Effect of preheating temperature on microstructure and properties for AZ31 magnesium alloy cast-rolled sheet in thermo-electropulsing rolling
The"non-thermal effect"is an important mechanism for improving the formability of magnesium alloys in thermo-electropulsing rolling(TER),which is excited by a specific temperature as the energy basis,but the excessively high preheating temperature suppresses the exertion of the"non-thermal effect".Therefore,reasonable selection of preheating temperature becomes the key to magnesium alloy TER.In response to this issue,the influences of warm rolling process(WR)and thermo-electropulsing rolling(TER)at different pre-heating temperatures on the microstructure and mechanical properties of AZ31 magnesium alloy cast-rolled sheet were studied.The results show that the pulse current in TER can accelerate the dynamic recrystallization process and refine the uniform structure.The"non-thermal effect"of the pulse current has a strong correlation with the temperature,which can improve the mechanical properties of the rolled sheet by promoting recrystallization at a lower temperature and accelerate dislocation movement and vacancy diffusion inside the alloy.Within the preheating temperature of 150-300℃,the sample of TER process is superior to the sample of WR process in terms of tensile strength and elongation at the same preheating temperature.At 200℃,the comprehensive mechanical properties of the sheet in TER process are better.Compared with the sheet of WR process at the same preheating temperature,the tensile strength of TER process is increased by about 20.6%and the elongation is increased by about 232.9%.
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