Rotary kinetic fluid motors or pumps – Working fluid passage or distributing means associated with... – Specific casing or vane material
Reexamination Certificate
1999-08-05
2001-03-27
Look, Edward K. (Department: 3745)
Rotary kinetic fluid motors or pumps
Working fluid passage or distributing means associated with...
Specific casing or vane material
C416S24100B
Reexamination Certificate
active
06206634
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a steam turbine blade made of Ti-base alloy, a method of manufacturing the same, a steam turbine power generating plant using the same and a low pressure steam turbine.
2. Description of the Related Art
Conventionally, in a low pressure final stage of a steam turbine, there have been developed 12Cr steel for a blade having 33.5 inch length, Ti-6Al-4V for a blade having 40 inch length, and high strength 12Cr steel for a blade having 43 inch length which is the longest in the world as a machine corresponding to 50 Hz, however, a demand for improving an efficiency and compactifying the plant in accordance that the final blade stage is made long is increased more and more, so that it is required to further lengthen the blade. In order to achieve the requirement, a titanium alloy having a light weight and a high strength is indispensable in place of Ti-6Al-4V which has been practically used.
A titanium alloy in class of tensile strength 95 kg/mm
2
can sufficiently correspond to an increase of a centrifugal force caused by the blade having the increased length till the blade having 40 inch, however, in the blade having a length equal to or more than 45 inch, a titanium alloy in class of tensile strength 110 kg/mm
2
is required. As the titanium alloy having a tensile strength equal to or more than 110 kg/mm
2
, there is a &bgr; type titanium alloy having an age hardening property, however, since the &bgr; type titanium alloy has a disadvantage, that is, a toughness is low, there is a problem in manufacturing a whole of the blade by this alloy. On the contrary, in an &agr;+&bgr; type titanium alloy having a high toughness, a cooling speed for a solid solution treatment largely affects the strength in accordance that a dovetail of the blade becomes thick, so that the strength which can be obtained in a small steel lump can not be frequently realized in a large-sized product. Accordingly, it has been hard to securely obtain a titanium alloy in class of 110 kg/mm
2
.
Further, in Japanese Patent Unexamined Publication No. 1-202389, there is described that a solid solution treatment is executed at a temperature equal to or less than 10 to 60° C. corresponding to a point of &bgr; transformation with respect to a condition for a heat treatment of Ti-6Al-6V-2Sn corresponding to an &agr;+&bgr; type high strength Ti alloy, that is, at 867 to 917° C. and an age treatment is thereafter executed at 500 to 650° C., however, in accordance with this treatment, there has been a problem that the strength can be obtained in a thin blade profile portion, but the strength can not be secured in a thick dovetail portion in which a cooling speed is low.
Further, in Japanese Patent Unexamined Publication No. 7-150316, there is described a turbine blade made of Ti-base alloy containing 3 to 5% of Al, 2.1 to 3.7% of V, 0.85 to 3.15% of Mo and 0.85 to 3.15% of Fe as a material for the turbine blade, however, there is not indicated an age treatment.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a steam turbine blade made of Ti-base alloy comprising an &agr;+&bgr; type phase in which a difference of a tensile strength is small between a blade portion and a dovetail portion, a tensile strength at a room temperature of the dovetail portion is equal to or more than 100 kg/mm
2
and a suitable toughness is commonly provided together with a strength, as a steam turbine blade having a length of 43 inch or more, a method of manufacturing the same, a steam turbine power generating plant and a low pressure steam turbine.
In accordance with the present invention, there is provided a steam turbine blade having a blade portion and a plurality of fork type or inverted Christmas tree type dovetails, wherein the blade is made of Ti-base alloy structured such that a length of the blade portion is equal to or more than 52 inches with respect to a rotational speed 3000 rpm of the blade or equal to or more than 43 inches with respect to the rotational speed 3600 rpm, and a tensile strength at a room temperature of the dovetail is equal to or more than 100 kg/mm
2
, preferably equal to or more than 110 kg/mm
2
and equal to or more than 96% of the tensile strength at the room temperature of the blade portion.
