Friction Stir Welding of Al Alloy Thin Plate by Rotational Tool without Pin

Liguo Zhang1,3), Shude Ji1), Guohong Luan2), Chunlin Dong2) and Li Fu4) 1) School of Aerospace Engineering, Shenyang Aerospace University, Shenyang 110136, China 2) China FSW Center, Beijing 100024, China 3) Shenyang Aircraft Design & Research Institute, Shenyang 110035, China 4) State Key Laboratory for Manufacturing Systems Engineering, Xi an Jiaotong University, Xi an 710049, China

摘 要：For friction stir welding （FSW）, a new idea is put forward in this paper to weld the thin plate of Al alloy by using the rotational tool without pin. The experiments of FSW are carried out by using the tools with inner-concave-flute shoulder, concentric-circles-flute shoulder and three-spiral-flute shoulder, respectively. The experimental results show that the grain size in weld nugget zone attained by the tool with three-spiral-flute shoulder is nearly the same while the grain sizes decrease with the decrease of welding velocity. The displacement of material flow in the heat-mechanical affected zone by the tool with three-spiral-flute shoulder is much larger than that by the tool with inner-concave-flute shoulder or concentric-circles-flute shoulder. The above-mentioned results are verified by numerical simulation. For the tool with three-spiral-flute shoulder, the tensile strength of FSW joint increases with the decrease of welding velocity while the value of tensile strength attained by the welding velocity of 20 mm/min and the rotation speed of 1800 r/min is about 398 MPa, which is 80% more than that of parent mental tensile strength. Those verify that the tool with three-spiral-flute shoulder can be used to join the thin plate of Al alloy.

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