US3560271A - Nitriding method - Google Patents

Nitriding method Download PDF

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US3560271A
US3560271A US730216A US3560271DA US3560271A US 3560271 A US3560271 A US 3560271A US 730216 A US730216 A US 730216A US 3560271D A US3560271D A US 3560271DA US 3560271 A US3560271 A US 3560271A
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work piece
cooling
pressure vessel
nitriding
die
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Hans Heinen
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Otto Fuchs KG
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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
    • 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
    • C21D1/773—Methods of treatment in inert gas, controlled atmosphere, vacuum or pulverulent material under reduced pressure or vacuum

Definitions

  • the present invention is concerned with the nitriding of metallic work pieces, particularly work pieces of highly alloyed metals and primarily work piecesof alloyed steel, whereby the steel may be alloyed, for instance, with one or more of the metals nickel, manganese, chromium, molybdenum, vanadium and tungsten.
  • Such alloyed steels are used for tools and also for machine parts which must withstand sliding contact, such as crankshafts, pistons and cylinders in which pistons are to move. Such products are progressively more sensitive with respect to crack formation the higher the proportion of alloy constituents therein. For this reason, as will be discussed further below, the advantages of the present invention are particularly significant with respect to tools and work pieces of highly alloyed metals.
  • the invention is not necessary limited to the treatment of highly alloyed steel.
  • the present invention is also highly advantageous in connection with the nitriding of stellite, i.e. an alloy of predominantly chromium and cobalt.
  • Nitriding may be carried out in various manners known per se in the art and the present invention is particularly concerned with modifications of the nitriding, particularly the subsequent cooling of the nitrided work piece, in such cases in which the nitriding is carried out in molten nitriding salt mixtures, for instance by the method known as the Tenifer method of the firm Degussa, Germany. This method comprises melting a mixture of nitrogen-containing salts and immersing the work pieces which are to be nitrided into the molten salt bath.
  • This and other conventional nitriding methods permit excellent hardening of alloyed metals, particularly highly alloyed steel, whereby the work pieces also may be formed of sintered metals. Contrary to the conventional cementing methods, such nitriding gives particularly high hardness values; however, the depth or penetration of the thus-formed nitride layer is rather limited, especially in the case of highly alloyed metals even if the nitriding is carried out for prolonged periods of time. The depth of nitriding may reach values of barely hundred microns; however, this depth referes to the depth of diffusion of nitrogen and not to the depth to which actually a nitrogen-containing metal compound such as Fe N is formed.
  • This compound zone generally has a thickness of only about l020 microns.
  • the exact composition of the compound zone is of no concern here, but it is important to note that there is formed by nitriding a relatively thin compound zone, much thinner than the zone of diffusion, which compound zone is mainly responsible for the hardness of the treated work piece and may consist for instance of a complex compound of cementite and nitride such as Fe C-Fe N. At a greater depth, i.e. within the remaining diffusion zone, nitrogen atoms will be found but not the alloy or compound Fe N.
  • the abovedescribed compound zone is so very thin, i.e. generally has a thickness of only to up to about 20 microns.
  • the problem of cooling the freshly nitrided work pieces which in liquid nitriding salt solutions generally were heated to a temperature of somewhat below 600 C., such as 570 C., represents a very serious problem.
  • the nitrided work pieces are highly sensitive against surface corrosion by reaction with oxygen and against the formation of tension cracks. Particularly if the hard nitrided compound zone at the surface of the work piece is combined with complicated configurations, heat tensions occur as soon as the work piece is taken from the molten salt bath and subjected to cooling.
  • metallic work pieces are nitrided by subjecting the work piece to nitriding at a nitriding temperature which is significantly above about 500 C., generally somewhat below 600 C. and frequency about 570 C.
  • the thus-nitrided hot work piece is then conveyed through the ambient atmosphere into an evacuatable zone at such speed that during passage through the ambient atmosphere the temperature of the hot nitrided work piece will drop only slightly, generally less than about C. and preferably not below about 500 C.
  • the latter is evacuated to a residual pressure of up to about 20 mm. of mercury, preferably to between 2 and 20 mm.
  • mercury or up to 2 mm. mercury, and the still hot Work piece, which has been introduced into the evacuatable zone at a temperature preferably above or not lower than about 500 C., will then be allowed to cool by heat radiation while located in the thus-evacuated zone.
