Modification of the Mechanical Anisotropy in Extruded AZ31 Sheets
Due to its low density and good mechanical properties Magnesium holds a high potential for design applications. The investigations discussed herein focus on the use of extruded magnesium sheets as semi-finished products e.g. for subsequent processing by roll forming. Special interest is given by the hcp-structure of magnesium which reduces forming abilities. Extrusion experiments using AZ31 were carried out to investigate the influence of different die geometries (S = sharp-edged and R= radius), billet temperatures (TB= 350°C and 390°C) and extrusion speeds (vext= 2.31 m/min and 9.24 m/min) on mechanical properties, grain structure and texture of said alloy. Two types of sheets with the dimensions of 80 x 1 mm and 80 x 2 mm respectively were produced using the institutes 10 MN extrusion press make SMS MEER. Sheet material with a thickness of 1 mm rolled from cast billets has been used for reference. Microstructural analysis focused on recrystallization behavior and grain size as well as grain distribution within the sheets. Tensile tests in extrusion or rolling direction as well as 45° and 90° to the same showed a strong influence of the specimen orientation on the mechanical properties. Additional Erichsen cupping tests demonstrated the stretch-forming capacity of the different test set-ups.
J.R. Duflou, R. Clarke, M. Merklein, F. Micari, B. Shirvani and K. Kellens
N. Grittner et al., "Modification of the Mechanical Anisotropy in Extruded AZ31 Sheets", Key Engineering Materials, Vol. 473, pp. 490-497, 2011