Properties & Selection of Alloy for Extrusion of Aluminum Profile

The 6XXX series alloys are the most popular alloys used to make aluminium profiles. All of them have medium strength, but it is possible to increase it by heat treatment. 

The most popular, frequently used and affordable alloys in this series include: 

• 6061 aluminium– Durable, heat- conductive, easy to handle; 
• 6063  aluminium- Has a smooth surface, easy to process, suitable for use in structures that do not require high strength;
• 6082 aluminium – of all the presented alloys, has the highest compressibility, has high strength after heat hardening, high corrosion resistance; 
• 6005 aluminium – high strength, suitable for use of thin-walled hollow sections.

These are the most popular models, which have the following number of advantages- corrosion resistance, high weldability, easy formability during forging and other operations. These are models that are used for profiles in the automotive industry, in the construction of houses, ships and in many other areas of human life. 

General Characteristics of Alloys

The main properties of alloys of this series depend on the chemical composition and the dominant influence of magnesium and silicon. These are the main components of the alloy that affect the compressibility index. Copper in alloys of this series has a minimal effect on the compressibility, but it affects the strength characteristics and reflective properties of the coating. 

During heat treatment, the strength of 6XXX alloys can be increased to 250 N/mm2 including 6061 aluminium alloy, while maintaining their ductility up to 12%. These types of allies are designed to create various types of profiles, they can also be used for rolling sheets. They are used in welded and bolted and riveted structures. 

Comparison of Alloys – Their Similarities And Differences

The alloys listed above have three main indicators; tensile strength, yield strength and elongation. The choice of the alloy is necessary depending on its application. 

6061 aluminium alloy can be used for the same purposes as the previous one but has a slightly lower strength and fluidity. The minimum indicators are 260 in strength and 240 in yield strength, but the elongation coefficient is one percent higher and is 8%. Aluminium alloy 6005 has a high percentage of aluminium capacity, from 97.5 to 99%. Although 6061 has fairly high strength properties, it compresses relatively poorly compared to 6005 and even the tougher 6082.

In comparison, alloy 6061 can withstand pressures up to 45,000 psi. But these data were obtained in laboratory conditions using pipes made of different aluminium alloys as an example. In finished frames, additional factors such as weld quality, pipe shape and wall thickness affect the load resistance.

From the presented alloys, most of the profiles are made all over the world. Almost 75% of the total number of profiles produced is made of 6063 alloys, and only 25% of all the others.

Of the alloys presented, the highest compressibility is in 6063, the analogue of which is AD 31. The minimum tensile strength of this alloy is 205 MPa, the yield point is 170 MPa, and the elongation is 8%. 

Due to the increased content of magnesium in the composition, it can be used in lightly loaded building structures. Alloy AD31 in the USSR was determined by GOST 4784-97, and until 2000 had 100% similarity with 6063. Now, this alloy has large tolerances for impurities, especially for iron, the capacity of which has increased from 0.35 to 0.5.

Alloy 6082 corresponds to the analogue of AD35 and has the highest strength indicators, therefore it is suitable for use in building structures such as facades, windows and doors. It has the following characteristics: the minimum tensile strength is 310 MPa, the yield point is 270 MPa, and the elongation rate is 7%.