Researches On Processes Of Differential Speed Rolling And Single Roller Drive Rolling On AZ31 Magnesium Alloy Sheets

The wrought magnesium alloy sheets exhibit great potential for applications due to their excellent mechanical properties. While the well developed basal plane texture during the traditional processes limits the plasticity and the secondary formability. Therefore, improving the mechanical properties and enhancing the formability through weakening the basal plane texture is the key of expanding the applications of magnesium alloy sheets.It mainly investigates the influence of differential speed rolling (DSR) and single roller drive rolling (SRDR) on the microstructures and mechanical properties of AZ31 magnesium alloy sheets. Based on the experiment research and FEM analysis, the relationships between rolling processes and microstructure are discussed, the influence of the basal process parameters on the properties is configured. The main results are drawn as following:(1) The microstructure evolution of the AZ31 Mg alloy sheets prepared by DSR and SRDR processes is investigated. The relationships between process parameters and microstructure, mechanical properties are configured.The research on the roll temperature indicates: when the roll temperature increases form 350℃to 450℃, the number of twin decreases and the grains grow larger. The basal plane texture is weakened. While the sheets are prepared by DSR process, the mechanical properties evolution on rolling direction is: the tensile strength decreases from 275MPa to 250MPa, the elongation increases from 14.5% to 17%. When the sheets are prepared by SRDR process, the evolvement of mechanical properties in rolling direction is: the tensile strength decreases from 325MPa to 285MPa, the elongation increases from 9% to 14%.The research on the reduction per pass of DSR process indicates: when the reduction per pass increases form 5% to 20%, the number of twin increases obviously, the grain size decreases, the basal plane texture is enhanced. The tensile strength in rolling direction increases from 250MPa to 300MPa, the elongation decreases from 18% to 15%. The grain orientation is influenced by roll path. In B and C paths, the deformation is more symmetrical and the grain size is smaller. In A and D paths, the basal plane texture is weaker. Compared with of SRDR process, DSR process can weak the basal plane texture more efficiently. (2) The room temperature drawabilities of AZ31 Mg alloy sheets produced by DSR and SRDR processes are investigated.When the roll temperature is 450℃, the reduction per pass is 10%, the roll speed ratio is 1.1, the Erichsen value of the sheets prepared by DSR is 5.84mm after anneal treatment at 300℃for 60min. After a same anneal treatment, the n value of the sheets prepared by the SRDR is above 0.294, and the Erichsen value is up to 3.82mm.