Howmet Turbine Components Corporation

Howmet Corporation

Louis E Dardi

Srinivasan Shankar

William R Freeman, Jr

Stewart J Veeck

Ranes P Dalal

Mark J Straszheim

Robert J Smickley

John M McFadden

Dinesh K Gupta

William R Freeman

The method of making a composite article of different metal portions by spraying molten metal on the surface of a solid metal member that has been cleaned and preheated in a controlled atmosphere at low pressure. The molten metal is sprayed on the surface of the solid metal member, preferably by plasma jet spraying. It is rapidly solidified to be adherent to the surface of the solid metal member to form a composite preform. The composite preform is cooled at a rate sufficiently low to reduce residual stresses and then hot pressed to eliminate voids in the sprayed metal portion and metallurgically bonded to the surface of the solid member.

Method of forming a composite article by metal spraying

A method of joining metal materials by spraying molten metal into a cavity between the articles to be joined. Prior to deposition of the metal, the surface of the cavity is cleaned and the articles to be joined are preheated. Subsequent to deposition of the metal within the cavity, the joined articles are cooled at a rate that precludes damage due to thermal effects and the deposited metal is consolidated in the cavity by hot pressing.

Method for joining materials by metal spraying

A nickel- or cobalt-based alloy of the type containing, by weight, 5 to 40% chromium, up to about 10% aluminum, up to about 10% titanium, up to about 30%, in combination, of elements from the group tantalum, tungsten, molybdenum, columbium, rhenium, or vanadium, up to about 2% silicon, up to about 5% hafnium, and up to about 5% reactive elements such as lanthanum, yttrium or other rare earths. Manganese is present in an amount from 0.1 to 12%, preferably 0.5 to 4%. Silicon in amounts from 1.0 to 2.0 by weight, or hafnium in amounts from 0.1 to 5.0% by weight may also be used. Alloys in accordance with this invention are particularly suitable for casting by the single crystal technique; however, the alloys can also be used in the production of polycrystalline components such as directionally solidified, conventionally solidified (equiaxed), wrought, or dispersion strengthened materials. In the latter case, grain boundary modifiers such as carbon, boron, zirconium and hafnium are utilized. The alloys produced are advantageously used as structural alloys for use in gas turbine rotor blades and stator vanes which require high temperature strength, high temperature ductility, oxidation and hot corrosion resistance, and microstructural stability.

Alloys for high temperature applications

A method of refining the microstructure of metals which undergo a phase transformation at high temperatures by diffusing a solute material into the metal at a temperature below the normal transformation temperature. The solute induces the phase transformation and removal of the solute at a temperature near the transformation temperature reverses the transformation. These phase transformations refine the microstructure of the metal so treated. The method is particularly useful to Group IVB metals i.e. Zr, Hf and Ti.

Microstructural refinement of cast metal

Coatings for iron-, nickel- and cobalt-base superalloys. The coatings are applied in order to provide good oxidation and/or sulfidation and thermal fatigue resistance for the substrates to which the coatings are applied. The coatings consist essentially of, by weight, 10 to 50% chromium, 3 to 15% aluminum, 0.1 to 10% manganese, up to 8% tantalum, up to 5% tungsten, up to 5% reactive metal from the group consisting of lanthanum, yttrium and other rare earth elements, up to 5 percent of rare earth and/or refractory metal oxide particles, up to 12% silicon, up to 10% hafnium, and the balance selected from the group consisting of nickel, cobalt and iron, and combinations thereof. Additions of titanium up to 5% and noble metals up to 15% are also contemplated.

Superalloy coating composition with oxidation and/or sulfidation

The microstructure of titanium is refined by inducing a high temperature transformation from .alpha.+.beta. to .beta. and back to .alpha.+.beta. by diffusing hydrogen into and then out of the metal while maintaining the metal above the temperature of hydride formation. The titanium is heated to a temperature just below the .alpha.+.beta. to .beta. transformation temperature, and hydrogen is diffused into the metal thereby inducing the phase change. The hydrogen is diffused out of the metal again inducing a phase change. When the hydrogen has been removed, the metal is allowed to cool to room temperature.

