Titanium welding is typically done using argon, which is used as a shielding gas in the process of Tungsten Inert Gas (TIG) welding. Argon is preferred because it provides an inert atmosphere that prevents oxidation and contamination of the titanium during the welding process. Other welding methods, such as laser-assisted welding, spot welding, and thermal welding, are less commonly used for titanium due to the specific requirements of welding titanium effectively.