WO1993018195A1 - Procede de fabrication d'un corps fritte en poudre d'acier fortement allie - Google Patents

Procede de fabrication d'un corps fritte en poudre d'acier fortement allie Download PDF

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Publication number
WO1993018195A1
WO1993018195A1 PCT/CH1993/000043 CH9300043W WO9318195A1 WO 1993018195 A1 WO1993018195 A1 WO 1993018195A1 CH 9300043 W CH9300043 W CH 9300043W WO 9318195 A1 WO9318195 A1 WO 9318195A1
Authority
WO
WIPO (PCT)
Prior art keywords
steel powder
boron
sintered body
sintering
powder
Prior art date
Application number
PCT/CH1993/000043
Other languages
German (de)
English (en)
Inventor
Peter Ernst
Christoph Tönnes
Original Assignee
Asea Brown Boveri Ag
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
Application filed by Asea Brown Boveri Ag filed Critical Asea Brown Boveri Ag
Publication of WO1993018195A1 publication Critical patent/WO1993018195A1/fr

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Classifications

    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C33/00—Making ferrous alloys
    • C22C33/02—Making ferrous alloys by powder metallurgy
    • C22C33/0207—Using a mixture of prealloyed powders or a master alloy
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C33/00—Making ferrous alloys
    • C22C33/02—Making ferrous alloys by powder metallurgy
    • C22C33/0257—Making ferrous alloys by powder metallurgy characterised by the range of the alloying elements
    • C22C33/0278—Making ferrous alloys by powder metallurgy characterised by the range of the alloying elements with at least one alloying element having a minimum content above 5%
    • C22C33/0285—Making ferrous alloys by powder metallurgy characterised by the range of the alloying elements with at least one alloying element having a minimum content above 5% with Cr, Co, or Ni having a minimum content higher than 5%

