The aluminum water tank
is composed of a fluid conduit and radiator fins. The conduit is made of aluminum alloy plate and welded by a high-frequency pipe welding machine. The conduit and fins are brazed into a whole through the cooling medium to form the main body of the water tank. After the automatic brazing of the aluminum water tank
in a high-temperature special furnace at about 600 ℃, the welding between the conduit and radiator fins shall be firm, and the conduit shall not be deformed under high temperature, otherwise It is not good for heat dissipation to produce faulty welding or desoldering. Therefore, the quality of the composite aluminum plate for aluminum water tank
has a direct impact on the quality of the aluminum water tank.
In general, the ability of aluminum plate to resist gravity natural sagging in the process of brazing is called the anti sagging performance of the material, and the natural sagging distance (mm) is called the sag, which is one of the main indicators to measure the performance of composite materials.
The device for measuring the sagging of composite heat exchange composite materials is a test method recommended by Japan low temperature welding Committee. One end of the composite aluminum foil plate is fixed on the device and the other end is suspended outside the support rod, which is made of stainless steel. The distance from the support rod to the cantilever end of the sample is 50mm. The sagging of the sample is measured after it is kept in a 600 ℃ martensitic furnace for a certain period of time (5min). The anti sagging property of the alloy is related to the cold working property of the material and the annealing softening temperature. When the cold working rate is fixed, the higher the softening annealing temperature is, the more serious the sagging is, and when the annealing temperature is fixed, the better the cold working rate is controlled at 20% ~ 40%. In addition, the addition of Zr to the core alloy can improve the sag resistance.
Chalco is a famous aluminum manufacturer in China. Sun Hai'an, a researcher of Chalco, shows that the relationship between the sag resistance of aluminum plate for aluminum water tank
and the softening annealing temperature of the finished product before cold rolling is that the temperature is high, and the sag value is large. The sag of composite aluminum plate under the brazing temperature is caused by the diffusion and erosion of Si atom to the core material, which makes the actual thickness of the core material thinner, and the cold processing rate The structure energy of 20% ~ 40% composite aluminum plate can organize the diffusion of Si atom to the core, which is a strong anti sagging property of the material. Therefore, controlling and reducing the diffusion of Si atom to the core is one of the key measures to improve the anti sagging property of the material.