Duplex Stailess Steel (DSS) Welding

Here is a fairly good web site on your questions on duplex stainless.

http://www.azom.com/details.asp?ArticleID=2870

Good luck to you

Get ready for that stuff to move around when you weld it and it cools. We had a project where we welded 8 inch DSS pipe with 3/4 inch walls (very high pressure) with 2-3 root passes with TIG and covers with SMA. You could watch a 4 foot long pipe crawl a inch or more side to side as a joint was welded. This was a major concern during pipe fit up and flange alignment. The welders did some heating tricks to crawl it back in shape although details are unknown to me.