> In terms of fabrication, all welding of titanium must be done in an inert atmosphere of argon or helium in order to shield it from contamination with atmospheric gases such as oxygen, nitrogen, or hydrogen.[11] Contamination will cause a variety of conditions, such as embrittlement, which will reduce the integrity of the assembly welds and lead to joint failure. Commercially pure flat product (sheet, plate) can be formed readily, but processing must take into account the fact that the metal has a "memory" and tends to spring back. This is especially true of certain high-strength alloys.[48][49] Titanium cannot be soldered without first pre-plating it in a metal that is solderable.[50] The metal can be machined using the same equipment and via the same processes as stainless steel.[11]
https://en.wikipedia.org/wiki/Titanium#Production_and_fabric...
There are other issues as well; for example, I was reading _Dreamland_ and it mentioned that among the issues the SR-71 program ran into while working with titanium, was discovering that tap water could not be used with titanium-related processes because the chlorine would weaken the titanium or something.