EP0059803A1 - Verfahren zum Einsatzhärten von Stahl - Google Patents

Verfahren zum Einsatzhärten von Stahl Download PDF

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Publication number
EP0059803A1
EP0059803A1 EP19810300922 EP81300922A EP0059803A1 EP 0059803 A1 EP0059803 A1 EP 0059803A1 EP 19810300922 EP19810300922 EP 19810300922 EP 81300922 A EP81300922 A EP 81300922A EP 0059803 A1 EP0059803 A1 EP 0059803A1
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EP
European Patent Office
Prior art keywords
bath
process according
case
urea
temperature
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Granted
Application number
EP19810300922
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English (en)
French (fr)
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EP0059803B1 (de
Inventor
Thomas Michael Jakubowski
William George Wood
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Kolene Corp
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Kolene Corp
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Publication date
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Priority to DE8181300922T priority Critical patent/DE3173690D1/de
Priority to EP19810300922 priority patent/EP0059803B1/de
Publication of EP0059803A1 publication Critical patent/EP0059803A1/de
Application granted granted Critical
Publication of EP0059803B1 publication Critical patent/EP0059803B1/de
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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
    • 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
    • C23C8/42—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 only one element being applied
    • C23C8/44—Carburising
    • C23C8/46—Carburising of ferrous surfaces
    • 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
    • C23C8/42—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 only one element being applied
    • C23C8/48—Nitriding
    • C23C8/50—Nitriding of ferrous surfaces

Definitions

  • This invention relates to a process for case hardening steel and, particularly, to a process for riitriding, carbonitrid-. ing, and carburizing of steel parts.
  • a process for forming a hardened case on a ferrous metal including the steps of providing a fused chemical salt bath consisting essentially of a first material selected from the group consisting of alkali halides, or alkaline earth halides, or mixtures thereof, and a second material selected from the group consisting of alkali oxides, alkaline earth oxides, alkali carbonates, alkaline earth carbonates, or mixtures thereof; maintaining said fused chemical salt bath at a temperature from about 540°C.
  • the single figure is a graphical representation of the optimum rates of addition of urea to the fused bath as a function of temperature and size of the load being treated.
  • the graph is intended as a rough guideline for most low carbon, low alloy steel treatment.
  • a method and composition which allow one to selectively nitride, carbonitride, or carburize a steel workpiece to provide the desired case thereon.
  • the method employs a fused, nonactive chemical salt bath to which is added an organic material which will form certain carbon and nitrogen compounds, said compounds having the ability to add carbon, nitrogen, or both to a steel surface immersed in the bath.
  • nonactive bath means a bath which itself neither generates nor contains “active” compounds.
  • Active compounds are those which, upon giving up carbon and/or nitrogen to the steel to form a case thereon, are transformed into nonactive compounds.
  • a nitrided case is defined herein to mean a case comprised essentially of iron and nitrogen, usually in the form of iron nitrides.
  • a carburized case is defined to mean a case comprised essentially of iron and carbon, and a carbonitrided case is defined as one which contains iron with significant amounts of both carbon and nitrogen.
  • the organic material usually is added only so long as there is work in the bath to be treated. After the treatment is finished, the addition of material may be ceased. The. result is that carbon and nitrogen-containing compounds are no longer generated, and residual active compounds are slowly destroyed by thermal decomposition, or by reaction with the walls of a metallic salt pot if such type of pot is used. Hence, the bath when not in use becomes nonactive. Thus, there is no need to maintain a high concentration of toxic materials such as cyanides and cyanates.
  • the nonactive chemical salt bath may be any fused alkali halide or alkaline earth halide, or combination of such halides, with from about 1 to about 20 weight percent added thereto of an alkali oxide or alkaline earth oxide or carbonate, or mixtures of such carbonates and oxides.
  • a preferable composition is from 64-68 weight percent calcium chloride, CaC12; 30-32 weight percent sodium chloride, NaCl; and 1-5 weight percent calcium carbonate, CaC0 3 .
  • the melting point of this composition is about 510°C. (950°F.).
  • the organic material for addition to the bath may be urea or dicyanodiamide. It may also be any of the pyrolysis/condensation products of urea or dicyanodiamide, such as melamine, melem, melam, and melon. It may also be any combination of the aforesaid organic materials.
  • the nonactive bath is first brought to the desired operating temperature, chosen from within the range of about 540°C. (1000°F.) to about 950°C. (1750°F.). The selection of the temperature will be discussed presently.
  • the organic material is then added to the bath, preferably slowly, continuously, and at a constant rate.
  • the amount of cyanamide formed is limited by the initial concentration of oxide/carbonate. Thus, if the initial oxide/carbonate amount was 3 weight percent, the maximum amount of cyanamide that can form in the bath is also 3 weight percent. Excess organic material is thermally decomposed and is lost.
  • the workpieces to be treated may be immersed in the salt bath either before or after addition of organic material has begun.
  • the pieces should be clean and dry.
  • the pieces are maintained in the bath for virtually any amount of time, depending upon the case thickness required.
  • the general reaction at a steel surface in the bath is as follows: oxide (O -2 ) and/or carbonate (CO 3 -2 ) ions + carbon (C) and/or nitrogen (N) for diffusion into steel.
  • Agitation of the bath during operation is desirable, in order that active compounds may be evenly dispersed to the entire load. Agitation is usually accomplished by means of either a stirring mechanism, or by bubbling a gas such as air or nitrogen through the bath.
  • the bath is free of alkali and/or alkaline earth metal cyanide or alkali and/or alkaline earth metal cyanate salts, and in fact all cyanides and cyanates before the process, during the process, and after the process is completed.
  • the optimum rates of addition of urea for temperatures between 590°C. (11000F.) and 950°C. (1750°F.) are shown in graphic form in the figure. As can be seen in the figure, the size of the load being treated has been divided somewhat arbitrarily into three categories; light loads (2 square inches of load surface area per lb. of salt); medium loads (5 sq. inches of surface area of load per lb. of salt); and heavy loads (8 sq. inches of surface area of load per lb. of salt).
  • the rates of addition for each type of load are graphed as the addition rate in % per hour based on bath weight as a function of temperature and varies from about 0.2% to about 4%. Of course, different ' load surface areas can be extrapolated from those graphed. As noted, the addition rates are based on urea being added, but slight experimentation will determine the optimum rate for other materials.
  • the workpieces are withdrawn from the bath and then either slow cooled or quenched in an appropriate quenching medium, again depending upon the case characteristics desired.
  • the addition of organic material, having been continued during the immersion of the pieces, may now be ceased. If desired, organic material addition may be terminated before the pieces are withdrawn, to allow the residual active compounds and the thermal diffusion effects to complete the case formation.
  • the type of case formed on the steel is primarily dependent upon the temperature at which the bath is maintained, the type of quench applied, and the composition of the base steel.
  • the case formed at or below 590°C. (1100°F.) is essentially a nitride case, i.e., a case containing essentially iron and nitrogen.
  • the outermost portion of the case usually consists of iron nitrides E FeN, E Fe 3 N, and/or ⁇ 1 Fe 4 N.
  • the fast quench forms martensitic/bainitic structures only in the region of the case; the core material is essentially unaffected.
  • a high organic material feed rate will produce a case type consisting of an outer layer of essentially iron nitride, under which exists an austenitic or pearlitic zone.
  • the case consists of essentially iron and carbon; this is the "carburized" case. Again, this case is usually fast quenched to produce a martensitic or bainitic structure.