  • the metallic work piece may be and frequently is formed of higfhly alloyed steel and the cooling in the evacuated zone may be continued until the work piece has reached room temperature, but generally it will sufiice to continue cooling by heat radiation of the work piece located in the evacuated zone until the temperature of the work piece has been lowered to about 0, since at a temperature of about 150 C. practically no reaction between the surface layer of the work piece and the oxygen of ambient air would occur.
  • the evacuated zone preferably is represented by the interior of a pressure vessel into which the work piece is introduced, whereupon the pressure vessel is closed and evacuated.
  • the heat withdrawal from the hot work piece takes place by heat radiation therefrom while the work piece is located in the evacuated interior of the pressure vessel.
  • the present invention is also concerned with an arrangement for carrying out the above described method which arrangement comprises a nitriding furnace or vessel in which a molten bath of nitriding salts is maintained, the above-described pressure vessel, suitable conduits and a vacuum pump or the like for evacuating the pressure vessel, conveying apparatus for lifting the nitrided hot work piece from the molten salt bath and introducing it into the pressure vessel, and electronic control arrangements for actuating the conveying arrangement, the vacuum pump or the like, and possibly also for opening and closing the lid of the pressure vessel in accordance with a preset schedule which may be made dependent on readings of time and temperature.
  • nitriding bath or furnace may be used to its full capacity by successively feeding the hot nitrided work pieces into different ones of the series of pressure vessels arranged in the vicinity of the nitriding furnace.
  • the conveying of the hot nitrided work pieces to specific ones of the series of pressure vessels also may be electronically controlled in a manner which, per se, will be apparent to those skilled in the art.
  • FIG. 1 is a schematic, elevational, perspective view of a complete nitriding arrangement in accordance with the present invention.
  • FIG. 24 are illustrations, on a scale larger than that of FIG. 1, of specific work pieces which may be advantageously nitrided in accordance with the present invention.
  • the second concept which is to be considered in connection with the present invention, is concerned with the formation of undesirable surface or corrosion layers.
  • the formation of surface layers takes place not so much at the point or moment of withdrawal of the work piece from the molten salt bath and its exposure to the ambient atmosphere but only somewhat later, namely after the oxygen of the air had time to diffuse through the salt layer adhering to the surface of the work piece and thus to come into direct contact with the metal surface of the work piece. It has been found that harmful surface layers are formed by the effect of contact with the ambient atmosphere only after the work piece had been removed from the molten salt bath for a certain length of time.
  • the work pieces have to be conveyed from the hot salt bath into the pressure vessel. It is desired to carry out this conveying as quickly as possible. However, no harm is done if during such conveying the work piece is cooled by up to about C. At the beginning of the conveying, the surface of the work piece is still covered by salt and, consequently, there is little risk of corrosion. Furthermore, obviously, at the beginning of the cooling no interior heat tensions will occur and this also is essential in accordance with the present invention.
  • the preferred temperature of molten salt nitriding baths is about 570 C. and it is desirable that the temperature of the work piece upon being introduced into the pressure vessel, i.e. immediately prior to evacuation of the pressure vessel, should still be somewhat above 500 C. To expose the work piece to the reduced pressure while the temperature thereof is still above 500 C. is particularly important in the case of complicated surface configurations.
  • a relatively simple work piece such as that shown in FIG. 2 and formed with a simple central bore instead of the rather involved configuration of the aperture indicated by reference numeral 21, possibly may be completely cooled while exposed to the ambient atmosphere.
  • the work piece would obtain a very rough surface due to the above-discussed chemical reactions which would take place upon such prolonged exposure during cooling to the influence of the oxygen of the ambient atmosphere and it would be most expensive and difiicult to subsequently convert such surface into the desired smooth surface.
  • the method of the present invention has been successfully carried out with respect to work pieces of greatly varying configurations and sizes.
  • the theoretically achievable advantages of the prohibitively expensive complete vacuum treatment i.e. vacuum treatment from the moment of withdrawal from the molten salt bath until cooling to a sufficiently low temperature
  • the method of the present invention lends itself excellently to substantial automation and electronic control whereas conventional methods of this type required substantial skilled labor for controlling the cooling process.
