The hot deformation processes taking place in commercial purity aluminium with 0.22% Fe and 0.14% Si content are investigated by tensile test, impression creep, and direct extrusion experiments. The stress‐srain rate relationship obtained at different temperatures can be described by a power function. In the low and medium stress regions corresponding to strain rates between 10−6 and 10° s−1 and to temperatures higher than 300 to 350 °C the deformation process can be characterized with a constant activation energy of about 200 kJ/mol and with a stress exponent of about n = 7 independently of the mode of deformation. These relatively high values may be connected with the large number of intermetallic particles inherited from the cast state. At higher stresses attained by lowering the temperature below 350 °C the stress exponent is increased up to n = 12 to 13, and the activation energy is decreased to that of grain boundary diffusion. The latter process is also found to be similar in the case of creep and hot extrusion processes.
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics