US3730501A - Apparatus for treatment of metal products - Google Patents

Apparatus for treatment of metal products Download PDF

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Publication number
US3730501A
US3730501A US00098673A US3730501DA US3730501A US 3730501 A US3730501 A US 3730501A US 00098673 A US00098673 A US 00098673A US 3730501D A US3730501D A US 3730501DA US 3730501 A US3730501 A US 3730501A
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US
United States
Prior art keywords
shapes
enclosure
furnace
atmosphere
lock
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.)
Expired - Lifetime
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US00098673A
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English (en)
Inventor
A Gueussier
R Tricot
M Lacoude
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.)
Ugine Aciers SA
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Ugine Aciers SA
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Filing date
Publication date
Application filed by Ugine Aciers SA filed Critical Ugine Aciers SA
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    • 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 shapes are heated electrically or with liquid or gaseous fuels and mostfrequently in oxidizing atmospheres. Thereafter, the surface oxides are removed in a twostage operation.
  • the shapes are mechanically scoured by sanding or shot-blasting, or the shapes are chemically scoured or pickled by immersing them in baths of molten salts.
  • the shapes are scoured or pickled in an acid bath.
  • the shapes are heat treated, for example in a bath of molten salts, followed by acid stripping or pickling.
  • the heat treatment is under vacuum followed by acid stripping or pickling.
  • the industrial methods which consist of heating in a nonoxidizing atmosphere have the important advantage of not causing additional oxidation on the metal surface. This is also the case when the annealing or tempering treatment is under vacuum as described in the French Pat. No. 1,205,079 of Nov. 3, 1958.
  • the oxidized steel shapes are heated in a vacuum at a temperature of approximately l,0OO to 1,100 C. Thereafter, the shapes are cooled in the presence of a protective gas. The rate of cooling of the shapes in the gas excludes any possibility of fast quenching.
  • the process comprises the steps of first heating oxidized shapes in a closed container kept under vacuum close to 0.1 torr at a temperature of approximately l,050 C for several hours, passing a protective nitrogen atmosphere into the container, transferring the shapes exposed to the atmosphere to a quenching bath, and finally pickling the shapes in an acid bath to eliminate the porous layer of residual oxide.
  • This process is burdensome and costly. It causes superficial decarburization of the steel shapes treated. Finally, this process does not avoid the necessity ofsubsequent scouring or pickling.
  • the oxidized shapes are placed in an enclosure containing a reducing atmosphere under a pressure between and 0.01 torr, and heated to temperatures between 700 and 1,200 C, in contact with a carbonaceous reducing agent, after which they are cooled in a nonoxidizing environment.
  • the carbonaceous reducing agent may be gaseous and may also provide the required reducing atmosphere. It may also consist of a thin liquid or solid layer, for example of a hydrocarbon or of a fine suspension of a solid reducing agent, such as graphite in a liquid deposited on the treated metal.
  • the total quantity of specific carbonaceous reducing agent should be sufficient in each case for all the surface oxides of the metal to be reduced, without exerting an action on the metal itself.
  • the reducing atmosphere may be generated by injection of a gaseous reducing agent into the enclosure. It may also be generated by injection of a liquid or solid reducing agent, at least partially gasified under the temperature and pressure conditions prevailing in the enclosure. ln particular, it may be generated by partial gasification of a thin layer of liquid hydrocarbons deposited on the shapes to be processed.
  • a heat treatment furnace which essentially comprises a sealed enclosure with pumping devices and heating devices, whereby the required pressure and temperature may be reached and maintained; devices for communication between the surroundings and the enclosure allowing the insertion and withdrawal of the shapes to be descaled without reducing the vacuum and without permitting air to enter the enclosure; means of injection and/or coating the shapes with a carbonaceous reducing agent; and means for cooling the products in a neutral atmosphere before emerging into the atmosphere.
  • the furnace is isolated from the surrounding atmosphere by means of at least one barometric lock.
  • a barometric lock may be fomied in a U-shaped well or elbow filled with the carbonaceous reducing liquid.
  • One of the branches of the bend is in communication with the furnace. The other is connected to the surrounding atmosphere.
  • the two branches of the bend or well are equipped with lowering and lifting mechanisms which render it possible to insert the shapes to be processed through the liquid in the well. It is plain that the outlet of the furnace may be equipped with another U-shaped well filled with any appropriate liquid.
  • the shapes processed according to our invention are inserted into the furnace and removed from this furnace without breaking the vacuum seal. They are coated with the carbonaceous reducing agent at the same time.
  • the nature of the liquid present in the well or wells does not affect the atmosphere of the furnace.
  • the components subjected to the treatment according to our invention may be quenched during their extraction from the furnace, in a liquid, without being in contact with air.
  • FIG. 1 is a schematic section view of a furnace according to this invention
  • FIG. 2 is a detailed section through a barometric charging and discharging joint useful in this invention
  • FIG. 3 is a plan view of the elevator system in one of the legs of the barometric joint.
  • FIG. 4 is a plan view of the elevator mechanism of both legs of the joint.
  • One embodiment of this invention diagrammatically illustrated in a section in FIG. 1-, consists of providing the processing furnace 1 with a toroidal shape having one orifice 2 in communication with a barometric well or lock 3.
  • the lock 3 is in the shape of a U whose two branches are marked 4 and 5.
  • the lock simultaneously serves for inserting the shapes (incorporated coating) and of extracting them (with quenching). It contains an oil, for example, a quenching oil.
  • the levels of oil 6 in the two branches 4 and have the positions shown.
  • the shapes under treatment travel in a definite direction in the furnace.
  • the raising and lowering mechanisms (shown schematically as a movable hydraulic piston and cylinder 19, but which could be any other suitable raising and lowering device) take the shape to be treated, 7, lower it to 8 at the bottom of branch 4 below the separation level 9, cause it to pass to 10 at the bottom of branch 5 and raise it to 11 up to the orifice 2.
