EP0232929B1 - Process for facilitating the cold-forming of stainless steel - Google Patents

Process for facilitating the cold-forming of stainless steel Download PDF

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Publication number
EP0232929B1
EP0232929B1 EP87200060A EP87200060A EP0232929B1 EP 0232929 B1 EP0232929 B1 EP 0232929B1 EP 87200060 A EP87200060 A EP 87200060A EP 87200060 A EP87200060 A EP 87200060A EP 0232929 B1 EP0232929 B1 EP 0232929B1
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Prior art keywords
water
stainless steel
oxalate
oxalate coating
coating
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German (de)
French (fr)
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EP0232929A1 (en
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Sakae Sonoda
Morio Iwamoto
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Nihon Parkerizing Co Ltd
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Nihon Parkerizing Co Ltd
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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
    • C23C22/00—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals
    • C23C22/05—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions
    • C23C22/06—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions using aqueous acidic solutions with pH less than 6
    • C23C22/46—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions using aqueous acidic solutions with pH less than 6 containing oxalates

Definitions

  • the invention relates to a method for facilitating the cold forming of stainless steel by applying an oxalate coating and then a lubricant.
  • the oxalation solutions used to produce the oxalate coating contain, as the main constituent, oxalic acid, additives such as fluoride or chloride, which cause the pickling attack, and sodium thiosulfate or the like, which act as accelerators in the formation of crystals in the layer.
  • an oxalate coating of a suitable layer weight can be produced, to which a lubricating layer is applied in a next operation using a metal soap solution or dispersion.
  • a layer system is currently the best form of preparation of stainless steels for cold forming, provided that conventional degrees of deformation are intended.
  • the high-quality and highly corrosion-resistant stainless steels behave disadvantageously with regard to the formation of oxalate coatings, since the layer formation reaction is severely hindered when using conventional oxalation solutions.
  • the content of the bath components causing the pickling attack such as fluoride or chloride, has been increased, but this has the consequence that the treatment time takes longer and the coating formation is unsatisfactory.
  • the object of the invention is to provide a method for facilitating the cold forming of stainless steels, with which in particular the problems mentioned above can be remedied and which also leads to adhesive coatings in the case of highly corrosion-resistant stainless steels, so that even in the case of heavy cold forming, seizure or cold welding is avoided.
  • Particularly suitable water-soluble polymers are polyvinyl alcohol, polyvinyl pyrrolidone, polyethylene glycol; Polyacrylic acid, casein, glue and the like. Polyvinyl alcohol and polyvinyl pyrrolidone are preferred.
  • the concentrations of the active constituents of the oxalation solution are significant in that than with oxalic acid below 20 g / l there is no sufficient reaction with the stainless steel and above 100 g / l no further increase in reactivity can be achieved.
  • the oxide film does not dissolve sufficiently from the stainless steel surface at a concentration below 5 g / l, so that the formation of the coating proceeds with difficulty. At concentrations above 50 g / l there is practically no additional effect.
  • water-soluble polymer do not lead to an improvement in the coating adhesion at concentrations below the lower limit, and the maximum adhesion is reached at concentrations at the upper limit.
  • Metal soaps are particularly suitable as lubricants for application to the oxalate coating.
  • iron soaps are formed by reaction with the oxalate coating and the soap solution.
  • Calcium, barium, zinc soaps and the like dispersed in water give rise to layers of lubricant of the corresponding soaps on the workpiece surface.
  • the oxalate coating is applied by contact with an oxalating solution which has a temperature of 70 to 100 ° C., preferably 85 to 95 ° C.
  • hydroxylammonium sulfate in combination with oxalic acid is able to quickly and easily bring about complete removal of the oxide film and also to accelerate the formation of the oxalate coating.
  • oxalation solutions which additionally contain fluoride and / or chloride can also be used in the process according to the invention.
  • the water-soluble polymer contained in the oxalation solution is firmly incorporated into the oxalate coating during the formation of the coating, so that it is not removed even by water rinsing. As a result of the installation, a high binding and adhesive effect is also achieved.
  • Sodium thiosulfate is used primarily for nucleation and is therefore particularly responsible for the fineness of the oxalate coating produced.
  • lubricant was applied by treatment with a sodium stearate solution (70 g / l; 75'C; 3 min) before the hot air drying.
  • the wire rods treated and weighed with the individual oxalation solutions - as indicated above - were placed in a 5% by weight aqueous solution of chromic acid at 80 ° C. for a period of 15 min. submerged. Then the wire rods were withdrawn and the layer weights converted into g / m 2 .
  • the adhesion or abrasion resistance of the respective oxalate coatings was tested - also with wire rod.
  • the individual wire rods were tested in a reproducible manner and for a certain time that was identical for all samples using an Amsler testing machine (brake pad against wheel principle).
  • the friction body KIMWIPE® from Jujo Kimberly K.K.
  • the weight of the remaining oxalate coating was then determined using the aforementioned method.
  • the pulling speed was 17.8 m / min.
  • the oxalation solutions used in the process according to the invention led in all cases to residual coating weights of more than 2 g / m 2 in the adhesion test, as a result of which superior adhesion to conventional oxatation solutions tested according to comparison is demonstrated.
  • Tube specimens made of Incolloy 800 (20 Cr, 32 Ni) were used as test objects.
  • Example 1 The treatment was carried out according to the procedure of Example 1 (without soaping). The layer weights were then determined, as indicated in Example 1.
  • test results show that proper oxalate coatings were formed using the oxalation process used in the invention. Although they differed somewhat in terms of layer weight, they possessed the properties necessary for cold forming to a sufficient extent.

