Hello Happywelder!
A google, yahoo, msn, etc. search will give you a broad perspective regarding titanium and it's applications, and advantages when compared to other metals...
Try this website for size: http://www.azom.com/Details.asp?ArticleID=1245
This one not too bad:http://www.astm.org/cgi-bin/SoftCart.exe/DATABASE.CART/REDLINE_PAGES/B363.html?L+mystore+subi4996
This Website is a pretty good one especially for your PWHT question also: http://www.titanium.com/tech_manual/tech4.cfm
Heres one of the better ones: http://www.deutschetitan.de/eng/profi/kb11.html
Of course, you should have one of these gadgets:
http://www.read-tpt.com/featuredetail.asp?ID=173
I almost forgot about this one from the Hobart Institute of welding Technology: http://www.welding.org/newsletters/summer2002/titanium.html
These four should answer most if not all of your questions...
Of course there are other sites with great info also so, happy hunting, and I hope this helps!
Btw, I welded alot of Ti in New Jersey for Titanium Industries (now called Titanium Fabrication Corp.)...
Back then, we mostly used GTAW, and sometimes GTAW-P...
I believe the most important emphasis was on keeping everything super clean!!! We used lab grade gases because, we did'nt want to take any chances. Alot of the vessels we made were for the pulp/paper industries but, we also did work for a variety of of other industries also...
I personally welded anything from small diameter tubing to two inch thick Ti!!! Lots of prep work for back purging though...
Make sure your trailing shield is working properly also!!!
The US Navy is replacing alot of their copper-nickel piping with Ti, and on the newer ships their using Ti instead...
Lawrence Livemore's Ti experiments in realtime via the use of a synchrotron is a definite stop in your Ti info journey: http://www-cms.llnl.gov/s-t/welding.html
I saved the best for last!!! Titanium Information Group/TWI Best practices Guide "Welding Titanium-A Designers and Users Handbook"
in.pdf: http://www.obimatic.co.uk/Titanium%20Guide.pdf
Anywho, Good luck!!!
Respectfully,
SSBN727 Run Silent... Run Deep!!!
P.S. Remember the activated GTAW flux I was asking about?
Well, here's another interesting website which also includes Ti :
http://www.geocites.com/saidov_r/pros.htm
I hope this is sufficient for now... Oh yeah, Corrosion resistance gets better while ductility deteriorates with grade 2 Ti... Almost forgot!!!
I'm out of here!!!