FR2461765A1 - PROCESS AND INSTALLATION FOR THERMOCHEMICAL STRIPPING OF STAINLESS STEEL PARTS - Google Patents
PROCESS AND INSTALLATION FOR THERMOCHEMICAL STRIPPING OF STAINLESS STEEL PARTS Download PDFInfo
- Publication number
- FR2461765A1 FR2461765A1 FR7919021A FR7919021A FR2461765A1 FR 2461765 A1 FR2461765 A1 FR 2461765A1 FR 7919021 A FR7919021 A FR 7919021A FR 7919021 A FR7919021 A FR 7919021A FR 2461765 A1 FR2461765 A1 FR 2461765A1
- Authority
- FR
- France
- Prior art keywords
- bath
- parts
- soda
- sulfuric
- rinsing
- 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
Links
- 229910001220 stainless steel Inorganic materials 0.000 title claims abstract description 11
- 238000000034 method Methods 0.000 title claims abstract description 10
- 239000010935 stainless steel Substances 0.000 title claims abstract description 10
- 230000008569 process Effects 0.000 title claims abstract description 7
- 238000009434 installation Methods 0.000 title claims description 7
- 239000002253 acid Substances 0.000 claims abstract description 13
- 238000005554 pickling Methods 0.000 claims abstract description 10
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 6
- CDBYLPFSWZWCQE-UHFFFAOYSA-L Sodium Carbonate Chemical compound [Na+].[Na+].[O-]C([O-])=O CDBYLPFSWZWCQE-UHFFFAOYSA-L 0.000 claims description 17
- 238000005266 casting Methods 0.000 claims description 2
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 claims 4
- 240000008042 Zea mays Species 0.000 claims 1
- 235000005824 Zea mays ssp. parviglumis Nutrition 0.000 claims 1
- 235000002017 Zea mays subsp mays Nutrition 0.000 claims 1
- 235000005822 corn Nutrition 0.000 claims 1
- 238000010438 heat treatment Methods 0.000 claims 1
- 239000002351 wastewater Substances 0.000 abstract description 7
- VYZAMTAEIAYCRO-UHFFFAOYSA-N Chromium Chemical compound [Cr] VYZAMTAEIAYCRO-UHFFFAOYSA-N 0.000 abstract description 6
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 description 9
- VWDWKYIASSYTQR-UHFFFAOYSA-N sodium nitrate Chemical compound [Na+].[O-][N+]([O-])=O VWDWKYIASSYTQR-UHFFFAOYSA-N 0.000 description 6
- 229910052804 chromium Inorganic materials 0.000 description 5
- 239000011651 chromium Substances 0.000 description 5
- JOPOVCBBYLSVDA-UHFFFAOYSA-N chromium(6+) Chemical compound [Cr+6] JOPOVCBBYLSVDA-UHFFFAOYSA-N 0.000 description 4
- 238000007654 immersion Methods 0.000 description 4
- 229910052751 metal Inorganic materials 0.000 description 4
- 239000002184 metal Substances 0.000 description 4
- 238000005530 etching Methods 0.000 description 3
- 150000003839 salts Chemical class 0.000 description 3
- 235000010344 sodium nitrate Nutrition 0.000 description 3
- 239000004317 sodium nitrate Substances 0.000 description 3
- GRYLNZFGIOXLOG-UHFFFAOYSA-N Nitric acid Chemical class O[N+]([O-])=O GRYLNZFGIOXLOG-UHFFFAOYSA-N 0.000 description 2
- 229910000831 Steel Inorganic materials 0.000 description 2
- 239000010959 steel Substances 0.000 description 2
- LSNNMFCWUKXFEE-UHFFFAOYSA-M Bisulfite Chemical compound OS([O-])=O LSNNMFCWUKXFEE-UHFFFAOYSA-M 0.000 description 1
- 101100165177 Caenorhabditis elegans bath-15 gene Proteins 0.000 description 1
- PMZURENOXWZQFD-UHFFFAOYSA-L Sodium Sulfate Chemical compound [Na+].[Na+].[O-]S([O-])(=O)=O PMZURENOXWZQFD-UHFFFAOYSA-L 0.000 description 1
- 230000002378 acidificating effect Effects 0.000 description 1
- 230000009471 action Effects 0.000 description 1
- 238000005422 blasting Methods 0.000 description 1
- 229940105847 calamine Drugs 0.000 description 1
- 239000011248 coating agent Substances 0.000 description 1
- 238000000576 coating method Methods 0.000 description 1
