WO2016070779A1

WO2016070779A1 - Electric melting method for forming nuclear power plant voltage regulator cylinder

Info

Publication number: WO2016070779A1
Application number: PCT/CN2015/093637
Authority: WO
Inventors: 王华明
Original assignee: 南方增材科技有限公司
Priority date: 2014-11-04
Filing date: 2015-11-03
Publication date: 2016-05-12
Also published as: CN104532236B; CN104532236A

Abstract

An electric melting method for forming a nuclear power plant voltage regulator cylinder: a high-energy heat source formed by combining electric arc heat, resistance heat, and electroslag heat is employed to melt a continuously conveyed raw material metal wire (1), which is solidified and deposited layer-by-layer on a substrate (2) to form a manufactured metal structure; an electric melting head (6) and a substrate (2) are connected to either electrode of a power source, when forming, the raw material metal wire (1) is fed to a surface of the substrate (2) via a conveyor mechanism (5) and the electric melting head (6), under the protection of a stack of a granular auxiliary material (3), an electric arc (9) is produced between the raw material wire (1) and the substrate (2) to partly melt the surfacing auxiliary material (3) to form a molten slag pool (8), an electric current flows through the raw material wire (1) and the molten auxiliary material slag pool (8) to form resistance heat and electroslag heat, the raw material wire (1) is molten under the effect of the high-energy heat source combining the electric arc heat, the resistance heat, the electroslag heat, a partly molten pool (11) is formed on the surface of the substrate (2), conveyance of the raw material wire (1) and the auxiliary material (3) is continued, a computer is employed to control relative movements of the electric melting head (6) and of the substrate (2) on the basis of layer slicing data of a forming component, rapid cooling and layer-by-layer solidification and deposition of the molten pool on the substrate (2) is implemented, and finally, the voltage regulator cylinder is formed by layer-by-layer deposition.

Description

Nuclear power plant regulator cylinder electrofusion forming method

Technical field

The invention relates to a nuclear power plant voltage regulator cylinder electrofusion forming method.

Background technique

The voltage regulator is one of the core equipment in the primary circuit of the nuclear power plant and is a key component for stabilizing the pressure and temperature of the primary circuit. With the nuclear power working environment and the ultimate safety requirements, the requirements for the preparation process of the voltage regulator equipment are getting higher and higher.

The equipment material adopts ASME standard SA508Gr3Cl2 or RCC-M standard 18MnD5 low alloy high strength steel (China corresponding standard 20MnMoNi). In order to ensure the material quality requirements, the current regulator cylinder components have been changed from the original steel coil welding to forging. And subsequent heat treatment and machining are finally formed. Taking the AP1000 as an example, the main body of the regulator is divided into five material members, wherein the cylindrical member is divided into three parts plus a lower head, and each part is separately manufactured and then integrally welded.

Typical materials are subjected to quenching and tempering heat treatment on a forging basis (usually subjected to one or more normalizing and tempering heat treatments in the middle to diffuse residual hydrogen, refine grains, and prepare for final heat treatment) to obtain strength and toughness. A tempered martensitic material structure with superior overall performance. This method is widely used in production and can also meet the quality requirements. However, for the increasing demand for material component monomers, forging, especially during heat treatment, is prone to problems such as uneven macrostructure. The process is complicated, the chemical and mechanical properties are difficult to control, and the quality stability is poor, and the scrap rate is high. At the same time, from the final grain measurement results of the process, generally only about 5-7 grades, for the purpose of improving the mechanical properties, especially the comprehensive strength and toughness, by further refining the grains as desired in the current research and development production, The process has a big bottleneck.

In addition, the segmented material used in the regulator device is forged and tailor welded. The pattern cuts the continuous direction of the mechanical fiber, greatly affecting the mechanical properties of the material and the safety of the container equipment. And it is also very easy to cause manufacturing delays and increase costs.

Therefore, how to develop the fine grain and uniform structure required by the voltage regulator, and the comprehensive mechanical properties and the overall forming method are the difficult points and important development directions for the development of such new materials.

Summary of the invention

In view of this, the main object of the present invention is to provide a high-efficiency, low-cost, good mechanical performance nuclear power plant regulator body electrofusion forming method.

