Copyright Goodheart-Willcox Co., Inc. Chapter 18 Weld Inspection and Repair 273 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 fixtures for holding weld coupons for testing. (Photo courtesy of Tinius Olsen) 2 mm .25 mm R 130 mm 10 mm 45˚ 45˚ .25 mm R 75 mm 10 mm 2 mm 46 mm 28 mm 28 mm 28 mm 10 mm 10 mm 28 mm 47 mm .25 mm R 45˚ 2 mm 27 mm 27.5 mm 55 mm 10 mm 10 mm Charpy Test Specimen Izod Test Specimens Figure 18-15. Charpy and Izod test bar dimensions.