Tweco 170 HF Weldskill - Manual (Page 40)

WELDSKILL 170 HF INVERTER
5-4 April 23, 2008
6 Non-metallic particles are trapped
in the weld metal (slag inclusion)
A Non-metallic particles may
be trapped in undercut from
previous run
A If bad undercut is
present, clean slag out
and cover with a run from
a smaller diameter
electrode
B Joint preparation too
restricted
B Allow for adequate
penetration and room for
cleaning out the slag
C Irregular deposits allow slag
to be trapped
C If very bad, chip or grind
out irregularities
D Lack of penetration with
slag trapped beneath weld
bead
D Use smaller electrode with
sufficient current to give
adequate penetration. Use
suitable tools to remove
all slag from corners
E Rust or mill scale is
preventing full fusion
E Clean joint before welding
F Wrong electrode for position
in which welding is done
F Use electrodes designed
for position in which
welding is done,
otherwise proper control
of slag is difficult
Possible Cause Description Remedy
Not cleaned, or incorrect electrode
Slag trapped in
undercut
Slag trapped in root
Art # A-05868
Figure 5-4: Examples of Slag Inclusion