We have to write up and qualify an AWS WPS for 1" 5086 alum plate groove weld(CJP) in horizontal position GMAW. Done 2 test plates (only transverse side bends) but both have unacceptable (>1/8") cracks. Most cracks are right at the base metal / weld metal interface.
Details: filler is 5356 1/16" wire, Argon at 75 cfh, multipass(26!) stringer beads, 5/8" contact tube to work piece, no peening, no pre or post heat, inital cleaning with acetone, interpass cleaning with wire brush, DCRP spray at 28V and 240 amps (root slightly higher), travel speed not recorded. Joint is single V butt joint 45/15 degrees groove, root face of 1/8", root opening of 1/4" with 3/8" thick backing plate (no back gouging). Interpass temperatures not recorded (now ordering some temp crayons).
Test coupons are 3/8" slices with edges smoothed with 1/8" radii and bent with wraparound guided bend jig with dia of 2-1/2".
Our welder can pass same test in flat position easily, but our design now requires certification in horizontal position. We will appreciate any help and suggestions. We also need some help understanding and applying pulse arc welding details pertaining to this test. Thanks