CN105965176B - For soldering tungsten-copper alloy and the Ni base chilling solders and soldering processes of stainless steel - Google Patents

Abstract

The invention discloses a Ni-based quenching filler material and a brazing process for brazing tungsten-copper alloy and stainless steel, comprising the following steps: (1) cleaning the surface of W-Cu alloy and stainless steel to be brazed by metallographic sandpaper; Use W3.5 metallographic sandpaper to grind and clean both sides of the Ni-based quenched solder that will be used for brazing. After grinding, put W-Cu alloy, stainless steel and Ni-based quenched solder together in acetone, and use ultrasonic cleaning (2) Place the cleaned Ni-based quenched solder between the W-Cu alloy and the stainless steel surface to be welded, control the brazing gap to 15-25 μm, and fit it tightly in a special brazing fixture ; (3) Place the assembled jig as a whole in a brazing furnace with a vacuum degree not lower than 6×10 ^‑4 Pa, and then braze according to the following process curve. The Ni-based quenching solder provided by the invention has a narrow melting temperature range and short solder melting time, which is beneficial to improving brazing efficiency, and Ni element can undergo certain solid solution reaction with W, Cu, Fe, Cr and other elements.

Description

Ni-based quenching filler metal and brazing process for brazing tungsten-copper alloy and stainless steel

technical field

The invention relates to a Ni-based quenching filler material and a brazing process for brazing tungsten-copper alloy and stainless steel, belonging to the technical field of heterogeneous material welding.

Background technique

As tungsten-copper alloys are increasingly used in high-temperature structural parts, composite parts made of tungsten-copper alloys and stainless steel are becoming more and more popular in the market. Tungsten-copper alloy and stainless steel dissimilar materials are often connected because of the large difference in linear expansion coefficient, melting point and thermal conductivity between the two, and the composite parts are subjected to cyclic thermal loads during the preparation and use, and stress concentration is prone to occur at the joints. Increase the fracture tendency and reduce the mechanical properties of the weld metal. In addition, tungsten-copper alloy is sensitive to gas impurities, and holes are easily formed at the welding interface, and the weld structure is brittle, which affects the airtightness and bearing capacity of the joint. Therefore, the design of the welding master alloy and the structural changes caused by cyclic thermal loads and the failure of weld performance caused by gas impurity contamination and welding stress are the main problems facing the welding of dissimilar materials such as tungsten-copper composite materials and stainless steel.

Due to its special process characteristics, brazing has the advantages of little influence on the base metal, and small stress and deformation of weldments. As an important welding technology, brazing has unique advantages for the connection of new materials, especially for the connection of refractory materials and dissimilar materials. Vacuum brazing technology is a better method to prevent tungsten-copper alloy from being polluted by gas impurities because it brazes materials in a vacuum environment. Chinese patent No. 201210158935.3 discloses a vacuum brazing process for brazing tungsten-copper alloy and stainless steel by using Ti-Fe-Zr-Cu based brazing material. Compared with Ti-Fe-Zr-Cu based solder, the Ni-based quenched solder provided by the invention has the advantages of narrow solder melting temperature range, short solder melting time, etc., which is beneficial to improve brazing efficiency. In addition, the use of Ni-based solder to braze tungsten-copper and stainless steel, the brazed joint has good oxidation resistance and corrosion resistance, which is more conducive to expanding the application range of tungsten-copper alloy. The Chinese patent No. 201510126420.9 discloses a vacuum brazing process using Zr-based solder to braze tungsten-copper alloy and stainless steel. The wettability and seam filling are poor, and the quality of the brazed joint is not high. The Chinese patent No. 201510687945.X discloses a method for preparing a tungsten-copper alloy and stainless steel integral material, which is cumbersome and complicated.

