TY - JOUR A1 - Su, H. A1 - Wu, Chuan Song A1 - Bachmann, Marcel A1 - Rethmeier, Michael T1 - Numerical modeling for the effect of pin profiles on thermal and material flow characteristics in friction stir welding JF - Materials and design N2 - Understanding the influence of tool/pin shapes on the thermal and material flow behaviors in friction stir welding is of great significance for the optimal design of tool/pin based on a scientific principle. In this study, a numerical method based on computational fluid dynamics is employed to quantitatively analyze the thermo-physical phenomena in friction stir welding with two tools of different pin shapes (axisymmetrical conical tool and asymmetrical triflat tool). Through combining a steady state model with a transient state model, both the computation efficiency and accuracy are ensured. The boundary conditions of heat transfer and material flow are determined with considering a partial sticking/sliding contact condition at the tool–workpiece interface. The total heat generation, heat density and temperature distribution during the welding process with triflat tool are elucidated and compared with that of conical tool, and the material flow patterns and deformation regions of various pin orientations are illustrated in detail. It is found that the deformation zone caused by triflat tool is larger than that by conical tool, which is validated by the weld macrographs. The computed thermal cycles and peak temperature values at some locations are in good agreement with the experimentally measured ones. KW - Friction stir welding KW - Pin profile KW - Heat generation KW - Material flow KW - Modeling PY - 2015 DO - https://doi.org/10.1016/j.matdes.2015.04.012 SN - 0261-3069 SN - 0264-1275 VL - 77 SP - 114 EP - 125 PB - Elsevier Ltd. CY - Oxford AN - OPUS4-33031 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Zhang, X. A1 - Shi, L. A1 - Wu, C. A1 - Yang, Chunliang A1 - Gao, S. T1 - Multi-phase modelling of heat and mass transfer during Ti/Al dissimilar friction stir welding process JF - Journal of Manufacturing Processes N2 - Friction stir welding (FSW) has the capacity to join the Al/Ti dissimilar structures with superior mechanical properties. The microstructures and mechanical characteristics of Al/Ti dissimilar FSW joints are determined by the heat and mass transfer during the welding process. However, a quantitative study of the Al/Ti dissimilar FSW process is lacking. Therefore, using the computational fluid dynamics (CFD) and volume of fluid (VOF) approach, a multi-phase model was constructed for quantitatively analyzing the heat and mass transfer behaviour in dissimilar FSW of TC4 titanium alloy and AA2024-T4 aluminium alloy. The mixed material was treated as a functionally graded material (FGM) to compute the thermophysical characteristics at the weld nugget zone (WNZ). Due to the vast disparity in the thermophysical characteristics of aluminum and titanium alloy, the temperature field in Al/Ti dissimilar FSW was severely asymmetric. The temperature of titanium alloy on the advancing side (AS) was higher than that of aluminium alloy on the retreating side (RS) at the same distance from the tool centre line near the tool shoulder, but it was lower than that of aluminium alloy on the RS without the influence of the shoulder. Due to the high flow stress of titanium alloy, plastic material flow mostly occurred on the RS of aluminium alloy in the Al/Ti dissimilar FSW, with its percentage exceeding 80%. This model was validated by experiment results. KW - Dissimilar friction stir welding KW - Al/Ti dissimilar joints KW - Temperature distribution KW - Heat generation KW - Plastic material flow PY - 2023 DO - https://doi.org/10.1016/j.jmapro.2023.03.037 SN - 2212-4616 VL - 94 SP - 240 EP - 254 PB - Elsevier Ltd. AN - OPUS4-57265 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -