Choosing the Right Aluminum for Near-Water Applications

While aluminum may not be the best material for continuous or permanent submersion, its high strength and light weight make it a popular metal choice for constructing docks, ladders, floating bridges, vessels, and boat trailers. When exposed to water and air, aluminum forms a protective layer of aluminum oxide that helps shield the metal from further corrosion.

Selecting the appropriate aluminum grade for marine environments is crucial. The 3000 series aluminum alloys oxidize quickly. If you need an aluminum alloy that will come into contact with water or moisture, it is essential to use marine-grade aluminum alloys, such as the 5000 series or 6000 series. With proper maintenance, these aluminum grades can ensure long service life for components used in marine applications.

Characteristics of Marine-Grade Aluminum

Although aluminum itself has relatively high corrosion resistance compared to many other metals, additional protection is required in marine applications where it is exposed to water and moisture. Alloying processes combine aluminum with other metals, such as magnesium, to enhance its corrosion resistance, making it more suitable for applications that contact water and saltwater. These aluminum alloys are known as marine-grade aluminum.

Cast and Forged Marine-Grade Aluminum Alloys

Aluminum alloys are typically classified based on the primary alloying elements added to the aluminum and the alloys' responses to mechanical and heat treatment.

Cast aluminum alloys are produced by pouring molten metal into molds of specific shapes and then allowing it to cool.

Forged aluminum alloys are made by rolling, forging, or mechanically deforming solid metal into the desired shape.

Marine-grade forged aluminum alloys typically include aluminum-magnesium-silicon alloys and aluminum-magnesium alloys. These forged aluminum alloys are commonly used in docks, ship lifts, structural shipbuilding, and other marine structural applications.

Cast aluminum alloys are suitable for various types of vessel applications because the casting process can produce complex shapes, such as structural components, brackets, internal fittings, and superstructures. These alloys are often aluminum-silicon or aluminum-magnesium alloys.

5052 Alloy: Advantages of High Fatigue Strength

5052 marine aluminum is a non-heat-treatable aluminum alloy with fatigue strength far exceeding that of most other aluminum alloys. In addition, it has good workability, making it easy to fabricate into complex shapes, and exhibits excellent corrosion resistance in seawater and atmospheric conditions.

6061 Alloy: Workability and Corrosion Resistance

6061 aluminum is a versatile alloy suitable for marine-grade applications. It has excellent corrosion resistance and other mechanical properties. In its annealed state, it offers good workability, and various processes are used in its manufacture. 6061 marine aluminum is available in sheets, plates, and extrusions, making it an ideal choice for various near-water applications.

6061 aluminum alloy adds silicon for enhanced corrosion resistance, and it is easier to machine and weld than 5052 aluminum alloy. This aluminum alloy is commonly used in applications that require additional strength. Given its higher cost, it is often chosen when workability and other properties are more advantageous for the material.

6063 Alloy: Decorative and Structural Uses

6063 aluminum alloy is primarily used for architectural and decorative purposes rather than structural support. It has excellent corrosion resistance, tensile properties, and finishing characteristics. This aluminum alloy can be used for various architectural decorations both inside and outside buildings.

Applications of Marine-Grade Aluminum

Marine aluminum alloys can be used not only for railings, docks, stairs, ladders, and other items and furniture on or near water, but also for non-marine-specific storage facilities and tanks.

Another aluminum product suitable for vessels is aluminum honeycomb panels. These panels offer many advantages and characteristics, including:

• High strength and lightweight
• High impact resistance
• High rigidity
• Shock absorption
• Available in various thicknesses
• Good sound and thermal insulation properties

Advantages of Marine Aluminum

Marine aluminum alloys possess various characteristics that make them highly suitable for marine conditions, including:

• Excellent resistance to saltwater corrosion
• Extremely lightweight with an excellent strength-to-weight ratio
• Available in various grades, plates, sheets, and extrusions
• Suitable for a range of manufacturing processes