US4793871A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method of improving surface wear qualities of metal components
Assignee: SENIOR HEAT TREATMENT Ltd
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Filing: 1987-04-10
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Granted: 1988-12-27
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Expires: 2007-04-10
Abstract
Abstract An epsilon iron nitride surface layer of high surface wear resistance is formed on a steel component by gas nitriding or nitrocarburising and, according to the invention, includes the preliminary step of heating the component to the nitriding temperature in an atmosphere which is inert to the metal of the component.
Inventors
- 👤 Cyril Dawes
- 👤 Donald F. Tranter
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 08:54
CPC Classifications
C; C23; C23C; C23C8/00; C23C8/40; C23C8/52; C23C8/54; C23C8/56; C23C8/06; C23C8/28; C23C8/30; C23C8/32; C23C8/02; C23C8/08; C23C8/24; C23C8/26
Claims Analysis
Total Claims: 14
Claim 1
Independent Claim
131 words
A method of subjecting a steel component made of a non-alloy or fine grained steel to a hardening treatment to increase the surface wear resistance thereof, comprising the steps of: (a) disposing the component in a sealable vessel; (b) deliberately excluding from the atmosphere in the vessel all elements in gaseous form which will cause the formation of a porous epsilon iron nitride layer thereon; (c) heating the component in the vessel to a treatment temperature; and then (d) exposing the component, heated to the treatment temperature at atmospheric pressure, to a gaseous nitriding or nitrocarburizing atmosphere for a period until there is formed thereon an epsilon iron nitride layer which is wear resistant, has a hardness of about 800 to 1000 HV, is non porous, and extends 18 micron deep.
Claim 2
Independent Claim
131 words
A method of subjecting a steel component made of a non-alloy or fine grained steel to a hardening treatment to increase the surface wear resistance thereof, comprising the steps of: (a) disposing the component in a sealable vessel; (b) deliberately excluding from the atmosphere in the vessel all elements in gaseous form which will cause the formation of a porous epsilon iron nitride layer thereon; (c) heating the component in the vessel to a treatment temperature; and then (d) exposing the component, heated to the treatment temperature at atmospheric pressure, to a gaseous nitriding or nitrocarburizing atmosphere for a period until there is formed thereon an epsilon iron nitride layer which is wear resistant, has a hardness of about 800 to 1000 HV, is non porous, and extends 18 micron deep.
Claim 3
Dependent Claim
34 words
A method as recited in claim 1 wherein steps (b) and (c) are practiced by drawing a vacuum in the vessel and heating the component to the treatment temperature while the vacuum is maintained.
Claim 4
Dependent Claim
42 words
A method as recited in claim 1 wherein steps (b) and (c) are practiced by supplying a gaseous atmosphere which is inert to the steel component to the vessel, and heating the component to the treatment temperature in the inert gaseous atmosphere.
Claim 5
Dependent Claim
28 words
A method as recited in claim 1 wherein the steel component is formed of a non-alloy steel or fine grained structural steel containing niobium and vanadium or titanium.
Claim 6
Dependent Claim
27 words
A method as recited in claim 3 wherein the inert gas forming the inert gaseous atmosphere is selected from the group consisting essentially of nitrogen and argon.
Claim 7
Dependent Claim
29 words
A method as recited in claim 1 wherein steps (a) through (c) are practiced utilizing a sealable metal retort fitted with an atmosphere circulation fan as the sealable vessel.
Claim 8
Dependent Claim
24 words
A method as recited in claim 6 wherein step (c) is practiced by forced convective heating utilizing the fan of the sealable metal retort.
Claim 9
Dependent Claim
19 words
A method according to claim 6 wherein the method is practiced by mounting the retort in a vacuum furnace.
Claim 10
Dependent Claim
55 words
A method as recited in claim 1 wherein step (d) is practiced by supplying as the nitriding or nitrocarburising gaseous atmosphere gases selected from the group consisting essentially of: ammonia with an addition of carbon monoxide, water vapor, air or oxygen; and a gaseous mixture of endothermic gas; and a gaseous mixture of exothermic gas.
Claim 11
Dependent Claim
49 words
A method as recited in claim 2, wherein step (b) is practiced by drawing a vacuum in the vessel to about 10 -1 m bar, the vessel is then filled to atmospheric pressure with nitrogen and then step (c) is practiced while the component is in the nitrogen atmosphere.
Claim 12
Dependent Claim
24 words
A method as recited in claim 9 wherein step (d) is practiced at a temperature of from about 540° C. to about 740° C.,
Claim 13
Dependent Claim
15 words
A method as recited in claim 11, wherein the treatment temperature is about 610° C.
Claim 14
Dependent Claim
16 words
A method as recited in claim 11 wherein step (d) is practiced for about one hour.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1991-12-27 | 1992-06-27 | 1992-12-27 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1995-12-27 | 1996-06-27 | 1996-12-27 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1999-12-27 | 2000-06-27 | 2000-12-27 | $7700.00 | Window Closed / Lapsed |