In the welding time there are some weld defects are found, which is may cause of
damaging the job or reducing the job life. If we take some awareness of welding then
it may be prevented. The welding defects are
Lack of Penetration.
Extra spatter deposition
The major welding defects are describing bellow.
Lack of penetration:
The lack of penetration is one kind of welding faults. If the molten base metal does
not filled the correct design depth of base metal it is called lack of penetration.
Whether that penetration can be obtained depends upon the accessibility of the heat
source and filler rod to the face area. The lack of joint penetration may result
from improper technique, insufficient welding heat, improper fit-up, or improper
If all other factors are correct, proper fusion depends on the skill and technique
of the welder, the technique of welder mostly depends on the type and position of
the joint. The lack of penetration may also depends of too long arc, always keep
the arc as short as possible.
Porosity or blow holes:
If air trap inside the molten metal or trapping air comes out through the molten
metal it makes the small holes it caused porosity or blow holes. The entrapped gas
comes from either the gas used in the welding process or the gas released from chemical
reaction occurring during the welding process. Proper welding technique avoids gas
formation and entrapment. One o the main factors contributing to this fault is the
condition of the electrode, particularly the moisture content of the coating. The
essential factor depends upon electrodes design which should be base metal related.
The current is the essential part for the porosity, too low a welding current is
generally more frequent cause of porosity than too high current. Rust, scale, galvanizing,
oil or dampness on the work surface promote porosity.
Slag or other non-metallic foreign matter entrapped in the weld joint its called
slag inclusion. The usual source is the slag formed by the electrode coating and
dirty surface is also other cause. The correct weld joint design is can play very
important part. The another most cause of slag inclusions is inadequate removal of
the slag between the deposition of successive runs in which is associated with undercutting
or unevenness of surface.
Cracks are occur in the weld and /or base metal when localized stress is exceed.
The crack generally associated with notches, discontinuity welding and base metal,
with high residual stresses and sometimes with hydrogen embrittlement. Where the
metal were harden there are generally observed cracks. Cracks are generally divided
into two major parts, which is hot cracks and cold cracks. The hot cracks are formed
in high temperature and cold cracks are formed after solidification is completed.
To avoiding the cracks the welder should avoid rapid cooling the weld.