EP0359736A1 - Procédé pour le décapage d'acier spécial par voie électrolytique - Google Patents

Procédé pour le décapage d'acier spécial par voie électrolytique Download PDF

Info

Publication number
EP0359736A1
EP0359736A1 EP89890225A EP89890225A EP0359736A1 EP 0359736 A1 EP0359736 A1 EP 0359736A1 EP 89890225 A EP89890225 A EP 89890225A EP 89890225 A EP89890225 A EP 89890225A EP 0359736 A1 EP0359736 A1 EP 0359736A1
Authority
EP
European Patent Office
Prior art keywords
solution
stainless steel
nano3
naf
aqueous
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Granted
Application number
EP89890225A
Other languages
German (de)
English (en)
Other versions
EP0359736B1 (fr
Inventor
Gerald Dipl.-Ing. Dr. Tech. Maresch
Ulrich Krupicka
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Andritz AG
Original Assignee
Andritz AG
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Andritz AG filed Critical Andritz AG
Publication of EP0359736A1 publication Critical patent/EP0359736A1/fr
Application granted granted Critical
Publication of EP0359736B1 publication Critical patent/EP0359736B1/fr
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

Links

Classifications

    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
    • C25D1/00—Electroforming
    • C25D1/04—Wires; Strips; Foils
    • 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

Definitions

  • the invention relates to a method for the electrolytic pickling of stainless steel strip, in particular stainless steel hot strip, in which the stainless steel hot strip is initially anodically and cathodically pickled in an aqueous neutral solution of Na2SO4.
  • AT-PS 252 685 and AT-PS 240 674 describe two-stage electrolytic pickling processes, the first pickling bath being an aqueous solution of a neutral alkali salt of a mineral acid, preferably sodium sulfate. This is followed by electrolytic pickling in aqueous solutions of mineral acids, examples of which are sulfuric, nitric, hydrochloric or mixed acids. In all of the above-mentioned processes, however, it has not or only insufficiently been possible to effectively prevent the formation of toxic vapors, including nitrous gases.
  • the object of the present invention is to provide a method for electrolytic pickling of stainless steel strips, in which the formation of nitrous gases is completely avoided in the aftertreatment, which furthermore with a low cost and Workload works and delivers a scale-free, bright shiny stainless steel band.
  • Another feature of the method according to the invention is that the concentration of NaNO3 between 100 and 400 g / l, preferably 200 to 300 g / l and the concentration of NaF between 10 and 100 g / l, preferably between 40 and 60 g / l is.
  • the temperature in the solution of NaNO3 and NaF is between 20 and 90 ° C, preferably between 60 and 80 ° C.
  • the anodic and cathodic current density during electrolytic pickling in the solution of NaNO3 and NaF is between 1 and 50 A / dm2, preferably between 10 and 30 A / dm2.
  • the scaled stainless steel strip After the scaled stainless steel strip has been alternately anodically and cathodically pickled in an aqueous solution of Na2SO4, it is rinsed and brushed with plastic brushes. Thereupon it is alternately anodically and cathodically pickled to remove the remaining adhering scale in an aqueous neutral salt solution which contains the same anions as the conventional nitric-hydrofluoric acid mixture.
  • a solution of NaNO3 and NaF is preferably prepared for this purpose.
  • the neutral salt solution is generally prepared in water by adding the respective nitrates or fluorides in the desired amount.
  • other manufacturing methods are also possible, especially in the course of small-scale test facilities, where e.g. a neutralization of HNO3 / HF mixed acid with alkali can be done.
  • Economic considerations lead to the use of sodium salts, since these are the cheapest in terms of price, but the use of nitrates and fluorides with other cations, such as potassium, is just as possible.
  • the electrolytic pickling with NaNO3 and NaF prevents the formation of nitrous gases, since the stainless steel strip is not pickled in acid, but the acid is only produced where it is needed by electrolysis.
  • Another advantage of this method according to the invention is that the dissolved scale does not dissolve as a salt and thus consumes acid, but instead precipitates out as a hydroxide.
  • This metal hydroxide sludge formed during pickling is separated from the solution by mechanical methods such as filters, thickeners or centrifuges. This not only reduces the consumption of chemicals, it also creates easily depositable metal hydroxides.
  • a stainless steel hot strip of quality AISI 304 was irradiated in a combined annealing and pickling line before pickling in order to partially remove the scale on the surface and then electrolytically in an aqueous Na2SO, solution, a concentration of 150 g / l with 10 A / dm2 alternately anodically and cathodically pickled, keeping the temperature in the range between 60 and 80 ° C.
  • the stainless steel strip was first pickled in a purely chemical manner in the same temperature range in an aqueous solution of 150 g / l HNO3 and 25 g / l HF to remove the chromium-depleted layer.
  • the tape was scale-free, but when pickling in the acid nitrous gases were produced in a concentration of 500 - 800 ppm, which had to be removed from the exhaust gas in the exhaust gas cleaning system.
  • a 10-20% aqueous solution of urea was added to the second pickling bath to reduce the emission of nitrous gases, but the concentration of nitrous gases was reduced from 500-800 ppm to 100-150 ppm, but could not be completely avoided.
  • the acid was then neutralized with sodium hydroxide solution so that an aqueous, neutral solution with a concentration of 200 g / l NaNO3 and 50 g / l NaF was obtained.
  • the pickling tub was equipped with electrodes and these were connected to a rectifier.
  • a scale-free band was also obtained at a current density of 20 A / dm2 and in the same temperature range as in Example 1, but there was no emission of nitrous gases in the suction system.
EP89890225A 1988-09-14 1989-09-01 Procédé pour le décapage d'acier spécial par voie électrolytique Expired - Lifetime EP0359736B1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
AT0225888A AT391486B (de) 1988-09-14 1988-09-14 Verfahren zum elektrolytischen beizen von edelstahlband
AT2258/88 1988-09-14

