WO2008043062A1 - Procédé de durcissement duplex et articles ainsi fabriqués - Google Patents

Procédé de durcissement duplex et articles ainsi fabriqués Download PDF

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Publication number
WO2008043062A1
WO2008043062A1 PCT/US2007/080549 US2007080549W WO2008043062A1 WO 2008043062 A1 WO2008043062 A1 WO 2008043062A1 US 2007080549 W US2007080549 W US 2007080549W WO 2008043062 A1 WO2008043062 A1 WO 2008043062A1
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WO
WIPO (PCT)
Prior art keywords
boost
steel
periods
workpiece
nitriding
Prior art date
Application number
PCT/US2007/080549
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English (en)
Inventor
David L. Milam
Carl Ribaudo
James L. Maloney, Iii
Robert Hoff
Elizabeth Cooke
Original Assignee
The Timken Company
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
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Publication of WO2008043062A1 publication Critical patent/WO2008043062A1/fr

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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
    • 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
    • C23C8/06—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 gases
    • C23C8/36—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 gases using ionised gases, e.g. ionitriding
    • C23C8/38—Treatment of ferrous surfaces
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
    • C21D1/06—Surface hardening
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
    • C21D1/74—Methods of treatment in inert gas, controlled atmosphere, vacuum or pulverulent material
    • C21D1/76—Adjusting the composition of the atmosphere
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
    • C21D1/78—Combined heat-treatments not provided for above
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D9/00—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
    • C21D9/32—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for gear wheels, worm wheels, or the like
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D9/00—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
    • C21D9/40—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for rings; for bearing races
    • 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
    • C23C8/06—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 gases
    • C23C8/08—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 gases only one element being applied
    • C23C8/24—Nitriding
    • C23C8/26—Nitriding of ferrous surfaces

