabilize the ferritic stainless steel when annealing the cold-rolled steel sheet in an oxidizing atmosphere, and a similar scaling the amount of Cr and Fe is formed in a large amount of SiO 2 between the scale surface and the base material increases the heat treatment temperature and increase the time. The pickling process to remove the oxidative scale from these steel grades is similar to that of 11-12 wt% Cr-containing ferritic stainless steel.

이하 본 발명의 실시예을 살펴본다. 본 실시예에서는 11~12wt% Cr을 함유하는 409L강종을 대상으로 실시하였다.Hereinafter, an embodiment of the present invention will be described. In this example, 409L steel grades containing 11-12 wt% Cr were used.

(실시예)(Example)

409L (130mpm) 409L (130mpm)

　 중성염 전해Neutral salt electrolysis 황산 전해Sulfuric acid electrolysis 질산 전해Nitric acid electrolysis 혼산처리Mixed acid treatment 광택도 (L : 60˚)Glossiness (L: 60˚) 판정　Judgment 　 전류밀도 (A/㎠)Current density (A / ㎠) 전류밀도(A/㎠)Current density (A / ㎠) 전류밀도(A/㎠)Current density (A / ㎠) HF (g/ℓ)HF (g / ℓ) 1One 0.0150.015 0.030 0.030 0.0200.020 20.0 20.0 -- XX 22 0.027 0.027 0.0150.015 0.024 0.024 2.0 2.0 150 150 △△ 33 0.027 0.027 0.018 0.018 0.024 0.024 15.0 15.0 163 163 ○○ 44 0.0180.018 0.042 0.042 0.024 0.024 3.0 3.0 158 158 ○○ 55 0.027 0.027 0.042 0.042 0.024 0.024 15.0 15.0 179 179 ○○ 66 0.036 0.036 0.010 0.010 0.024 0.024 10.0 10.0 157 157 ○○ 77 0.036 0.036 0.030 0.030 0.024 0.024 1.6 1.6 171 171 ○○ 88 0.036 0.036 0.030 0.030 0.024 0.024 10.0 10.0 172 172 ○○ 99 0.036 0.036 0.030 0.030 0.0300.030 16.0 16.0 191 191 ◎◎ 1010 0.036 0.036 0.050 0.050 0.024 0.024 10.0 10.0 169 169 ○○ 1111 0.045 0.045 0.018 0.018 0.024 0.024 5.0 5.0 159 159 ○○ 1212 0.045 0.045 0.018 0.018 0.0300.030 15.0 15.0 198 198 ◎◎ 1313 0.045 0.045 0.042 0.042 0.024 0.024 5.0 5.0 186 186 ◎◎ 1414 0.045 0.045 0.042 0.042 0.030 0.030 17.0 17.0 182 182 ◎◎ 1515 0.051 0.051 0.030 0.030 0.024 0.024 10.0 10.0 192 192 ◎◎

◎ : ◎: 광택우수Excellent gloss , ○ : , ○: 광택양호Gloss , △ : , △: 광택보통Polished , X : 광택불량, X: poor gloss

중성염 전해: Na2SO4 150 g/ℓ, 70℃, A/C/A=6/6/6Neutral salt electrolysis: Na 2 SO 4 150 g / l, 70 ° C, A / C / A = 6/6/6

황산 전해 : H2SO4 150 g/ℓ, 60℃, A/C/A=2/2/2 Sulfuric acid electrolysis: H 2 SO 4 150 g / ℓ, 60 ℃, A / C / A = 2/2/2

질산 전해 : HNO3 100 g/ℓ, 50℃, A/C/A=2/2/2Nitric acid electrolysis: HNO 3 100 g / ℓ, 50 ℃, A / C / A = 2/2/2

혼산처리 : 60℃, 25초, HNO3 90 g/ℓMixed acid treatment: 60 ℃, 25 seconds, HNO 3 90 g / ℓ

(여기서, A:양극반응시간, C:음극반응시간)Where A is the positive reaction time and C is the negative reaction time.

