Volume 16, Issue 2 (March 1988)
Investigation of the Influence of Impact Velocity and Temperature on the Dynamic Mechanical Properties of the Material 22 NiMoCr 37
Precracked modified Charpy subsize impact test specimens of the nuclear reactor pressure vessel material 22 NiMoCr 37 (similar to SA 508 Class II) have been impact tested in the as-received condition. Impact tests were performed at temperatures 233 ≤ T/K ≤ 423. Specific impact energies were determined by (1) dial readings, (2) integration of load versus load point displacement diagrams, and (3) integration of load versus time diagrams. In all cases the agreement was excellent.
The evaluation of the impulse for the different impact velocities revealed clearly the different behavior of the dynamic processes during impact. A unique graphical function for the impulse versus temperature diagrams for the different initial impact velocities was found.
The dynamic fracture toughness values were determined for the different temperatures following the equivalent energy approach for the upper shelf regime. In the other cases the rules for the 95% secant method or the load maximum were applied. The transition temperature between upper and lower shelves for the specific absorbed energies and the dynamic fracture toughness values were not equal; this fact can be explained by the technique applied for the fracture toughness determination.