Aluminum alloys are among the most versatile and effective materials for developing products for use in various industries. This material has excellent strength, excellent corrosion resistance, heat treatability, good weldability and formability. For this reason, many manufacturers use different types of aluminum alloys in different applications.
Aluminum is available in different grades, each with different alloying elements and properties. Therefore, you need to know the differences between these aluminum alloy grades to choose the most suitable one for your project. This guide examines the types of aluminum alloys, their properties, benefits and applications.
What is aluminum alloy?
Aluminum alloy is a unique combination of several metallic elements with greater strength and durability. Aluminum is traditionally light and has excellent corrosion resistance. These alloys are created by combining aluminum in liquid/molten form with other elements, which subsequently cools and solidifies to form a homogeneous solid material. The other elements that combine with aluminum to form these alloys can represent up to 15% of the total mass.
Examples of these additional elements include zinc, iron, magnesium, copper and silicon. Most importantly, the addition of these elements to aluminum gives the alloy better electrical conductivity, corrosion resistance, workability and strength than pure metal elements.
Aluminum Properties
Aluminum has many excellent properties that make it famous and widely used in most applications. Here are some of them:
Corrosion resistance
Aluminum forms a thin natural layer of oxide that protects the metal from environmental reactions. Therefore, it is suitable for various applications where it may be exposed to corrosive influences, such as: B. in vehicles. However, you should note that aluminum alloys have greater corrosion resistance than pure aluminum.
Light
The standard weight of aluminum is exactly 2.7 g/cm³, about a third of the weight of steel. Its light weight helps significantly reduce manufacturing costs. Typically, aluminum is used in automobiles to reduce weight and increase load capacity. Additionally, you can adjust the composition of aluminum alloy types to change the weight depending on the application.
Electrical and thermal conductivity
Due to its weight, aluminum is an excellent conductor of electricity and heat. Its electrical and thermal conductivity is twice that of copper. Therefore, it is often used for the construction of power transmission lines. It also acts as an excellent heat sink/distributor, making it an ideal choice for devices that require fast and rapid heat dissipation.
Applications of aluminum alloys
Here are some of the most common uses for aluminum alloys.
aerospace industry
The aircraft industry generally requires light and strong aluminum alloys. These alloys should have an excellent strength-to-weight ratio while also fitting perfectly within the budget range. Additionally, the use of aluminum grades in aircraft helps prevent premature damage to the aircraft due to unfavorable environmental conditions.
healthcare sector
Aluminum products have helped the healthcare industry maintain its high level of cleanliness and biocompatibility. Various medical instruments, such as surgical and orthopedic, are made from different types of aluminum. Manufacturers also make other general-purpose devices, such as aluminum trays and containers.
Auto Industry
Vehicle manufacturers use aluminum grades to make ideal vehicles that are light, environmentally friendly and durable. Manufacturers use various die-cast aluminum parts in cars to make them maneuverable and robust due to the high durability and lightweight properties of aluminum alloys.
Electrical and electronic engineering
Consumer electronics manufacturers continually use various types of aluminum alloys in manufacturing products due to their high thermal conductivity. Manufacturers take advantage of aluminum's excellent thermal conductivity when producing components such as graphics processor cooling components and heat sinks.
How do you recognize aluminum alloy grades?
Generally, you can identify aluminum alloy using a 4-digit identification template. Each number on the aluminum classification chart represents a different aspect of the alloyed metal and is usually written before the pure metal element for clarity. Example: aluminum 5052.
The numbers represent separate units, such as steel alloy, titanium alloy, or other alloys. Here is a breakdown of the main alloying element that each first digit represents:
- “1” means there are no alloying elements and it is pure aluminum.
- “2” means copper
- “5” means magnesium
- “6” means magnesium and silicon
- “7” means zinc
- “8” is reserved for all other alloy components
Note that these numbers can identify the entire list of aluminum alloys. For example, if “2” represents copper, all aluminum-copper alloys are referred to as “2xxx series”.
