Impeller, impeller manufacturing method, and rotating machine

Abstract

An impeller includes: a disc portion fixed to a rotary shaft rotating around an axis line; a cover portion disposed to face the disc portion; and a plurality of blade portions provided between the disc portion and the cover portion. A compressive residual stress layer is provided on a surface layer of a boundary with the disc portion and on a surface layer of a boundary with the cover portion, at a front end of each of the blade portions.

1 . An impeller, comprising:
 a disc portion fixed to a rotary shaft rotating around an axis line;   a cover portion disposed to face the disc portion; and   a plurality of blade portions provided between the disc portion and the cover portion, wherein   a compressive residual stress layer is provided on a surface layer of a boundary with the disc portion and on a surface layer of a boundary with the cover portion, at a front end of each of the blade portions.   
     
     
         2 . The impeller according to  claim 1 , wherein
 each of the blade portions and the disc portion are integrally provided or joined at the boundary with the disc portion, and   each of the blade portions and the cover portion are integrally provided or joined at the boundary with the cover portion.   
     
     
         3 . A method of manufacturing an impeller that includes a disc portion fixed to a rotary shaft rotating around an axis line, a cover portion disposed to face the disc portion, and a plurality of blade portions provided between the disc portion and the cover portion, the impeller manufacturing method comprising applying, by shot peening, compressive residual stress to a surface layer of a boundary with the disc portion and to a surface layer of a boundary with the cover portion, at a front end of each of the blade portions. 
     
     
         4 . The impeller manufacturing method according to  claim 3 , wherein the application of the compressive residual stress by the shot peening is performed at least in two stages of a first step using a first shot having a first particle diameter and a second step using a second shot having a second particle diameter smaller than the first particle diameter. 
     
     
         5 . A rotating machine comprising the impeller according to  claim 1 . 
     
     
         6 . A rotating machine comprising the impeller according to  claim 2 .