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  • Chemical & Material Sciences (AREA)
  • General Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Mechanical Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Metal Extraction Processes (AREA)
  • Chemical Treatment Of Metals (AREA)
  • Lubricants (AREA)
  • Heat Treatment Of Sheet Steel (AREA)
  • Heat Treatment Of Steel (AREA)

Abstract

1. Method for facilitating the cold-working of stainless steel by the application of an oxalate coating and subsequent thereto of a lubricant, characterised in that the oxalate coating is applied by contact with an oxalating solution which consists of 20 to 100 g/l oxalic acid, 5 to 50 g/l hydroxylammoniumsulphate, 0.3 to 3 g/l water-soluble polymer and 0.1 to 10 g/l sodium thiosulphate, optionally fluoride and/or chloride additives and constituents of the treated stainless steel which dissolve and usual impurities remainder water.

Description

Die Erfindung betrifft ein Verfahren zur Erleichterung der Kaltumformung von Edelstahl durch Aufbringen eines Oxalatüberzuges und daran anschließend eines Schmiermittels.The invention relates to a method for facilitating the cold forming of stainless steel by applying an oxalate coating and then a lubricant.

Es ist bekannt, Edelstähle zur Erleichterung der Kaltumformung, z. B. durch Rohrzug oder Kaltstauchen, mit einem Oxalatüberzug und einem anschließend aufgebrachten Schmiermittel zu versehen. Die zur Erzeugung des Oxalatüberzuges eingesetzten Oxalatierungslösungen enthalten als Hauptbestandteil Oxalsäure, Zusatzstoffe, wie Fluorid oder Chlorid, die den Beizangriff bewirken, und Natriumthiosulfat oder dergl., die als Beschleuniger bei der Kristatlkeimbildung in der Schicht wirken. Durch Eintauchen des Werkstückes in eine derartige Oxatatierungstösung läßt sich ein Oxalatüberzug von geeignetem Schichtgewicht erzeugen, auf den in einem nächsten Arbeitsgang mit Hilfe einer Metallseifenlösung oder -dispersion eine Schmierschicht aufgebracht wird. Ein solches Schichtsystem stellt die derzeit beste Form der Vorbereitung von Edelstählen für die Kaltumformung dar, sofern herkömmliche Umformungsgrade beabsichtigt sind.It is known to use stainless steels to facilitate cold forming, e.g. B. by tube drawing or cold upsetting, with an oxalate coating and a subsequently applied lubricant. The oxalation solutions used to produce the oxalate coating contain, as the main constituent, oxalic acid, additives such as fluoride or chloride, which cause the pickling attack, and sodium thiosulfate or the like, which act as accelerators in the formation of crystals in the layer. By immersing the workpiece in such an oxidizing solution, an oxalate coating of a suitable layer weight can be produced, to which a lubricating layer is applied in a next operation using a metal soap solution or dispersion. Such a layer system is currently the best form of preparation of stainless steels for cold forming, provided that conventional degrees of deformation are intended.

