Alloys with high corrosion resistance for engine valve applications

Abstract

Low cost alloys resistant to mechanical requirements related to high temperatures, resistant to corrosion, with high workability and which meet different requirements in the conditions for application in either exhaust or intake valves for internal combustion engines. The main features of the alloys is the precipitation of Ni 3 Nb in its microstructure. In percentage, its mass consists of: 0.01 to 0.15% C, up to 3.0% Mn, up to 1.0% Si, 18.0 to 25.0% Cr, 25.0 to 49.0% Ni, up to 0.50% Mo, up to 0.50% W, up to 0.50% V, up to 5.0% Cu, 1.0 to 3.0% Al, 0.5 to 2.5% Ti, 1.0 to 6.0% Nb, 0.001 to 0.02% B, 0.001 to 0.10% Zr, up to 2.0% Co, where (Ni+Co) is not higher than 50.0% in mass, nor lower than 25% in mass. As for the ration Al/Ti, it is lower than 2.0. The rest is made of iron and impurities inevitable to the Alloy manufacture procedure.

1 . A Fe—Ni—Cr alloy for internal combustion engine valves, presenting a chemical composition of elements comprising,
 C, Mn, Si, Cr, Ni, Mo, W, V, Al, Ti, Nb, B, Zr, Cu, Co,   
     
     
         2 . The Fe—Ni—Cr alloy according to  claim 1 , presenting a chemical composition of elements comprising, in percentage in mass,
 up to 0.15% C,   up to 3.0% Mn,   up to 1.0% Si,   18.0 to 25.0% Cr,   25.0 to 49.0% Ni,   up to 1.0% Mo,   up to 1.0% W,   up to 1.0% V,   1.0 to 3.0% Al,   0.5 to 2.5% Ti,   1.0 to 6.0% Nb,   0.001 to 0.02% B,   0.001 to 0.1% Zr,   up to 1.0% Cu,   up to 2.0% Co,   where (Ni+Co) is not higher than 50.0% in mass, nor lower than 25% in mass, and the ratio of percentages in mass Ti:Al is lower than 2:1.   
     
     
         3 . The Fe—Ni—Cr alloy according to  claim 1 , presenting a chemical composition of elements comprising, in percentage in mass,
 up to 0.15% C,   up to 3.0% Mn,   up to 1.0% Si,   18.5 to 25.0% Cr,   27.0 to 49.0% Ni,   up to 0.50% Mo,   up to 0.50% W,   up to 0.50% V,   1.0 to 3.0% Al,   1.0 to 2.0% Ti,   1.0 to 6.0% Nb,   0.001 to 0.02% B,   0.001 to 0.1% Zr,   up to 0.5% Cu,   up to 2.0% Co,   where (Ni+Co) is not higher than 50.0% in mass, nor lower than 25% in mass, and the ratio of percentages in mass Ti:Al is lower than 2:1.   
     
     
         4 . The Fe—Ni—Cr alloy according to  claim 1 , presenting a chemical composition of elements comprising, in percentage in mass, up to 0.10% C,
 0.05 to 1.0% Mn,   0.05 to 1.0% Si,   18.6 to 25.0% Cr,   27.0 to 49.0% Ni,   up to 0.50% Mo,   up to 0.50% W,   up to 0.50% V,   1.0 to 3.0% Al,   0.5 to 1.5% Ti,   1.0 to 4.0% Nb,   0.001 to 0.02% B,   0.001 to 0.1% Zr,   up to 0.5% CU,   up to 2.0% Co,   where (Ni+Co) is not higher than 50.0% in mass, nor lower than 25% in mass, and the ratio of percentages in mass Ti:Al is lower than 2:1.   
     
     
         5 . The Fe—Ni—Cr alloy according to  claim 1 , presenting a chemical composition of elements comprising, in percentage in mass,
 0.01 to 0.10% C,   0.05 to 1.0% Mn,   0.05 to 1.0% Si,   18.6 to 23.0% Cr,   30.0 to 40.0% Ni,   up to 0.50% Mo,   up to 0.50% W,   up to 0.50% V,   1.0 to 3.0% Al,   0.5 to 1.5% Ti,   1.0 to 4.0% Nb,   0.001 to 0.02% B,   0.001 to 0.1% Zr,   up to 0.5% Cu,   up to 2.0% Co,   where (Ni+Co) is not higher than 50.0% in mass, nor lower than 25% in mass, and the ratio of percentages in mass Ti:Al is lower than 1.5:1.   
     
