Grain size and texture changes of magnesium alloy AZ31 during multi-directional forging
(1. School of Materials Science and Engineering, Central South University, Changsha 410083, China;2. Key Laboratory of Nonferrous Metal Materials Science and Engineering, Ministry of Education,Central South University, Changsha 410083, China;3. Department of Mechanical Engineering and Intelligent Systems, UEC Tokyo, Tokyo 182-8585, Japan)
Abstract: Grain size and texture changes of magnesium alloy AZ31 were studied in multidirectional forging(MDF) under decreasing temperature conditions. MDF was carried out up to large cumulative strains of 4.8 with changing the loading direction during decrease in temperature from pass to pass. MDF can accelerate the uniform development of fine-grained structures and increase the plastic workability at low temperatures. As a result, the MDFed alloy shows excellent higher strength as well as moderate ductility at room temperature even at the grain size below 1μm. Superplastic flow takes place at 423 K and depends on the anisotropy of MDFed samples. The mechanisms of strain-induced fine-grained structure development and of the plastic deformation were discussed in detail.
Key words: magnesium alloy; severe plastic deformation; multidirectional forging; texture; continuous dynamic recrystallization