Aluminum 6063

What Is Aluminum 6063

6063 aluminum is widely used in the framework of building aluminum doors, windows and curtain walls. In order to ensure that doors, windows and curtain walls have high wind pressure resistance, assembly performance, corrosion resistance and decoration performance, the requirements for the comprehensive performance of aluminum alloy profiles are much higher than those in industry Profile standards.

Within the composition range of 6063 aluminum material specified in the national standard GB/T3190, different values of the chemical composition will result in different material characteristics. When the chemical composition has a large range, the performance difference will fluctuate in a large range. , So that the comprehensive performance of the profile will be out of control.
The chemical composition of 6063 aluminum has become the most important part of the production of high-quality aluminum alloy building profiles.

7009 aluminum alloy, American deformed aluminum and aluminum alloy. Aluminum alloys are divided into two categories: cast aluminum alloys, which are used in the as-cast state; deformed aluminum alloys, which can withstand pressure processing and have higher mechanical properties than the as-cast state. It can be processed into various shapes and specifications of aluminum alloy materials. Mainly used in the manufacture of aviation equipment, daily necessities, construction doors and windows, etc.

6063 is a representative alloy for extrusion. Its strength is lower than that of 6061. It has good extrudability and can be used as a shape with complex cross-sections. It has good corrosion resistance and surface treatment.

It is a low-alloyed Al-Mg-Si series high plastic alloy. Has many valuable features:

•  – Strengthened by heat treatment, high impact toughness, insensitive to imperfections.
•  – With good thermoplasticity, it can be extruded at high speed into complex, thin-walled, hollow profiles or forgings with complex structures. The quenching temperature range is wide, and the quenching sensitivity is low. After extrusion and forging demoulding, as long as The temperature is higher than the quenching temperature. It can be quenched by spraying or penetrating water. Thin-walled parts (6 less than 3mm) can also be wind quenched.
•  – Excellent welding performance and corrosion resistance, no stress corrosion cracking tendency. Among the heat-treatable aluminum alloys, the Al-Mg-Si series alloy is an alloy in which no stress corrosion cracking phenomenon has been found in 6063.
• – After processing, the surface is very smooth and easy to anodize and color. The disadvantage is that if it is left at room temperature for a period of time after quenching, the strength will be adversely affected (parking effect).

The Application Range And Purpose

Within the composition range of 6063 aluminum alloy specified in the national standard GB/T3190, different values ​​of the chemical composition will result in different material characteristics. When the chemical composition has a large range, the performance difference will fluctuate in a large range. , So that the comprehensive performance of the profile will not be controlled. Therefore, it is preferable that the chemical composition of 6063 aluminum alloy becomes the most important part of the production of high-quality aluminum alloy building profiles. The role of alloying elements and its effect on performance 6063 aluminum alloy is a medium-strength heat-treatable strengthening alloy in the AL-Mg-Si series. Mg and Si are the main alloying elements. The main task of optimizing the chemical composition is to determine the Mg and Si Percentage content

• The application of strip is widely used in decoration, packaging, construction, transportation, electronics, aviation, aerospace, weapons and other industries.
• Aerospace aluminum is used to make aircraft skins, fuselage frames, girders, rotors, propellers, fuel tanks, siding and landing gear pillars, as well as rocket forging rings, spacecraft siding, etc.
• Aluminium materials for transportation are used in the body structure materials of automobiles, subway cars, railway passenger cars, high-speed passenger cars, doors and windows, shelves, automobile engine parts, air conditioners, radiators, body panels, wheels and naval materials.
• Aluminum materials for packaging 　 All-aluminum easy-open cans are mainly used as metal packaging materials in the form of thin plates and foils to make cans, lids, bottles, barrels, and packaging foils. It is widely used in the packaging of beverages, food, cosmetics, medicines, cigarettes, and industrial products.
• Aluminum materials for printing are mainly used to make PS plates, and aluminum-based PS plates are a new type of material in the printing industry for automated plate making and printing.
• Aluminum alloy for building decoration because of its good corrosion resistance, sufficient strength, excellent process performance and welding performance, through the introduction of many experts from Dongguan Dingli Metal Materials Co., Ltd., it is mainly widely used in building frames, doors and windows, Ceiling, decorative surface, etc. Such as various architectural doors and windows, aluminum profiles for curtain walls, aluminum curtain wall panels, profiled panels, checkered panels, color coated aluminum panels, etc.
• Aluminum materials for electronic appliances are mainly used in various fields such as bus bars, overhead wires, conductors, electrical components, refrigerators, air conditioners, and cables.
• Specification: round rod, square rod

Representative uses include aerospace fixtures, electrical fixtures, communications, and are also widely used in automated mechanical parts, precision machining, mold manufacturing, electronics and precision instruments, SMT, PC board solder carriers, and so on.

