Differences Between 6061 and 7075 Aluminum?

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Differences Between 6061 and 7075 Aluminum?

6061 and 7075 are both aluminum alloys with similar properties, but the difference is very large. 6061 belongs to the 6000 series aluminum alloy, while 7075 belongs to the 7000 series aluminum alloy. Today, we will analyze the difference between 6061 and 7075 for you:


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1. Composition of aluminum alloy:

First, let’s introduce the definition of alloy. The so-called “alloy” refers to two or more metals that are heated and melted to synthesize a new type of metal, while the so-called “aluminum alloy” refers to the use of aluminum alloyed with other metals to be heated and melted. , and aluminum also occupies the highest proportion in the alloy. The general way of indicating the composition of aluminum alloys is to use 4 Arabic numerals to indicate, which clearly indicates the various metal elements contained in the aluminum alloy. The first digit is the most important metal element added in the aluminum alloy, except for the aluminum element. Its representation is such as: (various aluminum alloy codes and the metal elements added to the alloy represented by them) digital.

Main alloying elements:
1XXX… Aluminum (Aluminum) is estimated to account for at least 99%
2XXX… Copper
3XXX… Manganese
4XXX… Silicon
5XXX… Magnesium (Magnesium)
6XXX…Magnesium and Silicon
7XXX… Zinc

In the number group from 2XXX to 7XXX, the second number indicates the way the alloy is processed, and the last two numbers are provided for distinguishing use within the same series of groups. Each different aluminum alloy has its applicable occasions and limitations. In the use of industrial products, the most commonly seen and the most widely used are the two specifications of 6061 and 7075. We will discuss below. Further explanation for these two:

6061aluminum alloy: In the 6061 specification aluminum alloy, aluminum alloy elements account for 97.9%, magnesium elements account for 1%, silicon elements account for 0.6%, and 0.28% copper and 0.2% chromium are added.

7075aluminum alloy: In the 7075 aluminum alloy, the main metal elements of aluminum and zinc account for 90% and 5.6%, respectively, and the other elements are magnesium 2.5%, copper 1.6%, and chromium 0.23%. Finally, there is a remainder. It is a metal element such as silicon, manganese, titanium, etc.

 Differences Between 6061 And 7075 Aluminum?

2. Basis for strength measurement of aluminum alloys, Is 6061 or 7075 stronger??

Generally, we have various methods for measuring the strength of metals, but again we propose three most commonly used methods as the basis for measuring the strength of aluminum alloys. It is yield force (Yield), shear force (Shear) and tension (Tensile) and the units of measurement are imperial (KSI: thousands of pounds per square inch) (thousands of pounds persquare inch) Compared with the metric system (KN/m: kilonewton force per square meter) and for the sake of unity, this article uses (KSI) as the unit of measurement.

The so-called “yield force” means the minimum force to break the polymer network. Every surface of an object is limited by the force it can withstand, and once this force is exceeded, the object begins to deform and lose its original shape. And if it is explained in the way we are generally more familiar with, the minimum force that an object can bear on a unit area without causing it to deform is the yield force. The shear force is used to measure the impact force that the object can withstand from the side. The most widely used part of the remote control car is the part of the swing arm latch, which is made of materials with higher shear force. The swing arm latch, the greater the side impact force it can withstand, and the less likely it is to bend and deform. The last item is the more familiar tension, which represents the minimum force required to pull the object apart, and tension is sometimes referred to as the ultimate strength or ultimate strength of the object. Here we attach the data of the strength measurement of 6061 and 7075 aluminum alloys for your reference:

Aluminum alloy: (Yield) (Shear) (Tensile)

6061: 7KSI 10KSI 13KSI

7075: 15KSI 22KSI 33KSI

Various intensity measurements for the 6061 and 7075. From the above table, we can clearly see that compared with 6061 aluminum alloy, 7075 has significantly higher measurement data in all aspects that means 7075 is much harder than 6061(7075 aluminum alloy is stronger than 6061 aluminum alloy and it is the hardest aluminum), and this is mainly because the content of aluminum alloy in 7075 aluminum alloy is higher than that of 6061 aluminum alloy. It also contains nearly 8% less aluminum (97.9% aluminum in 6061 and 90% aluminum in 7075). Because pure aluminum is a very soft metal element. The toughness of the metal (Temper) is alloyed, which can change the properties of the metal itself, making it become another material with completely different physical properties. In addition to alloys, another method that can be used to improve the overall strength of metals is what is called “heat treatment”, which is to increase the strength of the metal by rapidly cooling it after being heated at a high temperature.