In order to achieve the above object, the nuclear power plant regulator body electrofusion forming method of the invention is a high-energy heat source which is formed by arc heat, electric resistance heat and electroslag heat, and melts the continuously transported metal raw material wire, on the substrate. Layer solidification stacking to form a metal component;

The electrofusion head and the substrate are connected to the two poles of the power source, and the metal raw material wire is sent to the surface of the substrate through the conveying mechanism and the electrofusion head during the forming, and an arc is generated between the raw material wire and the substrate under the deposition protection of the granular auxiliary material. The molten part of the piled auxiliary material forms a molten slag pool, the electric current flows through the raw material wire material and the molten auxiliary material slag pool to form electric resistance heat and electroslag heat, and the raw material wire is made under the action of three heat composite high energy heat sources of arc heat, electric resistance heat and electroslag heat. The material is melted, a local molten pool is formed on the surface of the substrate, and the raw material wire and the auxiliary material are continuously conveyed. According to the layered slice data of the shaped member, the relative movement of the electrofusion head and the substrate is controlled by a computer to realize the rapid melting of the molten pool on the substrate. The cooling is solidified layer by layer, and finally the voltage regulator cylinder is stacked layer by layer.

In the present invention, the formed regulator cylinder has a diameter of 2-3 meters and a length of 3-12 meters according to the requirements of different nuclear power units.

In the present invention, the raw material wire used for forming is a low-alloy steel material specially prepared for the regulator member, the raw material wire diameter is 2-8 mm, the C content is 0.11-0.15%, and the workpiece C content after forming is 0.05-0.10%, The grain size of the workpiece is 9-10.

In the present invention, the current in the power supply parameter is 200A to 2000A, and the voltage For 20V ~ 50V, the power supply can be DC or AC power. When using DC power, the fuser can be connected to the positive or negative pole.

In the present invention, the preheating and interlaminar temperature of the control substrate or the deposited metal is 120 to 450 ° C, and the relative movement speed of the electrofusion head and the substrate is 300 to 800 mm/min, thereby realizing rapid solidification of the molten pool, thereby obtaining crystals. Fine-grained, non-macro-segregated, uniform-structured materials greatly improve the mechanical properties of the formed workpiece such as plasticity, toughness and high-temperature creep.

In the present invention, in the process of layer-by-layer forming, the raw material filament forms a molten pool on the surface of the lower metal layer, and the molten droplet enters the molten pool in the form of a jet and solidifies to form the two layers of metal into one body, thereby realizing layer forming and integral fusion, thereby ensuring The overall properties of the formed metal component.

In the present invention, the melting efficiency of the single electrofusion head to the raw material wire is 20-50 Kg/h, and in order to achieve rapid formation by increasing the stacking efficiency, the number of the electrofusion heads can be adjusted to 1 to 100 as needed, when multi-electrofusion When the head is arranged, the distance between adjacent electrofusion heads is 50 to 500 mm.

In the present invention, the substrate may be cylindrical or cylindrical and have a wall thickness of not less than 5 mm. The (the axis) is horizontally configured to achieve layer-by-layer stacking by controlling the rotation of the substrate and the relative movement of the electrofusion head in the axial and radial directions of the substrate. The substrate may be 308 stainless steel material or carbon steel or alloy steel material. When it is 308 stainless steel material, it can be used as a dissimilar material to join the composite workpiece. When it is carbon steel or alloy steel material, it can be removed in the subsequent machining.

The invention is free from the constraints of complex tooling, molds and special tools; the forming is a near-net shape blank, and only a small amount of finishing is required after production, which greatly simplifies the processing procedure and shortens the product cycle; the formed workpiece has a similar traditional forging process. The mechanical and chemical properties, strength, toughness, corrosion resistance and other properties are outstanding; at the same time, the integral forming of the regulator cylinder is realized, which breaks through the limitations of the traditional forging process technology, greatly improving the efficiency and saving the cost.

DRAWINGS

1A is a schematic view for explaining an electrofusion forming method in a specific embodiment;

Figure 1B is a partial enlarged view of the vicinity of the position shown in A of Figure 1A;

Fig. 2 is a schematic view for explaining a method of forming a pressure regulator cylinder in the embodiment.

detailed description

Specific embodiments of the present invention will be described below with reference to the accompanying drawings. 1A is a schematic view for explaining an electrofusion forming method in a specific embodiment; and FIG. 1B is a partial enlarged view of a vicinity of a position shown by A in FIG. 1A. Since the figures are schematic, the components in the figures are schematic and their actual shape and size relationships are not limited by the illustration.

