EP0421236B1 - Process for the nitrocarburizing of steel pieces - Google Patents

Process for the nitrocarburizing of steel pieces Download PDF

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Publication number
EP0421236B1
EP0421236B1 EP90118366A EP90118366A EP0421236B1 EP 0421236 B1 EP0421236 B1 EP 0421236B1 EP 90118366 A EP90118366 A EP 90118366A EP 90118366 A EP90118366 A EP 90118366A EP 0421236 B1 EP0421236 B1 EP 0421236B1
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EP
European Patent Office
Prior art keywords
nitrocarburizing
stage
minutes
treatment
carried out
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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.)
Expired - Lifetime
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EP90118366A
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German (de)
French (fr)
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EP0421236A1 (en
Inventor
Georg Dipl.-Ing. Wahl
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Houghton Durferrit degussa-Huels AG GmbH
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Degussa GmbH
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Priority to AT90118366T priority Critical patent/ATE89333T1/en
Publication of EP0421236A1 publication Critical patent/EP0421236A1/en
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Publication of EP0421236B1 publication Critical patent/EP0421236B1/en
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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
    • C23C8/00—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals
    • C23C8/40—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using liquids, e.g. salt baths, liquid suspensions
    • C23C8/52—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using liquids, e.g. salt baths, liquid suspensions more than one element being applied in one step
    • C23C8/54—Carbo-nitriding
    • C23C8/56—Carbo-nitriding of ferrous surfaces

Definitions

  • the invention relates to a method for nitrocarburizing steel components in cyanate- and cyanide-containing molten salts at temperatures of 560 to 700 o C.
  • molten salts from mixtures of alkali cyanides, alkali cyanates and alkali carbonates are used, which are usually operated at temperatures of 560 to 590 o C.
  • Such salt baths are known for example from DE-PS 1 149 035.
  • nitrocarburizing salt baths that work at higher temperatures up to 700 oC .
  • the workpieces are exposed to the action of the molten salt for some time, with nitrogen and carbon diffusing into the workpieces and iron carbonitride phases being formed in the surface layers. These phases particularly increase the wear resistance and corrosion resistance of the components.
  • the nitrogen and carbon supply of the molten salt, the treatment temperature and the treatment time influence the structure, the thickness and the quality of the nitrocarburizing layer.
  • nitrocarburizing treatment is carried out in the salt baths containing cyanate and cyanide, for example at 580 o C, components are obtained which have very good properties with regard to wear and corrosion resistance.
  • the reason for this is the formation of a monophase ⁇ -iron carbonitride layer.
  • 580 o C relatively long periods of time are necessary, which are normally several hours.
  • the nitrocarburizing treatment is carried out in a first stage at 600 to 700 o C and in a second stage at 560 to 590 o C, the Nitrocarburizing times of the two stages can range from 20: 1 to 1:15.
  • the treatment is preferably carried out in the first stage at 610 to 650 ° C. for 10 to 120 minutes and in the second stage at 570 to 590 ° C. for 10 to 90 minutes.
  • connection layer With this two-stage treatment, a sufficiently thick connection layer can be achieved in a relatively short time, which surprisingly has the same properties as a connection layer that is formed in considerably longer periods at temperatures of 560 to 590 ° C. This makes it possible to shorten the nitrocarburizing time considerably without deteriorating the quality of the treated components with regard to wear, corrosion, fatigue strength and others.
  • Figures 1 and 2 show a graphical representation of the corrosion behavior (Fig. 1) and the wear resistance (Fig. 2) of samples made of steel CK 45 after treatment in a molten salt with 2.8% by weight cyanide and 37.4% by weight. % Cyanate at different temperatures.
  • Fig. 1 compares the corrosion resistance of cylindrical samples after nitrocarburizing. In all cases the treatment was carried out so that a connecting layer thickness of about 15 ⁇ m was present.
  • the left bar shows the corrosion resistance of piston rods that were nitrocarburized for 90 minutes at 580 o C.
  • the middle bar shows the resistance of the parts after 30 minutes nitrocarburizing at 630 o C and the right bar shows the resistance of samples, the first 20 minutes at 630 o and then 20 minutes at 580 o C have been nitrocarburized.
  • the wear behavior is also favorably influenced by the two-stage treatment according to the invention.
  • the result of an Amsler test is shown in Figure 2.
  • Curve 1 corresponds to the normal treatment of samples made of material C45, 90 minutes at 580 o C;
  • curve 2 was determined on samples which had been nitrocrubbed for 30 minutes at 630 o C and the result of the two-stage nitrocarburization, 20 minutes 630 o C and 20 minutes 580 o C, shows curve 3.
  • the wear behavior of a component that lasted 20 minutes at 630 o C and then treated for 20 minutes at 580 o is comparable to that of a component that was nitrocarburized for 90 minutes at 580 o C.
  • the treatment time is thus more than halved with the method according to the invention.

