welding of al 6061 2

[mjem27]

I have to weld to parts made from AL 6061(1mm thick).
I consider two options: heat treat to T62 condition and then welding OR heat treat to T42 condition-welding-heat treat to final condition T62.
Pls your advise.

 

[gtaw]

In the as welded condition, UTS of 24 ksi is considered to be acceptable per AWS D1.2 and ASME Section IX.

Use interpass cooling to reduce the effects of over aging the aluminum. The short version of the story is that you want to minimize the time at temperature to maximize your mechanical properties in the as welded condition. Do not preheat the aluminum. If you are having difficulty obtaining good fusion, you need more "heat" by switching to helium rich shielding gas and increase the wire feed speed (amperage), but do not preheat the aluminum.

You will have better results with GMAW in the spray transfer mode. Use large diameter electrode to reduce the number of weld beads needed to fill the groove. The groove angle should be increased over what would be used with carbon steel. 75 degrees is the minimum I would recommend. Cool the aluminum between weld beads to reduce the time at temperature.

You can weld the aluminum using GTAW with helium shielding gas, but you will not get cathodic cleaning, so you have to be fastidious with your cleaning before and during welding.

Clean, clean, and clean it again before welding. Use a clean stainless steel scratch brush to remove surface oxides just prior to welding. Use the brush as you would a hacksaw, i.e., push the brush in one direction, toward the groove, and lift the brush on the back stroke.

Do not use an aluminum oxide wheel or abrasives to prepare the joint or to preclean the joint.

Do not use waxes and remove all oil, including finger prints, using virgin acetone followed by a rinse with 90% isopropyl alcohol.

Good luck.


Best regards - Al