6061 welded with 5556

[mattyf2]

We are having problems with welds cracking. We are welding 6061 T651 1/2" thick with 1/16th" 5556 filler using the GMAW process anyone have any input on why and possible prevention we are keeping the temp below the 250 degrees f. The weld sizes range from 1/4" to 3/8" fillets. We are tring to weld the 3/8" weld in one pass any suggestion would be great.

 

[berkshire]

Mattyf2,
See if this helps.
B.E.

You are judged not by what you know, but by what you can do.

 

[mattyf2]

Thank you, it seems all the info I found is about the same any other ideas.

 

[metengr]

Why are you using 5556? For 6061, you need to use either 4043, 5356 or 5554.

 

[mattyf2]

That is what the engineer is requesting the aluminum code book says it is an acceptable replacement for 4043. If it was my choice I'd be welding it with 4043.

 

[berkshire]

Mattyf2,
If you are not heat treating or anodizing, 5356 is a far more user friendly alloy.
5556 does give the highest strength in the weld, but it is also the alloy that is most prone to cracking.
Even 5356 will give you some cracking problems if you cool the weld too quickly.
Are you using pulse, or are you going straight current with taper up, taper down/crater out?
B.E.

You are judged not by what you know, but by what you can do.