Aluminum's New Application Field - Aluminum for Maritime Use

Industrial aluminum is used in shipbuilding

Since 1891, industrial aluminum profiles have been used in shipbuilding for nearly a century. With the rapid development of shipbuilding industries both domestically and internationally, the lightweighting of ships is gaining increasing attention. Due to the low density, high strength, and strong corrosion resistance of industrial aluminum materials, they are highly suitable for the harsh marine environment. Moreover, the processing cost of industrial aluminum materials is relatively low, making the use of these materials for ship manufacturing more economical. From the perspective of ship designers, vessels manufactured using industrial aluminum profiles can achieve higher speeds under the same power conditions and also have a longer service life. As a result, the technology for shipbuilding using industrial aluminum profiles has made significant advancements in recent years, providing a broad market for a large quantity of aluminum materials.

Industrial aluminum for shipbuilding - four advantages

1. Excellent welding performance

Welding presents more pronounced advantages compared to riveting, as in shipbuilding, the lost properties due to welding cannot be restored through reheat treatment. However, industrial aluminum profiles possess excellent weldability with good crack resistance. Additionally, the performance of welded joints after welding is not significantly different, making them highly suitable for welding applications in shipbuilding.

2. Excellent corrosion resistance

After coming into contact with air, aluminum forms a dense and strong oxide film on its surface, known as aluminum oxide, which effectively resists the corrosion from various elements present in seawater. Coupled with anodizing technology, industrial aluminum profiles can maintain a highly stable form when exposed to seawater.

3. Low density, light

With a density only equivalent to one-third of iron, aluminum contributes to significantly lighter vessel structures when using industrial aluminum profiles for shipbuilding. This leads to improved speed and fuel efficiency for ships of the same size, allowing for longer cruising distances with the same amount of fuel.

4. Good cold and hot forming performance

During the construction of ships, both cold working processes (such as bending, rolling, forming, and stamping) and hot working processes (such as hot bending and pyrotechnic shaping) are involved. Therefore, it is necessary for marine-grade aluminum alloys to be easily processed into various shapes, without causing defects like cracks during processing. Furthermore, the processed materials should still meet the required performance standards in terms of strength, corrosion resistance, and other properties.

Industrial aluminum for shipbuilding - Field of application

1. Aircraft carrier

In terms of the application of industrial aluminum profiles on aircraft carriers, they are used for various purposes, ranging from large components like take-off and landing decks to smaller elements such as cabin decorations and kitchen equipment. It's estimated that each foreign aircraft carrier uses around 1000 tons of industrial aluminum profiles. This usage dates back to as early as 1961, when the U.S. aircraft carrier "USS Enterprise" incorporated these materials into its construction.

2. Speedboats and high speed boats

Long-term maritime navigation demands materials with excellent corrosion resistance and weldability. As early as 1988, China used 5A01 alloy sheets, profiles, forgings, and welding wire to construct the "Fei Yu" hydrofoil. In its construction, semi-automatic pulsed argon arc welding and a steel rotating frame-lama device were employed.

3. Working ship

Aluminum ship hulls require minimal maintenance. They are durable and have a higher cruising speed, which makes them a more cost-effective choice for maritime professionals, leading to increased operational efficiency.

4. LNG (liquefied natural gas) cargo ship

LNG (Liquefied Natural Gas) can serve as a substitute for petroleum energy, and its demand becomes more urgent during oil crises. LNG is created by liquefying natural gas at temperatures lower than -162°C, necessitating metals with excellent low-temperature performance for its storage and transportation. Typically, aluminum alloys, nickel steel, and stainless steel are used, with aluminum alloys being favored due to their strong resistance to seawater corrosion, as well as their light weight and good welding properties.

There are two main technologies for constructing LNG carriers: membrane-type (using insulation barriers) and Moss-Rosenberg. The distinctive feature of Moss-Rosenberg vessels is their large spherical tanks (each ship has at least 5), made from wider aluminum-magnesium alloy plates, which are joined using a specialized high-current gas metal arc welding process.

Industrial aluminum for shipbuilding - application advantages

Aluminum alloys have characteristics such as low density and modulus of elasticity, corrosion resistance, weldability, ease of processing, non-magnetism, and good performance at low temperatures. They offer the following advantages when used in ships:

-Due to its low density, it reduces the overall weight of the ship, allowing for reduced engine capacity and increased speed. This results in reduced fuel consumption and savings in fuel costs. It also improves the ship's -length-to-width ratio, stability, and maneuverability. Additionally, it enables increased payload, leading to extra profit.

-Excellent corrosion resistance leads to reduced maintenance costs, including painting expenses, and extends the service life (often over 20 years).

-Good processability facilitates various forms of processing such as cutting, stamping, cold bending, forming, and machining. This is ideal for streamlining ship structures. Large-sized, wide, thin-walled profiles can be extruded, reducing the number of weld seams and optimizing ship structure for lightweighting.

-Favorable welding properties allow for easier welding processes.

-Low modulus of elasticity absorbs impact stress, enhancing safety.

-Aluminum waste is easily recyclable, promoting circular use.

-No low-temperature brittleness, making it suitable for low-temperature equipment.

-Non-magnetic properties ensure compasses remain unaffected. All-aluminum vessels can avoid underwater mine attacks, making them suitable for minesweepers.

-Resistant to pests and dry deformation, does not burn, and offers better fire safety.

Industrial aluminum for shipbuilding and developed countries gap

While aluminum materials are of significant importance for achieving lightweight in maritime transportation, they are hindered by their high cost, impeding their widespread adoption. This issue is particularly notable in the utilization of aluminum alloys for structural components in maritime transportation vehicles. If the same components are made from aluminum alloys, the cost can be more than three times that of steel materials. To effectively control production costs, continuous and large-scale manufacturing is required for maritime transportation vehicles, demanding stability in raw material prices.

The application of aluminum alloys in the maritime transportation sector has already commenced, yet some technical challenges persist, affecting the broader utilization of aluminum materials. Among these challenges, prominent ones include the welding technology for aluminum plates and steel plates, as well as the corrosion resistance of aluminum alloy materials for ship bodies. Further refinement is also necessary for the extrusion of large, complex, and heavy-section aluminum alloy profiles used in ships.

Industrial aluminum for shipbuilding - China's share in the world

China's shipbuilding industry's global market share is noticeably increasing, positioning China as one of the significant shipbuilding hubs worldwide. The trend of industrial relocation in the international manufacturing sector presents a substantial opportunity for the development of China's shipbuilding industry. In 2007, due to rapid economic growth, shipbuilding, ship repair, and ship-related industries experienced comprehensive expansion. A total of 1,059 shipbuilding enterprises above a certain scale achieved a combined industrial output value of 256.3 billion yuan, with an industrial value-added of 68.3 billion yuan, marking a year-on-year increase of 53% and 70% respectively. The main business revenue exceeded 20 billion yuan, with growth exceeding 60%.

From January to November in 2007, the total profits of national-scale shipbuilding enterprises amounted to 18.5 billion yuan, a year-on-year increase of 7.85 billion yuan and a growth rate of 136%. After a phase of rapid development in the shipping industry, China will gradually free itself from the limitations imposed by foreign production technology on aluminum alloys. Instead, aluminum alloy materials will be increasingly used for ship hulls and superstructures. The potential for aluminum materials in the maritime transportation sector is expected to be even greater.