Austenitic heat resistant alloy

Abstract

There is provided an austenitic heat resistant alloy having a chemical composition that contains, in mass percent: C: 0.03 to 0.25%, Si: 0.01 to 2.0%, Mn: 0.10 to 0.50%, P: 0.030% or less, S: 0.010% or less, Cr: 13.0 to 30.0%, Ni: 25.0 to 45.0%, Al: 2.5 to 4.5%, Nb: 0.01 to 2.00%, N: 0.05% or less, Ti: 0 to 0.20%, W: 0 to 6.0%, Mo: 0 to 4.0%, Zr: 0 to 0.10%, B: 0 to 0.0100%, Cu: 0 to 5.0%, REM: 0 to 0.10%, Ca: 0 to 0.050%, Mg: 0 to 0.050%, and the balance: Fe and impurities.

1 . An austenitic heat resistant alloy having a chemical composition consisting of, in mass percent:
 C: 0.03 to 0.25%;   Si: 0.01 to 2.0%;   Mn: 0.10 to 0.50%;   P: 0.030% or less;   S: 0.010% or less;   Cr: 13.0 to 30.0%;   Ni: 25.0 to 45.0%;   Al: 2.5 to 4.5%;   Nb: 0.05 to 2.00%;   N: 0.05% or less;   Ti: 0 to 0.20%;   W: 0 to 6.0%;   Mo: 0 to 4.0%;   Zr: 0 to 0.10%;   B: 0 to 0.0100%;   Cu: 0 to 5.0%;   REM: 0 to 0.10%;   Ca: 0 to 0.050%;   Mg: 0 to 0.050%; and   the balance: Fe and impurities.   
     
     
         2 . The austenitic heat resistant alloy according to  claim 1 , wherein the chemical composition contains, in mass percent, B: 0.0010 to 0.0100%. 
     
     
         3 . The austenitic heat resistant alloy according to  claim 1  or  claim 2 , wherein in a case where the alloy is heated in an atmosphere containing steam at 900° C. for 20 hours and subsequently heated in an H 2 —CH 4 —CO2 atmosphere at 1100° C. for 96 hours, a continuous alumina layer having a thickness ranging from 0.5 to 15 μm is formed on a surface of the alloy. 
     
     
         4 . The austenitic heat resistant alloy according to  claim 3 , wherein in the case where the alloy is heated in the atmosphere containing steam at 900° C. for 20 hours and subsequently heated in the H 2 —CH 4 —CO 2  atmosphere at 1100° C. for 96 hours, a layer having a Cr—Mn-based spinel structure formed on the alumina layer has a thickness of 5 μm or less. 
     
     
         5 . The austenitic heat resistant alloy according to  claim 2 , wherein in a case where the alloy is heated in an atmosphere containing steam at 900° C. for 20 hours and subsequently heated in an H 2 —CH 4 —CO 2  atmosphere at 1100° C. for 96 hours, a continuous alumina layer having a thickness ranging from 0.5 to 15 μm is formed on a surface of the alloy. 
     
     
         6 . The austenitic heat resistant alloy according to  claim 5 , wherein in the case where the alloy is heated in the atmosphere containing steam at 900° C. for 20 hours and subsequently heated in the H 2 —CH 4 —CO 2  atmosphere at 1100° C. for 96 hours, a layer having a Cr—Mn-based spinel structure formed on the alumina layer has a thickness of 5 μm or less. 
     
     
         7 . An austenitic heat resistant alloy having a chemical composition comprising, in mass percent:
 C: 0.03 to 0.25%;   Si: 0.01 to 2.0%;   Mn: 0.10 to 0.50%;   P: 0.030% or less;   S: 0.010% or less;   Cr: 13.0 to 30.0%;   Ni: 25.0 to 45.0%;   Al: 2.5 to 4.5%;   Nb: 0.05 to 2.00%;   N: 0.05% or less;   Ti: 0 to 0.20%;   W: 0 to 6.0%;   Mo: 0 to 4.0%;   Zr: 0 to 0.10%;   B: 0 to 0.0100%;   Cu: 0 to 5.0%;   REM: 0 to 0.10%;   Ca: 0 to 0.050%;   Mg: 0 to 0.050%; and   the balance: Fe and impurities.