| In the age of limited fossil energy resources, the demand for lightweightconstruction materials is growing in order to reduce energy consumption and tolower the environmental impact. In this regard, magnesium and its alloys haveattracted a lot of attention in recent research. Magnesium is abundant andpossessed positive technological properties such as a low density and high specificstrength together with a good recyclability.In this paper, the effect of electropulsing treatment (EPT) on themicrostructure evolution and the mechanical properties was studied. EPT withdifferent parameters was analyzed by using OM. SEM,EBSD etc. The thermaland athermal effect of EPT is researched and the mechanism of therecrystallization under EPT was also revealed.The results indicate that EPT accelerates tremendously the recrystallizationof deformed AZ31magnesium alloy and the microstructure of this alloy is refined.After EPT with a pluse-width of20μs, a current density of3.508×109A/m2, aduty ratio of0.002and a processing time of5min, recrystallization occurred inthe AZ31alloy at low temperature below359K. The average grain size of AZ31alloy is refined from72μm to2μm, the tensile strength is295MPa, and the elongation is20%.Current research also has shown that EPT with high current density and lowduty ratio can refine the deformed AZ31magnesium alloy significantly. The EPThas two principal effects on the samples, the Joule heat and the athermal effect.Based on the experimental data and the theory analysis, we think that the athermaleffect plays an essential role in the recrystallization of the deformed alloys underEPT and accelerates the nucleation rate of recrystallization during EPT.Furthermore, subsequent growth of the recrystallization grains is more dependenton the Joule heat than the athermal effect. As a result, in order to achieve refinedrecrystallization grains, the athermal effect should be strengthened while thethermal effect should be weakened during EPT. |
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