6061 aluminum alloy belongs to the Al-Mg-Si series. It features medium strength, good plasticity, excellent corrosion resistance, and no tendency for stress corrosion cracking, with outstanding weldability. 6061 aluminum alloy is easy to extrude, forge, weld, and machine. Common products include aluminum plates, aluminum coils, aluminum profiles (aluminum rods, aluminum tubes, T-shaped aluminum, etc.).

In seawater, 6061 marine aluminum shows excellent anti-rust performance. Compared with 5-series marine aluminum alloys (such as 5083), it has slightly lower corrosion resistance but higher strength. 6061 T6 and T651 temper materials can be used for superstructures, bulkhead structures, and frames of vessels, mainly for threaded and riveted structures that do not come into direct contact with seawater.

All 6061 marine aluminum products from MC Aluminum are certified by CCS, DNV, ABS, or BV classification societies.

Chemical Composition of 6061 Aluminum Alloy

• Aluminum (Al): ~95.8-98.6% - the base material, providing excellent lightweight properties.

• Magnesium (Mg, 0.8-1.2%) and Silicon (Si, 0.4-0.8%) - form Mg₂Si strengthening phase, improving strength and heat-treatability.

• Copper (Cu, 0.15-0.4%): enhances mechanical strength but slightly reduces corrosion resistance.

• Chromium (Cr, 0.04-0.35%): refines grain structure, improves stress corrosion resistance.

• Iron (Fe), Manganese (Mn), and other trace elements - control impurity content and optimize processing performance.

Technical Specifications of 6061 Marine Aluminum Alloy

Mechanical Properties

Why is 6061 Marine Aluminum Favored in Shipbuilding?

1. Corrosion Resistance: Excellent resistance in atmospheric and freshwater environments. In marine environments, anodizing (film thickness ≥ 15 μm) is recommended to enhance protection and significantly improve salt spray resistance.

2. Mechanical Strength: Provides sufficient structural support to withstand marine wave impact and shock loads.

3. Weldability: Suitable for TIG and MIG welding, with strong and crack-resistant joints.

4. Lightweight and High Strength: Density is only 2.7 g/cm³ - about one-third that of steel - effectively reducing vessel load.

5. Workability: Good machinability and formability, reducing manufacturing time.

Typical Applications

• Structures of speedboats and yachts

• Ladders and support frames for offshore platforms

• Marine outfitting components (railings, gangways)

• Partitions and insulation systems in refrigerated vessels

• Internal frames and deck plating of ships

• Support structures for offshore wind farm maintenance vessels

Comparison with Other Marine Grade Aluminum Alloys

While 6061 aluminum alloy is very popular, its characteristics compared with other marine grade aluminum alloys (mainly the 5xxx series) should be considered:

6061 vs. 5xxx Series: The 5xxx series (such as 5083 and 5086) are magnesium-based alloys known for their excellent seawater corrosion resistance, especially in saltwater environments. However, 6061 aluminum alloy offers higher strength, better weldability, and can be heat-treated to achieve greater hardness and strength (e.g., T6 temper).

6061 vs. 6063: 6063 is another common 6xxx series extrusion alloy known for its superior extrusion performance, better corrosion resistance, and excellent surface quality. However, 6061 generally has higher strength than 6063, making it the better choice for projects with higher strength requirements.