heat treating welded 356

[BobM3]

I need to weld a plate to a 356-T6 aluminum housing. I'm thinking a 6061 plate. What sort of heat treating should be done after welding to get the casting back to the T6 condition?

 

[Goahead]

The tricky part of heat treating aluminum alloys is, besides very exacting temperature control, the need to quench very rapidly. Another problem may be distortion, depending on general shape of the parts and their thicknesses.

Could you think of mechanical joining?

http://www.welding-advisers.com/

 

[BobM3]

Distortion would be a problem because there's some machining already done on the casting that can't be allowed to move too much. Strengthwise, it sounds like I'd have to heat and quench and age to get back the T6 strength?

 

[swall]

If you can get past the distortion issues, the T6 re-heat treat should not be a problem, although you will need to locate a competent aluminum heat treater. Two comments--In my experience, you can cut the solution heat treat time in half when the previous condition was T6 and welding was performed on the casting. We used to repair weld 355-T6 castings and used a 4 hour solution time. Second--the solution treatment temp of 6061 is about 15 degrees lower than that of 356, and it would be advisable to use that lower temp to avoid any chance of eutectic melting of the 6061.