Definitions

  • the present invention relates to a new process for duplex hardening of steels and articles made by this process. Description of Related Art
  • Duplex hardening of gears and bearing components is known in the art.
  • the duplex hardening process is aptly named since it implies that the material is hardened by two methods.
  • the material is first hardened by either carburization and quenching of a low carbon alloy steel grade (such as AMS 6278 steel) or by quenching a homogeneous high carbon alloy steel (such as AMS 6491 steel).
  • a low carbon alloy steel grade such as AMS 6278 steel
  • a homogeneous high carbon alloy steel such as AMS 6491 steel
  • Either material is further hardened by the addition of nitrogen to the surface.
  • the purpose of this second hardening treatment is to increase the strength and hardness of the surface and near-surface region.
  • the increased hardness of the material resists indentation by hard debris particles, which is particularly beneficial in bearings and gears.
  • duplex hardening is used only for more highly alloyed, higher performance bearings and gears such as those used in aerospace applications.
  • the earlier work involving duplex hardening showed no concern for the phenomenon of Inter Granular Network ("IGN”) formation. More recently, there have been efforts to prevent formation of these networks by utilizing short process times and shallow hardening depth, as well as low nitriding potentials.
  • IGN Inter Granular Network
  • intragranular carbides dissolve and liberate their respective carbon atoms. The liberated carbon then diffuses further inward where it combines with iron at the grain boundaries to form cementite, Fe 3 C (see Figure 1).
  • U.S. Patent No. 6,966,954 to Rhoads et al. discloses a method for subjecting bearing material to a constant partial pressure of nitrogen.
  • the steel workpieces are subjected to a lengthy, constant low nitriding potential atmosphere. This method is relatively easy to practice provided that precise control of gas flows is possible. It is important to keep the nitrogen concentration in the workpieces near the surface below 2.0% by weight because a deleterious IGN will form if the nitrogen concentration rises above approximately 2.0%.
  • the workpiece is subjected to this constant atmosphere for up to 80 hours. The results of this process are not consistently acceptable because slight variations in furnace temperature and a variation in the amount of nitrogen input into the process can significantly influence the results of the process.
  • the present invention is directed to a process for hardening steel workpieces and to articles made from those workpieces using that process such as bearing rings, rolling elements, gears, cams, splines and lifters, comprising the steps of subjecting a workpiece steel to at least two sequential process segments wherein each process segment consists of subjecting the workpiece to a Boost period in an atmosphere containing active nitrogen, then subjecting the workpiece to a Diffuse period in an atmosphere free of active nitrogen to provide a desired target nitrided case depth in the steel workpiece in approximately 30% less time than in the prior art duplex hardening process with no deleterious intergranular network formation at the case surface.
  • FIG. 1 is a photomicrograph showing the presence of cementite lying in grain boundaries after nitriding
  • Fig. 2 is a graph comparing the nitrogen contents in the surface nitrided case of a conventionally processed workpiece and one processed according to the present invention
  • Fig. 3 is a photomicrograph of a steel nitrided by a conventional process showing the presence of a deleterious IGN extending to the workpiece surface
  • Fig. 4 is a photomicrograph of a steel workpiece nitrided by the process of the present invention showing non-deleterious IGN spaced well below the surface of the workpiece.
  • the present invention differs from the prior art process described above in that the workpiece is not subjected to a lengthy (up to 80 hours) constant, low active nitrogen (approximately 1%) source.
  • the nitriding process of the present invention is of the Boost/Diffuse (BD) type.
  • BD Boost/Diffuse
  • a Diffuse period is conducted upon the termination of the Boost period. No additional nitrogen is added to the steel during the Diffuse period of the process. Due to gradients in chemical potential and concentration, the nitrogen existing inside the steel workpiece near the surface diffuses deeper into the steel during the Diffuse period. This diffusion of nitrogen away from the surface causes the concentration of nitrogen in the near-surface region to decrease.
  • a “process segment" according to the present invention consists of one Boost period and one Diffuse period.
  • a second process segment may follow the first process segment and begins with a second Boost period followed by a second Diffuse period.
  • Boost period a source of active nitrogen is input into the process, additional nitrogen is deposited on the surface, and this nitrogen diffuses into the steel.
  • concentration of nitrogen in the near-surface region begins to increase after having declined during the aforementioned, first Diffuse period.
  • Boost period a second Diffuse period is then conducted during which no active nitrogen is made available to the steel workpiece.
  • the second process segment has been completed.
  • the process cycle according to the present invention consists of two or more process segments comprising alternating periods of Boost and Diffuse.
  • a consequence of at least two sequential process segments, each consisting of one Boost period and one Diffuse period, provides that a process segment always ends with a Diffuse period. This consequence allows for the nitrogen concentration in the near-surface region of the workpiece to be relatively lower than that provided in the constant low nitriding potential process of the prior art.
