Friction stir welding of lightweight materials

Abstract

The Welding Institute (TWI) of the United Kingdom invented Friction Stir Welding in 1991, which used a severe plastic deformation process to join low melting point alloys such as those of Al and Mg. Temperatures higher than the recrystallisation temperature but lower than the melting point are involved in this process. Microstructural changes in the deformed workpiece are observed as a result of the aforementioned hot working process, resulting in a change in the joint's final mechanical properties. The friction stir welding process is a solid state joining process that has gained popularity due to its ability to efficiently join low melting point low-density alloys such as Al and Mg alloys. Efforts were made to understand the change in microstructure of the Friction Stir Welded plates of AA 6061 T6 and AZ31B. For welding, parameters were fixed after a detailed literature review, a tool was designed and then manufactured. The welding was done as per the said parameters. Its microstructure was analyzed using an Inverted Optical Microscope, FESEM, EDS Analysis, XRD Analysis, and visual inspection of the weld.