Definitions

  • the invention is based on a method for producing a sintered body from high-alloy steel powder, in which the steel powder is heated to the sintering temperature, is kept at the sintering temperature for a predetermined period of time, and the sintered body formed in this way is subsequently cooled.
  • the invention relates to a state of the art, such as that specified in Metals Handbook Ninth Edition Vol.7 Powder Metallurgy, pp. 360 and 361.
  • a method for producing a sintered body is described in which steel powder precompressed to form a green body is compacted to form a sintered body at temperatures that are close to the melting point of the steel powder used.
  • it is generally necessary to densify the sintered body by hot isostatic pressing.
  • the invention is based on the object of specifying a method for producing a sintered body from a high-alloy steel powder which, at temperatures as low as possible, has a sintered body of high density and with favorable mechanical and chemical properties, in particular in the temperature range up to 600 ° C, delivers.
  • the method according to the invention is characterized in that extremely dense sintered bodies can be produced on the basis of a high-alloy martensitic steel powder by means of comparatively simple technological measures. These sintered bodies are regarding their mechanical and chemical behavior, in particular in the temperature range up to 600 ° C., comparable to sintered bodies produced according to the prior art, which, however, had to be subsequently hot-isostatically pressed in order to achieve the corresponding density.
  • the method according to the invention is based on the knowledge that boron added to the steel powder, at comparatively low sintering temperatures and without subsequent hot isostatic pressing, produces an extremely dense sintered body if the added boron is evenly distributed in the steel powder before sintering. In addition, it has been recognized that despite the presence of alloy components with a comparatively high partial pressure, such as chromium or manganese, there is no change in the stoichiometry of the steel powder during sintering.
  • a high-alloy steel powder of the type SS 422, preferably produced by atomization in a gas atmosphere, according to German nomenclature X 20 CrMoV 1 21, is used as the starting alloy.
  • the chemical composition of this steel powder is:
  • the proportion of phosphorus, sulfur, oxygen and nitrogen is less than 0.05 percent by weight.
  • This alloy is predominantly artsitic with smaller proportions of 5-ferrite and austenite.
  • the average particle size of the powder grains is less than 25 ⁇ m.
  • a cast body made from this material is characterized by a high 0.2 proof stress of approx. 1200 MPa after heat treatment at approx. 500 ⁇ C and by high creep resistance at temperatures up to 600 ⁇ C after heat treatment at 700 ⁇ C. Due to the high chromium content, this alloy is extremely corrosion-resistant and is particularly suitable for the production of corrosion-resistant components exposed to high temperatures, such as steam turbine blades in particular.
  • alloys with comparable mechanical and chemical properties and slightly different compositions, for example with chromium contents between 10 and 15%, in the production of sintered bodies by the process according to the invention.
  • a powder containing boron is also used as the starting material.
  • This powder can consist of elemental boron and / or a boron compound such as in particular iron boride.
  • it can have an average particle size of approximately 1 ⁇ m, but can advantageously also be selected to be larger.
  • Powders with larger particles, for example 10 or 20 ⁇ ra, are particularly advantageous if the steel powder and the boron-containing powder are to be mixed with one another comparatively quickly without agglomeration of boron-containing particles occurring.
  • boron-containing powders with small particles it is advantageous to grind the boron-containing powder and the steel powder together when mixing, since then agglomeration of boron-containing particles is avoided and a uniform distribution of the boron-containing particles in the steel powder is achieved. It is also highly recommended that boron be added to the steel powder by atomization, especially in a gas atmosphere, since then a particularly uniform distribution of boron in the steel powder is achieved and, moreover, the risk of introducing contaminants is virtually eliminated. This atomization can be combined with the production of the steel powder with particular advantage if the steel powder is produced by atomization of a starting alloy.
  • Graphite powder with a particle size of less than 150 ⁇ m can serve as a further starting material. This is of particular advantage if the starting alloy contains no or too little carbon during atomization.
  • At least 99.5 percent by weight steel powder, up to 0.3 - preferably 0.1 to 0.2 - percent by weight boron powder and up to 0.1 - preferably 0.05 - percent by weight graphite powder are mixed together in a mixer for about 30 minutes swirled. Batches of approx. 25 g powder each are then filled into cuboid shapes of approx. 50 mm ⁇ 15 mm ⁇ 15 mm from the mixed material.
  • the molds filled with loosely poured powder become Presintered into a sintering furnace provided with a nickel steel tube. A sintering gas which is at atmospheric pressure and preferably contains argon is fed to the furnace. The sintering furnace filled with the molds is heated to a temperature of approx.
  • prismatic bodies each having a dimension of 20 mm x 10 mm x 10 mm are cut from the presintered batches and these bodies in an evacuable sintering furnace provided with an aluminum oxide tube at temperatures between 1300 ° C. and 1380 "c in vacuum and / eiz- or preferably argon-containing gas atmosphere in a period of up sintered to five hours. on and cooling amount in this case up to 20 ⁇ C / min.
  • f from the steel powder volatilizing carbon s in this case is substantially compensated by the addition of the graphite powder
  • This compensation can also be achieved by adding a carbon monoxide-containing sinter gas during sintering above a temperature of, for example, 1000 ° C.
  • the steel powder is then carburized below a temperature of approximately 1200 ° C. Above a temperature of approximately 1200 ° C.
  • Decarburization then takes place when the sintered body is cooled 'an inert gas or vacuum is used at a temperature of about 1200 ° C as sintering gas, it can, with a suitable dosage of the supplied gases and can be achieved with a suitable length of time that the carbon content of the sintered body corresponds to the carbon content of the steel powder.
  • the density of the sintered bodies is determined, and the grain size of their structure is determined using micrographs.
  • the densities d (A) and d (B) and the grain sizes g (A) and g (B) of the sintered bodies A and B kept at the sintering temperature at approx. 1320 e C are compared.
  • the sintered body A produced by the process according to the invention contains the steel powder described above and 0.2% by weight of boron, while the sintered body B produced according to the prior art only contains the steel powder.
  • Particularly dense sintered bodies can be achieved if sintering is carried out first in a vacuum and then in a noble gas atmosphere which preferably contains argon. At the same time, a strong evaporation of the components of the steel powder and thus a weight loss of the sintered body compared to the weight of the starting materials is largely avoided. In addition, by backfilling the vacuum with argon, as soon as the pore structure of the sintered body is no longer connected to the surface, an additional densifying effect is achieved by the pressure difference between the pores (vacuum) and the furnace atmosphere (greater than 1 bar argon).

