WO2023184837A1

WO2023184837A1 - Method for preventing single crystal hollow guide vane from being recrystallized

Info

Publication number: WO2023184837A1
Application number: PCT/CN2022/114643
Authority: WO
Inventors: 贾玉亮; 杜应流; 蔡俊成; 张吉星; 汪兴芳; 张丽
Original assignee: 安徽应流航源动力科技有限公司
Priority date: 2022-03-28
Filing date: 2022-08-25
Publication date: 2023-10-05
Also published as: CN114850397B; CN114850397A; DE112022002432T5

Abstract

A method for preventing a single crystal hollow guide vane from being recrystallized. The method comprises optimizing a vertical sharp-angle structure at an outlet of an inner cavity of the single crystal hollow guide vane into a round-angle structure to form a cambered surface (1c) and modifying a profiling mold; bending a mold core (2) along the cambered surface of the hollow guide vane to form a shoulder (2a), which is attached to the cambered surface and surrounds a longitudinal section of the mold core to form an annular structure; putting the mold core into the modified profiling mold, and injecting wax by means of a wax injection machine to obtain a hollow guide vane wax mold (1); and obtaining a blank after housing making, dewaxing, pouring, and housing removal. The method effectively prevents the sharp-angle structure of the single crystal hollow guide vane from being recrystallized by means of optimizing the structure at an outlet of an inner cavity of a wax mold and a mold core structure to form the round-angle structure, avoids stress concentration after solidification, ensures the quality of a single crystal hollow guide vane casting, and increases the qualification rate of the single crystal hollow guide vane.

Description

A method to prevent recrystallization of single crystal hollow guide blades

Technical field

The present invention relates to the technical field of investment casting, and in particular to a method for preventing recrystallization of single crystal hollow guide vanes.

Background technique

High-temperature alloy turbine single-crystal blades are known as the crown jewel of industrial technology. Recrystallization control technology is one of the key technologies in the development of single-crystal blades. At present, the control of recrystallization of hollow blades at home and abroad is mostly focused on electrolytic corrosion and carburization. , sputtering and other physical and chemical methods, U.S. Patent US2014/022990 preliminarily discusses the impact of casting fillets on recrystallization, and analyzes the causes of recrystallization at the casting corners. When the casting fillets are smaller, the alloy solidifies to produce more concentrated residues. Stress will induce recrystallization during heat treatment; when the casting fillet is enlarged, the stress during solidification of the alloy is relatively dispersed and the residual stress is small, making it difficult to induce recrystallization during heat treatment. It is only explained that the rounded corner structure can reduce the risk of recrystallization. The theory is elaborated, but no specific implementation plan is proposed, and how to implement it on castings.

Recrystallization of single-crystal blades is caused by casting stress-driven effects and is formed during subsequent high-temperature heat treatment. The exit of the inner cavity of the traditional single crystal hollow guide vane has a sharp angle structure, as shown in Figures 1 and 2. The exit of the inner cavity of the single crystal hollow guide vane wax model 1, the surface of the wax model at the exit of the inner cavity is the end surface 1a of the wax model, and the inner cavity The inner wall surface 1b is coplanar with the surface of the core 2, and the wax pattern end surface 1a is perpendicular to the adjacent inner cavity inner wall surface 1b; see Figure 2, the sharp corner structure of this part forms stress concentration during casting. After heat treatment, in the single crystal casting 4 Recrystallization areas 5 will be formed at the sharp corners, causing defects in the hollow guide blades and affecting performance. In addition, the length t1 of the positioning section of the core 2 extending into the mold shell 3 is 10mm to 20mm, resulting in an increase in the thickness of the mold shell. , affecting the solidification heat dissipation efficiency and stability.

Contents of the invention

The main purpose of the present invention is to provide a method for preventing the recrystallization of single-crystal hollow guide blades. By optimizing the structure of the exit of the inner cavity of the wax mold and the matching structure of the core and the exit of the inner cavity of the wax mold, it is designed into a round shape. The corner structure effectively prevents recrystallization at the sharp corner structure of single crystal hollow guide blades, avoids stress concentration after solidification, ensures the quality of single crystal hollow guide blade castings, improves the qualification rate of single crystal hollow guide blades, and can effectively Solve problems in background technology.