In the molding method, the raw material wire 1 is melted and stacked on the base material 2 layer by layer (in the state shown in FIG. 1 when it is deposited on the N-th layer), thereby finally forming a desired metal member.

The specific implementation process is:

A. The wire feeding mechanism 5 feeds the raw material wire 1 to the surface of the substrate 2 placed on the table 21, and is covered with the granular auxiliary material conveyed by the powder feeding mechanism 4.

B. Starting the power supply 12, the power supply voltage causes an arc 9 between the raw material wire 1 and the substrate 2 to generate arc heat, and the arc heat causes part of the auxiliary material 3 to melt, forming an auxiliary slag pool 8, and the current flows through the raw material wire through the electrofusion head 6. 1 Forming resistance heat, and forming electroslag heat through the molten slag pool 8, the three heat sources are combined to form a high-energy heat source, and the raw material wire is melted to form a molten pool 11 on the surface of the substrate 2.

C. Controlling the relative movement of the electrofusion head 6 and the substrate 2 and the temperature of the substrate 2, and realizing the heat exchange and solidification deposition of the molten pool 11 and the substrate.

D. The wire feeding mechanism 5 and the powder feeding mechanism 4 continuously convey the raw material wire 1 and the auxiliary material 3. In the state in which the auxiliary material 3 covers the molten pool 11 and the substrate 2, the raw material wire 1 is deposited on the substrate 2 layer by layer, and finally Form the workpiece.

Wherein, the control device (computer) is based on the shaped workpiece (numerical simulation, Mathematical model) The layered slice data controls the relative movement of the electrofusion head 6 to the substrate 2.

In the illustration of the present invention, the electrode of the electrofusion head is connected positively, and the workpiece is connected to the negative for only a schematic function, or the electrofusion head is connected negatively, the workpiece is connected positively, or an AC power source is taken.

In the present invention, in order to ensure the formation of a good high-energy heat source, especially in order to generate sufficient electroslag heat, the composition of the excipient, the diameter of the raw material wire, the current, the relative movement speed of the substrate and the raw material wire, etc. can be appropriately adjusted. parameter.

In the present invention, the shape of the raw material yarn 1 may be a round bar shape, a belt shape, a solid core or a drug core; the diameter of the raw material wire 1 may be set to 2 to 8 mm according to the size of the formed workpiece; according to the diameter of the wire material 1, The length of the electric fuse head (electrical length) is 20 mm to 150 mm.

In the present invention, the auxiliary material 3 covers a thickness of 15 mm to 120 mm, and the use of the auxiliary material 3 includes: covering the arc 9 to prevent arc splashing; covering the molten pool 11, insulating the air, and protecting the molten pool metal from oxygen, nitrogen and hydrogen in the air. Insulting; forming heat preservation on the molten pool metal; removing impurities and alloying in the metallurgical reaction process; forming the slag pool 8 (slag shell 7) mechanically protecting the deposited metal 10 from forming well.

The composition of the auxiliary material 3 contains an oxide or an oxide and a halide, and the auxiliary material 3 participates in the molten pool reaction to adjust the workpiece (metal member, product) component, and thus can be added to the auxiliary material according to the composition and efficiency requirements of the metal member to be formed. Alloy powder and/or elemental metal powder reduce production costs.

Further, in the step C, the operation of recovering the residual excipients and removing the slag shell 7 formed by solidification of the slag pool 8 may be attached. When removing, the machine removal or manual removal operation can be started 400 mm to 500 mm behind the relative movement of the raw material yarn 1.

According to the electrofusion forming method of the present embodiment, the utilization rate of the raw material yarn is close to 100%; compared with the conventional processing technology (forging, casting, etc.), the number of manufacturing processes is small (no complicated heat treatment is required), the cycle is short, and the efficiency is high. The machining allowance of the components is very small, while reducing the finishing time and saving a lot of material.