  • the work pieces will cool in the evacuated pressure vessel at a rate depending on the mass of the respective work piece whereas the shape of the work piece will be of relatively insignificant importance with respect to the cooling speed in accordance with the present invention. Thus, no special measures have to be taken in order to find out in any given case the most advantageous cooling rate which will avoid the formation of tension cracks.
  • the labor costs of the process are substantially lower than that of conventional processes since not only the nitriding in the molten salt bath, but also the cooling of the hardened work piece can be easily and reliably controlled in an automatic manner.
  • the easy control and possible automation of the process of the present invention also facilitates the scheduling of the process since work intermissions do no longer pose a problem. For instance, nitriding in the salt bath may be carried out up to the lunch break or up to the end of the working week and the cooling of the nitrided work pieces in the evacuated pressure vessels will then proceed during the break, week-end or the like, without requiring supervision.
  • While the present invention has been primarily described in connection with salt bath nitriding, it may also be used for the cooling of work pieces which were subjected to nitriding in a hot nitrogen atmosphere, whereby it will not be necessary to subject the nitrogen atmosphere to cooling.
  • an oil pump for evacuating the pressure vessel may be electronically controlled so as to stop operation when a desired minimum pressure of, for instance, 10 mm. mercury has been reached and, furthermore, one oil pump may serve for the evacuation of a plurality of pressure vessels.
  • the arrangement according to the present invention comprises a molten salt bath furnace 1 of conventional construction with the required auxiliary devices, a conveying device 2 and a pressure vessel 3 which is connected with an electrically operated vacuum pump 4.
  • Salt bath furnace 1 contains the molten salt mixture of alkali metal cyanate and alkali metal cyanide as required for carrying out nitriding in accordance with the Tenifer method.
  • the conveying device 2 includes a rail on which conveyor elements 5 move in a manner, i.e. at given time intervals, which may be electronically controlled. At the desired moment, work pieces 6 which had been immersed in furnace 1 are lifted with the help of servo motors by reducing the lengths of ropes 7, conveyed to pressure vessel 3 and introduced into the opened pressure vessel by lengthening rope 7.
  • a packing 12 is arranged, preferably formed of synthetic material commercially available under the name Teflon.
  • Teflon synthetic material commercially available under the name Teflon.
  • water cooling is installed in the side wall and/ or top of pressure vessel 3.
  • a temperature-sensing instrument 13 such as a thermometer, extends inwardly through the wall of pressure vessel 3 for the purpose of indicating the heat radiation therein which, in combination with the value for the residual pressure in the pressure vessel, will give a value which can be converted in a manner known per se to indicate the temperature of the work piece at any given time.
  • the weight of lid 10 and the pressure differential pressing the lid against the packing will serve for hermetic sealing and quick evacuation of the pressure vessel.
  • Conduit 14 connecting pump 4 with pressure vessel 3 may also communicate in per se known and not illus trated manner with several additional pressure vessels 3, whereby each of the pressure vessels will require only about two minutes for being evacuated down to a residual pressure of about 15 mm. mercury.
  • valve 14 which may be actuated in conventional magneto-electrical manner.
  • the pressure vessel 3 as illustrated has a capacity of 280 liters and pump 4 a capacity of 60 cubic meters per hour. When it is desired to evacuate the pressure vessel further, down to a residual pressure of about 2 mm. mercury, it is still possible with one pump 4 to operate six pressure vessels 3 without experiencing any difficulties.
  • thermometer 13 it is also possible to arrange thermometer 13 so that the same will be in direct contact with the work pieces within the pressure vessel. This may be accomplished by resiliently mounting thermometer 13 and will operate 10 satisfactorily since no quick movements of the work pieces will take place.
  • the periods of time during which work pieces should be allowed to cool by heat radiation while located in the evacuated pressure vessel will depend primarily on the weight or mass of the work piece and differ only very little with respect to the specific composition or shape thereof.
  • the work piece surface was found to have cooled down by heat radiation to about 150 C. and removal of the work piece from the pressure vessel and exposure of the work piece to the ambient atmosphere was then possible without any risk of damage to the surface of the work piece or of the formation of tension cracks.
