Figure 7-67.-Performing impact test.

fracturing. This is a dynamic test in which a test specimen is broken by a single blow, and the energy used in breaking the piece is measured in foot-pounds. This test compares the toughness of the weld metal with the base metal. It is useful in finding if any of the mechanical properties of the base metal were destroyed by the welding process.

The two kinds of specimens used for impact testing are known as Charpy and Izod (fig. 7-66). Both test pieces are broken in an impact testing machine. The only difference is in the manner that they are anchored. The Charpy piece is supported horizontally between two anvils and the pendulum strikes opposite the notch, as shown in figure 7-67, view A. The Izod piece is supported as a vertical cantilever beam and is struck on the free end projecting over the holding vise (fig. 7-67, view B).

Fillet-Welded Joint Test

You use the FILLET-WELDED JOINT TEST to check the soundness of a fillet weld. Soundness refers to the degree of freedom a weld has from defects found by visual inspection of any exposed welding surface. These defects include penetrations, gas pockets, and inclusions. Prepare the test specimen, as shown in figure 7-68. Now apply force at Point A

Figure 7-68.-Test plate for fillet weld test.