pull test issue while qualifying aluminum welds as per AWS 1

[pparent]

We want to qualify some plug welds on aluminum plates (5052 H52). When we weld samples plates and we test them like we do on other steel and stainless steel qualifications, we get values in aluminum excessively low!

We weld 2x 1/8 thick x 1" wide alum. sheet. One has a hole (.25 dia.) and we fill it like usual with a plug weld. When we pull on it on our testing machine, we get very Forces. Are weld resistance calculations for qualifications different than in steel parts?

PP

 

[gtaw]

Many aluminum alloys loose strenght when welded. AWS D1.2, AWS B2.1, and ASME Section IX are in good agreement on the required tensile strengh after welding.

Some military welding standards require the completed weld to have the same tensile strenght as the unwelded base metal. That pretty well eliminates a number of aluminum alloys from being used for military applications.

You also have to compare the tensile strength of the filler metal and combination of filler metal diluted with base metal to that of the base metal alone.

You didn't reference a welding standard, so I can't give you any specific direction.

Best regards - Al

 

[Ron]

pparent...the heat affected zone in aluminum is quite large and the effect of welding is usually lower allowable stresses because of the difference in tempering that occurs in the weld area.

Based on published mechanical properties, 5052-H32 in an unwelded condition has a tensile yield strength of 23ksi whereas 5052-H32 welded has a tensile yield strength of 13ksi. Run those numbers on your weld area and you'll probably see your answer.

check in the Aluminum Association Design Manual for additional info.