- 238000001816 cooling Methods 0.000 description 1
- 238000010908 decantation Methods 0.000 description 1
- 238000012217 deletion Methods 0.000 description 1
- 230000037430 deletion Effects 0.000 description 1
- 238000001914 filtration Methods 0.000 description 1
- 229910052864 hemimorphite Inorganic materials 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 235000014413 iron hydroxide Nutrition 0.000 description 1
- 159000000014 iron salts Chemical class 0.000 description 1
- 229910000358 iron sulfate Inorganic materials 0.000 description 1
- BAUYGSIQEAFULO-UHFFFAOYSA-L iron(2+) sulfate (anhydrous) Chemical compound [Fe+2].[O-]S([O-])(=O)=O BAUYGSIQEAFULO-UHFFFAOYSA-L 0.000 description 1
- NCNCGGDMXMBVIA-UHFFFAOYSA-L iron(ii) hydroxide Chemical compound [OH-].[OH-].[Fe+2] NCNCGGDMXMBVIA-UHFFFAOYSA-L 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- QPJSUIGXIBEQAC-UHFFFAOYSA-N n-(2,4-dichloro-5-propan-2-yloxyphenyl)acetamide Chemical compound CC(C)OC1=CC(NC(C)=O)=C(Cl)C=C1Cl QPJSUIGXIBEQAC-UHFFFAOYSA-N 0.000 description 1
- 229910017604 nitric acid Inorganic materials 0.000 description 1
- 239000007800 oxidant agent Substances 0.000 description 1
- 230000009467 reduction Effects 0.000 description 1
- 238000005096 rolling process Methods 0.000 description 1
- 229910052938 sodium sulfate Inorganic materials 0.000 description 1
- 235000011152 sodium sulphate Nutrition 0.000 description 1
- 230000007928 solubilization Effects 0.000 description 1
- 238000005063 solubilization Methods 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 238000004381 surface treatment Methods 0.000 description 1
- 238000010301 surface-oxidation reaction Methods 0.000 description 1
- 230000009466 transformation Effects 0.000 description 1
- 239000003643 water by type Substances 0.000 description 1
- 239000011787 zinc oxide Substances 0.000 description 1
- 235000014692 zinc oxide Nutrition 0.000 description 1
- CPYIZQLXMGRKSW-UHFFFAOYSA-N zinc;iron(3+);oxygen(2-) Chemical compound [O-2].[O-2].[O-2].[O-2].[Fe+3].[Fe+3].[Zn+2] CPYIZQLXMGRKSW-UHFFFAOYSA-N 0.000 description 1
Classifications
-
- 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
- C23G3/00—Apparatus for cleaning or pickling metallic material
- C23G3/02—Apparatus for cleaning or pickling metallic material for cleaning wires, strips, filaments continuously
-
- 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
- C23G1/28—Cleaning or pickling metallic material with solutions or molten salts with molten salts
- C23G1/32—Heavy metals
Landscapes
- Chemical & Material Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- General Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Mechanical Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Cleaning And De-Greasing Of Metallic Materials By Chemical Methods (AREA)
Abstract
L'INVENTION CONCERNE UN PROCEDE ET UNE INSTALLATION DE DECAPAGE DE PIECES EN ACIER INOXYDABLE PAR VOIE THERMOCHIMIQUE. ELLE CONSISTE A FAIRE PASSER DIRECTEMENT LES PIECES A DECAPER D'UN BAIN DE SOUDE FONDUE A UN BAIN ACIDE SANS ETAPE INTERMEDIAIRE DE RINCAGE A L'EAU. CETTE FACON DE PROCEDER SIMPLIFIE CONSIDERABLEMENT LE TRAITEMENT DES EAUX RESIDUAIRES QUI NE CONTIENNENT PLUS DE CHROME HEXAVALENT.THE INVENTION CONCERNS A PROCESS AND A PLANT FOR PICKLING STAINLESS STEEL PARTS THERMOCHEMALLY. IT CONSISTS OF PASSING THE PARTS TO BE PICKLED DIRECTLY FROM A BATH OF MELTED SODA TO AN ACID BATH WITHOUT AN INTERMEDIATE STEP OF RINSING WITH WATER. THIS WAY OF PROCEEDING CONSIDERABLY SIMPLIFIES THE TREATMENT OF WASTE WATER WHICH NO LONGER CONTAINS HEXAVALENT CHROME.