  • the interior dimensions of the pressure vessel are of no consequence since heat radiation emanates radially from the work piece in all directions. True radiation will occur as long as the surroundings are colder than the work piece. For this reason, it is desirable to use pressure vessels which are provided, in their walls, with conventional water cooling. In this manner, the cooling period may be reduced to about one-fifth of that achieved without water cooling, particularly in cases in which the volume of the work piece or work pieces is substantial relative to the inner volume of the pressure vessel 3.
  • the temperature of the pressure vessel walls may be maintained by water cooling at about 20 C. so that initially a temperature differential of nearly 500 C. will exist between the temperature of the work piece and the temperature of the walls of the pressure vessel.
  • the work pieces 6 may consist, for instance, of sintered bodies of chromium-nickel steel or of highly alloyed tools of chromium steel or SS-steel or may be produced of other alloys in a great variety of sizes and shapes, and in all these cases, even after a useful life span of the nitrided work pieces of several months, no tension cracks were observed.
  • Particularly tools for warm working such as pressure casting molds for casting light or heavy metals can be treated successfully in accordance with the present invention, whereby due to the fault-free surfaces adherence between tool and mold will not take place.
  • nitrided work pieces may be improved, i.e. may be smoothed by being sub jected for a short period of time to dull lapping with silicon carbide having a particle size passing through 800 mesh. In this manner, the residual roughness can be reduced to between 1 and 2 microns. If in addition a polishing lapping with glass pearls is carried out, then the thus-treated surface obtains a silken smooth appearance, whereby only fractions of 1 micron of the surface layer are removed.
  • the extrusion opening 21 which is cut into die 20 serves for the extruding of aluminum rods which are used as building elements for windows, doors and the like.
  • the complicated crosssectional configuration of the extrusion opening frequently led to tension cracks and the surface of extruded aluminum alloy rods which were formed by extrusion through hardened dies of the type of die 20 frequently show fine longitudinal grooves, due to the fact that it is not possible to effectively work the hardened surfaces defining the extrusion orifice 21.
  • no tension cracks occurred the hardly accessible inner surface areas could be easily cleaned and were found then to be practically as smooth as prior to the hardening treatment.
  • FIG. 3 illustrates as a further example of a work piece a forging die which combined with a similar die serves for producing valve bodies and which also has been hardened in accordance with the present invention, in an arrangement as illustrated in FIG. 1.
  • the surfaces of the hardened work pieces were of the desired smoothness and particularly the critical areas 31 as well as areas 32 remained of accurate size even upon prolonged use under high stress no tension cracks occurred.
  • the cooling method of the present invention may also be used for the cooling of work pieces, especially work pieces formed of alloyed steel, which were subjected to nitriding in a hot nitrogen atmosphere and which thereafter may be introduced without substantial delay but in contact with the ambient atmosphere, into pressure vessel 3 and therein cooled, as described above, by heat radiation while maintained at a residual pressure of for instance 5 mm. mercury.
  • Example 1 An extrusion die as illustrated in FIG. 2 is to be nitrided.
  • the die consists of alloyed steel containing 0.4% carbon, 5% chromium, 1.5% molybdenum and 1% vanadium, and has a weight of 2.85 kg.
  • the diameter of the die is 13.8 cm. and the extrusion opening 21 is formed with an accuracy of :0115 mm.
  • the surface roughness of the inner faces of the extrusion opening does not exceed 2 microns.
  • the radii in the corners or edges of the extrusion opening 21 are smaller than 0.5 mm.
  • This blank has been warm hardened. Its dimensions are sufficiently accurate and the surfaces defining the extr-usion opening 21 are highly smooth. There are no cracks in the edge portions of the extrusion opening and it is therefore possible to use die 20 for extruding therethrough aluminum alloys into a shape corresponding to that of extrusion opening 21.
  • the wear and tear on die 20 is very high, particularly if relatively hard aluminum-silicon-magnesium alloys are to be extruded. Even by taking greatest care with respect to extrusion temperature, extrusion speed and lubricating agents, the useful lifespan of die 20 is rather limited so that the costs of providing the die will amount to about 6% of the total cost of the aluminum bodies extruded therethrough, since aluminum alloy particles adhere on the die 20.
  • the high cost of nitriding are due to the following:
  • the nitriding bath consists of a molten salt mixture containing cyanides and cyanates and having a temperature of 570 C.
