Ships are for civilian use and naval vessels are for military use. Ships are often requisitioned during wartime to transport military supplies. A ship is a large ship, and specifically refers to a ship sailing on the sea; a boat refers to a lighter boat, such as a motorboat and a lifeboat, but also refers to a small military vessel and a military vessel that dives underwater; a ship is a large warship with a displacement generally greater than 500t. Titanium and titanium alloys have excellent resistance to corrosion in seawater and ocean atmospheres. They are the most suitable materials for the manufacture of ship parts and marine facilities: propeller propellers, submarine whip antennas, and shells, seawater pipelines, condensers, and Heat exchangers, acoustic systems, fire-fighting equipment, etc. are all titanium and titanium alloys. The applied alloys mainly include industrial pure titanium, Ti-6Al-4V, Ti-6Al-4VELI, Ti-6Al-2Nb-1Ta-0.8Mo, Ti-3Al-2.5V, etc. In addition, Ti-Ni shape memory alloys are used in It is also used in submarines to make welded pipe joints.
Titanium alloy submarine
The Soviet Union is the world leader in the use of titanium alloys to manufacture submarines and nuclear submarines. It is also the first country to use titanium alloys to manufacture deep-sea pressure-resistant titanium alloy shells. In most years, the amount of titanium alloy thick plate and thick wall pipes is nearly 10,000 tons, accounting for 1/3-1/2 of the output of titanium alloy that year. Titanium alloy has various properties for manufacturing shells: high strength performance, excellent fatigue resistance, non-magnetic, and can withstand depth bomb explosion shock waves. Titanium alloy has good thermal conductivity, which is good for manufacturing submarine heat exchangers. Material. After the disintegration of the Soviet Union in 1991, Russia continued to lead the development of the titanium industry. Titanium alloy plates and strips were rolled in St. Petersburg (called Leningrad in the Soviet era), and the ingots were cast in the Upper Salda Metallurgical Union.
The Soviet Union began to study the application of titanium alloys in ships in the 1960s. The first K162 all-titanium nuclear submarine was launched in December 1968, and the first ALFA-class nuclear submarine was built in 1970. It is said that 6 ships had been built by 1988. The amount of titanium used for the ship is about 3kt, and some of its technical parameters are shown in Table 1.
In the 1980s, the Soviet Union produced six more "Typhoon" class ballistic missile nuclear submarines. The first was built in 1980 and commissioned in 1984. Each of them had a titanium consumption of 9kt, an underwater displacement of 33.8kt, and an underwater speed of about 27kn. The world's largest submarine has a double hull structure. The non-pressure hull is made of high-strength and low-magnetic steel, and the pressure hull is made of titanium alloy. The "Ohio" class nuclear missile submarine that the United States entered service in 1980 is all-titanium and has an underwater speed of 20kn.
Atomic Power Ship
The steam engines, heat exchangers, condensers, etc. of the atomic power (nuclear power) ships of the Soviet era were made of stainless steel, and they often had problems, such as leakage and corrosion, and frequent accidents. Later, they were made of titanium alloy. All these problems are gone, and the engine service life has been extended by 20 to 30 times. Table 2 shows the usage of the Soviet titanium alloy atomic icebreaker.
Titanium fishing boats in Japan
In 1973, the first all-titanium fishing vessel jointly built by Japan Steel Corporation, Toho Titanium Corporation, and Eto Shipbuilding Corporation was 12.5m long, 2.8m wide, and had a total mass of 4.6t. The hull was welded with 2.5mm thick titanium alloy plates. The all-titanium fishing boat is light in weight, corrosion-resistant, does not require surface treatment, is easy to clean up with attached marine organisms, and requires less maintenance. So far, there are more than 20 titanium alloy fishing boats in Japan.
Other main titanium alloy equipment for ships
Sonar shroud. In the early days, sonar shrouds used in ships were mostly made of FRP and stainless steel. After the introduction of titanium alloy, it was gradually changed to be made of titanium alloy. Years of use have proved that the overall performance of titanium alloy is better than that of the other two materials.
propeller. The propeller is a very important equipment for ships and ships. The working conditions and environment are extremely severe. The manufacturing materials must have high strength performance, strong fatigue resistance in seawater, erosion resistance, cavitation corrosion resistance, and good formability. It is suitable for high-speed boats. Materials have higher requirements. The practice has proved that titanium alloy has the best comprehensive performance in today's propeller materials. Since titanium alloys have generally matured, various countries have used titanium alloys to manufacture propellers in various scales. Since the early 1970s, China has used titanium alloys to manufacture propellers and produced hydrofoil speedboat propellers in 1972. According to incomplete statistics, by 2020, nearly 10,000 propellers with diameters of 450mm-1200mm have been produced. The fixed titanium alloy propeller with a diameter of 1200mm weighs about 130kg. Long-term use has proved that the life of titanium alloy propellers is more than 5 times longer than that of copper alloys.
Pumps, valves, and pipes. The working conditions of the pumps, valves, and piping systems of ships and ships are extremely harsh. The service life of copper and stainless steel pipelines is only 2 to 5 years. After the use of titanium and titanium alloy pipelines, the service life is doubled. According to the relevant regulations of the Soviet Union and Russia, the pipeline life should reach three years: First, it should reach the first dock maintenance period, which is eight or nine years; second, the service period should not be less than 15 years; the total life (reliable operation period) ) Should be no shorter than 25-30 years.