In accordance with the present invention, there is provided a steam turbine blade, wherein the steam turbine blade is made of Ti-base alloy containing Al 4 to 8 weight %, V 4 to 8 weight % and Sn 1 to 4 weight %, a tensile strength of the dovetail at a room temperature is equal to or more than 100 kg/mm
2
, preferably equal to or more than 110 kg/mm
2
, a V notch impact value (y) at a room temperature is equal to or more than a value (kg-m) calculated by a formula (−0.0213x+4.025), or the blade portion is structured such that a tensile strength (x) thereof at a room temperature is equal to or more than 105 kg/mm
2
, the V notch impact value (y) at a room temperature is equal to or more than a value (kg-m) calculated by a formula (−0.0196x+3.93) and the tensile strength of the dovetail at a room temperature is equal to or more than 96% of the tensile strength of the blade portion at a room temperature.
In accordance with the present invention, there is provided a steam turbine blade, wherein the blade is made of Ti-base alloy structured such that a length of the blade portion is equal to or more than 52 inches with respect to a rotational speed 3000 rpm of the blade or equal to or more than 43 inches with respect to the rotational speed 3600 rpm and Al 4 to 8 weight %, V 4 to 8 weight % and Sn 1 to 4 weight % are contained, the blade portion is structured such that a tensile strength (x) at a room temperature is equal to or more than 105 kg/mm
2
and a V notch impact value (y) at a room temperature is equal to or more than a value (kg-m) calculated by a formula (−0.0196x+3.93), or the dovetail is structured such that a tensile strength (x) at a room temperature is equal to or more than 100 kg/mm
2
and a V notch impact value (y) at a room temperature is equal to or more than a value (kg-m) calculated by a formula (−0.0213x+4.025).
In accordance with the present invention, there is provided a method of manufacturing a steam turbine blade made of Ti-base alloy, wherein a solid solution treatment and an age treatment is performed so as to cool by water after heating in a range connecting four points shown by reference symbols A (605° C. and 855° C.), B (590° C. and 790° C.), C (410° C. and 790° C.) and D (410° C. and 855° C.) expressed by (an age temperature and a solid solution treatment temperature) shown in
FIG. 1
of this application, wherein the area expressed by (the age temperature and the solid solution treatment temperature) is structured such that a solid solution treatment and an age treatment is performed so as to cool by water after heating in a range connecting four points shown by reference symbols E (525° C. and 855° C.), F (510° C. and 790° C.), G (410° C. and 790° C.) and H (410° C. and 855° C.) shown in
FIG. 2
of this application, wherein the dovetail portion is roughly processed to a state close to a final shape prior to a final heat treatment and next a solid solution treatment and an age treatment is performed so as to cool by water after heating in a range connecting four points shown by reference symbols J (685° C. and 855° C.), K (585° C. and 790° C.), L (410° C. and 790° C.) and M (410° C. and 855° C.) expressed by (an age temperature and a solid solution treatment temperature) shown in
FIG. 3
of this application, and wherein the dovetail portion is roughly processed to a state close to a final shape prior to a final heat treatment and next a solid solution treatment and an age treatment is performed so as to cool by water after heating in a range connecting four points shown by reference symbols N (575° C. and 855° C.), O (560° C. and 790° C.), P (410° C. and 790° C.) and Q (410° C. and 855° C.) expressed by (an age temperature
Doi Hiroyuki
Imano Shinya
Kuriyama Mitsuo
Nakamura Shigeyoshi
Onoda Takeshi
Hitachi , Ltd.
Look Edward K.
Mattingly Stanger & Malur, P.C.
Nguyen Ninh
LandOfFree
Steam turbine blade, method of manufacturing the same, steam... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Steam turbine blade, method of manufacturing the same, steam..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Steam turbine blade, method of manufacturing the same, steam... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2520492