Ni-Cr-Fe Alloy For High-Temperature Use

Abstract

The present application relates to an alloy for use at high temperature. The invention is characterized in that the alloy consists principally of Ni, Cr and Fe and in that the alloy has a principal composition such that the levels of the elements Fe, Si, C, Nb and Mo lie within the following intervals, given in percentage by weight: Fe 5-13 Si 1-3 C <0.1 Nb <0.2 Mo <1.0 and in that Ni comprises the balance, while its level does not exceed 69% and in that the level of Cr is greater than Cr=15% and in that it is less than the lower of the two values Cr=5*Si−2.5*Fe +42.5 and Cr=25

1 . An alloy for use at high temperature, characterised in that the alloy consists principally of Ni, Cr and Fe and in that the alloy has a principal composition such that the levels of the elements Fe, Si, C, Nb and Mo lie within the following intervals, given in percentage by weight: Fe 5-13 Si 1-3 C <0.1 Nb <0.2 Mo <1.0 and in that Ni comprises the balance, while its level does not exceed 69% and in that the level of Cr is greater than Cr=15% and in that it is less than the lower of the two values Cr=5*Si−2.5*Fe+42.5 and Cr=25. 
     
     
         2 . An alloy according to  claim 1 , characterised in that Ni comprises the balance, while its level does not exceed 68%. 
     
     
         3 . An alloy according to  claim 1 , characterised in that Ni comprises the balance, while its level does not exceed 67%. 
     
     
         4 . An alloy according to  claim 1 , characterised in that Ni comprises the balance, while its level does not exceed 66%. 
     
     
         5 . An alloy according to  claim 3 , characterised in that the alloy contains up to 5% Co as a replacement for Ni. 
     
     
         6 . An alloy according to  claim 1 , characterised in that the alloy contains up to 0.8% Co as a replacement for Ni. 
     
     
         7 . An alloy according to  claim 1 , characterised in that the alloy contains up to 0.5% Co as a replacement for Ni. 
     
     
         8 . An alloy according to  claim 1 , characterised in that the alloy contains up to 0.1% Co as a replacement for Ni. 
     
     
         9 . An alloy according to  claim 1 , characterised in that it contains Al, Ca, Cu, Hf, Mg, Mn, Mo, N, Nb, Ta, Ti, V, W, Y, Zr and rare earth metals up to a total level of 7%, and in that the level of impurities constitutes a maximum of 1%. 
     
     
         10 . An alloy according to  claim 1 , characterised in that it contains N up to 0.2% Mn up to 2% Al up to 0.4% and rare earth metals, Y, Ca and Mg up to a total of 0.3% 5 Ti, Zr, Hf, Ta, Nb and V up to a total of 0.4% and Cu, Mo and W up to a total of 1% and impurities up to 1%. 
     
     
         11 . An alloy according to  claim 1 , characterised in that it contains Mn up to a level of 1%. 
     
     
         12 . An alloy according to  claim 1 , characterised in that its C t -value at 1000° C. is 1.10 or lower. 
     
     
         13 . An alloy according to  claim 1 , characterised in that its C t -value at 1000° C. is 1.08 or lower. 
     
     
         14 . An alloy according to  claim 1 , characterised in that the level of Cr is greater than Cr=15% and that it is less than the lower of the two values Cr=0.7*Si* (2*Si−1)−2.5*Fe+42.5 and Cr=25%. 
     
     
         15 . An alloy according to  claim 1 , characterised in that the alloy has the following composition, given in percentages by weight,
 Cr 22-24   Fe 8-10   Si 2.2-2.7   Mn 0.5-0.9   C <0.03   N 0.01-0.05   Ce <0.03   Co <0.1 Nb <0.05   impurities up to 1%   
       and in that Ni comprises the balance. 
     
     
         16 . An alloy according to  claim 1 , characterised in that the alloy has the following composition, given in percentages by weight,
 Cr 22-23   Fe 8.5-9.5   Si 2.3-2.6   Mn 0.6-0.7   C <0.02   N 0.01-0.03   Ce 0.005-0.015   Co <0.01   Nb <0.01   impurities up to 0.7%   
       in that Ni comprises the balance. 
     
     
         17 . An alloy according to  claim 14 , characterised in that its C t -value at 1000° C. is 1.07 or lower. 
     
     
         18 . An electrical heating arrangement, characterised in that its electrical resistive material is manufactured from an alloy according to  claim 1 . 
     
     
         19 . A tube element with a metal cover, characterised in that its electrical resistive material is manufactured from an alloy according to  claim 1 . 
     
     
         20 . An alloy according to  claim 4 , characterised in that the alloy contains up to 5% Co as a replacement for Ni.