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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)
EP19810300922 1981-03-05 1981-03-05 Verfahren zum Einsatzhärten von Stahl Expired EP0059803B1 (de)

Priority Applications (2)

Application Number Priority Date Filing Date Title
DE8181300922T DE3173690D1 (en) 1981-03-05 1981-03-05 A process for case hardening steel
EP19810300922 EP0059803B1 (de) 1981-03-05 1981-03-05 Verfahren zum Einsatzhärten von Stahl

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
EP19810300922 EP0059803B1 (de) 1981-03-05 1981-03-05 Verfahren zum Einsatzhärten von Stahl

Publications (2)

Publication Number Publication Date
EP0059803A1 true EP0059803A1 (de) 1982-09-15
EP0059803B1 EP0059803B1 (de) 1986-02-05

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DE (1) DE3173690D1 (de)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2483962A1 (fr) * 1980-06-10 1981-12-11 Haertol Werk Agent de nitruration en bain de sel exempt de cyanure et de cyanate
JP2018083964A (ja) * 2016-11-22 2018-05-31 住友電気工業株式会社 窒化鉄材及び窒化鉄材の製造方法
CN114086109A (zh) * 2021-11-22 2022-02-25 湖南能岦新材料科技有限公司 一种新型环保防腐高效bsb金属表面处理方法

Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1772866A (en) * 1927-07-02 1930-08-12 Hirsch Marx Treatment of iron and steel
FR744050A (de) * 1931-12-09 1933-04-10
US2049806A (en) * 1933-03-10 1936-08-04 Du Pont Carburization of ferrous metals
DE800132C (de) * 1948-10-02 1950-09-22 Degussa Schmelzbad zum Aufkohlen und zur entkohlungsfreien Waermebehandlung von Staehlen
US2541085A (en) * 1948-09-14 1951-02-13 American Cyanamid Co Carburizing bath
US2801154A (en) * 1953-12-31 1957-07-30 Ethyl Corp Preparation of metal cyanates
US3303063A (en) * 1964-06-15 1967-02-07 Gen Motors Corp Liquid nitriding process using urea
DE2310250A1 (de) * 1973-03-01 1974-09-05 Hermann Dr Behncke Anwendung ungiftiger nitrile, bzw. cyanide in der stahlhaertung

Patent Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1772866A (en) * 1927-07-02 1930-08-12 Hirsch Marx Treatment of iron and steel
FR744050A (de) * 1931-12-09 1933-04-10
US2049806A (en) * 1933-03-10 1936-08-04 Du Pont Carburization of ferrous metals
US2541085A (en) * 1948-09-14 1951-02-13 American Cyanamid Co Carburizing bath
DE800132C (de) * 1948-10-02 1950-09-22 Degussa Schmelzbad zum Aufkohlen und zur entkohlungsfreien Waermebehandlung von Staehlen
US2801154A (en) * 1953-12-31 1957-07-30 Ethyl Corp Preparation of metal cyanates
US3303063A (en) * 1964-06-15 1967-02-07 Gen Motors Corp Liquid nitriding process using urea
DE2310250A1 (de) * 1973-03-01 1974-09-05 Hermann Dr Behncke Anwendung ungiftiger nitrile, bzw. cyanide in der stahlhaertung

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2483962A1 (fr) * 1980-06-10 1981-12-11 Haertol Werk Agent de nitruration en bain de sel exempt de cyanure et de cyanate
JP2018083964A (ja) * 2016-11-22 2018-05-31 住友電気工業株式会社 窒化鉄材及び窒化鉄材の製造方法
CN114086109A (zh) * 2021-11-22 2022-02-25 湖南能岦新材料科技有限公司 一种新型环保防腐高效bsb金属表面处理方法

Also Published As

Publication number Publication date
DE3173690D1 (en) 1986-03-20
EP0059803B1 (de) 1986-02-05

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