Copper and stainless steel dissimilar metal water adapter vacuum brazing technology method

A technology of dissimilar metals and brazing technology, applied in metal processing equipment, welding/welding/cutting items, manufacturing tools, etc., can solve the problems of large differences in melting point, thermal conductivity and linear expansion coefficient, etc., and achieve reliable and improved methods The effect of high product qualification rate and high production efficiency

Active Publication Date: 2008-06-18

NUCLEAR POWER INSTITUTE OF CHINA

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AI-Extracted Technical Summary

Problems solved by technology

Due to the special structure of the water joint, the stainless steel water box needs to be welded with different metals with the copper lining pipe and the copper L support respectively. These two metal materials are obviously diffe...

Method used

And copper L support bottom distance a is increased by 1mm by original 46mm, and foil-like silver-copper-palladium brazing filler metal is changed into monolithic type by two pieces of split structure, so that corrosion occurs after avoiding copper L support and stainless steel water box welding .

Stainless steel water box and red copper liner assembly gap (diameter difference) are 0.04mm-0.14mm, the red copper liner pipe 7 that meets gap requirement is vertically put into stainless steel water box 6, vertically successively at water box 6 top end faces Insert the foil-shaped silver-copper-palladium solder 5 and the water joint L support 1 to ensure that the contact surfaces are tightly fitted without gaps. Finally, between the inner surface of the stainless steel water box 6 and the copper lining pipe 7, an annular wire silver-copper-palladium brazing filler metal 4 is placed.

The structure of the stainless steel water box can also be improved, and the top structure of the water box is changed into a straight section and added with an inner chamfer by the inner chamfer, so as to ensure that the annular wire silver...

Abstract

The invention discloses a vacuum brazing technology method between copper and stainless steel dissimilar metal water connector, comprising processing each part of the water connectior, controling the processing precision and component assembly clearance; washing the part of water connectior; assembling water connections and putting in special fixture. Put the fixture in vacuum brazing furnace and carry out braze welding according to the following brazing technology: 1) take 35 minutes to make the furnace temperature to rise to 650 DEG C at a uniform speed; 2) continue to preserve heat for 20 minutes; 3) rise the furnace temperature at a uniform speed to 890 DEG C in 20minutes; 4) continue to preserve the heat for 20 minutes; 5) then rise the furnace temperature to 970 DEG C+-10 DEG C at a uniform speed in 15 minutes; 6) Continue to preserve heat for 5 minutes; 7) then stop heating and cool naturally; 8) on the next day take out the water connector from the fixture; 9) carry out the acceptance test by using the ultrasonic automatic testing device. The technical problem that the annular gap of the water connector is not fully filled and can be corroded is solved; the invention has the advantages of reliable method and high production efficiency, and can effectively improve the qualified rate of the products.

Application Domain

Soldering apparatusWelding/soldering/cutting articles +1

Technology Topic

Dissimilar metalBrazing +5

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Examples

Experimental program(1)

Example Embodiment

[0036] Embodiment: The vacuum brazing process for a water joint of copper and stainless steel dissimilar metals includes the following steps:

[0037] The first step is to process the various parts of the water joint, including the copper L support, the copper lining pipe, and the stainless steel water tank to control the processing accuracy and the assembly gap of related components. Taking into account the difference in melting point, thermal conductivity and linear expansion coefficient of copper and stainless steel vacuum brazing, when making stainless steel water tank and copper lined pipe, ensure that the assembly gap (diameter difference) is 0.04mm-0.14mm; processing copper When the L support and the stainless steel water box, ensure that the diameter of the inner hole of the L support matches the outer diameter of the top of the water box, and ensure the flatness of the horizontal mating surface, so that it is in close contact with the foil-shaped silver copper palladium solder during assembly , Seamless.

[0038] The second step is to clean the water joint parts. In order to ensure the quality of brazing of the water joint, chemical cleaning must be carried out before welding, and the parts of the water joint that meet the design requirements are cleaned:

[0039] Separate the parts into the ultrasonic cleaning machine, put the degreasing agent, and heat for ultrasonic cleaning for 1-2 hours;

[0040] Then put the ultrasonically cleaned parts into the configured chromic anhydride and sulfuric acid solution to emit light;

[0041] Finally, rinse with cold water for 10-15 minutes, soak in acetone for 15-30 minutes, and dry for later use.

