Welding of titanium alloys: considering reactivity and cleanliness requirements, which welding process is most commonly selected in industry for producing high-quality joints in titanium and its alloys under an inert atmosphere?

Introduction:
Titanium and its alloys have excellent specific strength and corrosion resistance but are highly reactive at elevated temperatures. During welding, uncontrolled exposure to oxygen, nitrogen, or hydrogen can embrittle the joint. Selecting an appropriate process is crucial to ensure inert shielding and minimal contamination.

Given Data / Assumptions:

• We need a process that provides high-purity shielding gas and precise heat input control.
• Titanium requires stringent shielding on the weld pool, heat-affected zone, and sometimes the backside (trailing shields, backing gas).
• Target is reliable, production-worthy joints.

Concept / Approach:
TIG (GTAW) welding uses an inert gas (typically high-purity argon or helium) and a non-consumable tungsten electrode, offering excellent control over heat input and arc stability. It allows superior shielding and is the go-to method for many titanium applications. Electron beam welding, while excellent in vacuum with outstanding cleanliness and penetration, is specialized and capital-intensive; TIG remains the mainstream shop-floor choice.

Step-by-Step Solution:
Identify titanium's sensitivity to contamination at high temperature.Match welding processes to inert shielding capability and control.Select TIG (GTAW) as the common, practical choice for titanium.

Verification / Alternative check:
Fabrication standards and aerospace practices list TIG (often with trailing shields) as the primary process for thin to moderate titanium sections; EB welding is used for precision components in vacuum chambers.

Why Other Options Are Wrong:

• Submerged arc welding: Uses flux; not suitable for reactive titanium due to contamination risk.
• Butt welding: Refers to joint configuration, not a specific process.
• Electron beam welding: Technically suitable but not the most commonly selected day-to-day process; specialized equipment required.
• Oxy-acetylene: Oxygen presence and flame chemistry risk severe contamination.

Common Pitfalls:
Insufficient shielding of the weld root and trailing area leads to discoloration and embrittlement. Always use backing gas and trailing shields when welding titanium.

Final Answer:
TIG welding