Additionally, the second digit indicates whether the league has special league conditions and whether it has been changed from its original state. However, the digit remains “0” if there are no special changes. The third and fourth digits are typically used to serialize and differentiate individual leagues.
A 1xxx series (pure aluminum containing exactly 99% aluminum), where the last two digits indicate the minimum aluminum content above 99%. For example, 1060 aluminum contains at least 99.60% pure aluminum.
Different grades of aluminum alloys
Seven different base alloys in the range 1xxx to 7xxx are available for industrial use. Each with a unique numerical combination and different proportions and pairs. Here is the list of standard aluminum alloys for industrial use:
Series 1xxx
This class of alloys is called the pure aluminum series because it consists of 99% or more pure aluminum. These alloys offer a tensile strength of exactly 10 to 27 ksi. They are generally weldable but not heat treatable as they are susceptible to high temperatures.
These alloys have excellent electrical and thermal conductivity. Furthermore, their excellent corrosion resistance makes them ideal for manufacturing chemical tanks and pipelines.
Series 2xxx
Copper is the main alloying element in the 2xxx series, with significant amounts of magnesium, manganese, silicon and other elements. Copper, the main alloying element of the 2xxx series aluminum type, has a tensile strength of 27 to 62 ksi. These grades are highly machinable and maintain high strength over a wide temperature range, making them suitable for the aerospace industry.
Although 2xxx series alloys are strong and tough, they have lower corrosion resistance than other types of aluminum alloys. Therefore, you may consider coating or painting these aluminum alloys to improve their service life.
Series 3xxx
The 3xxx series aluminum grade contains magnesium and manganese as the main alloying element. It gives aluminum excellent mechanical resistance, which it maintains over a wider temperature range than pure aluminum.
These types of aluminum are typically not heat treatable and have tensile strengths ranging from 16 to 41 ksi. Alloy 3004 is an excellent example of an alloy suitable for packaging consumer products in this class.
4xxx series
The 4xxx series aluminum grade is the only category that includes heat treatable and non-heat treatable aluminum alloys. When silicon is added to aluminum as a primary alloying element, it lowers the melting points and improves the fluidity of the 4xxx series alloys in their molten/liquid form. Although silicon is not inherently heat treatable, some silicon alloys contain copper or magnesium, which makes them respond positively to heat treatment.
5xxx series
The 5xxx series has magnesium as the main alloying element. These aluminum alloys are typically very strong, highly resistant to corrosion and alkali, perfect for marine applications and can be welded easily. Due to their high formability, they can be easily punched, bent, rolled, stretched and twisted.
5083 aluminum is an excellent example of a 5xxx series aluminum grade that is widely used for industrial applications due to its resistance to seawater and various industrial chemicals.
6xxx series
6xxx alloys consist of magnesium and silicon, which form magnesium silicide. These aluminum alloys are easily moldable, weldable and heat treatable. Alloy 6061 is the most common aluminum alloy in the 6xxx series and has excellent corrosion resistance and good strength. Therefore, it is often used to make boat and truck structures.
Cast vs. Cast Alloys forged alloys: What are the differences?
Cast alloys and wrought alloys are the main categories of aluminum alloys. There are several significant differences between cast and forged aluminum alloys.
metal alloy elements
Wrought alloys contain fewer other metals than cast alloys. In general, wrought alloys contain ≤4% alloying elements compared to >22% for cast alloys. Although this difference may seem intangible, it has a greater impact on the material properties of these alloys.
The ductility of an aluminum alloy decreases when other alloying elements are added. This makes most cast alloys susceptible to brittle fracture. On the other hand, you can increase the strength, corrosion resistance and conductivity of wrought aluminum alloys by adding various alloying elements while maintaining their flexibility and other positive properties.
Manufacturing techniques
However, the biggest difference between these two categories is in the manufacturing technology that these alloys go through before creating the final product. Cast alloys generally leave your mold in the precise and desired solid shape.
