Characterization of Al 7075 alloys after cold working and heating in the semi-solid temperature range

The effects of cold working and heating conditions on the microstructures of 7075 aluminum alloys were investigated in the SIMA process. Swaging was conducted to control the recrystallization structures in the mushy zone. Different levels of cold working, holding temperatures and holding times were used in this investigation. It was found that at least 50% cold working was necessary in order to obtain a uniform and fine microstructures during semi-solid heating. The holding time should be between 2 and 3 min in order to prevent grain growth. The optimum heat treatment conditions for the thixoforged 7075 parts were investigated. The mechanical properties of thixoforged 7075 aluminum alloys were compared with those of conventionally hot forged alloys.