In jüngerer Zeit geht jedoch der Trend dahin, Edelstähle zunehmend schwereren Kaltumformungsgraden zu unterwerfen. Insbesondere beim Kaltstauchen sinf mitunter Reduktionsgrade von 80% und mehr erwünscht. Bei derartig hohen Umformungsgraden weisen jedoch die nach bekannten Verfahren erzeugten Oxalatüberzüge nicht mehr die erforderliche Haftung auf, so daß der Oxalatüberzug entfernt wird und es zum Anfressen oder Kaltverschweißen kommt. Die Folge ist, daß ein Austausch der Kaltumformungswerkzeuge unvermeidbar ist und ein erheblicher Teil der produzierten Artikel Ausschuß darstellt. Das bedeutet, daß sich Effizienz und Ausstoß bei der Kaltumformung verringern, was mit beträchtlichen Verlusten verbunden ist.More recently, however, the trend has been towards subjecting stainless steels to increasingly severe degrees of cold forming. Reduction levels of 80% and more are sometimes desirable, especially for cold upsetting. With such high degrees of deformation, however, the oxalate coatings produced by known processes no longer have the required adhesion, so that the oxalate coating is removed and corrosion or cold welding occurs. The result is that an exchange of the cold forming tools is inevitable and represents a significant part of the articles produced committee. This means that the efficiency and output during cold forming are reduced, which is associated with considerable losses.

Parallel zum vorgenannten Trend zu zunehmend schwereren Umformungen geht die Forderung nach Edelstählen mit immer höherer Korrosionsfestigkeit, insbesondere beim Einsatz in der chemischen Industrie. Auch bei der Gewinnung von Erdöl mit ständig tiefer reichenden Bohrlöchern, die mit der Einwirkung hochkorrosiver Gase verbunden ist, können die bislang gebräuchlichen Edelstähle nicht mehr eingesetzt werden. Es sind statt dessen solche mit erheblich höherem Korrosionswiderstand erforderlich. Derartige Edelstähle enthalten häufig 20 Gew.-% Nickel und mehr sowie 20 Gew.-% Chrom und mehr.In parallel to the aforementioned trend towards increasingly heavier forming, there is a demand for stainless steels with ever increasing corrosion resistance, particularly when used in the chemical industry. Even in the extraction of crude oil with ever deeper boreholes, which is associated with the action of highly corrosive gases, the previously used stainless steels can no longer be used. Instead, those with significantly higher corrosion resistance are required. Such stainless steels often contain 20% by weight of nickel and more and 20% by weight of chromium and more.

Gerade die hochwertigen und hochkorrosionsfesten Edelstähle verhalten sich hinsichtlich der Ausbildung von Oxalatüberzügen nachteilig, indem die Schichtbildungsreaktion bei Verwendung herkömmlicher Oxalatierungslösungen stark behindert ist. Um mit dem Problem fertig zu werden, hat man den Gehalt der den Beizangriff bewirkenden Badbestandteile, wie Fluorid oder Chlorid, erhöht, was jedoch zur Folge hat, daß die Behandlungsdauer mehr Zeit in Anspruch nimmt und die Überzugsausbildung nicht zufriedenstellend ist.The high-quality and highly corrosion-resistant stainless steels behave disadvantageously with regard to the formation of oxalate coatings, since the layer formation reaction is severely hindered when using conventional oxalation solutions. In order to deal with the problem, the content of the bath components causing the pickling attack, such as fluoride or chloride, has been increased, but this has the consequence that the treatment time takes longer and the coating formation is unsatisfactory.

Die vorgenannten Probleme haben dazu geführt, daß man bei der Erleichterung der Kaltumformung von Edelstählen die Technologie der Erzeugung von Konversionsüberzügen verlassen und sich statt dessen dem Studium der Bildung von nicht mit dem Grundmetall reagierenden Harzüberzügen zugewandt hat. Jedoch sind derartige Harzüberzüge bislang den Oxalatüberzügen noch immer unterlegen.The foregoing problems have resulted in abandoning conversion coating technology in facilitating cold forming of stainless steels, and instead have turned to studying the formation of resin coatings which do not react with the base metal. However, such resin coatings have so far been inferior to oxalate coatings.

Aufgabe der Erfindung ist, ein Verfahren zur Erleichterung der Kaltumformung von Edelstählen bereitszustellen, mit dem insbesondere die vorstehend angesprochenen Probleme behoben werden können und das auch bei hochkorrosionsfesten Edelstählen zu haftfesten Überzügen führt, so daß selbst bei schweren Kaltumformungen ein Anfressen oder Kattverschweißen vermieden wird.The object of the invention is to provide a method for facilitating the cold forming of stainless steels, with which in particular the problems mentioned above can be remedied and which also leads to adhesive coatings in the case of highly corrosion-resistant stainless steels, so that even in the case of heavy cold forming, seizure or cold welding is avoided.

