Dependence of Microstructure, Texture and Tensile Properties on Working Conditions in Indirect-Extruded Mg-6Sn Alloys

Dependence of microstructure, texture and tensile properties on working conditions (ram speed and initial billet temperature) in indirect extruded Mg-6wt%Sn alloys were investigated by optical microscope (OM), scanning electronic microscope (SEM), X-ray diffraction (XRD) and a standard universal testing machine. Results show that the grain size, the recrystallization fraction and the dynamic precipitate fraction of the alloys are greatly affected by the working conditions. Their texture intensities weaken as the ram speed and the initial billet temperature increase. Tested in the different working conditions, the ultimate tensile strengths of the Mg-6Sn alloys extruded at high working temperature (controlled by initial billet temperature and ram speed) are remarkably better than those at the medium and low temperatures. The tensile properties of the alloys extruded at the high working temperature are similar to those of a commercial AZ31 alloy extruded at the low temperature, showing the possibility of the development of high speed extruded Mg alloys based on Mg-6Sn alloy.