In the world of aluminum alloys, strength, corrosion resistance, and formability are the three most important factors that determine an alloy’s suitability for engineering applications. Among the many aluminum grades available, 5251, 6061, and 5083 are widely used in industries such as aerospace, marine, and automotive.
But when it comes to choosing the right alloy, one question often arises: how strong is 5251 aluminum compared to 6061 or 5083?
In this article, SASAALUMINUM explores the differences between these three alloys in terms of mechanical strength, composition, applications, and performance, helping engineers and manufacturers make informed decisions for their projects.
1. Introduction: Understanding Aluminum Alloy Series
Aluminum alloys are categorized into series (1xxx to 7xxx) based on their major alloying elements and properties.
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5xxx Series (Magnesium Alloys): Non-heat-treatable, excellent corrosion resistance, good strength (e.g., 5251, 5083)
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6xxx Series (Magnesium-Silicon Alloys): Heat-treatable, good strength and machinability (e.g., 6061)
Why Compare 5251, 6061, and 5083?
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5251 – Lightweight and corrosion-resistant, medium strength, excellent formability.
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6061 – Strong, versatile, and heat-treatable; used in structural applications.
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5083 – Marine-grade alloy, high strength, exceptional corrosion resistance in seawater.
Each alloy serves a specific purpose — and understanding their mechanical strength helps in selecting the most cost-effective and durable material.
2. Chemical Composition Comparison
| Element | 5251 (%) | 6061 (%) | 5083 (%) | Role in Alloy |
|---|---|---|---|---|
| Magnesium (Mg) | 1.7 – 2.8 | 0.8 – 1.2 | 4.0 – 4.9 | Improves strength and corrosion resistance |
| Silicon (Si) | ≤ 0.40 | 0.40 – 0.80 | ≤ 0.40 | Enhances machinability |
| Iron (Fe) | ≤ 0.50 | ≤ 0.70 | ≤ 0.40 | Minor impurity |
| Copper (Cu) | ≤ 0.15 | 0.15 – 0.40 | ≤ 0.10 | Improves strength, reduces corrosion resistance |
| Manganese (Mn) | 0.10 – 0.50 | ≤ 0.15 | 0.40 – 1.0 | Increases strength and ductility |
| Chromium (Cr) | ≤ 0.15 | 0.04 – 0.35 | 0.05 – 0.25 | Grain stabilization |
| Zinc (Zn) | ≤ 0.15 | ≤ 0.25 | ≤ 0.25 | Minor alloying element |
| Aluminum (Al) | Balance | Balance | Balance | Base element |
Key Differences
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5251 has moderate magnesium content, giving it balanced strength and formability.
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6061 includes silicon and magnesium, making it heat-treatable and stronger.
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5083 has the highest magnesium content, giving it superior strength among non-heat-treatable alloys.
3. Mechanical Properties Comparison
| Property | 5251 (H14) | 6061 (T6) | 5083 (H116) |
|---|---|---|---|
| Tensile Strength | 210–250 MPa | 290–320 MPa | 305–355 MPa |
| Yield Strength | 130–160 MPa | 240 MPa | 215 MPa |
| Elongation | 10–12% | 12% | 10–12% |
| Brinell Hardness | 65–75 HB | 95 HB | 80–90 HB |
| Modulus of Elasticity | 70 GPa | 69 GPa | 71 GPa |
| Density | 2.68 g/cm³ | 2.70 g/cm³ | 2.66 g/cm³ |
Summary of Strength
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6061 Aluminum: The strongest among the three, especially after heat treatment (T6 temper).
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5083 Aluminum: Slightly lower than 6061 in strength but offers much better corrosion resistance.
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5251 Aluminum: Medium strength, but the best in formability and ease of fabrication.
4. 5251 Aluminum – Medium Strength with High Formability
5251 aluminum is a non-heat-treatable alloy that gains strength through cold working (strain hardening). It is often used in aerospace, marine, and automotive applications that require moderate strength and excellent corrosion resistance.
Key Strength Characteristics
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Tensile Strength: Around 230 MPa (H14 temper)
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Yield Strength: Around 150 MPa
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Hardness: 70 HB average
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Strength Type: Moderate, derived from cold work
Performance Summary
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Not as strong as 6061 or 5083 but much easier to form and weld.
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Maintains good mechanical performance in both cold and marine environments.
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Ideal for applications that prioritize flexibility and surface finish over extreme strength.
5. 6061 Aluminum – Heat-Treatable High Strength Alloy
6061 aluminum is one of the most widely used structural alloys due to its excellent combination of strength, corrosion resistance, and machinability. It belongs to the 6xxx series, which means it can be heat-treated to increase its strength significantly.
Key Strength Characteristics
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Tensile Strength: Up to 320 MPa (T6 condition)
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Yield Strength: 240 MPa
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Hardness: Around 95 HB
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Strength Type: Precipitation hardening (heat treatable)
Performance Summary
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Strongest of the three alloys in the T6 condition.
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Slightly heavier but offers superior load-bearing capacity.
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Commonly used in aircraft fittings, automotive parts, and structural frameworks.
However, it is less corrosion-resistant than 5251 or 5083 due to the presence of copper.
6. 5083 Aluminum – Marine-Grade High Strength Alloy
5083 aluminum is the strongest non-heat-treatable aluminum alloy, making it a preferred choice for marine, cryogenic, and pressure vessel applications. Its high magnesium content gives it superior corrosion resistance in saltwater and chemical environments.
Key Strength Characteristics
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Tensile Strength: Up to 350 MPa (H116 temper)
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Yield Strength: 215 MPa
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Hardness: 85–90 HB
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Strength Type: Work-hardened (strain hardened)
Performance Summary
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Offers a unique combination of strength and corrosion resistance.