표 1은 409L 냉연소둔강판을 산세한 실험결과를 나타낸다.Table 1 shows the results of pickling 409L cold rolled annealing steel sheet.

상기 표 1에서 알 수 있는 바와 같이, 본 발명에 의한 최적의 전류밀도를 인가한 실시예 9, 12, 13, 14, 15의 경우 광택도가 현저히 우수하게 나타나는 것을 알 수 있다. 한편 실시예 1의 경우 중성염 전해조의 전류밀도가 낮고, 실시예 2의 경우 황산 전해조의 전류밀도가 낮으므로 광택도가 불량으로 나타나는 것을 알 수 있다. 따라서, 본 발명의 최적 전류밀도의 임계범위는 중성염 전해조와 황산 전해조의 경우 0.018~0.05A/cm2하는 것이 우수한 것을 알 수 있다. 또한, 질산 전해의 전류밀도는 0.024~0.03 A/cm2 최적의 범위로 나타났다. 또한, 혼산 침지시의 불산 농도는 3~17 g/l이 바람직한 것을 알 수 있다.As can be seen in Table 1, it can be seen that in the case of Examples 9, 12, 13, 14, and 15 to which the optimum current density according to the present invention is applied, the glossiness is remarkably excellent. On the other hand, since the current density of the neutral salt electrolytic cell is low in Example 1, and the current density of the sulfuric acid electrolytic cell is low in Example 2, it can be seen that the glossiness is poor. Therefore, it can be seen that the critical range of the optimum current density of the present invention is 0.018 to 0.05 A / cm 2 in the case of the neutral salt electrolyzer and the sulfuric acid electrolyzer. In addition, the current density of nitric acid electrolysis was found to be 0.024 to 0.03 A / cm 2 optimum range. In addition, it is understood that the hydrofluoric acid concentration at the time of mixed acid immersion is preferably 3 to 17 g / l.

상술한 바와 같이, 본 발명에 따르면, 스테인레스 냉연소둔강판을 단시간에 산세시킴과 아울러 표면광택도를 향상시킬 수 있는 효과가 있다.As described above, according to the present invention, the stainless cold rolled annealing steel sheet is pickled in a short time, and the surface glossiness can be improved.

Claims (4)

