|
Welding Terms
Lack of Fusion (LOF)
- Also known as cold-lapping or cold shuts, LOF
occurs when there is no fusion between the weld
metal and the base metal. The most common cause of
lack of fusion is a poor welding technique. Another
cause is the use of a very wide weld joint. If the
arc is directed down the center of the joint, the
molten weld metal will only flow and cast against
the side walls of the base plate without melting
them.
Lack of Penetration (LOP)
- A weld defect where the welding process does not reach all the
way into the seam between the pieces being welded.
Incomplete penetration is usually caused by the use
of too low a welding current and can be eliminated
by simply increasing the amperage. Other causes can
be the use of too slow a travel speed, an incorrect
torch angle or too narrow of a gap between pieces.
Gusset -
Triangular metal piece added to a corner to add
strength to the joint.
Fitup - The
initial positioning of pieces before welding or
fastening.
Fitup Gap - A
space between pieces when they are being positioned
for welding. The gap may remain after welding or it
may be filled by the weld.
Tack Weld - A
small, temporary weld placed at intervals along a
joint to hold the joint in alignment.
Fillet Weld - A
weld of approximately triangular cross section, as
used in a lap joint, joining two surfaces at
approximately right angles to each other.
Undercut -
Undercutting is a defect that appears as a groove in
the parent metal directly along the edges of the
weld in the weld toe. This type of defect is most commonly caused by
improper welding parameters; particularly the travel
speed and arc voltage.
Weld Toe - The
junction of the weld face and the base metal.
Re-Entrant Angle
- The angle formed by the weld and base metal
intersection after welding.
Capping Pass -
The final pass in welding a joint, sometimes done
for cosmetic purposes.
|
Dr.
R. Craig Jerner, Ph.D., PE specializes in accident
investigation and metallurgical failure analysis,
with over 30 years experience as a metallurgical
consultant and accident investigator. He has
testified as a metallurgical expert in over 250
depositions and more than 70 court appearances. If you or someone you know should need the services of Dr. Jerner and J.E.I. Metallurgical, please visit our web site at the buttons below, or e-mail Dr. Jerner --- 