3-Dimensional CFD modelling of flow round a threaded friction stir welding tool profile

Modelling of friction stir welding of DH36 steel

“…This, consequently, resulted in a smaller temperature distribution in the tool/workpiece depth and thus a smaller HAZ is expected. Colegrove and Shercliff [30] also reported the same effect; that changing the tool rotational speed has a more significant effect on the peak temperature than a change in traverse speeds and the HAZ decrease with the increase in traverse speed. Temperature contours of the longitudinal cross section of the tool for all cases studied shown in Fig.…”

“…The evidence of localised melting at the same advancing-trailing side has been reported in [28] and also in [29] for welding aluminium alloys. Colegrove and Shercliff [30] found that maximum temperature calculated from CFD modelling of aluminium at 90 mm/min and 500 RPM is exceeding the melting point. However, they suggested that in actual welds this temperature would be lower due to two reasons; firstly in the actual weld, slip between the tool and the workpiece can occur reducing the heat input and consequently avoiding melting.…”

A numerical comparison of the flow behaviour in Friction Stir Welding (FSW) using unworn and worn tool geometries

“…However, a numerical technique which has a predictive capability is perhaps more powerful, since it allows the process parameters to be efficiently optimized. Numerical studies of the flow behaviour in FSW have been presented in the literature since 1991; this body of work includes important studies that have examined the flow behaviour around different tool designs, carried out by Colegrove and Shercliff [8,9] and Ji et al [10].…”

“…This work described the flow of the metal through the use of streamlines and velocity vectors and predicted that workpiece material is swept from the advancing side to the retreating side of the pin, before flowing vertically down near the surface of the pin until it reaches the weld root and then it flows upwards towards the upper part of the workpiece behind the pin. While these models provided good insight in terms of material flow, the models of Colegrove and Shercliff [8,9] were limited to qualitative prediction of the size of the deformed zone based on a region provided by a limiting value of strain rate, which may be the reason for the over prediction of the deformed zone in these works. Another important point when considering the works of the Colegrove and Shercliff [8] and Ji et al [10] was that the contact interface between the material and the tool was only considered as a sticking condition, which may again lead to an over-prediction of the deformed zone due to the likely presence of slip on some areas of the tool.…”

“…The bulk of the literature concerning the numerical modelling of the FSW process has demonstrated over-prediction of the temperature, power input and the size of the Mechanical Affected Zone (MAZ) when comparing the results of simulations with experimental observations. The majority of these works argued that these differences were due to the stick condition (no-slip) assumed at the tool surface, which ensures that the workpiece material at this location rotates at the surface speed of the tool [8,13]. These studies concluded that using partial stickslip at the tool surface reduces the heat input and avoids material melting at the interface between tool and workpiece, and for this reason material deformation under the shoulder will reduce.…”