CA2055541A1 - Process for nitriding steel workpieces under pressure - Google Patents

Process for nitriding steel workpieces under pressure

Info

Publication number
CA2055541A1
CA2055541A1 CA 2055541 CA2055541A CA2055541A1 CA 2055541 A1 CA2055541 A1 CA 2055541A1 CA 2055541 CA2055541 CA 2055541 CA 2055541 A CA2055541 A CA 2055541A CA 2055541 A1 CA2055541 A1 CA 2055541A1
Authority
CA
Canada
Prior art keywords
nitriding
nitrogen
volume
ammonia
pressure
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.)
Abandoned
Application number
CA 2055541
Other languages
French (fr)
Inventor
Friedrich Preisser
Rudolf Seif
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.)
Evonik Operations GmbH
Original Assignee
Individual
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 Individual filed Critical Individual
Publication of CA2055541A1 publication Critical patent/CA2055541A1/en
Abandoned legal-status Critical Current

Links

Classifications

    • CCHEMISTRY; METALLURGY
    • C23COATING 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
    • C23CCOATING 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
    • C23C8/00Solid 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
    • C23C8/06Solid 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 gases
    • C23C8/08Solid 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 gases only one element being applied
    • C23C8/24Nitriding
    • C23C8/26Nitriding of ferrous surfaces

Landscapes

  • 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)

Abstract

A b s t r a c t In gas nitriding under pressure, substantially non.
porous, thick nitride layers are obtained in a short time providing a mixture of 5 to 95% by volume ammonia and 95 to 5% by volume nitrogen is used and the nitriding process is carried out under a constant pressure above 0.2 MPa.

Description

2~5~
A process for nitriding steel workpieces under pressure Description:

This invention relates to processes for nitriding steel workpieces and in particular, to such processes in a gas atmosphere containing atomic nitrogen at temperatures above 425C and under pressures above 0.2 MPa.
At present, nitride layers are formed on workpieces of steel alloys in a salt bath, by gas nitriding or by plasma nitriding. These layers improve the resistance to corrosion, wear resistance and vibration resistance of the steels. They normally consist of a so-called coupling layer a few micrometres thick over a nitrogen diffusion layer which is generally formed by the above-mentioned processes over process times of the order of 100 hours.
In recent years, gas nitriding in particular has received a considerable impetus, the steel workpieces being heated in an atmosphere of nitrogen-releasing gases, preferably in an atmosphere of ammonia.
US-PS 2,779,697 describes a process for nitriding steels under pressure in gaseous ammonia.
In this process, a pressure vessel is filled with a certain quantity of ammonia and heated to temperatures of 425 to 640C (800 to 1,200F) so that an ammonia pressure of a few bar is built up in the pressure vessel. Nitride layers between 20 and 40 ~m thick are formed in about 15 hours, depending on the quantity of ammonia, the pressure and the temperature. However, this process has not been successfully used in practice.
Accordingly, the problem addressed by the present invention was to provide a process for nitriding steel workpieces in a gas atmosphere containing atomic nitrogen at temperatures above 425C and under pressures above 0.2 MPa, in which non-porous coupling layers up to 50 ~m in 2~aO~4 ~
thickness could be formed in a short time on unalloyed and alloyed steels without any need for speclal pretreatment.
According to the invention, the solution to this problem is characterized in that the gas atmosphere con-sists of 5 to 95% by volume ammonia and 95 to 5% by volume molecular nitrogen and in that nitriding is carried out under constant pressure.
Ammonia which dissociates into hydrogen and nitrogen at relatively high temperatures is used as the gas releas-ing atomic nitrogen. The use of pure ammonia without incorporation of molecular nitrogen leads to distinctly poorer coupling layers. In this way, nitriding layers up to 50 ~m thick are o~tained in 4 to 5 hours.
These coupling layers are substantially non-porous.
The ratio of the 7' phase to the ~ phase can be established through the process parameters and, in the most favorable case, is 100% ~ phase. Austenitic and high-chrome steels can be nitrided without any chemical pretreatment. This process is suitable for treating workpieces in any numbers and without any geometric restrictlon. The number is determined solely by the available furnace size. A chamber furnace can typically be heated to temperatures of up to 1,200C for an absolute internal pressure of 0.2 to 10 MPa.
~he treatment parameters of temperature, time, absolute pressure and partial pressure of the nitrogen-releasing gas -may be adJusteJ tG establish optimal treatment condl~lons for each material. Nitriding temperatures of 500 to 900C
have proved to be favourable. In addition, it is important that the entire nitriding process be carried out under constant pressure. Pressure variations adversely affect the favorable properties and reproducibility of the coup-ling layers. The treatment time is determined by the type of steel and the desired layer thickness.
The invention is illustrated by the following Ex-amples.