The Chemical Composition Of Aluminum 6063

• Aluminum Al: margin
• Silicon Si: 0.20～0.60
• Copper Cu: 0.10
• Magnesium: 0.45～0.9
• Zinc Zn: 0.10
• Manganese Mn: 0.10
• Titanium Ti: 0.10
• Chromium Cr: 0.10
• Iron Fe: 0.35

The Control Range Of Aluminum 6063

• 3.1 The control range of Mg Mg is a flammable metal, which will be burnt during smelting operation. When determining the control range of Mg, the error caused by burning should be considered, but it should not be too wide to prevent the alloy performance from getting out of control. Based on experience and the level of our factory’s ingredients, smelting and laboratory tests, we have controlled the fluctuation range of Mg within 0.04%, the T5 profile is 0.47% to 0.50%, and the T6 profile is 0.57% to 0.50%. 60%.
• 3.2 The control range of Si When the range of Mg is determined, the control range of Si can be determined by the ratio of Mg/Si. Because the factory controls Si from 0.09% to 0.13%, Mg/Si should be controlled between 1.18 and 1.32.
• 3. The selection range of the chemical composition of the 36063 aluminum alloy T5 and T6 state profiles. If you want to change the alloy composition, for example, if you want to increase the amount of Mg2Si to 0.95%, so as to facilitate the production of T6 profiles, you can move Mg up to a position of about 0.6% along the upper and lower limits of Si. At this time, Si is about 0.46%, Si is 0.11%, and Mg/Si is 1.
• 3.4 Concluding remarks According to our factory’s experience, the amount of Mg2Si in 6063 aluminum alloy profiles is controlled within the range of 0.75% to 0.80%, which can fully meet the requirements of mechanical properties. In the case of a normal extrusion coefficient (greater than or equal to 30), the tensile strength of the profile is in the range of 200-240 MPa. However, controlling the alloy in this way not only has good plasticity, easy extrusion, high corrosion resistance and good surface treatment performance, but also saves alloying elements. However, special attention should be paid to strictly control the impurity Fe. If the Fe content is too high, the extrusion force will increase, the surface quality of the extruded material will deteriorate, the anodic oxidation color difference will increase, the color will be dark and dull, and Fe will also reduce the plasticity and corrosion resistance of the alloy. Practice has proved that it is ideal to control the Fe content within the range of 0.15% to 0.25%.

Ingredient Optimization

6063-T5 architectural aluminum profiles must have certain mechanical properties. When other conditions are the same, its tensile strength and yield strength increase with the increase of content. The strengthening phase of 6063 Taijin is mainly the Mg2Si phase. How much should the amount of Mg, Si and Mg2Si be? The Mg2Si phase is composed of two magnesium atoms and one silicon atom. The relative atomic mass of magnesium is 24.3l and the relative atomic mass of silicon is 28.09. Therefore, the mass ratio of magnesium to silicon in the Mg2Si compound is 1.73: 1.

Therefore, according to the above analysis results, if the ratio of magnesium to silicon content is greater than 1.73, there is excess magnesium in the alloy in addition to the formation of Mg2Si phase. On the contrary, the ratio is less than 1.73, indicating that silicon in addition to the formation of Mg2Si phase, also There is surplus silicon.

Excess magnesium is harmful to the mechanical properties of the alloy. Magnesium is generally controlled at about 0.5%, and the total amount of Mg2Si is controlled at 0.79%. When the silicon surplus is 0.01%, the mechanical properties σb of the alloy is about 218Mpa, which has greatly exceeded the national standard performance, and the surplus silicon increases from 0.01% to 0.13%, and the σb can be increased to 250Mpa, that is, an increase of 14.6. %. To form a certain amount of Mg2Si, the silicon loss caused by the impurities such as Fe and Mn must be considered first, that is, a certain amount of excess silicon must be ensured. In order to make the magnesium in the 6063 alloy fully match the silicon, in the actual batching, Mg:Si<1.73 must be consciously made. The surplus of magnesium not only weakens the strengthening effect, but also increases the cost of the product.

Therefore, the composition of 6063 alloy is generally controlled as follows: Mg: 0.45%-0.65%; Si: 0.35%-0.50%; Mg: Si = 1.25-1.30; the impurity Fe is controlled within <0.10%-0.25%; Mn<0.10%.

The Annealing Process Of Aluminum 6063

In the production of civil extruded profiles, the high temperature homogenization annealing specification of 6063 alloy is: 560±20℃, heat preservation 4-6h, and the cooling method is forced air cooling or water spray cooling.

The homogenization treatment of the alloy can increase the extrusion speed. Compared with the ingot without homogenization treatment, the extrusion force can be reduced by about 6%-10%. The cooling rate after homogenization has an important influence on the precipitation behavior of the structure. For ingots that are rapidly cooled after soaking, almost all Mg2Si can be dissolved in the matrix, and the excess Si will also be dissolved or dispersed as fine particles. Such an ingot can be quickly extruded at a lower temperature, and obtain excellent mechanical properties and surface brightness.

In the aluminum extrusion production, replacing the resistance heating furnace with oil or gas heating furnaces can achieve significant energy saving and consumption reduction effects. Reasonable selection of furnace type, burner and air circulation mode can make the furnace obtain uniform and stable heating performance, and achieve the purpose of stabilizing the process and improving product quality.