Contents of the invention

Purpose of the invention: in order to overcome the deficiencies in the prior art, the present invention provides a kind of Ni-base quenching solder and brazing process for brazing tungsten-copper alloy and stainless steel, the method adopts Ni-base quenching solder to tungsten-copper alloy and stainless steel Stainless steel is used for vacuum brazing process. The Ni-based quenching solder provided has the advantages of narrow melting temperature range, short melting time, good oxidation resistance and corrosion resistance, and can obtain high-strength joints with dense structure; the provided vacuum brazing process does not require The addition of brazing flux and other protective measures is convenient and quick to implement, and the preparation of the brazing material and the brazing process can be repeated and reproduced, which is convenient for popularization and application.

Technical solution: In order to solve the above technical problems, a Ni-based quenching filler metal for brazing tungsten-copper alloy and stainless steel according to the present invention, the mass percentage of Ni-based quenching filler metal is composed of: Mn 20.0-25.0%, Si 3.0-5.0% %, Cu 3.5-5.5%, Zr 0.6-0.9%, and the balance is Ni.

Preferably, the mass percentage composition of the Ni-based quenching solder is: Mn 23.0%, Si 4.0%, Cu 5.0%, Zr 0.8%, and the balance is Ni.

Preferably, the Ni-based quenched solder is in the shape of a foil with a thickness of 50-80 μm.

A brazing process for tungsten-copper alloy and stainless steel, comprising the following steps:

(1) Use W28~W3.5 metallographic sandpaper to clean the surface of W-Cu alloy and stainless steel to be brazed, focusing on cleaning impurities, oil stains and oxide films on the surface to be brazed; use W3.5 metallographic sandpaper Grind and clean both sides of the Ni-based quenched solder that will be used for brazing. After grinding, put the W-Cu alloy, stainless steel and Ni-based quenched solder together in acetone, and use ultrasonic cleaning for 15-20 minutes before drying. ;

(2) Place the cleaned Ni-based quenched solder between the W-Cu alloy and the stainless steel surface to be welded, control the brazing gap to 15-25 μm, and fit it tightly in a special brazing fixture to ensure the accuracy of the connection. Place an indenter of rated mass on the fixture;

(3) Place the assembled jig as a whole in a brazing furnace with a vacuum degree not lower than 6×10 ^-4 Pa, and then braze according to the following process curve:

a) Heating at 8-12°C/min to 300-350°C, keeping at this temperature for 15-20min;

b) Continue heating at 5-10°C/min to 750-850°C, and keep warm at this temperature for 15-20min;

c) Continue heating at 7-13°C/min to the brazing temperature of 1020-1035°C, and keep warm at the brazing temperature for 15-20min;

d) at 5-8°C/min; cooling rate to 400-600°C;

e) After the program runs, turn off the heating, and the weldment is cooled with the furnace, and the weldment is taken out after the temperature of the vacuum chamber is cooled to below 100°C.

As preferably, the Ni-based quenching solder used in the step (1) has a thickness of 50-80 μm,

Preferably, the mass percentage composition of Ni-based quenching solder in the step (1) is: Mn 20.0-25.0%, Si 3.0-5.0%, Cu 3.5-5.5%, Zr 0.6-0.9%, and the balance is Ni.

As a preference, the mass percentage composition of Ni-based quenching solder in the step (1) is: Mn 23.0%, Si 4.0%, Cu 5.0%, Zr 0.8%, and the balance is Ni.

Preferably, in the step (2), placing an indenter of rated mass on the jig produces a constant vertical pressure of 0.01-0.04 MPa.

Preferably, in the step (2), a stainless steel sheet with a thickness of 15-25 μm is placed between the brazing filler metal and the stainless steel base material.