Die Aufgabe wird gelöst, indem das Verfahren der eingangs genannten Art entsprechend der Erfindung derart ausgestaltet wird, daß man den Oxalatüberzug durch Kontakt mit einer Oxalatierungslösung aufbringt, die aus

  • 20 bis 100 g/I Oxalsäure
  • 5 bis 50 g/I Hydroxylammoniumsulfat
  • 0,3 bis 3 g/I wasserlöslichem Polymer und
  • 0,1 bis 10 g/I Natriumthiosulfat gegebenenfalls Fluorid- und/oder Chloridzusätzen sowie aus in Lösung gehenden Bestandteilen des behandelten Edelstahles und üblichen Verunreinigungen Rest Wasser besteht.
The object is achieved in that the method of the type mentioned at the outset is designed in accordance with the invention in such a way that the oxalate coating is applied by contact with an oxalating solution
  • 20 to 100 g / l oxalic acid
  • 5 to 50 g / l hydroxylammonium sulfate
  • 0.3 to 3 g / l of water-soluble polymer and
  • 0.1 to 10 g / l of sodium thiosulfate, optionally fluoride and / or chloride additives, as well as constituents of the treated stainless steel in solution and usual impurities, the rest being water.

Zwar ist es aus der US-A-2 759 862 bekannt ; zwecks Erleichterung der Kaltumformung und vor der Aufbringung von Schmiermittel auf u. a. Edelstahl gemischte Oxalat-/Sulfidüberzüge mit Hilfe von Lösungen zu erzeugen, die Oxalsäure, ein wasserlösliches Sulfat, Borsäure oder ein wasserlösliches Salz hiervon, einen sich in Wasser unter Bildung von S02 und S zersetzenden Schwefel enthaltenden Aktivator, ein Schutzkolloid, Netzmittel, Rest Wasser, enthalten. Als wasserlösliches Sulfat ist jedoch Hydroxylammoniumsulfat, das sich als besonders wirksam erwiesen hat, nicht genannt.It is known from US-A-2,759,862; To facilitate cold forming and prior to the application of lubricants to stainless steel, inter alia, to produce mixed oxalate / sulfide coatings with the aid of solutions containing oxalic acid, a water-soluble sulfate, boric acid or a water-soluble salt thereof, which is in water with the formation of SO 2 and S decomposing sulfur-containing activator, a protective colloid, wetting agent, balance water. However, hydroxylammonium sulfate, which has proven to be particularly effective, is not mentioned as the water-soluble sulfate.

Besonders geeignete wasserlösliche Polymere sind Polyvinylalkohol, Polyvinylpyrrolidon, Polyethylenglykol ; Polyacrylsäure, Kasein, Leim und dergleichen. Polyvinylalkohol und Polyvinylpyrrolidon sind bevorzugt.Particularly suitable water-soluble polymers are polyvinyl alcohol, polyvinyl pyrrolidone, polyethylene glycol; Polyacrylic acid, casein, glue and the like. Polyvinyl alcohol and polyvinyl pyrrolidone are preferred.

Die Konzentrationen der wirksamen Bestandteile der Oxalatierungslösung sind insofern bedeutend, als bezüglich Oxalsäure unterhalb 20 g/l keine ausreichende Reaktion mit dem Edelstahl erfolgt und oberhalb 100 g/I keine weitere Steigerung der Reaktivität erzielbar ist. Hinsichtlich Hydroxylammoniumsulfat erfolgt bei einer Konzentration unterhalb 5 g/l keine ausreichende Auflösung des Oxidfilms von der Edelstahloberfläche, so daß die Überzugsaubildung nur schwer fortschreitet Bei Konzentrationen über 50 g/I tritt praktisch kein zusätzlicher Effekt auf.The concentrations of the active constituents of the oxalation solution are significant in that than with oxalic acid below 20 g / l there is no sufficient reaction with the stainless steel and above 100 g / l no further increase in reactivity can be achieved. With regard to hydroxylammonium sulfate, the oxide film does not dissolve sufficiently from the stainless steel surface at a concentration below 5 g / l, so that the formation of the coating proceeds with difficulty. At concentrations above 50 g / l there is practically no additional effect.

Die Gehalte an wasserlöslichem Polymer führen bei Konzentrationen unterhalb der unteren Grenze zu keiner Verbesserung der Überzugshaftung, bei Konzentrationen an der oberen Grenze ist das Maximum an Haftung erreicht.The contents of water-soluble polymer do not lead to an improvement in the coating adhesion at concentrations below the lower limit, and the maximum adhesion is reached at concentrations at the upper limit.

