Cast product having alumina barrier layer
a technology of alumina barrier layer and alumina, which is applied in the direction of solid-state diffusion coating, record information storage, textiles and paper, etc., can solve the problems of internal oxidization or cementation of the base material, insufficient function of preventing oxygen or carbon entry, and bloated oxide film
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first embodiment
[0069]The first embodiment according to the present invention provides a cast product in which an alumina barrier layer containing Al2O3 is formed on a surface of a cast body, and the cast body contains C: 0.3 mass % to 0.7 mass %, Si: 0.1 mass % to 1.5 mass %, Mn: 0.1 mass % to 3 mass %, Cr: 15 mass % to 40 mass %, Ni: 20 mass % to 55 mass %, Al: 2 mass % to 4 mass %, rare earth element: 0.005 mass % to 0.4 mass %, W: 0.5 mass % to 5 mass % and / or Mo: 0.1 mass % to 3 mass %, and 25 mass % or more of Fe in the remainder and an inevitable impurity, and 80 mass % or more of the rare earth element is occupied by La. In this description, “%” is “mass %” unless otherwise specified.
[0070]C: 0.3% to 0.7%
[0071]C has a function of improving the castability and increasing the high temperature creep rupture strength. Therefore, C is contained in at least 0.3%. However, when the content is too large, primary carbide of Cr7C3 tends to be widely formed, and migration of Al that forms the alumina ...
second embodiment
[0122]In the second embodiment according to the present invention, a cast product formed with a so-called “alumina barrier layer” containing Al2O3 on the surface is obtained by conducting a surface treatment by an acid treatment on a heat resistant alloy containing 15% or more of Cr and 20% or more of Ni, and 2% to 4% of Al, and then conducting a heat treatment.
[0123]Influences of the components contained in the cast product are described in the part of in the first embodiment.
[0124]The contents of the components contained in the cast product of the second embodiment are as follows.
[0125]Cr: 15% or More
[0126]Cr is contained in 15% or more, and the upper limit is 40%. The content of Cr is more desirably 20% to 30%.
[0127]Ni: 20% or More
[0128]Ni is contained in at least 20% or more. Since the effect of increasing the amount is not obtained when Ni is contained in more than 55%, the upper limit is 55%. The content of Ni is more preferably 28% to 45%.
[0129]Al: 2% to 4%
[0130]Al is contai...
third embodiment
[0168]The third embodiment according to the present invention obtains a cast product in which a welded part is formed by a so-called “alumina barrier layer” containing Al2O3, by joining a first cast body and a second cast body made of a heat resistant alloy containing 15% or more of Cr and 20% or more of Ni, and 2 to 4% of Al by welding, and subjecting a welded part between the welded first cast body and the second cast body to a surface treatment, and then subjecting the welded part to a heat treatment.
[0169]The influence of the component contained in the cast product is described in the part of in the first embodiment.
[0170]The contents of the components contained in the cast product of the third embodiment are identical to those in the second embodiment.
[0171]The first cast body and the second cast body forming the cast product of the third embodiment according to the present invention are casted to have the aforementioned composition by producing molten metal, followed by centr...
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Abstract
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