The Ni-based quenching brazing filler metal prepared by the invention can make the brazing filler metal have good brazing process performance by rationally adding various alloy elements, and meet the performance requirements of W-Cu alloy and stainless steel brazing joints in complex environments. Adding an appropriate amount of Mn element can improve the mechanical properties of brazing joints through solid solution; adding an appropriate amount of Si element can reduce the melting point of the solder and improve wettability; adding an appropriate amount of Cu element can improve the plasticity and strength of the alloy solder , improve the wettability of the brazing filler metal to the base metal, promote the solid solution metallurgical reaction between the brazing filler metal and the base metal, and improve the overall performance of the brazed joint; adding an appropriate amount of Zr element can refine the grain, improve the joint strength, toughness and resistance Corrosivity; at the same time, a large amount of Ni element in the solder can not only improve the wettability of the solder to the base metal, but also improve the strength of the joint and the oxidation and corrosion resistance through the solid solution reaction with the base metal elements.

The brazing process provided by the present invention is to first put W-Cu alloy, Ni-based quenching solder and stainless steel into a special brazing fixture in a butt joint mode, and then put the sample and the fixture together into a vacuum furnace to complete brazing. The vacuum environment and reasonable process parameter setting make the whole component free from deformation, micro cracks, pores and inclusions and other defects, which is helpful to obtain brazed joints with good mechanical properties.

Beneficial effect: compared with the prior art, the present invention has the following advantages:

(1) The Ni-based quenching solder provided by the present invention has a narrow melting temperature range and short solder melting time, which is conducive to improving brazing efficiency, and the Ni element can have a certain solid solution reaction with W, Cu, Fe, Cr and other elements , which is conducive to the wetting and filling of the two base metals by the Ni-based quenching filler metal, and finally can form a brazed joint with dense structure and high strength.

(2) Nickel-based brazing filler metal is a general-purpose multifunctional brazing filler metal. It is used to braze tungsten-copper and stainless steel. The joint has good oxidation resistance and corrosion resistance, which expands the application occasions of tungsten-copper alloy.

(3) The vacuum brazing process provided by the present invention does not need to add brazing flux and other protective measures, and the high vacuum environment cooperates with reasonable process parameter settings, so that the whole component has no deformation, no defects such as microscopic cracks, pores and inclusions, which contributes to A brazed joint with good mechanical properties is obtained.

Description of drawings

Fig. 1 is the structural schematic diagram of the brazing structure of specific embodiment 1;

Fig. 2 is the scanning electron micrograph of the brazed joint that concrete implementation 1 obtains;

Fig. 3 is a photograph of the microscopic morphology of the shear fracture of the brazed joint obtained in Embodiment 1.

detailed description

Example 1

Choose W55-Cu alloy and austenitic stainless steel for butt joint vacuum brazing. Among them, the size of W55-Cu alloy and austenitic stainless steel sample is 20mm×20mm×5mm, and the surface to be brazed is 20mm×5mm.

The thickness of the Ni-based quenching solder used is 50 μm, and the mass percent composition is: Mn 23.0%, Si 4.0%, Cu 5.0%, Zr 0.8%, and the balance is Ni.

A brazing process for tungsten-copper alloy and stainless steel, comprising the following steps:

(1) Use W28~W3.5 metallographic sandpaper to clean the surface of W-Cu alloy and stainless steel to be brazed, focusing on cleaning impurities, oil stains and oxide films on the surface to be brazed; use W3.5 metallographic sandpaper Grind and clean both sides of the Ni-based quenched solder that will be used for brazing. After grinding, put the W-Cu alloy, stainless steel and Ni-based quenched solder together in acetone, and use ultrasonic cleaning for 15-20 minutes before drying. ;

(2) Place the cleaned Ni-based quenched solder between the W-Cu alloy and the stainless steel surface to be welded, control the brazing gap to 20 μm, and fit it tightly in the special brazing fixture to ensure the accuracy of the connection. Place an indenter of rated mass on it to generate a constant vertical pressure of 0.02MPa, as shown in Figure 1;

