Heat-resistant steel

Abstract

A high temperature corrosion resistant stainless steel having a composition (by weight) of: C≦0.2%, but more than zero, N≦0.1% but more than zero, O≦0.1% but more than zero, Si≦0.4% but more than zero, Al<0.5% but more than zero, Mn≦0.5% but more than zero, Cr 20 to 25%, Ni≦2.0% but more than zero, Zr+Hf 0.01 to 0.1%, Ti≦0.5% but more than zero, Mo+W≦2.5% but more than zero, Nb+Ta≦1.25% but more than zero, V≦0.5% but more than zero, and balance of Fe and naturally occurring impurities and not more than 0.010% of S impurity. This steel is particularly suitable for the manufacturing of interconnects in solid oxide fuel cells.

1 . A high temperature corrosion resistant stainless steel, consisting essentially of (by weight): 
 C≦0.2%, but more than zero;    N≦0.1% but more than zero;    O≦0.1% but more than zero;    Si≦0.4% but more than zero;    Al<0.5% but more than zero;    Mn≦0.5% but more than zero;    Cr 20 to 25%;    Ni≦2.0% but more than zero;    Zr+Hf 0.001 to 0.1%;    Ti≦0.5% but more than zero;    Mo+W≦2.5% but more than zero;    Nb+Ta≦1.25% but more than zero;    V≦0.5% but more than zero; and    balance of Fe and naturally occurring impurities and not more than 0.010% of S impurity.    
   
   
       2 . The stainless steel according to  claim 1 , wherein the stainless steel has a weight gain of less than 1.5 mg/cm 2  when oxidized in air or air +1% H 2 O at 850° C. after 1000 hours, without any spallation of the oxide scale.  
   
   
       3 . The stainless steel according to  claim 2 , wherein the stainless steel has a linear thermal expansion coefficient of more than 11.5×10 −6 (° C. −1 ) but less than 13.0×10 −6 (° C −1 ) in the temperature range of 30 to 900° C.  
   
   
       4 . The stainless steel according to  claim 1 , wherein the stainless steel has a linear thermal expansion coefficient of more than 11.5×10 −6 (° C. −1 ) but less than 13.0×10 −6 (° C. −1 ) in the temperature range of 30 to 900° C.  
   
   
       5 . The stainless steel according to  claim 1 , wherein the stainless steel has a thermal expansion mismatch (TEM) with an electro-active ceramic material in a solid oxide fuel cell of less than ±15%.  
   
   
       6 . The stainless steel according to  claim 1 , wherein the stainless steel is suitable for application as an interconnect or a bipolar plate material in Solid Oxide Fuel Cells.  
   
   
       7 . The stainless steel according to  claim 1 , wherein the stainless steel is suitable for application as a catalytic converter in automobile applications.  
   
   
       8 . The stainless steel according to  claim 1 , wherein the stainless steel has an Area Specific Resistance of less than 50 mΩ cm 2  after 1000 hours on both an anode side and a cathode side of a Solid Oxide Fuel Cell.  
   
   
       9 . The alloy according to  claim 8 , wherein an increment of the Area Specific Resistance is not greater than 10 mΩ cm 2  per 1000 hours.  
   
   
       10 . A solid oxide fuel cell comprising the stainless steel according to  claim 1 .  
   
   
       11 . A catalytic converter intended for the automobile industry, comprising the stainless steel according to  claim 1 .  
   
   
       12 . A high temperature corrosion resistant stainless steel consisting essentially of (by weight): 
 C≦0.1% but more than zero;    N≦0.1% but more than zero;    O≦0.1% but more than zero;    Si≦0.4% but more than zero;    Al<0.4% but more than zero;    Mn≦0.4% but more than zero;    Cr 20 to 25%;    Ni≦1.0% but more than zero;    Zr 0.001 to 0.1%;    Ti≦0.4% but more than zero;    Mo≦2.5% but more than zero;    Nb≦1.25% but more than zero;    V≦0.1% but more than zero; and    balance of Fe and naturally occurring impurities and not more than 0.010% of S impurity.    
   
   
       13 . The stainless steel according to  claim 12 , wherein the stainless steel has a weight gain of less than 1.5 mg/cm 2  when oxidized in air or air +1% H 2 O at 850° C. after 1000 hours, without any spallation of the oxide scale.  
   
   
       14 . The stainless steel according to  claim 13 , wherein the stainless steel has a linear thermal expansion coefficient of more than 11.5×10 −6 (° C. −1 ) but less than 13.0×10 −6 (° C. −1 ) in the temperature range of 30 to 900° C.  
   
   
       15 . The stainless steel according to  claim 12 , wherein the stainless steel has a linear thermal expansion coefficient of more than 11.5×10 −6 (° C. −1 ) but less than 13.0×10 −6 (° C. −1 ) in the temperature range of 30 to 900° C.  
   
   
       16 . The stainless steel according to  claim 12 , wherein the stainless steel has a thermal expansion mismatch (TEM) with an electro-active ceramic material in a solid oxide fuel cell of less than ±15%.  
   
   
       17 . The stainless steel according to  claim 12 , wherein the stainless steel is suitable for application as an interconnect or a bipolar plate material in Solid Oxide Fuel Cells.  
   
   
       18 . The stainless steel according to  claim 12 , wherein the stainless steel is suitable for application as a catalytic converter in automobile applications.  
   
   
       19 . The stainless steel according to  claim 12 , wherein the stainless steel has an Area Specific Resistance of less than 50 mΩ cm 2  after 1000 hours on both an anode side and a cathode side of a Solid Oxide Fuel Cell.  
   
   
       20 . The stainless steel according to  claim 19 , wherein an increment of the Area Specific Resistance is not greater than 10 mΩ cm 2  per 1000 hours.  
   
   
       21 . A solid oxide fuel cell comprising the stainless steel according to  claim 12 .  
   
   
       22 . A catalytic converter intended for the automobile industry, comprising the stainless steel according to  claim 12.