A Three-Dimensional Model for the Friction-Stir Welding Process

摘要

Friction stir welding (FSW) is an emerging solid-state joining process. Joining is achieved through a mixing and extrusion action of a rotating pin-shoulder tool that moves between two parts being joined The advantages of FSW over traditional fusion welding techniques include (a) there is no melting in the process and hence there are no melting-related joint imperfections, (b) the joint has a high mechanical efficiency, and (c) it can be applied to many "hard-to-weld" alloys (e.g. aluminum alloys). Currently FSW is still in its early development stage and a predictive scientific knowledge based has not been established. The work presented here is based on a three-dimensional model of the FSW process and is intended to capture some of the main thermo-mechanical features occurring in the process. This model is developed based on several advanced options in a general-purpose finite element code and on limited experimental data available so far. In particular, an Arbitrary Eulerian-Lagrangian finite element formulation with adaptive meshing is utilized, which considers large elastic-plastic deformation and temperature-dependent material properties. It appears that there is a good correlation between the equivalent plastic strain distribution and the microstructure zones in the weld.