Bezüglich der Gehalte an Natriumthiosulfat hat sich gezeigt, daß unterhalb 0,1 g/I praktisch keine Kristallkeimbildung auf Edelstahl erfolgt und daß oberhalb 10 g/l starker Geruch von Schwefelverbindungen infolge Zersetzung auftritt, die mit zunehmender Badbenutzung fortschreitet.Regarding the contents of sodium thiosulfate, it has been shown that below 0.1 g / l there is practically no nucleation on stainless steel and that above 10 g / l there is a strong odor of sulfur compounds due to decomposition, which progresses with increasing use of the bath.

Als Schmiermittel zur Aufbringung auf den Oxalatüberzug sind insbesondere Metallseifen geeignet. Bei Einsatz von wäßrigen Lösungen von Natriumseifen werden durch Reaktion mit dem Oxalatüberzug und der Seifenlösung Eisenseifen gebildet. In Wasser dispergierte Kalzium-, Barium-, Zinkseifen und dergl. lassen auf der Werkstückoberfläche Schmiermittelschichten der entsprechenden Seifen entstehen. Im Falle des Kaltziehens ist es zweckmäßig, Metallseifenpulver der vorgenannten Art unmittelbar vor dem Eintritt des Werkstücks in die Matrize aufzubringen.Metal soaps are particularly suitable as lubricants for application to the oxalate coating. When using aqueous solutions of sodium soaps, iron soaps are formed by reaction with the oxalate coating and the soap solution. Calcium, barium, zinc soaps and the like dispersed in water give rise to layers of lubricant of the corresponding soaps on the workpiece surface. In the case of cold drawing, it is expedient to apply metal soap powder of the aforementioned type immediately before the workpiece enters the die.

Gemäß einer bevorzugten Ausgestaltung der Erfindung bringt man den Oxalatüberzug durch Kontakt mit einer Oxalatierungslösung, die eine Temperatur von 70 bis 100 'C, vorzugsweise von 85 bis 95 'C, aufweist, auf.According to a preferred embodiment of the invention, the oxalate coating is applied by contact with an oxalating solution which has a temperature of 70 to 100 ° C., preferably 85 to 95 ° C.

Die mit der Konzeption der Erfindung gewonnenen Erkenntnisse deuten darauf hin, daß die in Oxalatierungslösungen üblichen, den Beizangriff bewirkenden Zusätze, wie Fluorid und Chlorid, nicht in der Lage sind, die auf der Edelstahloberfläche stets befindlichen, kompliziert zusammengesetzten Oxidfilme von Chrom, Nickel und Eisen vollständig aufzulösen. Dies ist jedoch die Voraussetzung für die Ausbildung eines einwandfrei haftenden Oxalatüberzuges.The knowledge gained with the design of the invention indicates that the additives which cause pickling, such as fluoride and chloride, which are customary in oxalation solutions, are not able to remove the complex composite oxide films of chromium, nickel and iron which are always present on the stainless steel surface completely dissolve. However, this is the prerequisite for the formation of a perfectly adhering oxalate coating.

Demgegenüber ist jedoch Hydroxylammoniumsulfat in Verbindung mit Oxalsäure imstande, schnell und einfach eine völlige Entfernung des Oxidfilmes zu bewirken und zudem die Ausbildung des Oxalatüberzuges zu beschleunigen. Dies gilt insbesondere auch bei hochkorrosionsfesten Edelstählen, deren Oxidfilm besonders resistent ist und mit Fluorid- oder Chloridzusätzen kaum entfembar ist. Dessen ungeachtet können auch beim erfindungsgemäßen Verfahren Oxalatierungslösungen zum Einsatz kommen, die zusätzlich Fluorid und/oder Chlorid enthalten.In contrast, however, hydroxylammonium sulfate in combination with oxalic acid is able to quickly and easily bring about complete removal of the oxide film and also to accelerate the formation of the oxalate coating. This applies in particular to highly corrosion-resistant stainless steels, whose oxide film is particularly resistant and can hardly be removed with fluoride or chloride additives. Nevertheless, oxalation solutions which additionally contain fluoride and / or chloride can also be used in the process according to the invention.

