[TheForge] Aluminum welding

[John Allen]

I welded an aluminum dump truck dump body frame rail together since a
4 foot section had to be replaced at the pivot end. I replaced the 6
inch I beam with a new one and I welded it together. The owner has
contacted me that the weld broke. I fixed it and gave it back. He now
said it did it again. It is breaking from the top of the beam down.

I made straight cuts and there was about a 3/8 inch between the old
one and the new piece. I mig welded the outside after I cleaned the
joint with a brand new stainless steel wire wheel and then aluminum
cleaner, muradic acid. I welded it at proper settings and helium gas.
I even cross stitched weld over the vertical weld to improve strength.
I am using 4043 3/64 wire

After it broke the first time, I asked other welders what I did wrong,
they don't know. I am loosing my mind trying to figure it what I am
doing wrong. I do not have a welder heavy enough to put out 250 amps
to tig weld it but I do have a 302 trailblazer that I could run 225
amps to tig it. I don't know what to do besides replacing the entire
beam and eliminate the weld.

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