Austenitic fe-cr-ni alloy for high temperature

Abstract

An austenitic alloy for high temperature use, particularly for use in resistance heating elements. The alloy includes primarily the elements Fe, Ni, and Cr, and it has the following main composition, given in weight %, Ni 38-48, Cr 18-24, Si 1.0-1.9, C <0.1, and the balance Fe. The alloy provides good hot form stability, good oxidation resistance, and a relatively high electrical resistance coupled with a low change in resistance as a function of temperature.

What is claimed is: 
     
         1 . An Fe—Ni—Cr alloy for high temperature use having a composition comprising:
 Ni 44-46 weight-%; 
 Cr 20-22 weight-%; 
 Si 1.0-1.9 weight-%; 
 N<0.15 weight-%; 
 Ce 0.01-0.04 weight-%; 
 C <0.1 weight-%; 
 impurities up to 2 weight-%; and 
 Fe balance. 
 
     
     
         2 . The alloy according to  claim 1 , wherein the composition further includes:
 Mn less than 2 weight-%; and   Al, C, Ca, N, Ti, Zr, Hf, Ta, Nb, V, Mg, Ta, W, Ce and Rare Earth Elements together are less than approximately 7 weight-%.   
     
     
         3 . The alloy according to  claim 2 , wherein the composition includes Cr in an amount between (−0.1Ni+23) and (−0.2667Ni+36) (weight-%) and Si in an amount between 0.8 and (−0.0133Ni+2.2) (weight-%). 
     
     
         4 . The alloy according to  claim 1 , wherein the composition includes Cr in an amount between (−0.1Ni+23) and (−0.2667Ni+36) (weight-%) and Si in an amount between 0.8 and (−0.0133Ni+2.2) (weight-%). 
     
     
         5 . The alloy according to  claim 1 , wherein the composition includes Cr in an amount between (−0.1Ni+24) and (−0.1667Ni+30) (weight-%) and Si in an amount between 1.0 and (−0.01Ni+1.9) (weight-%),
 wherein the alloy contains up to 5 weight-% Co as substitute of Ni, and 
 wherein the composition further includes:
 Mn up to 2 weight-%, 
 Al up to 0.6 weight-%, 
 Rare Earth Elements, Y and Caup to 0.2 weight-%, 
 Ti, Zr, Hf, Ta, Nb and Vup to 0.4 weight-% in total, 
 S<50 wt ppm, and 
 other elements <2 weight-% in total. 
 
 
     
     
         6 . The alloy according to  claim 1 , wherein the composition further includes:
 Si 1.0-1.5 weight-%,   Al <0.6 weight-%,   Mn <1 weight-%,   S <50 wt ppm,   elements belonging to the group Ti, Zr, Hf, Y, Rare Earth Elements (Lantanoid group), Ca, Mg and Taless than 0.5 weight-% in total,   elements belonging to the group Mo, Co, Ta, Wless than 5 weight-%,   elements belonging to the group Ti, Zr, Hf, Ta, Nb and V less than 0.4 weight-%, and   other elements <2 weight-% in total.   
     
     
         7 . The alloy according to  claim 1 , wherein the composition includes Si in an amount of 1.0-1.5 weight-% and C in an amount of 0.02 weight-%.