©
COPYRIGHT 2000 THE ESAB GROUP, INC. LESSON
IV 4.4.1.2
Chromium - When chromium
is added to the weld metal, the corrosion and high
temperature scaling resistance are
increased. The combination of chromium and molybde-
num allows the weld metal to retain
high strength levels at medium high temperatures. 4.4.1.3
Nickel - Mild steel
weld metal usually becomes brittle at temperatures below -20°F.
The addition of 1-3% nickel to the
weld metal enables the weld metal to remain tough at con-
siderably lower temperatures. The
presence of the nickel also makes the weld metal more resistant
to cracking at room temperature. 4.4.1.4
Manganese - The presence
of 1-1/2% to 2% manganese in weld metal increases
the tensile strength and when 1/3%
molybdenum is added in combination, the high strength weld
metal is crack resistant. 4.4.1.5
It should be noted that the A5.5-96
specification covers not only the low alloy low hydrogen
electrodes, but also low alloy versions of the cellulosic, titania, and iron oxide
type electrodes.
A full list of all the electrodes covered by this specification is presented
in Table 2. TABLE
2. Electrode Classifications of AWS A5.5 Specification
E7010-A1 E8018-B2
E9015-B3L E11018-M
E7011-A1 E8018-B2L
E9016-B3 E12018-M
E7015-A1 E8015-B4L
E9018-B3 E7016-A1
E8016-B5 E9018-B3L
EXX10-G E7018-A1
E8016-C1 E9015-D1
EXX11-G E7020-A1
E8018-C1 E9018-D1
EXX13-G E7027-A1
E8016-C2 E9018-M
EXX15-G E8018-C2
EXX16-G E8016-B1
E8016-C3 E10015-D2
EXX18-G E8018-B1
E8018-C3 E10016-D2
E7020-G E8015-B2L
E10018-D2 E8016-B2
E9015-B3 E10018-M
4.4.2
Mechanical
Properties (AWS
A5.5-96)
- Since many low alloy steels require
some post-weld heat treatment to relieve
the internal stresses generated from the welding process,
physical testing on the weld metal of most low alloy electrodes is required to
be performed
after the specimen has been stress-relieved. Only the E8016-C3, E8018-C3,
E9018-M, E11018-M, and E12018-M types
are permitted to be tested in the as-welded condi- tion
for classification purposes.