[Examples]

This example describes the fabrication of CAP1400 nuclear power regulator by horizontal electrofusion forming method. The overall forming process of the cylinder body, in the conventional process, the inner wall of the cylinder is welded with a thickness of 308 stainless steel layer of about 8 mm, and the wall thickness of the pressure regulator cylinder is about 125 mm. The equipment used includes:

(1) Slewing support table;

(2) fused power source;

(3) an electric fuse head;

(4) automatic wire feeding device;

(5) automatic conveying and auxiliary material recovery device for auxiliary materials;

(6) heating device;

(7) a cooling device;

(8) a substrate;

(9) Central control unit.

Fig. 2 is a schematic explanatory view showing the electrofusion forming method of the present embodiment, in which a device such as a power source or an automatic wire feeder is omitted. The material power parameters are as follows:

1) raw material wire 101 (C: 0.12-0.14%, other elements are consistent with SA508-3), diameter 4mm;

2) specially developed auxiliary material 301, the composition is 29.5% CaO+MgO; 30% AL2O3+MnO; 20.5% SiO2+TiO; 20% CaF2;

3) The number of electrofusion heads: 39 electrofusion heads 601, the electrofusion power source is a DC power source, the electrofusion head 601 is connected to the negative pole of the power source, and the substrate 201 is connected to the positive pole of the power source;

4) The electrofusion process parameters are: fused current 800A, fused voltage 38V, and relative movement speed of the fusion head 601 and the substrate 201 is 500-600 mm/min (melting tank moving speed).

The annular metal member is fabricated by a metal member electrofusion forming method, and the implementation steps are as follows:

(1) The axis of the cylindrical base material 201 is horizontally arranged and supported on a slewing support table, and 39 electrofusible heads are evenly arranged laterally at a pitch of about 300 mm (the central control device determines the precise position and movement). Above the material 201, and adjusting the distance between each electrofusion head and the surface (outer peripheral surface) of the substrate 201, and selecting the electric melting point;

(2) feeding the raw material wire 101 and the auxiliary material to the surface of the substrate 201, starting the power source, introducing a high-energy heat source, melting the raw material wire and the auxiliary material, and rotating the substrate 201 to start the first layer of the first layer of each electrofusion head ( Electrolytic deposition of each layer consisting of a plurality of axially aligned channels;

(3) When a distance is formed between the electrofusion head 601 and the electrofusion starting point, the auxiliary material recovery device is started to take back the unmelted auxiliary material, expose the slag shell and remove it, so as to facilitate the next fused deposition (stacking) Then, the cooling device or the heating device is started to cool or heat the fused deposition metal, and the temperature of the substrate (the first layer refers to the substrate 201, and the other layer refers to the former layer of the deposited metal) is controlled at 200 ～. 300 ° C;

(4) When the substrate 201 is rotated one turn to complete the first fused deposition, under the control of the control device, all the fused heads 201 are simultaneously moved linearly to the left by 3/4 of the melt width, and the respective fusion fused heads are adjusted. The distance between 601 and the surface of the substrate 201 is to ensure the stability of the electrofusion, and then the electrofusion deposition of the second layer of the first layer is started, and the overlap between the left and right turns is ensured in the process;

(5) After the completion of the second pass, repeat step (4) to complete the formation of the other fused deposition track. When the last pass is reached, the last end point of the adjacent fused fuse head is matched with the first start point. Good connection, to complete the first layer of fused deposition;

(6) After completing the first layer of fused deposition, all the electrofusion heads automatically raise the height of one layer of deposition (ie, after the layer), and begin the first fused deposition of the second layer, the first layer of the fuser The end point of the second layer is the starting point of the first track of the second layer;

(7) When the first fused deposition of the second layer is completed, all the electrofusion heads are simultaneously moved linearly to the right by 3/4 of the melt path, and the electrofusion heads automatically adjust the distance between them and the substrate to ensure the distance. The stability of the fused, starting the second layer of fused deposition of the second layer, so that the left and right loops are well lapped;

(8) When the completion of the second layer of the second fused deposition is completed, repeat step (7), and then complete the other fused deposition track. When the last pass is reached, the last end point of the adjacent fused head is The first starting point should be well connected, and the second layer of electricity should be completed. Melt deposition

(9) Repeat steps (6) to (8) to complete other electrofusion deposition layers. In this process, the direction of movement of the adjacent electrofusion deposition layer of the electrofusion head may be reversed, and finally continuous electrofusion deposition forms a voltage regulator. Cylinder.

