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Publication numberUS3790303 A
Publication typeGrant
Publication dateFeb 5, 1974
Filing dateApr 5, 1972
Priority dateApr 8, 1971
Also published asDE2122353A1, DE2122353B2, DE2122353C3
Publication numberUS 3790303 A, US 3790303A, US-A-3790303, US3790303 A, US3790303A
InventorsEndres W
Original AssigneeBbc Brown Boveri & Cie
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Gas turbine bucket
US 3790303 A
Abstract
In a gas turbine bucket, having a blade and a root, composed of a eutectic alloy the blade is reinforced by eutectic fibers disposed in grain-orientated form, whilst in the root of the bucket the structure is non-orientated and enjoys a desirably high impact strength and ductility.
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United States Patent [1 1 Endres GAS TURBINE BUCKET [75] Inventor: Wilhelm Endres, Ennetbaden, Switzerland [73] Assignee: Aktiengesellschaft Brown, Boveri &

Cie, Baden, Switzerland [22] Filed: Apr. 5, 1972 [21] Appl. No.: 241,165

[30] Foreign Application Priority Data Apr. 8, 1971 Switzerland 5225/71 [52] US. Cl. 416/241 [51] Int. Cl. Fold 5/28 [58] Field of Search 416/241; 164/60, 122, 125, 164/127 [56] References Cited UNITED STATES PATENTS v 2,422,193 6/1947 Hague 416/241 UX Feb. 5, 1974 3,044,746 7/1962 Stargardter 416/241 3,260,505 7/1966 Ver Snyder... 416/214 X 3,342,455 9/1967 Fleck et al. 416/241 3,494,709 2/1970 Piearcey 416/241 X Primary Examiner-Everette A. Powell, Jr. Attorney, Agent, or Firm-Ralph B. Parker et al.

[5 7] ABSTRACT In a gas turbine bucket, having a blade and a root,

composed of a eutectic alloy the blade is reinforced by eutectic fibers disposed in grain-orientated form, whilst in the root of the bucket the structure is nonorientated and enjoys a desirably high impact strength and ductility.

4 Claims, 2 Drawing Figures 1 GAS TURBINE BUCKET This invention relates to turbine buckets, and is concerned with the development of quite different properties in different parts of the bucket, the chemical composition of the metal in the bucket being the same in both blade and root.

The prior art discloses gas turbine buckets which are reinforced by eutectic fibers, solidified in grainorientated form. They suffer from the disadvantage of having only a low notch impact strength. While a low notch impact strength in the blade of the bucket does not result in any substantial disadvantages, the bucket root itself suffers from the serious disadvantage that it is unable to deform itself sufficiently in the zone at which it is joined to the rotor.

An object of the present invention is to provide a gas turbine bucket, the blade of which is reinforced in known manner by eutectic fibers but having sufficient impact strength in the bucket root.

According to the invention this and other inventive objects are achieved in that in the gas turbine bucket, which is constructed of a eutectic alloy, the crystals embedded in the parent material are formed as fibers disposed longitudinally in parallel to the bucket blade and extending into the bucket root, the bucket root having a non-orientated structure.

The invention will now be explained in greater detail I hereinbelow, and with reference to the accompanying schematic drawing, in which:

FIG. 1 is a gas turbine bucket in section; and

FIG. 2 is an apparatus forproducing a gas turbine bucket of the-kind illustrated in FIG. 1. FIG. 1 shows a gas turbine bucket 1 comprising a bucket blade 2 and a bucket root 3. The gas turbine bucket l is composed 'of a eutectic alloy, the bucket blade having been subjected to grain-oriented solidification. The crystals embedded in the parent material 4 take the form of longitudinally parallel fibers 5 extending from the outer end of the bucket blade 2 through the blade and into the bucket root 3. A gas turbine bucket of this kind is constructed as follows.

A melt of a pseudo binary eutectic alloy Co1 ,,Cr Cr ,Co,C containing in weight percentages, 56.] percent cobalt, 40 percent chromium and 2.4 percent carbon, is cast into a precision mold of corundum. The precision mold 6 is introduced into a graphite succeptor 7 which may be inductively heated by means of a heating spiral 8. To this endthe precision mold 6 is introduced into the graphite succeptor 7 so that the bucket blade 2 and the upper quarter of the bucket root 3 are disposed in the graphite succeptor 7 while the lower part of the bucket root 3 extends from the aforementioned succeptor, as shown in FIG. 2.

