CYCLIC STRAIN RESISTANCE AND CYCLIC FRACTURE-BEHAVIOR OF 2124 ALUMINUM-ALLOY

In this paper, the cyclic strain resistance and cyclic fracture behavi our of aluminium alloy 2124 are examined. Test specimens of the alloy were cycled using tension-compression loading, under total strain cont rol, over a range of plastic strains giving less than 10(4) cycles to failure. The alloy displayed hardening in both the longitudinal and tr ansverse directions of the wrought plate.The observed hardening behavi our is ascribed to contributions from synergistic influences of disloc ation multiplication and dislocation-dislocation interactions. The all oy followed the Coffin-Manson relation and exhibited a single slope fo r the variation of cyclic plastic strain amplitude with reversals to f ailure. Fracture of the alloy samples was predominantly transgranular for both orientations, with microscopic crack propagation along the gr ain boundaries. The low-cycle fatigue characteristics and fracture beh aviour of the alloy are discussed in terms of competing and synergisti c influences of cyclic plastic strain amplitude, response stress, intr insic microstructural effects and dislocation-microstructure interacti ons during cyclic straining.