Aluminum Weldment Stress Relief

[atlarson]

What is the proper temperature for stress relief of a 6061 aluminum weldment? I have an internal company reference that lists 625-675 degrees F for 4 hours, but one of our suppliers told me they typically hold for 2 hours at 375 deg F. What would the difference be in final material strength, and stability during machining between these two processes?

Thanks in advance

 

[swall]

What was the condition of the 6061 prior to welding? Was it T6 or some other temper?

 

[atlarson]

T6.

 

[swall]

The 625-675F for 4 hours will pretty much destroy your T6 properties. You may be able to live with the mech properties with the 375F for two hours, but I wouldn't want able to a guess as to how much they would be reduced. Most T6 treatments for 6061 are in the range of 320-350F for 8-18 hours. You might want to machine up a tensile test bar from 6061-T6 after the 357F stress relief to see where you're at.