Friction stir welding effect on transverse rigidity and sound transmission characteristics of AZ31B magnesium alloy

Abstract

Abstract：AZ31B magnesium alloy was subjected to friction stir welding with various welding parameters. The equivalent Young's moduli of the friction stir welded samples and the base material were obtained by the three-point method, and their transverse rigidities were obtained as well. Furthermore, the sound transmission characteristics of those samples were experimentally studied by four-microphone impedance tube method. The experimental results indicate that the transverse rigidities of the friction stir welded samples were only 79%, 83% and 92% of those of the base material, respectively. The sound transmission losses of the processed samples were also lower, which was largely due to the reduction of transverse rigidities induced by the decrease of equivalent Young's moduli. Keywords：AZ31B magnesium alloy; friction stir welding; transverse rigidity; sound transmission loss Magnesium alloy is expected to have widespread applications in the fields of communication, automobile and aerospace industry for its excellent physical and mechanical properties, such as low density, high stiffness, high strength to weight ratio, good sound shielding and damping characteristics [1][2][3] . Refs. [4][5][6] showed that magnesium alloys may have a promising future as potential degradable implant materials [7] . Welding technology is indispensable for the application of magnesium alloy. However, porosity, coarse microstructure, severe deformation and high residual stress are also introduced to the joints [8] .As a solid state process, friction stir welding (FSW) is not only energy-efficient, but also environment friendly [9] . Before welding, a specially designed rotating tool consisting of a shoulder and a pin is inserted into the edges of the sheets to be welded with a proper tilt angle, until the shoulder gets in contact with the top surface of the sheets, then the rotating tool is moved along the welding line [9][10][11][12] . The combined effect of tool rotation and translation involves heat generation, and induces a strong plastic deformation of the work piece, promoting its complex mixing across the joint [13] . Many problems associated with conventional fusion welding processes can be avoided by FSW. Researchers have studied the microstructure, hardness, texture, fracture and strength of friction stir welded (FSWed) magnesium alloys [14][15][16] . However, there is few literature on the transverse rigidity (TR) or the sound transmission characteristics.In this paper, AZ31B magnesium alloy was FSWed with different rotation rates and transverse speeds. The TRs were experimentally studied by three-point method. In addition, the sound transmission characteristics were investigated by four-microphone impedance tube method. The same experiments were also conducted on base material (BM) for comparison.

Optimization of parameters and formulation of numerical model employing GRA–PCA and RSM approach for friction stir welded Ti–6Al–4V alloy joints

“…The reason for choosing these two joints was that the experiment no.20 possesses highest GRG value (i.e., 29989) and Figure 7(a) demonstrates that the surface of the fractured surface is flat and slightly inclined towards the axis of loading. Figures 7(b) and (c) are magnified views of that fractured surface and these images reveals us the existence of laterally contracted area, which is a direct evident for the reasonable necking at the region of plasticized instability, where strain hardening have failed to compensate for the reduction in the area, before the fracture based failure [38,39].…”