Bbc Brown, Boveri & Company, Limited

Bbc Brown Boveri Ag

Robert Singer

Gunther Schroder

Hans Rydstad

Mohamed Youssef Nazmy

Gernot H Gessinger

Bernd Jahnke

Roland Kunzli

Peter Jongenburger

Superalloy with oxide dispersion hardening having improved corrosion and oxidation resistance and based on nickel with the following composition:

Superalloy with oxide dispersion hardening having improved corrosion

Components (5) in a superalloy, in particular a dispersion hardened nickel based alloy, are connected together by pressure bonding in the solid condition with the greatest possible limitation of the overall deformation of the complete components (5) by lateral restraint (7), the actual bonding zone (6) having short-term intensive dynamic plastic flow imposed on it and, taking account of the deformation temperature, the local deformation rate .epsilon..sub.l and the local deformation .epsilon..sub.l referred to the bonding zone (6) are matched together in such a way that the driving force during the subsequent heat treatment of the complete workpiece above the recrystallization temperature is sufficient to force the formation of coarse grain under all conditions. It can then be assumed that, in general, the expression ##EQU1## h.sub.o =height of the bonding zone (6) before connection, h.sub.f =height of the bonding zone (6) after connection,

Method for connecting superalloy components

Components made of a dispersion-hardened superalloy are connected together by pressure bonding, the individual parts previously processed at their bonding surfaces only by milling, without fine machining such as grinding, electro-polishing, etc., being subjected before bonding to a heat treatment in the temperature range of between 60.degree. C. and 210.degree. C. below the recrystallization temperature for the purpose of reducing the driving force. During the subsequent coarse-grain heat treatment of the bonded workpiece, no sort of fine crystalline banding occurs in the bonding zone and the strength of the workpiece corresponds to that of the material before bonding.

Process for connecting components made of a dispersion-hardened

Method for applying a corrosion-protection layer to the base body (1) of a gas turbine blade by embedding particles (3) of SiC in a metallic matrix by means of powder, paste or electrolytic/electrophoretic methods and compacting, welding or fusing and bonding the matrix-forming material to the base body (1) by means of hot-pressing, hot isostatic pressing or laser beam, electron beam or electric arc. Protective layers are formed which do not flake off and with high silicon content which is at least partially contained in the embedded, partly modified SiC particles (6) as a reservoir for the operation.

Method for the application of a corrosion-protection layer containing

A fine-grained workpiece having improved mechanical properties is produced from a nickel-based superalloy by two-part forging, a blank being converted, in a first isothermal hot-forming step (curve b) above the solution-annealing temperature for the .gamma.'-phase (line a), into an intermediate form and the latter then being finally forged to give the end form in a second isothermal hot-forming step (curve c) just below the solution-annealing temperature for the .gamma.'-phase. For the first step, a degree of deformation .epsilon. of of at least 0.7 at a mean deformation rate .epsilon. of about 10.times.10.sup.-3 s.sup.-1 is required here. The second step is carried out at deformation rates .epsilon. which are one to two powers of 10 lower than those of the first step.

Process for producing a fine-grained workpiece from a nickel-based

Manufacture of a workpiece from a creep-resistant nickel superalloy which is hardened by means of an oxide dispersion, by a powder-metallurgical process in which the mechanically alloyed powder is subjected to an isothermal or quasi-isothermal hot-rolling operation, in the course of which the powder particles are converted into a flake-shaped form with a pronounced longitudinal axes, and the rolled powder is introduced into a steel container and is compressed by isostatic hot-pressing. The workpiece is afterwards subjected to an annealing treatment which is designed to develop a coarse grain size. A preferred embodiment comprises the introduction of the powder into the mold or container in an oriented manner, in order to obtain a stratified packing of the powder, and an annealing treatment which is designed to develop a coarse grain size and is performed as a zone-annealing treatment.

Process for the manufacture of a workpiece from a creep-resistant alloy

An apparatus and a process for the zone-annealing of a workpiece (1) consisting of a high-temperature material, in which the workpiece (1) is hung on a suspension device (2) actuated via a roller (3) driven by a drive motor (4) and is provided with a plate-shaped covering screen (10) having an orifice. For the dipping of the workpiece (1), there is underneath the latter a salt bath (5) which is enclosed in an insulating vessel (6) and is provided with a heating system (7) with centrally symmetrical guide plates (8) and which is closed off at the top by means of a floating insulating cover (9). The cooling of the part of the workpiece (1) which is not immersed is guaranteed by a cooling body (11) through which cooling air (14) flows and which has a central passage (12) and, at the lower end of the passage (12), a projecting edge (13) serving as a stop for the covering screen (10). The intended grain structure can be adjusted when the feed speed of the workpiece (1) is varied in portions by means of a drive motor (4) and the amount of cooling air (14). The lateral heat flux is reduced by means of jacket-like heat-insulating cladding of the workpiece (1).

Apparatus for the zone-annealing of a workpiece consisting of a

A component possessing high resistance to corrosion and oxidation, composed of a dispersion-hardened superalloy having a high creep strength, comprises a coarse-grained core (1) which has high strength at high temperatures, and a fine-grained skin zone (2) which forms a case. The component is manufactured with the aid of a heat-treatment, or thermomechanical treatment, in a manner such that, starting from a fine-grained initial condition, the skin zone (2) is restrained from participating in the recrystallization which leads to the formation of coarse grains in the core (1).

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Robert Singer