New alloys of aluminum piston alloy made by adding more nickel to
their usual composition. Bulk-forming of new alloys at ambient
temperature by conventional methods is not possible. Therefore, the
hot-compression deformation behavior of these alloys has been studied
in this study. Based on the true stress-strain graphs obtained from the
experiments, the constitutive model proposed for these alloys based on
the Johnson-Cook model. Then this model is improved by considering
the coupled effects of the parameters. The accuracy of the proposed
models has been investigated using appropriate statistical analysis,
and as a result, the accuracy of the presented models has been
confirmed. The modified model, compared to original model, in
addition to the higher accuracy, can predict the trend of changes in
flow stress. The study of variations of the model coefficients shows that
with an increasing nickel content in the alloy composition, the strength
and the flow stress of the alloys increased intensely at all temperatures
and strain rates. Also, by increasing the amount of nickel, the effect of
the strain rate on flow stress is reduced