In order to achieve the above object, the technical solution adopted by the present invention is: a method for preventing recrystallization of single crystal hollow guide blades, which includes the following steps:

1) Optimize the structure of the wax pattern of the single crystal hollow guide vane, which is located at the exit of the inner cavity of the single crystal hollow guide vane wax pattern, and optimize the vertical sharp corner structure at the exit of the inner cavity of the single crystal hollow guide vane. A rounded corner structure is formed to form an arc surface, and the pressing mold is modified according to the structure at the exit of the inner cavity of the optimized blade wax model;

2) Optimize the core structure, bend the core along the arc surface of the hollow guide blade to form a convex shoulder, the convex shoulder fits the arc surface, and the convex shoulder surrounds the longitudinal section of the core to form an annular structure;

3) Put the optimized core into the modified pressing mold in step 1), and inject wax through a wax injection machine to obtain a hollow guide blade wax pattern;

4) Mold the hollow guide vane wax shell in step 3), and after drying and hardening, obtain the hollow guide vane shell;

5) After dewaxing, pouring and shelling the hollow guide blade shell, a single crystal hollow guide blade blank is obtained, and the blank is processed to obtain a single crystal hollow guide blade casting.

The structure at the exit of the wax pattern cavity optimized in step 1 is the end surface of the wax pattern. The inner wall surface of the wax pattern interior cavity is coplanar with the surface of the core. The end surface of the wax pattern is perpendicular to the inner wall surface of the adjacent wax pattern interior cavity.

The arc radius R of the arc surface in step 1 is 0.4-1.2mm.

In step 2, the height of the shoulder is the same as the height of the end wall of the wax pattern, both are t3.

In step 2, the length t2 of the shoulder is 2-10mm, making the length of t2 smaller than the length of t1, reducing the length of the positioning section of the core into the mold shell, reducing the thickness of the mold shell, and improving the solidification and heat dissipation efficiency and stability of the molten metal. .

In step 4, the hollow guide blade mold shell includes a wax mold, a core and a mold shell. The end face of the core close to the mold shell has an inward concave arc surface structure, which matches the corresponding mold shell's outward protruding arc surface structure.

Compared with traditional technology, the beneficial effects produced by the present invention are: the present invention optimizes the structure of the exit of the inner cavity of the wax model and the matching structure of the core and the exit of the inner cavity of the wax model, and designs it into a rounded structure, which is effective It effectively prevents recrystallization at the sharp corner structure of the single crystal hollow guide blade, avoids stress concentration after solidification, ensures the quality of the single crystal hollow guide blade casting, and improves the qualification rate of the single crystal hollow guide blade.

Description of drawings

Figure 1 is a schematic structural diagram of the exit of the inner cavity of a traditional single crystal hollow guide blade;

Figure 2 is a schematic diagram of recrystallization formed at the exit of the inner cavity of a traditional single crystal hollow guide blade;

Figure 3 is a schematic diagram of the structural optimization of the inner cavity outlet of the single crystal hollow guide blade of the present invention.

In the picture: 1. Wax mold; 1a, end face of the wax mold; 1b, inner wall surface of the wax mold cavity; 1c, arc surface; 2. core; 2a, shoulder; 3. mold shell; 4. single crystal casting; 5. Recrystallization area.

Detailed ways

In order to make the technical means, creative features, objectives and effects achieved by the present invention easy to understand, the present invention will be further elaborated below in conjunction with specific implementation modes.

As shown in Figure 3, a method to prevent recrystallization of single crystal hollow guide vanes includes the following steps:

1) Optimize the structural part of the single crystal hollow guide vane wax pattern. This part is located at the exit of the inner cavity of the single crystal hollow guide vane wax pattern 1. The optimized structure at the exit of the inner chamber of the wax pattern 1 is the wax pattern end face 1a. The inner wall surface 1b of the mold cavity is coplanar with the surface of the core, and the end surface 1a of the wax mold is perpendicular to the inner wall surface 1b of the adjacent wax mold cavity. In this position, the single crystal hollow guide blade has a vertical sharp angle structure at the exit of the inner cavity, that is, The vertical intersection of 1a and 1b is optimized into a rounded structure, forming an arc surface 1c on the surface of the wax model. The arc radius R of the arc surface 1c is 0.4-1.2mm, and according to the optimized outlet of the inner cavity of the blade wax model The structural modification of the pressing mold;

