1. What protective measures should be noted when welding Grade 2 titanium?
When welding Grade 2 commercially pure titanium, strict and effective gas shielding is the most critical requirement, because titanium is highly reactive with oxygen, nitrogen, hydrogen, and carbon at high temperatures. Insufficient protection will cause embrittlement, hardening, cracking, and loss of corrosion resistance.
Full argon shielding: High-purity argon (99.99% or higher) must be used for shielding. It is required to protect the front weld pool, back side, and heat-affected zone until the temperature drops below 300℃.
Back purging: The back of the weld must be protected with argon to prevent oxidation and discoloration.
Trailing shield: A trailing gas shield is recommended for longer welds to extend protection to the cooling weld area.
Cleaning before welding: The surface of the base metal and welding wire must be thoroughly cleaned to remove oil, dust, moisture, oxides, and other contaminants.
Control of welding environment: Avoid drafts, wind, and high-humidity environments. Windproof measures must be taken if welding in open areas.
Avoid contact with other metals: Prevent contact with carbon steel, copper, or other impurities to avoid contamination.
Only with complete and stable protection can the welds maintain good ductility, toughness, and corrosion resistance.
2. Does Grade 2 require pickling and passivation after welding?
In most cases, pickling and passivation are recommended after welding Grade 2 titanium, especially for applications requiring high corrosion resistance.
Welding will produce an oxide layer, discoloration, or slight contamination on the surface, even if protected by argon.
The natural oxide film formed after welding is often uneven and may affect corrosion resistance in severe environments.
Pickling removes oxides, scale, and surface impurities; passivation promotes the formation of a uniform, dense, and stable TiO₂ protective film.
For applications in corrosive environments such as chemical equipment, seawater, marine engineering, and medical devices - pickling and passivation are necessary.
For structural parts not exposed to corrosive media, if the weld surface is bright and free of discoloration, mechanical polishing or light cleaning may be sufficient, but passivation is still recommended for long-term reliability.
In summary:Pickling and passivation after welding are strongly recommended for Grade 2 titanium to restore and ensure optimal surface quality and corrosion resistance.
