Aluminum is used in various industrial products, including aircraft, home appliances, and auto parts. Generally, aluminum is lighter than iron-based materials, but its disadvantage is lower strength. However, aluminum A7075 is one of the strongest aluminum alloys, and its strength is comparable to iron-based metal materials. This article will introduce the uses, advantages, and disadvantages of A7075, and its differences from other aluminum materials.
What is Aluminum A7075?
A7075 refers to an aluminum alloy material called “super duralumin alloy” in the “JIS H 4040” standard. This is an AL-ZN-MG-CU-type alloy containing zinc, magnesium, and copper. The 7000 series is roughly divided into AL-ZN-MG-CU type and AL-ZN-MG type. A7075 is the representative material of the AL-ZN-MG-CU type. The aluminum alloy 7000 series also includes A7072 and A7N01. A7075 can significantly increase its strength through heat treatment (T6 treatment), a typical heat treatment method for aluminum alloys.
Its strength can be improved by solution treatment, quenching, and age hardening. Solution treatment involves heating the metal to a solid solution state, dissolving the elements in it, and then quenching it. Age hardening is a method of maintaining a solution-treated material at the appropriate temperature to increase its strength. Aluminum A7075 is strong and lightweight, just like regular aluminum. Therefore, it is suitable for products that require high strength but lightweight. In the past, it was also used in fighter jets of the Japanese Navy.
Features of Aluminum A7075
The following describes the characteristics of A7075 from two aspects: advantages and disadvantages.
Advantages of A7075
High strength: The biggest feature of A7075 is its high strength. It is the strongest among all aluminum alloys, with a tensile strength of approximately 570N/MM^2. Its hardness is also very high, about 150HBW. Due to its higher strength, it can be used in parts that are subject to high loads and impacts. It can also be used on parts that are easily scratched by friction.
Good machinability: A7075 has a cutting index of 120, making it relatively easy to machine. Although it is slightly inferior to the general-purpose aluminum alloy A5052 with a cutting index of 180, compared to stainless steel, which has a cutting index of about 55, A7075 can be said to be an easy-to-cut material.
Disadvantages of A7075
Corrosion resistance: Pure aluminum is a highly corrosion-resistant material because it combines with oxygen to form an aluminum oxide film (oxide film) on its surface. However, because A7075 contains copper, it is prone to intergranular corrosion and cannot form a stable oxide film on the surface. Therefore, its corrosion resistance is not as good as other aluminum alloys.
Weldability: When Aluminum A7075 is welded, a phenomenon called solidification cracks sometimes occurs. Solidification cracks refer to the phenomenon that shrinkage strains occur when the heated and melted liquid phase completes solidification, leading to cracks. Although it is not impossible to weld, the weldability of stainless steel, iron, A5052, etc. is higher than that of A7075.
The strength will decrease with long-term use: the tensile strength of A7075 is about 270N/MM^2 without heat treatment, but after T6 treatment, it can be increased to about 570N/MM^2. This is a very high strength value, but age hardening of the T6 treatment has the disadvantage that the strength gradually decreases after long-term use.
Higher cost: Although A7075 has higher performance, it is more expensive than other aluminum alloy materials. It is generally recommended to use A7075 in parts that require strength and use general-purpose aluminum alloys such as A5052 in other parts.
Applications of Aluminum A7075
A7075 has a wide range of applications due to its lightweight and high strength. Its main uses are introduced below.
- Aerospace Related: Due to its lightweight and high strength, Aluminum A7075 is often used as a component material for aircraft, satellites, rockets, etc. For example, it is used in many housings and high-precision ring parts.
- Vehicles and Robots Related: Vehicle-related parts such as railways and automobiles can also use Aluminum A7075. It can also be used for structural parts of robots that require strength.
- Metal Mold: Because of its high strength and resistance to wear, metal molds can be used for injection molded products.
- Sports Equipment: Used for sports equipment such as skis and metal ball boards. Because of its lightweight and strong impact resistance, it is suitable for use in competitive sporting goods.
Differences Between A7075 and other Metal Materials
Aluminum alloys range from 1000 series to 8000 series, each with its own characteristics. This article will introduce the differences between A7075 and the commonly used aluminum alloys A2017, A2024 and A5052. In addition, the differences between stainless steel, iron, and Aluminum A7075 are also introduced.
The Difference between Duraluminum Alloy and Superduraluminum Alloy
There are three kinds of aluminum called duralumin alloy, A2017 is called duralumin alloy, A2024 is called super duralumin alloy, and A7075 is called super duralumin alloy. A2017 contains copper and magnesium and has excellent strength. It has the same high strength as steel materials and can be used in aircraft parts, etc. Although they both belong to the 2000 series, A2024 has higher copper and magnesium content than A2017, and its strength and machinability are better. However, A2024 has slightly worse corrosion resistance than A2017. A7075 mainly contains magnesium, zinc, and copper, and is stronger than A2017 and A2024. On the other hand, it has the potential to develop stress corrosion cracking.
Differences from A5052
A5052 belongs to the 5000 series of aluminum alloys and contains magnesium. It is the most common aluminum alloy and is also known as general aluminum. It can be used to manufacture various machinery, ships and automobile parts, etc. A5052 is characterized by its light weight and good processability. But not too strong.
Duralumin alloys, on the other hand, have their strength increased by adding copper. A7075 is not only the strongest aluminum alloy among all duralumin alloys compared to A5052. A5052 is a general-purpose aluminum material that can be used as a material for a variety of parts. A7075 is characterized by its high strength and can be used as a component material that can withstand load or impact loads. However, A7075 has poor corrosion resistance and requires full attention to the usage environment.
Differences Between Stainless Steel and Iron
The specific gravity of ordinary aluminum is generally less than half that of stainless steel and iron. Therefore, it can be used to reduce the weight of iron parts. But its strength is generally not as strong as stainless steel and iron. The specific gravity of A7075 is almost the same as ordinary aluminum, but its strength is equivalent to or higher than iron and stainless steel.
Therefore, the Aluminum A7075 is most suitable for components that are lightweight and high-strength. A7075 has poor weldability and cannot be simply welded like iron and stainless steel. Care should be taken to use screws, bolts, rivets, and other connection methods.
In Conclusion
The most notable feature of Aluminum A7075 is its high strength. It is as strong as iron or stainless steel, and like other aluminum materials, it is lightweight. It is an ideal material to choose when you want to reduce weight or increase strength compared to other aluminum materials.
However, because A7075 has poor weldability, it is necessary to pay attention to the connection relationship with other parts. When switching from the original aluminum material to Aluminum A7075, it is recommended to conduct trial production and verification.
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