Appeal No. 2006-2781
Application 10/254,671
normalizing treatment, a quenching treatment and a tempering treatment
applied in the order mentioned to a steel comprising 0.25 to 0.35% by mass
of C, not more than 0.15% by mass of Si, 0.2 to 0.8% by mass of Mn, 0.3 to
0.6% by mass of Ni, 1.6 to 1.9% by mass of Cr, 0.23 to 0.30% by mass of V,
0.6 to 1 .l% by mass of Mo, 0.6 to 1.4% by mass of W, 0.001 to 0.008% by
mass of Nb, 1.3 to 1.4% by mass of Mo + W/2, and the balance of Fe and
unavoidable impurities, the sum of said precipitates falling within a range of
0.5% to 2.0% by mass.
11. A method of manufacturing a Nb-free heat-resisting steel,
comprising applying a quenching treatment to a steel comprising 0.25 to
0.35% by mass of C, not more than 0.15% by mass of Si, 0.2 to 0.8% by
mass of Mn, 0.3 to 0.6% by mass of Ni, 1.6 to 1.9% by mass of Cr, greater
than 0.30 but less than or equal to 0.35% by mass of V, 0.6 to 1.1% by mass
of Mo, 0.6 to 1.4% by mass of W, 1.3 to 1.4% by mass of Mo + W/2, at least
one of N and B, the N being 0.002 to 0.008% by mass and the B being 0.001
to 0.004% by mass, and the balance of Fe and unavoidable impurities, the
initiating temperature of said quenching treatment falling within a range of
970°C to 1,020°C.
15. A method of manufacturing a heat-resisting steel, comprising
applying a quenching treatment to a steel comprising 0.25 to 0.35% by mass
of C, not more than 0.15% by mass of Si, 0.2 to 0.8% by mass of Mn, 0.3 to
0.6% by mass of Ni, 1.6 to 1.9% by mass of Cr, 0.23 to 0.30% by mass of V,
0.6 to 1.1% by mass of Mo, 0.6 to 1.4% by mass of W, 0.001 to 0.008% by
mass of Nb, 1.3 to 1.4% by mass of Mo + W/2, and the balance of Fe and
unavoidable impurities, the initiating temperature of said quenching
treatment falling within a range of 1,020°C to 1,050°C.
The Examiner relies on the following prior art references to show
unpatentability:
Kawano US 6,514,359 B2 Feb. 4, 2003
Fujita US 6,569,269 B1 May 27, 2003
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