Semi-solid 2024 aluminum alloy billet was prepared by recrystallization and partial remelting technology.Microstructure evolution was observed at different remelting temperature and holding time

and effects of processing parameters on grain size and spheroidization rate were analyzed.Based on thixo-forming casting

the difference of mechanical properties was described at varied position on the samples with different billet height.The results show that microstructure of the billet gradually undergoes the disappearance of extruded fibrous tissue

the generation ofα-Al recrystallized grains and the spheroidization and growth ofα-Al grains with increasing in holding time

and the process is accelerated with the remelting temperature increase.The size and spheroidization rate of the semi-solid grains are increased with the increase of remelting temperature and holding time.The average grain size with approximately 75μm and spheroidized rate of 0.74 can be obtained at 613

6

21℃for 20

3

0min

and the tensile strength of the thixoforming parts can be reached up to 383 MPa.The tensile strength exbibits greatly different at different position due to the parts shape and forming characteristics.