Semi-solid billet prepared by the direct semi-solid isothermal treatment of cold-rolled ZL104 aluminum alloy

The direct semi-solid isothermal treatment (DSSIT) process is proposed to process the cold-rolled ZL104 aluminum alloy to manufacture the semi-solid billet. The influence of two process parameters (i.e. maintained temperature and duration time) on the microstructure and hardness of the semi-solid billet (ZL104 aluminum alloy) were experimentally examined. Results revealed that the average size of grains enlarged and the shape factor was improved with an elevation in the maintained temperature. The shape factor increased with the increase in the duration time while the average grain size enlarged when the duration time was prolonged from 5 to 20 min at 570 °C. The hardness of the studied aluminum alloy decreased due to the increase in the average size of grains with raising of either the maintained temperature or the duration time. The optimal maintained temperature was obtained as 570 °C while the duration time was found as 5 min for preparing the semi-solid ZL104 aluminum alloy. Under the optimal process parameters, the average size of the grain, the shape factor, and the hardness were obtained as 35.88 µm, 0.81 and 55.24 MPa, respectively. The coarsening rate constant in the Lifshitz-Slyozov-Wagner relationship at 570 °C was found at 1357.2 μm3/s.