Publications (2)

Publication Number Publication Date
EP0359736A1 true EP0359736A1 (fr) 1990-03-21
EP0359736B1 EP0359736B1 (fr) 1993-02-03

Family

ID=3530989

Family Applications (1)

Application Number Title Priority Date Filing Date
EP89890225A Expired - Lifetime EP0359736B1 (fr) 1988-09-14 1989-09-01 Procédé pour le décapage d'acier spécial par voie électrolytique

Country Status (9)

Country Link
US (1) US5022971A (fr)
EP (1) EP0359736B1 (fr)
JP (1) JPH0713320B2 (fr)
KR (1) KR950012425B1 (fr)
AT (1) AT391486B (fr)
DE (1) DE58903444D1 (fr)
ES (1) ES2039949T3 (fr)
FI (1) FI90093C (fr)
ZA (1) ZA896965B (fr)

Families Citing this family (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH0774480B2 (ja) * 1991-05-01 1995-08-09 中外炉工業株式会社 ステンレス鋼帯の連続焼鈍酸洗設備
AT399167B (de) * 1991-06-10 1995-03-27 Andritz Patentverwaltung Verfahren und vorrichtung zum elektrolytischen beizen von kontinuierlich durchlaufendem elektrisch leitendem gut
EP0763609B1 (fr) * 1995-09-15 1999-12-15 MANNESMANN Aktiengesellschaft Procédé et dispositif pour le traitement de produits sous forme de bande en acier inoxydable
US6096183A (en) * 1997-12-05 2000-08-01 Ak Steel Corporation Method of reducing defects caused by conductor roll surface anomalies using high volume bottom sprays
AT406486B (de) * 1998-12-22 2000-05-25 Andritz Patentverwaltung Verfahren zum beizen von edelstahl

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
AT1461B (fr) * 1899-06-12 1900-06-11 Ver Elek Citaets Actien Ges
AT213190B (de) * 1958-12-23 1961-01-25 Othmar Ing Ruthner Verfahren zum Beizen von legierten Stählen
AT240674B (de) * 1963-04-25 1965-06-10 Othmar Ing Ruthner Verfahren zum elektrolytischen Beizen von niedriglegierten und Kohlenstoffstählen
AT252685B (de) * 1964-12-22 1967-03-10 Ruthner Ind Planungs Ag Verfahren zum Beizen hochlegierter Stähle und Sonderlegierungen
GB1522535A (en) * 1975-09-26 1978-08-23 Centro Speriment Metallurg Method of surface treatment of a steel component

