Titanium Materials in Marine Engineering

Titanium and titanium alloys have very useful comprehensive performance, to enhance the technical and tactical performance of naval equipment, enhance the level of marine resources development equipment is of great significance, therefore, since the 1980s, the western developed countries have begun to use titanium materials to replace CuNi alloys, stainless steel, and nickel alloys in their conventional submarines, nuclear submarines, aircraft carriers, surface ships and deep submarine and other equipment. Manufacturing power systems (steam generators and propeller thrusters, etc.), through the sea piping systems, heat exchangers, pressure-resistant shells, sonar systems, smoke pipes, fire protection systems, pumps and valves, communication systems and other equipment and components, which greatly extends the service life of the equipment, reduces the cost of maintenance, improves the safety, carrying capacity and maneuverability and so on. Table 1 gives the typical components of titanium alloy applications on U.S. ships. In addition, in the offshore oil drilling equipment, titanium alloy has begun to be more widely used to improve the safety and reliability of drilling equipment, reduce the weight of the system and operation and maintenance costs, and achieved very good results.

This paper focuses on the use of titanium alloy in marine engineering equipment at home and abroad, including ships, offshore energy development, seawater desalination, and coastal and marine buildings and other aspects of the current situation and development.

Application of titanium materials in ships

(Pressure-resistant) hull

The application of titanium alloy as hull structure material mainly includes three aspects: pressure-resistant shell of submarine, pressure-resistant shell of deep submarine and shell of surface ship.

Pressure-resistant hulls for submarines

In the submarine pressure-resistant shell with titanium, the former Soviet Union walked in the forefront of the world, opened up the use of titanium alloy materials as a submarine pressure-resistant shell of the precedent.

In 1968, the former Soviet Union (Russia) built the world's first titanium alloy multi-purpose nuclear-powered submarine (Papa), with a displacement of 5,200 tons, a length of 100 meters, and a depth of 400 meters, which is a revolutionary step in the application of titanium alloy to large-scale marine structures.

From 1974 to 1981, the former Soviet Union built a series of all-titanium shell nuclear-powered submarines (Alfa class to NATO), displacement of 2,300 tons, length of 80 meters, depth of 600 meters, of which each submarine's titanium alloy dosage of 2,000 tons of the more, a total of 7 built, titanium alloy dosage of more than 14,000 tons.

In 1983, the former Soviet Union built the largest titanium shell nuclear-powered submarine "Komsomolets (Komsomolsk)", with a water displacement of 5880 tons, a submerged displacement of 8,500 tons, a length of 117.5 meters, a maximum depth of 1,200 meters, and the use of titanium alloy amounted to 4,000 tons. Unfortunately, the submarine sank in April 1989 due to a fire.

From 1983 to 1992, the Soviet Union (Russia) built four more "Sierra" series of titanium alloy pressure-resistant hull multipurpose attack nuclear-powered submarines, with a displacement of 7,200 tons (Type 945) and 7,600 tons (Type 945A) on the surface, and 8,100 tons (Type 945) and 9,100 tons (Type 945A) on the submerged side. 9100 tons (945A), length 110 meters, maximum depth 750 meters, the number of titanium alloys used is not known. After the collapse of the Soviet Union, economic constraints forced the Sierra class submarines out of service. Sources say that Russia restarted the maintenance of the Sera-class nuclear submarines and began to recommission them in 2017.

From 1982 to 2000, the former Soviet Union (Russia) has built 15 Akula-class nuclear ballistic missile submarines, with a submerged displacement of 12,800 tons, a length of 110 meters, and a maximum depth of 600 meters, which is currently the main submarine of the Russian Navy.

From 1986 to 2000, the former Soviet Union (Russia) also built 14 "Oscar" class and 6 "Typhoon class" nuclear submarines, respectively, with a submerged displacement of more than 19,000 tons and 48,000 tons, length of 155 meters and 171 meters, depth of 500 meters and 171 meters, respectively. meters, the depth of 500 meters and 400 meters, of which, the Typhoon class for the former Soviet Union (Russia), the largest ballistic missile nuclear submarines, the amount of titanium alloy material for each ship has reached a staggering 9,000 tons of more than China's current annual production of titanium processing material production of about 20%.

With the dissolution of the former Soviet Union, Russia used titanium alloy as a pressure-resistant shell manufacturing nuclear-powered submarines in a long period of time has been put on hold or did not according to the original plan to build the completion of the construction, but with the gradual recovery of Russia's economy and political needs, Russia in 2000 or so and re-opened the titanium alloy pressure-resistant hull of the nuclear submarine manufacturing and restoration project.

The Yasen class nuclear-powered attack submarine was built and launched in 2010 after a delay in delivery due to funding problems since construction began in 1993. The submarine also uses titanium double-hull structure, submerged displacement of 13,800 tons, length of 120 meters, depth of 600 meters, plans to build 12. 2010 delivery to the Navy, code-named AS-12 210-class multi-purpose nuclear attack submarine is currently the most outstanding performance of nuclear submarines on behalf of the submerged displacement of 2,000 tons, length of 71 meters, width of 8 meters, submerged maximum speed of 45 knots (about 90%), the maximum speed of the submerged submarine. The maximum submerged speed reaches 45 knots (about 90Km/h), and the maximum depth can reach 6000 meters. The submarine still adopts the double-hull structure commonly used in Russian submarines, but in order to achieve the designed diving depth, the outer hull is still titanium alloy hull, while the inner hull is made of six huge titanium alloy spherical shells connected to withstand the huge deep-sea pressure.

The former Soviet Union (Russia) has formed a perfect submarine pressure-resistant shell with titanium alloy material technology and application of technology system, but also paid a high price for this, for example, from 1960 to 1970, the former Soviet Union scientists spent 10 years to solve the problem of titanium alloy welding technology. At present, the main titanium alloys used in the pressure-resistant hulls of Russian submarines are two kinds of titanium alloys: Ti-4A1-2V (ПТ-3B) and Ti-2A1-2.5Zr (ПТ-7М). The titanium alloys used in the external pressure-resistant hulls of the 210-class multi-purpose attack submarines and their internal six pressure-resistant spherical hulls are newly developed high-performance titanium alloys of which the specific grades and chemical compositions are not known.