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US 4,880,477 AGranted
Process of making an austempered ductile iron article
AssigneeTextron Inc.
InventorsWilliam J. Hayes, Harry A. Matrone, Philip D. Johnson
Life of this patent
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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.
Claims23
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.degree. F and 2100.degree. F for a period of one second to 100 seconds;
- quenching the article to a second temperature of 450.degree. F to 850.degree. 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.
5 more elements
Dependencies are inferred from the claim text.