Das in der Oxalatierungslösung enthaltene wasserlösliche Polymer wird bei der Überzugsbildung in den Oxalatüberzug fest eingebaut, so daß es auch durch Wasserspülung nicht entfernt wird. Infolge des Einbaues wird zudem ein hoher Binde- und Hafteffekt erzielt.The water-soluble polymer contained in the oxalation solution is firmly incorporated into the oxalate coating during the formation of the coating, so that it is not removed even by water rinsing. As a result of the installation, a high binding and adhesive effect is also achieved.

Natriumthiosulfat dient primär der Keimbildung und ist damit insbesondere für die Feinkömigkeit des erzeugten Oxalatüberzuges verantwortlich.Sodium thiosulfate is used primarily for nucleation and is therefore particularly responsible for the fineness of the oxalate coating produced.

Die Erfindung wird anhand der nachfolgenden Beispiele beispielsweise und näher erläutert.The invention is illustrated by the following examples, for example and in more detail.

Beispiel 1example 1

Es wurden folgende Oxalatierungslösungen eingesetzt :

Figure imgb0001

  • Zum Test dienten
  • 1. Walzdraht der Edelstahlqualität SUS 316 mit den Abmessungen
  • 5 mm Durchmesser
  • 100 nm Länge
  • (warm gewalzt und gebeizt)
  • 2. Rohrluppen der Edelstahlqualität SUS 304 mit den Abmessungen
  • 25 mm Durchmesser
  • 2,5 mm Wandstärke
  • 2 000 mm Länge
  • (kalt gezogen, geglüht und gebeizt)
  • Die vorgenannten Testobjekte wurden nach dem Verfahrensgang
  • Reinigen (alkalischer Reiniger ; 20 g/l ; 80 'C ; 10 min)
  • Wasserspülen
  • Beizen (5 Gew.-% HNO3 ; 5 Gew.-% HF; 60 'C ; 5 min)
  • Wasserspülen
  • Oxalatierung (mit den vorgenannten Lösungen ; 90 °C ; 10 min)
  • Wasserspülen
  • Heißlufttrocknen
The following oxalation solutions were used:
Figure imgb0001
  • Served for the test
  • 1. SUS 316 stainless steel wire rod with the dimensions
  • 5 mm diameter
  • 100 nm length
  • (hot rolled and pickled)
  • 2. Tube blanks of stainless steel quality SUS 304 with the dimensions
  • 25 mm diameter
  • 2.5 mm wall thickness
  • 2,000 mm in length
  • (cold drawn, annealed and pickled)
  • The aforementioned test objects were made after the procedure
  • Clean (alkaline cleaner; 20 g / l; 80 'C; 10 min)
  • Rinse water
  • Pickling (5% by weight HNO 3 ; 5% by weight HF; 60 'C; 5 min)
  • Rinse water
  • Oxalation (with the aforementioned solutions; 90 ° C; 10 min)
  • Rinse water
  • Hot air drying

behandelt.treated.

Im Falle der Rohriuppen erfolgte noch ein Schmiermittelauftrag durch Behandlung mit einer Natriumstearatlösung (70 g/I ; 75 'C ; 3 min) vor der Heißlufttrocknung.In the case of the tubular soup, lubricant was applied by treatment with a sodium stearate solution (70 g / l; 75'C; 3 min) before the hot air drying.

Zur Ermittlung des Gewichtes des erzeugten Oxalatüberzuges wurden die mit den einzelnen Oxalatierungslösungen - wie vorstehend angegeben― behandelten und gewogenen Walzdrähte in eine 5 Gew.-%ige wäßrige Lösung von Chromsäure von 80 °C während einer Dauer von 15 min. getaucht. Dann wurden die Walzdrähte zurückgezogen und die Schichtgewichte in g/m2 umgerechnet.To determine the weight of the oxalate coating produced, the wire rods treated and weighed with the individual oxalation solutions - as indicated above - were placed in a 5% by weight aqueous solution of chromic acid at 80 ° C. for a period of 15 min. submerged. Then the wire rods were withdrawn and the layer weights converted into g / m 2 .

Die Haftung bzw. Abriebfestigkeit der jeweiligen Oxalatüberzüge wurde - ebenfalls bei Walzdraht - geprüft. Hierzu wurden die einzelnen Walzdrähte in reproduzierbarer Weise und für eine bestimmte, für alle Proben identische Zeit mit einer Amsler-Prüfmaschine (Prinzip Bremsklotz gegen Rad) getestet. Der Reibkörper (KIMWIPE® der Fa. Jujo Kimberly K. K.) war mit Aceton getränkt. Anschließend erfolgte die Ermittlung des Gewichtes des verbliebenen Oxalatüberzuges nach der vorgenannten Methode.The adhesion or abrasion resistance of the respective oxalate coatings was tested - also with wire rod. For this purpose, the individual wire rods were tested in a reproducible manner and for a certain time that was identical for all samples using an Amsler testing machine (brake pad against wheel principle). The friction body (KIMWIPE® from Jujo Kimberly K.K.) was impregnated with acetone. The weight of the remaining oxalate coating was then determined using the aforementioned method.

