Sintered materials of austenite steel powder and turbine members

Abstract

The present invention aims to provide sintered materials of austenite steel powder each having a strength which is equivalent to or in excess of the strength of a Ni-based alloy and insusceptible to oxygen and turbine members each being composed of each sintered material. There is provided the sintered material of austenite steel powder which contains 25 to 50% Ni; 12 to 25% Cr, 3 to 6% Nb; 0.001 to 0.05% B; not more than 1.6% Ti; not more than 6% W; not more than 4.8% Mo; and not more than 0.5% Zr in percentage by mass, with a balance made up of Fe and unavoidable impurities.

What is claimed is: 
     
         1 . A sintered material of austenite steel powder containing:
 25 to 50% Ni; 12 to 25% Cr; 3 to 6% Nb; 0.001 to 0.05% B; not more than 1.6% Ti; not more than 6% W; not more than 4.8% Mo; and not more than 0.5% Zr in percentage by mass, with a balance made up of Fe and unavoidable impurities.   
     
     
         2 . A sintered material of austenite steel powder containing:
 30 to 45% Ni; 12 to 20% Cr; 3 to 5% Nb; 0.001 to 0.02% B; 0.3 to 1.3% Ti; not more than 5.5% W; not more than 2% Mo; and not more than 0.3% Zr in percentage by mass, with a balance made up of Fe and unavoidable impurities.   
     
     
         3 . A sintered material of austenite steel powder containing:
 30 to 40% Ni; 15 to 20% Cr; 3.5 to 4.5% Nb; 0.001 to 0.02% B; 0.5 to not more than 1.1% Ti; not more than 5.5% W; and not more than 0.3% Zr in percentage by mass, with a balance made up of Fe and unavoidable impurities.   
     
     
         4 . The sintered material of austenite steel powder according to  claim 1 , wherein an average particle diameter of the sintered material of austenite steel powder is 10 to 300 μm. 
     
     
         5 . The sintered material of austenite steel powder according to  claim 1 , wherein a Laves phase precipitates on a crystal grain boundary of the sintered material of austenite steel powder. 
     
     
         6 . The sintered material of austenite steel powder according to  claim 5 , wherein the Laves phase is made up of Fe 2 Nb. 
     
     
         7 . A turbine member comprising the sintered material of austenite steel powder according to  claim 1 . 
     
     
         8 . The turbine member according to  claim 7 , wherein the turbine member is a turbine valve casing or a turbine disc. 
     
     
         9 . Austenite steel powder containing 25 to 50% Ni; 12 to 25% Cr; 3 to 6% Nb; 0.001 to 0.05% B; not more than 1.6% Ti; not more than 6% W; not more than 4.8% Mo; and not more than 0.5% Zr in percentage by mass, with a balance made up of Fe and unavoidable impurities. 
     
     
         10 . Austenite steel powder containing 30 to 45% Ni; 12 to 20% Cr; 3 to 5% Nb; 0.001 to 0.02% B; 0.3 to 1.3% Ti; not more than 5.5% W; not more than 2% Mo; and not more than 0.3% Zr in percentage by mass, with a balance made up of Fe and unavoidable impurities. 
     
     
         11 . Austenite steel powder containing 30 to 40% Ni; 15 to 20% Cr; 3.5 to 4.5% Nb; 0.001 to 0.02% B;  0 . 5  to not more than 1.1% Ti; not more than 5.5% W; and not more than 0.3% Zr in percentage by mass, with a balance made up of Fe and unavoidable impurities 
     
     
         12 . The austenite steel powder according to  claim 9 , wherein an average particle diameter of the austenite steel powder is not more than 250 μm.