Landscapes

  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Mechanical Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Powder Metallurgy (AREA)

Abstract

Un procédé sert à produire un corps fritté en une poudre d'acier fortement allié. On chauffe la poudre d'acier jusqu'à la température de frittage, on la maintient pendant une période prédéterminée à cette température et on refroidit ensuite le corps fritté ainsi obtenu. Ce procédé permet de produire à des températures aussi réduites que possible un corps fritté de haute densité (d) ayant des propriétés mécaniques et chimiques favorables, notamment dans une plage de températures allant jusqu'à 600 °C. A cet effet, on ajoute à une poudre d'acier martensitique du bore élémentaire ou un composé de bore en tant qu'adjuvant de frittage, et on mélange uniformément le bore ajouté à la poudre d'acier avant le frittage.
PCT/CH1993/000043 1992-03-09 1993-02-22 Procede de fabrication d'un corps fritte en poudre d'acier fortement allie WO1993018195A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DEP4207379.0 1992-03-09
DE19924207379 DE4207379A1 (de) 1992-03-09 1992-03-09 Verfahren und herstellung eines sinterkoerpers aus hochlegiertem stahlpulver

Publications (1)

Publication Number Publication Date
WO1993018195A1 true WO1993018195A1 (fr) 1993-09-16

Family

ID=6453557

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/CH1993/000043 WO1993018195A1 (fr) 1992-03-09 1993-02-22 Procede de fabrication d'un corps fritte en poudre d'acier fortement allie

Country Status (3)

Country Link
CN (1) CN1076149A (fr)
DE (1) DE4207379A1 (fr)
WO (1) WO1993018195A1 (fr)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0921204A1 (fr) * 1997-12-05 1999-06-09 Daido Tokushuko Kabushiki Kaisha Poudre d'acier ferritique inoxydable pour corps fritté

Families Citing this family (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN1086615C (zh) * 1998-05-26 2002-06-26 北京科技大学 一种制备金属基颗粒增强复合材料的方法
CN1086616C (zh) * 1998-05-26 2002-06-26 北京科技大学 增分熔融凝固加工工艺的设备
AT411691B (de) * 2002-10-01 2004-04-26 Miba Sintermetall Ag Verfahren zum herstellen eines formkörpers aus sintermetall
CN106238740B (zh) * 2016-08-08 2018-02-02 长沙众聚达精密机械有限公司 纯铁与低活性钢低温强化连接方法

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4014680A (en) * 1975-01-22 1977-03-29 Allegheny Ludlum Industries, Inc. Prealloyed stainless steel powder for liquid phase sintering
EP0181317A2 (fr) * 1984-10-29 1986-05-14 Miba Sintermetall Aktiengesellschaft Procédé de fabrication d'un corps filtrant poreux à partir de poudre métallique
US4618473A (en) * 1985-06-14 1986-10-21 General Motors Corporation Iron powder article having improved toughness
FR2596067A1 (fr) * 1986-03-19 1987-09-25 Metafram Alliages Fritte Procede de fabrication de pieces en acier rapide fritte

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4678510A (en) * 1985-12-24 1987-07-07 General Motors Corporation Wear resistant iron powder article
KR910002918B1 (ko) * 1987-03-13 1991-05-10 미쯔비시마테리알 가부시기가이샤 Fe계 소결합금제 변속기용 동기링

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4014680A (en) * 1975-01-22 1977-03-29 Allegheny Ludlum Industries, Inc. Prealloyed stainless steel powder for liquid phase sintering
EP0181317A2 (fr) * 1984-10-29 1986-05-14 Miba Sintermetall Aktiengesellschaft Procédé de fabrication d'un corps filtrant poreux à partir de poudre métallique
US4618473A (en) * 1985-06-14 1986-10-21 General Motors Corporation Iron powder article having improved toughness
FR2596067A1 (fr) * 1986-03-19 1987-09-25 Metafram Alliages Fritte Procede de fabrication de pieces en acier rapide fritte

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0921204A1 (fr) * 1997-12-05 1999-06-09 Daido Tokushuko Kabushiki Kaisha Poudre d'acier ferritique inoxydable pour corps fritté
EP0921205A1 (fr) * 1997-12-05 1999-06-09 Daido Tokushuko Kabushiki Kaisha Corps fritté résistant à la corrosion, bague de capteur et pièce d'engagement utilisant ce corps
US6110252A (en) * 1997-12-05 2000-08-29 Daido Tokushuko Kabushiki Kaisha Powder for corrosion resistant sintered body having excellent ductility
US6149706A (en) * 1997-12-05 2000-11-21 Daido Tokushuko Kabushiki Kaisha Norrosion resistant sintered body having excellent ductility, sensor ring using the same, and engagement part using the same

Also Published As

Publication number Publication date
DE4207379A1 (de) 1993-09-16
CN1076149A (zh) 1993-09-15

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