EP0043999A1 - Procédé pour la coulée par centrifugation d'une pièce en métal - Google Patents

Procédé pour la coulée par centrifugation d'une pièce en métal Download PDF

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Publication number
EP0043999A1
EP0043999A1 EP81105149A EP81105149A EP0043999A1 EP 0043999 A1 EP0043999 A1 EP 0043999A1 EP 81105149 A EP81105149 A EP 81105149A EP 81105149 A EP81105149 A EP 81105149A EP 0043999 A1 EP0043999 A1 EP 0043999A1
Authority
EP
European Patent Office
Prior art keywords
metal
mold
casting
melting point
lighter
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.)
Granted
Application number
EP81105149A
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German (de)
English (en)
Other versions
EP0043999B1 (fr
Inventor
Igor Y. Khandros
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.)
PepsiAmericas Inc
Original Assignee
Abex Corp
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 Abex Corp filed Critical Abex Corp
Publication of EP0043999A1 publication Critical patent/EP0043999A1/fr
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
    • B22D19/00—Casting in, on, or around objects which form part of the product
    • B22D19/16—Casting in, on, or around objects which form part of the product for making compound objects cast of two or more different metals, e.g. for making rolls for rolling mills
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
    • B22D13/00—Centrifugal casting; Casting by using centrifugal force
    • B22D13/02—Centrifugal casting; Casting by using centrifugal force of elongated solid or hollow bodies, e.g. pipes, in moulds rotating around their longitudinal axis

