How to optimize aluminum extrusion and heat treatm

2022-10-02
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How to optimize aluminum extrusion and heat treatment process

for extrusion production, extrusion temperature is the most basic and key process factor. Extrusion temperature has a great impact on product quality, production efficiency, die life, energy consumption and so on

the most important problem of extrusion is the control of metal temperature. From the heating of ingot to the quenching of extruded profile, it is necessary to ensure that the soluble phase structure does not precipitate from the solid solution or show the dispersion and precipitation of small particles

6063 alloy ingot heating temperature is generally set within the temperature range of 2Si precipitation during the operation of Mg granulator. The heating time has an important impact on the precipitation of Mg2Si. Rapid heating can greatly reduce the possible precipitation time. Generally speaking, the heating temperature of 6063 alloy ingot can be set as: non homogenized ingot: ℃; Homogenization ingot: ℃

the extrusion temperature is adjusted according to different products and unit pressure during operation. During the extrusion process, the temperature of the ingot in the deformation zone changes. With the completion of the extrusion process, the temperature in the deformation zone gradually increases, and increases with the increase of the extrusion speed. Therefore, in order to prevent extrusion cracks, the extrusion speed should be gradually reduced as the extrusion process proceeds and the temperature in the deformation zone increases

2. Control the aluminum extrusion speed

the extrusion speed must be carefully controlled in the extrusion process. Extrusion speed has an important influence on deformation heat effect, deformation uniformity, recrystallization and solid solution process, mechanical properties of products and surface quality of products

if the extrusion speed is too fast, there will be pitting, cracks and other tendencies on the surface of the product. At the same time, too fast extrusion speed increases the non-uniformity of metal deformation. The outflow speed during extrusion depends on the type of alloy and the geometry, size and surface condition of the profile

the tedious installation is reduced.

6063 alloy profile extrusion speed (metal outflow speed) can be selected as M/min

with the progress of modern technology, the extrusion speed can be controlled by program or simulated program. At the same time, new technologies such as isothermal extrusion process and cadex have also been developed. By automatically adjusting the extrusion speed to keep the temperature in the deformation zone within a constant range, the purpose of rapid extrusion without cracks can be achieved

in order to improve production efficiency, many measures can be taken in the process. When using the hydraulic material testing machine in the handling process, what should be paid attention to? When using induction heating, there is a temperature gradient along the length of the ingot (gradient heating). During extrusion, the high-temperature end faces the extrusion die and the low-temperature end faces the extrusion pad, so as to balance part of the deformation heat; There are also water-cooled die extrusion, that is, the rear end of the die is forced to be cooled by water. The test shows that the extrusion speed can be increased by 30% - 50%, and the technology is also very clear

in recent years, nitrogen or liquid nitrogen has been used to cool dies (extrusion dies) abroad to increase extrusion speed, improve die life and improve the surface quality of profiles. In the extrusion process, nitrogen is introduced to the outlet of the extrusion die to release, which can make the cooled products shrink rapidly, cool the extrusion die and the metal in the deformation area, and take away the deformation heat. At the same time, the outlet of the die is controlled by the nitrogen atmosphere, which reduces the oxidation of aluminum and the bonding and accumulation of alumina. Therefore, the cooling of nitrogen improves the surface quality of products and greatly improves the extrusion speed. Cadex is a new extrusion process developed recently. It forms a closed-loop system based on the extrusion temperature, extrusion speed and extrusion pressure in the extrusion process, so as to maximize the extrusion speed and production efficiency, while ensuring the best performance

3. On machine quenching

6063-t5 quenching is to keep Mg2Si, which is solid soluble in the base metal at high temperature, after being quickly cooled to room temperature. The cooling rate is often proportional to the content of strengthening phase. The minimum cooling rate of 6063 alloy that can be strengthened is 38 ℃/min, so it is suitable for air-cooled quenching. The cooling intensity can be changed by changing the number of revolutions of the fan and fan, so that the temperature of the products before tension straightening can be reduced to below 60 ℃

4. Tension straightening

after the die hole of the profile, it is generally pulled by the tractor. When the tractor works, it gives the extruded products a certain traction tension and moves synchronously with the outflow speed of the products. The purpose of using the tractor is to reduce the uneven length and scratches during multi line extrusion, and also to prevent the twisting and bending of the profile after the mold hole, which will bring trouble to the tension straightening. Tension straightening can not only eliminate the longitudinal shape irregularity of the product, but also reduce its residual stress, improve its strength characteristics and maintain its good surface

5. Artificial aging of aluminum materials

aging treatment requires uniform temperature, and the temperature difference does not exceed ± ℃. The artificial aging temperature of 6063 alloy is generally 200 ℃. The aging holding time is hours. In order to improve mechanical properties, aging at ℃ for hours is also used, but at this time, the production efficiency will be reduced

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