Alu Extrusion Welds

[stresscalcs]

In the process of producing a hollow shape as an extrusion, when the extrusion is not specified as seamless, extrusion weld(s)(seams) are formed somewhere around the cross section.
The idea that two (or more) free edges of material flow together to form a continuous material section leads to the thought "is there a reduction of material strength properties at the seam?".

The extrusion is used in Aircraft secondary structure.

So far we have come up virtually blank on such information.
All we have found suggests there is virtually no strength reduction for good quality extrusions.
Can anybody say if there are any standards which cover this area or some possible information sources.

For anybody who has anything to say on the subject I would be most gratefull.

 

[metengr]

stresscalcs;
The following article might be of help. It appears that an evaluation was conducted of large hollow extrusions for a marine application;

http://www.azom.com/details.asp?ArticleID=153

 

[TVP]

The June 2004 issue of Light Metal Age had a good article on this subject. The author, L. Donati from Bologna University/Compes SpA (Italian aluminum extruder), is working on FEM simulation of extrusion welding. He references several different criteria that others have published for determination of acceptable extrusion weld quality. You can obtain more information by using the following link:

http://www.lightmetalage.com/