2) To optimize the core structure, bend the core 2 along the arc surface 1c of the hollow guide blade to form a convex shoulder 2a. The convex shoulder 2a fits the arc surface 1c, and the convex shoulder 2a surrounds the longitudinal section of the core 2. Forming a ring structure, the height of the shoulder 2a is the same as the height of the side wall of the wax mold end face 1a, both are t3. The length t2 of the shoulder 2a is 2-10mm. The length of t2 is less than the length of t1, which reduces the insertion of the core 2 into the mold shell. The length of the positioning section 3 reduces the thickness of the mold shell 3 and improves the solidification and heat dissipation efficiency and stability of the molten metal.

4) Mold the hollow guide blade wax shell in step 3). After drying and hardening, a hollow guide blade shell is obtained. The hollow guide blade shell includes a wax mold 1, a core 2 and a shell 3. The core 2 is close to The end surface of the mold shell 3 has an inward concave arc surface structure, and the corresponding mold shell 3 has an outward protruding arc surface structure, which can reduce the thickness of the mold shell to a certain extent and improve the heat dissipation effect.

The working principle of the invention is: by modifying and matching the core and the wax mold, the core convex shoulder at the outlet of the inner cavity of the single crystal hollow guide blade is formed, and the sharp corner structure at the outlet of the inner cavity of the single crystal hollow guide blade is optimized into a round shape. The angular structure reduces the casting stress concentration during solidification, thereby preventing the occurrence of recrystallization and avoiding the casting stress concentration during solidification.

Certain exemplary embodiments of the present invention have been described above only by way of illustration. It goes without saying that those skilled in the art can implement various embodiments in various ways without departing from the spirit and scope of the present invention. The described embodiments are modified. Therefore, the above drawings and descriptions are illustrative in nature and should not be construed as limiting the scope of the claims of the present invention.

Claims

A method for preventing recrystallization of single crystal hollow guide blades, which is characterized by: including the following steps:

1) Optimize the structure of the wax pattern of the single crystal hollow guide vane, which is located at the exit of the inner cavity of the single crystal hollow guide vane wax pattern, and optimize the vertical sharp corner structure at the exit of the inner cavity of the single crystal hollow guide vane. A rounded corner structure is formed to form an arc surface, and the pressing mold is modified according to the structure at the exit of the inner cavity of the optimized blade wax model;

2) Optimize the core structure, bend the core along the arc surface of the hollow guide blade to form a convex shoulder, the convex shoulder fits the arc surface, and the convex shoulder surrounds the longitudinal section of the core to form an annular structure;

3) Put the optimized core into the modified pressing mold in step 1), and inject wax through a wax injection machine to obtain a hollow guide blade wax pattern;

4) Mold the hollow guide vane wax shell in step 3), and after drying and hardening, obtain the hollow guide vane shell;

5) After dewaxing, pouring and shelling the hollow guide blade shell, a single crystal hollow guide blade blank is obtained, and the blank is processed to obtain a single crystal hollow guide blade casting.
A method for preventing recrystallization of single crystal hollow guide blades according to claim 1, characterized in that: the structure at the exit of the wax mold cavity optimized in step 1 is the end face of the wax mold, and the inner wall surface of the wax mold cavity is in line with the shape of the wax mold. The core surfaces are coplanar, and the end surface of the wax pattern is perpendicular to the inner wall surface of the adjacent wax pattern cavity.
A method for preventing recrystallization of single crystal hollow guide blades according to claim 1, characterized in that: in step 1, the arc radius R of the arc surface is 0.4-1.2 mm.
A method for preventing recrystallization of single crystal hollow guide blades according to claim 1, characterized in that in step 2, the height of the shoulder is the same as the height of the end face side wall of the wax mold, both of which are t3.
A method for preventing recrystallization of single crystal hollow guide blades according to claim 1, characterized in that in step 2, the length t2 of the shoulder is 2-10 mm.
A method for preventing recrystallization of single crystal hollow guide blades according to claim 1, characterized in that: in step 4, the hollow guide blade mold shell includes a wax mold, a core and a mold shell, and the end of the core close to the mold shell faces There is a concave arc structure on the inside, and the corresponding shell has a convex arc structure on the outside.