JPS63302102A - Manufacture of turbine blade - Google Patents

Abstract

PURPOSE:To strengthen the installation of a corrosion preventive leaf by fixing the corrosion preventive leaf on the junction leaf which is made of a titanium alloy while copying the form of a blade leading edge, by means of diffused junction in such a way that the back of a junction leaf base is welded by means of fusion onto the leading edge of a turbine blade made of a titanium alloy. CONSTITUTION:By the use of high pressure isotropic pressing process, a corrosion preventive leaf 11 made of, for instance, a Co base alloy consisting of Co-3%Cr-4%W-1.2%C is fixed by means of diffused junction onto a junction leaf 12 which is made of a titanium alloy so as to be extended to an appropriate length while copying the form of a leading edge, and is combined with bent-up sections 12b rising up from a base section 12a at both ends thereof. Then, the base 12a of the aforesaid junction leaf 12 is monolithically fixed on a turbine blade 13 consisting of, for instance, Ti-6%Al-4%V by means of electron beam welding. In this case, care should be taken so as to maintain a gap greater than at least, 2mm between a welded section 14 and the junction of the corrosion preventive leaf 11, thereby preventing the junction thereof from being melted by the thermal effect of electron beam welding.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Field of Industrial Application) The present invention relates to a method for manufacturing a turbine blade made of a titanium alloy.

(Prior Art) It is known that the leading edge of the blade in the final stage of a steam turbine is eroded due to collision of condensate (water droplets) in the steam, changing the blade shape and reducing turbine performance. ing. Therefore, in conventional turbine blades made of ferritic stainless steel such as 12Ct41, corrosion prevention pieces made of CO-based alloy are attached by melt welding or brazing to locally enhance the corrosion prevention function. .

FIG. 6 shows a typical case where the leading edge of a wing is protected by such an erosion prevention piece. The leading edge of the blade 1 is shaved off to an appropriate length, the back surface of the erosion prevention piece 2 is brought into contact with this, and the two are integrated by fusion welding. In addition, the code|symbol 3 has shown the welding part.

(Problem to be solved by the invention) In recent years, there has been active research into using titanium alloys, which are lightweight and have high specific strength, as turbine blades with the aim of improving the performance of steam turbines, and practical application is imminent. It is becoming. Although titanium alloys have excellent corrosion resistance, they have a property that they are inferior to erosion accompanied by impact.

On the other hand, titanium alloys tend to form brittle intermetallic compounds, making fusion welding with Co-based alloys difficult. For this reason, β-type titanium alloys, which can be melt-welded with titanium alloys and have high hardness, are used as corrosion prevention pieces. However, the corrosion resistance of this β-type titanium alloy is
It is about 1/3 compared to O-based alloys, which is not sufficient as an erosion prevention piece.

In addition, as a method of imparting a high anticorrosion function to titanium alloys, there is a method of irradiating metal carbides and metal nitrides with excellent corrosion resistance with a high-energy beam and fusing them together. However, since these materials are highly hard materials, if the film thickness is increased, cracks will occur due to residual stress during melting, making it impossible to increase the film thickness. There is a concern that damage may occur in the blade base material, resulting in a decrease in efficiency.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a method for manufacturing a turbine blade, which solves the problems of the prior art as described above and allows a material with excellent corrosion resistance to be integrally bonded to a titanium alloy blade base material. It is in.

[Structure of the invention]

(Means for Solving the Problems) A method for manufacturing a turbine blade according to the present invention uses a titanium alloy material, is extended to an appropriate length following the leading edge of the blade, and has bent portions rising from the base at both ends. Next, diffusion bonding is performed on the erosion prevention piece, which is formed so that the base and inner edge, the bent part and both side edges are in contact with each other, and the outer edge is opened outward. The erosion prevention piece and the turbine blade are integrally joined by melt welding the back surface of the base of the joint piece to the front rut of the titanium alloy turbine blade.

(Function) According to the present invention, an erosion prevention piece manufactured using a highly erodible material such as a Co-based alloy, a metal carbide, or a metal nitride is diffused in the same phase into a joining piece made of a titanium alloy. Since it is bonded and then integrated into the turbine blade as an erosion prevention piece, the processing temperature during diffusion bonding can be performed without being affected by the transformation temperature of the titanium alloy.
Since the erosion prevention piece and the titanium alloy can be easily joined together and the joining temperature can be kept high, it is possible to improve the adhesion.

Furthermore, since the processing temperature can be increased, it is possible to provide the above-mentioned high melting point material with excellent corrosion resistance.

