Aluminum, as one of the most popular materials in CNC machining, can be manufactured into various types of components. When faced with the choice between 6061 aluminum and 7075 aluminum, many engineers often blindly pursue high strength and ignore machinability or corrosion resistance, or choose the wrong material to save money, resulting in part failure. This article will focus on the difference between 6061 and 7075. I believe that after reading this, you can choose the most suitable grade for your project within 5 minutes.
What Is 6061 Aluminum?
6061 aluminum is currently the most widely used and common extruded and machined aluminum material. This material is often the default choice for many CNC projects. 6061 aluminum belongs to the 6xxx series, which is a magnesium-silicon alloy with a magnesium content of about 1% magnesium and about 0.6% silicon. It can be said that 6061 Aluminum has achieved a good balance between various performances.
What Is 7075 Aluminum?
7075 aluminum is a zinc-magnesium-copper aluminum alloy, belonging to the zinc-based 7xxx series alloys. The addition of magnesium, copper and chromium elements gives 7075 aluminum extremely strong mechanical properties and extremely high strength. This makes the material the first choice for aerospace, defense and high-performance engineering. The material offers excellent machinability and a cleaner surface finish.
What is The Difference Between 6061 and 7075 Aluminum?
Both are mainly machined aluminum materials, so what are the differences between them? I will introduce it to you in detail below so that you can have a deeper understanding.
6061 vs 7075 Aluminum Density
6061 aluminum and 7075 aluminum have slight differences in density due to the addition of different alloying elements.
| Alloy Grade | Density (g/cm3) | Density (lb/in3) | Relative Difference |
| 6061 Aluminum | 2.70 | 0.0975 | Baseline |
| 7075 Aluminum | 2.81 | 0.1015 | ≈4% Heavier |
You can see that 7075 is about 4% heavier than 6061. This is because 7075 contains about 5.1% – 6.1% zinc.
7075 vs 6061 Mechanical Properties
In the machining industry, mechanical properties are definitely a factor that engineers must consider and will affect your choice of materials. Both 6061 and 7075 are heat treatable. We assume that these two materials are in the same heat treatment state (for example: T6), so that you can see their comparative differences from a mechanical performance perspective.
6061 vs 7075 aluminum Hardness
Hardness determines whether the parts are wear-resistant and the cutting performance of the material. Typically, we can use brinell hardness (HB) to measure the hardness of aluminum alloys. Based on the T6 heat treatment status, let’s make a comparison.
| Material | Brinell HB 500 | Vickers HV |
| 6061-T6 | 95 HB | 107 HV |
| 7075-T6 | 150 HB | 175 HV |
As you can see from the table above, 7075-T6 is about 60% harder than 6061-T6. Therefore, 7075 has better hardness, and it is also very suitable for manufacturing aluminum gears, aluminum pulleys, aluminum shafts, etc. 6061 aluminum, on the other hand, is relatively soft, and its surface is prone to scratches.
In terms of machinability, 6061 is relatively prone to sticking to the tool edge, resulting in tiny burrs on the surface of the parts. he high hardness of 7075 makes the material very crisp to cut, and the surface is also very bright with very few burrs.
6061 vs 7075 Aluminum Strength
In terms of strength, 7075 aluminum is undoubtedly the winner. Below I will use this strength data comparison table to show you their differences more intuitively
| Strength Type | 6061-T6 | 7075-T6 | Gap Magnification |
| Yield Strength | 276 MPa | 503 MPa | 1.82 Times |
| Tensile Strength | 310 MPa | 572 MPa | 1.85 Times |
| Shear Strength | 207 MPa | 331 MPa | 1.60 Times |
6061 vs 7075 Aluminum Yield Strength
The comparison between the two data is quite obvious. For you, the most important indicator is yield strength. It is the critical value at which the material undergoes permanent deformation. 6061 has a relatively low yield strength, but its yield strength is sufficient for most mechanical parts, automotive parts, or electronic enclosures. The yield strength of 7075 is much higher, so it is naturally used in environments with larger loads.
6061 vs 7075 Aluminum Tensile Strength
Tensile strength refers to the force required to directly pull the material apart. In the chart, the tensile strength value of 7075 is as high as 572 MPa, which even exceeds many common structural steels. Therefore, 7075 aluminum is also commonly used in the aerospace industry. As for the tensile strength of 6061, it is relatively standard.
6061 vs 7075 Aluminum Shear Strength
Additionally, shear strength determines a material’s ability to resist being cut. The Shear Strength of 7075 is obviously better than that of 6061.
