Welding Discontinuities
Some
examples of welding discontinuities are shown below.
Evaluation of the discontinuity will determine if the
discontinuity is a defect or an acceptable condition:
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Incomplete Fusion - A weld discontinuity in
which fusion did not occur between weld metal
and fusion faces or adjoining weld beads. |
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Undercut - A groove melted into the base metal
adjacent to the weld toe or weld root and left
unfilled by weld metal.
Overlap - The protrusion of weld metal beyond
the weld toe or weld root. |
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Underfill - A condition in which the weld face
or root surface extends below the adjacent
surface of the base metal.
Incomplete Joint Penetration - A joint root
condition in a groove weld in which weld metal
does not extend through the joint thickness |
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Partial joint penetration groove welds are
commonly specified in lowly loaded structures.
However, incomplete joint penetration when a
full penetration joint is required, as depicted
above, would be cause for rejection. A fix for
an incomplete penetration joint would be to back
gouge and weld from the other side. Another
acceptable partial penetration joint is shown
below. |
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Partial penetration joint
on the left without discontinuities is an
acceptable condition where appropriate.
Appropriate engineering decisions need to be
applied to determine what type of joint should
be specified for a given application. |
Please
contact us to determine whether partial penetration of
full penetration joints are appropriate for a particular
situation.
Above are
several different representations of weld Cracking
Below is a
representation of a convex fillet weld without
discontinuities.
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