Effect of reduction rate distribution of two cold rolling on microstructure and mechanical properties of LZ91 Mg-Li alloy
Xu Chenyang;You Dongyang;Shi Yansong;Zhang Yule;Wang Yanjiao;Sun Yuanpei;School of Mechanical Electronic and Information Engineering,China University of Mining and Technology;
By using metallographic microscope, scanning electron microscope, universal testing machine and other equipment, LZ91 magnesium-lithium alloy sheet is taken as the research object. The sheet with accumulative deformation rate of 30%, 40% and 50% is heat treated at 250 ℃ for 1.5 h, and then cold-rolled twice to make the total deformation rate reach 80%. The results show that the total reduction rate is constant, and the microstructure and mechanical properties of LZ91 magnesium-lithium alloy sheet are greatly influenced by the reduction rate distribution of two cold rolling. After secondary cold rolling, the orientation of two-phase structure appears to a certain extent. Among the microstructures with 40% primary cumulative reduction and 40% secondary cumulative reduction, the spheroidized alpha-phase becomes a fine "flat spherical" structure around the beta-phase grains, with the largest number of fine grains compared with 30%+50% and 50%+30%. At the same time, there is second-phase strengthening to optimize the mechanical properties. The maximum tensile strength is about 290 MPa, and the elongation is 30%.