Aluminum Diecast (A360) & Aluminum Extrusion (6061 T6)

[greencircle]

Not sure if this is a welding question. But I want to see if the material combination is correct. Is it possible (recommended ?) to weld Aluminum Diecast (A360) & Aluminum Extrusion (6061 T6)?
Even tough joint looks good, we noticed severe corrosion overtime.

On the first had I want to see if these 2 alloys are OK to be welded. I will try posting this question with welding perspective under the welding forum.

Thanks,
GC

 

[TVP]

Can you provide some additional information:

- What type of welding process was used (GMAW, GTAW, LBW, etc.)?
- Was filler metal used? If so, which alloy?
- Corrosion in what environment?

In general, high pressure die castings do not have very good corrosion resistance, and welds will be even worse. The porosity in the castings can produce large blisters or other surface defects in the weld zone, which can trap liquid, contaminants, etc. which further accelerate the corrosion rate.

 

[greencircle]

Parts were welded with a 1/4 in fillet using GMAW method
Yes, 4043 filler was used.
Although the welded assembly is powder coated, but are installed by a sea shore.

I can understand that there could be corrosion from the wind/mist from the sea, but could it influence more than the fact that these are dissimilar parts.
Could this weldment behave better if its not in the marine environment.

As per this chart i found about filler material, I beieve there isnt one filler material for the combination of base metals as 6061-T6 & 360

http://www.esabna.com/shared/documents/litdownloads/alc-10030c_alcotec_alloy_selection_brochure.pdf

So, I am kind of thinking if these are all together incorrect fusion.

Thanks,
GC

 

[metengr]

Please do not cross post with other forums
thread725-424362

 

[TVP]

I'm just getting back to reading this thread. High pressure die cast alloy 360 is NOT suitable for service near an ocean or other environment with continuous exposure to mist/spray/splash of saltwater. This alloy has very poor corrosion resistance. The pre-treatment for the coating will need to be optimized for aluminum and the coating must have sufficient thickness to provide anything more than months of service before cosmetic corrosion will occur. Crevice corrosion and exfoliation are also quite likely.