2~3 Example 1 A steel of the composition C 45 is nitrided with a gas mixture of 30% by volume ammonia and 70% by volume nitrogen in a pressure-tight chamber furnace under an excess pressure of 2 MPa and at a temperature of 700C. After one hour, a substantially non-porous 40 ~m thick coupling layer has formed.
Example 2 In the case of fast steels, a 100 ~m thick diffusion zone is obtained in 4 hours at 580C/l MPa pressure using a gas atmosphere of 80% by volume ammonia and 20% by volume nitrogen.

Example 3 A substantially non-porous 50 ~m thick coupling layer is obtained on a steel of the composition 16MnCr5 after 2 hours at 550C/8 MPa pressure in a gas atmosphere of 70% by volume ammonia and 30% by volume nitrogen.

Claims

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A process for nitriding steel workpieces in a gas atmosphere containing atomic nitrogen at temperatures above 425°C and under pressures above 0.2 MPa, characterized in that the gas atmosphere consists of 5 to 95% by volume ammonia and 95 to 5% by volume molecular nitrogen and in that nitriding is carried out under constant pressure.
CA 2055541 1990-11-15 1991-11-14 Process for nitriding steel workpieces under pressure Abandoned CA2055541A1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE19904036381 DE4036381C1 (en) 1990-11-15 1990-11-15
DEP4036381.3 1990-11-15

Publications (1)

Publication Number Publication Date
CA2055541A1 true CA2055541A1 (en) 1992-05-16

Family

ID=6418307

Family Applications (1)

Application Number Title Priority Date Filing Date
CA 2055541 Abandoned CA2055541A1 (en) 1990-11-15 1991-11-14 Process for nitriding steel workpieces under pressure

Country Status (9)

Country Link
EP (1) EP0485686A1 (en)
JP (1) JPH076053B2 (en)
BR (1) BR9101780A (en)
CA (1) CA2055541A1 (en)
CS (1) CS336091A3 (en)
DE (1) DE4036381C1 (en)
PL (1) PL289794A1 (en)
RU (1) RU2015197C1 (en)
YU (1) YU47730B (en)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN102994939A (en) * 2013-01-07 2013-03-27 聊城市人和精工轴承有限公司 Vacuum pulse nitriding process used for heat treatment of bearing cage

Families Citing this family (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5292555A (en) * 1990-07-04 1994-03-08 Degussa Aktiengesellschaft Process for applying nitride layers to titanium
DE4115135C1 (en) * 1991-05-08 1992-02-27 Degussa Ag, 6000 Frankfurt, De
CH690019A5 (en) * 1992-07-16 2000-03-31 Giroflex Entwicklungs Ag Supporting frame for a chair, in particular for an adjustable in height and tilt office chair.
TW237484B (en) * 1992-09-16 1995-01-01 Daido Oxygen
DE4333917C2 (en) * 1993-10-05 1994-06-23 Hans Prof Dr Ing Berns Edge embroidery to create a high-strength austenitic surface layer in stainless steels
FR2884879B1 (en) * 2005-04-22 2007-08-03 Stephanois Rech Mec TORQUE OF GUIDE ARMS WHOSE ONE IS OF PARTICULAR STEEL LEADING TO IMPROVED PERFORMANCE.

Family Cites Families (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2779697A (en) * 1955-09-26 1957-01-29 United States Steel Corp Method of nitriding metallic surfaces
FR1319729A (en) * 1962-04-12 1963-03-01 P I M Prodotti Per L Ind Metal Method and furnace for gas phase treatment, carburizing, nitriding and the like on metal parts
GB1510158A (en) * 1976-07-09 1978-05-10 Rolls Royce Motors Ltd Nitriding of steel
GB2055404B (en) * 1979-06-26 1983-02-16 Lucas Industries Ltd Gas nitriding steel

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN102994939A (en) * 2013-01-07 2013-03-27 聊城市人和精工轴承有限公司 Vacuum pulse nitriding process used for heat treatment of bearing cage
CN102994939B (en) * 2013-01-07 2014-08-06 聊城市人和精工轴承有限公司 Vacuum pulse nitriding process used for heat treatment of bearing cage

Also Published As

Publication number Publication date
RU2015197C1 (en) 1994-06-30
PL289794A1 (en) 1992-06-01
JPH04268063A (en) 1992-09-24
DE4036381C1 (en) 1991-08-14
CS336091A3 (en) 1992-06-17
YU50691A (en) 1993-11-16
JPH076053B2 (en) 1995-01-25
EP0485686A1 (en) 1992-05-20
BR9101780A (en) 1992-06-23
YU47730B (en) 1996-01-08

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