Der Grad der Erleichterung der Kaltumformung wurde mit Hilfe der mit den verschiedenen Oxalatüberzügen versehenen Rohrluppen ermittelt. Die Umformung erfolgte nach dem Stopfenzug in zwei Stufen

  • von 25 mm Durchmesser und 2,6 mm Wandstärke
  • auf 20 mm Durchmesser und 1,85 mm Wandstärke
  • (Querschnittsreduktion 40,3 %) und weiter
  • auf 16 mm Durchmesser und 1,5 mm Wandstärke
  • (Querschnittsreduktion 35,2 %).
The degree of relief of the cold forming was determined with the help of the tube blankets provided with the various oxalate coatings. The forming was done in two stages after the stopper was pulled
  • of 25 mm diameter and 2.6 mm wall thickness
  • on 20 mm diameter and 1.85 mm wall thickness
  • (Cross-sectional reduction 40.3%) and further
  • on 16 mm diameter and 1.5 mm wall thickness
  • (Cross-sectional reduction 35.2%).

Die Ziehgeschwindigkeit lag bei 17,8 m/min.The pulling speed was 17.8 m / min.

Die jeweiligen Testergebnisse sind nachfolgend zusammengestellt.

Figure imgb0002
The respective test results are summarized below.
Figure imgb0002

Die innerhalb des erfindungsgemäßen Verfahrens eingesetzten Oxalatierungslösungen führten beim Haftungstest in allen Fällen zu Restüberzugsgewichten von mehr als 2 g/m2, wodurch die überlegene Haftung gegenüber herkömmlichen, gemäß Vergleich geprüften Oxatatierungslösungen nachgewiesen ist.The oxalation solutions used in the process according to the invention led in all cases to residual coating weights of more than 2 g / m 2 in the adhesion test, as a result of which superior adhesion to conventional oxatation solutions tested according to comparison is demonstrated.

Im Ziehtest an Rohrluppen zeigten sich bei Anwendung des erfindungsgemäßen Verfahrens keinerlei Anfressen oder Kaltverschweißen, wohingegen im Vergleichsversuch in der zweiten Ziehstufe an der inneren Rohroberfläche Anfreßerscheinungen festzustellen waren.In the drawing test on tube blanks, no seizure or cold welding was found when using the method according to the invention, whereas in the comparative test in the second drawing step, signs of seizure were found on the inner tube surface.

Beispiel 2Example 2

Zur Erzeugung der Oxalatüberzüge dienten wiederum die Oxalatierungslösungen gemäß Beispiel 1.The oxalation solutions according to Example 1 were again used to produce the oxalate coatings.

Als Testobjekte wurden Rohrluppen aus lncolloy 800 (20 Cr, 32 Ni)Tube specimens made of Incolloy 800 (20 Cr, 32 Ni) were used as test objects.

  • Durchmesser 25 mmDiameter 25 mm
  • Wandstärke 2 mmWall thickness 2 mm
  • Länge 50 mmLength 50 mm
  • (kalt gezogen, geglüht und gebeizt)(cold drawn, annealed and pickled)
eingesetzt.used.

Die Behandlung erfolgte nach dem Verfahrensgang des Beispiels 1 (ohne Beseifung). Anschließend wurden - wie im Beispiel 1 angegeben - die Schichtgewichte bestimmt.

Figure imgb0003
The treatment was carried out according to the procedure of Example 1 (without soaping). The layer weights were then determined, as indicated in Example 1.
Figure imgb0003

Die Testergebnisse zeigen, daß mit Hilfe des innerhalb der Erfindung eingesetzten Oxalatierverfahrens einwandfreie Oxalatüberzüge gebildet wurden. Obgleich sie hinsichtlich des Schichtgewichtes gewisse Unterschiede aufwiesen, besaßen sie die für die Kaltumformung notwendigen Eigenschaften in ausreichendem Maße.The test results show that proper oxalate coatings were formed using the oxalation process used in the invention. Although they differed somewhat in terms of layer weight, they possessed the properties necessary for cold forming to a sufficient extent.

