Effect of Different Welding Tool Pin Shapes on Friction Stir Welding Plates Microstructure

Friction Stir Welding (FSW) is a method to join solid-state metal plates. This teclmi.que
was started in 1991 and since then, many studies and research have been done in order.
to improve this method. People are really interested in this technique because they
realized this technique has more advantages and have many potential for improvement.
In this project, the effect of different tool pin geometry on the welding plat<;'s
microstructure will be investigated. Three different geometry tools pin, round, square,
and triangular will be used to fabricate the joints. After that, the formations of friction
stir plate's microstructural zone will be analyzed. There are several parameters that will
effects the formation of the microstrutural zone. In this project, since our main purpose
is to study the effect of tool pin profiles on the microstructure of friction stir weldinK
plates, others parameter such as tool rotational speed, and welding speed, and axial force
are constant. It is found that rectangular tools (Sample 5) have the best microstructure
quality out of all three tools. Sample 5 shown smallest grain size. Smaller grain size is
preferable because it result in more grain boundaries that strengthen the material. Grain
boundaries increase the strength of aluminum by resisting the movement of dislocations
in the microstructure. Therefore, more force is required to deform a material when it has
large quantity of grain boundaries. In FSW, a good weld quality could be defined base
on the strength of the joint To fulfill the desired strength, proper welding parameters
should be selected.