(3) Place the assembled jig as a whole in a brazing furnace with a vacuum degree not lower than 6×10 ^-4 Pa, and then braze according to the following process curve:

a) Heating to 300°C at 10°C/min;

b) Insulate at this temperature for 15 minutes, the purpose is to fully carry out the degassing process on the surface or inside of the base metal and solder;

c) Continue heating to 800°C at 7°C/min;

d) Keep warm at this temperature for 15 minutes, the purpose is to avoid excessive thermal inertia and ensure temperature control accuracy;

e) Continue heating at 11°C/min to the brazing temperature of 1025°C;

f) Keep warm at the brazing temperature for 15 minutes, the purpose is to fully carry out the brazing process and prevent welding defects such as incomplete brazing;

g) cooling to 500°C at 7°C/min;

h) After the program runs, turn off the heating, and the weldment is cooled with the furnace, and the weldment is taken out after the temperature of the vacuum chamber is cooled to below 100°C.

Experimental results: The joint between the obtained W55-Cu alloy and austenitic stainless steel is beautifully formed, as shown in Figure 2 and Figure 3. Scanning electron microscope observation shows that the solder has good wettability to the base metal on both sides, and the brazing interface forms a dense Excellent interfacial bonding, no defects such as microcracks and pores, and the shear strength at room temperature is 275MPa.

Example 2

Choose W55-Cu alloy and austenitic stainless steel for butt joint vacuum brazing. Among them, the size of W55-Cu alloy and austenitic stainless steel sample is 20mm×20mm×5mm, and the surface to be brazed is 20mm×5mm.

The thickness of the Ni-based quenching solder used is 70 μm, and the mass percent composition is: Mn 21.0%, Si 3.0%, Cu 4.0%, Zr 0.6%, and the balance is Ni.

A brazing process for tungsten-copper alloy and stainless steel, comprising the following steps:

(1) Use W28~W3.5 metallographic sandpaper to clean the surface of W-Cu alloy and stainless steel to be brazed, focusing on cleaning impurities, oil stains and oxide films on the surface to be brazed; use W3.5 metallographic sandpaper Grind and clean both sides of the Ni-based quenched solder that will be used for brazing. After grinding, put the W-Cu alloy, stainless steel and Ni-based quenched solder together in acetone, and use ultrasonic cleaning for 15-20 minutes before drying. ;

(2) Place the cleaned Ni-based quenched solder between the W-Cu alloy and the stainless steel surface to be welded, control the brazing gap to 15 μm, and fit it tightly in the special brazing fixture to ensure the accuracy of the connection. Place an indenter of rated mass on it to produce a constant vertical pressure of 0.03MPa;

(3) Place the assembled jig as a whole in a brazing furnace with a vacuum degree not lower than 6×10 ^-4 Pa, and then braze according to the following process curve:

a) Heating to 350°C at 12°C/min;

b) Insulate at this temperature for 20 minutes, the purpose is to fully carry out the degassing process on the surface or inside of the base metal and solder;

c) Continue heating to 850°C at 5°C/min;

d) Keep warm at this temperature for 20 minutes, the purpose is to avoid excessive thermal inertia and ensure temperature control accuracy;

e) Continue heating at 10°C/min to the brazing temperature of 1030°C;

f) Keep warm at the brazing temperature for 20 minutes, the purpose is to fully carry out the brazing process and prevent welding defects such as incomplete brazing;

g) cooling to 600°C at 5°C/min;

h) After the program runs, turn off the heating, and the weldment is cooled with the furnace, and the weldment is taken out after the temperature of the vacuum chamber is cooled to below 100°C.

Experimental results: The joint between the obtained W55-Cu alloy and austenitic stainless steel is beautifully formed. The scanning electron microscope observation shows that the solder has good wettability to the base metals on both sides, and the brazing interface forms a dense interface bond without microcracks and pores. and other defects, the shear strength at room temperature is 249MPa.

Example 3

Choose W55-Cu alloy and austenitic stainless steel for butt joint vacuum brazing. Among them, the size of W55-Cu alloy and austenitic stainless steel sample is 20mm×20mm×5mm, and the surface to be brazed is 20mm×5mm.

The thickness of the Ni-based quenching solder used is 80 μm, and the mass percent composition is: Mn 25.0%, Si 5.0%, Cu 5.5%, Zr 0.9%, and the balance is Ni.

