Abstract:

Stretch-forming of wide aluminum sheets is commonly used to produce parts such as leading edges and fuselage panels. Typically, this process uses very wide high surface quality sheets (sometimes "polished skin

sheets") that is cladded on both sides with a 1XXX series aluminum for corrosion resistance. Stretch forming operations for leading edges skins are typically performed in the transverse direction (perpendicular to the rolling direction). This process leads to a significant amount of expensive material that is wasted due to the fact that the stretching jaw marks are cut off upon completion of the stretch forming process.

A collaborative project between SONACA and Kaiser Aluminum identified Friction Stir Welding, FSW, as an enabling technology to reduce the total cost of the manufacturing process from ingot casting and rolling through to stretch forming and final part preparation. This lower cost manufacturing method uses FSW to attach non-clad (bare) aluminum "tabs"

on either side of a narrow polished skin sheet with cladding material on one side only. The bare aluminum "tabs" are placed inside of the stretcher jaws and the entire bare-clad-bare welded panel is stretch formed. Once the panel is formed the FSW regions and the bare aluminum "tabs" are removed producing a polished skin sheet part with cladding material on one side only. This paper will summarize the development of this lower cost process and the material properties and performance of the parts produced using this process.