THE EFFECT OF REHEATING TEMPERATURE ON THE PRODUCTION OF THIXOTROPIC STRUCTURE WITH SIMA PROCESS IN AA2024 ALLOY

In this study, the production of required thixotropic microstructure for the semi-solid forming in a wrought aluminium alloy aa2024 was investigated by strain induced melt activated (sima) method. for this purpose, aa2024 alloy as extruded state were subjected to cold deformation at %20 rate, and then reheated to different semi-solid temperatures which corresponded to 30%, 40% and 50% liquid ratios, and cooled in water held at room temperature. microstructure analysis was achieved by metallographic and quantitative methods. experimental results showed that, globular shaped thixotropic microstructures which required for semi-solid forming can be produced in aa2024 al alloy by sima process. with increasing semi-solid temperature, the grain size increases while the shape factor was not change significantly. for the production of thixotropic structure by sima process, there is no need to isothermal holding at semi-solid temperature for thixotropic structure transformation.