Definitions

  • This invention relates to centrifugal casting and in particular casting centrifugally alloys containing a substantial amount of a light, easily oxidized element, either as a pure metal or a light alloy itself.
  • Castings employed under oxidation, carburization or corrosion conditions at elevated temperatures are usually cast from an alloy containing a high percentage of chromium.
  • the problems of chromium substitution, lower chromium content or increase of the service life of a chromium-containing alloy are of great importance.
  • One of the main alternatives for chromium as an element providing oxidation-corrosion resistance is aluminum, but unfortunately high aluminum steels cast in air are generally unacceptable due to poor castability and the large amounts of dross and oxides present in the metal.
  • One of the objects of the present invention is to produce a centrifugally cast tube of a heat-resistant alloy high in aluminum content (especially at the ID surface) while nonetheless producing a casting free of objectionable dross and oxide inclusions.
  • Another object of the present invention is to be able to produce at will gradients of concentration of the oxidizable element in the cross section of the casting.
  • Another object of the invention in a broader sense is to cast an easily oxidized metal, or a metal containing an easily oxidized element centrifugally while precluding atmospheric oxygen.
  • Typical centrifugal mold apparatus is shown in Fig. 1 comprising a centrifugal mold 10.
  • the molten metal for the casting pours from the end of a spout 13A which is part of a pouring vessel 13. Because of the rotating mold the entrant metal, whatever its kind, spirals down the ID of the mold, as the molten metal will act like any other free body of liquid seeking its own level, especially with the force of the reservoir (vessel 13) behind it.
  • a light, low melting point metal 12 was deposited in the same way on the ID of the mold, having solidified, and as shown in Fig. 1 a heavier metal 14 having a much higher melting point is being deposited on the previous layer of lighter metal 12.
  • the lighter metal is dissolved only in the O.D. adjustment zone of the molten tube and, therefore, this zone is lighter than the rest of the metal. Because of centrifugal force, the heavier metal 14 will gravitate in the direction of the outside (OD) diameter of the centrifugal mold, or stated in other words, the lighter metal will be at the ID of the resultant cast tube T.
  • the first stage is solidification of the light metal followed next by the occurrence of the heavier, high melting point spiralling across the earlier deposited light metal, Fig. 1.
  • the taper shown for the lighter metal in Fig. 1 is actual, and is desirable in some cases for the achieving of a uniform ID alloyed layer, especially when a lower rotating speed of the mold is employed.
  • the third stage the melted metals attain uniform wall thickness with the heavier metal at the ID, but because the mold continues to rotate the heavier metal moves to the OD, Fig. 1B, where it remains while the casting cools to the solid state during the last stage.
  • a No. 356 aluminum alloy (6.5 to 7.0 % silicon) was poured at 1450 0 F into the rotating mold which had been preheated to 400 F.
  • a heat-resistant alloy (HRA alloy) of 35 % nickel, 19 % chromium, 0.42 % carbon, 1.2 % silicon and 1.2 % manganese (balance iron except for impurities) is poured at 2900°F onto the earlier formed, thin aluminum "tube" 12 from the same end of the mold.
  • the resultant centrifugally cast tube is found to contain three zones of metal:
  • Aluminum oxide clusters were observed only near the inside diameter (ID) surface of the tube, and in surprisingly small quantities for an air-melted heat containing so much aluminum.
  • the three zones (1), (2), and (3) are designated in Figs. 2 and 3.
  • the OD for the most part is the HRA alloy identified above but containing evenly distributed aluminum nitrides while the aluminum-rich alloy at the ID contains Fe-Ni-Al with some chromium carbides precipitated in intermetallic phases precipitated in interdendritic areas.
  • the standard HRA melt covered and remelted the aluminum alloy which was then shifted toward the inside diameter during continued rotation of the mold.
  • some aluminum is dissolved in the HRA alloy during the shift, lowering the melting point of the alloy at the OD.
  • the greater alloying with aluminum occurs at the ID, lowering the melting point of that alloy still further.
  • the ID may be covered by an aluminum-rich oxide film providing protection against further oxidation. Those light oxide inclusions which get underneath the film do not propagate deeply into the metal owing to their light weight and the centrifugal force.
  • a tube cast centrifugally in the manner of the present invention will exhibit higher corrosion, oxidation and carburization resistance compared to the corresponding HRA alloy having no aluminum.
  • the aluminum-rich layer at the ID having heavy precipitation of intermetallic phases and carbides will be harder and will exhibit improved abrasion resistance for those applications where hardness is a controlling factor.
  • the hardness measured at the ID surface of several tubular products produced according to the present invention was up to 430 BHN.
  • the process of the present invention may permit reduction in chromium content relying on aluminum substitution, especially for those applications where high temperature corrosion and oxidation resistance are most needed.
  • the HRA alloy specified above is only one of a whole host to which the invention may be applied.
  • a family of HRA alloys to which the present invention may be applied is given in Patent No. 4,077,801: Most of aluminum alloys may be employed without difficulty, depending on the final composition of metal required. Additions of other easily oxidized elements, such as titanium or boron, can be placed into the metal 12 in the form of a coarse powder of their low melting temperature alloys.
  • the principles of the invention would be equally applicable when replacing the HRA alloy with any steel such as a stainless steel, any other HRA alloy, or a nickel or cobalt base alloy; indeed the replacement can be any alloy melting appreciably higher and which is appreciably heavier than the light weight alloy and which is advantaged or improved by having the light weight, low melting point metal move therethrough while both are in the molten state.
  • the mold will be preheated at 350°F-400°F to avoid premature solidification when the lower melting point metal is first introduced to the mold cavity. Since the mold in most instances will have a mold wash lining (e.g. one sixteenth of an inch thick) on the inside diameter derived from a mixture of silica and water, heating the mold to drive off the water will also afford all, if not the major part of the preheat.
  • a mold wash lining e.g. one sixteenth of an inch thick
  • an HRA-aluminum alloy of the proportion specified above when poured all at once, will exhibit a drossy, porous, heavily oxidized ID which can be rendered acceptable only at an exhorbitant machining cost to reduce the wall thickness to a radius of sound metal; the loss in yield is prohibitive in most instances.
  • a further advantage is the ability to pour the HRA metal 14 at a temperature lower than heretofore.
  • the HRA metal or the high melting point metal is usually poured at a temperature considerably above the liquidus so it will not be solidified too quickly by the much cooler mold.
  • the lighter metal is aluminum because in that case the aluminum not only melts, becoming a "lubricant", it is dissolved in the HRA molten metal at the same time and heat or solution is generated, meaning the HRA metal need not be poured at the higher temperature to assure sustained fluidity.
  • the lower temperature results in a finer grain size which usually means (and in the case of HRA-aluminum) does mean a stronger casting.
  • a centrifugal mold 20 is provided with the usual end caps, but in this instance one end cap 22 is provided with one or more vent openings 24 and the other end cap 26 has a central aperture 26A of a size to admit a lance 28 which feeds a non-oxidizing gas such as argon into the mold interior after the light metal has solidified.
  • Argon displaces air out the vent hole, which is continued until the body of gas inside the mold is the non-oxidizing gas.
  • the lance is withdrawn and the openings in the end caps are temporarily sealed with a displaceable plug or rupturable diaphragm (not shown) which may be nothing more than a piece of plastic film.
  • the pouring spout 30 of a pouring vessel 32 is positioned in aperture 26A incidental to allowing molten metal 34 (heavy metal) to pour onto the previously poured light alloy at the inside diameter of the mold, which is being rotated.
  • the molten metal expands the gas (NG) which is forced from the mold at the vent 24 and at the annular venting space presented by aperture 26A.
  • NG gas
  • the non-oxidizing gas continues to be displaced as the molten metal spirals down the mold, seeking its own level as any other fluid body.

