AWS D17.1: Tensile strength (minimum) of as-welded 6061-T6 Aluminum

[Weldman7]

I'm looking for a resource/specification that notes the minimum tensile strength of 6061-T6 aluminum in the as-welded condition should be that of 6061 in the annealed state, since 6061-T6 is known to drop in tensile strength in the weld and HAZ areas significantly following welding. Multiple tensile tests illustrate that values hover just above and below the minimum for 6061-T6, on very high quality welds that pass X-ray to a AWS D17.1, Class A level. This information is needed to assist in procedure qualifications to both AWS D17.1 and AWS D1.2. Additionally, we have experienced bend test failures on 6061-T6 weldments, right in the transition area between the HAZ and unaffected base metal, I believe due to the sharp change in formability from the weld centerline out caused by the welding heat input/annealing. Can anyone comment on this and how it might be addressed going forward?

 

[gtaw]

AWS B2.1, D1.2, and several other sources list the minimum ultimate tensile strength in the as welded condition as 24 ksi.

Aluminum alloys grouped as M23 and those welded with F23 filler metal must be tested using a bend mandrel much larger than that used for carbon steel. Typically the mandrel measures 2 1/16 inch in diameter for samples 1/8 inch thick. If test thicker material, the face or the root is typically reduced to 1/8 inch prior to bending. Use a wrap around bending fixture to eliminate the problem you mention, i.e., failure in the HAZ.

Best regards - Al