Description
1. La présente invention concerne le décapage de1. The present invention relates to the blasting of
pièces brutes de fonderie par voie thermochimique. foundry blanks thermochemically.
On sait que la transformation à chaud des lin- We know that the hot transformation of lin-
gots d'acier inoxydable en pièces brutes de fonderie telles que fils, tubes, barres, bandes ou profilés divers se tra- duit, par suite des hautes températures utilisées pour cette transformation, par une oxydation superficielle>appelée calamine, qu'il est nécessaire d'éliminer avant d'effectuer des traitements ultérieurs notamment une transformation à froid par laminage, tréfilage ou étirage ou un revêtement The use of stainless steel in castings, such as wires, tubes, bars, strips or other shapes, results in a surface oxidation, called calamine, which is necessary because of the high temperatures used for this process. to eliminate before further processing including cold processing by rolling, drawing or drawing or coating
métallique de surface par voie chimique ou électrolytique. surface metal chemically or electrolytically.
Le décapage thermochimique classique des piè- The conventional thermochemical stripping of
ces en acier calaminées comprend d'abord une immersion de ces pièces dans un bain de soude fondue, maintenu à 450'C environ et contenant généralement une proportion moindre de nitrate de sodium à titre d'agent oxydant, pour dissoudre un certain nombre d'oxydesd'éléments présents dans les aciers inoxydables. Certains autres oxydes n'étant pas solubles these calaminated steel first comprises an immersion of these parts in a bath of molten soda, maintained at 450 ° C and generally containing a lower proportion of sodium nitrate as an oxidizing agent, to dissolve a number of oxides of elements present in stainless steels. Some other oxides are not soluble
dans la soude doivent être éliminés dans un bain de traite- soda should be removed in a treatment bath.
ment acide ultérieur, qui comprend généralement un bain sul- subsequently acidic acid, which usually
furique pour neutraliser les dernières traces de base et furic to neutralize the last basic traces and
réduire une partie des sels de fer puis un bain fluonitri- reduce some of the iron salts and then a fluonitrile bath.
que pour parachever la solubilisation des derniers sels that to complete the solubilization of the last salts
métalliques recouvrant la surface des pièces à décaper. metal surfaces covering the surface of the parts to be stripped.
Toutefois avant de soumettre au bain d'acide les pièces qui viennent d'être traitées par le bain de soude fondue, il était jusqu'à présent considéré comme nécessaire de prévoir une étape intermédiaire de rinçage de ces pièces à l'eau, pour les refroidir, compléter l'action de la soude en éliminant les oxydes dissous par cette dernière et éviter une consommation d'acide supplémentaire due à la présence However, before subjecting the parts which have just been treated with the bath of molten soda to the acid bath, it has hitherto been considered necessary to provide an intermediate step of rinsing these parts with water, for cool, complete the action of sodium hydroxide by eliminating the oxides dissolved by the latter and avoid additional acid consumption due to the presence
d'un excès de soude.an excess of soda.
Les eaux usées provenant de cette opération de rinçage posent toutefois un grave problème de pollution car However, the wastewater from this rinsing operation is a serious pollution problem because
elles contiennent du chrome soluble à l'état hexavalent con- they contain soluble chromium in the hexavalent state
sidéré comme particulièrement nocif et qui ne peut être considered as particularly harmful and which can not be
rejeté à l'égout.rejected to the sewer.
2. Pour éliminer le chrome hexavalent de ces eaux basiques de rinçage, il est nécessaire de commencer par les acidifier jusqu'à un pH de l'ordre de 2, d'ajouter ensuite du bisulfite pour réduire le chrome à l'état trivalent, et de neutraliser pour précipiter le chrome trivalent qui est 2. To remove hexavalent chromium from these basic rinsing waters, it is necessary to start by acidifying them to a pH of about 2, then adding bisulphite to reduce the chromium to the trivalent state, and neutralize to precipitate trivalent chromium which is
alors éliminé par filtration ou décantation. then removed by filtration or decantation.
La présente invention a pour objet d'apporter un perfectionnement à cette technique de décapage des pièces brutes The present invention aims to provide an improvement to this technique of stripping raw parts
en acier inoxydable et elle consiste à faire passerz direc- in stainless steel and it consists of directing
tement ces pièces du bain de soude fondue au bain de trai- these parts of the bath of molten soda in the treatment bath.
tement acide ultérieur, en supprimant l'étape intermédiaire afterwards, removing the intermediate step
de rinçage à l'eau.rinsing with water.
Elle a également pour objet une installation de décapage thermochimique de pièces en acier inoxydables dans laquelle il y a immersion directe des pièces en It also relates to a thermochemical pickling plant of stainless steel parts in which there is direct immersion of the parts in
provenance du bain de soude fondue dans le bain d'acide. from the bath of molten soda in the acid bath.
La demanderesse a vérifié par analyse chimique qu'il se produit, au sein du bain acide, une auto-réduction du The Applicant has verified by chemical analysis that, within the acid bath, a self-reduction of
chrome hexavalent formé dans le bain de soude. hexavalent chromium formed in the soda bath.
Cette réduction du chrome qui passe à l'état trivalent permet d'éviter les problèmes liés au traitement des eaux de rejets contenant du chrome hexavalent et de supprimer l'étape de rinçage des pièces entre leurs passages This reduction of chromium to a trivalent state avoids the problems associated with the treatment of waste water containing hexavalent chromium and eliminates the step of rinsing the pieces between their passes.
dans les bains de soude fondue et d'acide. in baths of molten soda and acid.
Outre la simplification que cette suppression Besides the simplification that this deletion
représente dans le processus et les installations de déca- represents in the process and the decommissioning facilities
page, le passage direct des pièces d'un bain de soude main- page, the direct passage of the parts of a soda bath
tenu à une température de l'ordre de 450C dans un bain acide dont la température est de l'ordre de 70WC permet de récupérer de la chaleur, qui peut servir dans les étapes held at a temperature of about 450C in an acid bath whose temperature is of the order of 70WC can recover heat, which can be used in the steps
ultérieures du traitement des pièces à décaper. subsequent treatment of the parts to be stripped.
Pour mieux illustrer la présente inventions la figure 1 ci-jointe montre une installation classique de décapage thermochimique et la figure 2 une installation To better illustrate the present invention, FIG. 1, attached, shows a conventional thermochemical etching installation and FIG.
selon l'invention.according to the invention.
