US4880477A
Expired / Lapsed
US
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Process of making an austempered ductile iron article
Assignee: Textron IPMP LP
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Filing: 1988-06-14
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Granted: 1989-11-14
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Expires: 2008-06-14
Abstract
Abstract An austempered ductile iron alloy with a mixed austenitic-bainitic structure is made by a method which enables the iron to withstand high cyclical stresses while having a high resistance to abrasion. Articles such as automobile roller-follower camshafts that are made from the iron alloy may have portions thereof selectively austempered to reduce the overall cost and time required to manufacture the article.
Inventors
- 👤 William J. Hayes
- 👤 Harry A. Matrone
- 👤 Philip D. Johnson
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-06 10:17
CPC Classifications
C; C21; C21D; C21D1/00; C21D1/18; C21D1/19; C21D1/20; C21D5/00; C21D9/00; C21D9/30; Y; Y10; Y10T; Y10T74/00; Y10T74/21; Y10T74/2101
Claims Analysis
Total Claims: 24
Claim 1
Independent Claim
148 words
A process of making an austempered ductile iron article having selected portions thereof hardened and other portions unhardened, comprising: casting an article from a cast iron composition including, by weight, 3.40% to 3.90% carbon, 1.90% to 2.70% silicon, up to 1.40% manganese, up to 1.5% molybdenum, up to 0.08% phosphorus, up to 2.0% copper and a balance of iron; and austenitizing the selected portions only of the article in non-austempered condition at a first temperature in a range of 1420° F and 2100° F for a period of one second to 100 seconds; quenching the article to a second temperature of 450° F to 850° F within 180 seconds; tempering the article at said second temperature for a period of 10 minutes to 240 minutes; and cooling the article to ambient temperature, whereby a layer of austempered ductile iron is formed at the selected portions of the article.
Claim 2
Dependent Claim
148 words
A process of making an austempered ductile iron article having selected portions thereof hardened and other portions unhardened, comprising: casting an article from a cast iron composition including, by weight, 3.40% to 3.90% carbon, 1.90% to 2.70% silicon, up to 1.40% manganese, up to 1.5% molybdenum, up to 0.08% phosphorus, up to 2.0% copper and a balance of iron; and austenitizing the selected portions only of the article in non-austempered condition at a first temperature in a range of 1420° F and 2100° F for a period of one second to 100 seconds; quenching the article to a second temperature of 450° F to 850° F within 180 seconds; tempering the article at said second temperature for a period of 10 minutes to 240 minutes; and cooling the article to ambient temperature, whereby a layer of austempered ductile iron is formed at the selected portions of the article.
Claim 3
Dependent Claim
20 words
A process according to claim 1 wherein said first temperature is in the range of 1500° F to 2000° F.
Claim 4
Dependent Claim
24 words
A process according to claim 1 wherein said article is held at said first temperature for a period of 30 seconds to 100 seconds.
Claim 5
Dependent Claim
35 words
A process according to claim 1 wherein said article is subjected to a delay of not more than 60 seconds between the steps of austenitizing at said first temperature and quenching at said second temperature.
Claim 6
Dependent Claim
22 words
A process according to claim 4 wherein the duration of said delay is in the range of one second to 10 seconds.
Claim 7
Dependent Claim
20 words
A process according to claim 1 wherein said second temperature is in the range of 465° F to 485° F.
Claim 8
Dependent Claim
24 words
A process according to claim 1 wherein said article is held at said second temperature for a period of 115 minutes to 125 minutes.
Claim 9
Dependent Claim
26 words
A process according to claim 1 wherein quenching of said article to said second temperature is carried out by soaking said alloy in a salt bath.
Claim 10
Dependent Claim
21 words
A process according to claim 8 wherein said salt bath comprises a mixture of sodium nitrite, sodium nitrate and potassium nitrate.
Claim 11
Dependent Claim
24 words
A process according to claim 1 wherein quenching of said article to said second temperature is carried out by means of an oil bath.
Claim 12
Dependent Claim
24 words
A process according to claim 1 wherein quenching of said article to said second temperature is carried out by means of a fluidized bed.
Claim 13
Dependent Claim
49 words
A process according to claim 1 wherein said cooling is carried out by exposing said article to ambient air until the temperature of said article reaches approximately 180° F, and further cooling said article to ambient temperature by further exposing said article to ambient air after a water rinse.
Claim 14
Dependent Claim
17 words
A process according to claim 1 wherein said cooling is carried out by means of forced air.
Claim 15
Dependent Claim
18 words
A process according to claim 1 wherein said cooling is carried out by means of a water rinse.
Claim 16
Dependent Claim
18 words
A process according to claim 1 wherein said cooling is carried out by means of an oil bath.
Claim 17
Dependent Claim
13 words
A process according to claim 1 wherein said article is a machine element.
Claim 18
Dependent Claim
21 words
A process according to claim 1 wherein said selected portions are heated to said first temperature by a localized heating source.
Claim 19
Dependent Claim
18 words
A process according to claim 1 wherein said carbon is present in the range of 3.50% to 3.80%.
Claim 20
Dependent Claim
18 words
A process according to claim 1 wherein said silicon is present in the range of 2.10% and 2.40%.
Claim 21
Dependent Claim
18 words
A process according to claim 1 wherein said manganese is present in the range of 0.00% and 0.30%.
Claim 22
Dependent Claim
18 words
A process according to claim 1 wherein said molybdenum is present in the range of 0.20% and 0.60%.
Claim 23
Dependent Claim
18 words
A process according to claim 1 wherein said phosphorus is present in the range of 0.00% and 0.05%.
Claim 24
Dependent Claim
18 words
A process according to claim 1 wherein said copper is present in the range of 0.80% and 1.20%.
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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) | 1992-11-13 | 1993-05-15 | 1993-11-14 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1996-11-13 | 1997-05-15 | 1997-11-14 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2000-11-13 | 2001-05-15 | 2001-11-14 | $7700.00 | Window Closed / Lapsed |