The amount of aluminum alloy on the ship
At present, the amount of aluminum used in shipbuilding is not much. As far as the world is concerned, the amount used in 2013 accounts for about 1.1% of its total consumption. In 2012, the domestic consumption of rolled aluminum in Japan was 974.4kt, of which the transportation consumption was 159.0kt (the automobile industry was 139.0kt, accounting for 87.42%, the domestic consumption of extruded aluminum was 784.5kt, of which the transportation volume was 141.9kt (automotive industry 131.6) Kt (92.94%), the two aluminum materials accounted for 17.11% of the total consumption in the transportation sector, while the automotive industry accounted for 89.93 of the transportation materials, and the aviation industry and marine engineering used less than 10 %, Japan is a country with an underdeveloped aerospace industry. Therefore, in the aluminum materials used for transportation, it is estimated that the amount of marine engineering will not exceed 5%. Japan’s aluminum consumption has already entered a stable stage, since 2004. The amount of marine engineering and ships has been around 20kt/a. Among the aluminum materials used, thick plates are mainly used, accounting for 88%, and extruded materials are supplemented, but most of the coastal facilities are extruded materials.
The structure of aluminum alloy for Chinese ships is different from that of Japan. Japan is a big country in the manufacture of LNG (liquefied natural gas) ships. There are 4 huge LNG tanks welded with 5083 alloy thick plates. The plate consumption is about 4kt/boat, China The LNG ship is made of low-temperature brittle Fe-Ni-Mn steel. China only uses some thick plates to make small and medium-sized ships. It is estimated that the aluminum materials used in China's shipbuilding industry in 2014 are less than 230kt, which is less than the apparent consumption of aluminum. 1% of the amount. However, as China's progress toward the maritime powers accelerates and increases, the use of aluminum in ships and marine engineering will increase significantly, but the average annual growth rate before 2025 will not exceed 7.5%.
Development of ship aluminum alloy
The industrial production of aluminum began in the world's first aluminum plant - the Pittsburgh Metallurgical Company of the United States was completed and put into production in 1988. In 1891, the shipbuilding industry first applied the aluminum-made marine parts produced by the plant. After more than 120 years of research and development, aluminum The application of materials on ships and ships is becoming more and more widely used in marine engineering and has become one of the most promising materials in these sectors.
The first aluminum alloys used for shipbuilding were Ni-containing Al-Cu alloys, followed by 2XXX alloys, but their resistance to seawater corrosion was limited, limiting their use in the shipbuilding industry.
The 6061-T6 alloy was used in the 1930s and the hull was constructed by riveting. In the 1940s, the 5XXX series alloy was welded and corrosion resistant. In the 1950s, TIG (tungsten inert gas) welding technology was adopted. During this period, the application of aluminum alloy in shipbuilding has made great progress. In the 1960s, the US Navy developed Al-Mg-based 5086-H32 and 5456-H321 alloy sheets, 5086-H111 and 5456-H111 alloy extruded profiles. Due to the H116 and H117 states, Al8Mg5 precipitated along the crystal was eliminated. The compound retina solves their problem of exfoliation corrosion and intergranular corrosion. This is a milestone in the development of aluminum alloys for ships in the 1960s. Subsequently, due to the need for materials with higher yield strength, the 6XXX series alloy was widely used in shipbuilding. In a long period of time, Europe, America, Japan and other countries mainly choose between 5XXX series alloy and 6XXX series alloy. The hull is made of aluminum alloy, while the Soviet Union chooses more 2XXX alloys. Before the reform and opening up, the Chinese shipbuilding industry mainly followed the Soviet Union. Since 1980, it has tracked more countries such as Europe, the United States, and Japan. After 2010, independent innovation has gradually strengthened. Since the 1970s, the research on medium and strong weldable 7XXX series alloys has been increasing, and some progress has been made, which has been applied in shipbuilding.
After the 1970s, the rationalization and light weight of ship structures have been paid more and more attention. The upper structure and armor of large ships use a large amount of aluminum alloy. To this end, a number of aluminum alloys and materials for these applications have been developed during this period, including extruded profiles of special specifications, large-scale extruded panels and castings.