Description
Hot forming of metals is energy- and cost-intensive compared to room temperature forming processes. A promising alternative are electrically assisted forming techniques, where pulsed current is applied during deformation. By exploiting the electroplastic effect, the forming force may be reduced and the elongation can be increased. The electroplastic effect is commonly considered to consist of thermal and athermal components. While the thermal effect (Joule heating) can be beneficial for the forming process, it may be undesirable in some cases. For example, hardening precipitates in age-hardenable aluminum alloys can dissolve or become too coarse. Therefore, it is important to find process conditions that can exploit the electroplastic effect while avoiding excessive heating. However, the mechanisms underlying the athermal electroplastic effect are still not well understood and may differ depending on the material.For studying the effect of electrically assisted forming on the microstructure of 5083, 6082 and 7075 aluminum alloys, we performed tensile tests at various speeds with and without electric current pulses. To separate thermal and athermal effects, temperature was controlled by means of electric current density, pulse duration and intervals, as well as by forced air cooling. Temperature distribution during deformation was recorded using a thermal imaging camera. Additionally, electrically assisted deep-drawing experiments were performed.
To study the microscopic deformation mechanisms underlying the electroplastic effect and separate its thermal and athermal components, we carried out electron backscatter diffraction (EBSD), kernel average misorientation (KAM) and transmission electron microscopy (TEM).
We show that the elongation until fracture can be increased compared to conventional tensile tests. This effect varies considerably depending on electric pulse parameters and aluminum alloy used. The starting point of the pulses is a decisive factor in obtaining a maximum strain increase.
| Period | 23 Jun 2023 |
|---|---|
| Event title | LightMAT: 5th International Conference on Light Materials - Science and Technology |
| Event type | Conference |
| Location | Trondheim, NorwayShow on map |
Research Field
- Advanced Forming Processes and Components