EP0045984B1 - Verfahren zur Herstellung eines Werkstückes aus einer warmfesten Legierung - Google Patents

Verfahren zur Herstellung eines Werkstückes aus einer warmfesten Legierung Download PDF

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Publication number
EP0045984B1
EP0045984B1 EP81200670A EP81200670A EP0045984B1 EP 0045984 B1 EP0045984 B1 EP 0045984B1 EP 81200670 A EP81200670 A EP 81200670A EP 81200670 A EP81200670 A EP 81200670A EP 0045984 B1 EP0045984 B1 EP 0045984B1
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EP
European Patent Office
Prior art keywords
deformation
intermediate material
case
final
values
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
Application number
EP81200670A
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German (de)
English (en)
French (fr)
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EP0045984A1 (de
Inventor
Gernot Dr. Dipl.-Ing. Gessinger
Robert Dr. Dipl.-Ing. Singer
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.)
BBC Brown Boveri AG Switzerland
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BBC Brown Boveri AG Switzerland
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Priority to AT81200670T priority Critical patent/ATE6674T1/de
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    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22F—CHANGING THE PHYSICAL STRUCTURE OF NON-FERROUS METALS AND NON-FERROUS ALLOYS
    • C22F1/00—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working
    • C22F1/10—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working of nickel or cobalt or alloys based thereon
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F3/00—Manufacture of workpieces or articles from metallic powder characterised by the manner of compacting or sintering; Apparatus specially adapted therefor ; Presses and furnaces
    • B22F3/24—After-treatment of workpieces or articles
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C32/00—Non-ferrous alloys containing at least 5% by weight but less than 50% by weight of oxides, carbides, borides, nitrides, silicides or other metal compounds, e.g. oxynitrides, sulfides, whether added as such or formed in situ
    • C22C32/001—Non-ferrous alloys containing at least 5% by weight but less than 50% by weight of oxides, carbides, borides, nitrides, silicides or other metal compounds, e.g. oxynitrides, sulfides, whether added as such or formed in situ with only oxides
    • C22C32/0015—Non-ferrous alloys containing at least 5% by weight but less than 50% by weight of oxides, carbides, borides, nitrides, silicides or other metal compounds, e.g. oxynitrides, sulfides, whether added as such or formed in situ with only oxides with only single oxides as main non-metallic constituents
    • C22C32/0026—Matrix based on Ni, Co, Cr or alloys thereof