Le décapage thermochimique des pièces en acier calaminées s'effectue d'une manière connue par passage dans une succession de bains, représentée sur la figure 1 et 3. comprenant dans l'ordre: a) un bain de soude et de nitrate de sodium fondus 10 chauffé à une température de l'ordre de 370 à The thermochemical etching of the calaminated steel parts is carried out in a known manner by passing through a succession of baths, shown in FIG. 1 and 3. comprising in the following order: a) a molten sodium hydroxide and sodium nitrate bath 10 heated to a temperature of about 370 to
480'C;480'C;
b) un bain de refroidissement et de rinçage 11 b) a cooling and rinsing bath 11
conduisant à un rejet d'eaux usées basiques contenant notam- leading to a discharge of basic wastewater containing in particular
ment du chrome hexavalent; c) un bain de décapage sulfurique 12 chauffé à 70'C environ à l'aide de vapeur; d) un bain de rinçage 13 entraînant le rejet d'eaux usées chargées essentiellement en acide et en sulfate de fer e) un bain de décapage fluonitrique 14 chauffé à 550C à l'aide de vapeur; et enfin f) un bain de rinçage 15 par immersion et sous hexavalent chromium; c) a sulfuric pickling bath 12 heated to about 70 ° C with steam; d) a rinsing bath 13 causing the discharge of wastewater loaded essentially with acid and iron sulfate; e) a fluonitric pickling bath 14 heated to 550C with steam; and finally f) a rinse bath 15 by immersion and under
pression combinés2 et donnant un effluent chargé essentiel- combined pressure2 and giving an effluent
lement de traces d'acides fluorhydrique et nitrique, ainsi traces of hydrofluoric and nitric acids,
que de sels métalliques.than metal salts.
L'installation de décapage selon la présente invention est représentée sur la figure 2, o les éléments The pickling plant according to the present invention is shown in FIG. 2, where the elements
analogues à ceux de la figure 1 portent les mêmes références. similar to those of Figure 1 have the same references.
Elle. se compose essentiellement: a) d'un bain de soude et de nitrate de sodium fondus 10 chauffé à 450'C environ; b) d'un bain de décapage sulfurique maintenu à 700C environ par un échangeur de chaleur 16; c) d'un bain de rinçage 13 entraînant le rejet d'eaux usées chargées essentiellement de sulfate de sodium, d'hydroxyde de fer et de chrome trivalent; She. consists essentially of: a) a molten sodium hydroxide and sodium nitrate bath heated to about 450 ° C; (b) a sulfuric pickling bath maintained at about 700 ° C by a heat exchanger 16; c) a rinsing bath 13 causing the discharge of wastewater loaded mainly sodium sulfate, iron hydroxide and trivalent chromium;
d) d'un bain de décapage fluonitrique 14 chauf- d) a 14-flonish hot-air etching bath
fé à 550C environ par récupération des calories sur le bain sulfurique; et enfin e) d'un bain de rinçage par immersion et sous pression combinés donnant un effluent chargé essentiellement de traces d'acide fluorhydrique et nitrique, ainsi que de about 550 ° C by recovering calories from the sulfuric bath; and finally e) a combined immersion and pressure rinse bath giving an effluent loaded essentially with traces of hydrofluoric and nitric acid, as well as
sels métalliques.metal salts.
Cette installation se distingue essentiellement de celle représentée sur la figure 1 d'une part par la 4. This installation differs essentially from that shown in Figure 1 on the one hand by the 4.
suppression du bain de rinçage 11 et d'autre part par l'ad- removal of the rinsing bath 11 and secondly by the ad-
dition d'un échangeur de chaleur 16; cet échangeur 16 pré- issuing a heat exchanger 16; this exchanger 16 pre-
lève de la chaleur sur le circuit de circulation du bain de décapage sulfurique 12 pour la transmettre au circuit de circulation du bain de décapage fluonitrique 14. Le procédé selon l'invention permet donc d'économiser l'énergie tout en simplifiant considérablement le traitement des eaux résiduaires d'une installation de raises heat on the circulating circuit of the sulfuric pickling bath 12 to transmit it to the circulation circuit of the fluonitric pickling bath 14. The method according to the invention thus allows energy saving while considerably simplifying the treatment of wastewater from an installation of
décapage thermochimique.thermochemical stripping.
