Phenomenological study of the plastic behaviour of aluminium at low and medium temperatures

✍ Scribed by G. Ferron; M. Mliha-Touati

• Publisher: Elsevier Science
• Year: 1987
• Weight: 823 KB
• Volume: 35
• Category: Article
• ISSN: 0001-6160
• DOI: 10.1016/0001-6160(87)90009-5

✦ Synopsis

Ah&act-The plastic behaviour of 1050 aluminium is studied by means of conventional tension tests, temperature change tests and load relaxation tests in the temperature range 77-540 K, A major difference is observed between the high-tem~rature region (above -300 K), where a long plastic transient is observed after a temperature change, and the low-temperature region where the transient is absent. On the basis of a state-variable description of material behaviour, a one-parameter model can account for the low-temperature regime, while a two-parameter model is required at high temperature. Three methods are proposed to obtain "isostructural curves" in the axes of the stress vs the temperature-compensated strain-rate. These curves are expected to be related to quasi-constant values of the internal variable p, (with the slower evolution rate), but to the saturation value, at the strain-rate and temperature of the test, of the internal variable pz (with the more rapid evolution rate). It is argued that these variables are connected with the dislocation density and with the subgrain size, respectively. A simplified one-parameter treatment is proposed, which gives a precise description of material behaviour far enough from an abrupt perturbation in the loading conditions.