Defect mane
Caused reasons
Prevent methods
Blowhole
There are some dust like oil,
rust or water on the workpiece
surface and groove
The coating of electrode is
damped & is not drying
Under current or over speed
in the welding
The arc is too long or lean
burning, the molten pool
protection is not good
Over current, the coating of
electrode falls off and lose
protection
Manipulation of electrode is
not proper
Clear out the dust around
groove for about 20
–
30mm
Strictly
to
dry
the
electrode according to
manual
Correctly
to
choose
parameters
and
to
operate
Using
the
short
arc
operation
Welding operation in the
field
should
have
anti-wind protection
Do not use the invalid
electrode
Inclusion & slag inclusion
The slag clears bad in the
middle layer in the welding
process
Under current or over speed
in the welding
Welding operation is not
proper
The welding material can not
match the work piece
The
groove
design
&
processing are not proper
Choosing the electrode of
good slag detachability
Strictly to clear the slag in
the layers
Correctly to choose the
welding parameters
Adjusting the electrode
angle and manipulation
way
Hot crack
In the process of solidification,
the inter crystal segregation is
seriously caused. At the same
time, with the effect of welding
stress, the hot crack is
formed.
Strictly
control
the
percentage of S and P in
welding material.
Adjust the structure of
welding material.
Adopt the basic electrode.
Cold crack
Three reasons will cause cold
crack;
The structure turned from the
marten site
The residual stress caused by
big restraint intensity
The residual hydrogen in
welding gap.
Adopt low hydrogen type
basic electrode.
Bake under the instruction
before use.
Remove the feculence
before use, reduce the
percentage of hydrogen
Adopt
appropriate
parameters and heat input
After
welding,
do
dehydrogenation at once.
Summary of Contents for INARC 200 IDS
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