Appeal 2007-0873
Application 10/395,236
I. BACKGROUND
The invention relates to a heat resistant cast steel. Claim 7 is
illustrative of the subject matter on appeal:
7. A heat resistant cast steel having good thermal fatigue resistance,
consisting essentially of, in weight percent, C: 0.2-0.42%, Ni: 8.0-45.0%,
Cr: 15.0-30.0%, W: up to 10% and Nb: 0.5-3.0%, provided that [%C]-
0.13[%Nb] is in the range of 0.05-0.95%, and the balance being Fe and
inevitable impurities, contents of carbides in the steel being, in atomic
percent, MC carbides 0.5-3.0% and M23M6 carbides 0.5-10%, the matrix
consisting essentially of an austenitic phase mainly comprised of Fe-Ni-Cr,
mean coefficient of thermal expansion in the range from room temperature
to 1050°C being up to 20.0x10-4, and tensile strength in the temperature
range up to 1050°C being 50 MPa or higher.
The Examiner relies on the following prior art references to show
unpatentability:
Yabuki (as translated)1 JP58-217663 Dec. 17, 1983
Key to steel, Verlag Stahlschlussel (10th ed., West Germany 1974)
The rejections as presented by the Examiner are as follows:
1. Claims 7, 8, 10, and 11 are rejected under 35 U.S.C. § 103(a) as
unpatentable over Yabuki; and
2. Claim 9 is rejected under 35 U.S.C. § 103(a) as unpatentable over
Yabuki in view of the Key to Steel.
1 We cite to the full translation provided by the Examiner.
2
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