Internal nitridation of cobalt-base superalloys
First Claim
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1. A method of strengthening cobalt-base superalloys by internal nitridation of substantially the entire volume of said alloys, which comprises the steps of:
- heating a cobalt-base alloy containing at least 33% cobalt as the major constituent, chromium, up to 25% nickel, up to 0.15% carbon, from 1 to 3% of nitride forming elements from the group consisting of titanium, vanadium, niobium, and tantalum, balance residuals and those elements which enhance the properties of cobalt-base alloys, at a temperature of from 1600°
to 2500°
F in a nitrogen-bearing atmosphere substantially free of moisture and oxygen, and diffusing nitrogen from said atmosphere into and throughout said alloy for a period of time sufficient to form nitrides having an interparticle spacing of less than 10 microns, said nitrides being from the group consisting of titanium nitride, vanadium nitride, niobium nitride and tantalum nitride, said nitrides being distributed substantially throughout said nitrided alloy;
said cobalt base alloy being less than 25 mils thick.
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Abstract
A method of internally nitriding and thereby strengthening cobalt-base superalloys having at least 33% cobalt, up to 0.15% carbon, no more than 25% nickel and from 1 to 3% of nitride forming elements from the group consisting of titanium, vanadium, niobium, tantalum and zirconium. The method comprises the steps of: heating the cobalt-base alloy at a temperature of from 1600° to 2500° F in a nitrogen-bearing atmosphere substantially free of moisture and oxygen, and diffusing nitrogen from said atmosphere into and throughout said alloy for a period of time sufficient to form nitrides having an interparticle spacing of less than 10 microns.
21 Citations
13 Claims
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1. A method of strengthening cobalt-base superalloys by internal nitridation of substantially the entire volume of said alloys, which comprises the steps of:
- heating a cobalt-base alloy containing at least 33% cobalt as the major constituent, chromium, up to 25% nickel, up to 0.15% carbon, from 1 to 3% of nitride forming elements from the group consisting of titanium, vanadium, niobium, and tantalum, balance residuals and those elements which enhance the properties of cobalt-base alloys, at a temperature of from 1600°
to 2500°
F in a nitrogen-bearing atmosphere substantially free of moisture and oxygen, and diffusing nitrogen from said atmosphere into and throughout said alloy for a period of time sufficient to form nitrides having an interparticle spacing of less than 10 microns, said nitrides being from the group consisting of titanium nitride, vanadium nitride, niobium nitride and tantalum nitride, said nitrides being distributed substantially throughout said nitrided alloy;
said cobalt base alloy being less than 25 mils thick. - View Dependent Claims (2, 3, 4, 5, 6, 7)
- heating a cobalt-base alloy containing at least 33% cobalt as the major constituent, chromium, up to 25% nickel, up to 0.15% carbon, from 1 to 3% of nitride forming elements from the group consisting of titanium, vanadium, niobium, and tantalum, balance residuals and those elements which enhance the properties of cobalt-base alloys, at a temperature of from 1600°
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8. A method of strengthening cobalt-base superalloys by internal nitridation of substantially the entire volume of said alloys, which comprises the steps of:
- heating a cobalt-base alloy containing at least 33% cobalt as the major constituent, chromium, up to 25% nickel, up to 0.15% carbon, from 1 to 3% of nitride forming elements from the group consisting of titanium, vanadium, niobium, tantalum and zirconium, balance residuals and those elements which enhance the properties of cobalt-base alloys, at a temperature of from 1600°
to 2500°
F in a nitrogen-bearing atmosphere substantially free of moisture and oxygen, and diffusing nitrogen from said atmosphere into and throughout said alloy for a period of time sufficient to form nitrides having an interparticle spacing of less than 10 microns, said nitrides being from the group consisting of titanium nitride, vanadium nitride, niobium nitride, tantalum nitride and zirconium nitride, said nitrides being distributed substantially throughout said nitrided alloy;
said cobalt base alloy being less than 25 mils thick. - View Dependent Claims (9, 10, 11, 12, 13)
- heating a cobalt-base alloy containing at least 33% cobalt as the major constituent, chromium, up to 25% nickel, up to 0.15% carbon, from 1 to 3% of nitride forming elements from the group consisting of titanium, vanadium, niobium, tantalum and zirconium, balance residuals and those elements which enhance the properties of cobalt-base alloys, at a temperature of from 1600°
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Current AssigneePittsburgh National Bank (The PNC Financial Services Group, Inc.)
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Original AssigneeAllegheny Ludlum Corporation (Allegheny Technologies Incorporated)
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InventorsKindlimann, Lynn E., Hartline, Albert G. III
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Primary Examiner(s)Satterfield, Walter R.
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Application NumberUS05/689,402Time in Patent Office456 DaysField of Search148/20.3, 148/16.6, 148/38, 75/170, 75/171US Class Current148/207CPC Class CodesC23C 8/24 Nitriding
