©
COPYRIGHT 2000 THE ESAB GROUP, INC. LESSON
III
E7016. The smooth arc and easy
welding with the E7018 electrode make it a welder's favor-
ite. The relatively high welding
currents and the addition of the iron powder melting into the
weld metal result in higher deposition
rates and higher deposition efficiencies. The E7018
covered mild steel electrode deposits
the highest quality weld metal available from manual arc
welding. The only major disadvantage
of the E7018 is the need to be kept dry. Electrodes
that have picked up moisture by exposure
to the atmosphere or other sources deposit porous weld
metal. Also E7018 electrodes cannot be used to weld the root pass in an
open butt joint without
excess porosity. When E7018 electrodes are to be used in butt welds, the
root should be
closed by a backing bar, ceramic back-up tape, or consumable insert. If
a backing bar is used,
it must be removed after the joint is welded by the gas metal arc or the gas tungsten
arc process and
successive passes applied with E7018 for a high quality weld metal deposit.
3.4.1.7 The
E7024 classification of covered
mild steel electrodes is the result of heavy additions
of iron powder to the E6012 formulation and large increases in the amount of coat-
ing on the core wire. About 50%
of the coating is iron powder. Very high deposition rates and
deposition efficiencies result from
this combination of more coating and iron powder. The
electrode is limited to welding horizontal
fillets and flat positions. The quality of the weld metal
is not as high as that from E7018 electrodes
since the ductility of E7024 weld metal is lower. 7
6 5
4 3
2 150
200
250 DEPOSITION
RATE 5/ 32" DIA.
COVERED ELECTRODES
WELDING AMPERES
DEPOSITION RATE, 5/32" DIAMETER COVERED
ELECTRODES FIGURE
4
