2" 6061 sch 80 6G test with pulsed MIG

admin

Gentlemen,Please help. We are working on two procedures: 6061-5086 and 6061-6061, both 2" SCH 80 6G, pulsed MIG. We are meeting radiography and bend test, but failing tensile. We are using 100% argon, about 147-164 amps, 20 volts, 3/64" 5356 wire. We are trying to keep the temp down below 250 F, but maybe this is an issue. Any help or suggestions greatly appreciated.Mike
Reply:why 100% argon?Vantage 500's LN-25's, VI-400's, cobramatics, Miller migs, synch 350 LX, Powcon inverters, XMT's, 250 Ton Acurrpress 12' brake, 1/4" 10' Atlantic shear,Koikie plasma table W/ esab plasmas. marvel & hyd-mech saws, pirrana & metal muncher punches.
Reply:Please describe what's happening when you fail the tensile test.  Is it a failure in the weld, HAZ, base metal?  Is it a ductile or brittle failure?  Is the test OK, but the yield or tensile strength is too low?  What code are you working with for these procedures?A picture of the failed tensile specimen might help us offer some advice.Benson's Mobile Welding - Dayton, OH metro area - AWS Certified Welding Inspector
Reply:because he weld aluminum
Reply:Its 6061 aluminum.  We looked at adding helium gas, but its a bit expensive.  The engineering company said most of their customers have switched back to straight argon because it costs less.  The inspector mentioned it failed at the weld.  The 6061 to 6061 coupon was almost there.  One coupon passed at over 25KSI but the other was a bit low at 21KSI.  The 5086 to 6061 coupons were 23KSI and 18KSI.   Both tests have 24KSI requirements.  Testing and welding procedure is to AWS D1.2.  Our 8" sch 80 passed.  Our guess is on the heat input and trying to minimize that.  We submitted two more coupons with faster travel speed and a fan blowing on it after each weld to cool it off faster.
Reply:Just got a call from testing company.  This time they didn't pass radiography.
Reply:Is the 5356 wire required?"If you live in Sacramento you have seen my work."
Reply:The 5356 has higher strength ratings and this is for a lift rated product to DNV 2.7-3 standard.  On the last coupons submitted we lowered amps, widened the root gap, doubled travel speed, and kept the interpass temp below 200.  I'll post the parameters in the morning for comparison.  Our next attempt we are thinking of going back to 1/8" gap, turning the heat back up some, and keeping the travel speed same as last test.