After several years of operation and continuous improvement of the combustion type ingot heating furnace, furnace models with a combustion efficiency higher than 40% have been introduced on the market. After the ingot is loaded into the furnace, the temperature rises rapidly to above 570℃, and after a period of holding time, it is discharged and extruded when the discharge zone is cooled to close to the extrusion temperature. The ingot undergoes a semi-homogenization process in the heating furnace. This process is called The semi-homogeneous treatment basically meets the requirements of the 6063 alloy hot extrusion process, which can save a separate homogenization process, which can greatly save equipment investment and energy consumption. It is a process worth promoting.

Extrusion And Heat Treatment

3.1 Ingot heating

For extrusion production, extrusion temperature is the most basic and most critical process factor. Extrusion temperature has a great influence on product quality, production efficiency, die life, energy consumption, etc.

The most important problem of extrusion is the control of the metal temperature. From the heating of the ingot to the quenching of the extruded profile, it is necessary to ensure that the soluble phase structure does not precipitate from the solid solution or exhibits the dispersion of small particles.
The heating temperature of 6063 alloy ingots is generally set within the temperature range of Mg2Si precipitation. The heating time has an important influence on the precipitation of Mg2Si, and rapid heating can greatly reduce the possible precipitation time. Generally speaking, the heating temperature of 6063 alloy ingot can be set as:

Unhomogenized ingot: 460-520℃; Homogenized ingot: 430-480℃.

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 of the deformation zone gradually increases, and it increases with the increase of the extrusion speed. Therefore, in order to prevent extrusion cracks, as the extrusion process progresses and the temperature of the deformation zone increases, the extrusion speed should be gradually reduced.

3.2 Extrusion speed

During the extrusion process, the extrusion speed must be carefully controlled. The extrusion speed has an important influence on the thermal effect of deformation, the uniformity of deformation, the process of recrystallization and solid solution, the mechanical properties of the product and the surface quality of the product.

Extrusion speed is too fast, there will be pitting, cracks and other tendencies on the surface of the product. At the same time, the extrusion speed is too fast to increase the unevenness of the metal deformation. The flow rate during extrusion depends on the alloy type and the geometry, size and surface condition of the profile.

6063 alloy profile extrusion speed (metal outflow speed) can be selected from 20-100 m/min.

With the advancement of modern technology, the extrusion speed can be controlled by program or simulation 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 of the deformation zone within a certain 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 induction heating is used, there is a temperature gradient of 40-60°C (gradient heating) along the length of the ingot. During extrusion, the high temperature end faces the extrusion die and the low temperature end faces the extrusion pad to balance a part of the deformation heat; Water-cooled die extrusion, that is, forced cooling by passing water at the back end of the die, the test proves that the extrusion speed can be increased by 30%-50%.

In recent years, nitrogen or liquid nitrogen is used to cool the mold (extrusion mold) abroad to increase the extrusion speed, increase the life of the mold and improve the surface quality of the profile. In the extrusion process, the nitrogen is introduced to the exit of the extrusion die, which can make the cooled product shrink rapidly, cool the extrusion die and the metal in the deformation zone, so that the deformation heat is taken away, and at the same time, the exit of the mold is affected by the nitrogen atmosphere. Control, reduce the oxidation of aluminum, reduce the adhesion and accumulation of aluminum oxide, so the cooling of nitrogen improves the surface quality of the product, which can greatly increase the extrusion speed. CADEX is a newly developed extrusion process. The extrusion temperature, extrusion speed and extrusion force in the extrusion process form a closed loop system to maximize the extrusion speed and production efficiency while ensuring the best Performance.

3.3 Quenching on the machine

6063-T5 quenching is to remove the Mg2Si solid-dissolved in the base metal at a high temperature and then quickly cool it to room temperature and be retained. The cooling rate is often proportional to the strengthening phase content. The minimum cooling rate that the 6063 alloy can be strengthened is 38°C/min, so it is suitable for air-cooled quenching. Changing the number of fan and fan revolutions can change the cooling intensity and reduce the temperature of the product before tension straightening to below 60°C.

3.4 Tension straightening

After the profile is out of the mold hole, it is generally pulled by a tractor. When the traction machine is working, it applies a certain traction tension to the extruded product and moves synchronously with the product outflow speed. The purpose of using the tractor is to reduce the uneven length and scratches during multi-line extrusion, and also to prevent the profile from twisting and bending after exiting the die hole, which brings trouble to tension straightening.

Tension straightening can not only eliminate the longitudinal shape irregularity of the product, but also reduce its residual stress, improve the strength characteristics and maintain its good surface.

3.5 Artificial aging

Aging treatment requires uniform temperature, and the temperature difference does not exceed ±3-5℃. The artificial aging temperature of 6063 alloy is generally 200℃. The aging holding time is 1-2 hours. In order to improve the mechanical properties, aging at 180-190℃ is also used for 3-4 hours, but the production efficiency will be reduced at this time.