The effect of pulsed electric current on the structural and mechanical behavior of 6016 aluminium alloy in different states of hardening

Abstract

This study presents the effect of high current pulses on the structural and mechanical behavior of the 6016 aluminium alloy in three different states of hardening: naturally aged, super saturated, and annealed. The 6016 aluminium alloy was used for the first time in terms of electrically-assisted forming. The influence of the application of different current parameters on the material behavior was conducted. The study of electrically-assisted tensile tests showed that the application of current pulses results in a distinct response of the material, depending on the hardening state. Although in a hardened state, the mechanical properties and plasticity are deteriorated, in the solution treated state, they are improved. For the changes of the material properties is responsible the interaction of the flowing current with the precipitates and the aging process. The new parameters were proposed to describe the distinctions in the material properties between the different states of hardening of the aluminium alloy during the electrically-assisted tension. The material examination was conducted using light and scanning electron microscopy, using also electron backscattered diffraction methods. The application of, for example, the grain orientation spread parameter demonstrated the presence of recrystallized grains, in electrically-assisted specimens.

A Pulsed Current Application to the Deformation Processing of Materials

“…Thus, paper [ 54 ] shows the possibility of additional structure refinement due to the particle formation. Work [ 42 ] describes the structural changes in 6016 aluminum alloy in various initial states (quenched, annealed, and naturally aged) during tension with and without current. The authors noted brittle intergranular fracture in all states; however, they observed some differences in fracture for specimens under tension with and without current ( Figure 12 ).…”

“…However, some researchers note a decrease in plasticity under the action of current, but these effects are found in alloys disposed to aging [ 42 ]. The microhardness ( Figure 13 a) of naturally aged 6016 aluminum alloy was reduced by a combination of rolling and current.…”

“…The parameter d in Figure 13 is the distance from the edge of the fracture along the rolling direction after a tensile test. However, in the case of the state after quenching from 525 °C in the water, the applied current led to an intensification of the aging process without reducing its plasticity at the selected current regimes, as well as to an increase in strength and microhardness ( Figure 13 b) [ 42 ]. However, strength and ductility decreased for the alloy after natural aging, as shown in this study.…”

“… The SEM images of fracture surface under the tension of 6016 aluminum-based alloy without current ( a , c ) and with current ( b , d ) in the state after natural aging ( a , b ) and quenching ( c , d ) [ 42 ]. …”

“… Microhardness of 6016 aluminum alloy after deformation with and without current: ( a ) natural aging; ( b ) quenching (525 °C/water) [ 42 ]. …”