Here is what came back from the engineers:
We have no experience laser welding. We have had some
customers try with limited success. It is a “hot” process. Must
be tough to “cover”. As you know, we TIG weld. That said - the
blue and black are both most likely oxcides. Argon (or better
yet; an Ar and He mix) flow should be low enough to allow
filling of the cover area… Bottom coverage is, of course,
just as important. Feeding the shield - Ar from the top; if He
from the bottom. Maintain gas flow well after the work is
complete.
Bill Seeley
Reactive Metals Studio, Inc
@Bill_Seeley1
V-928/634-3434
F-928/634-6734