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Title
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Tensile behavior, microstructure, and substructure
of the friction stir welded 70/30 brass joints:
RSM, EBSD, and TEM study
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Abstract
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The effect of bead on plate friction stir welding parameters on the tensile properties of the
70/30 brass joints was investigated using response surface method. The microstructures of
the joints were characterized using optical microscopy, electron backscattered diffraction
(EBSD), and transmission electron microscopy (TEM). The tensile test was conducted to
measure the ultimate tensile strength and elongation of the joints. In addition, the fracture
surfaces of the tensile specimens were analyzed by scanning electron microscopy (SEM). The
results showed that the most effective parameters on the strength and elongation of the
joints were tool rotational speed and axial force, respectively. Optimizing the parameters
revealed that the maximum strength and elongation of 318.5 MPa and 54.9% can be achieved
at a rotational speed of 1000 rpm, a traverse speed of 58.4 mm/min, and an axial force of
3 kN. The strengthening mechanisms of grain boundary and dislocation density effects were
responsible for the higher ultimate tensile strength of the joints welded at the lower heat
input conditions. Furthermore, the effect of friction stir parameters on the ultimate tensile
strength and elongation of the joints has been discussed, thoroughly.
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