  • the product enters the furnace at 12 and is carried in a definite direction around the toroidalshaped furnace.
  • a shape which has already passed through the furnace is then placed on the raising and lowering mechanisms.
  • the shape is subjected to quenching in the oil of the well before moving out into the atmosphere.
  • a continuously operating furnace is thus obtained, the vacuum pipe being marked 14 and a hydrocarbon injector 13.
  • the injection of the carbonaceous reducing agent occurs through one or more adjustable valves or through any other analogous device.
  • the number and location of such devices corresponds to the thermal cycle selected, to the desirable vacuum, and to the capacity of the furnace.
  • the heating system is comprised of graphite elements 20, for example.
  • the outlet of furnace l is a cooling lock 15 having doors l6 and 17.
  • Means 18 are provided to maintain the atmosphere in the cooling lock inert.
  • the joint of FIG. 2 is a U-shaped shaft made up of two cylindrical sleeves connected with one another at the base. Leg of the U is connected to the furnace interior 26 in a tight manner. The other leg 27, which opens into the open air, is sufficiently set off to allow ready access to the articles that are to be put into the furnace or to the articles that have been removed from the furnace.
  • This U-shaped shaft is partially filled with a liquid whose level is established in each sleeve as a function of the pressure existing above each free surface. This means particularly that the level of the liquid can be the same in the two legs when the lock chamber is at atmospheric pressure. This may. be the case when the furnace chamber is under atmospheric pressure.
  • This liquid which is suitable for coating the products that are to be treated according to the method of the invention (and possibly for tempering) fulfills the function of the hydraulic joint, thereby assuring isolation of the lock chamber from the atmosphere.
  • the articles that are to be treated are brought at 28 by means of any fixed or autonomous device to the charging elevator (shown in broken lines in the raised position at 29) and the elevator is then made to descend to the bottom position.
  • the charging elevator shown in broken lines in the raised position at 29
  • This elevator is composed of a frame 31 (FIG. 3) equipped with two sets of guide rollers such as 32 and 33 (FIGS. 2 and 3) which roll on vertical rails such as 34 (FIGS. 2 and 3) in such a manner that the vertical movement will be strictly rectilinear.
  • This frame is coupled to at least one endless chain 35 (FIG.-2) which is guided over its entire elevation and is wound, on the one hand, over a control wheel 36 (FIGS. 2 and 4) moved by a set of motor reducers 37 (FIG. 4), and on the other hand, over a slidably mounted wheel 38 (FIG. 2) for regulating the tension of the chain.
  • Each chain executes a back and forth (ascending-descending) motion whose extreme positions are governed by two endof-the-stroke devices, the one for travel at low speed before stopping, the other for stopping.
  • the device used here for pushing the charge is a rack bar pusher 41 (FIG. 4) having a pusher 42 (FIGS. 2 and 4) provided in front with a suitably shaped shield and on its lower portion with a rack bar having a control pinion whose movement is assured by a set of motor reducers 43 (FIG. 4) outside of the chamber through a tight rotary joint 44 (FIG. 4).
  • the positions of end-ofstroke and stop-on-return are controlled by an end-ofstroke selector likewise positioned outside of the chamber and actuated by the entry shaft of the rotary joint.
  • the shaft has a tight cover 46 (FIG. 2) on its upper portion which permits access. It also has a sliding trap door 47 (FIG. 2) which makes it possible to isolate the furnace chamber and to reach the corresponding elevator without being obliged to rupture the vacuum or to change the atmosphere of the lock chamber.
  • This trap door generally concealed in a protuberance, is controlled by an external set of motor reducers which act upon a rack bar hinged to the trap door.
  • the upper portion of the trap door has a joint which cooperates with a mechanical bearing surface, the closing being assured by jacks.
  • the lock chamber includes devices for feeding the liquid, for controlling the level, for cooling, and recirculating the liquid 50.
  • a furnace for heat treating and descaling metal shapes consisting of a wall forming a sealed furnace enclosure, means for maintaining a subatmospheric pressure within said furnace enclosure, means for heating the shapes within the furnace enclosure, means for maintaining a reducing atmosphere within the furnace enclosure, and means for inserting and extracting the shapes in said enclosure, said inserting and extruding means comprising a U-shaped tube having two upright legs containing a carbonaceous reducing liquid for coating the shapes prior to entry into the sealed furnace enclosure and for forming a barometric lock therewith, one of said upright legs connected directly to and hermetically sealing with said enclosure, said liquid established at different heights in the different legs of the tube means after application of subatmospheric pressures to the enclosure, means for moving the shapes through the tube means so as to coat the shapes with said carbonaceous reducing liquid and then move them into the enclosure.
  • a device for moving shapes to and from an enclosure maintained at subatmospheric pressures comprising a U-shaped tube having spaced upright legs, one leg connected directly to and hermetically sealing with the enclosure and the other communicating with the atmosphere, a carbonaceous reducing liquid in said tube for coating the shapes prior to entry into the sealed furnace enclosure and for forming a barometric lock therewith, said legs sufficiently long to support a barometric column of said fluid, means for raising and lowering the shapes in each leg so as to coat the shapes with said carbonaceous reducing liquid, means for transferring the shapes from one elevating means to another.
  • a device in which there is provided a means for pumping fluid from the bottom of the U-shaped tube to the top of the leg in communication with the enclosure.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Thermal Sciences (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Mechanical Engineering (AREA)
  • Physics & Mathematics (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Heat Treatment Of Strip Materials And Filament Materials (AREA)
  • Heat Treatment Of Articles (AREA)
  • Solid-Phase Diffusion Into Metallic Material Surfaces (AREA)
  • Heat Treatments In General, Especially Conveying And Cooling (AREA)
US00098673A 1967-08-01 1970-12-16 Apparatus for treatment of metal products Expired - Lifetime US3730501A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
FR116523 1967-08-01

