Appeal No. 2006-2781
Application 10/254,671
INTRODUCTION
The invention is directed to a heat-resisting steel which can be used in
a high-temperature steam environment, for example, in a steam turbine in a
power station. Claims 1, 5, 7, and 8 are illustrative:
1. A Nb-free heat-resisting 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.
5. A heat-resisting 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.
7. A Nb-free heat-resisting steel having precipitates of M7C3, MX and
M23C6, which are precipitated within the crystal grains or at the crystal grain
boundaries as a result of a hot forging treatment, an annealing treatment, a
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, 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 sum
of said precipitates falling within a range of 0.5% to 2.0% by mass.
8. A heat-resisting steel having precipitates of M1,C3, MX and M23C6,
which are precipitated within the crystal grains or at the crystal grain
boundaries as a result of a hot forging treatment, an annealing treatment, a
2
Page: Previous 1 2 3 4 5 6 7 8 9 10 Next
Last modified: November 3, 2007