What is the difference between 5086 and 6061 aluminum?
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There are significant differences between 5086 and 6061 aluminum alloys in terms of composition, mechanical properties, application fields, and performance in specific environments.
When exceptional corrosion resistance is needed in marine environments, 5086 aluminum is the preferred choice.
When structural applications require a balance between strength, workability, and corrosion resistance, 6061 aluminum is the preferred choice.
5086 vs 6061 Alloy Composition
- 5086 Aluminum: Primarily composed of magnesium (3.5-4.5%) with small amounts of chromium, manganese, and other elements. It belongs to the 5000 series and is renowned for its outstanding corrosion resistance, especially in marine environments.
- 6061 Aluminum: Contains magnesium (0.8-1.2%) and silicon (0.4-0.8%) along with small amounts of copper, chromium, and other elements. It belongs to the 6000 series and is known for its good mechanical properties and weldability.
5086 vs 6061 Mechanical Properties
| Property | 5086-H116 (Typical) | 6061-T6 (Typical) |
| Yield Strength | 207 MPa (30,000 psi) | 276 MPa (40,000 psi) |
| Ultimate Tensile Strength | 290 MPa (42,000 psi) | 310 MPa (45,000 psi) |
| Elongation at Break | 12% | 12–17% |
While 6061-T6 has a slightly higher yield strength, 5086 retains higher strength after welding because it is strengthened through cold working rather than heat treatment.
- Elongation and Ductility: 5086 typically has better ductility than 6061, especially in annealed or H32 conditions.
- Fatigue Resistance: 5086 has superior fatigue resistance compared to 6061, making it better suited for dynamic marine environments.
5086 vs 6061 Corrosion Resistance
5086 Aluminum: It has excellent corrosion resistance, especially in seawater environments, making it an ideal choice for marine applications such as hulls and offshore structures.
6061 Aluminum: It has good corrosion resistance, but compared to 5086, it is more susceptible to pitting and stress corrosion cracking in marine environments.
5086 vs 6061 Workability and Manufacturability
- 5086 Aluminum: Not heat treatable; its strength is achieved through cold working. It has excellent weldability, with most of its strength retained after welding. However, stress corrosion cracking may occur under certain conditions.
- 6061 Aluminum: Heat treatable, allowing for multiple temper states (e.g., T6, T651) to achieve the desired strength and hardness. It also has good weldability and is commonly used in structural applications.
Machining Characteristics
- 5086 Aluminum has good formability and excellent weldability, but machining can be difficult.
- 6061 Aluminum is versatile in machining, suitable for bending, stretching, and other cold-working processes, with better cutting performance than 5xxx series alloys.
5086 vs 6061 Weldability and Post-Weld Performance
- 5086: After welding, it retains about 90% of its strength because it is strengthened by cold working rather than heat treatment. It is recommended to use 5356 or 5183 filler wire to avoid cracking.
- 6061: The strength in the heat-affected zone (HAZ) significantly decreases after welding, from about 270 MPa (T6) to about 110 MPa (annealed). Careful selection of filler materials (e.g., 4043 or 5356) is required to minimize cracking.
5086 vs 6061 Formability and Bending
- 5086: Even with thicker sections, it is easier to bend without cracking. It is suitable for applications requiring complex shapes, such as hulls.
- 6061: Bending without cracking is more difficult unless heated (e.g., to 750°F) or annealed. The formability of T6 condition is limited.
5086 vs 6061 Thermal Conductivity and Electrical Conductivity
- Thermal Conductivity: 6061 (170 W/m-K) is better than 5086 (130 W/m-K).
- Electrical Conductivity: 6061 also has higher electrical conductivity (43% IACS vs. 31% IACS).
5086 vs 6061 Common Applications
- 5086 Aluminum: Due to its excellent corrosion resistance, it is the material of choice for marine environments, including hulls, yacht structures, and offshore platforms. Common applications include ship decks, marine engineering structures, and corrosion-resistant containers.
- 6061 Aluminum: Due to its balance of strength and workability, it is widely used in aerospace, automotive, and structural applications, such as aircraft parts, truck frames, and building structures.
5086 vs 6061 Cost and Selection Recommendations
- 5086 Aluminum is more expensive, primarily due to its corrosion resistance and special processing requirements. It is typically more costly because of its marine-grade properties and magnesium content.
- 6061 Aluminum offers great value for the balance between strength, workability, and cost. It is more widely available and more cost-effective for general applications.
5086 vs 6061 Key Considerations for Selection
- Marine Use: 5086 is suitable for prolonged exposure in water, while 6061 can also be used for short-term exposure with proper insulation and coating.
- Strength vs. Formability: 6061 has higher strength in heat-treated conditions, but 5086 is more suitable for welding and bending.
- Fatigue and Corrosion: 5086 has excellent fatigue life and corrosion resistance, making it ideal for dynamic saltwater applications.
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