D.H. Lammlein PhD Dissertation - Vanderbilt University

Figure 109: Lateral macrosections for partial-penetration, unsupported welds made with
the conical tool. Samples are taken from the steady-state portion of each weld.
The axial force data, presented in Figure 110 and Figure 111, shows Z direction
force decreasing with increasing rotational speed and an increasing with increasing
traverse speed. Increased rotational speed can to soften the material (reduce viscosity)
due to increased heat input (if torque remains somewhat constant) and increased shearing
forces. A higher traverse rate means a colder weld and reduced axial force. It should be
noted that the axial force was significantly lower for all parameters with the conical tool
in unsupported welds.
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