Other Mechanical Properties Data Sheet
These are other key parameters that structural engineers must know when conducting stress analysis (FEA).
| Property | Unit | 6061-T6 | 7075-T6 |
| Fatigue Strength | MPa | 96 | 159 |
| Modulus of Elasticity | GPa | 68.9 | 71.7 |
| Hardness, Brinell | HB | 95 | 150 |
| Elongation at Break | % | 12% | 11% |
6061 vs 7075 Aluminum Weight
Under the same volume, 6061 aluminum is 4% – 5% lighter than 7075 aluminum. The main reason is that the main alloying element of 7075 is zinc, and zinc has a large atomic weight. The main elements of 6061 are magnesium and silicon, which are relatively light.
6061 vs 7075 Aluminum Price
Price is definitely a point of concern for you. Although the price of metals fluctuates every day, the prices of 6061 and 7075 are relatively stable. The mainstream quotation of 6061 is around $2.17-$3.62/kg, and the mainstream quotation of 7075 is above $4.34-$7.23. It can be said that the price of 7075 aluminum is usually 50% to 70% higher than that of 6061.
6061 vs 7075 Aluminum Corrosion Resistance
6061 aluminum is an excellent corrosion-resistant material. When it is exposed to air or water, it will form a dense oxide layer on its surface. Therefore, even if it is used in humid, salty or industrial exhaust gas environments, 6061 can maintain structural integrity for a long time and is not prone to pitting corrosion.
The corrosion resistance of 7075 aluminum is much worse. In fact, the problem lies in the copper element contained in the material. Copper can accelerate electrochemical corrosion. Therefore, when 7075 is exposed to the air for a long time, white powdery corrosion products will appear, and its surface will also become rough. Additionally, 7075 aluminum also has a fatal weakness, which is stress corrosion cracking (SCC). When it is subjected to high tensile stress and corrosive environments at the same time, 7075 aluminum may suddenly break without warning.
In order to solve these problems of 7075, there are two remedies you can use:
- One is anodizing. You can use electrolysis to generate an artificial oxide film on the surface of aluminum.
- The second is alclad. You can physically roll a thin layer of pure aluminumor 7072 aluminum alloy on the surface of the 7075 sheet.
6061 vs 7075 Aluminum Thermal Conductivity
Before comparing, you must first understand a rule, that is, the higher the strength of the aluminum alloy, the worse its heat dissipation. Naturally, the strength of 7075 is higher than that of 6061, so the thermal conductivity of 6061 must be better.
| Material | Thermal Conductivity |
| Pure Aluminum (1050A) | ≈229 W/m⋅K |
| 6061-T6 | ≈167 W/m⋅K |
| 7075-T6 | ≈130 W/m⋅K |
From the data comparison in the chart, you can also see the difference between the two. Therefore, when you design components that require heat dissipation, such as LED lamp housings or automotive heat exchangers, be sure to choose 6061.
6061 vs 7075 Aluminum Machinability
Machinability is also an aspect you are concerned about. In the CNC machining industry, the harder the material, the better it can be machined. As I mentioned earlier, due to the high ductility of 6061, the chips produced during cutting are often long strips. These long chips can easily wrap around the tool or workpiece, and even scratch the surface of the workpiece. 7075 is highly brittle, and chips will naturally break into small fragments that can be easily washed away by coolant.
Additionally, because 6061 material is soft and sticky, tiny particles of 6061 easily weld onto the cutting edge, forming built-up edges. This can lead to burrs and tiny tear marks on the surface of the parts. On the other hand, parts made of 7075 have an extremely bright and fine-textured surface.
One more thing I must remind you. Regarding tools, 6061 aluminum causes less tool wear, while 7075 aluminum causes tool wear significantly faster than 6061.
6061 vs 7075 Aluminum Applications
In terms of applications, the range and frequency of use of 6061 aluminum are much higher than those of 7075. Due to the machinability and excellent material properties of 6061 aluminum, it is used in various fields, such as the following industries:
- Automotive & Marine: Chassis and frame, bicycle frame, motorcycle part, boat hull deck
- Architecture: Window frames, door frames, ladders
- Industrial and manufacturing: Precision machining, aluminum parts, brackets
- Consumer Electronics: Mobile phone back panels, computer casings
- Casting: Aluminum enclosure, aluminum die casting
7075 is expensive and wear-resistant, so parts made of this material are more commonly used in extreme environments.
- Aerospace: Wing spars, UAV arms
- Sports Equipment: Carabiners, trekking poles, chainrings
- Mold Making: Injection molds
6061 vs 7075 Aluminum Properties Table
Here are some performance data comparisons that have not been mentioned above, so that you can get a more comprehensive understanding.
