Classifications

• • 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
  • B22F5/00—Manufacture of workpieces or articles from metallic powder characterised by the special shape of the product
  • B22F5/10—Manufacture of workpieces or articles from metallic powder characterised by the special shape of the product of articles with cavities or holes, not otherwise provided for in the preceding subgroups
• • 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
  • B22F2999/00—Aspects linked to processes or compositions used in powder metallurgy
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
  • B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
  • B23K35/00—Rods, electrodes, materials, or media, for use in soldering, welding, or cutting
  • B23K35/001—Interlayers, transition pieces for metallurgical bonding of workpieces
• • 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
  • C21D2241/00—Treatments in a special environment
  • C21D2241/01—Treatments in a special environment under pressure
  • C21D2241/02—Hot isostatic pressing

Definitions

• the present invention is related to manufacturing components produced by means of powder-metallurgical manufacturing processes. More precisely, the invention relates to manufacturing components including internal concaves and channels.
• the manufacturing method thereby comprises typically the following main steps: o 1. Manufacturing a gas-atomized powder.
• Hot-isostatic pressing by means of temperature and pressure (e.g. for steels typically T 1100 - 1200°, pressure 100 - 120 MPa and time 1 - 4 h).
• the capsule die is manufactured as over-sized, in order to take into account0 the volumetric change of the encapsulated powder when the gas-atomized powder is consolidated.
• the density is 60-70 % of the theoretical density, in other words, the capsule can contract significantly when the powder is consolidated into the density of 100 %.
• Control of the dimensional changes taking place, when the powder is consolidated, is essential for achieving the dimensional accuracy of the5 products and naturally it has an essential influence on the production costs due to the amount of tooling allowances and the need for machining.
• a powder metallurgic method using hot isostatic pressing is also applicable for manufacturing products having internal channels and cavities, e.g. for heating and cooling of components.
• Cavities and channels can be manufactured by making into the powder capsule a capsule corresponding with the desired channel and cavity structure and by filling with powder the space between the capsule surrounding the whole structure and the capsule forming the channel and cavity.
• the accuracy of the location of these channels is in general critical with respect to the heating or cooling of the components and, in addition, it can have influence on the mechanical reliability of the structure.
• One alternative that has been used to some extent is to use solid basic materials, the joint surfaces of which are confronted against each other accurately.
• the joint surfaces are placed in the surrounding capsule so that the pressure in the hot isostatic pressing presses the surfaces against each other, thus providing a diffusion bonding.
• the surfaces of the solid pieces to be joined must be well finished, especially clean and even, to ensure an adequate quality of the bonding.
• the temperature and pres- sure of the hot isostatic pressing must be increased and the time prolonged compared with a powder metallurgic bonding, in order to ensure the good quality of the bonding.
• even the smallest impurities of the joint surfaces or moving of the surfaces during the hot isostatic pressing can prevent the bonding or weaken its quality significantly.
• the component is manufactured so, that substantially solid, preformed pieces produced by forging, casting or machining are used, and material in powder form, in an encapsulated space, is used for the joint surfaces of the solid pieces to be joined by isostatic pressing, More precisely, the method in accordance with the invention is characterized in by what has been stated in the characterizing part of Claim 1.
• Figures la - lc show examples of embodiments of the method in accordance with the invention.
• Figure la shows one embodiment of an application of the method in accordance with the invention.
• the joint area of the solid pieces 1, 1' and 1" has been sealed with gas-tight welds 3 and a capsule plate 4.
• the area formed in that way has been filled with powder material 2.
• the welds between the joint surfaces have been partly made directly between the solid pieces.
• the gas tightness is a precondition for using the hot isostatic pressing.
• the powder has been consolidated by means of pres- sure and/or temperature, like for example by hot isostatic pressing.
• the capsule plates and welds connected thereto can remain in the component or they can be removed for example by machining and in certain cases by acid etching.
• the amount of powder to be used in the joint has been minimized.
• the area formed into the jointing point of the solid pieces 1, 1' and 1" has been filled with powder 2 and solid material 5 in order to minimize the amount of the powder material.
• the joint area is sealed gas tightly by means of gas tight welds 3 and a capsule plate 4.
• the requirements for the dimensional accuracy of the joint surfaces are not as big as when using only solid materials.
• the oxide films of the junctions of the powder and solid material are efficiently broken, thus providing a more reliable and better joint compared with the solid-solid-joint.
• the amount of the powder to be used is very much limited only at the junctions of the pieces to be joined, the dimensional changes caused by the contraction of the powder are not big, whereby more accurate dimensions are achieved after the hot isostatic pressing, than by using as basic material a capsule totally filled with powder or powder encapsulated on the surface of the solid material.
• the capsule surrounding the joint surfaces can be (I) welded to the solid materials at both sides of the joint, (II) the whole interior of the concave or the channel can be encapsulated and (III) in addition, gas-tight capsules can be manufactured between the solid materials, said capsules transmitting the isostatic gas pressure to the joint surface and consolidating the powder between the joint surfaces.
• Components having more accurate dimensions can be manufactured by means of the method in accordance with the present invention, than by using materials manufactured by means of powder only or by using powder encapsulated into the surface of the solid material for sealing the internal concaves,
• the joints in the components are mainly free of welding joints; welding joints can be left to the gas tight welds surrounding the joint surfaces inside the component, but they form only a small part of the load bearing cross surface, and in addition, eventual welding mistakes not opening to the surface are closed during the hot isostatic pressing.

Landscapes

• Engineering & Computer Science (AREA)
• Manufacturing & Machinery (AREA)
• Mechanical Engineering (AREA)
• Pressure Welding/Diffusion-Bonding (AREA)
• Powder Metallurgy (AREA)

Applications Claiming Priority (2)

Publications (1)

Family

ID=8566331

Family Applications (1)

Country Status (3)

Family Cites Families (6)

• 2003
  • 2003-06-30 FI FI20030980A patent/FI120230B/fi active IP Right Grant
• 2004
  • 2004-06-30 WO PCT/FI2004/000408 patent/WO2005000504A1/en active Application Filing
  • 2004-06-30 EP EP04742151A patent/EP1638718A1/en not_active Withdrawn

Non-Patent Citations (1)

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