Definitions

  • the invention relates to a method for producing a workpiece according to the preamble of claim 1.
  • Oxide dispersion-hardened alloys in particular those of the nickel-based type, are generally produced by powder metallurgical methods, the technology of mechanical alloying of the powder particles being used to a large extent. In order to achieve the highest possible creep resistance at high temperatures, such alloys must have a coarse-grained structure in the ready-to-use workpiece.
  • the methods of mechanical alloying and the question of the associated further processing of the oxide dispersion-hardened materials are known (e.g. BJP Morse and JS Benjamin, "Mechanical Alloying", New Trends in Materials Processing, pp. 165-199, in particular pp. 177-185, American Society for Metals, seminar October 19/20, 1974).
  • the primary material obtained in a first compaction step (powder compaction) must be subjected to further shaping operations. Since both the material and the machining costs of such alloys are very high, this shaping can only be carried out economically by forming. At the end of all processes there is always a heat treatment which serves to convert the finished workpiece into the coarse-grained structure which is best suited for high-temperature operation.
  • the setting options for the coarse grain are known to depend on the available driving forces, the number of bacteria and other physical parameters. It is not indifferent in which way the primary material was created. The latter can be done, for example, by extrusion at high or low temperature or by hot isostatic pressing of the mechanically alloyed, encapsulated powder.
  • the mechanical alloying usually causes a state of the highest possible deformation, that is to say strain hardening driven to the saturation limit, which is more or less broken down in the subsequent thermomechanical deformation steps.
  • Practice shows that there is an optimal deformation state of the primary material for the subsequent formation of coarse grains ("normal”). If, on the other hand, the primary material is insufficiently deformed ("underworked”), i.e.
  • the invention is based on the object of specifying a production method for oxide-hardened, heat-resistant workpieces which, regardless of the selected compression step and the resulting state of deformation of the structure of the starting material produced in this way, guarantees a coarse-grained end product that is usable for operation.
  • Fig. 1 the flow diagram of the basic method is shown in block form. It is generally assumed that metallic powders, which may be in the form of elements and / or master alloys, and metal oxide powders as dispersoids.
  • the powders are very fine-grained, the particle size fluctuates between a few ⁇ m and about 60 ⁇ m, and the metal oxide powders are usually even finer (below 1 ⁇ m).
  • the mixing and mechanical alloying of the powders is generally carried out in a protective gas atmosphere in the attritor. The powder particles are alloyed to homogeneity and mixed with the dispersoid. At the same time, the cold working is driven to the saturation limit, which is reflected in the high hardness, which can reach up to 700 Vickers units.
  • the mechanically alloyed powder is filled into a ductile metal container, usually soft steel, under vacuum and encapsulated (sealed, sealed can or capsule on all sides).
  • the encapsulated powder is thermally compressed to 100% of the theoretical density.
  • the product is an easily deformable, ultra-fine-grained raw material, which forms the starting material for the further shaping of the workpiece.
  • the other parameter, the degree of deformation is expediently determined by the absolute value of the natural logarithm of the cross-sectional ratio of the workpiece. Of course, you can also start from the change in length and then convert it to the cross-sectional ratio.
  • FIG. 2 shows the flow diagram of the process steps for insufficiently deformed starting material.
  • a powder mix was mechanically alloyed and encapsulated in a soft steel can.
  • the Endlegiqrunig had the following composition:
  • the subsequent hot compression step consisted of extrusion at a temperature of 1075 ° C.
  • the fine-grained primary material produced in this way had an average particle size of 0.3 ⁇ m.
  • the workpiece was subjected to coarse grain annealing at a temperature of 1220 ° C for 1 h. An average grain size of over 100 ⁇ m was found. In general, given these conditions, coarse grain can be understood to mean that grain size which means a coarsening by at least a factor of 100 compared to the fine-grained starting material.
  • FIG. 3 shows the flow diagram of the process steps for optimally deformed starting material.
  • the starting position corresponded to the exemplary embodiment explained in FIG. 2.
  • the same alloy was used and the same first process steps were used.
  • the extrusion was carried out under similar conditions, but at a temperature of 960 ° C.
  • the reduction ratio likewise gave an e of 3.
  • the fine-grained starting material had a sub-grain size of 0.2 ⁇ m. In accordance with the breakdown of work hardening, this material was in the optimal state of deformation ("normal").
  • the average sub-grain size of these materials generally ranges from 0.15 ⁇ m to 0.25 ⁇ m.
  • FIG. 4 shows the flow diagram of the process steps for excessively deformed starting material.
  • a powder mixture was mechanically alloyed and encapsulated in a soft steel can.
  • the final alloy had the following composition:
  • thermoforming step to compress the encapsulated powder to 100% of the theoretical density consisted of hot isostatic pressing at a temperature of 950 ° C. for 4 hours under a pressure of 135 MPa.
  • the height of the original cylindrical body of 200 mm was reduced to 150 mm.
  • the corresponding ⁇ was 0.3.
  • the fine-grained primary material produced in this way had an average sub-grain size of 0.14 ⁇ m. Due to the lower breakdown of the work hardening of the powder, this material was considered to be excessively deformed ("overworked").
  • the subgrain size of such materials is usually ⁇ 0.15 ⁇ m.
  • the workpiece was subjected to coarse grain annealing at a temperature of 1220 ° C for 1 h. An average grain size of over 60 ⁇ m was determined, which clearly means coarse grain in this case.
  • FIG. 5 shows a diagram of the experimentally determined deformation conditions in order to achieve coarse grain for the finished workpiece in the event that insufficiently deformed starting material (“underworked”) is assumed.
  • the deformation conditions are shown as pairs of values for the deformation speed and the degree of deformation.
  • Each intersection of an abscissa value with an ordinate value represents a specific state that characterizes the deformation condition, but not a functional relationship between the deformation speed and the degree of deformation. If the intersection falls within the hatched area, the conditions for the success of subsequent coarse grain annealing on the finished workpiece are met. If the intersection falls outside the hatched area, coarse grain formation can no longer be expected. Either the recrystallization is then at least partially absent, or a fine-grained structure that is undesirable for operation is formed.
  • the rate of deformation must be kept within fairly narrow limits in order to achieve coarse grain, that an optimum value exists regardless of the degree of deformation and that the latter must not fall below a certain minimum.
  • the value for should be between 16.5 and 20, optimally around 18 (dash-dotted horizontal), while should be.
  • the favorable area in the diagram is open parallel to the abscissa, which means that there is no upper limit to the degree of deformation.
  • Fig. I is a diagram of the experimentally determined deformation conditions to achieve coarseness for the finished workpiece in the event that optimally deformed starting material ("normal") is assumed.
  • the hatched area again represents the totality of the intersection points of an abscissa and ordinate value, for which the coarse grain formation is guaranteed on the occasion of the subsequent annealing.
  • Has z. B a raw material according to the characteristics explained in Fig. 3, but with a deformation rate accordingly until deformed, no coarse grain was obtained after subsequent annealing at 1220 ° C / lh. The same material accordingly until deformed, clearly gave coarse grain.
  • the diagram shows that whenever larger deformations of the workpiece corresponding to ⁇ > 1.0 are necessary, the deformation speed has to be kept within narrow limits, which is the value for between 15.5 and 20, optimally around 18.
  • the value for s is not limited, so it can be as small as desired, in the limit case it can also be zero (no further transformation possible or desirable in practice).
  • Correspondingly in the area of low degrees of deformation for the final shaping is the range for the rate of deformation expanded and reached for Values that are between approximately 10 and 22. In practice, this means that in the case of small deformations (e.g. re-pressing to achieve higher accuracy and surface quality of the workpiece), the deformation speed for previously optimally deformed primary material is not as critical as for higher degrees of deformation.
  • FIG. 7 shows a diagram of the experimentally determined deformation conditions in order to achieve coarseness for the finished workpiece in the event that excessively deformed starting material ("overworked") is assumed.
  • the hatched area defined above approaches the ordinate, but does not quite reach it.
  • the permissible value for approximately between 14 and 18, for higher degrees of deformation accordingly between 16 and 20, optimal again at around 18. Otherwise there is a correspondingly lower deformation range for example a linear relationship with the mean of the logarithm of the rate of deformation.
  • the degree of deformation s must reach at least 0.1.
  • deformation conditions apply both to a single deformation step and to a complicated forming process consisting of partial steps. In any case, during the implementation of the last step the conditions mentioned above are met. From the above it is clear that ultimately the structural and work hardening condition of the primary material (i.e. the initial conditions) is largely irrelevant. It is always possible to achieve a coarse grain after the final annealing. Forming to the finished workpiece can be done by forging, rolling, pressing, hammering or hot drawing or any combination of these processes.
  • the starting material can be produced in a conventional manner by hot isostatic pressing or by extrusion.
  • the method is generally applicable to the alloy type specified in the examples and related dispersion-hardened austenitic superalloys which are suitable for precipitation hardening.
  • the working conditions to be observed for the further shaping of a workpiece from a dispersion-hardened nickel alloy were defined as pairs of values of deformation rate / degree of deformation in order to again achieve a coarse-grained structure which is optimal for operation at high temperatures and clearly represented in diagrams.
  • the process ensures, regardless of the ultra-fine-grained raw material and its degree of work hardening, that coarse grain is obtained in the end product.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Manufacturing & Machinery (AREA)
  • Powder Metallurgy (AREA)
  • Forging (AREA)
  • Press Drives And Press Lines (AREA)
EP81200670A 1980-08-08 1981-06-16 Verfahren zur Herstellung eines Werkstückes aus einer warmfesten Legierung Expired EP0045984B1 (de)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AT81200670T ATE6674T1 (de) 1980-08-08 1981-06-16 Verfahren zur herstellung eines werkstueckes aus einer warmfesten legierung.

