Metal treatment – Stock – Ferrous
Reexamination Certificate
2006-12-26
2006-12-26
Wilkins, III, Harry D (Department: 1742)
Metal treatment
Stock
Ferrous
C420S044000
Reexamination Certificate
active
07153373
ABSTRACT:
A CF8C type stainless steel alloy and articles formed therefrom containing about 18.0 weight percent to about 22.0 weight percent chromium and 11.0 weight percent to about 14.0 weight percent nickel; from about 0.05 weight percent to about 0.15 weight percent carbon; from about 2.0 weight percent to about 10.0 weight percent manganese; and from about 0.3 weight percent to about 1.5 weight percent niobium. The present alloys further include less than 0.15 weight percent sulfur which provides high temperature strength both in the matrix and at the grain boundaries without reducing ductility due to cracking along boundaries with continuous or nearly-continuous carbides. The disclosed alloys also have increased nitrogen solubility thereby enhancing strength at all temperatures because nitride precipitates or nitrogen porosity during casting are not observed. The solubility of nitrogen is dramatically enhanced by the presence of manganese, which also retains or improves the solubility of carbon thereby providing additional solid solution strengthening due to the presence of manganese and nitrogen, and combined carbon.
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Maziasz Philip J.
McGreevy Tim
Pollard Michael James
Siebenaler Chad W.
Swindeman Robert W.
Caterpillar Inc
Finnegan, Henderson, Farabow, Garrett&Dunner
Wilkins, III Harry D
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