Research Onthe Flow Field Of Bobbin Tool Friction Stir Welding Based On Tracer Meterial

Bobbin tool friction stir welding flow experiments were done based on copper powder as a tracer material in 6061 aluminium alloy, contrasted the location and characteristics of distribution of copper powder which if have done the experiment or not, the regular of flow byBTFSW and the impact to flow with different welding parameterswere investigated, the influence of the welding process were presented with the test results of plastic material in test plate motion model of horizontal direction and the thickness direction, and used the FLUENT software for BTFSW flow field in the simulation.Flow field test showed that the plastic material flow presents four different phaseson the advancing side of the weld in the horizontal direction, most of material moved to the reverse welding direction, only the materials in TMAZ moved to the welding direction.The plastic material moved to the reverse direction of welding on the retreating side, the materials in nugget zone have taken place in a secondary welding direction migration process.Material thickness direction, the thickness of the weld center under the action of the stirring needle thread line outward movement,the material in nugget zone either advancing side or retreating side have threaded from the top and bottom surface to the weld center movement trend, the material trend intensifiedon the advancing side but trend both to the thickness of the weld center and the weld surface.Plastic material motion model show that the displacement of tracer materialwhen out of toolwere depending on the obtain energy with the rotating friction of the contact time with the tool.The flow of materials presented different characteristicsbut the total flow had not changed with different welding parameters. Welding speed and rotating speed ratio of reduction is conducive to the flow which in horizontal direction and the thickness direction of hybrid will be intensified, the distortion of the length of the tracer material with welding speed and the rotation speed ratio decreases with increasing, but the welding speed of tracer material along the reverse direction of welding a maximum distance of almost no impact.Simulation results showed that the plastic material flow highest in mixing pin boundary and then lower in the shoulder diameter range. In the welding process, with the rotation of the material forward, within the scope of shoulder after metal than stir stir needle in front of the metal flow more easily, material near the mixing head of symmetrical horizontal velocity field at the center of the weld seam thickness. Welding speed and increasing rotating speed, the same increase in the number of materials involved in rotation,rotation speed increases welding speed, the same participate in rotary material decreases.