Publications (1)

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US3730501A true US3730501A (en) 1973-05-01

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US00098673A Expired - Lifetime US3730501A (en) 1967-08-01 1970-12-16 Apparatus for treatment of metal products

Country Status (9)

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US (1) US3730501A (xx)
AT (1) AT279997B (xx)
BE (1) BE717757A (xx)
DE (1) DE1758666B1 (xx)
FR (1) FR1555588A (xx)
GB (1) GB1238047A (xx)
LU (1) LU56589A1 (xx)
NL (1) NL6810931A (xx)
SE (1) SE344340B (xx)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6025536A (en) * 1997-08-20 2000-02-15 Bristol-Myers Squibb Company Process of manufacturing a cobalt-chromium orthopaedic implant without covering defects in the surface of the implant

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3796615A (en) * 1971-06-23 1974-03-12 Hayes Inc C I Method of vacuum carburizing
NL8204477A (nl) * 1982-11-18 1984-06-18 Bekaert Sa Nv Katalysator, alsmede werkwijze ter vervaardiging van deze katalysator en haar toepassing.

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1634319A (en) * 1924-10-27 1927-07-05 Erwin C Uihlein Method and apparatus for heat treating metal articles
US3360252A (en) * 1965-10-13 1967-12-26 Hayes Inc C I Furnace construction having step-by-step gravitational feed

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE970605C (de) * 1950-07-21 1958-10-09 Telegraph Constr & Maintenance Verfahren und Vorrichtung zum fortlaufenden Gluehen von Metallbaendern und Draehten unter Luftabschluss

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1634319A (en) * 1924-10-27 1927-07-05 Erwin C Uihlein Method and apparatus for heat treating metal articles
US3360252A (en) * 1965-10-13 1967-12-26 Hayes Inc C I Furnace construction having step-by-step gravitational feed

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6025536A (en) * 1997-08-20 2000-02-15 Bristol-Myers Squibb Company Process of manufacturing a cobalt-chromium orthopaedic implant without covering defects in the surface of the implant

Also Published As

Publication number Publication date
LU56589A1 (xx) 1968-10-31
AT279997B (de) 1970-03-25
BE717757A (xx) 1968-12-16
NL6810931A (xx) 1969-02-04
FR1555588A (xx) 1969-01-31
GB1238047A (xx) 1971-07-07
SE344340B (xx) 1972-04-10
DE1758666B1 (de) 1971-10-07

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