Study On The Rolling Process, Microstructures And Mechanical Properties Of AZ31 And GW123K Alloy Sheets

Light magnesium alloy sheets are widely required in aerospace, automotive, and military industries. Due to their poor plastic deformability at room temperature, magnesium alloy sheets tend to crack during rolling process, resulting in a lower productivity, higher price of magnesium sheets, and greatly restricted the use of magnesium alloys. So in this paper, rolling process, microstructural evolution and mechanical properties of AZ31 and Mg-12Gd-3Y-0.4Zr (GW123K) alloys were investigated, in order to give an example for the coming industrialization of the magnesium alloy sheets in future.The experimental results showed that AZ31 alloy has good millability under the condition of deformation temperature larger than 300℃. The grain size is increased with the rise of rolling temperature,while decreased with the increase of rolling reduction. The rolling reduction hasn’t remarkable effect on mechanical properties of AZ31 Mg alloy sheets. The rolling temperature of 400℃and the reduction in thickness per pass of 30～40% can be applied for small-lot production of magnesium alloy sheets.Electric heated rollers were designed to solve the problem of edge cracking in rolling process. Isothermal rolling were performed on as-cast AZ31 alloy, the results show that heated roller can improve continues millability and the surface quality of the rolled sheets.The rolling experiment of extruded GW123K alloy shows that this alloy has good deformability at 450℃, and the maximum reduction can reached 70% per pass by using heated rollers. As the growth of reduction, the grain size becomes finer, the texture becomes more randomized, and the mechanical property becomes better. Rolled under 450℃with the reduction of 50% per pass can achieved the best properties, the ultimate tensile is 396MPa, yield strength is 323MP, and elongation is 10.4%. Stone-shaped compound and cuboid-shaped compound exist in the rolled alloys as second phases.Participates of GW123K alloy at peak-aged condition isβ’, which acts as the key contributor to the high strength. The highest strength of GW123K at T5 condition shows ultimate tensile strength=486MPa, yield strength=396MPa, corresponding elongation=2.9%.