     
         6 . The Fe—Ni—Cr alloy according to  claim 1 , presenting a chemical composition of elements comprising, in percentage in mass,
 0.01 to 0.10% C,   0.05 to 1.0% Mn,   0.05 to 1.0% Si,   18.6 to 23.0% Cr,   30.0 to 40.0% Ni,   up to 0.50% Mo,   up to 0.50% W,   up to 0.50% V,   1.5 to 3.0% Al,   0.5 to 1.5% Ti,   1.0 to 3.0% Nb,   0.001 to 0.02% B,   0.001 to 0.1% Zr,   up to 0.2% CU,   up to 2.0% Co,   where (Ni+Co) is not higher than 50.0% in mass, nor lower than 25% in mass and the ratio of percentages in mass Ti:Al is lower than 1.5:1.   
     
     
         7 . The Fe—Ni—Cr alloy according to  claim 1 , presenting a chemical composition of elements comprising, in percentage in mass, 0.01 to 0.10% C,
 0.05 to 1.0% Mn,   0.05 to 1.0% Si,   18.6 to 23.0% Cr,   35.0 to 40.0% Ni,   up to 0.50% Mo,   up to 0.50% W,   up to 0.50% V,   1.0 to 3.0% Al,   0.5 to 1.5% Ti,   1.0 to 4.0% Nb,   0.001 to 0.02% B,   0.001 to 0.1% Zr,   up to 0.2% Cu,   up to 2.0% Co,   where (Ni+Co) is not higher than 50.0% in mass, nor lower than 25% in mass, and the ratio of percentages in mass Ti:Al is lower than 1.5:1.   
     
     
         8 . The Fe—Ni—Cr alloy according to  claim 1 , presenting a chemical composition of elements comprising, in percentage in mass,
 0.01 to 0.10% C,   0.05 to 1.0% Mn,   0.05 to 1.0% Si,   18.6 to 23.0% Cr,   30.0 to 40.0% Ni,   up to 0.50% Mo,   up to 0.50% W,   up to 0.50% V,   1.5 to 3.0% Al,   0.5 to 1.5% Ti,   1.0 to 3.0% Nb,   0.001 to 0.02% B,   0.001 to 0.1% Zr,   up to 0.1% Cu,   up to 2.0% Co,   where (Ni+Co) is not higher than 50.0% in mass, nor lower than 25% in mass, and the ratio of percentages in mass Ti:Al is lower than 1.2:1.   
     
     
         9 . The Fe—Ni—Cr alloy according to  claim 1 , where the value of M, calculated by the equation below, follows the ratio 2.0≦M≦15.0;
     M =(Nb)+2(Ti)*(percentage in mass)   
     
     
         10 . The Fe—Ni—Cr alloy according to  claim 1 , where the value of M, calculated by the equation below, follows the ratio 5.0≦M≦11.0;
     M =(Nb)+2(Ti)*(percentage in mass)   
     
     
         11 . The Fe—Ni—Cr alloy according to  claim 1 , where residual impurities from the manufacture process, such as Ca and Mg, are not in excess of 0.03% in mass; 
     
     
         12 . The Fe—Ni—Cr alloy according to  claim 1 , where impurities are controlled, in order to achieve the maximum of 0.02% in mass of P and the maximum of 0.0050 of S; 
     
     
         13 . The Fe—Ni—Cr alloy according to  claim 1 , produced via air induction furnace, vacuum induction furnace or arc electric furnace, by processes of conventional casting, continuous casting or processes which involve alloy fragmentation and aggregation, among them, powder metallurgy, powder injection, and spray formation, resulting in end product obtained through hot formation, cold formation, or products used directly under the “as cast” condition; 
     
     
         14 . The Fe—Ni—Cr alloy according to  claim 1 , applied as exhaust valves or intake valves of internal combustion engines; 
     
     
         15 . The Fe—Ni—Cr alloy according to  claim 1 , applied as components, tools or structural, static or dynamic parts, in applications which demand resistance at high temperatures, resistance to creep, and resistance to abrasion;