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  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Mechanical Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Solid-Phase Diffusion Into Metallic Material Surfaces (AREA)
  • Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
  • Artificial Fish Reefs (AREA)
  • Heat Treatment Of Steel (AREA)
  • Fire-Extinguishing Compositions (AREA)
  • Bulkheads Adapted To Foundation Construction (AREA)
  • Investigating And Analyzing Materials By Characteristic Methods (AREA)
  • Treatment Of Steel In Its Molten State (AREA)
  • Chemical Treatment Of Metals (AREA)
  • Preventing Corrosion Or Incrustation Of Metals (AREA)
  • Conveying And Assembling Of Building Elements In Situ (AREA)
  • Placing Or Removing Of Piles Or Sheet Piles, Or Accessories Thereof (AREA)
  • Catalysts (AREA)

Abstract

Steel pieces can be nitrocarburised within relatively short times in salt baths containing cyanate and cyanide, if the treatment is carried out at 600 to 700 DEG C in a first stage and at 560 to 590 DEG C in a second stage. The pieces show the same or better properties as in considerably longer treatment at 560 to 590 DEG C.

Description

Die Erfindung betrifft ein Verfahren zum Nitrocarburieren von Bauteilen aus Stahl in cyanat- und cyanidhaltigen Salzschmelzen bei Temperaturen von 560 bis 700o C.The invention relates to a method for nitrocarburizing steel components in cyanate- and cyanide-containing molten salts at temperatures of 560 to 700 o C.

Zum Nitrocarburieren von Teilen aus Eisen und Stahl werden überwiegend Salzschmelzen aus Gemischen von Alkalicyaniden, Alkalicyanaten und Alkalicarbonaten verwendet, die meist bei Temperaturen von 560 bis 590o C betrieben werden. Solche Salzbäder sind beispielsweise aus der DE-PS 1 149 035 bekannt. Es gibt jedoch auch Nitrocarburiersalzbäder, in denen bei höheren Temperaturen bis zu 700oC gearbeitet wird.For the nitrocarburizing of parts made of iron and steel, mainly molten salts from mixtures of alkali cyanides, alkali cyanates and alkali carbonates are used, which are usually operated at temperatures of 560 to 590 o C. Such salt baths are known for example from DE-PS 1 149 035. However, there are also nitrocarburizing salt baths that work at higher temperatures up to 700 oC .

Die Werkstücke werden der Einwirkung der Salzschmelze einige Zeit ausgesetzt, wobei Stickstoff und Kohlenstoff in die Werkstücke eindiffundiert und Eisencarbonitridphasen in den Oberflächenschichten ausgebildet werden. Diese Phasen erhöhen insbesondere die Verschleißfestigkeit und Korrosionsbeständigkeit der Bauteile. Das Stickstoff- und Kohlenstoffangebot der Salzschmelze, die Behandlungstemperatur und die Behandlungszeit beeinflussen den Aufbau, die Dicke und die Qualität der Nitrocarburierschicht.The workpieces are exposed to the action of the molten salt for some time, with nitrogen and carbon diffusing into the workpieces and iron carbonitride phases being formed in the surface layers. These phases particularly increase the wear resistance and corrosion resistance of the components. The nitrogen and carbon supply of the molten salt, the treatment temperature and the treatment time influence the structure, the thickness and the quality of the nitrocarburizing layer.

Wird die Nitrocarburierbehandlung in den cyanat- und cyanidhaltigen Salzbädern beispielsweise bei 580o C durchgeführt, so erhält man Bauteile, die sehr gute Eigenschaften bezüglich Verschleiß- und Korrosionswiderstand aufweisen. Grund hierfür ist die Ausbildung einer monophasigen ε-Eisencarbonitridschicht. Zu deren Ausbildung in genügender Schichtdicke und Qualtiät sind bei 580o C jedoch relativ lange Zeiträume notwendig, die normalerweise mehrere Stunden betragen.If the nitrocarburizing treatment is carried out in the salt baths containing cyanate and cyanide, for example at 580 o C, components are obtained which have very good properties with regard to wear and corrosion resistance. The reason for this is the formation of a monophase ε-iron carbonitride layer. For their formation in sufficient layer thickness and quality, however, at 580 o C relatively long periods of time are necessary, which are normally several hours.