Demgegenüber wurden mit den beim Vergleich eingesetzten Oxalatierungslösungen keine Oxalatüberzüge ausgebildet.In contrast, no oxalate coatings were formed with the oxalation solutions used in the comparison.

Claims (5)

1. Method for facilitating the cold-working of stainless steel by the application of an oxalate coating and subsequent thereto of a lubricant, characterised in that the oxalate coating is applied by contact with an oxalating solution which consists of
20 to 100 g/I oxalic acid,
5 to 50 g/I hydroxylammoniumsulphate,
0.3 to 3 g/I water-soluble polymer and
0.1 to 10 g/I sodium thiosulphate, optionally fluoride and/or chloride additives and constituents of the treated stainless steel which dissolve and usual impurities remainder water.
2. Method according to Claim 1, characterised in that the oxalate coating is applied by contact with an oxalating solution which contains polyvinyl alcohol and/or polyvinyl pyrrolidone as a water-soluble polymer.
3. Method according to Claim 1, characterised in that the oxalate coating is applied by contact with an oxalating solution which contains polyethylene glycol, polyacrylic acid, casein and/or glue as the water-soluble polymer.
4. Method according to Claim 1, 2 or 3, characterised in that the oxalate coating is applied by contact with an oxalating solution which has a temperature of 70 to 100 'C.
5. Method according to Claim 4, characterised in that the oxalate coating is applied by contact with an oxalating solution which has a temperature of 85 to 95 'C.
EP87200060A 1986-01-21 1987-01-16 Process for facilitating the cold-forming of stainless steel Expired - Lifetime EP0232929B1 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AT87200060T ATE51423T1 (en) 1986-01-21 1987-01-16 PROCESSES TO FACILITATE THE COLD FORMING OF STAINLESS STEEL.

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
JP10752/86 1986-01-21
JP61010752A JPS62170484A (en) 1986-01-21 1986-01-21 Method for lubricating stainless steel before cold working

Publications (2)

Publication Number Publication Date
EP0232929A1 EP0232929A1 (en) 1987-08-19
EP0232929B1 true EP0232929B1 (en) 1990-03-28

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JP2002088387A (en) * 2000-09-14 2002-03-27 Sakai Chem Ind Co Ltd Metal processing using lubricant composition not containing chlorine
ITMN20060021A1 (en) * 2006-03-23 2007-09-24 Gilcotubi S R L PRODUCTION SYSTEM FOR STAINLESS AND WELDABLE TUBULAR STRUCTURES WITH HIGH MECHANICAL RESISTANCE AND ITS PRODUCT OBTAINED
US11607929B2 (en) 2018-08-09 2023-03-21 Hanon Systems Thermal cycle resistant fastening system for refrigerant fitting
CN113454196A (en) * 2019-02-14 2021-09-28 凯密特尔有限责任公司 Simplified method for pretreating metal substrates for cold forming and reactive lubricant for this purpose
CA3168965A1 (en) 2020-02-25 2021-09-02 Yinfeng SHI One-step pretreatment method of metallic substrates for metal cold forming
EP4110889A1 (en) 2020-02-25 2023-01-04 Chemetall GmbH One-step pretreatment method of metallic substrates for metal cold forming
CN111500955B (en) * 2020-04-17 2021-08-24 抚顺特殊钢股份有限公司 Manufacturing process of N06625 alloy profiled bar for nuclear power evaporator
WO2022207901A1 (en) 2021-04-01 2022-10-06 Chemetall Gmbh One-step pretreatment method of metallic substrates at non-neutral ph values for metal cold forming

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US2759862A (en) * 1952-03-11 1956-08-21 Devex Corp Coating compositions and method of treating ferrous surfaces therewith
CA930651A (en) * 1971-01-12 1973-07-24 Her Majesty The Queen In Right Of Canada As Represented By The Minister Of Energy, Mines, And Resources Forming oxalate conversion coatings on iron or steel
JPS524255B2 (en) * 1972-08-26 1977-02-02
DE2424382A1 (en) * 1974-05-20 1975-12-04 Metallgesellschaft Ag PROCESS FOR THE PREPARATION OF METALLIC WORKPIECES FOR CHIPLESS COLD FORMING

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JPS62170484A (en) 1987-07-27
DE3762053D1 (en) 1990-05-03
DE3700933A1 (en) 1987-07-30
EP0232929A1 (en) 1987-08-19
JPH0129872B2 (en) 1989-06-14

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