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
CH602780 1980-08-08
CH6027/80 1980-08-08

Publications (2)

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EP0045984A1 EP0045984A1 (de) 1982-02-17
EP0045984B1 true EP0045984B1 (de) 1984-03-14

Family

ID=4303031

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EP81200670A Expired EP0045984B1 (de) 1980-08-08 1981-06-16 Verfahren zur Herstellung eines Werkstückes aus einer warmfesten Legierung

Country Status (4)

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EP (1) EP0045984B1 (enrdf_load_stackoverflow)
JP (1) JPS5754237A (enrdf_load_stackoverflow)
AT (1) ATE6674T1 (enrdf_load_stackoverflow)
DE (1) DE3162643D1 (enrdf_load_stackoverflow)

Families Citing this family (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3262679D1 (en) * 1981-09-03 1985-04-25 Bbc Brown Boveri & Cie Process for manufacturing an article from a heat-resisting alloy
CH661455A5 (de) * 1982-02-18 1987-07-31 Bbc Brown Boveri & Cie Verfahren zur herstellung eines feinkoernigen werkstuecks als fertigteil aus einer warmfesten austenitischen nickelbasislegierung oder aus der legierung a 286.
JPS60131943A (ja) * 1983-12-19 1985-07-13 Sumitomo Electric Ind Ltd 分散粒子強化耐熱耐摩耗アルミニウム合金粉末
CH671583A5 (enrdf_load_stackoverflow) * 1986-12-19 1989-09-15 Bbc Brown Boveri & Cie
DE59007734D1 (de) * 1989-05-16 1995-01-05 Asea Brown Boveri Verfahren zur Erzeugung grober längsgerichteter Stengelkristalle in einer oxyddispersionsgehärteten Nickelbasis-Superlegierung.

Family Cites Families (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
BE794801A (fr) * 1972-01-31 1973-07-31 Int Nickel Ltd Procede de recuit en zones d'alliages
GB1435796A (en) * 1972-10-30 1976-05-12 Int Nickel Ltd High-strength corrosion-resistant nickel-base alloy
US3909309A (en) * 1973-09-11 1975-09-30 Int Nickel Co Post working of mechanically alloyed products
CH599348A5 (enrdf_load_stackoverflow) * 1975-10-20 1978-05-31 Bbc Brown Boveri & Cie

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Publication number Publication date
DE3162643D1 (en) 1984-04-19
EP0045984A1 (de) 1982-02-17
ATE6674T1 (de) 1984-03-15
JPS5754237A (enrdf_load_stackoverflow) 1982-03-31

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