A model of material flow during friction stir welding

作者：Hamilton Carter^*; Dymek Stanislaw; Blicharski Marek

来源：Materials Characterization, 2008, 59(9): 1206-1214.

DOI：10.1016/j.matchar.2007.10.002

• friction stir welding
• aluminum
• microstructure
• weld nugget
• material flow

Tin plated 6061-T6 aluminum 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. Scanning and transmission electron microscopy revealed the strong presence of tin within the particle-rich bands, but TEM foils taken from the TMAZ, HAZ and base material showed no indication of Sn-containing phases. Since tin is limited to the surface of the pre-weld extrusions, surface material flowed into the nugget region, forming the particle-rich bands. Similarly, the particle-poor bands with no tin originated from within the thickness of the extrusions. A model of material flow during friction stir welding is proposed for which the weld nugget forms as surface material extrudes from the retreating side into a plasticized zone surrounding the FSW pin. The extruded column buckles between the extrusion force driving the material into the zone and the drag force of the in-situ material resisting its entry. A banded microstructure of interleaved surface material and in-situ material, therefore, develops. The model successfully describes several of the experimentally observed weld characteristics, but the model is limited to specific conditions of material flow and assumptions regarding steady-state.

• 出版日期2008-9