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Retains mechanical stability even at sub-zero temperatures.
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Commonly used in shipbuilding, tanks, and offshore structures.
7. Strength Comparison Overview
| Alloy | Strength Level | Heat Treatment | Corrosion Resistance | Formability | Weldability |
|---|---|---|---|---|---|
| 5251 | Medium | Non-heat-treatable | Excellent | Excellent | Excellent |
| 6061 | High | Heat-treatable | Good | Moderate | Very Good |
| 5083 | High | Non-heat-treatable | Excellent | Good | Good |
In Simple Terms
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6061 = Strongest for structural use
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5083 = Best for marine and chemical resistance
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5251 = Easiest to form, bend, and weld
Thus, 5251 sits comfortably between 6061 and 5083 in strength but outperforms both in ease of fabrication and corrosion resistance.
8. Tensile and Yield Strength Comparison Chart
The following table highlights the relative performance of these alloys in different tempers:
| Alloy & Temper | Tensile Strength (MPa) | Yield Strength (MPa) | Relative Strength (%) |
|---|---|---|---|
| 5251 H14 | 230 | 150 | 70% (Base reference) |
| 6061 T6 | 320 | 240 | 100% |
| 5083 H116 | 350 | 215 | 95% |
Interpretation
If we take 5251 as a baseline (100%), 6061 is approximately 40% stronger, while 5083 is 35–40% stronger, depending on the temper and application.
9. Applications Comparison
| Application | Best Alloy | Reason |
|---|---|---|
| Aerospace tubing and ducting | 5251 | Lightweight, easy to form and anodize |
| Aircraft frames, automotive parts | 6061 | High structural strength and stiffness |
| Marine structures, ship hulls | 5083 | Exceptional saltwater corrosion resistance |
| Fuel tanks and pressure vessels | 5083 | High strength and chemical resistance |
| Architectural panels and casings | 5251 | Excellent finish and corrosion resistance |
SASAALUMINUM supplies all three alloys, ensuring the right solution for every design — whether the requirement is lightweight flexibility (5251), structural load capacity (6061), or durability in harsh marine environments (5083).
10. Heat Treatment and Fabrication Differences
5251 Aluminum
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Cannot be heat-treated; strengthened by cold working.
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Excellent for bending, rolling, and forming.
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Commonly used in thin-walled tubes and aerospace ducting.
6061 Aluminum
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Heat-treatable (T6 and T651 tempers).
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Requires controlled aging and quenching for full strength.
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Preferred for heavy-duty structural and machined parts.
5083 Aluminum
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Non-heat-treatable, but hardened through strain hardening.
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Excellent weldability and stability under marine conditions.
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Retains mechanical properties at low temperatures.
11. Corrosion Resistance Comparison
| Alloy | Atmospheric | Marine / Seawater | Chemical Exposure |
|---|---|---|---|
| 5251 | Excellent | Very Good | Good |
| 6061 | Good | Fair | Moderate |
| 5083 | Excellent | Excellent | Excellent |
5251 and 5083 both belong to the 5xxx series, meaning they form a natural protective oxide film that makes them highly resistant to corrosion — a key reason they are favored in marine and aerospace tubing.
12. Cost and Availability
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5251 Aluminum – Economical and easy to fabricate; excellent value for general use.
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6061 Aluminum – Moderately priced but requires heat treatment and machining.
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5083 Aluminum – Higher cost due to its marine-grade certification and strength.
Choosing between these alloys often depends on performance vs. cost balance and the specific operational environment.
13. Summary Table – Strength and Use Case
| Category | 5251 | 6061 | 5083 |
|---|---|---|---|
| Alloy Series | 5xxx | 6xxx | 5xxx |
| Strength | Medium | High | High |
| Heat Treatment | No | Yes | No |
| Corrosion Resistance | Excellent | Good | Excellent |
| Formability | Excellent | Fair | Good |
| Weldability | Excellent | Very Good | Good |
| Density (g/cm³) | 2.68 | 2.70 | 2.66 |
| Best Application | Aerospace tubing, interior panels | Structural components, automotive | Marine vessels, pressure tanks |
14. Why Choose SASAALUMINUM
SASAALUMINUM is a professional global supplier specializing in high-performance aluminum materials for aerospace, marine, and industrial use. We provide high-quality 5251, 6061, and 5083 aluminum tubes, sheets, and plates that meet international standards such as ASTM, EN, and ISO.
Our Advantages
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Comprehensive Product Range – Alloys from 1xxx to 7xxx series available.
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Strict Quality Control – Each batch supplied with EN 10204 3.1 MTC.
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Custom Processing – Precision cutting, extrusion, and surface finishing.
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Global Shipping – Reliable delivery to over 40 countries.
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Technical Expertise – Engineering support for alloy selection and performance optimization.
With SASAALUMINUM, you can confidently select the best alloy for your strength, corrosion resistance, and fabrication requirements.
15. Conclusion
When comparing 5251, 6061, and 5083 aluminum alloys, the choice depends on the balance between strength, corrosion resistance, and fabrication needs:
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5251 aluminum offers medium strength, superior formability, and excellent corrosion resistance, making it perfect for aerospace tubing, panels, and lightweight structures.
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6061 aluminum delivers high strength and stiffness, ideal for structural, automotive, and aerospace frames.
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5083 aluminum provides the best corrosion resistance and marine durability, suitable for shipbuilding and chemical processing equipment.
In summary, 5251 is not as strong as 6061 or 5083, but it remains one of the most balanced and practical alloys for applications requiring strength, flexibility, and ease of fabrication.
With expert supply and quality assurance from SASAALUMINUM, industries worldwide can depend on reliable, high-performance aluminum solutions for every project.
Post time: Oct-28-2025