Effect of welding tool geometry on microstructure and hardness in Friction Stir Welded Plates

Friction Stir Welding is a solid state welding process for joining aluminum and other
metallic alloys where the metal is not melted during the process and the original metal
characteristic remains unchanged as far as possible. It was invented in 1991 in The
Welding Institute (TWI), United Kingdom to substitute conventional welding of
aluminum alloy. Friction Stir Welding can be use in shipbuilding marine, aerospace
industry and railway industries. The welding parameters and tool pin profile play a
major role in defining the weld quality. This report covers the theoretical background
of friction stir welding, literature reviews on related research works, implemented
methodology, and current results. The objective of the project is to study the effect of
welding tool geometry on the microstructure and hardness of welded plates. The
project will focus on three types of pin design which are straight cylindrical, threaded
cylindrical and tapered. The tools are fabricated using CNC Machine and undergo
heat treatment. Two plates of aluminum alloy work piece were set-up in butt joint
configuration and clamped rigidly during welding operation. The work pieces are
welded using different type of welding tool pin profile and different sets of
parameters. Welded work pieces that have been welded by the designed tools were
undergo lab testing which are hardness and microstructure test in order to rectify the
difference of the weld results. From this project, it can be observed that different
geometry of tool will produce different weld results