409SS weld then forming problems

Weld seam cracks after roll forming a flange.

Process: Rolling a cylindrical tank with 14 ga 409SS sheet and
using SAW for the butt weld seam. Filler is ER309LSI and flux is
ST-100. After the seam weld, a .4" deep flange (rough cross
section below) is roll formed on the top edge of the tank. The
weld is so brittle it cracks at the stressed corners. I am getting
mixed info on pre- and post-weld heating. One says to use low
heat input during welding and form at room temp without
annealing. Another expert suggested pre- and post-weld
treatment. If heat treatment is recommended, can heating with a
dull grinder be effective? Any other suggestions? It would be
nice if a ductile filler for 409 and 304 could be found. Thanks in
advance. SCOTT

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[jcrowe]

The welding process and filler selection will somewhat alleviate your problem, but I'd say offhand that you will get best, quick results from annealing the weld affected zone prior to forming. You are losing all the ductility in the heat affected zone from the welding.

 

[tedg]

Would suggest you visit

http://www.nidi.org

and look through the technical info you can download there. Among several items on welding of stainless steel, I recall # 10,014, #1208 and #9002. You may find others by using the search engine available on the NiDI site. Good luck.

 

[gilley29]

Thanks for the NIDI source - doc 9002 has some good SS info.