3. Status analysis of 6061 and 7075:

It is generally used to describe the properties of metals after “heat treatment”, which is the so-called “toughness (Temper)”. The general way to describe the “toughness” of metals is to use different English abbreviations. Here we list the meanings of several common English letters for your reference:

F: Indicates that the metal is not subjected to special treatment after processing (including: cold working, hot working or casting).
O: Indicates that the metal is then processed by “Annealed” to the minimum required strength level. Generally, the purpose of “annealing” is to soften the work-hardened parts again and restore them to the required toughness, so as to increase the ductility and stability of the material and facilitate further processing.
W: refers to the use of “Solution Treatment” and “Natural Aging” to achieve the purpose of metal hardening. The heat treatment method is generally used in the 7XXX series of aluminum alloys to improve its hardness.
H: Indicates the finished product that has been processed and deformed. This is a way to improve the strength of the material itself without the need for additional heat treatment.

T: A heat treatment method that can strengthen the toughness of the material more than the above-mentioned “F”, “O” or “H”. Generally, after the letter “T”, it will be followed by one or more numbers. As we often hear “T6” is one of them.

The above-mentioned “solution heat treatment” and “natural aging” are both types of hardening heat treatment, and the general practical precipitation hardening heat treatment procedure usually includes three steps: solution heat treatment, quenching and Aging Treatment. The so-called “solution heat treatment” refers to the process of completely heating the material in the alloy until the metal melts, so that all the solutes are dissolved together; The process of cooling for greater hardness. The “aging treatment” places the “quenched” object at a constant temperature, so that its internal structure gradually changes, and fine precipitates are produced, resulting in changes in properties. If this constant temperature is at room temperature, it is called “natural aging”; if it is carried out in a high-temperature furnace, it is called “artificial aging”.

In all applications, we often see aluminum alloys with a “T6” heat treatment. If it is “T6061-T6” heat-treated aluminum alloy, it can even make the original 6061 material have higher “yield force” and “tension” than 7075 aluminum alloy (refer to the table below), but in terms of “clip force” , it is lower than 7075. Therefore, after the “T6” heat treatment, the “yield force” and “tension” of the aluminum alloy can be greatly improved, but the increase in the “shear force” is relatively small, while This heat treatment technology is also applicable to 6061 and 7075 materials.

Aluminum alloy code (Yield) (Shear) (Tensile)

6061:           7KSI     10KSI     13KSI
7075:         15KSI    22KSI     33KSI
6061—T6:  31KSI    17KSI     35KSI
7075–T6:   73KSI   48KSI     83KSI

Above: Various strength measures obtained after heat treatment with “T6” grade.

4. Learn more about 7075-T6

In the above, we have explained the various strength measurement data obtained by using “T6” grade heat treatment for 6061 aluminum alloy material, and for 7075 with “T6” grade heat treatment, what kind of amazing performance will there be Woolen cloth? As shown in Table 3 above, for 7075-T6, the “yield force” is increased to nearly five times that before heat treatment (15KSI→73KSI), and the “tension” is also increased by about two and a half times (33KSI→83KSI), and the second is more surprising in terms of “shear force”. For the 6061-T6, it only increased by 7KSI (10KSI→17KSI), which is 70% of the original; on the 7075-T6, it was increased from 22KSI to 48KSI, which was more than doubled.

5. 6061, 7075 material cost difference:

The sales volume and utilization rate of 6061 in the market are much higher than those of 7075. 6061 is the aluminum alloy material with the highest sales volume among the aluminum alloys. Because its performance is basically in line with various industrial uses such as aluminum machining and equipment processing, it has become a household name. The brand has won unanimous praise from the majority of manufacturers in the traditional use, so it is a habit to choose 6061 as the raw material. There are also factories with relatively low production and processing costs for 6061, so the supply and usage of 6061 are relatively huge. Generally, the price of 6061 is 4 dollars per kilogram, while the price of 7075 is 7 dollars per kilogram. Therefore, 6061 is generally selected instead of 7075, because the price of 7075 is relatively high, and it is generally an aluminum alloy material for aerospace industrial.

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Author: Mose Li

Author: Mose Li

Director of Project Engineering at 3Q Machining


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