Wrought alloys, on the other hand, require several changes to the solid form. Therefore, differences in manufacturing often have a significant impact on the possible shapes and physical properties of final products.
Characteristics
Cast aluminum alloys have lower melting points and lower tensile strength than wrought aluminum. Aluminum-silicon is the most commonly used aluminum alloy because its high silicon concentration makes casting easier. Forged aluminum is most commonly used, and manufacturers produce products through aluminum extrusion or rolling.
Types of aluminum alloy commonly used for machining
This section explains the different types of aluminum alloys you can use to machine your products.
Aluminum 6061
6061 aluminum has silicon and magnesium as its main components. Its strength, corrosion resistance, weldability and heat treatability make it suitable for various applications. It adapts well to extrusion technology and the application of T6 tempering helps to make it stronger and more durable. Likewise, it can be well anodized to obtain an improved aesthetic finish.
Aluminum 7075
7075 aluminum alloy is a strong alloy with excellent strength, similar to steel. Its most important alloying elements are copper and zinc. It is used in applications that require excellent strength, such as spacecraft, aircraft, etc. Although it is not weldable, it is strong, moderately weldable and resistant to stress.
Aluminum 5052
5052 aluminum is a reliable alloy with excellent corrosion resistance and moderate strength. It is ideal for saltwater applications because the alloy does not contain copper. Marine equipment is the most common part made from 5052 aluminum. However, 5052 belongs to the 5xxx aluminum alloy class and therefore cannot be heat treated.
Aluminum 6063
6063 aluminum alloy is composed of magnesium and silicon and is often called architectural aluminum because of its moderate strength and high ductility. It is very compatible with molding. Additionally, 6063 aluminum is highly resistant to corrosion due to its magnesium silicide composition.
Common parts made from 6063 aluminum include architectural products, furniture, pipes, etc. Laser engraved aluminum is also compatible with this type of aluminum.
Considerations for Choosing the Right Type of Aluminum Alloy
Choosing the appropriate type of aluminum for your project is critical to achieving ideal results. Here are the most important factors you should consider before choosing an aluminum alloy.
1. Assess machinability
The machinability rating of an aluminum alloy indicates the material's compatibility with CNC aluminum machining processes. It is helpful to know that 6061-T6 aluminum, 2011 aluminum, and 7075 aluminum are suitable alloys with high to moderate machinability ratings. Therefore, you can use these materials to produce complex parts with complicated requirements.
2. Costs and availability of materials
When choosing a material for your project, it is important to consider the cost of the aluminum alloy. Find a balance between your budget and material cost with the ideal properties for your project. This way you create an efficient basis for your production process.
Additionally, the prices of the selected aluminum grade determine the availability of the aluminum alloy. A scarce type of aluminum slows down the manufacturing process. For example, 7075 aluminum offers excellent machinability but is extremely expensive. On the other hand, 6061 aluminum is much cheaper and has lower hardness and tensile strength, making machining easier.
3. Heat treatment
Heat treating involves treating aluminum alloys at extreme temperatures to improve their strength and durability. Therefore, you must find out which aluminum series are heat treatable and which are not.
However, it is useful to know that 2xxx, 6xxx and 7xxx series aluminum alloys are heat treatable. You can heat treat parts made from these alloys to improve the strength of the finished products.
Get aluminum machining solutions at WayKen
Concluding
Aluminum is a commonly used metallic material with versatile properties that depend on elemental composition. Various types of aluminum alloys have different properties, making them suitable for different applications. Therefore, it is important to understand the differences between these aluminum alloys to choose the ideal material for your projects.
Common questions
Do aluminum alloys rust?
The quality of all metal materials deteriorates over time if not properly cared for. Although aluminum does not rust, there is a high chance of corrosion. However, the aluminum oxide layer on the surface protects the material from corrosion.
Which aluminum alloy between 6061 and 7075 is easiest to machine?
6061 aluminum alloy has several advantages compared to 7075 aluminum when considering the manufacturing process. This is because 6061 has lower hardness and tensile strength and is therefore easier to machine than 7075.
