Appeal 2007-2207
Application 10/181,810
3. A high-strength dual-phase cold rolled steel sheet having an
excellent deep drawability, characterized in that the steel sheet has a
composition comprising:
C: 0.01-0.032 mass%, Si: 0.01-1.0 mass%, Mn: about
1.43-2.02 mass%, P: 0.001-0.10 mass%, S: 0.0001-0.02 mass%,
Al: 0.005-0.20 mass%, N: 0.0001-0.12 mass% and V: 0.01-0.5 mass%
and further comprising not more than 0.3 mass% in total of one or two of
Nb: more than 0 mass% but not more than 0.3 mass% and Ti: more than
0 mass% but not more than 0.3 mass%,
provided that V, Nb, Ti and C satisfy a relationship of
0.55xC/12 ≤ (V/51+2xNb/93+2xTi/48) ≤ 3xC/12, and the remainder being
Fe and inevitable impurities, and has a microstructure consisting of a ferrite
phase as a primary phase and a secondary phase including martensite phase
at an area ratio of not less than 1% to a whole of the microstructure,
wherein the steel sheet has a tensile strength of not less than 450 MPa
and not more than 630 MPa and has an R-value of not less than 1.4.
The Examiner relies upon the following references as evidence of
obviousness:
Matsuo (as translated) JP 55-158226 Dec. 9, 1980
Hashiguchi (as translated) JP 57-067131 A Apr. 23, 1982
Suzuki 6,410,163 B1 June 25, 2002
Appellants' claimed invention is directed to dual-phase cold rolled
steel wherein the primary phase is ferrite and the secondary phase of the
steel is martensite.
Appealed claims 3, 5, 13, 14, 27 and 28 stand rejected under
35 U.S.C. § 103(a) as being unpatentable over JP '226 in view of JP '131
and Suzuki.
We have thoroughly reviewed each of Appellants' arguments for
patentability. However, we are in full agreement with the Examiner that
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