Microstructure, mechanical properties and static recrystallization behavior of the rolled ZK60 magnesium alloy sheets processed by electropulsing treatment

Influences of electropulsing treatment (EPT) on microstructure, mechanical properties and static recrystallization (SRX) behavior of the rolled ZK60 magnesium alloy sheets were investigated. The experimental results indicated that the SRX of the rolled ZK60 alloy sheets processed by EPT was liable to occur compared with that processed by routine heat treatment (RHT). Furthermore, the recrystallization microstructure was refined and the comprehensive mechanical properties were improved tremendously by EPT with a pulse width of 22-25 μs. The grain size was refined from 100 μm to 2 μm, the tensile stress of ZK60 alloy sheets was improved from 210 MPa to 320 MPa and the tensile elongation was increased from 15.7% to 30%. Analyses on measured temperature and theoretical calculation of Fourier heat transfer model were carried out to discuss the effect of Joule heat induced by EPT on recrystallization behavior. Moreover, the SRX mechanism under EPT was studied based on subgrain coalescence theory. EPT accelerated the nucleation of strain-free grains by subgrain coalescence mechanism. An additional energy Ge induced by EPT rather than Joule heat increased the driving force of recrystallization.