BONDING STRENGTH Figure 8 shows the dependence of the bonding strength on impact velocity. It was reported previously that the bonding strength of the impact-welded bars is independent of impact velocity because a fracture has not occurred at the joining interface, but on the aluminum projectile. However, as shown in Fig. 8, the bonded strength of the tube decreases with higher impact velocities. The difference of the two tendencies depends on the following difference of the deformation processes of the bar and tube. 300 280 260 240 220 0 100 200 Impact velocity v m/s Bonding strength MPa σ Fracture strength of Al Fig. 8 Effect of impact velocity on bonding strength The radial deformation was generated at the impact face of the cylindrical projectile subjected to a longitudinal impact. Since the radial displacement increases with the radial distance at symmetric deformation with respect to the axis, the deformation applies a shearing force on the joint. In the case of impact welding of the bar, the compound layer hardly suffers deformation because the layer was formed in the vicinity of the center. However, since the forming position of the compound layer at the impact face of the tube is near the inner wall, a shearing force acts on the interface. It is also clarified that the shearing deformation (a) v = 233 m/s (b) v = 260 m/s Fig. 9 EDX images of fracture surface obtained by tension test
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