Titanium alloy is a metal material with excellent performance, widely used in fields such as aviation, aerospace, chemical, petroleum, power, medical, construction, sports equipment, etc. Welding of titanium alloy is an important processing technology, but it is also a difficult one because titanium alloy is prone to react with elements such as oxygen, nitrogen, and hydrogen in the air at high temperatures, leading to a decrease in weld quality and performance degradation. Therefore, the welding of titanium alloys requires special methods and equipment to ensure the integrity and reliability of the weld seam.
1. Tungsten inert gas arc welding (GTAW): This is an arc welding method that uses non melting tungsten electrodes and inert gas protection, suitable for butt, corner, and lap welding of titanium and titanium alloy plates, pipes, and special-shaped parts with a thickness of 0.5-10mm. The advantages of this method are high weld quality, small deformation, flexible operation, and no need for metal filling. The disadvantage is that the welding environment is strictly required, and it needs to be carried out under argon protection, otherwise it will cause pollution such as oxidation and nitrification of the weld seam, resulting in a high consumption of argon gas.
2. Electron beam welding (EBW): This is a method of welding that utilizes high-speed electron bombardment to generate heat energy on the surface of workpieces. It is suitable for butt, corner, and lap welding of titanium and titanium alloy plates, pipes, and special-shaped parts with a thickness of 0.1-150mm. The advantages of this method are that it can be carried out in vacuum, avoiding gas pollution, having a large aspect ratio of the weld seam, small deformation, and high efficiency. The disadvantage is that the equipment is complex and expensive, with high requirements for workpiece preparation, which is not suitable for large or complex shaped workpieces.
3. Laser welding (LW): This is an efficient and precise welding method that uses a high-energy density laser beam as a heat source. It is suitable for butt, corner, and lap welding of titanium and titanium alloy plates, pipes, and special-shaped parts with a thickness of 0.1-10mm. The advantage of this method is that it can be carried out in the atmosphere, only requiring side blowing of inert gas protection, with a large depth to width ratio of the weld seam, small deformation, fast speed, and can achieve automated or robotic operations. At the same time, it can also be carried out in a glove box or vacuum environment, creating an inert gas or vacuum environment to achieve better welding results. The disadvantage is that there is a strict requirement for workpiece clearance, which is not suitable for thick wall welding and is suitable for welding precision structures of titanium alloys.
4. Plasma arc welding (PAW): This is an arc welding method that uses a high-temperature and high-speed plasma arc as a heat source, suitable for butt, corner, and lap welding of titanium and titanium alloy plates, pipes, and special-shaped parts with a thickness of 0.5-15mm. The advantage of this method is that it can be carried out in the atmosphere, only requiring inert gas protection before and after blowing. The depth to width ratio of the weld seam is large, the deformation is small, and the efficiency is high. The disadvantage is that the equipment is complex and requires high parameters such as nozzle aperture, ion gas flow rate, and welding speed, which is not suitable for curved or variable cross-section workpieces.
5. Brazing (BW): This is a method of using low melting point metals as fillers to achieve metal connections without melting the base material. It is suitable for butt, corner, and lap welding of titanium and titanium alloy plates, pipes, and special-shaped parts with a thickness of 0.1-3mm. The advantage of this method is that it can be carried out at room temperature or low temperature, avoiding heat affected zone and gas pollution, with small deformation, and can achieve multi-layer or multi pass welding. The disadvantage is that special brazing fluxes and fillers are required, which require high surface cleanliness of the workpiece and are not suitable for joints with high loads or working temperatures.
The above five methods have different advantages and disadvantages, and can be selected according to specific circumstances. For the following specific industries and applications, it is recommended to use laser welding technology for titanium alloy welding:
1. Titanium alloy products or structures that require high strength, toughness, corrosion resistance, and high-temperature performance, such as key components in aerospace, nuclear power, chemical and other fields.
2. Titanium alloy products or structures that require lightweighting, cost reduction, and improved production efficiency, such as components in automotive, shipbuilding, medical, and other fields.
3. Titanium alloy products or structures that require complex shapes, small dimensions, or heterogeneous material connections, such as devices in the fields of electronics, communication, biology, etc.
The selection of titanium alloy laser welding equipment can refer to the following factors:
1. Types and compositions of titanium alloys: Different types and compositions of titanium alloys have different mechanical and welding properties, and it is necessary to choose laser welding equipment that matches them to ensure welding quality and efficiency. Generally speaking, α Type and α+β Type titanium alloy ratio β Type titanium alloys are easier to perform laser welding, while β Titanium alloys require higher laser power and speed.
2. Shape and size of the workpiece: The shape and size of the workpiece affect the selection of laser welding equipment, mainly including parameters such as thickness, length, width, curvature, angle, etc. of the workpiece. Generally speaking, the thicker the workpiece, the higher the required laser power; The longer or wider the workpiece, the faster the required laser speed; The more curved or inclined the workpiece is, the greater the laser defocus required.
3. Joint type and requirements: The type and requirements of the joint also affect the selection of laser welding equipment, mainly including the form, position, quantity, strength, airtightness level and other indicators of the joint. Generally speaking, butt joint, corner joint, and lap joint are the most commonly used joint forms, which can be carried out using fixed or mobile laser welding equipment; Special forms of joints such as circumferential seams and threads require the use of rotating or scanning laser welding equipment.
4. Performance and price of equipment: The performance and price of equipment are important factors affecting the selection of laser welding equipment, mainly including stability, accuracy, efficiency, reliability, safety, operability, and other aspects of the equipment. Factors such as the service life, maintenance cost, and energy-saving effect of the equipment should also be considered.
