STRAY
ARC
Local damage to the surface of the parent metal
adjacent to the weld, resulting from arcing or striking the arc outside the
weld groove, this results in random areas of fused metal where the electrode,
holder, or current return clamp have accidentally touched the work.
Causes
Poor access to the work
Missing insulation on electrode holder or torch
Failure to provide an insulated resting place for
the electrode holder or torch when not in use
Loose current return clamp
Adjusting wire feed (MAG welding) without isolating welding
current
Prevention
Improve access (modify assembly sequence)
Institute a regular inspection scheme for electrode
holders and torches
Provide an insulated resting place
Regularly maintain current return clamps
Retrain welder
Comments
An arc strike can produce a hard HAZ, which may
contain cracks. These can lead to serious cracking in service. It is better to
remove an arc strike by grinding than weld repair.
SPATTER
Globules of weld or filler metal expelled during
welding and adhering to the surface of parent metal or solidified weld metal.
Causes
High arc current
Long arc length Magnetic arc blow
Incorrect settings for GMAW process
Damp electrodes
Wrong selection of shielding gas (100% CO2)
Prevention
Reduce arc current
Reduce arc length
Reduce arc length or switch to AC power
Modify electrical settings (but be careful to
maintain full fusion!)
Use dry electrodes
Increase argon content if possible, however too high
a % may lead to lack of penetration
Comments
Spatter in itself is a cosmetic imperfection and does
not affect the integrity of the weld. However as it is usually caused by an
excessive welding current, it is a sign that the welding conditions are not
ideal and so there are usually other associated problems within the structure
i.e. high heat input. Note that some spatter is always produced by open arc
consumable electrode welding processes. Anti-spatter compounds can be used on
the parent metal to reduce sticking and the spatter can then be scraped off.
TORN
SURFACE
Surface damage due to the removal by fracture of
temporary welded attachments, the area should be ground off, then subjected to
a dye penetrant or magnetic particle examination and then restored to its
original shape by welding using a qualified procedure. NOTE: Some applications
do not allow the presence of any overlay weld on the surface of the parent material.
ADDITIONAL
IMPERFECTION
Grinding
mark
Local damage due to grinding
Chipping
mark
Local damage due to the use of a chisel or other
tools
Under
flushing
Lack of thickness of the work piece due to excessive
grinding
Misalignment
of opposite runs
Difference between the centerlines of two runs made
from opposite sides of the joint.
Temper
color (visible oxide film)
Lightly oxidized surface in the weld zone, usually
occurs in stainless steels.
Comments
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