Flow Stress and Hot Deformation Activation Energy of 6082 Aluminium Alloy Influenced by Initial Structural State

Abstract

Stress-strain curves of the EN AW 6082 aluminium alloy with 1.2 Si-0.51 Mg-0.75 Mn (wt.%) were determined by the uniaxial compression tests at temperatures of 450–550 °C with a strain rate of 0.5–10 s−1. The initial structure state corresponded to three processing types: as-cast structure non-homogenized or homogenized at 500 °C, and the structure after homogenization and hot extrusion. Significantly higher flow stress appeared as a result of low temperature forming of the non-homogenized material. Hot deformation activation energy Q-values varied between 99 and 122 kJ·mol−1 for both homogenized materials and from 200 to 216 kJ·mol−1 for the as-cast state, while the Q-values calculated from the measured steady-state stress were always higher than those calculated from the peak stress values. For the extruded state of the 6082 alloy, the physically-based model was developed to reliably predict the flow stress influenced by dynamic softening, temperature, strain rate, and true strain up to 0.6.

Correlation among the Power Dissipation Efficiency, Flow Stress Course, and Activation Energy Evolution in Cr-Mo Low-Alloyed Steel

“…The creation of the AE maps requires the calculation of activation energy values under all thermomechanical conditions. In most cases, however, the activation energy is considered to be a material constant (so-called apparent activation energy) or, at most, strain dependent [21,26,[51][52][53][54]. In order to deal with the activation energy as a strain, strain rate, and temperature dependent parameter, the method utilized, e.g., in [55,56] has been employed.…”

Forming and Heat Treatment of Modern Metallic Materials

“…The division and classification of contributions is made on the basis of the main problems published in the text. The first can be characterized as materials for forming and their study, together with hot forming, where the papers are presented [1][2][3][4]. The second group consists of contributions devoted to shaping and unconventional shaping [5][6][7].…”

“…In the presented work [1], based on a dynamic material model, processing maps of low-alloy steel 10CrMo9-10 were compiled, using two sets of flow curve data. For the extruded state of the 6082 alloy, the physically based model was developed to reliably predict the flow stress influenced by dynamic softening, temperature, strain rate, and true strain up to 0.6 [2]. The relationship between microstructure parameters and mechanical properties was studied by authors [3].…”

“…The determination of the stress-deformation curves of aluminum alloy EN AW 6082 with 1.2 Si-0.51 Mg-0.75 Mn (wt.%) by uniaxial compression tests at temperatures of 450-550 • C with a deformation rate of 0.5-10 s −1 was described by Schindler et al [2]. The initial state of the structure corresponded to three types of processing: the cast structure either not homogenized or homogenized at 500 • C, and the structure after homogenization and hot extrusion.…”

Hot Deformation Behaviour of Mn–Cr–Mo Low-Alloy Steel in Various Phase Regions

“…The Q value is ideally the material constant depending only on the chemical composition and microstructure of the particular material. For simplification, it is possible to omit the experimentally verified fact that the Q value also depends on the amount of strain [8][9][10][11][12][13][14] or even on the combination of the strain rate and temperature (see, e.g., the apparent activation energy map for Ni-containing Fe-Mn-Al-C lightweight duplex steel in [15]).…”