The Effect of Fatigue Pre-Cracking Versus V-Notching on Impact Testing of Charpy Specimens

Charpy impact testing was carried out on both V-notch and fatigue pre-cracked specimens of two steels: AAR M128, and ASTM A212-65. Values of total energy absorbed, lateral expansion and shear fracture appearance were found for both types of specimen. The total energies absorbed by the fatigue pre-cracked specimens were markedly less than those by V-notch samples. Transition temperature ranges were found for both the V-notch and pre-cracked specimens. The energy absorption results show a small increase in transition temperatures for the pre-cracked specimens. The lateral expansion results are the same in both types of specimen for the AAR M128 steel and show only a small change in the ASTM A212-65 steel. Also for the A212 steel the shear fracture appearance results can be represented by a single curve for V-notch and pre-cracked specimens. However, for the M128 steel these curves occur at lower temperatures for the pre-cracked specimens.