  • the vessel When plasma nitriding is used in the Boost period of the present process, the vessel is evacuated for the Diffuse period leaving no denitriding or decarburizing species in the vessel.
  • gas nitriding is used in the Boost period, the vessel is then filled with an inert gas such as argon for the Diffuse period which does not react with the steel workpiece surface; thus, no denitriding is possible.
  • the BD process of the present invention produces less IGN in the steel workpiece than the prior art duplex hardening processes.
  • the present process creates a unique nitrogen concentration profile.
  • concentration profiles of the BD process of the invention and the known low constant nitriding potential process of the prior art are depicted schematically in Figure 2.
  • the conventional process produces a nitrogen concentration curve that is mostly above that of the
  • FIG. 3 Intersections of IGN with the surface as shown in Figure 3 are potential sites for the formation of cracks on a micro crack scale. Thus, the small amounts of IGN that may be created within the present BD process that are spaced from the surface will not contribute to spall formation.
  • Figure 4 is an exemplary microstracture from a sample prepared using the BD process. Comparison of Figures 3 and 4 shows the relative positions of IGN in the two processes. Figure 4 clearly demonstrates the superiority of the present process with respect to the non-existence of deleterious IGN at the surface of the steel workpiece.
  • any IGN that may form in the steel during the present process consists of short lengths situated deep within the nitrided case. Thus, the small amounts of IGN, if present, do not intersect the surface and are not deleterious to spall formation.
  • the BD process cycle of the present invention is approximately 30% shorter than the low constant nitriding potential duplex hardening process, thus providing obvious economic benefits.
  • the candidate steel would have achieved prior to nitriding a minimum hardness of about 60 HRC from the surface to a depth based upon the component dimensions and application. These levels of hardness can extend throughout the component depending upon the application requirements and the steel that is selected. This hardness can be achieved by either carburizing followed by quenching and tempering or by quenching and tempering alone. These alloys must also have sufficient tempering resistance during nitriding so that the hardness of the material meets application requirements at all depths after nitriding is completed. The tempering resistance is achieved by having the steel contain sufficient amounts of alloying elements such as Cr, Mo 5 Si 5 Ni, Co, Mn, and/or V or combinations thereof.
  • the steels will also contain alloying elements that form nitrides such as Cr, Mo, V, Nb, and/or Al or combinations thereof.
  • carburizing steels that are possible candidates include AMS 6278 (M50n.il), CBS 223, AMS 5930 (Pyrowear 675), AMS 5932 (CSS42L), AMS 6749 (BG42), CBS 1000, and BS S132.
  • Examples of steels that are candidates for quenching and tempering alone prior to nitriding are AMS 6491 (M50), M2, AMS 5630 (440C), ASTM Tl 5, and AMS 5898 (Cronidur 30).
  • the workpieces being nitrided are steel components that otherwise are in a completed or nearly completed form.
  • the steel used in these components will have been melted and worked into raw material forms such as billets, bars, rods or seamless tubes.
  • Some applications would require the use of vacuum melting and refining techniques and may require multiple melting processes.
  • Typical working methods would include one or more of the following processes: rolling, forging, piercing and ring rolling.
  • the raw material would be cut into pieces that are directly machined or forged then machined into blanks corresponding to the rough geometry of the final components.
  • the blank can be made by the consolidation of steel powders using such techniques as hot or cold isostatic pressing (HIP or CIP).
  • the HIP or CIP may be preformed either directly to produce a blank or a preform such as a solid cylinder which is then worked and/or machined to blank dimensions.
  • Blanks formed by any of these methods are heat treated either by a sequence of carburizing, quenching, and tempering or by a sequence of austenitizing in a non-carburizing atmosphere, quenching, and tempering.
  • the quenching and tempering could either be performed by batch austenitizing and quenching or by surface hardening using techniques such as induction, laser or electron beam. Gaseous, pack, plasma or vacuum carburizing may be used.
  • Quenching media may include air or other gas(es) or iiquid(s).
  • the quenchant may be preformed either directly to produce a blank or a preform such as a solid cylinder which is then worked and/or machined to blank dimensions.
  • Blanks formed by any of these methods are heat treated either by a sequence of carburizing, quenching, and tempering
  • ⁇ W0300223.I ⁇ -6- be still or flowing or agitated.
  • Carburized blanks may be rehardened for optimal properties. Multiple tempers may be performed on either carburized or direct quenched product.
  • controlled amounts of material are removed from the blanks to dimensions that are near or at the final dimensions of the component.
  • Material removal methods may include grinding, lapping, hardturning and/or honing.
  • the nitriding process of the present invention is then carried out using gaseous, plasma, or salt bath techniques. Nitriding may be either the last manufacturing step carried out or can be followed by finishing processes using techniques such as grinding, lapping, hardturning, honing and/or superfinishing to achieve final dimensions and surface texture.