Furthermore, since the erosion prevention piece is not directly bonded to the blade base material, there is no adverse thermal effect on the embedded part, which is a strength component of the turbine blade. In addition, since the size of the erosion prevention piece is relatively small during cross-bonding, pressure control is easy and temperature distribution can be maintained uniformly. . It has the advantage that diffusion bonding can also be performed.

When attaching this erosion prevention piece to the blade base material, the joining pieces are made of titanium alloy, so titanium alloys must be welded together.
Commonly used fusion welding, such as electron beam welding, can be applied. At this time, even if the joint pieces are altered due to heating during dissipative welding, it is possible to restore only the erosion prevention pieces by heat treatment before welding, which causes problems in weldability with the blade base material. Never.

(First Example) Figure 1 shows Co-30%Cr-4%V-1,2%C Co
The corrosion prevention piece 11 formed of the base alloy is Ti-6%A.
The figure shows a bonded piece 12 made of Q-4%V titanium alloy, which is diffusion-bonded using high-temperature isostatic pressure treatment. Note that the reference numeral 12a indicates a base and the reference numeral 12b indicates a bent portion. The processing temperature during this diffusion bonding was 900° C., the holding time was 2.5 hours, and the applied pressure was 100 MPa (pressure using argon gas). The tensile strength of the diffusion bonded portion is sufficiently higher than that of a 12Cr turbine blade in which a Co-based alloy is attached by brazing.

In FIG. 2, the base 12a of this joint piece 12 is made of Ti-6%A.
It is shown fixed to and integrated with a turbine blade 13 made of Q-4%V by electron beam welding.

In this case, care is taken to maintain a distance of at least 2 m or more between the welded part and the joined part of the erosion prevention +h piece 11, so that the joined part does not melt due to the thermal influence of electron beam welding. In addition, the code|symbol I4 has shown the welding part.

Note that FIG. 3 shows the entire turbine blade 13 to which the erosion prevention piece 11 is integrally connected.

(Second Example) In FIG. 4, a TiC powder material 15 is used as an anticorrosive material, placed on a joint piece 16 made of Ti-6%AQ-4%V, and wrapped in a container 17 made of carbon steel. This figure shows the structure of an erosion prevention piece 18 that is sintered using high-temperature isostatic pressure treatment and diffusion bonded as in the previous embodiment.

That is, the erosion prevention piece 18, which has been sintered and integrated with the joint piece 16 inside the container 17, is then taken out by scraping the container 17, and is finished into a shape that follows the leading edge of the blade, as shown in FIG. As shown in the figure, it is melted by electron beam welding and integrated with the turbine blade I3. In addition, the code|symbol 19 has shown the welding part.

〔Effect of the invention〕

As explained above, the present invention uses a titanium alloy material to form a joint piece that is extended to an appropriate length following the leading edge of the blade and has bent portions rising from the base at both ends, and then this joint piece is On the other hand, an erosion prevention piece formed such that the base and the inner edge are in contact with each other, the bent side and both side edges are in contact with each other, and the outer edge is opened outward is fixed by diffusion bonding,
Furthermore, the back surface of the base of the joining piece is melt-welded to the leading edge of the titanium alloy turbine blade to integrally connect the erosion prevention piece and the turbine blade. It can be attached to a titanium alloy turbine blade while maintaining the desired attachment strength.

Therefore, according to the present invention, an excellent effect is achieved in that erosion accidents at the leading edge of a turbine blade made of a titanium alloy are prevented.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing one embodiment of the erosion prevention piece according to the present invention, and FIG. 2 is a perspective view showing a state in which the erosion prevention piece according to the invention is coupled to the leading edge of a turbine blade. FIG. 3 is a configuration diagram showing the entire turbine blade, FIGS. 4 and 5 are perspective views showing other embodiments, and FIG. 6 is an example of a turbine blade equipped with a conventional erosion prevention piece on the leading edge. FIG. 11, 18...Erosion prevention pieces 12, 16...Joining pieces 13...Turbine blades 15...Powder material 17...Container agent Patent attorney Noriyuki Chika Yudo Ken Daishimaru/'26 Figure 1 Figure 2 Figure 3 Figure 4 Figure 5

Claims (1)

[Claims] A titanium alloy material is used to form a joint piece that is extended to an appropriate length following the leading edge of the wing and has bent portions rising from the base at both ends, and then the base and inner edge of the joint piece are formed. Further, an erosion prevention piece formed such that the bent portion and both side edges are in contact with each other and the outer edge is opened outward is fixed by diffusion bonding, and the back surface of the base of the bonded piece is attached to a titanium alloy turbine blade. A method for manufacturing a turbine blade, characterized in that the erosion prevention piece and the turbine blade are integrally joined by melt welding to the leading edge of the blade.