Effect of Isothermal Forging on the Microstructure and Mechanical Properties of Mg-8Gd-3Y-0.5Zr Alloy

Aiming at the problems of poor plastic forming ability,narrow forging temperature range,and strain rate sensitivity of rare earth magnesium alloys,a study on the microstructure and mechanical properties of Mg-8Gd-3Y-0.5Zr alloy with different isothermal forging processes is carried out.The microstructure and properties of the alloy in the as-cast,isothermal forged,and post-aging states after forging are studied with optical microscope(OM),scanning electron microscope(SEM),and tensile testing.The results show that significant dynamic recrystallization occurs during the isothermal forging process,a fine equiaxed grain structure is formed,and the mechanical properties of the alloy are greatly improved.When the isothermal forging temperature is 460℃ and the strain rate is 0.02 s^(-1),the alloy structure performance is the best,the room temperature tensile yield strength(TYS)is 218 MPa,the ultimate tensile strength(UTS)is 299 MPa,and the fracture elongation(FE)is 19.2%.When the alloy is post-forging artificial aged,theα-Mg matrix is dispersed,the Mg_5(Gd,Y)phase is precipitated,the UTS of the alloy is increased to 392 MPa,and the FE is reduced to 12.0%.