EFFECT OF AGING TREATMENT ON THE MECHANICAL PROPERTIES OF THIXOEXTRUDED 7003 AL WROUGHT ALLOY

摘要

In the present study, the influences of thixoextrusion parameters, such as isothermal holding temperature of billet, initial ram speed and bearing length, on mechanical properties of thixoextruded 7003 Al wrought alloy were investigated. Also, the effect of aging treatment on the mechanical properties of thixoextruded 7003 Al wrought alloy was investigated. The study for thixoextrusion of 7003 Al wrought alloy was carried out with respect to isothermal holding temperature and time during the partial remelting, especially in the low liquid fraction (f_L < 0.3). The liquid fraction and average grain size with respect to isothermal holding time were almost uniform. The maximum extrusion pressure of the thixoextrusion was three times lower than that of the hot extrusion. The tensile and yield strengthes of the thixoextruded bar before T5 aging treatment were lower than those of the hot extruded bar, while the elongation value of the thixoextruded bar was higher than that of the hot extruded bar. However, the tensile and yield strengthes of the thixoextruded bar after aging treatment were similar to hot extruded bar. Therefore, their low tensile and yield strengthes could be improved through appropriate heat treatments.