A brazing process for tungsten-copper alloy and stainless steel, comprising the following steps:

(1) Use W28~W3.5 metallographic sandpaper to clean the surface of W-Cu alloy and stainless steel to be brazed, focusing on cleaning impurities, oil stains and oxide films on the surface to be brazed; use W3.5 metallographic sandpaper Grind and clean both sides of the Ni-based quenched solder that will be used for brazing. After grinding, put the W-Cu alloy, stainless steel and Ni-based quenched solder together in acetone, and use ultrasonic cleaning for 15-20 minutes before drying. ;

(2) Place the cleaned Ni-based quenched solder between the W-Cu alloy and the stainless steel surface to be welded, control the brazing gap to 25 μm, and fit it tightly in the special brazing fixture to ensure the accuracy of the connection. Place an indenter of rated mass on it to produce a constant vertical pressure of 0.04MPa;

(3) Place the assembled jig as a whole in a brazing furnace with a vacuum degree not lower than 6×10 ^-4 Pa, and then braze according to the following process curve:

a) Heating to 300°C at 8°C/min;

b) Insulate at this temperature for 15 minutes, the purpose is to fully carry out the degassing process on the surface or inside of the base metal and solder;

c) Continue heating to 850°C at 9°C/min;

d) Keep warm at this temperature for 20 minutes, the purpose is to avoid excessive thermal inertia and ensure temperature control accuracy;

e) Continue heating at 13°C/min to the brazing temperature of 1035°C;

f) Keep warm at the brazing temperature for 20 minutes, the purpose is to fully carry out the brazing process and prevent welding defects such as incomplete brazing;

g) cooling to 400°C at 8°C/min;

h) After the program runs, turn off the heating, and the weldment is cooled with the furnace, and the weldment is taken out after the temperature of the vacuum chamber is cooled to below 100°C.

Experimental results: The joint between the obtained W55-Cu alloy and austenitic stainless steel is beautifully formed. The scanning electron microscope observation shows that the solder has good wettability to the base metals on both sides, and the brazing interface forms a dense interface bond without microcracks and pores. and other defects, the shear strength at room temperature is 271MPa.

In order to facilitate comparison with the above-mentioned embodiments, five groups of comparative examples are made: each comparative example is different from Example 1 only in the composition of the Ni-based quenching solder, and the other welding processes are the same. Table 1 lists the mass percent of the brazing filler metal in each comparative example and the performance parameters of the joint after welding.

Table 1

Through Examples 1 to 3 and Comparative Examples 1 to 5, the effect of the Mn element in the Ni-based solder is mainly to generate a solid solution reaction with the Cu element in the base metal to generate a Cu (Mn) solid solution, thereby improving the brazing performance. Mechanical properties of joints. In Comparative Example 1 containing no Mn element, it can be found that the shear strength of the brazed joint is low. The role of Si element in Ni-based solder is mainly to reduce the melting point of the solder and provide the wettability of the solder. In Comparative Example 2 that does not contain Si element, it can be found that the wettability of the solder is average, and discontinuous defects of the brazing seam are found in the joint after welding. The role of Cu element in Ni-based solder is to improve the wettability of Ni-based solder; the second is to have a solid solution reaction with Ni, Mn, and Fe elements to improve the mechanical properties of the joint. In Comparative Example 3 that does not contain Cu, it can be found that the wettability of the joint is average and the shear strength is low. The effect of adding an appropriate amount of Zr element in Ni-based solder is mainly to refine the grains and improve the plasticity and toughness of the joint. In Comparative Example 4 that does not contain Zr element, it can be found that the shear strength of the joint is much lower than that in Example 1. The role of Ni, the main element in Ni-based solder, is to improve the wettability of the solder to the base metal; the second is to have a solid solution reaction with W, Cu, Fe, Cr and other elements in the base metal to improve the mechanical properties of the joint. and oxidation resistance. In Comparative Example 5, due to the low content of Ni element in the brazing filler metal system, the primary problem brought is that the brazing filler metal has poor wettability to the base metal, especially the wettability on the stainless steel side is very poor, thus Leading to unbrazed joints. In addition, due to the excessive content of Si and Zr elements, a large number of brittle compounds will be formed in the joint, which greatly reduces the mechanical properties of the joint.

