6063 Vacuum Brazing

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6063 belongs to the Al-Mg-Si series alloy and has a wide range of applications. Especially the construction industry cannot do without this alloy. It is the most promising alloy. Good corrosion resistance, excellent weldability, good cold workability, and medium strength.

Because 6063 aluminum alloy has the advantages of high specific strength, high specific rigidity, light weight, corrosion resistance, and good electrical and thermal conductivity, and 6063 aluminum alloy is a heat-treatable and strengthened aluminum alloy, it can be heat-treated after welding to restore the strength, so It is widely used in aviation, aerospace, shipbuilding and other fields. A radar component has a thin-walled cavity structure. In order to reduce weight and increase strength, 6063 aluminum alloy is used. The part is symmetrically welded on both sides, and the welding surface is the entire contact surface. It is suitable for vacuum brazing. However, the solidus temperature of 6063 aluminum alloy is 615C, which is close to the melting point of the current brazing filler metal. The brazing temperature during the vacuum brazing process is equal to The holding time is difficult to determine
Certainly.

In order to realize the precision welding of radar thin-walled structural parts, vacuum brazing is used to weld the structural parts, and the influence of different heating and heat preservation processes on the welding quality is tested to obtain the best process parameters.

1. Chemical Composition

Al	margin
Si	0.20～0.6
Cu	≤0.10
Mg	0.45～0.9
Zn	≤0.10
Mn	≤0.10
Ti	≤0.10
Cr	≤0.10
Fe	0.000～0.350

2. 6063 Brazing Process

2.1. 6063 Vacuum Brazing Process

Solder cutting→removal of oxide film on the surface of brazing part base material and solder→fixing of brazing material→assembly→vacuum brazing→inspection.

2.2. Removal of Surface Oxide Film

Use sodium hydroxide aqueous solution to corrode the oxide film of the solder and the base material. The alkali corrosion reaction is slow at room temperature and requires a higher concentration. The corrosion rate is fast and difficult to control, and pitting is easy to occur. The corrosion time is long, and the thinning of the solder is more serious. The corrosion process that is easy to control is selected through comparative experiments: temperature 80 ℃ ~ 85 ℃, corrosion time 45s ~ 50s, after alkaline washing, rinse off lye and debris with clean water, remove corrosion products with dilute nitric acid, and rinse acid with water , Dehydrate with alcohol or acetone. The key parameters are the composition, concentration, corrosion temperature, corrosion time, concentration of the nitric acid solution, and the length of the corrosion time of the lye. If the composition and concentration of the lye are not properly selected, it is easy to cause incomplete removal of the oxide film or excessive corrosion. If the oxide film is not removed completely, the liquid solder will not be able to wet the base material well. Excessive corrosion of parts and solder may cause a certain degree of change in the composition ratio, or even a certain degree of change in the composition of the solder, which affects the wettability and welding strength of the two. In addition to the composition and concentration of the lye, the corrosion temperature and corrosion time also have an important impact on the removal effect. The appropriate oxide film removal process parameters need to be optimized through experiments. The corrosion rate of the solder and the base metal is different, and the corrosion of the solder and the base metal should be carried out separately.

2.3. Vacuum Brazing Heating

The heating rate of vacuum brazing has an important influence on the quality of brazing. The heating rate is fast, the surface color of the parts is dark, and the flatness is poor. The comparative experiment found that the heating effect in stages is better. During heating, the activity of aluminum is enhanced, and a very small amount of air can also oxidize it. At the same time, the gas expands by heating, reducing the heating rate, and the hot air can be extracted as much as possible; the heating rate is fast, and the other adverse effect is that the parts are easy to deform. Relying on radiation to transfer heat, rapid heating leads to uneven temperature, resulting in thermal stress or regional release of stress and deformation. It is necessary to raise the temperature quickly when it is close to the brazing temperature. The heating rate is slow, and the residence time in the solid-liquid line temperature range of the solder is long. In a vacuum environment, the low melting point components of the solder and the components with high vapor pressure volatilize severely, and the melting point of the remaining solder components is increased and maintained Solid state does not melt and cannot be brazed. This is the same situation that occurs when the brazing tool has a large heat capacity. As for the flatness of the parts, rapid heating at this stage is also allowed. The stress has been released at 500 ℃, the recrystallization temperature of 6063 is lower than 500 ℃, and the plasticity of aluminum alloy is good when the temperature is above 500 ℃, and the thermal stress is easily released. In the brazing experiment of the simulated test piece, the temperature is kept at 400 ℃ for 30 minutes and then quickly heated to 600 ℃ for 25 minutes, which is better than the brazing effect directly raised to 600 ℃. The result of further experiment is that a part brazed only at 450 ℃ for 30 minutes, and then raised to 620 ℃ at 10 ℃•min -1 is completely qualified.

2.4. 6063 Vacuum Brazing Insulation

Generally, the holding temperature is controlled to be lower than the solidus temperature of the parent material and higher than the liquidus temperature of the solder. If the temperature is too high, it is easy to produce the corrosion defects of the parent material. melt. The brazing holding time is about 2 minutes after the workpiece reaches the liquidus temperature of the solder. If the holding time is too short, the brazing seam is not full and smooth or even the solder is not completely melted; if the holding time is too long, the solder overflows or missed soldering. . The length of the holding time is affected by the heat capacity of the parts and tooling. The larger the heat capacity, the longer the holding time. The vacuum brazing of different parts and loading capacity requires experiments to screen out the brazing holding time.

2.5. 6063 Vacuum Brazing Cooling

The brazing holding time should not be too long. After the holding is completed, rapid cooling is required. The shielding gas is used to force uniform cooling. The best cooling rate is the degree of deformation of the parts to meet the requirements. Slow cooling is the same as extending the holding time, which will cause solder overflow or missing welding defects. For larger parts, rapid cooling is very important. When the heat capacity of parts and tooling is too large, even forced cooling of the gas cannot eliminate such defects and needs to be reduced. The amount of furnace installed.

3. Performance Indicators of Vacuum Brazing Furnace

Model	Effective Hot Zone Size (W*H*L)	Pressure rising rate	Loading Capacity	Ultimate pressure	MAX Temperature	Temp uniformity
RVB-335L-AL	300*300*500cm	0.5Pa/h	100Kg	6*10-4Pa	850℃	±3℃
RVB-446L-AL	400*400*600mm	0.5Pa/h	200Kg	6*10-4Pa	850℃	±3℃
RVB-557L-AL	500*500*700mm	0.5Pa/h	300Kg	6*10-4Pa	850℃	±3℃
RVB-669L-AL	600*600*900mm	0.5Pa/h	500Kg	6*10-4Pa	850℃	±3℃
RVB-8812L-AL	800*800*1200mm	0.5Pa/h	1000Kg	6*10-4Pa	850℃	±3℃
RVB-151535L-AL	1500*1500*3500mm	0.5Pa/h	1800Kg	6*10-4Pa	850℃	±5℃

Shanghai Geheng Vacuum Technology Co., Ltd. is a vacuum heat treatment furnace manufacturer with many years of experience in design, manufacturing and production. Mainly produce vacuum heat treatment furnace, vacuum sintering furnace, vacuum brazing furnace, New Energy And Environmental Protection Equipment and other vacuum equipments.Provide customized services, equipment work area can be based on customer output.