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Alloys with high corrosion resistance for engine valve applications

a technology of high corrosion resistance and alloy, applied in the field of alloys with high corrosion resistance for engine valve applications, can solve the problems of high cost, mechanical resistance and corrosion resistance, and the use of costly nickel-based superalloys, and achieve the effects of improving the creep resistance of alloy, increasing the alloy cost, and compromising the mechanical properties of alloy in terms of mechanical resistance and ductility

Inactive Publication Date: 2009-03-26
VILLARES METALS SA
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Benefits of technology

The patent text describes the development of a new material composition for exhaust valves that has improved high temperature resistance and corrosion resistance. The alloy uses a combination of niobium, chromium, aluminum, and titanium as the main alloy elements. The presence of intermetallic phases in the microstructure of the alloy is important for its performance. The alloy also contains a small amount of carbon, which helps to improve abrasive wear resistance. The alloy's properties are achieved through a careful selection of the alloy element compositions and their optimal distribution in the material.

Problems solved by technology

Such extreme stresses in terms of mechanical resistance and corrosion resistance at high temperatures require the use of costly nickel-based superalloys.
One example of an excellent performance alloy in these applications is the NCF 751 alloy, which is very costly because of its high nickel content, above 70%.

Method used

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  • Alloys with high corrosion resistance for engine valve applications
  • Alloys with high corrosion resistance for engine valve applications
  • Alloys with high corrosion resistance for engine valve applications

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Embodiment Construction

[0044]FIG. 1 depicts the heat resistance of the alloys compared to other known alloys. FIG. 2 shows the test oxidation resistance results. In such test, cylindrical test specimens (diameter=12 mm, height=14 mm), as solubilized and aged, were duly weighed and kept at an 800° C. temperature for 100 hours. After being removed from the furnace, the test specimen is air cooled and weighed again, and the mass variation is measured. The bigger the mass gain, the lower the oxidation resistance. Such process is repeated until the total test time is completed. Ceramic alumina crucibles were used as sample holders during the test. The oxidation process at 800° C. was reviewed for 400 hours, when it was possible to notice a stabilization of the corrosion process. The test was carried out so that all samples of all alloys involved had identical sizes, for them also to have an identical contact surface. FIG. 3 shows the oxidation resistance results as related to the Ti / Al ratio. The oxidation res...

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Abstract

Low cost alloys resistant to mechanical requirements related to high temperatures, resistant to corrosion, with high workability and which meet different requirements in the conditions for application in either exhaust or intake valves for internal combustion engines. The main features of the alloys is the precipitation of Ni3Nb in its microstructure. In percentage, its mass consists of: 0.01 to 0.15% C, up to 3.0% Mn, up to 1.0% Si, 18.0 to 25.0% Cr, 25.0 to 49.0% Ni, up to 0.50% Mo, up to 0.50% W, up to 0.50% V, up to 5.0% Cu, 1.0 to 3.0% Al, 0.5 to 2.5% Ti, 1.0 to 6.0% Nb, 0.001 to 0.02% B, 0.001 to 0.10% Zr, up to 2.0% Co, where (Ni+Co) is not higher than 50.0% in mass, nor lower than 25% in mass. As for the ration Al / Ti, it is lower than 2.0. The rest is made of iron and impurities inevitable to the Alloy manufacture procedure.

Description

[0001]This application claims benefit of provisional application 60 / 924,974, filed Jun. 7, 2007.FIELD OF THE INVENTION[0002]This invention deals with an Ni—Fe—Cr precipitation hardened superalloy for application in internal combustion engine valves, having as chief characteristics a high hot resistance through the precipitation of Ni3(Al,Ti,Nb) and a higher oxidation resistance as compared to the state-of-the-art alloys. The alloy project, based on its microstructure aspects, also allows for the alloy hereof to be provided with properties equal to or higher than those of the high nickel alloys used in internal combustion engine valves, associated with the alloy's significant cost reduction because of the lower nickel content.[0003]The alloy hereof is intended for valves' manufacture, where the alloy is required to have several properties, among them the following: high temperature oxidation resistance and heat resistance, because of the high temperatures used in the application.BACK...

Claims

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Application Information

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Patent Type & Authority Applications(United States)
IPC IPC(8): C22C30/02
CPCC22C30/02
Inventor BARBOSA, CELSO ANTONIOJARRETA, DAVID DELAGOSTINISOKOLOWSKI, ALEXANDRE
Owner VILLARES METALS SA
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