What precaution must be taken when welding titanium?

The correct response emphasizes the critical importance of minimizing the presence of oxygen and nitrogen during the welding of titanium. Titanium is highly reactive, especially when exposed to elevated temperatures that occur during welding. Oxygen and nitrogen can lead to embrittlement of the weld metal, adversely affecting the mechanical properties and integrity of the material. Therefore, an inert gas shielding, typically argon, is utilized to create a protective atmosphere around the weld area, ensuring that these harmful gases are effectively excluded. By doing so, you maintain the titanium's desirable characteristics, reducing the risk of contamination and ensuring a high-quality weld.

The other options, while relevant to welding practices in general, do not specifically address the unique challenges posed by titanium welding. Proper ventilation is important in many welding applications for safety considerations, but it does not directly mitigate the issues associated with oxygen and nitrogen. Limiting the use of torch flame can be a good practice, but it isn't sufficient in itself when welding titanium since the reactivity concerns remain unaddressed. Similarly, adjusting welding speed might influence the heat input but doesn’t solve the problem of gas exposure that is crucial for titanium.