4. Resilience testing

4.1 Metal brittleness

Knowledge of the mechanical properties deduced from the tensile test may be insufficient, since fractures may be obtained below the elastic limit under particular conditions that render the metal brittle.

Weakening factors include :

• triaxiality of stresses: when a part is subjected to compressive stresses in three mutually perpendicular directions, a crack may propagate in the most brittle direction of the part; this triaxiality can be artificially induced by the presence of a notch or a stress concentration zone;

• lowering the temperature: at very low temperatures, the ductility of the metal decreases considerably, which can lead to brittle fracture;

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