Chapter 18 Weld Inspection and Repair
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Notch-Toughness Test
Notch-toughness tests are used to defi ne the
ability of welds to resist cracking or crack propagation
at low temperatures under loads. These tests are used
on welds that are intended for use in low temperature
environments with pulsating or vibrating loading.
The weldment is cut into test coupons, which are then
notched, cooled to a low temperature, and put under
pressure until they fail.
The test coupons are cut from the test weld. They
are prepared for either a Charpy or an Izod impact
test, Figure 1 8-15. The test bars are cooled to the test
temperature and then placed into the test machine
and broken, Figure 18-16. The results are measured
in the energy required to make the coupon break and
are expressed in foot-pounds. Comparisons are then
made with the original material and specifi cation
requirements.
Cross Section Test
Cross section tests are used to defi ne the internal
quality and structure of the weld. The weldment is cut
Figure 18-14. This tensile test machine has a recorder mounted
on the side to record the test operation parameters and results.
A tensile test machine can be equipped with fi xtures for holding
weld coupons for testing. (Photo courtesy of Tinius Olsen)
Charpy Test Specimen
Izod Test Specimens
Figure 18-15. Charpy and Izod test bar dimensions.