Composition Design And Rolling Process Of Magnesium Alloy Sheets

As an environmental friendly and lightweight structural material,magnesium alloys have been widely concerned in the industry.However,the plasticity of magnesium alloys at room temperature is poor because of the limited slip system,which limits the application of magnesium alloys.In order to expand application areas of magnesium alloys,the plasticity and strength of magnesium alloys are improved by particles strengthening,alloying,hot rolling and heat treatment in this paper.TiB₂ particles are generated in situ by self-propagation high-temperature synthesis,and the AZ80/TiB₂ composites are obtained in the end.The composites are processed by homogenization,hot rolling and annealing.The effects of TiB₂particles on the microstructure and mechanical properties of AZ80 magnesium alloy are studied;Prepare Mg-3Y alloy and investigate the effects of hot rolling temperature,pass reduction and annealing temperature on the plasticity of Mg-3Y sheet.The effects of Sn and Al elements on the mechanical properties of Mg-3Y sheet are studied.The research results are as follows:TiB₂ particles can refine the as-cast microstructure of AZ80 magnesium alloy by heterogeneous nucleation.During the hot rolling process,TiB₂ particles contribute to the start-up of dynamic recrystallization,and it effectively refine recrystallized grains and expand recrystallization area.The characteristics of tri-modal grain size distribution can be observed in the final as-rolled microstructure of AZ80/TiB₂ sheets.TiB₂ particles can weaken the texture intensity of AZ80 sheets,and the polar density decreases from 8.5 to 7.5.With introduction of TiB₂ particles,the tensile strength,yield strength and elongation of as-rolled AZ80 sheets are increased from 282MPa,218MPa,4.1%to 351MPa,253MPa,8.1%,respectively.After annealing at 475℃×15min,the tensile strength,yield strength of the as-rolled Mg-3Y sheet with 70%deformation are decreased from 251MPa,213MPa to 205MPa,125MPa.But the elongation of Mg-3Y sheet is increased significantly from 5.3%to 22.5%.The Erichsen value（IE）of the as-rolled Mg-3Y sheet with 94%deformation is 3.14 after annealing at 475℃×15min.When the content of Sn is 0.3wt.%,the elongation of the as-rolled Mg-3Y-x Sn sheet is increased from 5.3%to 13.8%.When the content of Al is 0.5wt.%,the elongation of the as-rolled Mg-3Y-x Al sheet is increased from 5.3%to 7.9%.