  • Such salt mixture is commercially available under the trademark Tenifer.
  • -Die 20 remains in the molten salt bath for minutes and thereby, due to diffusion, an alloy or compound zone is formed having a thickness of about 20 microns and consisting essentially of iron carbide and iron nitride.
  • This alloy zone is very hard but also very thin.
  • the hardened die is removed from the salt bath at a temperature of 570 C. It has to be quenched or at least quickly cooled since otherwise the surfaces would corrode.
  • Cooling in an ambient atmosphere causes the formation of irregular corrosion layers and a roughness of about 5 microns. Consequently, it is necessary to work the thus-roughened surfaces. This is difficult and expensive because the surfaces have now been nitrided. Furthermore, such working removes a substantial portion of the hard nitride layer. In addition, such cooling in ambient atmosphere is connected with the danger of dimensional distortion due to interior heat tensions. Further working by grinding is extremely difficult and causes removal of another portion of the hard layer.
  • the dies 20 were hardened as before for 80 minutes at 570 C. in a nitriding salt bath and then removed therefrom.
  • the thus-hardened dies were simply transported through the ambient atmosphere into the pressure vessel 3 of FIG. 1 and hung into the same.
  • the time required for the removal of the hardened die from the salt bath to closing. lid of pressure vessel 3 after insertion of the die into the pressure vessel amounted to about 30 seconds and the temperature drop during this period equaled about 1.5 C. per second or a total of about 45 C.
  • vacuum pump 4 was actuated and thereby the drop in temperature by heat conduction and convection was quickly effectively reduced.
  • the residual pressure in the pressure vessel amounted to mm. mercury.
  • the temperature loss at the surface of the hardened work piece was reduced from 1.5 C. to only about 0.035 C. per second so that the average temperature loss during these two minutes amounted to 023 C. per second.
  • pressure vessel 3 was 14 opened and it was found that the die 20 located therein had a temperature of less than 200 C. (estimated).
  • the first measurement was made 12 seconds after opening of the lid 10 and at that time the surface temperature of the die, probably due to contact with the air entering the pressure vessel, was less than C.
  • Example 2 The work piece illustrated in FIG. 3 of the drawing, i.e., a forging die, was subjected to the process of the present invention.
  • the weight of die 30 was 1.65 kg. and the die was formed of a chromium-molybdenum steel of the type H13.
  • Hardening of the die was carried out as described in Example 1 by immersing the die in the nitriding salt bath maintained at 570 C.
  • the pressure vessel 3 was provided with water cooling in its cylindrical wall. Tap water was passed in contact with the wall of the pressure vessel so that the outer temperature of the wall remained below ambient temperature and the spent cooling water was heated to a ten-.- perature of only between about 20 and 30 C.
  • Example 3 The crank shaft illustrated in FIG. 4 was subjected to nitriding and cooling in accordance with the present invention. Before nitriding the forged shaft was warm hardened.
  • crank shaft was produced by drop forging of the alloy identified as 42CrMo4, and weighed 11.2 kg.
  • Hardening was carried out as described in Example 1 at a temperature of 570 C.
  • the residence time of the crank shaft in the salt bath was 90 minutes and it was found that the thickness of the hard compound surface zone was more than 20 microns.
  • crank shaft 40 Due to the greater size of crank shaft 40 as compared with the wonk pieces described in Examples 1 and 2, the extent of cooling during transfer of the work piece from the bath into the pressure vessel was somewhat less and amounted only to 35 C. and to the point at which the residual pressure of 15 mm. mercury was reached only to about 60 C.
  • the residence time of the crank shaft in evacuated pressure vessel 3' was 4 hours and upon subsequent removal the temperature of the crank shaft was 160 C.