Landscapes

  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Molds, Cores, And Manufacturing Methods Thereof (AREA)
EP81105149A 1980-07-14 1981-07-02 Procédé pour la coulée par centrifugation d'une pièce en métal Expired EP0043999B1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US16872880A 1980-07-14 1980-07-14
US168728 1980-07-14

Publications (2)

Publication Number Publication Date
EP0043999A1 true EP0043999A1 (fr) 1982-01-20
EP0043999B1 EP0043999B1 (fr) 1986-01-29

Family

ID=22612701

Family Applications (1)

Application Number Title Priority Date Filing Date
EP81105149A Expired EP0043999B1 (fr) 1980-07-14 1981-07-02 Procédé pour la coulée par centrifugation d'une pièce en métal

Country Status (8)

Country Link
EP (1) EP0043999B1 (fr)
JP (2) JPS5846384B2 (fr)
AU (1) AU539855B2 (fr)
BR (1) BR8104464A (fr)
CA (1) CA1181223A (fr)
DE (1) DE3173614D1 (fr)
MX (1) MX155723A (fr)
ZA (1) ZA813806B (fr)

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE566714C (de) * 1931-03-19 1932-12-20 Peter Otto Verfahren zum Herstellen von Rohlingen
FR1304956A (fr) * 1961-11-03 1962-09-28 Deutsche Edelstahlwerke Ag Procédé et dispositif pour le moulage par centrifugation de matières métalliques sensibles à l'oxydation
FR2149294A1 (en) * 1971-08-18 1973-03-30 Apv Paramount Ltd Bi metallic tubes - with specified properties of inner or outer layers

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS4918696A (fr) * 1972-06-15 1974-02-19
JPS5550961A (en) * 1978-10-05 1980-04-14 Kubota Ltd Production of composite casting by centrifugal casting

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE566714C (de) * 1931-03-19 1932-12-20 Peter Otto Verfahren zum Herstellen von Rohlingen
FR1304956A (fr) * 1961-11-03 1962-09-28 Deutsche Edelstahlwerke Ag Procédé et dispositif pour le moulage par centrifugation de matières métalliques sensibles à l'oxydation
FR2149294A1 (en) * 1971-08-18 1973-03-30 Apv Paramount Ltd Bi metallic tubes - with specified properties of inner or outer layers

Also Published As

Publication number Publication date
DE3173614D1 (en) 1986-03-13
JPS58154448A (ja) 1983-09-13
AU7278981A (en) 1982-01-21
JPS5846384B2 (ja) 1983-10-15
JPS5747564A (en) 1982-03-18
CA1181223A (fr) 1985-01-22
AU539855B2 (en) 1984-10-18
EP0043999B1 (fr) 1986-01-29
MX155723A (es) 1988-04-20
ZA813806B (en) 1982-06-30
BR8104464A (pt) 1982-03-30

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