Application of Aluminum Alloys in Ships

1 Properties of aluminum alloys for ships

As we all know, the current lightweight development of the shipbuilding industry is inseparable from the application of aluminum alloy materials. The reason is that aluminum alloy materials have the advantages of small specific gravity, good corrosion resistance, good processing and forming performance, good welding performance, and small elastic modulus. Aluminum alloys for ships have excellent corrosion resistance, so aluminum alloy ships must be able to effectively resist the adverse effects of seawater on the use and service life of ships. Seawater is an electrolyte solution, and the corrosion process of seawater to aluminum alloy is an electrochemical corrosion process, which is specifically manifested in the form of pitting corrosion. The corrosion rate of seawater to 5000 series alloys is extremely slow, among which low-magnesium alloys are more corrosion resistant; the corrosion resistance of 6000 series alloys to seawater can reach 100%. For this reason, 5000 series alloys and 6000 series alloys have been widely used in the field of ships. In addition, the corrosion process of aluminum alloys is quite complicated, which is often affected by the properties of the alloy and environmental factors. The environmental factors include humidity, temperature, pressure, stirring, stray current and corrosion medium, etc.; the properties of the alloy include stress and uneven structure. sex etc. It can be seen that the application of aluminum alloys for ships must fully consider its influencing factors, thereby improving the comprehensive performance of aluminum alloy ships.

2 Application of aluminum alloy in civil ship field

The history of aluminum alloy civilian boats can be traced back to the 1880s, when Echer Wyss Company (Switzerland) first made an all-aluminum motorboat on the lake (capacity for 8 people). Since then, many countries have made aluminum alloy motorboats one after another. However, at that time, aluminum alloys had poor corrosion resistance and low strength, so the shipbuilding industry did not make much progress in the application of aluminum alloys. It was not until the 1930s that the development of the metallurgical industry re-recognized the application value of aluminum alloys in the shipbuilding industry. At that time, Al-Mg alloys and 6061-T6 alloys with better corrosion resistance appeared. Subsequently, the United Kingdom, the United States, and Japan successively manufactured aluminum alloy ships based on Al-Mg alloys. From the 1950s to the 1960s, the application of aluminum alloys in the shipbuilding industry entered a period of rapid development. Typical achievements during this period include the development of aluminum-TIG welding technology, the development of 5486-H32 and 5456-H32 aluminum alloy plates (USA) , The production of Chinese all-aluminum riveted structure hydrofoil boats. From the 1970s to the 1980s, affected by the reduction of aluminum prices, the development of MIG/TIG inert gas shielded welding technology, and the requirements for lightweight and rationalized ship structures, the application of aluminum alloys in the shipbuilding field entered a new period. Dozens of large aluminum alloy LNG ships of 120,000 to 130,000m³ were built. Since the 1980s, various large, medium and small aluminum alloy yachts have been made.

3 Application of aluminum alloy in the field of military boats

In terms of naval architecture, it is believed that the light weight of the ship structure can increase the speed of the ship, reduce the operating cost, improve the operating sensitivity, extend the journey, and reduce maintenance. Based on this, aluminum alloys are widely used in the field of military ships to complete arduous tasks such as assault or search and rescue. Since the 1920s, aluminum alloy materials have been used in the field of warships, and the application of aluminum alloys to American warships is the most common. At this stage, shipyards already have the technology to manufacture a variety of aluminum alloy ships, such as fast attack craft, auxiliary military airships, patrol boats and large high-speed ferries.

4 Application of aluminum alloy in work boat field

Practice has proved that aluminum alloy workboats have the advantages of long service life, low maintenance requirements, and fast driving speed. Among them, aluminum alloy small boats have a service life of at least several decades, and the corrosion of external forces is very small. For decommissioned aluminum alloy ships, it is often caused by backward manufacturing technology. The corrosion resistance of 5000 and 6000 series aluminum-magnesium alloys to marine climates is particularly remarkable.

5 Prospects for the development prospects of aluminum alloys for ships

Compared with other means of transportation, ship transportation is the slowest. With the strengthening of the trend of global economic integration, the application range of ships is wider and the performance requirements are higher. Among them, the increase of ship speed is an inevitable choice for the improvement and development of aluminum alloy ships. If you want to maximize the speed of ship transportation, it is of great significance to reduce the weight of the ship and reduce the water resistance. If the two are combined, the effect will be even greater. The current rapid development of aluminum alloy high-speed boats is the best evidence for this assertion. For aluminum alloy ships, replacing oil with liquefied natural gas (LNG) is an inevitable choice to deal with the unstable situation in the oil market. Liquefied natural gas is an energy source with a liquefied environment <-162°C, which must be stored in low-temperature resistant metal containers, such as stainless steel, nickel steel, aluminum alloy, etc. Considering that aluminum alloy has the characteristics of excellent seawater corrosion resistance, good welding performance, and light weight, its application value is obviously much higher than other metal materials.

To sum up, ship transportation is very important. Aluminum alloy ships have the advantages of small specific gravity, good corrosion resistance, good processing and forming performance, good welding performance, and small elastic modulus. Therefore, measures must be taken to increase the running speed of aluminum alloy ships to a certain height, thereby meeting the development requirements of economy and trade. In addition, the shipbuilding industry should unite with the aluminum processing industry to realize the aluminum and light weight of ships as soon as possible, so that the production level of aluminum alloy ships will be higher and the application effect will be better.