초록 ▼

A chromium-iron alloy comprises in weight %, 1 to 3% C, 1 to 3% Si, up to 3% Ni, 25 to 35% Cr, 1.5 to 3% Mo, up to 2% W, 2.0 to 4.0% Nb, up to 3.0% V, up to 3.0% Ta, up to 1.2% B, up to 1% Mn and 43 to 64% Fe. In a preferred embodiment, the chromium-iron alloy comprises in weight %, 1.5 to 2.3% C, 1

A chromium-iron alloy comprises in weight %, 1 to 3% C, 1 to 3% Si, up to 3% Ni, 25 to 35% Cr, 1.5 to 3% Mo, up to 2% W, 2.0 to 4.0% Nb, up to 3.0% V, up to 3.0% Ta, up to 1.2% B, up to 1% Mn and 43 to 64% Fe. In a preferred embodiment, the chromium-iron alloy comprises in weight %, 1.5 to 2.3% C, 1.6 to 2.3% Si, 0.2 to 2.2% Ni, 27 to 34% Cr, 1.7 to 2.5% Mo, 0.04 to 2% W, 2.2 to 3.6% Nb, up to 1% V, up to 3.0% Ta, up to 0.7% B, 0.1 to 0.6% Mn and 43 to 64% Fe. The chromium-iron alloy is useful for valve seat inserts for internal combustion engines such as diesel or natural gas engines.

대표청구항 ▼

1. A chromium-iron alloy comprising in weight %: 1 to 3% C;1 to 3% Si;up to 3% Ni;25 to 35% Cr;1.5 to 3% Mo;up to 2% W;2.0 to 4.0% Nb;up to 3.0% V;up to 3.0% Ta;up to 1.2% B;up to 1% Mn;43 to 64% Fe; and comprising a ferrite-carbide matrix with spherical and/or polyhedron-shaped particles distribute

1. A chromium-iron alloy comprising in weight %: 1 to 3% C;1 to 3% Si;up to 3% Ni;25 to 35% Cr;1.5 to 3% Mo;up to 2% W;2.0 to 4.0% Nb;up to 3.0% V;up to 3.0% Ta;up to 1.2% B;up to 1% Mn;43 to 64% Fe; and comprising a ferrite-carbide matrix with spherical and/or polyhedron-shaped particles distributed throughout the ferrite-carbide matrix. 2. The chromium-iron alloy of claim 1 comprising in weight %: 1.5 to 2.3% C;1.6 to 2.3% Si;0.2 to 2.2% Ni;27 to 34% Cr;1.7 to 2.5% Mo;0.04 to 2% W;2.2 to 3.6% Nb;up to 1% V;up to 1.0% Ta;up to 0.7% B;0.1 to 0.6% Mn;43 to 64% Fe. 3. The chromium-iron alloy of claim 1, further comprising incidental impurities of one or more of Al, As, Bi, Cu, Ca, Ce, Co, Hf, Mg, N, P, Pb, S, Sn, Ti, Y and Zn with a total content of incidental impurities of 1.5 weight % or less. 4. The chromium-iron alloy of claim 1, wherein the ferrite-carbide matrix comprises a primary carbide phase having an acicular microstructure and a ferrite phase having a semi-acicular microstructure; and the spherical and/or polyhedron-shaped particles are metal carbides, metal nitrides and/or metal carbonitrides dispersed along phase boundaries of the primary carbide phase and the ferrite phase. 5. The chromium-iron alloy of claim 4, wherein the primary carbide phase is chromium-rich and molybdenum-rich; the ferrite phase is chromium-rich; and the phase boundaries of the primary carbide phase and the ferrite phase are boron-rich. 6. A valve seat insert made essentially of the chromium-iron alloy of claim 1. 7. The valve seat insert of claim 6, wherein the insert is a casting. 8. A method of manufacturing the valve seat insert of claim 6, comprising machining a piece of the chromium-iron alloy. 9. A method of manufacturing an internal combustion engine comprising inserting the valve seat insert of claim 6 in a cylinder head of the internal combustion engine. 10. The method of claim 9, wherein the engine is a diesel or natural gas engine. 11. A method of operating an internal combustion engine comprising closing a valve against the valve seat insert of claim 6 to close a cylinder of the internal combustion engine and igniting fuel in the cylinder to operate the internal combustion engine. 12. The method of claim 11, wherein the valve: (i) is a high-chromium iron-based alloy or a high-temperature, nickel-based superalloy; or(ii) the valve is hard-faced with a high temperature, wear-resistant alloy strengthened by carbides. 13. A chromium-iron alloy comprising in weight %: 1 to 3% C;1 to 3% Si;up to 3% Ni;25 to 35% Cr;1.5 to 3% Mo;up to 2% W;2.0 to 4.0% Nb;up to 3.0% V;up to 3.0% Ta;up to 1.2% B;up to 1% Mn;43 to 64% Fe; wherein the chromium-iron alloy has an as-cast bulk hardness from 40 to 56 Rockwell C; a hot hardness (HV10) from 450 to 500 at 75° F., from 280 to 300 at 1000° F., from 55 to 70 at 1600° F.; a compressive yield strength from 90 to 220 KSi at 75° F., from 70 to 130 at 1000° F.; a linear thermal expansion coefficient from 8×10−6 to 12×10−6/° C. 14. A valve seat insert made of a chromium-iron alloy comprising in weight %: 1 to 3% C;1 to 3% Si;up to 3% Ni;25 to 35% Cr;1.5 to 3% Mo;up to 2% W;2.0 to 4.0% Nb;up to 3.0% V;up to 3.0% Ta;up to 1.2% B;up to 1% Mn;43 to 64% Fe;wherein the insert exhibits a dimensional stability of less than 0.3×10−3 inch per inch of insert outside diameter (O.D.) after heating for 20 hours at 1200° F. 15. A method of making a chromium-iron alloy comprising in weight %: 1 to 3% C;1 to 3% Si;up to 3% Ni;25 to 35% Cr;1.5 to 3% Mo;up to 2% W;2.0 to 4.0% Nb;up to 3.0% V;up to 3.0% Ta;up to 1.2% B;up to 1% Mn;43 to 64% Fe; wherein: (a) the chromium-iron alloy is cast into a shaped component from a melt at a temperature from about 2700° F. to about 3000° F.; or(b) a powder of the chromium-iron alloy is pressed into a shaped component and sintered at a temperature from about 1950° F. to about 2300° F. in a reducing atmosphere, wherein the reducing atmosphere is hydrogen or a mixture of dissociated ammonia and nitrogen. 16. The method of claim 15, further comprising a high temperature tempering heat treatment at about 1325° F. for about 5 hours.