Abstract
Friction stir welding is a solid‐state welding method that produces joints with superior mechanical and metallurgical properties. However, the negative effects of the thermal cycle during welding dent the mechanical performance of the weld joint. Hence, in this research study, the joining of aluminum tailor welded blanks by friction stir welding is carried out in underwater conditions by varying the welding parameters. The tensile tests revealed that the underwater welded samples showed better results when compared to the air welded samples. Maximum tensile strength of 229.83 MPa was obtained at 1000 rpm, 36 mm/min. The improved tensile strength of the underwater welded samples was credited to the suppression of the precipitation of the secondary precipitates due to the cooling action provided by the water. The lowest hardness of 72 HV was obtained at the edge of the stir zone which indicated the weakest region in the weld zone.
Highlights
Friction stir welding (FSW), a solid welding technique, is employed to produce weldments with superior joint properties when compared to conventional welding methods
Wahid et al [20] concluded that low peak temperatures obtained in submerged friction stir welding due to water cooling resulted in denting of grain growth and dissolution of precipitates that enhanced the strength of the weld joint
Results and Discussion e mechanical properties of underwater welded samples at different tool rotational speeds are compared. e underwater welded samples possessed high strength than the air welded samples. e samples welded at a constant weld speed of 24 mm/min were observed with tunnel defects. e tunnel defects are formed due to insufficient plasticization and poor material mixing by the tool profile at the specific welding speed [22]
Summary
Friction stir welding is a solid-state welding method that produces joints with superior mechanical and metallurgical properties. In this research study, the joining of aluminum tailor welded blanks by friction stir welding is carried out in underwater conditions by varying the welding parameters. E tensile tests revealed that the underwater welded samples showed better results when compared to the air welded samples. Maximum tensile strength of 229.83 MPa was obtained at 1000 rpm, 36 mm/min. E improved tensile strength of the underwater welded samples was credited to the suppression of the precipitation of the secondary precipitates due to the cooling action provided by the water. E lowest hardness of 72 HV was obtained at the edge of the stir zone which indicated the weakest region in the weld zone Maximum tensile strength of 229.83 MPa was obtained at 1000 rpm, 36 mm/min. e improved tensile strength of the underwater welded samples was credited to the suppression of the precipitation of the secondary precipitates due to the cooling action provided by the water. e lowest hardness of 72 HV was obtained at the edge of the stir zone which indicated the weakest region in the weld zone
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