  • Some areas of the workpiece may be prevented from nitriding due to fixturing or deliberate masking. Examples of the workpieces would be bearing rings, rolling elements and gears.
  • Nitriding using a pulsed plasma hot-wall dc furnace has been successfully used by the inventors as described below. This type of furnace has an insulated external shell with heating elements so the workpiece temperature is maintained without relying on the heating produced by plasma generation. Therefore, the ion current during the Boost period can be selected as a variable independent of the workpiece temperature. Even more significantly, the workpiece temperature can be maintained during the Diffuse period when no plasma is being generated.
  • controlled gas nitriding is another means of performing the BD process.
  • the nitrogen potential of the atmosphere within the furnace is determined automatically throughout the nitriding process.
  • the measured nitrogen potential is compared to the setpoint value by the control system.
  • the control system then adjusts the composition of the incoming gas mixture as needed to achieve the desired nitrogen potential.
  • the required number of Boost/Diffuse process segments can be programmed into the controller for automatic operation.
  • Selection of the appropriate values for the key parameters for the nitriding process such as workpiece temperature, total nitriding time, percentage of time in Boost and active nitrogen potential during Boost depend upon the steel type, prior heat treatment, part geometry and material property requirements.
  • the nitriding process parameters needed to produce the required properties in the workpiece are interdependent within ranges.
  • the workpiece temperature is typically selected to minimize process time while preventing overtempering or softening.
  • the workpiece temperature is expected to be in the range of
  • the total process time (Boost + Diffuse) is expected to be in the range of 40 to 80 hours.
  • the Boost periods are expected to last about 2 to 20 hours while Diffuse periods may last from about 2 to 28 hours.
  • the Boost periods may be of equal length or vary from one process segment to the next.
  • the Diffuse periods may be of equal length or vary from one process segment to the next.
  • the percentage of total nitriding time spent in Boost periods is expected to range from 20 to 70% of the total process time. It is expected that the atmosphere would contain about 5 to 25 volume % active nitrogen during Boost periods.
  • the amount of active nitrogen during each Boost period may be the same or could be varied.
  • Samples of quenched and tempered AMS 6491 steel and of carburized quenched and tempered AMS 6278 steel were pulse plasma nitrided using the BD process.
  • the samples were ground after tempering and before nitriding.
  • the total process time was about 20 to 60 hours. Up to 6 process segments were used.
  • the preferred nitrogen concentration in the incoming gas mixture during the Boost periods was between about 10 to 20 volume %.
  • the percentage of time spent in Boost was about 30 to 65% of the total process time.
  • the nitriding temperature was between about 440 0 C and 524 0 C during both the Boost and Diffuse periods.
  • AMS 6491 and AMS 6278 steel were observed for a nitriding temperature of about 500 0 C and a total process time of about 60 hours with 6 process segments.
  • the nitrogen concentration was between about 10 to 20 volume % in the incoming gas mixture during the Boost periods and the percentage of time in the Boost cycle was between about 30 to 50% of the total process time.
  • the AMS 6491 samples prepared within this process range produced near surface hardness values equivalent to about at least 68 HRC compared to a pre-nitriding hardness of about 64 HRC while the AMS 6278 samples achieved near surface hardness values equivalent from about 65 HRC to at least 68 HRC compared to a pre-nitriding hardness of approximately 62 HRC.
  • the depth to a hardness approximately equivalent to 67 HRC extended to depths of about 0.09 to 0.21 mm.
  • the AMS 6278 samples exhibited a hardness approximately equivalent to 65 HRC to depths of about OJO to 0.20 mm.
  • the concentration of IGN in samples of both materials observed using optical microscopy was much less than
  • AMS 6491 and AMS 6278 steel were observed for a gas nitriding temperature of about 500 0 C and a total BD process time of about 60 hours with 6 process segments.
  • the nitrogen potential, K N in the incoming gas mixture during Boost was between about 1.1 and 6, and the percentage of time in Boost was between about 20 to 30%.
  • the AMS 6491 samples prepared within this process range produced near surface hardness values equivalent to about at least 68 HRC compared to a pre-nitriding hardness of about 62 HRC while the AMS 6278 samples achieved near surface hardness values equivalent from about 65 HRC to at least 68 HRC compared to a pre-nitriding hardness of approximately 62 HRC.
  • the depth to a hardness approximately equivalent to 67 HRC extended to depths of about 0.08 to 0.21 mm.
  • AMS 6278 samples exhibited a hardness approximately equivalent to 65 HRCD to depths of about 0.08 to 0.23 mm.
  • concentration of IGN in samples of both materials observed using optical microscopy was much less than that observed in Figure 3 and was typically located away from the surface as shown in Figure 4. In some samples, no IGN was observed at all using optical microscopy.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Mechanical Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Solid-Phase Diffusion Into Metallic Material Surfaces (AREA)
  • Heat Treatment Of Articles (AREA)

