Asynchronous Rolling And Electric Pulse Annealing Process Of Mg-13Gd-4Y-2Zn-0.5Zr Rare Earth Magnesium Alloy Experimental Research

The lightweight Mg-Gd-Y-Zn-Zr alloy has excellent corrosion resistance and high temperature resistance,and has broad application prospects in aerospace,automotive,defense and other fields.As-cast rare earth magnesium alloy has poor mechanical properties,so it is usually refined by plastic processing such as rolling and extrusion to improve the mechanical properties of the material.In this paper,Mg-Gd-Y-Zn-Zr alloy was taken as the research object,and single-pass and multi-pass synchronous and asynchronous rolling experiments were carried out to study the effects of different rolling methods and reduction systems on the microstructure and properties of the alloy in order to develop a reasonable rolling process.At the same time,many scholars have found that pulse current can significantly improve the microstructure and properties of magnesium alloy sheets in a short time.At the same time,some scholars have proposed many electric pulse assisted forming processes from the perspective of process.In this paper,the rolled sheet of this material is taken as the research object,and the evolution of microstructure and mechanical properties of the alloy under the action of pulse current is explored.The feasibility and internal mechanism of improving the performance of rolled sheet in a short time by pulse current are revealed.The specific research contents are as follows:Firstly,Mg-13Gd-4Y-2Zn-0.5Zr rare earth magnesium alloy was used as raw material to carry out single-pass synchronous and asynchronous rolling.The annealing scheme of conventional heating furnace after rolling was explored.The microstructure and mechanical properties of the rolled sheet under different annealing schemes were analyzed.The experimental results show that the optimal annealing parameters are 460°C-2h;subsequent single-pass synchronous and asynchronous rolling experiments adopted the optimal annealing scheme.The results show that asynchronous rolling can effectively refine the grain structure and reduce the basal texture strengthSecondly,taking Mg-13Gd-4Y-2Zn-0.5Zr rare earth magnesium alloy sheet as the research object,the multi-pass synchronous and asynchronous rolling experiments were carried out by using the same total reduction rate,rolling temperature and annealing scheme as the rolling experiment in chapter 3.The results show that the grain size of the plate after multi-pass rolling is significantly refined compared with that of the single-pass rolling plate,the volume fraction of the intergranular LPSO phase decreases significantly,the recrystallization volume fraction also increases accordingly,the texture strength is significantly weakened,and the mechanical properties are also significantly improved.However,the yield strength and tensile strength of the plate after multi-pass asynchronous rolling are slightly lower than those of the multi-pass synchronous rolling plate,and the elongation is improved.The comprehensive experimental results show that in order to obtain Mg-13Gd-4Y-2Zn-0.5Zr sheet with better performance,multi-pass rolling process can be used.Finally,in order to explore the feasibility of improving the processing performance of rare earth magnesium alloy rolled sheet by electric pulse treatment instead of conventional annealing treatment,the multi-pass rolled Mg-13Gd-4Y-2Zn-0.5Zr rare earth magnesium alloy in Chapter 4 was taken as the research object,and the electric pulse treatment with the same current density and different time was carried out.The results show that with the increase of pulse current application time,the average grain size decreases first and then increases,the volume fraction of intergranular block LPSO phase decreases gradually,the grain c axis gradually to RD,and the tensile strength,yield strength and elongation increase first and then decrease.The mechanical properties of the sheet are the best when the electric pulse treatment is 10 min.At the same time,the multi-pass asynchronous rolling plate was subjected to electrical pulse treatment for 10 min,and the mechanical properties decreased.Under the combined action of asynchronous rolling shear force and pulse current,the grain c-axis deflected to RD.The experimental results can provide a reference for the electrical pulse treatment process of magnesium alloy after deformation.