Views:4 Author:Jia Hua Aluminium Co., Ltd Publish Time: 2019-06-03 Origin:Site
After quenching the hardness of aluminum alloy will have great improvement with the time extend. This is ageing. It’s one of the way improve the hardness of aluminum alloy.
As we know that, the front premise of ageing is quenching to get a saturated single phase structure is obtained. In the solid solution obtained by rapid quenching, not only the solute atoms are supersaturated, but also the vacancies (crystal point defects) are also supersaturated, that is, in a double super saturation state.
As the report say that the temperature of solution treatment higher, the greater the degree of super saturation after treatment.
The hardness will influence by the below.
1). Time: The best hardness will be the end of θ’’ to the beginning of θ’. In the end of θ’, the aluminum profiles will be soft. Therefore, we should keep the time at the end of θ’’ and the beginning of θ’ if we want the best ageing effect.
2). Temperature of quenching: quenching cold part but speed and quenching transfer time. The report show that the temperature of quenching, the time of quenching cold will be faster. The shorter the quenching intermediate transfer time, the greater the degree of super saturation of the solid solution obtained, and the greater the post-aging strengthening effect.
3). Temperature: Temperature will influence the hardness in . It will get the maxi hardness effect after reach a temperature. And this is the best ageing temperature. Different alloy will have a different ageing temperature.
Technology of Aging
Ageing can divide to two parts. One is the single level. And the other is grading aging.
Single-stage aging refers to an aging process carried out at room temperature or below 100 °C. The process is simple, but the uniformity of the structure is poor, and the tensile strength, yield strength, conditional yield strength, fracture property, stress corrosion resistance performance are difficult to obtain a good fit. Grading aging is two aging or multiple aging at different temperatures
The processing of aging
A). Curtain wall, normal window profiles, industrial profiles can be putted in the same Aging furnace. The temperature should be controlled at the range of 195℃±5℃. 3 hour finish after the temperature reach 195℃. And after the furnace is released, the fan blows for 20 minutes to cool, and the quality inspector checks the hardness.
B). Thermal break aluminum curtain wall profiles, Thermal break window profiles. The temperature should be at the range of 180℃±3℃. After the furnace is released, the fan blows for 20 minutes to cool, and the quality inspector checks the hardness.
C). When the temperature of furnace reaches the required temperature of technology, we should test temperature it every 30 minute.
Precautions of aging
a). We should try to make the profiles in ageing furnace with the similar material, same thickness, same size, and required hardness. What’s more, we should strictly follow the required steps.
b). We should pay attention to the observation of the circulating fan, circulating cooling water operation, pay close attention to the observation of the ignition heating situation, the temperature rise error in the furnace, the heating rate in the furnace, the heat preservation condition, and pay attention to the lifting safety and sealing of the furnace door.
c). It must be cared the Leakage situation of oil and air. We must make sure 100% safety.
d). It is strictly forbidden to stay in the aluminum aging furnace. It must be properly protected when entering the furnace, and must be observed and protected by adults. It is forbidden to carry inflammable and explosive materials in the furnace, and is strictly prohibited for non-productive purposes such as baking, heating and sleeping. The profiles with different post-processing requirements shall not be combined and framed, and shall be transferred to the production departments according to the post-processing requirements and the process card (manufacturing subpoena). Make a record of each form of the process for verification. The handover class must be clearly stated in person.
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