Specifications

16
Slag inclusions occur when slag particles are
trapped inside the weld metal which produces a
weaker weld. These can be caused by:
•erratictravelspeed
•toowideaweavingmotion
•slagleftonthepreviousweldpass
•toolargeanelectrodebeingused
•lettingslagrunaheadofthearc.
This defect can be prevented by:
•auniformtravelspeed
•atighterweavingmotion
•completeslagremovalbeforewelding
•usingasmallerelectrode
•keepingtheslagbehindthearcwhichisdone
by shortening the arc, increasing the travel speed,
or changing the electrode angle.
Undercutting
UNDERCUTTING
Undercutting is a groove melted in the base
metal next to the toe or root of a weld that
is not filled by the weld metal. Undercutting
causes a weaker joint and it can cause cracking.
This defect is caused by:
•excessiveweldingcurrent
•toolonganarclength
•excessiveweavingspeed
•excessivetravelspeed.
On vertical and horizontal welds, it can also
be caused by too large an electrode size and
incorrect electrode angles. This defect can be
prevented by:
•choosingtheproperweldingcurrentforthe
type and size of electrode and the welding
position
•holdingthearcasshortaspossible
•pausingateachsideoftheweldbeadwhena
weaving technique is used
•usingatravelspeedslowenoughsothatthe
weld metal can completely fill all of the melted
out areas of the base metal.
Lack of Fusion
LACK OF FUSION
Lack of fusion is when the weld metal is not
fused to the base metal. This can occur between
the weld metal and the base metal or between
passes in a multiple pass weld. Causes of this
defect can be:
•excessivetravelspeed
•electrodesizetoolarge
•weldingcurrenttoolow
•poorjointpreparation
•lettingtheweldmetalgetaheadofthearc.
Lack of fusion can usually be prevented by:
•reducingthetravelspeed
•usingasmallerdiameterelectrode
•increasingtheweldingcurrent
•betterjointpreparation
•usingaproperelectrodeangle.