6061 weld failure

Date 10-30-2009 19:27 Edited 10-31-2009 18:26

good afternoon sirs
question welded Flanges on Aluminum tubes 5.25 od 1/8 wall using 5356
.045 filler wire ac at 140 to 180 amps argon 15cfh helium 10cfh
evrything was cleaned tube flange and filler rod with alcohol sst wire brush washed
of with alcohol and let them air dried no compressed air
the weld prep was 30 degree 60 degree combined bevel X .05 depth +.025 penetration
per customers drawings
tubes were leaked checked with helium leak detector to 1X10-9
sent out for heat treating
tubes were machined and leaked checked again no leaks
customer gets them they leak
question
would 550 for 3 hrs then air cool be enough heat to crack the welds
apreciate your coments thanks
gonzo

By Joseph P. Kane (****)

Date 10-30-2009 21:50

Gonzo

You do not say what the service application is, although you mention High Torr Helium leak detection. I cannot get a "minds eye" view of the joint detail from your description. Joint geometry and cooling rate could have significant impact on joint condition following PWHT at those temperatures.

Just the AC weld alone would cause leaks on high Torr welded components. I would recommend DCSP welding withn100% Helium and at least two passes, even though the tube is only 1.8 inch thick. DCSP welds are much denser than AC welds for High Torr applications.

I would also recommend magnified visual inspection of the weld termination for crater cracks.

Joe Kane

By gonzo

Date 10-31-2009 18:04

thank you for replay Mr Kane
the tubes are under Vacuum they just have to get tested to those specs .They dont see
any temp changes ,they are used for targets in solar panel coatting applications
I'm looking for the paper work that shows the heat treating temp they were put trough
if they used the 550 for 3 hours and air cooled out of the oven would this cause the welds to fail ?
if the welds were to small from the machining or it was just the wrong heat treating process ?
the weld prep in the drawing is 30 degree bevel x .050 deep on the tube and on the flange
I'll email a sketch of weld prep
I'll try to repair them with dc and helium
once again thank you
Gonzo

By Tommyjoking (****)

Date 11-02-2009 06:35

just wanted to let yall know

THIS SAME QUESTION IS BEING WORKED AT: http://www.aws.org/cgi-bin/mwf/topic_show.pl?tid=23052