Obtaining of thixotropic structure in AA2024 alloy

In this study, thixotropic microstructure produced in a wrought AA2024alloy for the semi-solid forming was investigated by strain induced meltactivated (SIMA) method. For this purpose, Extruded AA2024 alloy wassubjected to cold deformation at different rates, then heated to a semisolidregion, and cooled in water at room temperature. Microstructureanalysis was achieved by metallographic and quantitative methods.Experimental results showed that spherical shaped thixotropicmicrostructures which required for semi-solid forming can be producedin AA2024 Al alloy by SIMA process. With increasing cold deformationrate, the shape factor increases while the grain size decreases. Withincreasing semi-solid temperature, grain size increased while the shapefactor has not been a significant change. For the production ofthixotropic structure by SIMA process, cold deformation rate wasdetermined to be necessary at least 20%, and there is no need toisothermal holding at semi-solid temperature for thixotropic structuretransformation.