Patent US4071382A successfully refreshed from Google Patents.
US4071382A
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Method for case hardening powdered metal parts
Assignee: Surface Combustion Corp
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Filing: 1976-07-22
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Granted: 1978-01-31
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Expires: 1996-07-22
Abstract
Abstract A method and apparatus is provided for case hardening a porous, powdered metal part by means of a gaseous atmosphere without incurring excessive embrittlement or unacceptable physical distortion of the part. Prior to subjecting the part to the case hardening gaseous atmosphere, the part is heated in an oxidizing atmosphere for a time period sufficent to form oxides of iron which substantially fill the pores at the surface of the part. When the part is later subject to the case hardening gaseous atmosphere, at least one element of the gaseous atmosphere reacts with the oxides of iron and Fe to produce hardenable iron compounds.
Inventors
- 👤 Joseph A. Riopelle
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 11:49
CPC Classifications
B; B22; B22F; B22F3/00; B22F3/24; B22F3/10; B22F3/11; B22F3/1143
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
91 words
A process for case hardening a powdered metal part having a porous, sintered body of a heat treatable steel composition comprised primarily of Fe, said process comprising the steps of: heating said part in an oxidizing atmosphere for a time period sufficient to form oxides of iron substantially filling the pores of said part at the surface of said part; and subjecting said part to a predetermined gaseous atmosphere at a predetermined temperature and time sufficient to react with said oxides of iron and said Fe to produce hardenable iron compounds.
Claim 2
Dependent Claim
91 words
A process for case hardening a powdered metal part having a porous, sintered body of a heat treatable steel composition comprised primarily of Fe, said process comprising the steps of: heating said part in an oxidizing atmosphere for a time period sufficient to form oxides of iron substantially filling the pores of said part at the surface of said part; and subjecting said part to a predetermined gaseous atmosphere at a predetermined temperature and time sufficient to react with said oxides of iron and said Fe to produce hardenable iron compounds.
Claim 3
Dependent Claim
34 words
The process of claim 1 wherein said parts are initially subjected after oxidation to a neutral carrier gas atmosphere to which is added a gas principally responsible for hardening the case of said part.
Claim 4
Dependent Claim
30 words
The process of claim 1 wherein said heating step occurs at a temperature range of 800° to 1100° F. for a period of time from 30 minutes to 120 minutes.
Claim 5
Dependent Claim
18 words
The process of claim 3 wherein said atmosphere includes ammonia and said case is formed of iron nitride.
References Cited (Backward Citations)
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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) | 1981-01-30 | 1981-08-01 | 1982-01-31 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1985-01-30 | 1985-08-01 | 1986-01-31 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1989-01-30 | 1989-08-01 | 1990-01-31 | $7700.00 | Window Closed / Lapsed |