The graphite succeptor 7 is heated to a temperature between .1 ,400 and l,600 C. and is maintained at the aforementioned temperature. Since the melting temperature of the alloy is 1,310 C., the melt forming the bucket blade is retained in the superheated, fluid state while the bucket root 3 solidifies. After solidification of the bucket root 3, the graphite succeptor 7 is moved upwardly in the direction of the arrow and axially relative to the precision mold 6, the velocity of the said motion being between 5 and cm/h. Accordingly, the melt solidifies in the upper quarter of the bucket root 3 and then in the bucket blade 2, the solidification front moving from the bucket root 3 to the upper end of the bucket blade 2. The gas turbine blade may be stripped from the mold as soon as the precision mold 6 has been entirely withdrawn from the graphite succeptor 7 and the melt has solidified.

By practicing this technique the blade structure is reinforced by eutectic fibers which are solidified in grain-oriented form, whilst in the root per se of the bucket the structure is non-oriented, as is illustrated in FIG. 1, and has an advantageous ductility at the operating temperature of the turbine bucket.

The method is also suitable for the following alloys:

' Co, ,,Cr TaC CoTaC Ni, ,,Cr -TaC. I claim: 1. Gas turbine bucket formed of a eutectic alloy and having a root and a bIade,-said blade having a crystalline structure oriented in parallel to the longitudinal orientation of the bucket blade whilst in the bucket root the structure is not grain-oriented and is ductile at the operating temperature of the turbine.

2. Gas turbine bucket according to claim 1, in the blade of which crystals embedded in matrix are present as fibers disposed longitudinally in parallel to the blade and extend through the blade and to the root per se.

3. Gas turbine bucket according to claim 1, in which the eutectic alloy is a member of the group of alloys consisting of CoCrC, NbNb C, Ta'Ta C,

Ni-Ni Nb, Ni Ni Ti, NiAlvCr, CoTiC, Ni-TaC,

' the alloy is a CoCrC alloy consisting essentially of 56.1 wt. percent cobalt, 40 wt. percent chromium and 2.4 wt. percent carbon.

Patent Citations
Cited PatentFiling datePublication dateApplicantTitle
US2422193 *Jun 12, 1944Jun 17, 1947Westinghouse Electric CorpMethod of making cast turbine blading
US3044746 *May 18, 1960Jul 17, 1962Gen ElectricFluid-flow machinery blading
US3260505 *Apr 17, 1964Jul 12, 1966United Aircraft CorpGas turbine element
US3342455 *Nov 24, 1964Sep 19, 1967Trw IncArticle with controlled grain structure
US3494709 *Feb 17, 1966Feb 10, 1970United Aircraft CorpSingle crystal metallic part
Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US4103063 *Mar 23, 1976Jul 25, 1978United Technologies CorporationCeramic-metallic eutectic structural material
US4190094 *Oct 25, 1978Feb 26, 1980United Technologies CorporationRate controlled directional solidification method
US4540038 *Jun 5, 1984Sep 10, 1985Westinghouse Electric Corp.Method for production of combustion turbine blade having a hybrid structure
US4637448 *Aug 27, 1984Jan 20, 1987Westinghouse Electric Corp.Method for production of combustion turbine blade having a single crystal portion
US4659288 *Dec 10, 1984Apr 21, 1987The Garrett CorporationDual alloy radial turbine rotor with hub material exposed in saddle regions of blade ring
US4712604 *Oct 14, 1986Dec 15, 1987The United States Of America As Represented By The Secretary Of The Air ForceApparatus for casting directionally solidified articles
US4850802 *Apr 21, 1983Jul 25, 1989Allied-Signal Inc.Composite compressor wheel for turbochargers
US5451142 *Mar 29, 1994Sep 19, 1995United Technologies CorporationTurbine engine blade having a zone of fine grains of a high strength composition at the blade root surface
US5468548 *Aug 2, 1993Nov 21, 1995United Technologies CorporationAluminum oxide, yttrium oxide
US20110293431 *Jan 8, 2010Dec 1, 2011Harald HardersComponent having varying structures and method for production
EP1818510A1 *Feb 8, 2006Aug 15, 2007Siemens AktiengesellschaftTurbine blade, especially for a gas turbine or a steam turbine
Classifications
U.S. Classification416/241.00R, 164/122.1
International ClassificationF01D5/28
Cooperative ClassificationF01D5/28
European ClassificationF01D5/28