Physical Properties Sheet
| Property | Unit | 6061-T6 | 7075-T6 |
| Electrical Resistivity | Ω·cm | 3.99 \times 10^{-6} | 5.15 \times 10^{-6} |
| Melting Point | ℃ | 582 – 652 | 477 – 635 |
| CTE | μm/m⋅K | 23.6 | 23.4 |
Chemical Composition Sheet
| Element | Symbol | 6061 | 7075 |
| Aluminum | Al | 95.8 – 98.6% | 87.1 – 91.4% |
| Zinc | Zn | Max 0.25% | 5.1 – 6.1% |
| Magnesium | Mg | 0.8 – 1.2% | 2.1 – 2.9% |
| Copper | Cu | 0.15 – 0.40% | 1.2 – 2.0% |
| Silicon | Si | 0.40 – 0.80% | Max 0.40% |
| Chromium | Cr | 0.04 – 0.35% | 0.18 – 0.28% |
| Iron | Fe | Max 0.70% | Max 0.50% |
| Titanium | Ti | Max 0.15% | Max 0.20% |
| Manganese | Mn | Max 0.15% | Max 0.30% |
Conclusion
The above is the complete comparison of 6061 aluminum and 7075 aluminum. After reading the entire article, I believe you will be able to choose the most appropriate material for your solution. Of course, if you still have any hesitations, feel free to communicate with our DSR company. DSR is a professional CNC machining company that can provide you with customized aluminum machining services. We can produce high-quality aluminum parts for you. Our service quality has been ISO 9001 certified, so you can rest assured! If you have any needs, please contact us immediately.
FAQ
Q1: What are the disadvantages of 7075 aluminum?
A: The disadvantages of 7075 aluminum are processing limitations, corrosion resistance and cost.
Q2: What are the disadvantages of 6061 aluminum?
A: 6061 aluminum alloy’s disadvantages are limited mechanical strength and the material’s tendency to form built-up edges during CNC machining.
Q3: What is the strongest type of aluminum?
A: 7075-T6 aluminum alloy is generally recognized as the strongest grade.
Q4: What is military grade aluminum?
A: It refers to any aluminum alloy material that meets U.S. military standards (MIL-SPEC). This term is commonly used to describe 7075 aluminum alloy or 6061 aluminum alloy.
Q5: Is 6061 or 5052 aluminum stronger?
A: In fact, 6061 aluminum alloy is stronger than 5052, about 40% stronger.
Q6: What aluminum can you not weld?
A: High-strength aluminum alloy grades of 2000 series (such as 2024) and 7000 series (such as 7075).
Q7: What filler rod for 6061 aluminum?
A: In most cases, you can choose ER4043 or ER5356.
Q8: Can you MIG weld 6061 aluminum?
A: Yes. MIG is the most efficient method for welding 6061 aluminum alloy in the industry.
Q9: Is 6061 or 5052 aluminum stronger?
A: 6061 aluminum alloy is significantly better than 5052 in strength. 6061 is a heat-treatable alloy and its yield strength can reach 276 MPa. 5052 is a non-heat treatable alloy and can only rely on cold working deformation to increase strength. Its H32 state yield strength is only about 193 MPa.
Q10: What’s 1 lb of aluminum worth?
A: The benchmark price for pure aluminum ingots is typically around $1.00 to $1.20.
Q11: What is the best grade of aluminum for strength?
A: Undoubtedly, 7075-T6 aluminum alloy is the best choice, with a tensile strength of up to 572 MPa.
Q12: Is 7075 aluminum as strong as steel?
A: This depends on the situation. If 7075 aluminum is compared to common low-carbon steel, its strength is certainly greater than these steels. However, when compared to high-strength alloy steel, the strength value of 7075 aluminum is far inferior to theirs.
Q13: Why is 7075 aluminum so expensive?
A: There are two main reasons. One is the raw material formula. 7075 aluminum alloy contains a large amount of zinc and copper, both of which are more expensive than pure aluminum. The second is the production process. 7075 is an extremely difficult material to process, has a high scrap rate, and the material has very high requirements formachining technology.
Q14: Is 7075 aluminum stronger than carbon fiber?
A: If you only compare tensile strength and specific strength, carbon fiber is stronger than 7075 aluminum, and its tensile strength can reach more than 5 times that of 7075.
Q15: What are the three grades of aluminum?
A: 3003 aluminum alloy, 5052 aluminum alloy, 6061 aluminum alloy.
Q16: What does the T stand for in 6061-T6?
A: The “T” stands for “Treatment”, specifically referring to materials that have undergone a specific heat treatment and tempering process.
Q17: Which is better, 6061 or 6063 aluminum?
A: 6061 aluminum alloy offers better strength and machinability, and its tensile strength is approximately 30% higher than 6063. 6063 aluminum alloy has excellent extrusion properties and surface treatment effects. And its anodized effect is also better than 6061.
Q18: What is the cheapest grade of aluminum?
A: 1100 aluminum alloy is the lowest priced grade on the market.
