Abstract
Thin sheets of lightweight aluminum alloys, which are increasingly used in automotive, aerospace, and electronics industries to reduce the weight of parts, are difficult to weld. When applying micro-friction stir welding (μ-FSW) to thin plates, the heat input to the base materials is considerably important to counter the heat loss to the jig and/or backing plate. In this study, three different backing-plate materials—cordierite ceramic, titanium alloy, and copper alloy—were used to evaluate the effect of heat loss on weldability in the μ-FSW process. One millimeter thick AA6061-T6 and AA5052-H32 dissimilar aluminum alloy plates were micro-friction stir welded by a butt joint. The tensile test, hardness, and microstructure of the welded joints using a tool rotational speed of 9000 rpm, a welding speed of 300 mm/min, and a tool tilting angle of 0° were evaluated. The heat loss was highly dependent on the thermal conductivity of the backing plate material, resulting in variations in the tensile strength and hardness distribution of the joints prepared using different backing plates. Consequently, the cordierite backing plate exhibited the highest tensile strength of 222.63 MPa and an elongation of 10.37%, corresponding to 86.7% and 58.4%, respectively, of those of the AA5052-H32 base metal.
Highlights
Aluminum alloy parts have been increasingly used in the electronics industry and for transportation in the fields of automobile, rail, ship, and aerospace manufacturing to achieve weight reduction and the associated energy savings [1,2,3,4]
The heat loss was highly dependent on the thermal conductivity of the backing plate material, resulting in variations in the tensile strength and hardness distribution of the joints prepared using different backing plates
Micro-friction stir welding (μ-FSW) uses the frictional heat and stirring force generated between a rotating tool and the base material to form a weld
Summary
Aluminum alloy parts have been increasingly used in the electronics industry and for transportation in the fields of automobile, rail, ship, and aerospace manufacturing to achieve weight reduction and the associated energy savings [1,2,3,4]. Micro-friction stir welding (μ-FSW) uses the frictional heat and stirring force generated between a rotating tool and the base material to form a weld. The heat generated by friction between the rotating tool and the plates promotes a local increase in temperature and softens the materials under the tool shoulder. The plunged rotating probe moves and mixes the softened materials by intense plastic deformation, welding both in a solid-state weld [7]. This method is considered to be an eco-friendly welding method, as it produces no fumes from spatter or arc flashes [8].
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