Application of Titanium in Naval Equipment

Titanium is the most promising metal material for naval equipment. It is widely used in surface ships, underwater submarines, deep submersibles, underwater weapons, communication equipment and other fields all over the world. In the nuclear submarine, the condenser, heat exchanger, sonar shroud, sea pipeline system and bellows are made of titanium. Titanium is also widely used in the pressure shell, diesel engine gas exhaust system, sonar shroud, sea pipeline system, bellows, pumps and valves of conventional submarines (636, k877, etc.). It has sailed through the global waters of the Arctic, Antarctic, equator, Pacific, Indian Ocean and Atlantic Ocean, and solved the problems of design allowable stress and selection of safety factor. Titanium is also used in the water jet propulsion devices of various submarines in the United States and Japan, which effectively overcomes the adverse effect of large induced current caused by cutting the earth's magnetic line of force when sailing with copper alloy.

2.1 Pressure shells of submarines and deep submersibles

When the submarine structure is fixed, the ultimate submergence depth of the submarine is directly proportional to the product of the yield strength of the shell material and the shell thickness. Increasing the diving depth by thickening the pressure shell will reduce the effective load of the submarine. If the effective load is maintained, the size of the submarine will be increased to the extent that it can not be used in practice. Therefore, materials with higher specific strength must be considered. Among several materials currently available for submarine shell, titanium alloy has the best performance (see Table 1 for specific comparison). Table 1 shows that titanium alloy is very advantageous as pressure resistant shell material for submarines and deep submersibles.

Properties of Several Deep Submarine Pressure Shell Materials

Examples of the application of titanium in the pressure shell of submarines and deep submarine

2.2 propeller, propeller shaft and water jet propulsion

Cast titanium alloy has high specific strength, high corrosion fatigue resistance and good cavitation resistance (see Table 3). It is an ideal propeller material, especially super cavitation propeller material. Titanium alloy propeller has the advantages of light weight, high propulsion efficiency and long service life.

Mechanical properties of propeller materials

2.3 Heat Exchangers and Condensers

Titanium has excellent corrosion resistance to clean, polluted and sand containing static and dynamic water. High cooling water velocity and thin-walled condenser tube are allowed to improve heat transfer capacity and reduce the weight of condenser. The adhesion of titanium tube is small, and the liquid condenses in bead shape on the surface of titanium. The condensation rate of titanium is more than 29.3% higher than that of copper; The condensation rate is 35% higher than that of 304 stainless steel; The condensation rate is more than 17.5% higher than that of 316 stainless steel, which is also beneficial to heat transfer. The cleanliness coefficient of titanium tube is higher than that of copper alloy tube. The above factors make the thermal conductivity of titanium lower than that of B30 copper alloy, but the heat transfer efficiency is equal to or slightly higher than that of B30. At the same time, the vibration isolation allowance of titanium tube is also higher than that of B30 tube.