열간압연 또는 냉간압연 후 소둔 열처리에 의해 표면에 형성된 스케일을 제거하기 위한 11~12wt% Cr을 함유하는 페라이트계 스테인레스강의 산세방법에 있어서, 상기 강종은 0.018~0.05A/cm2의 전류가 인가된 중성염 전해조와 황산 전해조를 연속하여 통과한 후, 0.024~0.03 A/cm2가 인가된 질산 전해를 실시한 후, 질산과 불산의 혼산 침지를 추가하는 것을 특징으로 하는 페라이트계 스테인레스강의 산세방법.In the method of pickling ferritic stainless steel containing 11-12 wt% Cr to remove scale formed on the surface by annealing heat treatment after hot rolling or cold rolling, the steel grade is applied with a current of 0.018 ~ 0.05A / cm 2 . A method of pickling ferritic stainless steels, characterized by adding a mixture of nitric acid and hydrofluoric acid after performing nitric acid electrolysis to which 0.024 to 0.03 A / cm 2 is applied after continuously passing through a neutral salt electrolytic cell and a sulfuric acid electrolytic cell. 제1항에 있어서,The method of claim 1, 상기 산세시의 용액의 온도는 50~90℃인 것을 특징으로 하는 페라이트계 스테인레스강의 산세방법.The pickling method of the ferritic stainless steel, characterized in that the temperature of the solution at the time of pickling is 50 ~ 90 ℃. 제1항에 있어서,The method of claim 1, 상기 혼산 침지시의 질산농도는 100 g/l, 불산농도 3~17 g/l를 사용하고, 온도는 40~70℃인 것을 특징으로 하는 페라이트계 스테인레스강의 산세방법.The nitric acid concentration during the mixed acid immersion is 100 g / l, hydrofluoric acid concentration 3 ~ 17 g / l, the temperature is 40 ~ 70 ℃ Pickling method of ferritic stainless steel, characterized in that. 제1항 내지 제3항중 어느 한 항에 있어서,The method according to any one of claims 1 to 3, 전해조내의 금속이온농도는 45mg/L 이하인 것을 특징으로 하는 페라이트계 스테인레스강의 산세방법.Pickling method of ferritic stainless steel, characterized in that the metal ion concentration in the electrolytic cell is 45mg / L or less.
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KR101073186B1 (en) * 2008-12-23 2011-10-12 주식회사 포스코 Method for pickling low chrome ferritic stainless steel
KR101073242B1 (en) * 2008-12-23 2011-10-12 주식회사 포스코 Method for pickling high chrome ferritic stainless steel
KR101073279B1 (en) * 2008-12-23 2011-10-12 주식회사 포스코 Method for pickling molybdenum added ferritic stainless steel
KR101290421B1 (en) 2009-08-21 2013-07-26 주식회사 포스코 The annealing-pickling method for cold rolled stainless steel
EP2660364A2 (en) * 2010-12-28 2013-11-06 Posco Eco-friendly high-speed pickling process for producing a low-chrome ferrite-based cold-rolled stainless steel sheet having superior surface quality
KR101356830B1 (en) * 2011-11-21 2014-01-28 주식회사 포스코 Continuous manufacturing method of ferritic stainless steel
KR101403064B1 (en) * 2010-12-28 2014-06-02 주식회사 포스코 Process for descaling a ferrite stainless steel strip using nitric acid free solutions
CN113528765A (en) * 2021-06-18 2021-10-22 鞍钢联众(广州)不锈钢有限公司 Method for improving surface wrinkling defect of titanium-containing ferrite stainless steel

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JPH0827600A (en) * 1994-07-14 1996-01-30 Nisshin Steel Co Ltd Descaling method and device for stainless steel strip

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Cited By (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR101073186B1 (en) * 2008-12-23 2011-10-12 주식회사 포스코 Method for pickling low chrome ferritic stainless steel
KR101073242B1 (en) * 2008-12-23 2011-10-12 주식회사 포스코 Method for pickling high chrome ferritic stainless steel
KR101073279B1 (en) * 2008-12-23 2011-10-12 주식회사 포스코 Method for pickling molybdenum added ferritic stainless steel
KR101290421B1 (en) 2009-08-21 2013-07-26 주식회사 포스코 The annealing-pickling method for cold rolled stainless steel
EP2660364A2 (en) * 2010-12-28 2013-11-06 Posco Eco-friendly high-speed pickling process for producing a low-chrome ferrite-based cold-rolled stainless steel sheet having superior surface quality
CN103403230A (en) * 2010-12-28 2013-11-20 Posco公司 Eco-friendly high-speed pickling process for producing a low-chrome ferrite-based cold-rolled stainless steel sheet having superior surface quality
KR101403064B1 (en) * 2010-12-28 2014-06-02 주식회사 포스코 Process for descaling a ferrite stainless steel strip using nitric acid free solutions
EP2660364A4 (en) * 2010-12-28 2014-08-13 Posco Eco-friendly high-speed pickling process for producing a low-chrome ferrite-based cold-rolled stainless steel sheet having superior surface quality
KR101356830B1 (en) * 2011-11-21 2014-01-28 주식회사 포스코 Continuous manufacturing method of ferritic stainless steel
CN113528765A (en) * 2021-06-18 2021-10-22 鞍钢联众(广州)不锈钢有限公司 Method for improving surface wrinkling defect of titanium-containing ferrite stainless steel

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