Welding processing of titanium alloys

In recent years, apart from some traditional titanium alloy processing techniques, several new processing methods have emerged, such as low-temperature cutting, laser, ultrasonic, and electromagnetic cutting, etc. Especially with the development of welding technology, the application scope of titanium alloy processing has become more extensive. However, due to the physical and chemical properties of titanium alloys, the welds are prone to oxidation and nitriding during welding, and the joint is sensitive to brittleness. Therefore, welding processing of titanium alloys is very challenging.

(1) Tungsten Inert Gas Arc Welding
Tungsten Inert Gas Arc Welding is the most common method for titanium alloy welding. Under the protection of argon gas, the tungsten electrode serves as the electrode, and the weld metal is well protected. However, this welding method has low welding production efficiency and large post-weld structural deformation. The weld structure and grain are coarse, and it will seriously affect the weld quality in the case of poor protection. It is only suitable for thin plate welding or base welding.

(2) Laser welding is a high-energy-density welding method. Using this method for welding titanium alloys can not only reduce the defects of traditional processing methods, but also effectively refine the weld structure grains and improve the weld performance. However, this welding method has a small power and the laser beam absorbed by the welded workpiece surface is very low. There are some threshold issues. It is only suitable for special materials or occasions with special processing requirements, and is limited to the processing of micro-sized precision parts. Therefore, it is more difficult than traditional processing methods.

(3) Stirring Friction Welding is one of the better plastic connection process methods among many new ones. When using stirring friction welding, due to the low welding heating temperature, the defects in the weld area are the least, and the joint structure and performance are good, which can achieve effective welding of titanium alloys. However, this method has high requirements for the stirring head and its material, and has poor adaptability. The process is not mature, so it can only be applied to the welding processing of simple components.

(4) Electron Beam Welding has a large welding energy, strong penetration, a large weld depth-to-width ratio, and isolates the pollution of the atmosphere. The weld joint has good performance and can achieve the welding of thick titanium plates. However, this method requires welding in a vacuum environment, is limited by the size and shape of the processed parts, cannot be mass-produced, and has high requirements for equipment, resulting in high production costs, thus limiting its application scope.

(5) Laser-Arc Composite Welding is a good welding process for titanium alloys. It combines the advantages of laser welding and arc welding, has concentrated energy density, stable arc, and good weld performance. However, its welding process parameters are many, cannot be effectively controlled, and the operation process is also relatively complex. Therefore, it is only at the research stage at present.

For the welding processing of titanium alloys, regardless of which new technology or method, there are certain advantages and disadvantages to some extent. With the wide application of titanium alloy materials in multiple fields, it is necessary to continuously research new welding processes and methods to improve weld quality and welding production efficiency, ensure the welding quality of titanium alloy structural components and meet the usage requirements.