MetFab - Air Products Welder's Handbook - Flipbook - Page 35
Undercut
Spatter
Causes:
Causes:
Base material is melted by the arc and
an undercut is formed as a groove or dip
in the parent material directly along the
edges of the weld. It is often present as a
shape discontinuity at the weld toe which
only constitutes a defect if it exceeds the
specification limits.
Spatter is caused by arc instabilities
during metal transfer which cause molten
metal droplets to be expelled from the arc.
Prevention methods:
• ensure correct weld process gas is
selected
• reduce travel speed
• reduce arc voltage
• reduce welding current
Prevention methods:
• optimise welding parameters, paying
particular attention to arc voltage
• ensure welding equipment is in good
working order
• maintain correct torch angle
• ensure joint faces are clean and free
of excessive mill scale and slag
• ensure correct weld process
gas selection
• maintain correct torch angles
(push technique)
Undercut
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