[0042] The third step is to assemble the water joint components:

[0043] The assembly gap (diameter difference) between the stainless steel water tank and the copper lining is 0.04mm-0.14mm. Put the copper lining pipe 7 that meets the gap requirements into the stainless steel water tank 6 vertically, and put the foil on the top end of the water tank 6 vertically. The sheet-shaped silver copper palladium solder 5 and the water joint L support 1 ensure that the contact surface is tightly attached and seamless. Finally, a ring-shaped silver-copper-palladium solder 4 is placed between the inner surface of the stainless steel water box 6 and the copper lining tube 7.

[0044] In the fourth step, put the assembled water joint into a special water joint brazing fixture (see Figure 5). In order to ensure the quality of brazing between the copper L support 1 and the stainless steel hydration 6, a suitable size quartz glass sheet 2 and a weight 3 are placed on the upper surface of each water joint to be welded (see Figure 4).

[0045] The fifth step is to put the water joint along with the tooling into the ZRML-350 high-vacuum and gas-filled dual-purpose vacuum brazing furnace with internal heating vertical structure for brazing. The furnace body is heated by molybdenum sheets, and the working vacuum is 5×10 -3 Pa, the size of the uniform temperature zone is Ф350×500mm, and the FP21 intelligent temperature controller is used to control the heating, heat preservation and cooling process in the furnace.

[0046] Hang the tooling equipped with water joints in the uniform temperature zone of the vacuum brazing furnace, and close the vacuum brazing furnace to vacuum until the vacuum degree is better than 1×10 -2 It can be heated at Pa. When the vacuum degree is better than 1×10 -2 It can be heated at Pa. Perform vacuum brazing on the water joint according to the set temperature curve of the water joint brazing process, the process is as follows:

[0047] 1) The vacuum brazing furnace is heated linearly, and it takes 35 minutes to increase the furnace temperature from room temperature to 650℃ at a constant rate;

[0048] 2) When the furnace temperature reaches 650℃, perform the first stage of heat preservation for 20 minutes, so that the deflation process of the base material and the solder of the workpiece can be fully carried out, so that the brazing furnace can maintain a higher vacuum in the high temperature section in the future;

[0049] 3) When the first stage of heat preservation is over, perform rapid heating, and increase the furnace temperature from 650°C to 890°C at a uniform rate within 20 minutes;

[0050] 4) When the furnace temperature reaches 890℃, perform the second stage of heat preservation for 20 minutes to avoid excessive thermal inertia and ensure temperature control accuracy;

[0051] 5) After the second stage of heat preservation, the furnace temperature will be increased from 890℃ to 970℃±10℃ at a constant rate within 15 minutes;

[0052] 6) When the furnace temperature reaches 970℃±10℃, perform the third stage of heat preservation for 5 minutes to ensure sufficient solder diffusion and take into account the difference in the uniform temperature zone of the heating element;

[0053] 7) After the third stage of heat preservation, the vacuum brazing furnace stops heating and cools naturally with the furnace;

[0054] 8) Lift out the tooling from the vacuum brazing furnace the next day and take out the water joint;

[0055] 9) Use the ultrasonic automatic inspection device to check the quality of brazing of copper and stainless steel dissimilar metal water joints.

[0056] The structure of the stainless steel water box can also be improved. The top structure of the water box is changed from an inner chamfer to a straight section plus an inner chamfer, so as to ensure that the ring-shaped silver-copper-palladium solder is placed securely and will not be accidentally interfered during the brazing process. And the wrong position.

[0057] And the distance a from the bottom of the copper L support is increased by 1mm from the original 46mm, and the foil-like silver copper palladium brazing filler metal is changed from a two-piece split structure to an integral type to avoid dissolution after the copper L support and the stainless steel water tank are welded.

[0058] In this method, according to the size of the uniform temperature zone of the brazing furnace, special tooling (see Figure 5) is designed and processed to place the water joint. The tooling is divided into three layers, which are separated and supported by three support rods evenly distributed in the circumferential direction. The height between layers is set by the length of the uniform temperature zone. Each layer (see Figure 6) has radial openings from the inside to the outside according to the diameter of the water box. Twelve large holes are used to place the water joints, and the small holes ensure that the airflow is unblocked when vacuuming. The three lifting rods are welded to the support rod as a whole, and the top is connected in an umbrella shape for easy lifting. In order to avoid repeated heating and deformation during brazing, 4Cr25Ni20 stainless steel with sufficient thickness is selected for the placement layer to ensure sufficient high temperature strength.

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Copper and stainless steel dissimilar metal water adapter vacuum brazing technology method

AI-Extracted Technical Summary

Problems solved by technology

Method used

Abstract

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Example Embodiment

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Description & Claims & Application Information

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