Study on transient rheological behavior of semi-solid A356 alloy applied with step varied shear rate

The influence of step variation of shear rate on transient rheological behavior of semi-solid A356 alloy with different morphologies of primary α-phase was explored through the use of rest time experiment by a self-designed rheometer. The initial shear rate was 367.3 s-1, the variation values of shear rate were 50.2, 83.7, 118.6, 141.8 and 195.3 s-1 respectively. Results indicated that the shear stress changed gradually from the transient peak value to its steady-state value while the shear rate altered from the given value to that of the initial shear rate. Empiric transient rheological equation, τ - τs = τΔp e-kt, which is used to describe the relations of shear stress, shear time, shear rate and morphology of primary α-phase, was obtained by ways of regression analysis.