Precipitation hardened fe-ni alloy

Abstract

Provided is a precipitation hardened Fe—Ni alloy having the following constitutions: (1) the precipitation hardened Fe—Ni alloy including: from 0.01 to 0.08% by mass of C, from 0.02 to 1.0% by mass of Si, not more than 1.0% by mass of Mn, from 36.0 to 41.0% by mass of Ni, 14.0 or more and less than 20.0% by mass of Cr, from 0.01 to 3.0% by mass of Mo, from 0.1 to 1.0% by mass of Al, from 1.0 to 2.5% by mass of Ti, and from 2.0 to 3.5% by mass of Nb, with the balance being Fe and unavoidable impurities; (2) the precipitation hardened Fe—Ni alloy satisfying the following formulae: Ni≧6×Nb+17 and Nb/(Ti+Al)≧0.8.

What is claimed is: 
     
         1 . A precipitation hardened Fe—Ni alloy having the following constitutions:
 (1) the precipitation hardened Fe—Ni alloy comprising: 
 from 0.01 to 0.08% by mass of C, 
 from 0.02 to 1.0% by mass of Si, 
 not more than 1.0% by mass of Mn, 
 from 36.0 to 41.0% by mass of Ni, 
 14.0 or more and less than 20.0% by mass of Cr, 
 from 0.01 to 3.0% by mass of Mo, 
 from 0.1 to 1.0% by mass of Al, 
 from 1.0 to 2.5% by mass of Ti, and 
 from 2.0 to 3.5% by mass of Nb, 
 with the balance being Fe and unavoidable impurities; 
 (2) the precipitation hardened Fe—Ni alloy satisfying the following formulae (1) and (2):
   Ni≧6×Nb+17   (1)
 
   Nb/(Ti+Al)≧0.8   (2).
 
 
 
     
     
         2 . The precipitation hardened Fe—Ni alloy according to  claim 1 , further comprising from 0.0005 to 0.01% by mass of B. 
     
     
         3 . The precipitation hardened Fe—Ni alloy according to  claim 1 , wherein an area percentage of a carbide after a solution heat treatment is 0.4% or more. 
     
     
         4 . The precipitation hardened Fe—Ni alloy according to  claim 2 , wherein an area percentage of a carbide after a solution heat treatment is 0.4% or more. 
     
     
         5 . The precipitation hardened Fe—Ni alloy according to  claim 1 , further comprising from 0.05 to 1.0% by mass of Cu. 
     
     
         6 . The precipitation hardened Fe—Ni alloy according to  claim 1 , further comprising from 0.05 to 1.0% by mass of V. 
     
     
         7 . The precipitation hardened Fe—Ni alloy according to  claim 1 , further comprising at least one element selected from the group consisting of Zr, Ta, W, Hf, Mg, and REM, provided that a total content thereof is from 0.001 to 0.50% by mass. 
     
     
         8 . The precipitation hardened Fe—Ni alloy according to  claim 1 , further comprising from 0.0005 to 0.01% by mass of Ca. 
     
     
         9 . The precipitation hardened Fe—Ni alloy according to  claim 1 , wherein 0.2% offset yield strength at room temperature is 900 MPa or more. 
     
     
         10 . The precipitation hardened Fe—Ni alloy according to  claim 1 , further satisfying the following formula (3):
   Cr+3Mo+5Cu≧19   (3).