Microstructural refinement of cast titanium

Coatings for iron-, nickel- and cobalt-base superalloys and the resulting coated components having good high temperature oxidation resistance. The coatings consist essentially of, by weight, 5% to 50% chromium, 3% to 30% aluminum, 0.01% to 15% tantalum, up to 10% manganese, up to 5% tungsten, up to 12% silicon, up to 10% hafnium, up to 5% reactive metal from the group consisting of lanthanum, yttrium, and other rare earth elements, up to 5% of rare earth and/or refractory metal oxide particles, and the balance selected from the group consisting of nickel, cobalt and iron, and combinations thereof. Additions of titanium up to 5% and noble metals up to 15% are also contemplated.

Superalloy coating composition with high temperature oxidation resistance

Coatings for iron-, nickel- and cobalt-base superalloys. The coatings are applied in order to provide good oxidation/sulfidation and thermal fatigue resistance for the substrates to which the coatings are applied. The coatings consist essentially of, by weight, 10 to 50% chromium, 3 to 15% aluminum, 1.0 to 15% metal mixture from the group consisting of tantalum, tungsten, manganese and combinations thereof, up to 5% reactive metal from the group consisting of lanthanum, yttrium and other rare earth elements, up to 5 percent of rare earth and/or refractory metal oxide particles, and the balance selected from the group consisting of nickel, cobalt and iron, and combinations thereof. Additions of titanium up to 5% and noble metals up to 15% are also contemplated. Tantalum makes up at least 20% of the metal mixture or 0.5% of the total coating weight, whichever is greater. Tungsten, manganese, or a combination thereof, make up at least 0.5% of the total coating.

Superalloy coating composition

A method for producing precision shapes which includes the consolidation of powder metal preforms into a shaped porous preform. A first coating is applied to the preform, this first coating being porous while providing a diffusion barrier. A second coating which is also initially porous is then applied and the coated preform can then be degasified by subjecting the preform to a vacuum, particularly at elevated temperatures. The coated preform is then heated under vacuum to a temperature such that the second coating is densified to the extent that it becomes non-porous. Finally, the preform is subjected to a hot isostatic pressing operation whereby formation of high integrity, fully dense metal shape results.

Method for the production of precision shapes

A method for the production of metal articles resistant to corrosion at elevated temperatures. The method involves the application of a first coating on an article surface, this coating comprising a cobalt, iron or nickel alloy which is compatible with the substrate and which is ductile in character. A second coating highly resistant to corrosion at elevated temperatures is applied over the first coating to form a composite coating, and an elevated temperature treatment follows to provide interfacial bonding and to minimize the detrimental effects of thermal and mechanical stresses encountered during use. The provision of a ductile first layer provides a barrier against degradation of the corrosion resistance of the outer layer and serves as a barrier against detrimental interdiffusion and crack propagation.

Method for producing elevated temperature corrosion resistant articles

A method for producing cast, superalloy, ferrous and titanium articles comprising the formation of a material void in the cast article, for example by utilizing a core during the casting operation or by machining a void after casting. The void is sealed relative to the surrounding atmosphere and the article is then subjected to an elevated temperature and pressure treatment in a gaseous atmosphere whereby the metal in the area of the void will yield so that the void is partially or totally eliminated. The pressure application is carried out at a temperature such that local deformation of the cast structure occurs in the region previously occupied by, and adjacent to, the void whereby a fine-grained recrystallized structure is developed in this section. Grain refined cast articles are characterized by superior low-cycle fatigue and tensile properties.

Method for improving fatigue properties in castings

A process for providing coatings on metal articles whereby the articles will be resistant to corrosion at elevated temperatures. The process involves the application of an overlay on an article surface, the overlay comprising a ductile metal of a composition normally resistant to corrosion at elevated temperatures. An outer layer of aluminide or metal which is resistant to corrosion at elevated temperatures but which is subject to embrittlement at such temperatures is applied to complete the coating. Porosity in the coating is then eliminated and a high integrity corrosion resistant coating not subject to cracking is obtained by heating the article in a gaseous atmosphere to elevated temperature and simultaneously applying isostatic pressure to the article.

Process for producing elevated temperature corrosion resistant metal

A method for consolidating powder metal preforms and for thereby producing high performance metal shapes from powder particles. The powder particles are consolidated into a shaped porous preform, and a coating is then applied to the resulting preform. The coating is initially porous whereby the coated preform can be degasified by subjecting the preform to a vacuum, particularly at elevated temperatures. The coated preform is then heated under vacuum to a temperature such that the coating is densified to the extent that it becomes non-porous. The coated preform is then subjected to a hot isostatic pressing operation whereby formation of a high integrity, fully dense metal shape results.

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Muskegon, MI, United States of America

Louis E Dardi