D.H. Lammlein PhD Dissertation - Vanderbilt University

Figure 115: (Unsupported, conical tool) The tool is deflected towards the advancing,
trailing quadrant.
For a valid comparison of partial and full penetration welds, both the apparent
stress and the true stress of the partial penetration welds must be considered in the
analysis. The true stress differs significantly from the apparent stress in the case of a
partial penetration weld because the depth of the weld nugget differs significantly from
the thickness of the material. Figure 116 defines the true and apparent stress of the weld
samples. In the case of full penetration welds, the difference between true and apparent
stress is small and is due an indentation left at the weld surface which was approximately
0.008” in depth. The apparent strength is of more practical significance because the
entire thickness of the butted surfaces is available for joining and any indentation at the
material surface or lack of penetration at the weld root is not desired. Tensile results are
presented in Figure 117. The partial penetration, unsupported welds reached a maximum
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