Bei höheren Temperaturen, beispielsweise 630o C, werden in kürzeren Zeiten entsprechende Schichtdicken von ε-Eisencarbonitrid erzeugt, jedoch ist der Verschleißwiderstand und die Korrosionsbeständigkeit der so behandelten Bauteile deutlich geringer als von Bauteilen die bei 580o in den gleichen Salzschmelzen behandelt werden.At higher temperatures, e.g. 630 o C, corresponding layer thicknesses of ε-iron carbonitride are generated in shorter times, however, the wear resistance and the corrosion resistance of the components treated in this way are significantly lower than for components that are treated at 580 o in the same molten salts.

Es war daher Aufgabe der vorliegenden Erfindung, ein Verfahren zum Nitrocarburieren von Bauteilen aus Stahl in cyanat- und cyanidhaltigen Salzschmelzen bei Temperaturen von 560 bis 700o C zu finden, bei dem die Bauteile gute Verschleiß- und Korrosionseigenschaften bei möglichst kurzer Behandlungszeit aufweisen sollten.It is an object of the present invention, a process for nitrocarburizing components made from steel in cyanate and cyanide-containing salt melts to find out at temperatures from 560 to 700 o C, in which the components good wear and corrosion characteristics should have at the shortest possible treatment time.

Diese Aufgabe wird erfindugnsgemäß dadurch gelöst, daß die Nitrocarburierbehandlung in einer ersten Stufe bei 600 bis 700o C und in einer zweiten Stufe bei 560 bis 590o C durchgeführt wird, wobei die Nitrocarburierzeiten der beiden Stufen sich im Verhältnis von 20 : 1 bis 1 : 15 erstrecken können.This object is achieved according to the invention in that the nitrocarburizing treatment is carried out in a first stage at 600 to 700 o C and in a second stage at 560 to 590 o C, the Nitrocarburizing times of the two stages can range from 20: 1 to 1:15.

Vorzugsweise wird die Behandlung in der ersten Stufe bei 610 bis 650o C während 10 bis 120 Minuten und in der zweiten Stufe bei 570 bis 590o C während 10 bis 90 Minuten durchgeführt.The treatment is preferably carried out in the first stage at 610 to 650 ° C. for 10 to 120 minutes and in the second stage at 570 to 590 ° C. for 10 to 90 minutes.

Mit dieser Zweistufenbehandlung erreicht man in relativ kurzer Zeit eine ausreichend dicke Verbindungsschicht, die überraschenderweise die gleichen Eigenschaften aufweist wie eine Verbindungsschicht, die in wesentlich längeren Zeiträumen bei Temperaturen von 560 bis 590o C entsteht. Dadurch ist es möglich, die Nitrocarburierdauer erheblich zu verkürzen, ohne die Qualität der behandelten Bauteile in bezug auf Verschleiß, Korrosion, Dauerfestigkeit u.a. zu verschlechtern.With this two-stage treatment, a sufficiently thick connection layer can be achieved in a relatively short time, which surprisingly has the same properties as a connection layer that is formed in considerably longer periods at temperatures of 560 to 590 ° C. This makes it possible to shorten the nitrocarburizing time considerably without deteriorating the quality of the treated components with regard to wear, corrosion, fatigue strength and others.

Die Abbildungen 1 und 2 zeigen in graphischer Darstellung das Korrosionsverhalten (Abb. 1) und die Verschließbeständigkeit (Abb. 2) von Proben aus Stahl CK 45 nach der Behandlung in einer Salzschmelze mit 2,8 Gew. % Cyanid und 37,4 Gew. % Cyanat bei verschiedenen Temperaturen.Figures 1 and 2 show a graphical representation of the corrosion behavior (Fig. 1) and the wear resistance (Fig. 2) of samples made of steel CK 45 after treatment in a molten salt with 2.8% by weight cyanide and 37.4% by weight. % Cyanate at different temperatures.

