Effects of friction stir welding on corrosion and mechanical properties of AA6063 in sea water

Abstract

Submerged friction stir welding (FSW) is used to improve the weld zones mechanical properties in the present study. This research aims to obtain the optimized process parameters used to fabricate the AA6063 Submerged FSW joint. In the Submerged FSW process, the most important influential factors are tool rotational speed, traverse speed, and pin profile in a seawater environment. The different workpieces are friction stir welded while submerged in seawater at different tool rotational speeds, traverse speeds, and tool pin profiles such as square pin, cylindrical taper pin, and threaded pin. The produced weldments were tested for the mechanical properties of higher tensile strength, microhardness, corrosion rate, and the microstructure of weldments was characterized by using a scanning electron microscope, transmission electron microscope, and X-ray diffractometer. The corrosion rate is investigated by using an electrochemical analyzer by potential dynamic polarization open-circuit technique. For this investigation, The Taguchi method with the L9 orthogonal array design of experimentation is adopted. The maximum UTS was acquired in the weld joint fabricated with 1250 r/min of tool rotational speed, 45 mm/min traverse speed, and a square tool pin. The stirred zone is tested for microhardness. High hardness is achieved with high tool rotational speed and low traverse speed with a square tool pin profile. The corrosion rate is also decreased with high tool rotational speed, low traverse speed, and a square tool pin profile.