Microstructure, corrosion and environmental cracking behavior of friction stir welded cast aluminum 7050 ingots alloyed with scandium additions was investigated. An over-aged (T7451) and a homogenization (24 h/475 °C) temper were applied to the as-cast plates before friction stir welding, while a post-weld heat treatment was applied to all welds to verify the changes in the corrosion behavior. It was found that the as-cast and heat treated friction stir weld samples exhibited a fully recrystallized equiaxed grain microstructure. The scandium did not significantly dissolve in any of the phases present and remained homogeneously distributed within the matrix. The as-cast friction stir weld microstructure exhibited apart from the nugget region coarse grain boundary phases, wide precipitate-free zones and coarse intragranular precipitates. The post-weld heat treatment (1 h/480 °C-1 h/100 °C boiling water and quench) increased the tensile strength of the as-cast weld, but decreased the strength of the heat treated welds. The heat treatment of the as-cast samples to an overaging (T7451) and homogenization (24 h/475 °C) temper increased the general corrosion susceptibility of the friction stir welds.
|Number of pages||9|
|Journal||Materials Science and Engineering A|
|State||Published - May 25 2006|
Bibliographical noteFunding Information:
The authors would like to thank the Materials and Manufacturing Directorate, AFRL, for the financial support, Mr. Ken Davidson program manager. R. Perez of the Boeing Company for providing the material and A.P. Reynolds, University of South Carolina for the welding.
- As-cast microstructure
- Environmental assisted cracking
ASJC Scopus subject areas
- Materials Science (all)
- Condensed Matter Physics
- Mechanics of Materials
- Mechanical Engineering