The above is only a preferred embodiment of the present invention, it should be pointed out that for those of ordinary skill in the art, without departing from the principle of the present invention, some improvements and modifications can also be made, and these improvements and modifications are also possible. It should be regarded as the protection scope of the present invention.

Claims (8)

1. A Ni-based quenching filler metal for brazing tungsten-copper alloy and stainless steel is characterized in that: the Ni-base quenching filler metal is composed of the following components according to the following mass percentages: Mn 20.0 ~ 25.0%, Si 3.0 ~ 4.0% , Cu 3.5~5.5%, Zr 0.6~0.9%, and the balance is Ni. 2. the Ni-based quenching solder for brazing tungsten-copper alloy and stainless steel according to claim 1 is characterized in that: the mass percentage of Ni-based quenching solder consists of: Mn 23.0%, Si 4.0%, Cu 5.0% , Zr 0.8%, the balance is Ni. 3. The Ni-based quenching solder for brazing tungsten-copper alloy and stainless steel according to claim 1, characterized in that: the Ni-based quenching solder is in the shape of a foil with a thickness of 50-80 μm. 4. a brazing process using the tungsten-copper alloy and stainless steel of the brazing filler metal according to claim 1, is characterized in that, comprises the following steps: (1) Use W28~W3.5 metallographic sandpaper to clean the surface of W-Cu alloy and stainless steel to be brazed, focusing on cleaning impurities, oil stains and oxide films on the surface to be brazed; use W3.5 metallographic sandpaper Grind and clean both sides of the Ni-based quenched solder that will be used for brazing. After grinding, put the W-Cu alloy, stainless steel and Ni-based quenched solder together in acetone, and use ultrasonic cleaning for 15-20 minutes before drying. ; (2) Place the cleaned Ni-based quenched solder between the W-Cu alloy and the stainless steel surface to be welded, control the brazing gap to 15~25μm, and fit it tightly in the special brazing fixture to ensure the accuracy of the connection. Place an indenter of rated mass on the fixture; (3) Place the assembled jig as a whole in a brazing furnace with a vacuum degree not lower than 6×10 ^-4 Pa, and then braze according to the following process curve: a) Heat at 8~12°C/min to 300~350°C, keep at this temperature for 15~20min; b) Continue heating at 5~10°C/min to 750~850°C, and keep at this temperature for 15~20min; c) Continue heating at 7~13°C/min to the brazing temperature of 1020~1035°C, and keep at the brazing temperature for 15~20min; d) Cool to 400~600°C at a cooling rate of 5~8°C/min; e) After the program runs, turn off the heating, and the weldment is cooled with the furnace, and the weldment is taken out after the temperature of the vacuum chamber is cooled below 100°C. 5. The brazing process of tungsten-copper alloy and stainless steel according to claim 4, characterized in that: the Ni-based quenching solder used in the step (1) has a thickness of 50-80 μm. 6. The brazing process of tungsten-copper alloy and stainless steel according to claim 4, characterized in that: in the step (1), the mass percentage of Ni-based quenched solder is composed of: Mn 23.0%, Si 4.0%, Cu 5.0 %, Zr 0.8%, and the balance is Ni. 7. The brazing process of tungsten-copper alloy and stainless steel according to claim 4, characterized in that: in the step (2), placing an indenter of rated mass on the fixture produces a constant vertical pressure of 0.01-0.04 MPa. 8. The brazing process of tungsten-copper alloy and stainless steel according to claim 4, characterized in that: in the step (2), a stainless steel sheet with a thickness of 15-25 μm is placed between the brazing material and the stainless steel base material.