Il s'applique pour toutes les pièces en acier inoxydable nécessitant un traitement de surface et convient particulièrement pour le décapage de flls se présentant sous forme de couronnes, de feuillards servant à la fabrication It is applicable for all stainless steel parts requiring a surface treatment and is particularly suitable for stripping crowns, strips for manufacturing
de tubes et de tubes épais pour roulements.- thick tubes and tubes for bearings
5.5.
Claims (7)
Priority Applications (5)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| FR7919021A FR2461765A1 (en) | 1979-07-24 | 1979-07-24 | PROCESS AND INSTALLATION FOR THERMOCHEMICAL STRIPPING OF STAINLESS STEEL PARTS |
| EP80401096A EP0023184A1 (en) | 1979-07-24 | 1980-07-23 | Process and installation for the thermochemical pickling of articles of stainless steel |
| ES493624A ES493624A0 (en) | 1979-07-24 | 1980-07-23 | THERMAL CHEMICAL PICKLING PROCEDURE FOR STAINLESS STEEL PARTS. |
| JP10103780A JPS5620171A (en) | 1979-07-24 | 1980-07-23 | Method and device for acid washing stainless steel product thermochemically |
| ES495055A ES495055A0 (en) | 1979-07-24 | 1980-09-15 | INSTALLATION OF THERMAL CHEMICAL PICKLING OF STAINLESS STEEL PARTS |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| FR7919021A FR2461765A1 (en) | 1979-07-24 | 1979-07-24 | PROCESS AND INSTALLATION FOR THERMOCHEMICAL STRIPPING OF STAINLESS STEEL PARTS |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| FR2461765A1 true FR2461765A1 (en) | 1981-02-06 |
| FR2461765B1 FR2461765B1 (en) | 1981-12-04 |
Family
ID=9228211
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| FR7919021A Granted FR2461765A1 (en) | 1979-07-24 | 1979-07-24 | PROCESS AND INSTALLATION FOR THERMOCHEMICAL STRIPPING OF STAINLESS STEEL PARTS |
Country Status (4)
| Country | Link |
|---|---|
| EP (1) | EP0023184A1 (en) |
| JP (1) | JPS5620171A (en) |
| ES (2) | ES493624A0 (en) |
| FR (1) | FR2461765A1 (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5348628A (en) * | 1991-04-02 | 1994-09-20 | Unitika Ltd. | Method of treating salt bath liquid |
| CN105483739A (en) * | 2015-12-08 | 2016-04-13 | 无锡华工薄板有限公司 | Concentration control system for strip steel acid washing tank |
Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB1035596A (en) * | 1965-06-28 | 1966-07-13 | Allegheny Ludlum Steel | Improvements in or relating to a process of descaling stainless steel |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5157641A (en) * | 1974-11-18 | 1976-05-20 | Nippon Steel Corp | Sutenresukono datsusukeeruhoho |
-
1979
- 1979-07-24 FR FR7919021A patent/FR2461765A1/en active Granted
-
1980
- 1980-07-23 ES ES493624A patent/ES493624A0/en active Granted
- 1980-07-23 EP EP80401096A patent/EP0023184A1/en not_active Withdrawn
- 1980-07-23 JP JP10103780A patent/JPS5620171A/en active Pending
- 1980-09-15 ES ES495055A patent/ES495055A0/en active Granted
Patent Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB1035596A (en) * | 1965-06-28 | 1966-07-13 | Allegheny Ludlum Steel | Improvements in or relating to a process of descaling stainless steel |
Non-Patent Citations (2)
| Title |
|---|
| EXBK/71 * |
| EXBK/74 * |
Also Published As
| Publication number | Publication date |
|---|---|
| JPS5620171A (en) | 1981-02-25 |
| ES8107332A1 (en) | 1981-08-16 |
| EP0023184A1 (en) | 1981-01-28 |
| FR2461765B1 (en) | 1981-12-04 |
| ES495055A0 (en) | 1981-08-16 |
| ES8104434A1 (en) | 1981-04-16 |
| ES493624A0 (en) | 1981-04-16 |
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