©
COPYRIGHT 2000 THE ESAB GROUP, INC. LESSON
IV 4.4.3
Impact
Properties -
Since many low alloy steels are developed for low tempera-
tures service, impact properties of
the weld metal designed to join these steels are very impor-
tant. Except for those types
already mentioned, all impact testing is performed on specimens
after they have been stress-relieved.
Table 3 lists the minimum charpy v-notch impacts re-
quired in the A5.5 specification.
TABLE 3. Impact
Requirements for AWS A5.5 Specification AS
WELDED MINIMUM
REQUIREMENT STRESS-RELIEVED
E8016-C3 )-------
20 ft.-lbs. @-40°F.
E8018-C3 )
E9018-M )
( E9015-D1
E10018-M )
( E9018-D1
E11018-M )-------
20 ft.-lbs. @-60°F. --------
( E10015-D2
E12018-M )
( E10016-D2
( E10018-D2
( E8016-C1
20 ft.-lbs. @-75°F. --------
( E8018-C1
( E8016-C2
20 ft.-lbs. @-100°F.-------
( E8018-C2
Impact values for all
other classifications are not required.
4.5 SELECTING
THE PROPER LOW ALLOY ELECTRODE As
stated earlier, low alloy electrodes are often selected to match the properties
of the steel to be
welded rather than matching the exact chemical composition of the steel. These
properties (i.e.,
strength, toughness, creep, and corrosion resistance) reflect the type of service
for which the
steel is intended. The letter-number suffix of the electrode classification
gives an indication of
that service. Whenever possible, the electrode should be selected on the
basis of the appropriate
strength levels and the intended service of the weldment.
4.5.1
Service
Conditions -
The large family of "proprietary" steels that are sold in the as
rolled, controlled, cooled condition
have a 50,000 psi minimum yield point and 70,000 psi minimum
tensile strength. Electrodes that deposit low hydrogen weld metal of those
strength levels
are used to weld them.
