Abstract
Tin plated 6061-T6 Al extrusions were friction stir welded in a 90° butt weld configuration. A banded microstructure of interleaved layers of particle rich and particle poor material comprised the weld nugget. Transmission electron microscopy revealed the strong presence of tin within the particle rich bands, but TEM foils taken from other microstructural regions showed no indication of Sn containing phases. Since tin is limited to the surface of the preweld extrusions, surface material flowed into the nugget region to form the particle rich bands, while the particle poor bands originated from material within the extrusion thickness. The morphology of the principle strengthening phases indicated the relative temperature profile across the welded joint, and hardness profiles of as welded specimens consistently displayed the lowest hardness on the retreating side. Specimens that were solution heat treated and aged after welding revealed a normalised hardness profile across the weld.
Get full access to this article
View all access options for this article.