TWI

Models to predict the precipitate and grain size evolution in AA7449 aluminium alloy friction stir welds are presented and compared with experimental data. Bead on plate welds on 3.2 mm thickness sheets of composition Al, 8.4%Zn, 2.1%Mg, 1.8%Cu were performed using the GKSS FlexiStir system. Grain sizes of the welded material was determined and information about particle parameters was captured in-situ using small-angle x-ray scattering (SAXS). The precipitate evolution model was augmented with a model to predict grain size in the weld nugget. This model assumes that geometric dynamic recrystallisation (GDRX) is the dominant mechanism. Predictions of the combined precipitation and grain size model were compared to experimental data from SAXS measurements of the particle volume fraction and size evolution ahead of the tool.

8th International Symposium, 18-20 May 2010, Session 4B: Metallurgy, Paper 02