Abstract

L'invention concerne un procédé de durcissement de pièces en acier et des articles ainsi fabriqués, tels que des bagues de roulements, des éléments roulants, des roues dentées, des cames, des cannelures et des poussoirs, ledit procédé comprenant les étapes consistant à soumettre une pièce en acier à au moins deux segments de procédé séquentiels, chacun desdits segments de procédé consistant à soumettre la pièce à une période d'amplification (dite « Boost ») sous une atmosphère contenant de l'azote actif, puis à soumettre la pièce à une période de diffusion (dite « Diffuse ») sous une atmosphère dépourvue d'azote actif, afin de produire une profondeur de nitruration cible souhaitée dans la pièce en acier en moins de temps qu'avec le procédé de durcissement duplex de l'art antérieur, sans formation de réseaux intergranulaires néfastes dans la région de surface.
PCT/US2007/080549 2006-10-05 2007-10-05 Procédé de durcissement duplex et articles ainsi fabriqués WO2008043062A1 (fr)

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US84972606P 2006-10-05 2006-10-05
US60/849,726 2006-10-05

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Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2013173009A1 (fr) 2012-05-17 2013-11-21 United Technologies Corporation Procédé de fabrication pour des éléments de roulement de paliers aérospatiaux
CN104032115A (zh) * 2014-06-11 2014-09-10 杭州前进齿轮箱集团股份有限公司 一种减小二级齿圈氮化变形的热处理方法
DE102015104583A1 (de) 2015-03-26 2016-09-29 Georg-August-Universität Göttingen Stiftung Öffentlichen Rechts, Universitätsmedizin Implantierbare Vorrichtung zum Ausbilden einer permanenten Hautdurchführung
CN110359008A (zh) * 2019-08-29 2019-10-22 安徽聚力石油钻采设备科技有限公司 一种渗碳与qpq处理的复合工艺及其应用
DE102020122734A1 (de) 2020-08-31 2022-03-03 Rolls-Royce Deutschland Ltd & Co Kg Wärmebehandlungsverfahren für sekundärhärtende Stähle
US11491541B2 (en) 2019-05-31 2022-11-08 Apollo Machine & Welding Ltd. Hybrid process for enhanced surface hardening

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US4046601A (en) * 1976-06-01 1977-09-06 Armco Steel Corporation Method of nitride-strengthening low carbon steel articles
DE4033706A1 (de) * 1990-10-24 1991-02-21 Hans Prof Dr Ing Berns Einsatzhaerten mit stickstoff zur verbesserung des korrosionswiderstandes martensitischer nichtrostender staehle
WO1998012361A1 (fr) * 1996-09-18 1998-03-26 The Timken Company Element de palier en acier inoxydable et cemente et son procede de fabrication
US5833918A (en) * 1993-08-27 1998-11-10 Hughes Electronics Corporation Heat treatment by plasma electron heating and solid/gas jet cooling
US6966954B2 (en) * 2002-10-24 2005-11-22 General Electric Comany Spall propagation properties of case-hardened M50 and M50NiL bearings
DE102004053935A1 (de) * 2004-11-09 2006-05-11 Fag Kugelfischer Ag & Co. Ohg Verfahren zur Wärmebehandlung eines Bauteils aus einem durchhärtenden warmfesten Stahl und Bauteil aus einem durchhärtenden warmfesten Stahl

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4046601A (en) * 1976-06-01 1977-09-06 Armco Steel Corporation Method of nitride-strengthening low carbon steel articles
DE4033706A1 (de) * 1990-10-24 1991-02-21 Hans Prof Dr Ing Berns Einsatzhaerten mit stickstoff zur verbesserung des korrosionswiderstandes martensitischer nichtrostender staehle
US5833918A (en) * 1993-08-27 1998-11-10 Hughes Electronics Corporation Heat treatment by plasma electron heating and solid/gas jet cooling
WO1998012361A1 (fr) * 1996-09-18 1998-03-26 The Timken Company Element de palier en acier inoxydable et cemente et son procede de fabrication
US6966954B2 (en) * 2002-10-24 2005-11-22 General Electric Comany Spall propagation properties of case-hardened M50 and M50NiL bearings
DE102004053935A1 (de) * 2004-11-09 2006-05-11 Fag Kugelfischer Ag & Co. Ohg Verfahren zur Wärmebehandlung eines Bauteils aus einem durchhärtenden warmfesten Stahl und Bauteil aus einem durchhärtenden warmfesten Stahl

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2013173009A1 (fr) 2012-05-17 2013-11-21 United Technologies Corporation Procédé de fabrication pour des éléments de roulement de paliers aérospatiaux
EP2849920A4 (fr) * 2012-05-17 2016-06-01 United Technologies Corp Procédé de fabrication pour des éléments de roulement de paliers aérospatiaux
US9732394B2 (en) 2012-05-17 2017-08-15 United Technologies Corporation Manufacturing process for aerospace bearing rolling elements
CN104032115A (zh) * 2014-06-11 2014-09-10 杭州前进齿轮箱集团股份有限公司 一种减小二级齿圈氮化变形的热处理方法
DE102015104583A1 (de) 2015-03-26 2016-09-29 Georg-August-Universität Göttingen Stiftung Öffentlichen Rechts, Universitätsmedizin Implantierbare Vorrichtung zum Ausbilden einer permanenten Hautdurchführung
US11491541B2 (en) 2019-05-31 2022-11-08 Apollo Machine & Welding Ltd. Hybrid process for enhanced surface hardening
CN110359008A (zh) * 2019-08-29 2019-10-22 安徽聚力石油钻采设备科技有限公司 一种渗碳与qpq处理的复合工艺及其应用
DE102020122734A1 (de) 2020-08-31 2022-03-03 Rolls-Royce Deutschland Ltd & Co Kg Wärmebehandlungsverfahren für sekundärhärtende Stähle

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