Inhibition Behavior of Edge Cracking in the AZ31B Magnesium Alloy Cold Rolling Process with Pulsed Electric Current

Abstract

To solve the edge crack problem of AZ31B magnesium alloy cold rolling, a strong pulsed electric current was introduced to the cold rolling process. The influence of intensity, frequency, width of pulsed electric current and other parameters on edge cracking of AZ31B magnesium alloy plate cold rolling was analyzed based on the principle of a single variable. According to the experimental results, the assistance of pulsed electric current cut down edge cracking and the inhibition effect increased obviously with larger current parameters. When the parameters of pulsed electric current reached 4800 A, 500 Hz, 50 μs, zero edge cracking was achieved. Statistics of edge cracks, rolling load change, and microstructure analysis showed that the current thermal effect was not obvious and non-thermal effect played a more important role in the rolling process under pulse electric current. Edge cracks initiate at the shear bands. The addition of pulse current increases the number of shear bands and presents a blanket structure. Therefore, the amount of strain experienced by a single shear band decrease, which has a positive effect on inhibiting the formation of edge cracks. Furthermore, electroplastic rolling refines the grains and weakens the basal plane. As the current parameter increases, the hardness of the magnesium strip decreases and the yield and tensile strengths increase.