Breaking Strength of Aluminum: Properties Comparison

Tensile Test on aluminum

In this blog, you’llAluminum is a lightweight metal known for its corrosion-resistant properties. Plus, its strength-to-weight ratio makes it an important metal in industries like aerospace, automotive, and construction. 

The tensile strength of aluminum refers to the maximum force it can handle before deforming permanently, You can also think of it as the material’s ability to resist breaking under tension varies significantly across alloys and tempers. 

 learn about the factors influencing the mechanical properties of aluminum, the comparison with steel, and its applications. 

Understanding Breaking Strength

Tensile test 

Breaking strength or tensile strength measures any material’s capacity to withstand the maximum stress before breaking under a tensile or pulling force. For aluminum, the breaking strength can be found practically from a tensile test. 

In a tensile test, a sample of aluminum (specific temper or alloy) is pulled until it breaks, necks, or fractures at the desired point. The stress-strain curve generated from this test illustrates: 

• Yield Strength: Stress at which plastic deformation begins.
• Ultimate Tensile Strength: Peak stress before fracture.
• Pure Aluminum: 90 MPa (13 ksi).
• High-Strength Alloys: Up to 572 MPa (83 ksi).

Factors Influencing Aluminum’s Breaking Strength

• Alloy Composition:

  • Pure aluminum (1100 series): 90 MPa.
  • 6061 (magnesium, silicon): 310 MPa (T6 temper).
  • 7075 (zinc, chromium): 572 MPa.

• Processing:

  • Heat-treatable alloys: Strengthened via precipitation hardening.
  • Cold working: Increases strength (e.g., 30 MPa to 165 MPa).

• Environment:

  • Oxide layer: Improves corrosion resistance.
  • High temperatures: Reduce strength by ~50% at 275°C.

Breaking Strength of Common Aluminum Alloys

Different Aluminum alloys and parts

Tensile Strength of Common Aluminum Alloys

The most common aluminum alloys for machining include 6061 and 7075. There are also other alloys that can be compared to 6061, like 6063. 

Comparing Aluminum’s Breaking Strength to Other Metals

Aluminum vs. Steel:

Aluminum’s tensile strength is around 90 – 572 MPa, depending on the alloys, which is lower than steel’s 400 – 965 MPa, but its strength-to-weight ratio is better than steel and many other metals. 

Aluminum has a density of around 2.7 g/cm3 vs 8 g/cm3 for steel. 

Aluminum vs. Stainless Steel:

Compared to stainless steel (505 MPa) aluminum is lighter but not as strong. In aerospace, the strength-to-weight ratio comparison for aluminum and stainless steel (99 vs 63) shows aluminum to be a preferable choice. 

Aluminum vs. Brass:

Aluminum also performs better than brass, which has a breaking strength of 400 MPa. Aluminum has better corrosion resistance as well. 

Titanium and some composites are stronger than aluminum and comparable in strength to weight ratios but their costs limit their extensive use in many industries. You can compare metal strength which also is a good indicator of machinability and expected costs.

Applications of Aluminum’s Breaking Strength

Many applications use aluminum primarily for its tensile strength.

1. Aerospace: High-strength alloys like 7075 and its tempers are used in aircraft frames for their increased strength and low weight. Its resistance to corrosion also ensures longevity in these applications.
2. Automotive: 6061 aluminum is widely used in vehicles to reduce weight from components like panels while maintaining strength. 
3. Construction: 6061-T6 and 6063 alloys have moderate tensile strength and good weldability for beams, aluminum extrusions and window frames. 
4. Marine applications: Aluminum railings and accessories are common on boats and yachts. Alloy 5083-H116 is an aluminum alloy with improved corrosion resistance that is mainly used in shipbuilding.
5. Wires: Pure aluminum grades like 1xxx series aluminum are used in wires for their electrical conductivity and ductility. 

Challenges

Aluminum does not show a clear fatigue limit; steel, on the other hand, has a defined fatigue limit. Aluminum can fail under repetitive loads, and making aluminum parts requires careful cyclic loading considerations. Aluminum machining however, is an easier process compared to steel but

The tensile strength of aluminum decreases when the temperature rises above a certain limit. For most alloys, this is around 150°C. This means aluminum is not the preferred material for high-temperature applications. 

Some alloys, like 7075, which have high strength are expensive and not viable for use in mass production. Comparing aluminum grades can help you decide the best material for your applications.

• Shear strength: Lower than steel.
• Compressive strength: Less robust than steel.

Conclusion

Aluminum’s breaking strength depends on the alloying constituents and temper. Pure aluminum offers 90 MPa, while 7075-T6 reaches 572 MPa. Alloying elements like magnesium and silicon enhance these tensile properties.

Aluminum Machining Service

High-quality aluminum machining services at Prolean-Tech come with part delivery at your facility. 

Request a quote today for a free consultation and to have precisely cut aluminum parts for your assembly.