D.H. Lammlein PhD Dissertation - Vanderbilt University

with a 100º conical tool (0.025” diameter snub-nose and 0.015” cupped nose recess) at
800rpm, 5.2 ipm, and a penetration depth of 0.11”. Figure 120 shows a similar weld
made at 1000rpm, 10.4ipm, and a penetration depth of 0.11”. At this depth, unsupported
welds made with the conical tool begin to split and protrude at the root for some of the
tested weld parameters. The initiation of protrusion and splitting in the weld root at
0.110” was deemed undesirable by the authors for the some suggested applications
(under external compression the strength is maintained only when the full butted jointline
is undeformed). The experimental matrix was therefore performed at 0.100” where this
did not occur. It should be noted however that the strength of the unsupported welds
increased with depth beyond the experimental matrix depth of 0.100”. This can be seen
in Figure 118 which shows the apparent tensile strength of all conical tool, partial
penetration, unsupported welds performed.
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