Study On The Power Spinning Process Of AZ80 Magnesium Alloy

Power spinning is a plastic deformation process to produce high-precision and high-performance rotational components. In this study, the hot power spinning of Mg-8.5%Al-0.5%Zn-0.2%Mn(AZ80) alloy tubes and wheels was conducted innovatively. The effects of solid solution process and processing parameters including spinning temperature, spindle speed, feed ratio and thickness reduction on the microstructures and mechanical properties were investigated. Optical Microscopy(OM) and electron backscatter diffraction(EBSD) techniques were employed to characterize the microstructure evolution of AZ80 alloy during hot power spinning. Tensile test was also carried out at room temperature to analyze the deformation behavior. The results are given as following.The results of tube spinning show that sound AZ80 alloy tubes can be produced by hot flow forming when suitable process parameters are adopted:a temperature range of 350-420℃, a spindle speed range of 200-400 rev/min and a feed ratio range of 0.07-0.15 mm/rev. The maximum thickness reduction by one pass is 45% for AZ80 alloy tube. A more unanimous and raised grain size appeared with deforming temperature from 300 to 420℃. The variation of spindle speed and feed ratio had a slight influence on the microstructure, but an obvious influence on the tensile properties, particularly the elongation. With increasing the thickness reduction, the grain size decreased while the micro-hardness increased significantly. The EBSD results show that the c-axes of most grains are approximately parallel to the radial direction. And likewise, they have a slight deflection towards the axial direction. Furthermore, yield strength(YS) of 181 MPa, ultimate tensile strength(UTS) of 308 MPa and elongation of 9.8% were obtained when the hot flow forming was carried out under a temperature of 420℃, a spindle speed of 400 rev/min, a feed ratio of 0.1mm/rev and a thickness reduction of 45%.The spinning of AZ80 alloy wheels is based on the results of tube spinning and it shows that the results of tube spinning can be applied in wheel spinning successfully. However, the suitable process range of wheel spinning is less than that of tube spinning. A better spinning ability and microstructure can be obtained when the solid solution is 413℃×10h. When the temperature increased, grain size raised and became more unanimous. A larger feed ratio lead to a finer microstructure. Like tube spinning, the grain size decreased while the micro-hardness increased significantly with increasing the thickness reduction. Furthermore, YS of 169 MPa, UTS of 312 MPa and elongation of 14% were obtained when the wheel spinning was carried out under a temperature of 420℃, a feed ratio of 0.1mm/rev and a thickness reduction of 50%. Compared to the as-cast blank, the YS, UTS and elongation increment are 181%,160% and 180%, respectively.