C. X. Zhao, I. M. Richardson, Materials Innovation Institute/Delft University of Technology, Delft, Netherlands; V. V. Steijn, Z. S. Saldi, C. Kleijn, Delft University of Technology, Delft, Netherlands
In order to explore the physical mechanisms governing weld pool fluid flow, measurement of flow behaviour on the surface of a weld pool can be undertaken. To date, most of the reported experimental results evaluate the surface flow by tracing single particles, not the whole surface flow field. In this report, we calculated the whole surface flow field for a GTAW weld pool by studying the movement of the natural oxide layer on a 316L stainless steel substrate. The surface flow field is reconstructed based on a high-speed camera imaging, and particle image velocimetry (PIV) to calculate the surface flow velocity. An unsteady flow field was captured, which contains strong rotational flow on the weld pool surface.
The Reynolds number was calculated to analyse the flow motion to determine whether the flow in the weld pool is laminar or turbulent. The maximum velocity based on a theoretical analysis is compared with our experimental results. We also describe the relationship between the maximum velocity and the weld pool shape.
Finally, an analysis of error sources is made for the computed weld pool surface flow velocities and some suggests are provided to reduce the error in the two dimensional surface flow field.
Summary: A experimental method for acquiring the surface velocity field of the weld pool was reported in this paper, which provides experimental results to understand how fluid flow on the weld pool surface.
