Commonly used welding methods for titanium and titanium alloys include: melt welding, brazing, solid phase bonding, mechanical bonding, etc. Among them, fusion welding is the most widely used and can be divided into: arc welding, electron beam welding, resistance welding, etc. Inert gas is used more.
The weldability of titanium materials depends on the chemical activity and physical properties of the material itself. At room temperature, the surface of titanium has a thin and dense oxide film with stable performance. As the temperature increases, the activity of titanium increases sharply. When the welding temperature is higher than 600°C, the dense oxide film is destroyed, and gas can diffuse into the interior of the metal through the loose oxide film and mix with elements such as hydrogen, oxygen, and nitrogen. Violent chemical reactions occur, and these elements exist as interstitial impurities in titanium, causing the performance of the welded joints, especially the plasticity, to decrease. The presence of hydrogen is often the cause of pores and cold cracks in welding.
Before welding titanium materials, the dirt, oxides and gas-enriched metal layer on the surface of the workpiece should be completely removed through mechanical cleaning or chemical cleaning.
