Processing of AZ31 magnesium alloy by accumulative roll-bonding at gradient temperature

Meiyan ZHAN 1), Chunming LI 1), Weiwen ZHANG 2) and Datong ZHANG 2) 1) School of Materials Science and Engineering, South China University of Technology, Guangzhou 510640, China 2) National Engineering Research Center of Near-net-shape Forming for Metallic Materials, South China University of Technology, Guangzhou 510640, China

摘 要：In the present investigation a wrought magnesium alloy AZ31 was successfully processed by the accumulative roll-bonding （ARB） at gradient temperature up to six cycles with the lowest temperature of 250 °C. This is performed through different thermomechanical processing routes （different ARB cycles at different temperatures of 350-200 °C）. The microstructures and mechanical properties were investigated. The results indicate that significant grain refinement is observed after the first two cycles at the highest ARB temperature as a result of dynamic recrystallization, which is necessary for the subsequently ARB cycles at relatively lower temperature with the aim to restrict grain growth. No significant finer grain size was observed through the fifth and sixth cycles while the microstructure homogeneity is further improved. The grain structure can be effectively refined at lower ARB processing temperature and higher cycles. The resulting material exhibited high strength and relatively high ductility at ambient temperature when ARB deformed above 250 °C. The mechanical properties of the ARB deformed materials are strongly dependent on several main factors: the amount and the homogeneity of strain achieved, grain size and microstructure homogeneity, textures developed during ARB and interface bonding quality.

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