Family Cites Families (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
AT252674B (de) * 1965-04-09 1967-03-10 Othmar Matzke Zur Aufnahme des Achsdruckes geeignete (lasttragende) Abrollverzahnung
FR2431554A1 (fr) * 1978-07-20 1980-02-15 Ruthner Industrieanlagen Ag Procede pour le decapage electrolytique de bandes laf d'acier inoxydable
AT387406B (de) * 1987-05-07 1989-01-25 Andritz Ag Maschf Verfahren zum elektrolytischen beizen von chromhaeltigem edelstahl

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
AT1461B (fr) * 1899-06-12 1900-06-11 Ver Elek Citaets Actien Ges
AT213190B (de) * 1958-12-23 1961-01-25 Othmar Ing Ruthner Verfahren zum Beizen von legierten Stählen
AT240674B (de) * 1963-04-25 1965-06-10 Othmar Ing Ruthner Verfahren zum elektrolytischen Beizen von niedriglegierten und Kohlenstoffstählen
AT252685B (de) * 1964-12-22 1967-03-10 Ruthner Ind Planungs Ag Verfahren zum Beizen hochlegierter Stähle und Sonderlegierungen
GB1522535A (en) * 1975-09-26 1978-08-23 Centro Speriment Metallurg Method of surface treatment of a steel component

Also Published As

Publication number Publication date
ATA225888A (de) 1990-04-15
FI90093B (fi) 1993-09-15
JPH02107800A (ja) 1990-04-19
FI893978A0 (fi) 1989-08-24
KR900004969A (ko) 1990-04-13
AT391486B (de) 1990-10-10
ES2039949T3 (es) 1993-10-01
US5022971A (en) 1991-06-11
FI893978A (fi) 1990-03-15
KR950012425B1 (en) 1995-10-17
FI90093C (fi) 1993-12-27
DE58903444D1 (de) 1993-03-18
EP0359736B1 (fr) 1993-02-03
ZA896965B (en) 1990-06-27
JPH0713320B2 (ja) 1995-02-15

Similar Documents

Publication Publication Date Title
EP1013800B1 (fr) Procédé de décapage d'acier inoxydable
DE2359021A1 (de) Beizloesung und verfahren zum beizen von metallen
EP0770707A1 (fr) Procédé de fabrication en continu de bandes laminées au froid
DE60102387T2 (de) Methode zum kontinuierlichen elektrolytischen beizen von metallen mittels wechselstrom gespeisten zellen
AT399167B (de) Verfahren und vorrichtung zum elektrolytischen beizen von kontinuierlich durchlaufendem elektrisch leitendem gut
EP0359736B1 (fr) Procédé pour le décapage d'acier spécial par voie électrolytique
DE2621108C2 (de) Verfahren zur stetigen oder schrittweisen elektrochemischen Reinigung legierter Stähle
EP0291493B1 (fr) Procédé de découpage électrolytique d'acier inoxydable contenant du chrome
DE2710459C2 (de) Verfahren zum elektrolytischen Entzundern eines metallischen Körpers und seine Anwendung auf legierten Stahl
DE2642816B2 (de) Stahlbeizverfahren als Vorbehandlung für das Abscheiden von Überzügen auf Stahl
AT395601B (de) Verfahren zum beizen von edelstahl
DE3222532C2 (fr)
DE69932035T2 (de) Verfahren zur behandlung eines metallproduktes
DE1220699B (de) Beizbad fuer rostfreien Stahl
DE19624436A1 (de) Verfahren zur Oberflächenbehandlung von aus Edelstahl bestehendem Behandlungsgut
DE3701728A1 (de) Verfahren zum aufbringen von oxalatueberzuegen auf edelstahl
DE1496906B2 (de) Waessriges bad zum elektrolytischen entzundern von eisen und stahl
EP0814180A1 (fr) Procédé de traitement de surfaces en acier inoxydable
DE2714136C3 (de) Verfahren zum Entzundern eines Körpers aus nichtrostendem Stahl
DE1546077C3 (de) Verfahren zum elektrolytischen Entfernen von Oxiden auf der Oberfläche von Edelstahl
DE3906791A1 (de) Verfahren zur aufbereitung von metallhaltigen, salpetersauren, flusssaeure enthaltenden abfallbeizen
AT272039B (de) Verfahren zur anodischen elektrolytischen Entzunderung von Materialien aus Eisen und Stahl
DE941706C (de) Verfahren zum elektrolytischen Entzundern austenitischer Staehle in alkalischen Loesungen
AT213190B (de) Verfahren zum Beizen von legierten Stählen
DE1496906C3 (de) Wäßriges Bad zum elektrolytischen Entzundern von Eisen und Stahl

