NICKEL BASED ALLOY USEFUL FOR VALVE SEAT INSERTS
Disclosed herein is a nickel based alloy comprising, in weight percentage: carbon from about 0.5 to about 1.5; chromium from about 25 to about 35; tungsten from about 12 to about 18; iron from about 3.5 to about 8.5; molybdenum from about 1 to about 8; manganese up to about 0.50; silicon up to about 1.0; and the balance nickel and incidental impurities. The alloy is suitable for valve seat insert applications in internal combustion engines.
1 . A nickel based alloy comprising, in weight percentage: carbon from about 0.5 to about 1.5; chromium from about 25 to about 35; tungsten from about 12 to about 18; iron from about 3.5 to about 8.5; molybdenum from about 1 to about 8; manganese up to about 0.50; silicon up to about 1.0; nickel from about 30 to about 45 and incidental impurities.
2 . The alloy of claim 1 , wherein the alloy comprises about 0.95 to about 1.30 weight percent carbon.
3 . The alloy of claim 1 , wherein the alloy comprises about 28.5 to about 30.5 weight percent chromium.
4 . The alloy of claim 1 , wherein the alloy comprises at least about 14.0 weight percent tungsten.
5 . The alloy of claim 1 , wherein the alloy comprises at least about 5.0 weight percent iron and at most about 7.0 weight percent iron.
6 . The alloy of claim 1 , wherein the alloy comprises about 4.5 weight percent molybdenum.
7 . The alloy of claim 1 , wherein the alloy comprises at most about 1.3 weight percent carbon.
8 . The alloy of claim 1 , wherein the alloy comprises at most about 32.0 weight percent chromium.
9 . The alloy of claim 1 , wherein the alloy comprises at most about 16.0 weight percent tungsten.
10 . The alloy of claim 1 , wherein the alloy comprises about 40 to 42 weight percent nickel.
11 . The alloy of claim 1 , wherein the relative concentration of Cr, Ni and W is such that a three-phase eutectic composition forms at a temperature of about 800° C.
12 . The alloy of claim 1 , wherein the alloy consists essentially of, in weight percentage: carbon from about 0.95 to about 1.3; chromium from about 28.5 to about 31.5; tungsten from about 14.5 to about 15.5; iron from about 5.25 to about 8.25; molybdenum from about 4.35 to about 4.95; manganese from about 0.25 to about 0.5; silicon from about 0.15 to about 0.6; vanadium up to about 0.5, cobalt up to about 0.5, sulfur up to about 0.03, phosphorus up to about 0.03, and nickel from about 38 to about 42 and incidental impurities.
13 . The alloy of claim 1 , wherein said alloy is a casting.
14 . The alloy of claim 12 , wherein said alloy is a casting.
15 . The alloy of claim 1 , wherein said alloy is a valve seat insert for an internal combustion engine.
16 . The alloy of claim 1 , wherein the alloy has an as-cast microstructure comprising a wear resistant matrix of spheroidal eutectic domains free of coarse primary carbides.
17 . A valve seat insert for use in an internal combustion engine, said valve seat insert made of an alloy consisting essentially of in weight percent: carbon from about 0.5 to about 1.5; chromium from about 25 to about 35; tungsten from about 12 to about 18; iron from about 3.5 to about 8.5; molybdenum from about 1 to about 8; manganese up to about 0.5; silicon up to about 1.0; and the balance nickel and incidental impurities.
18 . The valve seat insert of claim 17 , wherein the valve seat insert is a casting.
19 . The valve seat insert of claim 17 , wherein the alloy consists essentially of carbon from about 0.95 to about 1.3; chromium from about 28.5 to about 31.5; tungsten from about 14.5 to about 15.5; iron from about 5.25 to about 8.25; molybdenum from about 4.35 to about 4.95; manganese from about 0.25 to about 0.5; silicon from about 0.15 to about 0.6; total of vanadium and cobalt not exceeding 0.5, sulfur not exceeding 0.03, phosphorus not exceeding 0.03, and the balance nickel and incidental impurities.
20 . The valve seat insert of claim 17 , having a hardness of about 48 to about 52 Rockwell C.