In der Abb. 1 wird der Korrosionswiderstand von zylindrischen Proben nach dem Nitrocarburieren verglichen. In allen Fällen wurde die Behandlung so durchgeführt, daß eine Verbindungsschichtdicke von etwa 15 µm vorlag. Der linke Balken zeigt die Korrosionsbeständigkeit von Kolbenstangen, die 90 Minuten bei 580o C nitrocarburiert wurden. Der mittlere Balken zeigt die Beständigkeit der Teile nach 30 Minuten Nitrocarburieren bei 630oC und der rechte Balken zeigt die Beständigkeit von Proben, die zunächst 20 Minuten bei 630o und anschließend 20 Minuten bei 580o C nitrocarburiert wurden.Fig. 1 compares the corrosion resistance of cylindrical samples after nitrocarburizing. In all cases the treatment was carried out so that a connecting layer thickness of about 15 µm was present. The left bar shows the corrosion resistance of piston rods that were nitrocarburized for 90 minutes at 580 o C. The middle bar shows the resistance of the parts after 30 minutes nitrocarburizing at 630 o C and the right bar shows the resistance of samples, the first 20 minutes at 630 o and then 20 minutes at 580 o C have been nitrocarburized.

Auch das Verschleißverhalten wird durch die erfindungsgemäße Zweistufenbehandlung günstig beeinflußt. Das Ergebnis eines Amsler-Tests ist in Abbildung 2 dargestellt. Die Kurve 1 entspricht der Normalbehandlung von Proben aus dem Werkstoff C45, 90 Minuten bei 580o C; die Kurve 2 wurde an Proben ermittelt, die 30 Minuten bei 630o C nitrocrburiert wurden und das Ergebnis der Zweistufennitrocarburierung, 20 Minuten 630o C und 20 Minuten 580o C, zeigt die Kurve 3. Das Verschleißverhalten eines Bauteils, das 20 Minuten bei 630o C und dann 20 Minuten bei 580o behandelt wurde ist also vergleichbar mit dem eines Bauteils, das 90 Minuten bei 580o C nitrocarburiert wurde. Die Behandlungszeit wird mit dem erfindungsgemäßen Verfahren also mehr als halbiert.The wear behavior is also favorably influenced by the two-stage treatment according to the invention. The result of an Amsler test is shown in Figure 2. Curve 1 corresponds to the normal treatment of samples made of material C45, 90 minutes at 580 o C; curve 2 was determined on samples which had been nitrocrubbed for 30 minutes at 630 o C and the result of the two-stage nitrocarburization, 20 minutes 630 o C and 20 minutes 580 o C, shows curve 3. The wear behavior of a component that lasted 20 minutes at 630 o C and then treated for 20 minutes at 580 o is comparable to that of a component that was nitrocarburized for 90 minutes at 580 o C. The treatment time is thus more than halved with the method according to the invention.

Claims (2)

  1. Process for nitrocarburizing components made from steel in cyanate- and cyanide-containing salt melts at temperatures between 560 and 700°C,
    characterised in that
    the nitrocarburizing process is carried out in a first stage at 600 to 700°C and in a second stage at 560 to 590°C, whereby the nitrocarburizing times of the two stages may be within a range from 20 : 1 to 1 : 15.
  2. Process according to claim 1,
    characterised in that
    in the first stage the process is carried out for 10 to 120 minutes at 610 to 650°C, and in the second stage for 10 to 90 minutes at 570 to 590°C.
EP90118366A 1989-10-04 1990-09-25 Process for the nitrocarburizing of steel pieces Expired - Lifetime EP0421236B1 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AT90118366T ATE89333T1 (en) 1989-10-04 1990-09-25 PROCESS FOR NITROCARBURIZING STEEL COMPONENTS.

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE3933053A DE3933053C1 (en) 1989-10-04 1989-10-04
DE3933053 1989-10-04

Publications (2)

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EP0421236A1 EP0421236A1 (en) 1991-04-10
EP0421236B1 true EP0421236B1 (en) 1993-05-12

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US (1) US5102476A (en)
EP (1) EP0421236B1 (en)
JP (1) JP3001949B2 (en)
AT (1) ATE89333T1 (en)
BR (1) BR9004967A (en)
CA (1) CA2026902C (en)
CS (1) CS9004790A3 (en)
DE (2) DE3933053C1 (en)
DK (1) DK0421236T3 (en)
ES (1) ES2055263T3 (en)
PT (1) PT95496B (en)
RU (1) RU1833436C (en)
TR (1) TR24861A (en)
YU (1) YU183690A (en)
ZA (1) ZA907704B (en)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6093303A (en) * 1998-08-12 2000-07-25 Swagelok Company Low temperature case hardening processes
US6165597A (en) * 1998-08-12 2000-12-26 Swagelok Company Selective case hardening processes at low temperature

