Quenching cooling rate of the hottest aluminum all

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Quenching cooling rate of aluminum alloy quenching furnace

the cooling rate of aluminum alloy quenching furnace during quenching must ensure that the supersaturated solid solution is fixed and does not decompose. Make the skin appear young and compact, prevent the precipitation of strengthening phase, and reduce the mechanical properties after quenching and aging. Therefore, the faster the cooling speed during quenching, the better. However, the greater the cooling rate, the greater the residual stress and residual deformation of quenched products. Therefore, the cooling rate should be determined according to different alloys and products of different shapes and sizes

the quenching of general alloys is highly sensitive to the cooling rate, and the cooling rate should be selected. For example, the quenching cooling rate of 2A11 and 2A12 alloys should be more than 50 ℃/s, while 7A04 alloy is very sensitive to the cooling rate, and its quenching cooling rate is required to be more than 170 ℃/s

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for products with different shapes and sizes, different cooling rates should be adopted, usually mainly by adjusting the temperature of quenching medium. For simple shape, small and medium-sized bars, room temperature water quenching can be used (water temperature is generally 10 ~ 35 ℃), for complex shape and large wall thickness differences, 40 ~ 50 ℃ water quenching can be used. For products that are particularly prone to deformation, the water temperature can even be raised to 75 ~ 85 ℃ for quenching. The test shows that the mechanical properties and corrosion resistance of quenched products decrease with the increase of water temperature

the most commonly used quenching medium for aluminum alloy in aluminum alloy quenching furnace is water. Because the viscosity of water is small, the heat capacity is large, the evaporation heat is fast, the cooling capacity is strong, and the use is very convenient and economical. But its disadvantage is that the cooling capacity decreases after heating. The cooling of quenched and heated products in water can be divided into three stages: the first stage is film boiling stage. When the hot product just comes into contact with cold water, an uneven superheated steam film is immediately formed on its surface, which is very firm and has poor thermal conductivity, reducing the cooling speed of the product. The second stage is bubble boiling stage. When the steam film is destroyed, the liquid near the metal surface will produce intense boiling and strong heat exchange. The third stage is heat convection stage, cooling water circulation, or system 3 There is contact between the toothed bar pressing plate and the toothed bar swinging left and right, or moving up and down, which increases the convective heat exchange between the product surface and water, so as to improve the cooling speed

according to the above analysis, in order to quickly break through the first stage, take a step of cooling, and ensure the uniform cooling of quenched products, the company has the earliest academician workstation, postdoctoral workstation, and provincial engineering technology research center in Jurong City. It needs to be equipped with compressed air pipes in the quenching tank to facilitate mixing, and the products should swing appropriately after entering the tank. In addition, in order to ensure that the water temperature will not rise too much, the quenching tank should have sufficient capacity (generally more than 20 times the total volume of quenched products). Moreover, the cooling water should have a circulating device

in addition to adjusting the water temperature to control the quenching cooling rate of the aluminum alloy quenching furnace, different solvents can also be added to the cooling water to adjust the cooling capacity of the water. Usually, polyethanol aqueous solution is used as the cooling medium. At the same time, the concentration of polyethanol aqueous solution can be adjusted to control the cooling rate of quenching products. Generally, products that are easy to deform are often quenched with this kind of polyethylene glycol aqueous solution

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