After the electrofusion forming, the stainless steel substrate 201 becomes a part of the pressure regulator cylinder, which realizes the direct connection forming of the dissimilar materials, thereby changing the manufacturing process of the 308 stainless steel which is deposited on the inner wall of the forged SA508-3 cylinder after the conventional process. The method reduces the number of process steps, improves work efficiency and quality, and can also be removed by ordinary carbon steel in subsequent machining.

According to the conventional forging process, the regulator cylinder is divided into three sections (upper, middle and lower three sections), which are respectively forged and then integrally welded, and in this embodiment, a plurality of (39) electrofusion heads are arranged side by side. The overall forming greatly improves the forming efficiency; naturally, the number and arrangement of the electric melting heads can be adjusted according to customer requirements, and the forming is segmented.

Claims

A nuclear power plant voltage regulator cylinder electrofusion forming method, characterized in that:

The method adopts a high-energy heat source formed by arc heat, electric resistance heat and electroslag heat, melts the continuously conveyed metal raw material wire, and solidifies and builds the metal member layer by layer on the substrate;

The electrofusion head and the substrate are connected to the two poles of the power source, and the metal raw material wire is sent to the surface of the substrate through the conveying mechanism and the electrofusion head during the forming, and an arc is generated between the raw material wire and the substrate under the deposition protection of the granular auxiliary material. The molten part of the piled auxiliary material forms a molten slag pool, the electric current flows through the raw material wire material and the molten auxiliary material slag pool to form electric resistance heat and electroslag heat, and the raw material wire is made under the action of three heat composite high energy heat sources of arc heat, electric resistance heat and electroslag heat. The material is melted, a local molten pool is formed on the surface of the substrate, and the raw material wire and the auxiliary material are continuously conveyed. According to the layered slice data of the shaped member, the relative movement of the electrofusion head and the substrate is controlled by a computer to realize the rapid melting of the molten pool on the substrate. The cooling is solidified layer by layer, and finally the voltage regulator cylinder is stacked layer by layer.
The nuclear power plant voltage regulator cylinder electrofusion forming method according to claim 1, wherein:

Depending on the type of nuclear power unit, the formed evaporator barrel has a diameter of 2-3 m and a length of 3-12 m.
The nuclear power plant voltage regulator cylinder electrofusion forming method according to claim 1, wherein:

The raw material wire is prepared according to the SA508Gr3Cl2 material standard in ASME or the 18MnD5 material standard in RCC-M or other corresponding standards. The wire diameter is 2-8mm, the C content is 0.11-0.15%, and the workpiece C content after forming is 0.05-0.10%, the workpiece grain Degree Grade 9-10.
The nuclear power plant voltage regulator cylinder electrofusion forming method according to claim 1, wherein:

According to the diameter of the wire, the current in the power supply parameter is 200A ~ 2000A, the voltage is 20V ~ 50V, the power supply is DC or AC power, when the DC power supply is used, the electrofusion head is connected to the positive or negative pole.
The nuclear power plant voltage regulator cylinder electrofusion forming method according to claim 1, wherein:

The substrate or the deposited metal is heated or cooled according to the requirements of the formed workpiece, and the surface temperature of the controlled substrate or the deposited metal layer is 120 to 450 °C.
The nuclear power plant voltage regulator cylinder electrofusion forming method according to claim 1, wherein:

According to the size and efficiency requirements of the evaporator forming member, the number of the electric fusion heads is set to 1 to 100, and when the multiple electrofusion heads are arranged, the spacing of the adjacent electrofusion heads is 50 to 500 mm.
The nuclear power plant voltage regulator cylinder electrofusion forming method according to claim 1, wherein:

The substrate provides tooling support for the shaped workpiece, and has a cylindrical or cylindrical shape and a wall thickness of not less than 5 mm. The substrate material may be 308 stainless steel or other ordinary carbon steel or alloy steel. When it is 308 stainless steel, the substrate is retained as part of the formed workpiece after the workpiece is formed. When it is other ordinary carbon steel or alloy steel, it can be processed later. Removed.