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US5525165A (en) * 1994-06-06 1996-06-11 National Science Council Method of surface modification of titanium alloy
DE4442328C1 (en) * 1994-11-29 1995-09-21 Durferrit Thermotechnik Gmbh Pretreating chrome or nickel alloy steels prior to nitro:carburisation in a salt bath
FR2731232B1 (en) * 1995-03-01 1997-05-16 Stephanois Rech PROCESS FOR TREATING FERROUS SURFACES SUBJECT TO HIGH FRICTION STRESS
US6547888B1 (en) 2000-01-28 2003-04-15 Swagelok Company Modified low temperature case hardening processes
US8099364B2 (en) * 2001-05-31 2012-01-17 Contentguard Holdings, Inc. Digital rights management of content when content is a future live event
US6656293B2 (en) 2001-12-10 2003-12-02 Caterpillar Inc Surface treatment for ferrous components
US20030155045A1 (en) * 2002-02-05 2003-08-21 Williams Peter C. Lubricated low temperature carburized stainless steel parts
DE102004022248B4 (en) * 2004-05-04 2007-06-14 Zf Friedrichshafen Ag Process for the production of balls or ball segments, as well as subsequently manufactured ball element for two-part ball studs
US7556699B2 (en) * 2004-06-17 2009-07-07 Cooper Clark Vantine Method of plasma nitriding of metals via nitrogen charging
US7695573B2 (en) * 2004-09-09 2010-04-13 Sikorsky Aircraft Corporation Method for processing alloys via plasma (ion) nitriding
US20060048857A1 (en) * 2004-09-09 2006-03-09 Cooper Clark V Method for processing alloys via high-current density ion implantation
WO2006071502A2 (en) * 2004-12-23 2006-07-06 United Technologies Corporation Composition and process for enhanced properties of ferrous components
PL2881493T3 (en) 2013-12-06 2017-02-28 Hubert Stüken GmbH & Co. KG Process for the nitrocarburization of a deep drawn article or a bent pressed article made of austenitic stainless steel
EP2881492B1 (en) 2013-12-06 2017-05-03 Hubert Stüken GMBH & CO. KG Method for carburising metal deep drawn article or a bent pressed article made of austenitic stainless steel
CN106741205A (en) * 2016-12-27 2017-05-31 北京新能源汽车股份有限公司 The manufacture method of bonnet louver and bonnet louver
CN109338280B (en) * 2018-11-21 2021-11-05 中国航发哈尔滨东安发动机有限公司 Nitriding method after third-generation carburizing steel

Family Cites Families (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1893077A (en) * 1930-09-26 1933-01-03 Garweg August Hardening medium and process for hardening tools of iron or steel
FR971798A (en) * 1947-09-19 1951-01-22 United Western Corp Process for the formation of nitride layers on iron and steel
GB1185640A (en) * 1966-12-21 1970-03-25 Ici Ltd Process for Casehardening Steels

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6093303A (en) * 1998-08-12 2000-07-25 Swagelok Company Low temperature case hardening processes
US6165597A (en) * 1998-08-12 2000-12-26 Swagelok Company Selective case hardening processes at low temperature

Also Published As

Publication number Publication date
ATE89333T1 (en) 1993-05-15
RU1833436C (en) 1993-08-07
DK0421236T3 (en) 1993-10-11
ZA907704B (en) 1992-03-25
PT95496A (en) 1991-06-25
CS275177B2 (en) 1992-02-19
ES2055263T3 (en) 1994-08-16
JP3001949B2 (en) 2000-01-24
CS9004790A3 (en) 1992-02-19
PT95496B (en) 1997-09-30
CA2026902A1 (en) 1991-04-05
JPH03177559A (en) 1991-08-01
CA2026902C (en) 1998-12-01
US5102476A (en) 1992-04-07
YU183690A (en) 1992-12-21
EP0421236A1 (en) 1991-04-10
DE3933053C1 (en) 1990-05-03
TR24861A (en) 1992-07-01
BR9004967A (en) 1991-09-10
DE59001435D1 (en) 1993-06-17

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