Design And Experimental Research Of Special Tool For Friction Stir Welding

Friction Stir Welding(FSW),as a solid-phase welding technology,has a unique advantage in welding low melting point materials.And it has been successfully applied to the joining of aluminum alloy.However,there are still many problems in joining of dissimilar materials and high melting point materials,among which the design of tool is a relatively prominent problem.In order to expand the application range of FSW technology,the design of tool and related experimental research were carried out in this paper.In this study,H13 hot work die steels and W-25 Re alloy were used as raw materials,and the design of tool was carried out for different weldments.The tool structural design includes integral and split type.In this study,tool was designed for different materials.The tool was made of H13 hot work die steel and W-25 Re alloy.The bearing capacity mathematical model of tool was established and the specific size of each part of the tool was designed accordingly.The results of show that friction stir welding of 2219 aluminum alloy could be realized when the tool was almost lossless by using the integral tool.The tensile strength of the joint was 337 MPa and the elongation was 8.1%.However,the wear of the integral tool was serious when the aluminum copper dissimilar materials were welded.The pin was adhered,which leads to the defects of groove and kissing bond.Therefore,the welding of 6082 aluminum alloy and T2 copper dissimilar material was realized by using the split tool.After welding,the tensile strength of FSW joint reached 237 MPa and elongation was 6.2%.Finally,T2 copper was welded with the split tool,and the FSW joint with the tensile strength of 255 MPa and the elongation of 8.3% was obtained.About the tensile test results,it could be found that the tensile strength of the aluminum copper dissimilar alloy FSW joint increased gradually with welding speed,and then decreased rapidly after reaching the maximum value.The same rule with rotating speed has been observed in the welding of T2 copper.Therefore,the selection of welding parameters would directly affect the mechanical properties of the joint.In conclusion,the tool made of H13 hot work die steel could accomplished the friction stir welding of aluminum alloy.But for aluminum-copper dissimilar materials and high melting point materials such as copper alloy,the material of tool needs better wear resistance and high temperature resistance.The W-25 Re alloy selected in this paper could be used as a reference.The effects of welding speed and rotation speed on the mechanical properties of the joint were also studied in this paper.It can be concluded that the design of tool would determine the application field of FSW,and the selection welding parameters would directly determine the quality of welding joint.