7075 Mechanical properties of aluminum alloy applications and status
7 series aluminum alloy is Al-Zn-Mg-Cu, The alloy has been used in the aircraft manufacturing industry since the late 1940s. The 7075 aluminum alloy has a tight structure and strong corrosion resistance, which is the best for aviation and Marine plates.Ordinary corrosion resistance, good mechanical properties and anode reaction.
Fine grains make better deep drilling performance and enhanced wear resistance. The best strength of aluminum alloy is the 7075 alloy, but it can not be welded, and its corrosion resistance is quite poor, many CNC cutting manufacturing parts use the 7075 alloy. Zinc is the main alloy element in this series, plus a little magnesium alloy can enable the material to be heat-treated, to reach the very high strength characteristics.
This series of materials are generally added to a small amount of copper, chromium and other alloys, and among which the number 7075 aluminum alloy is especially the top quality, the highest strength, suitable for aircraft frame and high strength accessories.Its characteristics are, good plasticity after solid solution treatment, heat treatment reinforcement effect is particularly good, has a high strength below 150℃, and has a particularly good low temperature strength;Poor welding performance; stress corrosion cracking tendency; coated aluminum or other protective treatment. Double aging can improve the resistance of alloy stress corrosion cracking. The plasticity in the annealed and just quenched state is slightly lower than the same state of 2A12. slightly better than 7A04, plate static fatigue. Gtch is sensitive, stress corrosion is better than 7A04. density is 2.85 g/cm3.
7075 aluminum alloy has excellent mechanical properties, specific performance in the following aspects:
1. high strength: The tensile strength of 7075 aluminum alloy can reach more than 560MPa, which belongs to the high strength material of aluminum alloy, which is 2-3 times that of other aluminum alloys under the same conditions.
2. Good toughness: The section shrinkage rate and elongation rate of 7075 aluminum alloy are relatively high, and the fracture mode is toughness fracture, which is more suitable for processing and forming.
3. Good fatigue performance: 7075 Aluminum alloy can still maintain its good mechanical properties under high stress and frequent reciprocating load, without oxidation, crack and other phenomena.
4. extremely efficient in preserving heat: 7075 Aluminum alloy can still maintain its good mechanical properties in high temperature environment, which is a kind of high temperature resistant aluminum alloy.
5. Good corrosion resistance: 7075 Aluminum alloy has good corrosion resistance and can be used in the manufacture of parts with high corrosion resistance requirements.
Condition：
1.O-state: (annealed state)
Implementation method: Heat the 7075 aluminum alloy to an appropriate temperature, usually at 350-400 degrees Celsius, keep for a period of time and then slowly cool to room temperature, the purpose: to eliminate internal stress and improve the plasticity and toughness of the material.The maximum tensile strength of 7075 (7075-0 tempering) shall not exceed 280 MPa (40,000 psi) and the maximum yield strength of 140 MPa (21,000 psi). The elongation of the material (stretching before the final failure) is 9-10%.
2.T6 (aging treatment):
Implementation method: the first solid solution treatment is the alloy heating to 475-490 degrees Celsius and rapid cooling and then aging treatment, usually at 120-150 degrees Celsius insulation for several hours, the purpose: to improve the strength and hardness of the material.The ultimate tensile strength of T6 tempering 7075 is 510,540 MPa (74,00078,000 psi) with a yield strength of at least 430,480 MPa (63,00069,000 psi). It has a failure extension rate of 5-11%.
3.T651 (stretching + aging hardening):
Implementation method: on the basis of T6 aging hardening, a certain proportion of stretching to eliminate residual stress, the purpose: to maintain high strength and hardness while improving plasticity and toughness.The ultimate tensile strength of T651 tempering 7075 is of 570 MPa (83,000 psi) and a yield strength of 500 MPa (73,000 psi). It has a failure elongation rate of 3 – 9%. These attributes can be changed depending on the form of the material used. Thicker plates may exhibit lower strength and elongation than the numbers listed above.
Main use of 7075 aluminum alloy:
1.Aerospace field: 7075 aluminum alloy is widely used in the field of aerospace because of its high strength and lightweight characteristics. It is often used in the manufacture of aircraft structures, wings, bulkheads and other key components, as well as other structures that require high strength and corrosion resistance.
2. automotive industry:The 7075 aluminum alloy also plays an important role in automobile manufacturing. It is often used in the braking system and chassis parts of high-performance cars and racing cars, so as to improve the performance of vehicles and reduce the weight.
3. exercise equipment:Due to its high strength and lightweight characteristics, 7075 aluminum alloy is often used to make sports equipment, such as hiking sticks, golf clubs, etc.
4. machine building:In the field of mechanical manufacturing, 7075 aluminum alloy is also widely used in the manufacture of precision parts, molds and so on. In addition, 7075 aluminum alloy is also widely used in blowing plastic (bottle) mold, ultrasonic plastic welding mold, shoe mold, paper plastic mold, foam forming mold, wax mold, model, fixture, mechanical equipment, mold processing and other fields. It is also used to make high-end aluminum alloy bicycle frames.
It should be noted that although the 7075 aluminum alloy has many advantages, it is still necessary to pay attention to its poor welding performance and the tendency of stress corrosion cracking, so the aluminum coating or other protection treatment may be required in use.
In general, the 7075 aluminum alloy has an indispensable position in many industrial fields because of its excellent performance and wide applicability.