  • a method of nitriding a ferrous workpiece comprising the steps of immersing said workpiece in a molten nitriding salt bath at a temperature significantly above than about 100 C.; evacuating said pressure vessel promptly after introduction of said workpiece into the same to a residual pressure of up to about 20 mm. Hg; and allowing said workpiece to cool by heat radiation while located in the thus evacuated zone and simultaneously cooling said pressure vessel to counteract the heating of the walls of the pressure vessel during cooling of the workpiece.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
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US730216A 1967-05-17 1968-05-16 Nitriding method Expired - Lifetime US3560271A (en)

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Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2977897A1 (fr) * 2011-07-15 2013-01-18 Hydromecanique & Frottement Procede de refroidissement de pieces metalliques ayant subi un traitement de nitruration / nitrocarburation en bain de sel fondu, l'installation pour la mise en oeuvre du procede et les pieces metalliques traitees
WO2019006554A1 (en) * 2017-07-07 2019-01-10 Industries Mailhot Inc. METHOD AND SYSTEM FOR COOLING METALLIC PARTS AFTER NITRURATION
US20220216649A1 (en) * 2019-04-10 2022-07-07 Icotek Project Gmbh & Co. Kg Device for introducing cables through an opening
CN117488046A (zh) * 2023-10-26 2024-02-02 烟台大学 一种实现高硬耐磨60NiTi合金的热处理装置及其方法

Cited By (15)

* Cited by examiner, † Cited by third party
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US9464346B2 (en) 2011-07-15 2016-10-11 H.E.F. Method for cooling metal parts having undergone a nitriding/nitrocarburising treatment in a molten salt bath, unit for implementing said method and the treated metal parts
TWI580793B (zh) * 2011-07-15 2017-05-01 Ｈｅｆ公司 用於冷卻已受到熔鹽浴氮化或氮化滲碳處理的金屬部件之方法，用於實施該方法之設備，及所處理的金屬部件
CN103732784A (zh) * 2011-07-15 2014-04-16 H.E.F.公司 用于冷却已经在熔盐浴中经历氮化/氮碳共渗处理的金属零件的方法，用于实施所述方法的设备及处理过的金属零件
JP2014520960A (ja) * 2011-07-15 2014-08-25 アッシュ・ウー・エフ 溶融塩浴における窒化／浸炭窒化処理を受けた金属部品を冷却するための方法、上記方法を実施するためのユニット、及び処理された金属部品
CN103732784B (zh) * 2011-07-15 2015-11-25 H.E.F.公司 用于冷却金属零件的方法，用于实施所述方法的设备及处理过的金属零件
RU2596539C2 (ru) * 2011-07-15 2016-09-10 Х.Э.Ф. Способ охлаждения металлических деталей, которые были подвергнуты обработке азотированием/нитроцементацией в ванне с расплавленной солью, устройство для осуществления способа и обработанная металлическая деталь
WO2013011228A1 (fr) 2011-07-15 2013-01-24 H.E.F. Procédé de refroidissement de pièces métalliques ayant subi un traitement de nitruration / nitrocarburation en bain de sel fondu, l'installation pour la mise en oeuvre du procédé et les pièces métalliques traitées
AU2012285581B2 (en) * 2011-07-15 2017-06-29 H.E.F. Method for cooling metal parts having undergone a nitriding/nitrocarburising treatment in a molten salt bath, unit for implementing said method and the treated metal parts
FR2977897A1 (fr) * 2011-07-15 2013-01-18 Hydromecanique & Frottement Procede de refroidissement de pieces metalliques ayant subi un traitement de nitruration / nitrocarburation en bain de sel fondu, l'installation pour la mise en oeuvre du procede et les pieces metalliques traitees
WO2019006554A1 (en) * 2017-07-07 2019-01-10 Industries Mailhot Inc. METHOD AND SYSTEM FOR COOLING METALLIC PARTS AFTER NITRURATION
US11352689B2 (en) 2017-07-07 2022-06-07 Industries Mailhot Inc. Method and system for cooling metal parts after nitriding
US20220216649A1 (en) * 2019-04-10 2022-07-07 Icotek Project Gmbh & Co. Kg Device for introducing cables through an opening
US12040574B2 (en) * 2019-04-10 2024-07-16 Icotek Project Gmbh & Co. Kg Device for introducing cables through an opening
CN117488046A (zh) * 2023-10-26 2024-02-02 烟台大学 一种实现高硬耐磨60NiTi合金的热处理装置及其方法
CN117488046B (zh) * 2023-10-26 2024-05-14 烟台大学 一种实现高硬耐磨60NiTi合金的热处理装置及其方法

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GB1214406A (en) 1970-12-02
DE1533970B1 (de) 1972-09-14
BE715214A (cs) 1968-09-30
FR1577966A (cs) 1969-08-14

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