The application of titanium alloy welding technology in shipbuilding and the requirements for the properties of titanium materials

Titanium materials possess characteristics such as high specific strength, resistance to seawater and marine atmospheric corrosion, non-magnetism, sound transmission, resistance to impact and vibration, and good processability (malleability). They are an excellent material for ships. For ship materials, welding technology is an important processing method for their structural manufacturing. The adaptability of various ship titanium and titanium alloys to welding processing, as well as the quality of their welding performance, directly affect their application in ship structures.

There are numerous types and grades of titanium materials, and the performance requirements for them vary depending on the application field. For marine titanium alloys, the main application functions are the resistance to corrosion in seawater and marine atmosphere, high specific strength, high toughness, and excellent processing performance. Due to the wide application range of titanium materials in the shipbuilding industry, such as ship structures, propulsion systems, power systems, electronic information systems, auxiliary systems, and special devices, various performance, grade, and specification titanium alloy materials are required.

When welding for shipbuilding purposes, the principle of equal strength is usually followed, and the best combination of strength, plasticity and toughness is achieved.

Therefore, when selecting welding materials:
①Generally, homogeneous welding materials are selected.

②To improve the plasticity of the joint, welding materials with a lower alloying degree than that of the base material can be used;

③To enhance the plasticity of the weld metal, the content of interstitial elements in the welding wire should be lower than that in the base material. Based on the regression analysis of the research results and test data on the application of titanium alloy welding in ships over the years, it can be known that to achieve equal strength between the weld metal and the base material, generally, the alloy composition of the welding wire should be 1 Al equivalent lower than that of the base material.

In order to keep the content of impurity elements in the weld metal after welding at a low level, the original content of impurity elements in the welding wire must be strictly controlled. The reliability of the welded joint of marine titanium alloy is largely related to the structural shape of the joint. When performing stress relief heat treatment for marine titanium alloy welded structures, the heat treatment process system should be determined according to the characteristics of different alloys to achieve the best heat treatment effect.

Most marine titanium alloys possess excellent welding processing properties. During the application of the alloys, based on the characteristics of various alloys and the operating conditions of the structures, it is crucial to correctly design the joint form, reasonably select the welding materials, formulate reasonable welding processes, provide excellent and reliable gas protection in the welding hot zone, and correctly adopt stress-relieving measures to achieve welding joints with excellent comprehensive performance for marine titanium alloys.