Cast product having alumina barrier layer

Abstract

To provide a cast product having an alumina barrier layer and method for producing the same. A cast product having an alumina barrier layer of the present invention is a cast product in which an alumina barrier layer containing Al 2 O 3 is formed on the 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 La.

What is claimed is: 
     
         1 . A cast product comprising a cast body having a surface formed with an alumina barrier layer containing Al 2 O 3 ,
 wherein 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% or more of the rare earth element is La.   
     
     
         2 . The cast product according to  claim 1 , wherein the rare earth element does not contain Ce. 
     
     
         3 . The cast product according to  claim 1 , wherein the rare earth element contains 0.1 mass % or less of Ce. 
     
     
         4 . The cast product according to  claim 1 , wherein the cast body further contains at least one kind selected from the group consisting of Ti: 0.01 mass % to 0.6 mass %, Zr: 0.01 mass % to 0.6 mass % and Nb: 0.1 mass % to 3.0 mass %. 
     
     
         5 . The cast product according to  claim 2 , wherein the cast body further contains at least one kind selected from the group consisting of Ti: 0.01 mass % to 0.6 mass %, Zr: 0.01 mass % to 0.6 mass % and Nb: 0.1 mass % to 3.0 mass %. 
     
     
         6 . The cast product according to  claim 3 , wherein the cast body further contains at least one kind selected from the group consisting of Ti: 0.01 mass % to 0.6 mass %, Zr: 0.01 mass % to 0.6 mass % and Nb: 0.1 mass % to 3.0 mass %. 
     
     
         7 . The cast product according to  claim 1 , wherein the cast body further contains more than 0 mass % and 0.1 mass % or less of B. 
     
     
         8 . The cast product according to  claim 2 , wherein the cast body further contains more than 0 mass % and 0.1 mass % or less of B. 
     
     
         9 . The cast product according to  claim 3 , wherein the cast body further contains more than 0 mass % and 0.1 mass % or less of B. 
     
     
         10 . The cast product according to  claim 4 , wherein the cast body further contains more than 0 mass % and 0.1 mass % or less of B. 
     
     
         11 . The cast product according to  claim 5 , wherein the cast body further contains more than 0 mass % and 0.1 mass % or less of B. 
     
     
         12 . The cast product according to  claim 6 , wherein the cast body further contains more than 0 mass % and 0.1 mass % or less of B. 
     
     
         13 . The cast product according to  claim 1 , wherein the alumina barrier layer has a thickness of 0.05 μm to 3 μm. 
     
     
         14 . The cast product according to  claim 1 , wherein the cast body covered with the alumina barrier layer has a surface roughness (Ra) of 0.05 μm to 2.5 μm. 
     
     
         15 . The cast product according to  claim 1 , wherein the cast body is produced by centrifugal casting.