Anelastic creep behaviour of RR-58 aluminum alloy at 180 °C: Phenomenological aspects and analysis based on the unbowing of dislocation segments

The strain relaxation behaviour after full stress removals during creep of RR-58 Hiduminium alloy has been observed. Creep tests were carried out at 180 °C, with stresses of 120, 170 and 230 MPa. Tests involved a series of unloading cycles after different creep periods involving the primary and secondary creep stages. The results were interpreted according to a model based on the thermally activated unbowing of dislocation segments. Activation parameters were calculated and an interpretation of the phenomena is made in terms of microstructural details of the material. The appearance of the fast and slow anelastic creep stages may be just a consequence of the high non-linearity existing between the line tension and the area swept by the segments during their unbowing movement.