Legal Events

Date Code Title Description
PUAI Public reference made under article 153(3) epc to a published international application that has entered the european phase

Free format text: ORIGINAL CODE: 0009012

AK Designated contracting states

Kind code of ref document: A1

Designated state(s): BE DE ES FR GB IT SE

17P Request for examination filed

Effective date: 19900417

17Q First examination report despatched

Effective date: 19920427

GRAA (expected) grant

Free format text: ORIGINAL CODE: 0009210

AK Designated contracting states

Kind code of ref document: B1

Designated state(s): BE DE ES FR GB IT SE

REF Corresponds to:

Ref document number: 58903444

Country of ref document: DE

Date of ref document: 19930318

GBT Gb: translation of ep patent filed (gb section 77(6)(a)/1977)

Effective date: 19930218

ET Fr: translation filed
ITF It: translation for a ep patent filed

Owner name: FUMERO BREVETTI S.N.C.

REG Reference to a national code

Ref country code: ES

Ref legal event code: FG2A

Ref document number: 2039949

Country of ref document: ES

Kind code of ref document: T3

PLBE No opposition filed within time limit

Free format text: ORIGINAL CODE: 0009261

STAA Information on the status of an ep patent application or granted ep patent

Free format text: STATUS: NO OPPOSITION FILED WITHIN TIME LIMIT

26N No opposition filed
EAL Se: european patent in force in sweden

Ref document number: 89890225.9

PGFP Annual fee paid to national office [announced via postgrant information from national office to epo]

Ref country code: GB

Payment date: 19990813

Year of fee payment: 11

PGFP Annual fee paid to national office [announced via postgrant information from national office to epo]

Ref country code: FR

Payment date: 19990817

Year of fee payment: 11

PGFP Annual fee paid to national office [announced via postgrant information from national office to epo]

Ref country code: DE

Payment date: 19990820

Year of fee payment: 11

PGFP Annual fee paid to national office [announced via postgrant information from national office to epo]

Ref country code: SE

Payment date: 19990823

Year of fee payment: 11

PGFP Annual fee paid to national office [announced via postgrant information from national office to epo]

Ref country code: BE

Payment date: 19990827

Year of fee payment: 11

PGFP Annual fee paid to national office [announced via postgrant information from national office to epo]

Ref country code: ES

Payment date: 19990917

Year of fee payment: 11

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: GB

Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES

Effective date: 20000901

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: ES

Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES

Effective date: 20000902

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: SE

Free format text: THE PATENT HAS BEEN ANNULLED BY A DECISION OF A NATIONAL AUTHORITY

Effective date: 20000929

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: BE

Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES

Effective date: 20000930

BERE Be: lapsed

Owner name: MASCHINENFABRIK ANDRITZ A.G.

Effective date: 20000930

GBPC Gb: european patent ceased through non-payment of renewal fee

Effective date: 20000901

EUG Se: european patent has lapsed

Ref document number: 89890225.9

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: FR

Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES

Effective date: 20010531

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: DE

Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES

Effective date: 20010601

REG Reference to a national code

Ref country code: FR

Ref legal event code: ST

REG Reference to a national code

Ref country code: ES

Ref legal event code: FD2A

Effective date: 20011011

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: IT

Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES;WARNING: LAPSES OF ITALIAN PATENTS WITH EFFECTIVE DATE BEFORE 2007 MAY HAVE OCCURRED AT ANY TIME BEFORE 2007. THE CORRECT EFFECTIVE DATE MAY BE DIFFERENT FROM THE ONE RECORDED.

Effective date: 20050901